U.S. patent application number 17/404066 was filed with the patent office on 2021-12-02 for automated treatment in particle therapy.
The applicant listed for this patent is Mevion Medical Systems, Inc.. Invention is credited to James Cooley, Mark R. Jones, Stanley J. Rosenthal, Gerrit Townsend Zwart.
Application Number | 20210370096 17/404066 |
Document ID | / |
Family ID | 1000005782736 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210370096 |
Kind Code |
A1 |
Zwart; Gerrit Townsend ; et
al. |
December 2, 2021 |
AUTOMATED TREATMENT IN PARTICLE THERAPY
Abstract
An example particle therapy system includes a particle beam
output device to direct output of a particle beam; a treatment
couch to support a patient containing an irradiation target, with
the treatment couch being configured for movement; a movable device
on which the particle beam output device is mounted for movement
relative to the treatment couch; and a control system to provide
automated control of at least one of the movable device or the
treatment couch to position at least one of the particle beam or
the irradiation target for treatment of the irradiation target with
the particle beam and, following the treatment of the irradiation
target with the particle beam, to provide automated control of at
least one of the movable device or the treatment couch to
reposition at least one of the particle beam or the irradiation
target for additional treatment of the irradiation target with the
particle beam.
Inventors: |
Zwart; Gerrit Townsend;
(Durham, NH) ; Jones; Mark R.; (Reading, MA)
; Cooley; James; (Andover, MA) ; Rosenthal;
Stanley J.; (Wayland, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mevion Medical Systems, Inc. |
Littleton |
MA |
US |
|
|
Family ID: |
1000005782736 |
Appl. No.: |
17/404066 |
Filed: |
August 17, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15441170 |
Feb 23, 2017 |
11103730 |
|
|
17404066 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 2005/1095 20130101;
A61N 5/1049 20130101; A61N 2005/1087 20130101; A61N 5/1081
20130101; A61N 5/1065 20130101; A61N 5/1043 20130101; A61N 5/107
20130101; A61N 5/1067 20130101; A61N 5/1045 20130101; A61N 5/1069
20130101 |
International
Class: |
A61N 5/10 20060101
A61N005/10 |
Claims
1. A particle therapy system comprising: a particle beam output
device to direct output of a particle beam; a treatment couch to
support a patient containing an irradiation target, the treatment
couch being configured for movement; a movable device on which the
particle beam output device is mounted for movement relative to the
treatment couch; and a control system to provide automated control
of at least one of the movable device or the treatment couch to
position at least one of the particle beam or the irradiation
target for treatment of the irradiation target with the particle
beam and, following the treatment of the irradiation target with
the particle beam, to provide automated control of at least one of
the movable device or the treatment couch to reposition at least
one of the particle beam or the irradiation target for additional
treatment of the irradiation target with the particle beam.
2. The particle therapy system of claim 1, further comprising: a
scanning system comprising components to move the particle beam
relative to the irradiation target; wherein the control system is
configured to provide automated control of one or more of the
components to position the particle beam for the treatment of the
irradiation target with the particle beam and, following the
treatment of the irradiation target with the particle beam, to
provide automated control of one or more of the components to
reposition the particle beam for the additional treatment of the
irradiation target with the particle beam.
3. The particle therapy system of claim 2, wherein the one or more
components comprise one or more scanning magnets.
4. The particle therapy system of claim 2, wherein the one or more
components comprise an energy degrader, the energy degrader
comprising one or more structures that are movable into, and out
of, a path of the particle beam.
5. The particle therapy system of claim 1, wherein the control
system is configured to provide the automated control of at least
one of the movable device or the treatment couch to treat a first
part of the irradiation target using a first beam field of the
particle beam and, following treatment of the first part of the
irradiation target with the particle beam, to provide the automated
control of at least one of the movable device or the treatment
couch to reposition at least one of the particle beam or the
irradiation target to treat a second part of the target using a
second beam field of the particle beam.
6. The particle therapy system of claim 5, wherein the particle
beam output device comprises a particle accelerator; wherein at an
area between the first beam field and the second beam field, the
particle beam for the first beam field and the particle beam for
the second beam field overlap at least partly; and wherein the
control system is configured to provide automated control of the
particle accelerator to control intensities of the particle beam
for the first beam field and the particle beam for the second beam
field so that cumulative intensities at points of overlap between
the particle beam for the first beam field and the particle beam
for the second beam field reach a target beam intensity.
7. The particle therapy system of claim 5, wherein the particle
beam output device comprises a particle accelerator; wherein at an
area between the first beam field and the second beam field, the
particle beam for the first beam field and the particle beam for
the second beam field overlap at least partly; and wherein the
control system is configured to provide automated control of the
particle accelerator to control intensities of the particle beam
for the first beam field and the particle beam for the second beam
field so that cumulative intensities at points of overlap between
the particle beam for the first beam field and the particle beam
for the second beam field do not deviate from a target beam
intensity by more than a defined amount.
8. The particle therapy system of claim 1, wherein the control
system is configured to control the treatment couch to implement
translational motion.
9. The particle therapy system of claim 1, wherein the control
system is configured to control the treatment couch to implement
rotational motion.
10. The particle therapy system of claim 1, further comprising: an
imaging system to capture images of the irradiation target during
treatment; wherein the control system is configured to control the
imaging system to capture one or more first images of the patient
after positioning the at least one of the particle beam or the
irradiation target for the treatment and before the treatment of
the irradiation target with the particle beam, and the control
system is configured to control the imaging system to capture one
or more second images of the patient after repositioning the at
least one of the particle beam or the irradiation target for the
additional treatment and before the additional treatment.
11. The particle therapy system of claim 10, wherein the control
system is configured to use the first image to identify a first
location of the irradiation target in a treatment space of the
particle therapy system, and the control system is configured to
use the second image to identify a second location of the
irradiation target in the treatment space.
12. The particle therapy system of claim 1, wherein the control
system is configured to receive a treatment plan from a treatment
planning system, and to interpret the treatment plan to implement
the control of at least one of the movable device or the treatment
couch, the treatment plan containing information identifying
positions of at least one of the movable device or the treatment
couch during treatment.
13. The particle therapy system of claim 1, wherein the control
system is configured to provide automated control of at least one
of the movable device or the treatment couch independent of an
isocenter defined in the particle therapy system.
14. The particle therapy system of claim 1, wherein automated
control of at least one of the movable device or the treatment
couch is implemented absent human intervention.
15. The particle therapy system of claim 1, wherein the particle
beam output device comprises a particle accelerator; wherein the
control system is configured to provide automated control of an
operation of the particle accelerator to position at least one of
the particle beam or the irradiation target for treatment of the
irradiation target with the particle beam and, following the
treatment of the irradiation target with the particle beam, to
provide automated control of the operation of the particle
accelerator to reposition at least one of the particle beam or the
irradiation target for the additional treatment of the irradiation
target with the particle beam.
16. The particle therapy system of claim 1, wherein the particle
beam output device comprises a synchrocyclotron having a
superconducting electromagnetic structure.
17. The particle therapy system of claim 1, wherein the particle
beam output device comprises a variable-energy synchrocyclotron
having a superconducting electromagnetic structure.
18. The particle therapy system of claim 1, wherein the particle
beam output device comprises a beam spreader.
19. The particle therapy system of claim 18, wherein the beam
spreader comprises one or more scanning magnets or one or more
scattering foils.
20. The particle therapy system of claim 1, further comprising: a
configurable collimator between the particle beam output device and
the patient, the configurable collimator comprising leaves that are
controllable to define an edge to block a first part of the
particle beam from reaching the patient while collimating a second
part of the particle beam that passes to the patient, the
configurable collimator being controllable to trim an area as small
as a single spot size of the particle beam.
21. The particle therapy system of claim 1, wherein the control
system is configured to provide automated control over movement of
the particle beam output device to implement translational movement
of the particle beam output device from a first location to a
second location to position the particle beam for treatment of the
irradiation target with the particle beam and, following the
treatment of the irradiation target with the particle beam, to
provide automated control over further movement of the particle
beam output device to implement translational movement of the
particle beam output device from the second location to a third
location to reposition the particle beam for treatment of the
irradiation target with the particle beam.
22. The particle therapy system of claim 1, wherein the control
system is configured to provide automated control over movement of
the particle beam output device to pivot the particle beam output
device from a first orientation to a second orientation to position
the particle beam for treatment of the irradiation target with the
particle beam and, following the treatment of the irradiation
target with the particle beam, to provide automated control over
further movement of the particle beam output device to pivot the
particle beam output device from the second orientation to a third
orientation to reposition the particle beam for treatment of the
irradiation target with the particle beam.
23. The particle therapy system of claim 1, further comprising: a
scanning system comprising components to move the particle beam
relative to the irradiation target, at least some of the components
being mounted for movement towards, and away from, the irradiation
target; wherein the control system is configured to provide
automated control of the at least some of the components to
position the particle beam for the treatment of the irradiation
target with the particle beam and, following the treatment of the
irradiation target with the particle beam, to provide automated
control of the at least some of the components to reposition the
particle beam for the additional treatment of the irradiation
target with the particle beam.
24. The particle therapy system of claim 23, further comprising: a
carriage on which the at least some of the components are mounted,
the carriage being mounted to at least one track to enable movement
along a path of the particle beam.
25. The particle therapy system of claim 24, wherein the carriage
is controllable to move along the at least one track to control a
size of a spot produced by the particle beam.
26. The particle therapy system of claim 24, wherein the carriage
is controllable to move along the at least one track in
coordination with movement of at least one of the movable device or
the treatment couch.
27. The particle therapy system of claim 1, wherein the movable
device comprises a rotatable gantry.
28. The particle therapy system of claim 1, wherein the movable
device comprises one or more robotic arms.
29. The particle therapy system of claim 1, further comprising: a
scanning system comprising components to move the particle beam
relative to the irradiation target, the scanning components being
mounted on a carriage that is movable along a beamline of the
particle beam; wherein the control system is configured to provide
automated control of the carriage to position the particle beam for
the treatment of the irradiation target with the particle beam and,
following the treatment of the irradiation target with the particle
beam, to provide automated control of the carriage to reposition
the particle beam for the additional treatment of the irradiation
target with the particle beam.
30. A method comprising: supporting a patient containing an
irradiation target on a treatment couch, the treatment couch being
configured for movement; mounting a particle beam output device on
a movable device for movement relative to the treatment couch, the
particle beam output device for directing output of a particle beam
to treat the irradiation target; and providing automated control of
at least one of the movable device or the treatment couch to
position at least one of the particle beam or the irradiation
target for treatment of the irradiation target with the particle
beam and, following treatment of the irradiation target with the
particle beam, providing automated control at least one of the
movable device or the treatment couch to reposition at least one of
the particle beam or the irradiation target for additional
treatment of the irradiation target with the particle beam.
31. The method of claim 1, wherein the particle beam is a proton
beam.
32. A particle therapy system comprising: a treatment couch to
support a patient containing an irradiation target, the treatment
couch being configured for movement; a particle beam output device
to direct output of a particle beam, the particle beam output
device being arranged for movement relative to the treatment couch;
and a control system to control positioning of the particle beam
output device and the treatment couch using degrees of freedom that
exceed isocentric rotation of the particle beam output device and
the treatment couch.
33. The particle therapy system of claim 32, wherein the particle
beam output device comprises scanning components to scan the
particle beam relative to the irradiation target, the scanning
components comprising one or more scanning magnets; and wherein the
control system is configured to control a position of the particle
beam by controlling operation of one or more of the scanning
components
34. The particle therapy system of claim 32, wherein the control
system is configured to control positioning of the particle beam
output device and the treatment couch absent user intervention.
35. The particle therapy system of claim 32, wherein the control
system is configured to control positioning of the particle beam
output device and the treatment couch automatically for multiple
beam fields.
36. The particle therapy system of claim 32, wherein the particle
beam output device is controllable to move linearly between a first
position and a second position.
37. The particle therapy system of claim 32, wherein the particle
beam output device is controllable to pivot relative to the
treatment couch.
38. The particle therapy system of claim 32, wherein the particle
beam output device is controllable to rotate relative to the
treatment couch.
39. The particle therapy system of claim 32, wherein the particle
beam output device comprises a particle accelerator.
40. The particle therapy system of claim 32, wherein the particle
beam output device is configured to produce a beam field of 30 cm
by 30 cm or less.
41. A particle therapy system comprising: a treatment couch to
support a patient containing an irradiation target, the treatment
couch being configured for movement; an apparatus to direct output
of a particle beam; a movable device on which the apparatus is
mounted to move the apparatus relative to the treatment couch, the
apparatus being mounted relative to the treatment couch to produce
a beam field of 30 cm by 30 cm or less; and a control system to
provide automated positioning of at least one of the apparatus or
the treatment couch for treatment of a first part of the
irradiation target with the particle beam and, following the
treatment of the first part of the irradiation target with the
particle beam, to provide automated repositioning at least one of
the apparatus or the treatment couch for treatment of a second part
of the irradiation target with the particle beam.
42. The particle therapy system of claim 41, wherein at least one
of the automated positioning or the automated repositioning
includes translational movement.
