U.S. patent application number 12/198645 was filed with the patent office on 2010-03-04 for patient setup error evaluation and error minimizing setup correction in association with radiotherapy treatment.
Invention is credited to Supratik Bose, Himanshu P. Shukla.
Application Number | 20100054409 12/198645 |
Document ID | / |
Family ID | 41416218 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100054409 |
Kind Code |
A1 |
Bose; Supratik ; et
al. |
March 4, 2010 |
PATIENT SETUP ERROR EVALUATION AND ERROR MINIMIZING SETUP
CORRECTION IN ASSOCIATION WITH RADIOTHERAPY TREATMENT
Abstract
In some embodiments, a method includes receiving, in a
processor, information indicative of (i) a treatment plan defining
planned treatment beams, (ii) a patient volume relative to a
reference, (iii) ideal intersections of the planned treatment beams
with the patient volume at the time the patient is to be treated,
(iv) any constraints that prevent achievement of the recommended
repositioning using only the patient support, (v) an allowable
change to a gantry position from a planned value and an allowable
change to a collimator position from a planned value; defining, in
the processor, a plurality of alternatives based at least in part
on the information indicative of any constraints of the patient
support and the information indicative of allowable movement of the
gantry and collimator, each alternative defining a modified patient
support position and modified beams, each modified beam being based
at least in part on a respective one of the planned treatment
beams, the change to the position of the gantry for the respective
planned treatment beam and the change to the position of the
collimator for the respective planned treatment beam; determining,
in the processor, for each modified beam of each alternative, an
intersection of the patient volume and the modified beam, with the
patient volume positioned on the patient support and the patient
support having the modified patient support position defined by the
alternative; and defining, in the processor, for each alternative,
a measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative.
Inventors: |
Bose; Supratik; (Walnut
Creek, CA) ; Shukla; Himanshu P.; (Lafayette,
CA) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
41416218 |
Appl. No.: |
12/198645 |
Filed: |
August 26, 2008 |
Current U.S.
Class: |
378/65 |
Current CPC
Class: |
A61N 5/1049 20130101;
A61N 5/103 20130101; G16H 20/30 20180101 |
Class at
Publication: |
378/65 |
International
Class: |
A61N 5/10 20060101
A61N005/10 |
Claims
1. A method comprising: receiving, in a processor, information
indicative of (i) a treatment plan defining planned treatment
beams, (ii) a patient volume relative to a reference, (iii) ideal
intersections of the planned treatment beams with the patient
volume at the time the patient is to be treated, (iv) any
constraints that prevent achievement of the recommended
repositioning using only the patient support, (v) an allowable
change to a gantry position from a planned value and an allowable
change to a collimator position from a planned value; defining, in
the processor, a plurality of alternatives based at least in part
on the information indicative of any constraints of the patient
support and the information indicative of allowable movement of the
gantry and collimator, each alternative defining a modified patient
support position and modified beams, each modified beam being based
at least in part on a respective one of the planned treatment
beams, the change to the position of the gantry for the respective
planned treatment beam and the change to the position of the
collimator for the respective planned treatment beam; determining,
in the processor, for each modified beam of each alternative, an
intersection of the patient volume and the modified beam, with the
patient volume positioned on the patient support and the patient
support having the modified patient support position defined by the
alternative; and defining, in the processor, for each alternative,
a measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative.
2. The method of claim 1 wherein the modified patient support
position defined by each alternative is the same.
3. The method of claim 1 wherein the amount of change to the gantry
position defined by each alternative is the same.
4. The method of claim 1 wherein the amount of change to the
collimator position defined by each alternative is the same.
5. The method of claim 1 wherein for each alternative, defining the
measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative comprises:
defining, for each modified beam of the alternative, a measure of
difference between the intersection and a respective one of the
ideal intersections; and defining the measure of difference between
the ideal intersections and the intersections for the modified
beams based at least in part on the measure of difference between
the intersection and the respective one of the ideal intersections
for each modified beam of the alternative.
6. The method of claim 5 wherein the measure of difference between
each intersection and the respective ideal intersection is based at
least in part on a distance between a point defined by the
intersection and a corresponding point defined by the respective
ideal intersection.
7. The method of claim 6 wherein each intersection for a modified
beam defines a pyramid having a tip and a polygonal base, the tip
defined by a source for the modified beam, the polygonal base
having a plurality of corners, and wherein a measure of difference
between each intersection and the respective ideal intersection is
determined using a method comprising: defining a distance between
the tip of the intersection and a tip of the respective ideal
intersection; defining a square of the distance between the tips;
defining for each corner of the polygonal base of the intersection,
a distance between the corner and a corresponding corner of the
respective ideal intersection; defining a square of the distance
for each corner; and defining the measure of difference based at
least in part on a sum of the square of the distance between the
tips and the square of the distance defined for each corner of the
polygon.
8. The method of claim 1 wherein for each alternative, defining the
measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative comprises:
defining, for each modified beam of the alternative, a measure of
difference between the intersection and a respective one of the
ideal intersections; defining, for each modified beam of the
alternative, a weighted difference defined as a product of a weight
and the measure of difference between the intersection and a
respective one of the ideal intersections, wherein the weight is
based at least in part on a dosimetric strength of the modified
beam relative to respective dosimetric strengths of the other
modified beams of the alternative; and defining the measure of
difference between the ideal intersections and the intersections
for the modified beams based at least in part on the weighted
difference for each modified beam of the alternative.
9. The method of claim 8 wherein the measure of difference between
the ideal intersections and the intersections for the modified
beams is based at least in part on the sum of the weighted
difference for each modified beam of the alternative.
10. The method of claim 1 further comprising selecting one
alternative of the plurality of alternatives based at least in part
on the measure of difference for the one alternative.
11. The method of claim 1 further comprising: selecting one
alternative of the plurality of alternatives for which the measure
of difference between the ideal intersections and the intersections
for the modified beams of the alternative is no greater than the
measure of difference between the ideal intersections and the
intersections for the modified beams of the other alternatives.
12. Apparatus comprising: a processor to: receive information
indicative of (i) a treatment plan defining planned treatment
beams, (ii) a patient volume relative to a reference, (iii) ideal
intersections of the planned treatment beams with the patient
volume at the time the patient is to be treated, (iv) any
constraints that prevent achievement of the recommended
repositioning using only the patient support, (v) an allowable
change to a gantry position from a planned value and an allowable
change to a collimator position from a planned value; define a
plurality of alternatives based at least in part on the information
indicative of any constraints of the patient support and the
information indicative of allowable movement of the gantry and
collimator, each alternative defining a modified patient support
position and modified beams, each modified beam being based at
least in part on a respective one of the planned treatment beams,
the change to the position of the gantry for the respective planned
treatment beam and the change to the position of the collimator for
the respective planned treatment beam; determine for each modified
beam of each alternative, an intersection of the patient volume and
the modified beam, with the patient volume positioned on the
patient support and the patient support having the modified patient
support position defined by the alternative; and define for each
alternative, a measure of difference between the ideal
intersections and the intersections for the modified beams of the
alternative.
13. The apparatus of claim 12 wherein the modified patient support
position defined by each alternative is the same.
14. The apparatus of claim 12 wherein the amount of change to the
gantry position defined by each alternative is the same.
15. The apparatus of claim 12 wherein the amount of change to the
collimator position defined by each alternative is the same.
16. The apparatus of claim 12 wherein the processor comprises a
processor to: define, for each modified beam of the alternative, a
measure of difference between the intersection and a respective one
of the ideal intersections; and define the measure of difference
between the ideal intersections and the intersections for the
modified beams based at least in part on the measure of difference
between the intersection and the respective one of the ideal
intersections for each modified beam of the alternative.
17. The apparatus of claim 16 wherein the measure of difference
between each intersection and the respective ideal intersection is
based at least in part on a distance between a point defined by the
intersection and a corresponding point defined by the respective
ideal intersection.
18. The apparatus of claim 17 wherein each intersection for a
modified beam defines a pyramid having a tip and a polygonal base,
the tip defined by a source for the modified beam, the polygonal
base having a plurality of corners, and wherein the processor
comprises a processor to: define a distance between the tip of the
intersection and a tip of the respective ideal intersection; define
a square of the distance between the tips; define for each corner
of the polygonal base of the intersection, a distance between the
corner and a corresponding corner of the respective ideal
intersection; define a square of the distance for each corner; and
define the measure of difference based at least in part on a sum of
the square of the distance between the tips and the square of the
distance defined for each corner of the polygon.