43. The particle therapy system of claim 41, wherein the apparatus
comprises a beam spreader to deliver the particle beam via a
transmission channel.
44. The particle therapy system of claim 41, wherein the apparatus
comprises a particle accelerator configured to generate the
particle beam.
45. The particle therapy system of claim 41, wherein the apparatus
is mounted to produce a beam field of 20 cm by 20 cm or less.
46. The particle therapy system of claim 41, wherein the apparatus
comprises a synchrocyclotron having a weight that is within a range
of 5 tons to 30 tons and that occupies a volume of less than 4.5
cubic meters.
47. The particle therapy system of claim 41, further comprising: a
collision avoidance system to detect positions of one or more
components of the particle therapy system and to provide
information about positions to the control system; wherein the
control system is configured to control operation of the one or
more components based on the information.
48. The particle therapy system of claim 41, wherein the control
system is configured to provide automated control of the particle
beam to control intensities of the particle beam so that cumulative
intensities at points of overlap between a particle beam for a
first beam field and a particle beam for a second beam field remain
within a range of a target beam intensity.
Description
TECHNICAL FIELD
[0001] This disclosure relates generally to a particle therapy
system that implements automated treatment.
BACKGROUND
[0002] Traditionally, particle therapy has been delivered
isocentrically, where the approximate center of an irradiation
target in a patient is positioned at a unique location, known as
the isocenter, in a treatment space. A radiation source is arranged
so that a central axis of the radiation source points to the
isocenter. The radiation source is rotated around the isocenter,
and the patient is also rotated around this same isocenter. By
positioning the radiation source and the patient in this manner,
the target may be irradiated from a number of projections, which
correspond to different beam fields. As a result, a radiation dose
to the target may be increased, while radiation to surrounding
normal tissue may be reduced.
[0003] A dosimetrist working with a treatment planning system (TPS)
may choose the projections. The TPS uses information about the
patient's anatomy, the radiation source, and other available
information to determine the planned dose for each chosen
projection. The number of projections has typically been chosen so
that the quality of the therapy is enhanced, without unduly
burdening the radiation delivery process. Traditionally, treatment
is administered for each projection by verifying the positioning of
the patient and/or the radiation emitter prior to the first
application of radiation. A radiation therapist enters the
treatment room before the first projection and between each
successive projection to reposition the patient and/or a radiation
emitter as specified by the treatment plan.
[0004] This required manual intervention by a radiation therapist
makes it difficult, and time-consuming, to implement a large number
of projections. Also, the quality of the treatment can be affected
in areas where projections may overlap.
SUMMARY
[0005] An example particle therapy system comprises a particle beam
output device to direct output of a particle beam; a treatment
couch to support a patient containing an irradiation target, with
the treatment couch being configured for movement; a movable device
on which the particle beam output device is mounted for movement
relative to the treatment couch; and a control system to provide
automated control of at least one of the movable device or the
treatment couch to position at least one of the particle beam or
the irradiation target for treatment of the irradiation target with
the particle beam and, following the treatment of the irradiation
target with the particle beam, to provide automated control of at
least one of the movable device or the treatment couch to
reposition at least one of the particle beam or the irradiation
target for additional treatment of the irradiation target with the
particle beam. The example particle therapy system may include one
or more of the following features, either alone or in
combination.
[0006] The example particle therapy system may include a scanning
system comprising components to move the particle beam relative to
the irradiation target. The control system may be configured to
provide automated control of one or more of the components to
position the particle beam for the treatment of the irradiation
target with the particle beam and, following the treatment of the
irradiation target with the particle beam, to provide automated
control of one or more of the components to reposition the particle
beam for the additional treatment of the irradiation target with
the particle beam. The one or more components may comprise one or
more scanning magnets. The one or more components may comprise an
energy degrader, with the energy degrader comprising one or more
structures that are movable into, and out of, a path of the
particle beam.
[0007] The control system may be configured to provide the
automated control of at least one of the movable device or the
treatment couch to treat a first part of the irradiation target
using a first beam field of the particle beam and, following
treatment of the first part of the irradiation target with the
particle beam, to provide the automated control of at least one of
the movable device or the treatment couch to reposition at least
one of the particle beam or the irradiation target to treat a
second part of the target using a second beam field of the particle
beam.
[0008] The particle beam output device may comprise a particle
accelerator. At an area between the first beam field and the second
beam field, the particle beam for the first beam field and the
particle beam for the second beam field may overlap at least
partly. The control system may be configured to provide automated
control of the particle accelerator to control intensities of the
particle beam for the first beam field and the particle beam for
the second beam field so that cumulative intensities at points of
overlap between the particle beam for the first beam field and the
particle beam for the second beam field reach a target beam
intensity.
[0009] The particle beam output device may comprise a particle
accelerator. At an area between the first beam field and the second
beam field, the particle beam for the first beam field and the
particle beam for the second beam field may overlap at least
partly. The control system may be configured to provide automated
control of the particle accelerator to control intensities of the
particle beam for the first beam field and the particle beam for
the second beam field so that cumulative intensities at points of
overlap between the particle beam for the first beam field and the
particle beam for the second beam field do not deviate from a
target beam intensity by more than a defined amount.
[0010] The control system may be configured to control the
treatment couch to implement translational motion. The control
system may be configured to control the treatment couch to
implement rotational motion.
[0011] The example particle therapy system may comprise an imaging
system to capture images of the irradiation target during
treatment. The control system may be configured to control the
imaging system to capture one or more first images of the patient
after positioning the at least one of the particle beam or the
irradiation target for the treatment and before the treatment of
the irradiation target with the particle beam, and the control
system may be configured to control the imaging system to capture
one or more second images of the patient after repositioning the at
least one of the particle beam or the irradiation target for the
additional treatment and before the additional treatment. The
control system may be configured to use the first image to identify
a first location of the irradiation target in a treatment space of
the particle therapy system (e.g., in a proton center), and the
control system may be configured to use the second image to
identify a second location of the irradiation target in the
treatment space.
[0012] The control system may be configured to receive a treatment
plan from a treatment planning system, and to interpret the
treatment plan to implement the control of at least one of the
movable device or the treatment couch. The treatment plan may
contain information identifying positions of at least one of the
movable device or the treatment couch during treatment.
[0013] The control system may be configured to provide automated
control of at least one of the movable device or the treatment
couch independent of an isocenter defined in the particle therapy
system. Automated control of at least one of the movable device or
the treatment couch may be implemented absent human
intervention.
[0014] The particle beam output device may comprise a particle
accelerator. The control system may be configured to provide
automated control of an operation of the particle accelerator to
position at least one of the particle beam or the irradiation
target for treatment of the irradiation target with the particle
beam and, following the treatment of the irradiation target with
the particle beam, to provide automated control of the operation of
the particle accelerator to reposition at least one of the particle
beam or the irradiation target for the additional treatment of the
irradiation target with the particle beam.
[0015] The particle beam output device may comprise a
synchrocyclotron having a superconducting electromagnetic
structure. The particle beam output device may comprise a
variable-energy synchrocyclotron having a superconducting
electromagnetic structure. The particle beam output device may
comprise a beam spreader. The beam spreader comprises one or more
scanning magnets or one or more scattering foils
[0016] The example particle therapy system may comprise a
configurable collimator between the particle beam output device and
the patient. The configurable collimator may comprise leaves that
are controllable to define an edge to block a first part of the
particle beam from reaching the patient while collimating a second
part of the particle beam that passes to the patient. The
configurable collimator may be controllable to trim an area as
small as a single spot size of the particle beam.
[0017] The control system may be configured to provide automated
control over movement of the particle beam output device to
implement translational movement of the particle beam output device
from a first location to a second location to position the particle
beam for treatment of the irradiation target with the particle beam
and, following the treatment of the irradiation target with the
particle beam, to provide automated control over further movement
of the particle beam output device to implement translational
movement of the particle beam output device from the second
location to a third location to reposition the particle beam for
treatment of the irradiation target with the particle beam.
[0018] The control system may be configured to provide automated
control over movement of the particle beam output device to pivot
the particle beam output device from a first orientation to a
second orientation to position the particle beam for treatment of
the irradiation target with the particle beam and, following the
treatment of the irradiation target with the particle beam, to
provide automated control over further movement of the particle
beam output device to pivot the particle beam output device from
the second orientation to a third orientation to reposition the
particle beam for treatment of the irradiation target with the
particle beam.
[0019] The example particle therapy system may comprise a scanning
system comprising components to move the particle beam relative to
the irradiation target, with at least some of the components being
mounted for movement towards, and away from, the irradiation
target. The control system may be configured to provide automated
control of the at least some of the components to position the
particle beam for the treatment of the irradiation target with the
particle beam and, following the treatment of the irradiation
target with the particle beam, to provide automated control of the
at least some of the components to reposition the particle beam for
the additional treatment of the irradiation target with the
particle beam.
[0020] The example particle therapy system may comprise a carriage
on which the at least some of the components are mounted, with the
carriage being mounted to at least one track to enable movement
along a path of the particle beam. The carriage may be controllable
to move along the at least one track to control a size of a spot
produced by the particle beam. The carriage may be controllable to
move along the at least one track in coordination with movement of
at least one of the movable device or the treatment couch.
[0021] The movable device may comprise a rotatable gantry. The
movable device may comprise one or more robotic arms.
[0022] The example particle therapy system may comprise a scanning
system comprising components to move the particle beam relative to
the irradiation target, with the scanning components being mounted
on a carriage that is movable along a beamline of the particle
beam. The control system may be configured to provide automated
control of the carriage to position the particle beam for the
treatment of the irradiation target with the particle beam and,
following the treatment of the irradiation target with the particle
beam, to provide automated control of the carriage to reposition
the particle beam for the additional treatment of the irradiation
target with the particle beam.
[0023] An example method comprises supporting a patient containing
an irradiation target on a treatment couch, with the treatment
couch being configured for movement; mounting a particle beam
output device on a movable device for movement relative to the
treatment couch, with the particle beam output device for directing
output of a particle beam to treat the irradiation target;
providing automated control of at least one of the movable device
or the treatment couch to position at least one of the particle
beam or the irradiation target for treatment of the irradiation
target with the particle beam and, following treatment of the
irradiation target with the particle beam, providing automated
control at least one of the movable device or the treatment couch
to reposition at least one of the particle beam or the irradiation
target for additional treatment of the irradiation target with the
particle beam. The particle beam may be a proton beam.
[0024] An example particle therapy system comprises a treatment
couch to support a patient containing an irradiation target, with
the treatment couch being configured for movement; a particle beam
output device to direct output of a particle beam, with the
particle beam output device being arranged for movement relative to
the treatment couch; and a control system to control positioning of
the particle beam output device and the treatment couch using
degrees of freedom that exceed isocentric rotation of the particle
beam output device and the treatment couch. The example particle
therapy system may comprise one or more of the following features,
either alone or in combination.
[0025] The particle beam output device may comprise scanning
components to scan the particle beam relative to the irradiation
target, with the scanning components comprising one or more
scanning magnets. The control system may be configured to control a
position of the particle beam by controlling operation of one or
more of the scanning components The control system may be
configured to control positioning of the particle beam output
device and the treatment couch absent user intervention. The
control system may be configured to control positioning of the
particle beam output device and the treatment couch automatically
for multiple beam fields. The particle beam output device may be
controllable to move linearly between a first position and a second
position. The particle beam output device may be controllable to
pivot relative to the treatment couch. The particle beam output
device may be controllable to rotate relative to the treatment
couch. The particle beam output device may comprise a particle
accelerator. The particle beam output device may be configured to
produce a beam field of 30 cm by 30 cm or less.
[0026] An example particle therapy system comprises a treatment
couch to support a patient containing an irradiation target, with
the treatment couch being configured for movement; an apparatus to
direct output of a particle beam; a movable device on which the
apparatus is mounted to move the apparatus relative to the
treatment couch, with the apparatus being mounted relative to the
treatment couch to produce a beam field of 30 cm by 30 cm or less;
and a control system to provide automated positioning of at least
one of the apparatus or the treatment couch for treatment of a
first part of the irradiation target with the particle beam and,
following the treatment of the first part of the irradiation target
with the particle beam, to provide automated repositioning at least
one of the apparatus or the treatment couch for treatment of a
second part of the irradiation target with the particle beam. The
example particle therapy system may comprise one or more of the
following features, either alone or in combination.
[0027] At least one of the automated positioning or the automated
repositioning processes may comprise translational movement. The
apparatus may comprise a beam spreader to deliver the particle beam
via a transmission channel. The apparatus may comprise a particle
accelerator configured to generate the particle beam. The apparatus
may be mounted to produce a beam field of 20 cm by 20 cm or less.
The apparatus may comprise a synchrocyclotron having a weight that
is within a range of 5 tons to 30 tons and that occupies a volume
of less than 4.5 cubic meters.
[0028] The example particle therapy system may comprise a collision
avoidance system to detect positions of one or more components of
the particle therapy system and to provide information about
positions to the control system. The control system may be
configured to control operation of the one or more components based
on the information. The control system may be configured to provide
automated control of the particle beam to control intensities of
the particle beam so that cumulative intensities at points of
overlap between a particle beam for a first beam field and a
particle beam for a second beam field remain within a range of a
target beam intensity.