19. The apparatus of claim 12 wherein the processor comprises a
processor to: define, for each modified beam of the alternative, a
measure of difference between the intersection and a respective one
of the ideal intersections; define, for each modified beam of the
alternative, a weighted difference defined as a product of a weight
and the measure of difference between the intersection and a
respective one of the ideal intersections, wherein the weight is
based at least in part on a dosimetric strength of the modified
beam relative to respective dosimetric strengths of the other
modified beams of the alternative; and define the measure of
difference between the ideal intersections and the intersections
for the modified beams based at least in part on the weighted
difference for each modified beam of the alternative.
20. The apparatus of claim 19 wherein the measure of difference
between the ideal intersections and the intersections for the
modified beams is based at least in part on the sum of the weighted
difference for each modified beam of the alternative.
21. The apparatus of claim 12 wherein the processor comprises a
processor to select one alternative of the plurality of
alternatives based at least in part on the measure of difference
for the one alternative.
22. The apparatus of claim 12 wherein the processor comprises a
processor to select one alternative of the plurality of
alternatives for which the measure of difference between the ideal
intersections and the intersections for the modified beams of the
alternative is no greater than the measure of difference between
the ideal intersections and the intersections for the modified
beams of the other alternatives.
23. An article comprising: a processor readable storage medium
having stored thereon instructions that if executed by a processor,
result in the following: receiving information indicative of (i) a
treatment plan defining planned treatment beams, (ii) a patient
volume relative to a reference, (iii) ideal intersections of the
planned treatment beams with the patient volume at the time the
patient is to be treated, (iv) any constraints that prevent
achievement of the recommended repositioning using only the patient
support, (v) an allowable change to a gantry position from a
planned value and an allowable change to a collimator position from
a planned value; defining a plurality of alternatives based at
least in part on the information indicative of any constraints of
the patient support and the information indicative of allowable
movement of the gantry and collimator, each alternative defining a
modified patient support position and modified beams, each modified
beam being based at least in part on a respective one of the
planned treatment beams, the change to the position of the gantry
for the respective planned treatment beam and the change to the
position of the collimator for the respective planned treatment
beam; determining for each modified beam of each alternative, an
intersection of the patient volume and the modified beam, with the
patient volume positioned on the patient support and the patient
support having the modified patient support position defined by the
alternative; and defining for each alternative, a measure of
difference between the ideal intersections and the intersections
for the modified beams of the alternative.
24. The article of claim 23 wherein the modified patient support
position defined by each alternative is the same.
25. The article of claim 23 wherein the amount of change to the
gantry position defined by each alternative is the same.
26. The article of claim 23 wherein the amount of change to the
collimator position defined by each alternative is the same.
27. The article of claim 23 wherein for each alternative, defining
the measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative comprises:
defining, for each modified beam of the alternative, a measure of
difference between the intersection and a respective one of the
ideal intersections; and defining the measure of difference between
the ideal intersections and the intersections for the modified
beams based at least in part on the measure of difference between
the intersection and the respective one of the ideal intersections
for each modified beam of the alternative.
28. The article of claim 25 wherein the measure of difference
between each intersection and the respective ideal intersection is
based at least in part on a distance between a point defined by the
intersection and a corresponding point defined by the respective
ideal intersection.
29. The article of claim 26 wherein each intersection for a
modified beam defines a pyramid having a tip and a polygonal base,
the tip defined by a source for the modified beam, the polygonal
base having a plurality of corners, and wherein a measure of
difference between each intersection and the respective ideal
intersection is determined using a article comprising: defining a
distance between the tip of the intersection and a tip of the
respective ideal intersection; defining a square of the distance
between the tips; defining for each corner of the polygonal base of
the intersection, a distance between the corner and a corresponding
corner of the respective ideal intersection; defining a square of
the distance for each corner; and defining the measure of
difference based at least in part on a sum of the square of the
distance between the tips and the square of the distance defined
for each corner of the polygon.
30. The article of claim 23 wherein for each alternative, defining
the measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative comprises:
defining, for each modified beam of the alternative, a measure of
difference between the intersection and a respective one of the
ideal intersections; defining, for each modified beam of the
alternative, a weighted difference defined as a product of a weight
and the measure of difference between the intersection and a
respective one of the ideal intersections, wherein the weight is
based at least in part on a dosimetric strength of the modified
beam relative to respective dosimetric strengths of the other
modified beams of the alternative; and defining the measure of
difference between the ideal intersections and the intersections
for the modified beams based at least in part on the weighted
difference for each modified beam of the alternative.
31. The article of claim 28 wherein the measure of difference
between the ideal intersections and the intersections for the
modified beams is based at least in part on the sum of the weighted
difference for each modified beam of the alternative.