[0029] Two or more of the features described in this disclosure,
including those described in this summary section, may be combined
to form implementations not specifically described herein.
[0030] Control of the various systems described herein, or portions
thereof, may be implemented via a computer program product that
includes instructions that are stored on one or more non-transitory
machine-readable storage media, and that are executable on one or
more processing devices (e.g., microprocessor(s),
application-specific integrated circuit(s), programmed logic such
as field programmable gate array(s), or the like). The systems
described herein, or portions thereof, may be implemented as an
apparatus, method, or electronic system that may include one or
more processing devices and computer memory to store executable
instructions to implement control of the stated functions.
[0031] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other features
and advantages will be apparent from the description and drawings,
and from the claims.
DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a cut-away, side view of components of an example
synchrocyclotron that may be used in a particle therapy system.
[0033] FIG. 2 is a side view of example components that may be used
to implement scanning in the particle therapy system.
[0034] FIG. 3 is a perspective view of example components that may
be used to implement scanning in the particle therapy system.
[0035] FIG. 4 is a side view of an example scanning magnet that may
be part of the scanning components.
[0036] FIG. 5 is a perspective view of an example scanning magnet
that may be part of the scanning components.
[0037] FIG. 6 is a perspective view of an example range modulator,
which is a type of energy degrader that may be part of the scanning
components.
[0038] FIG. 7 is a perspective view showing an example of movement
of plates that may be implemented in the range modulator.
[0039] FIG. 8 is a front view of components of an example
implementation of a particle therapy system from the perspective of
a treatment space.
[0040] FIG. 9 is a perspective view of components of another
example implementation of a particle therapy system.
[0041] FIG. 10 is a conceptualized perspective view of a beam
field.
[0042] FIG. 11 is a perspective view of components of the particle
therapy system of FIG. 8 from the perspective of a treatment
space.
[0043] FIG. 12 is a diagram showing a particle beam hitting an
irradiation target from different angles during intensity-modulated
proton therapy (IMPT).
[0044] FIG. 13 is a flowchart showing an example process for
automating treatment of a patient using a particle therapy
system.
[0045] FIG. 14 is a system diagram depicting a control system,
particle therapy system components, and a treatment planning system
(TPS).
[0046] FIG. 15 is a block diagram depicting, conceptually,
treatment across two different beam fields of a particle
accelerator.
[0047] FIG. 16 is a block diagram depicting overlap of particle
beams for two beam fields in an area of overlap of the two beam
fields.
[0048] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0049] Described herein are examples of particle therapy systems
that are configured to automate treatment (e.g., delivery of
particle beam) across sequential beam fields. Treatment furthermore
is not limited to patient or accelerator movement relative to a
single isocenter. Rather, in some implementations, components of
the system, including those that affect beam position and patient
position, may be computer-controlled to automate treatment at any
appropriate point in an irradiation target, including across beam
fields and without reference to an isocenter. Automating the
treatment process, and reducing reliance on isocentric treatment,
may provide for more treatment flexibility and support additional
reductions in the size of the particle therapy system.
[0050] An example of a particle therapy system that is configurable
to automate treatment in the manner described above is a proton or
ion therapy system. In some implementations, the components of the
proton therapy system that actually provide treatment, including
the particle accelerator itself in some cases, are located in a
single treatment room, called a proton center. In some
implementations, the proton center is 30 feet (ft) by 30 ft by 30
ft (30 ft.sup.3) or less in volume. In some implementations, the
proton center is 37 feet (ft) by 32 ft by 28 ft or less in volume.
In some implementations, a beam spreader (also referred to as a
"spreader") is mounted for delivery of proton therapy to the
patient. Examples of beam spreaders include, but are not limited
to, one or more scanning magnets, examples of which are described
herein, or one or more scattering foils. A scattering foil scatters
the particle beam to produce a dispersed beam for application to a
target in the patient. A scanning magnet moves a more concentrated
version of the particle beam in at least two dimensions across a
target in the patient.
[0051] The beam field produced by the beam spreader is based, at
least in part, on the distance between the beam spreader and an
isocenter in the patient. In this regard, the beam field (also
called the irradiation field) corresponds to a projection of
radiation--here a particle beam--from the spreader. A beam field
may be represented conceptually by a plane that defines the maximum
extent or range that a projection of a particle beam can move in
the X and Y directions relative to the irradiation target. The size
(e.g., the area) of a beam field may be based on the distance
between the beam spreader and an isocenter in the patient. In
implementations where the beam spreader includes one or more
scanning magnets, the size of the beam field may also be based on
the amount of current through the scanning magnets. That is, the
more current that passes through the scanning magnets, the more the
beam can be deflected, resulting in a larger beam field.
[0052] Because of the relatively small size of the proton center,
the size of the beam field is limited. That is, because the proton
center is relatively small, the distance between the beam spreader
and the patient on a treatment couch is relatively short. In some
implementations, the distance from the beam spreader to an
isocenter in the patient may be 2 meters (m) or less, 1.7 m or
less, 1.5 m, or less, 1 m or less, and so forth. As a result of
this relatively short distance, the size of the beam field is also
relatively small. For example, in some implementations, the size of
the beam field may be 30 centimeters (cm) by 30 cm or less, 20 cm
by 20 cm or less, and so forth. Also, large beam deflection angles
are often discouraged for treatment, further limiting the size of
the beam field.
[0053] The relatively small size of the beam field can affect
treatment if the irradiation target (e.g., a tumor in a patient)
exceeds the size of the beam field. For this reason, conventional
proton therapy providers attempt to increase their field size as
much as possible. By contrast, with the example compact system
described herein--in particular one that delivers proton therapy in
a single proton center--increasing the size of the beam field
beyond a certain limit may be difficult in some examples due to
physical limitations. Accordingly, the example systems described
herein are configured to automatically treat an irradiation target
using multiple beam fields. In some cases movement of the particle
beam and the target are in degrees of freedom that exceed
isocentric rotation of the particle accelerator or spreader and a
treatment couch, making it possible to treat different beam fields
automatically and, in some cases, absent user intervention.
[0054] The example particle therapy system includes a particle
accelerator--in this example, a synchrocyclotron--mounted on a
movable device. In some examples, the movable device is a gantry
that enables the accelerator to be rotated at least part-way, and
in some cases all the way, around a patient position to allow a
particle beam from the synchrocyclotron to hit any arbitrary target
in the patient. Any appropriate device, including a gantry, may be
used to hold the particle accelerator and to move the particle
accelerator in a rotational, translational, and/or pivotal motion
relative to the patient. For example, the particle accelerator may
be mounted to one or more tracks to enable motion relative to the
patient. In another example, the particle accelerator may be
mounted to one or more robotic arms to enable motion relative to
the patient. In any case, the particle therapy system described
herein is not limited to use with a gantry, to use with a
rotational gantry, or to use with the example gantry configurations
described herein. In some implementations, the beam spreader is
mounted to the synchrocyclotron and is movable therewith. In some
implementations, the beam spreader is mounted to the device--e.g.,
to the gantry--independent of the synchrocyclotron and is movable
in the manner that the synchrocyclotron is described as being
movable herein. The spreader is an example of a particle beam
output device in that it directs the beam to the patient. Other
examples of particle beam output devices are described herein
including, but not limited to, the particle accelerator itself (or
components thereof) which produces the particle beam and directs
the output thereof.
[0055] In some implementations, the example synchrocyclotron has a
high magnetic field superconducting electromagnetic structure. In
general, a superconductor is an element or metallic alloy which,
when cooled below a threshold temperature, loses most, if not all,
electrical resistance. As a result, current flows through the
superconductor substantially unimpeded. Superconducting coils,
therefore, are capable of conducting much larger currents in their
superconducting state than are ordinary wires of the same size.
Because of the high amounts of current that superconducting coils
are capable of conducting, magnets that employ superconducting
coils are capable of generating high magnetic (B) fields for
particle acceleration. Furthermore, because the bend radius of a
charged particle having a given kinetic energy is reduced in direct
proportion to an increase in the magnetic field applied to the
charged particle, a high magnetic field superconducting
electromagnetic structure enables the synchrocyclotron to be made
compact, e.g., relatively small and light. More specifically, the
higher the magnetic field used, the tighter the particle turn
radius may be, thereby allowing for a larger numbers of turns to be
made within a relatively small volume (that is, relative to larger,
non-superconducting synchrocyclotrons). As a result, a desired
particle energy--which increases with an increase in the number of
turns--can be achieved using a synchrocyclotron having a relatively
small size and weight. In some implementations, the
synchrocyclotron is configured to produce a particle beam having
sufficient energy to reach any arbitrary target within the patient
from any appropriate position in the proton center relative to the
patient.
[0056] By way of example, in some implementations, a maximum
magnetic field produced in the acceleration cavity of the
synchrocyclotron (e.g., at the center of the cavity) may be between
4 Tesla (T) and 20 T. In some implementations, the synchrocyclotron
weighs less than 40 Tons. For example, the synchrocyclotron may
have a weight that is within a range from 5 tons to 30 tons. In
some implementations, the synchrocyclotron occupies a volume of
less than 4.5 cubic meters. For example, the synchrocyclotron may
occupy a volume in a range from 0.7 cubic meters to 4.5 cubic
meters. In some implementations, the synchrocyclotron produces a
proton or ion beam having an energy level of at least 150 MeV. For
example, the synchrocyclotron may produce a proton or ion beam
having an output energy level that is within a range from 150 MeV
to 300 MeV, e.g., 230 MeV. Different implementations of the
synchrocyclotron may have different values or combinations of
values for size, volume, and energy level, including values not
stated. Advantageously, the compact nature of the synchrocyclotron
described herein allows the treatment to be performed in one room,
i.e., in the proton center.
[0057] In this regard, traditionally, particle accelerators,
including synchrocyclotrons, were considerably larger than the
example compact accelerators described herein. By making the
particle accelerator and the beamline (e.g., beam shaping)
components compact, in some examples it is possible to enable
operation of the system in closer patient proximity than has been
possible with some traditional systems. For example, the compact
size of the accelerator allows for mounting on the gantry (or other
appropriate device), thereby reducing the cost and complexity of
the whole system. But, in some examples, such a mounting may limit
the space available for beamline (e.g., nozzle) components, forcing
configuration of a relatively compact beamline. In some examples,
this is one reason why an energy degrader as described herein is
mounted in or on a nozzle that is relatively close to the patient,
and in turn, why a collimator, also mounted in or on the nozzle, as
described herein (which itself is compact) is used to keep beam
edges sharp.
[0058] In some implementations, as described herein, the nozzle is
mounted on an inner gantry that is within the sweep of the "outer"
gantry holding the particle accelerator, that moves in synchronism
with movement of the outer gantry, and that positions the nozzle to
receive output of the accelerator on the outer gantry. In some
implementations, the nozzle is mounted for movement on the inner
gantry relative to the patient, e.g., along a C-shaped track. In
some implementations, there may be no inner gantry, and all
components described herein as being mounted to the inner gantry or
to the nozzle are mounted to the outer gantry.
[0059] In some examples, the components mounted on the nozzle
closest to the patient (e.g., a collimator and energy degrader) may
present potential interference, so those components may be made
relatively small. But, the size of those components is related to
the treatable field size. That is, these smaller components may
also decrease the beam field size. In some cases, by enabling the
particle therapy system to perform treatment using multiple beam
fields, more compact beamline elements may be used. As a result, a
smaller nozzle, which may be positioned in even closer proximity to
the patient, may be used.
[0060] FIG. 1 shows a cross-section of components 10 of an example
superconducting synchrocyclotron that may be used in a particle
therapy system. In this example, components 10 include a
superconducting magnet 11. The superconducting magnet includes
superconducting coils 12 and 13. The superconducting coils are
formed, e.g., of multiple superconducting strands (e.g., four
strands or six strands) wound around a center strand which may
itself be superconducting or non-superconducting (e.g., copper).
Each of the superconducting coils 12, 13 is for conducting a
current that generates a magnetic field (B). The resulting magnetic
field is shaped by magnetic yokes 14, 15. In an example, a cryostat
(not shown) uses liquid helium (He) to maintain each coil at
superconducting temperatures, e.g., around 4.degree. Kelvin (K).
The magnetic yokes 14, 15 (or smaller magnetic pole pieces) are
located inside the cryostat, and define the shape of a cavity 16 in
which particles are accelerated. Magnetic shims (not shown) may
pass through the magnetic yokes or pole pieces to change the shape
and/or magnitude of the magnetic field in the cavity.
[0061] In some implementations, the particle accelerator includes a
particle source 17 (e.g., a Penning Ion Gauge--PIG source) to
provide an ionized plasma column to the cavity 16. Hydrogen gas, or
a combination of hydrogen gas and a noble gas, is ionized to
produce the plasma column. A voltage source provides a varying
radio frequency (RF) voltage to cavity 16 to accelerate pulses of
particles from the plasma column within the cavity. The magnetic
field in the cavity is shaped to cause particles to move orbitally
within the cavity. In some implementations, the maximum magnetic
field produced by the superconducting coils may be within the range
of 4 Tesla (T) to 20 T, as explained herein. The example
synchrocyclotron employs a magnetic field that is uniform in
rotation angle and falls off in strength with increasing radius. In
some implementations, such a field shape can be achieved regardless
of the magnitude of the magnetic field.
[0062] As noted, in an example, the particle accelerator is a
synchrocyclotron. Accordingly, the RF voltage is swept across a
range of frequencies to account for relativistic effects on the
particles (e.g., increasing particle mass) when accelerating
particles within the acceleration cavity. The magnetic field
produced by running current through the superconducting coils,
together with the shape of the cavity, causes particles accelerated
from the plasma column to accelerate orbitally within the cavity
and to increase in energy with an increasing number of turns.
[0063] In the example synchrocyclotron, a magnetic field
regenerator (not shown) is positioned near the outside of the
cavity (e.g., at an interior edge thereof) to adjust the existing
magnetic field inside the cavity to thereby change locations, such
as the pitch and angle, of successive orbits of the particles
accelerated from the plasma column so that, eventually, the
particles output to an extraction channel that passes through the
cryostat. The regenerator may increase the magnetic field at a
point in the cavity (e.g., it may produce a magnetic field "bump"
of about 2 Tesla or so at an area of the cavity), thereby causing
each successive orbit of particles at that point to proceed
outwardly toward the entry point of an extraction channel until the
particles reach the extraction channel. The extraction channel
receives, from the cavity, particles that have been accelerated
within the cavity, and outputs the received particles from the
cavity in a pulsed particle beam. The extraction channel may
contain magnets and other structures to direct the particle beam
out of the particle accelerator and towards a scanning or
scattering system.
[0064] As noted, the superconducting coils (called the main coils)
can produce relatively high magnetic fields. In an example
implementation, the maximum magnetic field generated by a main coil
(e.g., at the center of the acceleration cavity) may be within a
range of 4 T to 20 T or more. For example, the superconducting
coils may be used in generating magnetic fields at, or that exceed,
one or more of the following magnitudes: 4.0 T, 4.1 T, 4.2 T, 4.3
T, 4.4 T, 4.5 T, 4.6 T, 4.7 T, 4.8 T, 4.9 T, 5.0 T, 5.1 T, 5.2 T,
5.3 T, 5.4 T, 5.5 T, 5.6 T, 5.7 T, 5.8 T, 5.9 T, 6.0 T, 6.1 T, 6.2
T, 6.3 T, 6.4 T, 6.5 T, 6.6 T, 6.7 T, 6.8 T, 6.9 T, 7.0 T, 7.1 T,
7.2 T, 7.3 T, 7.4 T, 7.5 T, 7.6 T, 7.7 T, 7.8 T, 7.9 T, 8.0 T, 8.1
T, 8.2 T, 8.3 T, 8.4 T, 8.5 T, 8.6 T, 8.7 T, 8.8 T, 8.9 T, 9.0 T,
9.1 T, 9.2 T, 9.3 T, 9.4 T, 9.5 T, 9.6 T, 9.7 T, 9.8 T, 9.9 T, 10.0
T, 10.1 T, 10.2 T, 10.3 T, 10.4 T, 10.5 T, 10.6 T, 10.7 T, 10.8 T,
10.9 T, 11.0 T, 11.1 T, 11.2 T, 11.3 T, 11.4 T, 11.5 T, 11.6 T,
11.7 T, 11.8 T, 11.9 T, 12.0 T, 12.1 T, 12.2 T, 12.3 T, 12.4 T,
12.5 T, 12.6 T, 12.7 T, 12.8 T, 12.9 T, 13.0 T, 13.1 T, 13.2 T,
13.3 T, 13.4 T, 13.5 T, 13.6 T, 13.7 T, 13.8 T, 13.9 T, 14.0 T,
14.1 T, 14.2 T, 14.3 T, 14.4 T, 14.5 T, 14.6 T, 14.7 T, 14.8 T,
14.9 T, 15.0 T, 15.1 T, 15.2 T, 15.3 T, 15.4 T, 15.5 T, 15.6 T,
15.7 T, 15.8 T, 15.9 T, 16.0 T, 16.1 T, 16.2 T, 16.3 T, 16.4 T,
16.5 T, 16.6 T, 16.7 T, 16.8 T, 16.9 T, 17.0 T, 17.1 T, 17.2 T,
17.3 T, 17.4 T, 17.5 T, 17.6 T, 17.7 T, 17.8 T, 17.9 T, 18.0 T,
18.1 T, 18.2 T, 18.3 T, 18.4 T, 18.5 T, 18.6 T, 18.7 T, 18.8 T,
18.9 T, 19.0 T, 19.1 T, 19.2 T, 19.3 T, 19.4 T, 19.5 T, 19.6 T,
19.7 T, 19.8 T, 19.9 T, 20.0 T, 20.1 T, 20.2 T, 20.3 T, 20.4 T,
20.5 T, 20.6 T, 20.7 T, 20.8 T, 20.9 T, or more. Furthermore, the
superconducting coils may be used in generating magnetic fields
that are outside the range of 4 T to 20 T or that are within the
range of 4 T to 20 T but that are not specifically listed
herein.
[0065] In some implementations, such as the implementations shown
in FIG. 1, the relatively large ferromagnetic magnetic yokes 14, 15
act as returns for stray magnetic fields produced by the
superconducting coils. In some systems, a magnetic shield (not
shown) surrounds the yokes. The return yokes and the shield
together act to reduce stray magnetic fields, thereby reducing the
possibility that stray magnetic fields will adversely affect the
operation of the particle accelerator.
[0066] In some implementations, the return yokes and shield may be
replaced by, or augmented by, an active return system. An example
active return system includes one or more active return coils that
conduct current in a direction opposite to current through the main
superconducting coils. In some example implementations, there is an
active return coil for each superconducting main coil, e.g., two
active return coils--one for each main superconducting coil. Each
active return coil may also be a superconducting coil that
surrounds the outside of a corresponding main superconducting coil
concentrically.
[0067] As noted, current passes through the active return coils in
a direction that is opposite to the direction of current passing
through the main coils. The current passing through the active
return coils thus generates a magnetic field that is opposite in
polarity to the magnetic field generated by the main coils. As a
result, the magnetic field generated by an active return coil is
able to reduce at least some of the relatively strong stray
magnetic field resulting from a corresponding main coil.
[0068] By using an active return system, the relatively large
ferromagnetic magnetic yokes 14, 15 can be replaced with magnetic
pole pieces that are smaller and lighter. Accordingly, the size and
weight of the synchrocyclotron can be reduced further without
sacrificing performance. An example of an active return system that
may be used is described in U.S. Pat. No. 8,791,656 entitled
"Active Return System", the contents of which are incorporated
herein by reference.
[0069] At or near the output of the extraction channel of the
particle accelerator, there may be one or more beam shaping
elements, such as a scanning system and/or a scattering system.
Components of these systems may be mounted on, or otherwise
attached to, the nozzle for positioning relatively close to the
patient during treatment. In some implementations, however, beam
spreader(s) may be mounted closer to (e.g., on) the accelerator or
the outer gantry itself (e.g., mounted to the outer gantry in the
absence of an accelerator mounted there).
[0070] Referring to FIG. 2, in an example implementation, at the
output of extraction channel 20 of synchrocyclotron 21 (which may
have the configuration of FIG. 1) are example scanning components
22 that may be used to scan the particle beam across all or part of
an irradiation target. FIG. 3 also shows examples of the components
of FIG. 2. These include, but are not limited to, a scanning
magnet(s) 24, an ion chamber 25, an energy degrader 26, and a
configurable collimator 28. Other components that may be down-beam
of the extraction channel are not shown in FIG. 2 or 3, including,
e.g., one or more scatterers for changing beam spot size.
[0071] In an example operation, scanning magnet 24 is an example
beam spreader, and is controllable in two dimensions (e.g.,
Cartesian XY dimensions) to position the particle beam in those two
dimensions, and to move the particle beam across at least a part
(e.g., a cross-section) of an irradiation target. Ion chamber 25
detects the dosage of the beam and feeds-back that information to a
control system to adjust beam movement. Energy degrader 26 is
controllable to move material (e.g., one or more individual plates)
into, and out of, the path of the particle beam to change the
energy of the particle beam and therefore the depth to which the
particle beam will penetrate the irradiation target. In this way,
the energy degrader can position the particle beam at a depth-wise
layer of an irradiation target, e.g., to the layer. In some
implementations, the energy degrader uses wedges or other types of
structures instead of, or in addition to, plates. For example,
energy degrader 26 may be controllable to move material (e.g., one
or more individual wedges) into, and out of, the path of the
particle beam to change the energy of the particle beam and
therefore the depth to which the particle beam will penetrate the
irradiation target.
[0072] In some implementations, there may be different energy
degraders having different sizes, e.g., plates or wedges having
different areas. In some implementations, the control system
described herein may swap, in and out of the beam field,
differently-sized energy degraders based on the beam field
size.
[0073] FIGS. 4 and 5 show views of an example scanning magnet 24.
In this example implementation, scanning magnet 24 includes two
coils 41, which control particle beam movement in the X direction,
and two coils 42, which control particle beam movement in the Y
direction. Control is achieved, in some implementations, by varying
current through one or both sets of coils to thereby vary the
magnetic field(s) produced thereby. By varying the magnetic
field(s) appropriately, the particle beam can be moved in the X
and/or Y direction across the irradiation target. The scanning
magnet(s) may be leveraged to control the location and/or direction
of the particle beam in the automated treatment process described
herein.
[0074] In some implementations, the scanning magnet is not movable
physically relative to the particle accelerator. In some
implementations, the scanning magnet may be movable physically
relative to the particle accelerator (e.g., in addition to the
movement provided by the gantry). In some implementations, the
scanning magnet may be controllable to move the particle beam
continuously so that there is uninterrupted motion of the particle
beam over at least part of, and possibly all of, a layer of an
irradiation target being scanned. In some implementations, the
scanning magnets are controllable at intervals or specific times.
In some implementations, there may be two or more different
scanning magnets to position the particle beam, and to control all
or part movement of a particle beam in the X and/or Y directions
during scanning. In some implementations, scanning magnet 24 may
have an air core, a ferromagnetic (e.g., an iron) core, or a core
that is a combination of air and ferromagnetic material.
[0075] Referring back to FIG. 2, a current sensor 27 may be
connected to, or be otherwise associated with, scanning magnet 24.
For example, the current sensor may be in communication with, but
not connected to, the scanning magnet. In some implementations, the
current sensor samples current applied to the magnet, which may
include current to the coil(s) for controlling beam scanning in the
X direction and/or current to the coil(s) for controlling beam
scanning in the Y direction. The current sensor may sample current
through the magnet at times that correspond to the occurrence of
pulses in the particle beam or at a rate that exceeds the rate that
the pulses occur in the particle beam. In the latter case, the
samples, which identify the magnet current, are correlated to
detection of the pulses by the ion chamber described below. For
example, the times at which pulses are detected using the ion
chamber may be correlated in time to samples from the current
sensor, thereby identifying the current in the magnet coil(s) at
the times of the pulses. Using the magnet current, it thus may be
possible to determine the location on the irradiation target (e.g.,
on a depth-wise layer of the irradiation target) where each pulse,
and thus dose of particles, was delivered. The location of the
depth-wise layer may be determined based on the configuration of
the energy degrader (e.g., the number of plates) in the beam
path.
[0076] During operation, the magnitude(s) (e.g., value(s)) of the
magnet current(s)) may be stored for each location at which a dose
is delivered, along with the amount (e.g., intensity) of the dose.
A computer system, which may be either on the accelerator or remote
from the accelerator and which may include memory and one or more
processing devices, may correlate the magnet current to coordinates
within the radiation target, and those coordinates may be stored
along with the amount of the dose. For example, the location may be
identified by depth-wise layer number and Cartesian XY coordinates
or by Cartesian XYZ coordinates (with the depth-wise layer
corresponding to the Z coordinate). In some implementations, both
the magnitude of the magnet current and the coordinate locations
may be stored along with the dose at each location. The foregoing
information may be stored in memory either on, or remote from, the
accelerator. This information may be used during scanning to apply
multiple doses of the same or of different amounts to the same
locations to achieve target cumulative doses, including at areas of
overlap between adjacent/sequential beam fields, as described
herein.
[0077] In some implementations, ion chamber 25 detects dosage
(e.g., one or more individual doses) applied by the particle beam
to positions on an irradiation target by detecting the numbers of
ion pairs created within a gas caused by incident radiation. The
numbers of ion pairs correspond to the dose provided by the
particle beam. That information is fed-back to the computer system
and stored in memory along with the time that the dose is provided.
This information may be correlated to, and stored in association
with, the location at which the dose was provided and/or the
magnitude of the magnet current at that time, as described
above.
[0078] In some implementations, the scanning system is run open
loop, in which case, by controlling the scanning magnet(s), the
particle beam is moved freely and uninterrupted across an
irradiation target so as to substantially cover the target with
radiation. As the radiation is delivered, the dosimetry controlled
by the particle therapy control system records (e.g., stores) the
amount of the radiation per location and information corresponding
to the location at which the radiation was delivered. The location
at which the radiation was delivered may be recorded as coordinates
or as one or more magnet current values, and the amount of the
radiation that was delivered may be recorded as dosage in grays.
Because the system is run open loop, the delivery of the radiation
is not synchronized to the operation of the particle accelerator
(e.g., to its radio frequency (RF) cycle). Locations on the target
where insufficient dose has been deposited can be treated with the
particle beam any appropriate number of times until a desired
dosage is reached. Different treatments of the same location may be
from the same beam angle (e.g., from the same projection/beam
field) or from different beam angles (projections/beam fields) as
is the case intensity-modulated proton therapy (IMPT) described
herein.
[0079] Configurable collimator 28 may be located down-beam of the
scanning magnets and down-beam of the energy degrader, as shown in
FIGS. 2 and 3. The configurable collimator may trim the particle
beam on a spot-by-spot basis during movement of the particle beam
during scanning. For example, the configurable collimator may
include sets of leaves that face each other, and that are movable
into and out of carriages to create an aperture shape. Parts of the
particle beam that exceed the aperture shape are blocked, and do
not pass to the patient. The parts of the beam that pass to the
patient are at least partly collimated, thereby providing a beam
with a relatively precise edge. In an example, each set of leaves
in the configurable collimator is controllable to define an edge
that is movable into a path of the particle beam such that a first
part of the particle beam on a first side of the edge is blocked by
the multiple leaves and such that a second part of the particle
beam on a second side of the edge is not blocked by the multiple
leaves. The leaves in each set are individually controllable during
scanning to trim an area as small as a single spot, and can also be
used to trim larger multi-spot areas.
[0080] FIG. 6 shows a range modulator 60, which is an example
implementation of energy degrader 26. In some implementations,
range modulator 60 may be located down-beam of the scanning magnets
between the configurable collimator and the patient. In some
implementations, such as that shown in FIG. 6, the range modulator
includes a series of plates 61. The plates may be made of one or
more of the following example materials: polycarbonate, carbon,
beryllium or other material of low atomic number. Other materials,
however, may be used in place of, or in addition to, these example
materials.
[0081] One or more of the plates is movable into, or out of, the
beam path to thereby affect the energy of the particle beam and,
thus, the depth of penetration of the particle beam within the
irradiation target. That is, each plate allows the beam to pass
but, as a result of passing through the plate, the energy of the
beam is decreased by an amount that is based on the geometry (e.g.,
thickness) and the composition (e.g., material) of the plate. In an
example, the more plates that are moved into the path of the
particle beam, the more energy that will be absorbed by the plates,
and the less energy the particle beam will have. Conversely, the
fewer plates that are moved into the path of the particle beam, the
less energy that will be absorbed by the plates, and the more
energy the particle beam will have. Higher energy particle beams
typically penetrate deeper into the irradiation target than do
lower energy particle beams. In this context, "higher" and "lower"
are meant as relative terms, and do not have any specific numeric
connotations.
[0082] Plates are moved physically into, and out of, the path of
the particle beam. For example, as shown in FIG. 7, a plate 70
moves along the direction of arrow 72 between positions in the path
of the particle beam 73 and outside the path of the particle beam.
The plates are computer-controlled. Generally, the number of plates
that are moved into the path of the particle beam corresponds to
the depth at which scanning of an irradiation target is to take
place. Thus, the particle beam can be positioned into the interior
of a target by appropriate control of the plates.
[0083] By way of example, the irradiation target can be divided
into cross-sections or depth-wise layers, each of which corresponds
to an irradiation depth. One or more plates of the range modulator
can be moved into, or out of, the beam path to the irradiation
target in order to achieve the appropriate energy to irradiate each
of these cross-sections or depth-wise layers of the irradiation
target. The range modulator may be stationary relative to the
particle beam during scanning of a part of (e.g., cross-section of)
an irradiation target or the plates of the range modulator may move
during scanning. For example, the particle beam may track movement
of one or more plates into, or out of, the beam field (also called
the irradiation field) during the scanning process.
[0084] Referring back FIG. 2, assembly 30, which includes, e.g.,
the ion chamber, the energy degrader, and the configurable
collimator, may be mounted, or otherwise coupled, to carriage 23.
In some implementations, carriage 23 is mounted to one or more
tracks--in this example, to two tracks 29a, 29b--for movement
relative to the irradiation target. In some examples, the carriage
may be part of, or mounted to, the nozzle, thereby enabling some
components of the scanning system to be moved towards, or away
from, the patient. In some implementations, carriage 23 may be
mounted using different mechanisms or in a different configuration
for movement relative to the irradiation target. Movement may be
along the beamline, e.g., along a path of the particle beam. This
movement enables additional control over positioning of the
particle beam--and thus an additional degree of freedom--to support
treatment across, and irrespective of, beam fields and any
isocenters.
[0085] Movement also will allow these components to be moved away
from a patient on the treatment couch to allow the nozzle and/or
patient to be moved automatically for the next projection/beam
field to be treated. Then, the nozzle can be moved back toward the
patient for the next beam field.
[0086] Moving the collimator and energy degrader towards, or away
from, the irradiation target affects the distance that the particle
beam travels through the air and, thus, the size of a spot of the
particle beam in the irradiation target. That is, passage through
air can cause the beam spot size to increase. Accordingly, moving
the carriage away from the irradiation target increases the
distance that the particle beam travels through the air, thus
increasing the spot size. Conversely, moving the carriage towards
the irradiation target decrease the distance that the particle beam
travels through the air, thus decreasing the spot size. In some
implementations, carriage 23 is controllable to move in
coordination with movement of the gantry and/or the treatment couch
as described herein to position the particle beam for treatment,
and to implement treatment in close proximity to the patient.
[0087] Some components of the scanning system, including the energy
degrader and the configurable collimator, may be mounted on, or
coupled to, a nozzle 81 of the particle therapy system's inner
gantry 80 (see FIG. 8), and may be controlled by a control system,
such as one or more computing devices (see, e.g., FIG. 14) that
also controls operation of other components of the particle therapy
system. FIG. 9 shows another implementation of a particle therapy
system having an inner gantry 90 with a nozzle 91 on which some
components of the scanning system, including the energy degrader
and the configurable collimator (but, in some cases, not the
scanning magnet(s)), may be mounted. In both examples, the nozzle
is movable along a track of the inner gantry (80 or 90) relative to
the patient and the particle accelerator, and is extensible
towards, and retractable away from, the patient, thereby also
extending and retracting the components mounted thereon.
[0088] Operation of the range modulator may be coordinated with,
and controlled with, operation of other scanning components, the
particle accelerator, and the gantries described herein to
implement automated particle therapy treatment and variations
thereof. For example, the range modulator may be used to position
the particle beam in a depth-wise (e.g., Cartesian Z) dimension
relative to an irradiation target, and other scanning components,
such as the beam spreader--e.g., the scanning magnet(s), may be
used to position the particle beam in two other dimensions relative
to the irradiation target that are orthogonal to the depth-wise
dimension (e.g., the Cartesian X,Y dimensions). Positioning using
the scanning components and other movable parts of the system
supports automated, multiple-field treatment particle therapy that
may or may not be isocentric. In cases where a variable-energy
synchrocyclotron is used, control over beam energy, and thus beam
depth-wise position, may be implemented in the accelerator
itself.
[0089] As noted, the particle beam passes from the range modulator,
through the configurable collimator, to the patient. Passage
through air can cause the beam spot size to increase. The longer
that the beam passes through air, the greater this spot size
increase may be. Accordingly, in some implementations, it is
advantageous to reduce the maximum distance that the beam can pass
through the air. As explained above, in some examples, the
components mounted on the nozzle closest to the patient (e.g., a
collimator and energy degrader) may reduce the amount that the beam
passes through the air. However, in some examples, because of their
proximity to the patient, those components may be made relatively
small. The size of those components is related to the treatable
field size. That is, these smaller components may result in a
relatively smaller beam field size.
[0090] As described, the beam field (also called the irradiation
field) is based on a projection of radiation from a beam spreader.
A beam field may be represented conceptually by a plane that
defines the maximum extent or range that a projection of a particle
beam can move in the X and Y directions relative to the irradiation
target. For example, FIG. 10 shows a beam field 100 in front of an
irradiation target 101. The target is depicted in dashed lines to
indicate that it is behind the beam field. Although a rectangular
plane is shown, the beam field may have any appropriate shape. Due
to physical system limitations, the particle beam produced by the
synchrocyclotron is movable across, but not beyond, the borders of
the beam field. As noted, reduced size of the nozzle enables the
reduction in the air gap, but also may make the beam field smaller
due to the presence of smaller components.
[0091] In some situations, the beam field may be smaller than the
irradiation target to be treated (which is not the case in FIG. 10,
but see, e.g., FIGS. 15 and 16 described below). Accordingly, in
some examples, the processes described herein automate movement of
components of the particle therapy system in order to treat the
entire irradiation target using multiple beam fields without
requiring manual accelerator reconfiguration, manual spreader
reconfiguration, and/or manual patient repositioning. Treatment
near the boundaries using two or more beam fields may be
computer-controlled based on instructions received from a TPS using
beam fields near the boundaries. Such treatment may also be
independent of any isocenter location(s). Example implementations
are described in more detail below.
[0092] FIGS. 8 and 11 show parts an example of a particle therapy
system 82 containing a particle accelerator mounted on a gantry--in
this example, a superconducting synchrocyclotron having a
configuration described herein is used. In some implementations,
the gantry is steel and has two legs (not shown) mounted for
rotation on two respective bearings that lie on opposite sides of a
patient. The gantry may include a steel truss, connected to each of
its legs, that is long enough to span a treatment area in which the
patient lies and that is attached at both ends to the rotating legs
of the gantry. The particle accelerator may be supported by the
steel truss. An example of a gantry configuration that may be used
is described in U.S. Pat. No. 7,728,311 entitled "Charged Particle
Radiation Therapy", the contents of which are incorporated herein
by reference.
[0093] FIG. 9 shows an example of the gantry configuration
described in U.S. Pat. No. 7,728,311, and includes components of an
alternative implementation of a particle therapy system that is
controllable in the manner described herein to produce automated
treatment. The example particle therapy system of FIG. 9 includes
an inner gantry 90 having a nozzle 91, a treatment couch 92, and a
particle accelerator 93 (e.g., a synchrocyclotron of the type
described herein) mounted on an outer gantry 94 for rotation at
least part-way around the patient to deliver radiation to target(s)
in the patient. Treatment couch 92 is controllable and configured
to rotate and to translate the patient in the manner described
herein.
[0094] In the example of FIG. 9, particle accelerator is also
mounted to outer gantry 94 also to enable linear movement (e.g.,
translational movement) of the particle accelerator in the
directions of arrow 95 along arms 96. Thus, the accelerator is
movable, relative to the treatment couch and thus the patient, from
a first location along arms 96, to a second location along arms 96,
to a third location along arms 96, and so forth in order to
position the accelerator, and thus the beam, for treatment. This
translational movement may be controlled by the control system
described herein, and used as an additional degree of freedom for
positioning the particle beam in the automated particle therapy
system described herein. Although single-dimensional translational
movement (along arrow 95) is shown in FIG. 9, the particle therapy
system may be configured for two-dimensional translational
movement, and/or three dimensional-translational movement as well
(e.g., along the X, Y, and Z directions of a Cartesian coordinate
system).
[0095] As also shown in FIG. 9, the particle accelerator 93 may be
connected to a gimbal 99 for pivoting motion relative to the
gantry. This pivoting motion may be used to position the
accelerator, and thus the beam, for treatment. This pivoting
movement may be controlled by the control system described herein,
and may be used as one or more additional degrees of freedom for
positioning the particle beam in the automated particle therapy
system described herein. In some implementations, pivoting may
enable the accelerator to move from a first orientation, to a
second orientation, to a third orientation, and so forth during
automated treatment. The particle accelerator may be mounted to
enable pivoting relative to the patient in one, two, and/or three
dimensions.
[0096] As described herein, in some implementations, rather than
mounting the entire particle accelerator to the outer gantry (or
other device), the spreader alone may be mounted in lieu of, or in
addition to, the accelerator, and the spreader alone or in
combination with the accelerator may be moved relative to the
irradiation target. In cases where the spreader is mounted alone,
the spreader may be moved in the same way as the accelerators
described herein, e.g., linearly (translation), rotationally,
and/or pivotally. Control over beam positioning may be implemented
as described herein by controlling movement of the spreader mounted
thereon in the manner described herein.
[0097] The example particle therapy system implementations shown in
FIGS. 8 and 11 may also mount the particle accelerator so that the
particle accelerator is capable of translational motion in one,
two, and/or three dimensions relative to the patient. The example
particle therapy system implementations shown in FIGS. 8 and 11 may
also mount the particle accelerator so that the particle
accelerator is capable of pivoting relative to the patient in one,
two, and/or three dimensions.
[0098] In the example of FIGS. 8 and 11, the patient is located on
a treatment couch 84. In this example, treatment couch 84 includes
a platform that supports the patient. The platform also may include
one or more restraints (not shown) for holding the patient in place
and for keeping the patient substantially immobile during movement
of the couch and during treatment. The platform may, or may not, be
padded and/or have a shape (e.g., an indentation) that corresponds
to the shape of part of the patient. For example, prior to
treatment, the patient may be placed in a mold that conforms to the
contours of the back half of the patient, and the resulting molded
structure may be incorporated into the platform of the treatment
couch. A mold, such as this, may reduce patient motion during
movement of the treatment couch including, but not limited to,
during treatment.
[0099] The treatment couch may include a movement mechanism to move
the treatment couch automatically from one position in the
treatment space (e.g., the proton center where particle therapy
treatment is performed) to another position in the treatment space.
The different positions may be different rotational positions,
different physical locations (e.g., a translational movement from
one physical location to another physical location), or a
combination of rotational and translational positions. For example,
the movement mechanism may include a robotic arm 85 that is
controllable to move the couch in six degrees of freedom.
[0100] Movement of the treatment couch is automated and occurs
while the patient remains in place on the couch. For example, the
treatment couch, with the patient thereon, may be moved between
different treatment positions. In some implementations, the patient
does not move off of the treatment couch during movement between
treatment positions. For example, the patient may be situated on
the treatment couch prior to treatment; the couch may be moved into
a first position for treatment of a first part of the patient; the
patient may be treated at the first position; the couch may be
moved to a second, different position for treatment of a second,
different part of the patient while the patient remains situated on
the couch; the patient may be treated at the second position; the
couch may be moved to a third, still different position for
treatment of a third, still different part of the patient while the
patient remains situated on the couch; and so forth until treatment
ends. Any appropriate number of couch movements and treatments may
be implemented, all while the patient remains on the treatment
couch and, in some cases, without human intervention. The different
"parts" of the patient to be treated may be, for example, different
tumors, different areas of one tumor, or the same areas of one
tumor, and may be treated from different angles as is the case
during intensity-modulated proton therapy. ("IMPT").
[0101] In this regard, during IMPT, the particle beam is projected
at the irradiation target from different directions so that a
percentage of the overall dose is delivered from each direction. As
a result, the amount of dose delivered to volumes outside of the
irradiation target can be reduced. For example, FIG. 12 shows a
particle beam 120 applied to the irradiation target 121 from three
different angles. In this example, dosage is cumulative, so 1/3 of
the total dose may be applied from one angle; 1/3 of the total dose
may be applied from another angle; and 1/3 of the total dose may be
applied from yet another angle. That is, the particle beam may be
scanned at angle 123 across a portion of a beam field in a plane
angled relative to horizontal 128 to apply 1/3 of the dose; the
particle beam may be scanned at angle 124 across a portion of a
beam field in another plane angled relative to horizontal 128 to
apply 1/3 of the dose; and the particle beam may be scanned at
angle 125 across a portion of a beam field in still another plane
angled relative to horizontal 128 to apply 1/3 of the dose. As a
result, the amount of radiation applied to surrounding tissue 127
is spread out at the appropriate angles, thereby reducing the
chances that surrounding tissue will be exposed to harmful amounts
of radiation. Even though only three are shown, any appropriate
number of angles and appropriate dosage per angle may be
employed.
[0102] Referring to FIGS. 8, 9, and 11, the inner gantry may be
configured to move relative to the treatment couch to direct output
of the beam toward the patient. In these examples, the inner gantry
is C-shaped, and its movement coincides with movement of the
"outer" gantry, on which the synchrocyclotron is mounted. As
explained, the inner gantry includes a nozzle, on which one or more
beamline components (e.g., the range modulator and configurable
collimator) are mounted to shape and otherwise adjust the beam. In
some implementations, the inner gantry supports sub-millimeter beam
positioning. In some implementations, there is no inner gantry, and
all components described herein as being mounted on the inner
gantry may be mounted to the accelerator or to the outer
gantry.
[0103] In some implementations, some or all movement of the
treatment couch occurs while the patient remains in place on the
couch. As explained, the treatment couch, with the patient thereon,
may be moved automatically between treatment positions. In some
implementations, the particle therapy system captures images of the
patient between treatments in order to direct the treatment to the
appropriate locations within the patient. In some implementations,
these images are captured while the patient is on the treatment
couch. For example, referring to the process of FIG. 13, the
patient may be situated (130) on the treatment couch prior to
treatment; the couch may be moved (131) into a first position for
treatment of the irradiation target or a portion of the irradiation
target within the patient with a first beam field; images of the
patient at the first position may be captured (132) while the
patient is on the treatment couch; and the patient may be treated
(133) at the first position based on the images. If additional
treatments are to be performed (134), the couch may be moved to a
second, different position for treatment of the irradiation target
or a portion thereof with a second beam field while the patient
remains situated on the couch; images of the patient at the second
position may be captured while the patient is on the treatment
couch; the patient may be treated at the second position based on
the captured images; the couch may be moved to a third, still
different position for treatment of the irradiation target or a
portion thereof with a third beam field while the patient remains
situated on the couch; images of the patient at the third position
may be captured while the patient is on the treatment couch; the
patient may be treated at the third position based on the captured
images; and so forth until treatment ends. In some implementations,
a sequencing that is different than that presented above may be
employed or different patient position tracking techniques than
those described may be used. In some implementations, imaging
following each treatment is not required.
[0104] In some implementations, the particle therapy system is
configured to determine the location of an irradiation target, such
as a tumor. The initial location and mapping of the irradiation
target (e.g., the tumor) may be obtained in a pre-treatment imaging
operation, which may occur inside or outside the proton center. In
some implementations, the patient may remain on the couch from
initial imaging through treatment, including repositioning during
treatment, as explained with respect to FIG. 13. Furthermore, in
some implementations, the entire process, from initial imaging to
final treatment, is automated, eliminating or, at least, reducing
the need for human intervention.
[0105] In some implementations, the pre-treatment imaging operation
may be performed using an imaging system, such as a
three-dimensional (3D) imaging system. In some implementations, the
3D imaging system is a computed tomography (CT) system; however, in
other implementations, different types of imaging systems may be
used instead of, or in addition to, a CT system. In operation,
images may be captured at different points in time in order to
enable tracking of movement of a fiducial due, e.g., to patient
movement, such as breathing or the like. In this context, a
fiducial includes a structure that is internal or external to the
patient, that can be identified in an image captured by the imaging
system, and that can be used to determine the location of an
irradiation target within the patient.
[0106] In the CT example, the image may include internal anatomical
structures, such as organs, tumors, and bones, any of which may be
an irradiation target (or fiducial, as described below). The
imaging system captures one or more images of the patient, or a
selected part of the patient, typically the part(s) of the patient
where proton therapy is to be applied. In some implementations, the
treatment couch may include one or more fiducials arranged thereon.
Examples of fiducials may include, but are not limited to, metal or
other material that shows-up on images, such as CT images. The
fiducials may be arranged at areas around the patient, e.g., at
and/or around parts of the patient where proton therapy is to be
applied. In some implementations, at least three fiducials are
arranged relative to the patient to enable use of a triangulation
process to locate the irradiation target in both the CT image and
the treatment space. In some implementations, CT images may be used
to identify structural elements of a person's anatomy, such as
teeth, bone, or the like, and to designate those structural
elements as fiducials. In some implementations, fiducials may be a
combination of any two or more of the foregoing, e.g., anatomical
structures and/or structural elements secured to the treatment
couch, to the patient, to a frame, or the like.
[0107] In the CT example, images are 3D so that, either alone or in
combination, the images provide information about the location of
the fiducials and the location of the irradiation target (e.g., the
tumor) in 3D. This information is indicative of the relative
positions of the fiducials and the irradiation target, and the
angles and distances between individual fiducials and between
individual fiducials and the radiation target. In some
implementations, the position information is obtained by
identifying the fiducials and the irradiation target in the 3D
image(s), and by analyzing the image(s) to determine the locations
of the fiducials and the size, shape, and location of the
irradiation target based on the locations of the fiducials (and, in
some cases, based on the size and/or shape of the fiducials). This
information may be stored in computer memory and used during
treatment in order to identify the location of the target in the
treatment space (the "real world").
[0108] Following initial imaging using the CT system, the patient
may be moved to the treatment position. The treatment couch may
move automatically while the patient is on the couch, or the
patient may move to a new treatment couch. The location to which
the treatment is to be applied is determined, in part, based upon
the 3D image(s) captured by the CT system (in this example).
[0109] Referring to FIG. 8, one or more treatment site (proton
center) imaging systems 86, such as an X-ray system, are controlled
to capture one or more images at the treatment position in the
treatment space. This treatment site imaging system may be used
alone, or in combination with, a computing system to detect
locations of the fiducials, and thus the irradiation target, in the
treatment space. The locations of the fiducials are detected
relative to one or more reference points in a coordinate system
that defines the treatment space. In other words, the treatment
space (e.g., the proton center) may be defined within a 3D
coordinate system, and the locations of the fiducials may be
identified by coordinates in that 3D coordinate system.
[0110] For example, the images from the treatment site imaging
system (e.g., X-ray images) may be analyzed to determine the
locations of the fiducials in a 3D XYZ Cartesian coordinate system
that defines the treatment space. One or more images of the
fiducials taken by the imaging system may be analyzed to identify
where, in the 3D coordinate system of the treatment space, the
fiducials are located. The resulting coordinates of the fiducials
in that coordinate system may be stored, e.g., in computer memory
on a computer system (not shown).
[0111] The locations of the fiducials in the 3D coordinate system
of the treatment space are aligned to the locations of the
fiducials in the 3D CT image(s). This may be done automatically by
a computer system using a virtual simulation (e.g., rendering) of
the treatment space. For example, the actual locations of the
fiducials may be identified in the simulation, and the fiducials
from the 3D CT image, along with other structures from the CT
image, may be placed at corresponding points in the simulation. By
placing the fiducials and other structures from the CT image in the
3D coordinate system of the treatment space, it is possible to
identify the location of the irradiation target in that same
space.
[0112] More specifically, the locations of the fiducials in the
treatment space (e.g., the 3D coordinate system of the treatment
space) are known, and the fiducials and structures, including the
irradiation target, from the 3D CT image are mapped into the 3D
coordinate system in the simulation. As part of the mapping, the
fiducials from the CT image are aligned to the locations of the
fiducials in the 3D coordinate system of the treatment space.
Furthermore, the location of the irradiation target relative to the
fiducials is known from the 3D CT image. For example, the distances
and angles of the irradiation target relative to each fiducial are
known. Given this information, the location and orientation of the
irradiation target in the 3D coordinate system of the treatment
space can be determined. This information is used to direct the
particle beam to the irradiation target.
[0113] The foregoing process of locating (e.g., by X-ray) fiducials
in the 3D coordinate system of the treatment space and correlating
those fiducials to those found in the original CT image(s) may be
automated and repeated each time the treatment couch supporting the
patient is moved within the treatment space. In some
implementations, after the images are taken for a position, because
the process may be under computer control and patient positioning
will be monitored to confirm that the patient has not moved, new
images may not need to be captured at each new position to which
the patient is moved. For example, accuracy of the treatment couch
motion and immobilization of the patient may be relied upon to
determine positions at new locations.
[0114] In this regard, the treatment couch may be moved
automatically between treatment positions in order to treat
different parts of the patient or to treat the patient from
different angles, as in the case in IMPT. In some implementations,
for each new position, a new image is captured, e.g., by an X-ray
system, and is analyzed relative to the original CT image(s). The
resulting position information identifies the location to be
treated in the real world space, e.g., in the 3D coordinate system
of the treatment space (e.g., the proton center). Knowing the
location of the target, various components of the proton therapy
system can be controlled to position the particle beam and/or the
patient to provide appropriate treatment to appropriate target
areas. In some example implementations, the various components can
be controlled to perform treatment with respect to any part of the
target, and are not constrained to treatment relative to a defined
isocenter.
[0115] In some implementations, the treatment site imaging
system(s) alone may be used to identify the location of the
irradiation target, with or without fiducials, and to track
movement of the target following repositioning or other event.
[0116] Referring to FIG. 8, a collision avoidance system 88 may be
controlled to identify the locations of various components of the
particle therapy system, the patient and other structures in the
treatment space, and to feed-back that information to the control
system. More specifically, as described, in some implementations,
the system is automated in that the beam spreader, the particle
accelerator and its components, and the treatment couch are
controlled to move, automatically, to different positions between
applications of the particle beam. This automatic movement is
advantageous in that it eliminates the need for a human to
reconfigure the system (e.g., the nozzle, accelerator, and/or couch
positions) between applications of particle beam. However,
automation will typically require coordination among the various
moving parts of the system, which may be implemented by the control
systems described here. For safety purposes, the collision
avoidance system 88 tracks motion of system components, such as the
treatment couch, the particle accelerator, the carriage containing
the energy degrader and collimator, and so forth, and relays
information about that motion to the control system. If the control
system detects, based on that information, that there is a
possibility of a collision between two components or between a
component and the patient or other structures/objects in the
treatment space, the control system intervenes and changes the
trajectory of one or more of the components or halts the motion of
one or more of the components.
[0117] In some implementations, the collision avoidance system 88
may be implemented using one or more sensors, a 3D imaging system,
laser positioning, sonar, ultrasound, or any appropriate
combination thereof. In some implementations, other types of device
detection systems may be used instead of, or in addition to, those
described herein to implement collision avoidance.
[0118] In addition to the foregoing, the nozzle--which in some
implementations is located on the inner gantry--may be retracted
away from the patient or other object in the treatment space in
order to avoid collisions. In some examples, this aspect of nozzle
operation may be controlled by the control system based on feedback
information from the collision avoidance system.
[0119] Referring to FIG. 14, control of the particle therapy system
components 141 may include, but is not limited to, operation of and
positioning and repositioning of the spreader--e.g., the one or
more scanning magnets or scattering foils, the outer and inner
gantries, the treatment couch, the nozzle, the beam shaping
elements--e.g., the energy degrader and collimator, the carriage on
which the beam shaping elements are mounted, the imaging systems
(including, but not limited to, systems for beam targeting), the
collision avoidance system, and the synchrocyclotron (both
translation positioning and orientation positioning). Such control
may implemented by a control system 140. Control system 140 may
include one or more computer systems as described herein and/or
other control electronics. For example, control of the particle
therapy system and its various components may be implemented using
hardware or a combination of hardware and software. For example, a
system like the ones described herein may include various
controllers and/or processing devices located at various points,
e.g., a controller or other type of processing device may be
embedded in each controllable device or system. A central computer
may coordinate operation among the various controllers or other
types of processing devices. The central computer, controllers,
and/or processing devices may execute various software routines to
effect control and coordination of testing, calibration, and
particle therapy treatment.
[0120] To automate treatment in the manner described, an example
TPS 142, which is in communication with the particle therapy
system, defines a treatment session by sets of positions of a
patient and positions of components of a particle (e.g., proton)
output device. In an example, each set of positions may include, at
least, a unique combination of a position of the treatment couch
and a position of the output device, where the position of the
output device is defined, at least in part, based on a position of
the outer gantry (e.g., [couch position, beam position]). For each
element in this set, a pattern of radiation is to be administered
to at least a portion of an irradiation target. The motion of the
patient is not limited to rotations, but also includes at least one
translation, enabling the system to improve treatment of linear
targets. The TPS may be implemented on one or more computer systems
of the type described herein and/or other control electronics, and
may be configured to communicate with control system 140 using any
appropriate wired or wireless media. In some implementations, this
allows a particle therapy system having a small beam field to treat
large irradiation targets effectively and efficiently.
[0121] As explained above, the particle therapy system may have a
relatively small beam field size, which is dictated, at least in
part, by the distance between the particle/proton output device
(for example, the spreader, the accelerator, or some other device
capable of beam delivery) and the patient. In some implementations,
the particle therapy system has a spreader-to-patient isocenter
distance in a range of 1 m to 2 m (e.g., 1.5 m or less than 2 m)
and a beam field area that is about 20 cm by 20 cm or less. In some
implementations, the particle therapy system has a source-to-axis
distance in a range of 1 m to 2 m (e.g., 1.5 m or less than 2 m)
and a beam field area that is about 30 cm by 30 cm or less. Other
values of the spreader-to-patient isocenter distance and beam field
area also may be implemented.
[0122] In example implementations described herein, the spots size
is dominated by a distance between the energy degrader, which
dominates the beamline's contribution to beam divergence, and the
patient. That is a distance that it may be advantageous to reduce,
and why it may be beneficial to reduce the size of the components
mounted to the nozzle. In some implementations, it is possible to
perform downstream treatment of a defined isocenter.
[0123] FIG. 15 shows an example of a beam field 150 relative to an
irradiation target 159, which may be a tumor in the patient. Thus,
in this example, the synchrocyclotron 151 does not have a beam
field that is large enough to treat the entire irradiation target.
Traditionally, particle beam 155 would be scanned across this first
beam field 150 for a first treatment and then a radiation therapist
would enter the treatment room and reposition the nozzle or other
output device and/or the patient to scan the particle beam 155
across the second beam field 152 at a next isocenter. This process
was repeated to treat the entire target, as described above.
[0124] The particle therapy system described herein, however, does
not require a therapist to reposition the patient or the nozzle
between treatments, at least in some cases (that is, the system
does not prohibit therapist intervention, if necessary). For
example, a computer system (e.g., control electronics) that
controls the particle therapy system receives a treatment plan for
the irradiation target. The treatment plan automates treatment
using different beam fields (e.g., 150, 152). In some examples, the
treatment plan also does not rely on isocenter locations for
patient or beam positioning, although in other examples, isocenters
may be used.
[0125] In some implementations, operation of the particle therapy
system may be controlled with a button located outside of the
proton center. For example, a single press of the button could
begin treatment and, in some examples, the treatment may continue
uninterrupted, and without requiring human intervention, across and
using multiple beam fields until an entire treatment area has been
treated. In some example implementations, the entire treatment of
an irradiation target may be delivered in less than about five
minutes which is enabled by the automated (e.g., without human
intervention) beam field sequencing described herein. In some
implementations, human intervention may be included in the
treatment process. For example, a human may press the button (or
buttons) located inside or outside of the proton center to begin
application of radiation, and thus a new treatment, each time
various components of the particle therapy system are automatically
positioned following a preceding treatment.
[0126] In operation, the computer system interprets and/or executes
instructions from the TPS to control one or more components of the
particle therapy system in order to position the patient (and thus
the target) and the particle beam at appropriate locations for
treatment. Examples of components of the particle therapy system
that may be controlled automatically to position the patient and
the particle beam to implement automated treatment may include, but
are not necessarily limited to one or more of the following: the
spreader and/or the synchrocyclotron (including translational or
pivotal movement), the outer gantry (for rotation of the
synchrocyclotron and/or the spreader alone or in combination), the
inner gantry (for positioning of the nozzle, including the beam
shaping elements), the nozzle, the scanning magnet(s) or the
scattering foil(s) (e.g., the beam spreader), the range modulator,
the configurable collimator, the carriage to which the components
of the nozzle are coupled, the treatment couch, the treatment site
imaging system(s), and the collision avoidance system.
[0127] In addition, components of the synchrocyclotron may support
treatment by controlling, e.g., by varying, the intensity of the
particle beam during treatment. Variations in intensity may be
achieved by controlling the number of particles per pulse of the
particle beam. For example, the RF voltage sweep may be altered, or
the operation of the ion source may be controlled, to select a
desired intensity of the particle beam. Examples of processes that
may be used by the synchrocyclotron described herein to control the
intensity of the output particle beam are described in U.S. Patent
Publication No. 2014/0094638 entitled "Controlling Intensity of a
Particle Beam", the contents of which are incorporated herein by
reference.
[0128] Using appropriate command and control protocols, in an
example, the computer system 140 that directs operation of the
particle therapy system controls operation, including positioning,
of one or more of the spreader and/or the synchrocyclotron
(including translational or pivotal movement), the outer gantry
(for rotation of the synchrocyclotron and/or the spreader alone or
in combination), the nozzle, the scanning magnet(s) or the
scattering foil(s) (e.g., the beam spreader), the range modulator,
the configurable collimator, and the carriage to which the
components of the nozzle are coupled to position the particle beam
at an appropriate location in the treatment space (e.g., the proton
center) to administer radiation dosage to a target. Using
appropriate command and control protocols, in an example, the
computer system that directs operation of the particle therapy
system controls operation of the treatment couch to position the
patient, and thus the irradiation target, at an appropriate
location in the treatment space to administer radiation dosage via
the particle beam. Using appropriate command and control protocols,
in an example, the computer system that directs operation of the
particle therapy system controls operation of the synchrocyclotron
to produce a particle beam having characteristics (e.g., intensity,
energy, etc.) that are appropriate to administer required doses of
radiation at locations defined in a treatment plan. Instructions in
the TPS state where and when radiation is to be applied, and define
the positions of the various system components needed to provide
the appropriate radiation. Using appropriate command and control
protocols, in an example, the computer system also directs
operation of the site imaging system and the collision avoidance
system to implement automated treatment.
[0129] Control over operation, including movement, of the spreader
and/or the synchrocyclotron (including translational or pivotal
movement), the outer gantry (for rotation of the synchrocyclotron
and/or the spreader alone or in combination), the nozzle, the
scanning magnet(s) or the scattering foil(s) (e.g., the beam
spreader), the range modulator, the configurable collimator, the
carriage to which the components of the nozzle are coupled, and the
treatment couch enables positioning the patient and the beam with
multiple degrees of freedom that exceed simple isocentric rotations
of the particle accelerator and the treatment couch or that exceed
simple isocentric rotations of the spreader and the treatment
couch. For example, in some implementations, rotation of the gantry
provides one degree of freedom; movement of, or produced by, the
scanning magnet(s) provides two degrees of freedom; movement of, or
produced by, the range modulator provides one degree of freedom;
and movement of the treatment couch provides six degrees of
freedom, resulting in ten degrees of freedom. In some
implementations, as described herein, the spreader and/or the
particle accelerator (and, thus, the particle beam) may be
translatable (e.g., movable in a linear motion) in one, two, and/or
three dimensions for additional degree(s) of freedom of movement.
As explained herein, in some implementations, the spreader and/or
the particle accelerator (and, thus, the particle beam) may be
pivotable or be mounted to a gimbal (e.g., a pivoted support that
allows the rotation of an object about a single axis), resulting in
one or more additional degree(s) of freedom of movement. Control
over movement of the carriage may provide an additional degree of
freedom.
[0130] As noted, the computer system controls operation, including
movement, of one or more of the spreader and/or the
synchrocyclotron (including translational or pivotal movement), the
outer gantry (for rotation of the synchrocyclotron and/or the
spreader alone or in combination), the nozzle, the scanning
magnet(s) or the scattering foil(s) (e.g., the beam spreader), the
range modulator, the configurable collimator, the carriage to which
the components of the nozzle are coupled, and the treatment couch
to position the particle beam and/or the patient for treatment, and
to automatically reposition the particle beam and/or the patient
for additional, successive treatments. When that the patient is
moved, the computer system may instruct, and control, the site
imaging system(s) automatically to capture an image of the patient
(and thus the irradiation target) at a new position, and to
determine the location of the irradiation target at the new
position. Movement may include pivoting, rotation and/or
translation. For example, changes in patient orientation may be
relevant to IMPT treatments. Determining the location of the
irradiation target at the new position may be implemented as
described above or using other appropriate methods. Thereafter,
treatment may proceed. During movement, the collision avoidance
system operates as described above to reduce the possibility of
collision among components of the system. The collision avoidance
system acts to reduce the possibility of collision among objects in
the treatment space that are part of, and not part of, the
system.
[0131] In some implementations, if it is determined, through
patient monitoring, that the patient has not moved between
treatment positions, then there may be no need to perform
re-imaging or other processes to locate the irradiation target
after each movement.
[0132] Movement of the patient couch may be in concert with
treatment that occurs across beam fields. For example, in some
implementations, the TPS may instruct automated treatment of a
first beam field, followed by treatment of a second beam field,
followed by treatment of a third beam field, and so forth. To
generalize further, in some implementations, the moving parts of
the system may be configured for each beam spot, making the beam
delivery effectively fieldless in that the delivery is not
constrained by field. Moreover, the particle therapy system may be
controlled to move the particle beam back-and-forth between the
same two beam fields multiple times, if necessary, independent of
any system isocenters, if defined. In this example, as described
elsewhere herein, movement of all components and control over
imaging and sensors is automated, allowing the entire treatment
process to be performed without a therapist manually repositioning
the patient or the spreader and/or the particle accelerator.
[0133] Referring to FIG. 16, different, adjacent beam fields 161,
162 may overlap at an area 166. The adjacent beam fields may be for
treatment of target 170. This overlap area may be subjected to
particle beams from different beam fields--in this example,
particle beam 164 for beam field 162 and particle beam 165 for beam
field 161. Because particle--and, in particular, proton--radiation
is cumulative, if no corrective action is taken, beam overlap can
cause too much radiation to be deposited in the areas of overlap.
Likewise, if the areas of overlap are avoided, or the beams are not
applied there correctly, then insufficient radiation for treatment
may be applied (e.g., a gap). Accordingly, the example particle
therapy system may be controlled to vary the intensity of the
particle beam in areas of overlap, thereby allowing for beam
overlap, while still ensuring that appropriate dosage is applied to
areas of overlap between adjacent beam fields.
[0134] More specifically, in some implementations, the TPS may
provide instructions in the treatment plan specifying the intensity
of the beam at areas of overlap between adjacent beam fields. For
example in an overlap area, particle beams from different beam
fields may have lower intensities (e.g., a lesser concentration of
protons) than particle beams in the beam fields, but outside the
overlap area. The intensities of the beam may decrease further from
the center of the beam field in a feathering effect. In this
example, beam intensities are controlled so that the beams produce,
in an overlap area, such as area 166, a uniform distribution of
particles across the different beam fields. In some
implementations, this uniform distribution is the same as the
distribution in non-overlapping areas of one or both of the beam
fields; however, because the distribution may vary even within a
single beam field, this need not be the case. Specifically, the
control system is configured to provide automated control of the
particle accelerator to control intensities of the particle beams
for the different beam fields so that cumulative intensities at
areas of overlap between two or more particle beams reach a target
beam intensity or are within a predefined range of the target
intensity, and do not deviate from (e.g., exceed or fall below) the
target intensity by more than a predefined amount.
[0135] In some examples, a certain amount of overlap, as shown in
FIG. 16, is contemplated and accounted for by appropriate control
over the particle beam, including variations in beam intensities at
or near areas of overlap between adjacent beam fields. In the
example of FIG. 16, intensity is represented by shading of the
lines representing beams 164 and 165. As shown, the lines are
darkest at non-overlapping areas, representing maximum (or
appropriate) intensity for that beam field. The lines become
progressively lighter as the lines move into the overlap area,
representing a decrease in intensity of (e.g., concentration of
particles in) the respective particle beams. For example, in the
case of particle beam 165, as the particle beam is moved during
scanning in the direction of arrow 167, the intensity of particle
beam 165 decreases when it enters the overlap area 166 and
continues to decrease to a minimum value at the end of the overlap
area 166 furthest into beam field 162. Likewise, in the case of
particle beam 164, as the particle beam is moved during scanning in
the direction of arrow 168, the intensity of particle beam 164
decreases when it enters the overlap area 166 and continues to
decrease to a minimum value at the end of the overlap area 166
furthest into beam field 161. In both cases, the intensities of the
particle beams are controlled in the overlap areas such that the
cumulative result from both beams in the overlap area is a uniform
distribution of particles (or whatever other distribution is
desired).
[0136] Thus, the overlap areas need not be avoided; appropriate
doses of radiation are applied in the overlap areas; and the
overlap areas between beam fields need not act as an impediment to
automated operation of the treatment process. The configurable
collimator described above may also be employed, where appropriate,
to shape the beam at areas of overlap between adjacent beam fields
or elsewhere. It is noted that the variations in intensity in the
overlap areas are, effectively, a mitigation resulting from the
risk of beam positioning errors/uncertainties. If automated
positioning of the particle beam is precisely controlled at all
locations of the irradiation target, dose distributions may not
need to be controlled in the manner described with respect to FIG.
16.
[0137] As noted, the combination of movement of the treatment couch
and/or the particle beam may produce a relative rotational
movement, a relative pivotal movement, and/or a relative
translational movement. Rotational movements may be used, e.g., in
IMPT treatments, whereas translational movements may be used, e.g.,
to treat across beam fields. Rotational movements and translational
movements, or combinations thereof, are not limited to these
contexts, and may have applicability outside of IMPT and treatment
across beam fields. In some implementations, the system may
implement an effective translational movement of 5 cm or more,
e.g., 5 cm to 50 cm or more, thereby enabling treatment of
relatively long areas, such as a human spine, which could
potentially span multiple beam fields.
[0138] The example particle therapy system may be controlled to
implement any number of combined patient and beam positions that
are appropriate for a given treatment plan. A combined patient and
beam position may include any unique combination of a single
position of the treatment couch (or patient) and a single position
of the beam. By way of example, in a single treatment session, the
example particle therapy system may be controlled to implement any
appropriate number of combined patient and beam positions. Examples
include, but are not limited to, two or more combined patient and
beam positions, five or more combined patient and beam positions,
ten or more combined patient and beam positions, 100 or more
combined patient and beam positions, and 10,000 or more combined
patient and beam positions. To reiterate, each combined patient and
beam position is achieved through computer (e.g., automated)
control over components of the particle therapy system (treatment
couch, gantry, scanning components, etc.) and computer control over
imaging system(s), such as the site imaging system(s) and the
collision avoidance system. A TPS may provide appropriate
instructions to effect control. In some implementations, the TPS
may know beforehand the capabilities of the particle therapy
system, and determine instructions for the treatment plan
automatically based on a radiation dosage recommended by a medical
professional and knowledge of the location, shape, and other
relevant characteristics of the irradiation target (e.g., a tumor).
Rather than limiting the number of beam fields, due to the various
components described herein that enable beam positioning, in some
examples, the particle therapy system described herein enables
precise control over particle beam positioning, thereby effectively
increasing the number of beam fields (e.g., to one for each
position of the beam and patient) in order to increase the accuracy
at which particle therapy is delivered.
[0139] The time for a treatment session will vary based on any
number of factors including, but not limited to, the size of the
target, the dosage to be applied, the number of combined patient
and beam positions to be implemented, and so forth. In some cases,
an average treatment time may be less than 15 minutes or less than
45 minutes in some examples.
[0140] Operation of the example particle therapy systems described
herein, and operation of all or some component thereof, can be
controlled (as appropriate), at least in part, using one or more
computer program products, e.g., one or more computer programs
tangibly embodied in one or more non-transitory machine-readable
media, for execution by, or to control the operation of, one or
more data processing apparatus, e.g., a programmable processor, a
computer, multiple computers, and/or programmable logic
components.
[0141] A computer program can be written in any form of programming
language, including compiled or interpreted languages, and it can
be deployed in any form, including as a stand-alone program or as a
module, component, subroutine, or other unit suitable for use in a
computing environment. A computer program can be deployed to be
executed on one computer or on multiple computers at one site or
distributed across multiple sites and interconnected by a
network.
[0142] Actions associated with implementing all or part of the
operations of the example particle therapy systems described herein
can be performed by one or more programmable processors executing
one or more computer programs to perform the functions described
herein. All or part of the operations can be implemented using
special purpose logic circuitry, e.g., an FPGA (field programmable
gate array) and/or an ASIC (application-specific integrated
circuit).
[0143] Processors suitable for the execution of a computer program
include, by way of example, both general and special purpose
microprocessors, and any one or more processors of any kind of
digital computer. Generally, a processor will receive instructions
and data from a read-only storage area or a random access storage
area or both. Elements of a computer (including a server) include
one or more processors for executing instructions and one or more
storage area devices for storing instructions and data. Generally,
a computer will also include, or be operatively coupled to receive
data from, or transfer data to, or both, one or more
machine-readable storage media, such as mass PCBs for storing data,
e.g., magnetic, magneto-optical disks, or optical disks.
Non-transitory machine-readable storage media suitable for
embodying computer program instructions and data include all forms
of non-volatile storage area, including by way of example,
semiconductor storage area devices, e.g., EPROM, EEPROM, and flash
storage area devices; magnetic disks, e.g., internal hard disks or
removable disks; magneto-optical disks; and CD-ROM and DVD-ROM
disks.
[0144] Any "electrical connection" as used herein may imply a
direct physical connection or a wired or wireless connection that
includes intervening components but that nevertheless allows
electrical signals to flow between connected components. Any
"connection" involving electrical circuitry that allows signals to
flow, unless stated otherwise, is an electrical connection and not
necessarily a direct physical connection regardless of whether the
word "electrical" is used to modify "connection".
[0145] Any two more of the foregoing implementations may be used in
an appropriate combination with an appropriate particle accelerator
(e.g., a synchrocyclotron). Likewise, individual features of any
two more of the foregoing implementations may be used in an
appropriate combination.
[0146] Elements of different implementations described herein may
be combined to form other implementations not specifically set
forth above. Elements may be left out of the processes, systems,
apparatus, etc., described herein without adversely affecting their
operation. Various separate elements may be combined into one or
more individual elements to perform the functions described
herein.
[0147] In some implementations, the synchrocyclotron used in the
particle therapy system described herein may be a variable-energy
synchrocyclotron. In some implementations, a variable-energy
synchrocyclotron is configured to vary the energy of the output
particle beam by varying the magnetic field in which the particle
beam is accelerated. For example, the current may be set to any one
of multiple values to produce a corresponding magnetic field. In an
example implementation, one or more sets of superconducting coils
receives variable electrical current to produce a variable magnetic
field in the cavity. In some examples, one set of coils receives a
fixed electrical current, while one or more other sets of coils
receives a variable current so that the total current received by
the coil sets varies. In some implementations, all sets of coils
are superconducting. In some implementations, some sets of coils,
such as the set for the fixed electrical current, are
superconducting, while other sets of coils, such as the one or more
sets for the variable current, are non-superconducting (e.g.,
copper) coils.
[0148] Generally, in a variable-energy synchrocyclotron, the
magnitude of the magnetic field is scalable with the magnitude of
the electrical current. Adjusting the total electric current of the
coils in a predetermined range can generate a magnetic field that
varies in a corresponding, predetermined range. In some examples, a
continuous adjustment of the electrical current can lead to a
continuous variation of the magnetic field and a continuous
variation of the output beam energy. Alternatively, when the
electrical current applied to the coils is adjusted in a
non-continuous, step-wise manner, the magnetic field and the output
beam energy also varies accordingly in a non-continuous (step-wise)
manner. The scaling of the magnetic field to the current can allow
the variation of the beam energy to be carried out relatively
precisely, thus reducing the need for an energy degrader. An
example of a variable-energy synchrocyclotron that may be used in
the particle therapy system is described in U.S. Patent Publication
No. 2014/0371511 entitled "Particle Accelerator That Produces
Charged Particles Having Variable Energies", the contents of which
are incorporated herein by reference. Implementations that employ a
variable-energy synchrocyclotron
[0149] In some implementations, a particle accelerator other than a
synchrocyclotron may be used in the particle therapy system
described herein. For example, a cyclotron, a synchrotron, a linear
accelerator, or the like may be substituted for the
synchrocyclotron described herein. Although a rotational gantry has
been described (e.g., the outer gantry), the example particle
therapy systems described herein are not limited to use with
rotational gantries. Rather, a particle accelerator may be mounted,
as appropriate, on any type of robotic or other controllable
mechanism(s)--characterized herein also as types of gantries--to
implement movement of the particle accelerator. For example, the
particle accelerator and/or the spreader may be mounted on or more
robotic arms to implement rotational, pivotal, and/or translational
movement of the accelerator and/or the spreader relative to the
patient. In some implementations, the particle accelerator and/or
the spreader may be mounted on a track, and movement along the
track may be computer-controlled. In this configuration, rotational
and/or translational and/or pivotal movement of the accelerator
and/or the spreader relative to the patient can also be achieved
through appropriate computer control.
[0150] In some implementations, the particle accelerator itself may
not move relative to the patient, as described herein. For example,
in some implementations, the particle accelerator may be a
stationary machine or at least not mounted for movement relative
the patient. In examples like this, the particle accelerator may
output its particle beam from the extraction channel to a
transmission channel. The transmission channel may include magnets
and the like for controlling magnetic fields contained therein in
order to transport the particle beam to one or more remote
locations, such as one or more treatment rooms. In each treatment
room, the transmission channel may direct the beam to a beam
spreader or other apparatus that is mounted for movement as
described herein (e.g., to an outer gantry or other device). The
beam spreader may thus be in place of the accelerator described
elsewhere herein. However, in some examples, except for positioning
of the accelerator, the spreader, and the transmission channel, the
configuration and operation of this implementation of the particle
accelerator system is the same as the configuration and operation
of other implementations of the particle therapy system described
elsewhere herein, as appropriate.
[0151] For example, using appropriate command and control
protocols, in an example, the computer system 140 that directs
operation of the particle therapy system controls operation,
including positioning, of one or more of the gantry-mounted
spreader (including translational, pivotal movement, and/or
rotational movement), the beam shaping elements, the range
modulator, the configurable collimator, the carriage to which the
beam shaping elements are coupled, a nozzle, and the treatment
couch to position the particle beam at an appropriate location in
the treatment space to administer radiation dosage to a target.
Using appropriate command and control protocols, in an example, the
computer system that directs operation of the particle therapy
system controls operation of the treatment couch to position the
patient, and thus the irradiation target, at an appropriate
location in the treatment space to administer radiation dosage via
the particle beam. Using appropriate command and control protocols,
in an example, the computer system that directs operation of the
particle therapy system also controls operation of the
synchrocyclotron to produce a particle beam having characteristics
(e.g., intensity, energy, etc.) that are appropriate to administer
required doses of radiation at locations defined in a treatment
plan. Instructions in the TPS state where and when radiation is to
be applied, and define the positions of the various system
components needed to provide the appropriate radiation. Other
possible operations of the particle therapy system are as described
elsewhere herein.
[0152] Another example implementation of a particle therapy system
in which the control systems described herein may be implemented is
described in U.S. Pat. No. 7,728,311 entitled "Charged Particle
Radiation Therapy", the contents of which are incorporated herein
by reference. The content incorporated by reference includes, but
is not limited to, the description of the synchrocyclotron and the
gantry system holding the synchrocyclotron found in U.S. Pat. No.
7,728,311.
[0153] Other implementations not specifically described herein are
also within the scope of the following claims.
* * * * *