32. The article of claim 23 wherein the method further comprises
selecting one alternative of the plurality of alternatives based at
least in part on the measure of difference for the one
alternative.
33. The article of claim 23 wherein the method further comprises
selecting one alternative of the plurality of alternatives for
which the measure of difference between the ideal intersections and
the intersections for the modified beams of the alternative is no
greater than the measure of difference between the ideal
intersections and the intersections for the modified beams of the
other alternatives.
Description
BACKGROUND
[0001] 1. Field
[0002] Some embodiments described herein relate generally to
radiation treatment, and more particularly, to methods, apparatus
and computer readable mediums for use in accounting, at least in
part, for changes in a position of a tumor or other target volume
within a patient.
[0003] 2. Description
[0004] According to conventional radiation therapy, a beam of
radiation is directed toward a tumor located within a patient. The
radiation beam delivers a predetermined dose of therapeutic
radiation to the tumor according to an treatment plan. The
delivered radiation kills cells of the tumor by causing ionizations
within the cells.
[0005] Recent advances in fractionated external beam radiation
therapy, such as three-dimensional conformal and
intensity-modulated radiation therapy (IMRT), have increased the
ability to deliver radiation doses that conform tightly to a target
volume. This tight conformance results in steep dose gradients
inside the volume. For example, IMRT can create a dose gradient of
10% mm.sup.-1 inside a target volume.
[0006] A treatment plan is designed assuming that a target volume
will be in a particular position relative to a beam source during
treatment. If the target volume is not positioned exactly as
assumed by the treatment plan, the steep gradient may occur within
sensitive healthy tissue surrounding the volume causing destruction
of healthy tissue while sparing some malignant tissue. Thus, it is
increasingly important to precisely position the target volume with
respect to the beam source.
[0007] It is not unusual for the target volume to change position
within the patient (e.g., to translate along one or more axes
and/or rotate about one or more axes) after a treatment plan is
designed but prior to performing the treatment.
[0008] In order to know current location of the target volume with
respect to the external beams, three-dimensional imaging of the
patient is often provided immediately prior to treatment delivery
(i.e., when the patient is on the treatment table). Systems
attempting to provide such imaging include: (1) a "CT on rails"
system, requiring an additional diagnostic computed tomography
machine in the treatment room; (2) a kilovoltage cone beam CT
(kVCBCT) system, consisting of an additional kilovoltage X-ray
source and detector attached to a treatment gantry; (3) a
megavoltage cone beam CT (MVCBCT) system using the pre-existing
treatment machine and an EPID for imaging; (4) a MVCT system, using
the pre-existing treatment machine with an attached arc of
detectors; (5) a tomotherapy system, replacing the traditional
treatment machine with a CT ring and a MV beam source; and (6) a
pre-treatment magnetic resonance imaging (MRI) of the patient.
[0009] From pre-treatment imaging, a shift of the target volume
with respect to the external beams can be found and the patient
position is adjusted in order to position the tumor targets in the
intended planned position with respect to the external beams.
Typically, the shift of such target volumes can be modeled as rigid
body rotation around along three orthogonal axis and rigid body
translation along three orthogonal axis. Adjustments of the patient
position typically involve movement of a radiotherapy couch.
[0010] For example, if the treatment system uses a robotic couch
having six degrees of freedom (e.g., translation along three axes
and rotation about three axes), the patient may be placed on the
robotic couch and the couch may be actuated so as to move the
patient to a position at which the tumor has a position, relative
to the treatment system, that is the same as that used in defining
the radiation treatment plan.
[0011] If the treatment system uses a table having only four
degrees of freedom (e.g., translation along three axes and rotation
about one axis), the positions of the table, the gantry and the
collimator may be each adjusted for each planned beam, such that
the tumor, the gantry and the collimator have the same relative
positioning as defined by the treatment plan. (See Yue et al., A
method to implement full six-degree target shift corrections for
rigid body in image-guided radiotherapy. Medical Physics,
33(1):21-31, January 2006.)
[0012] Alternately, without moving a treatment couch, the
collimator may be rotated and leaves and jaws of the collimator for
a beam may be repositioned to match a current position and shape of
the target volume with respect to the beam and the dose is then
recomputed. (See Ludlum et al., An algorithm for shifting MLC
shapes to adjust for daily prostate movement during concurrent
treatment with pelvic lymph nodes, Med Phys. December
2007;34(12):4750-6. See also Erik-Jan Rijkhorst et al. Strategy for
online correction of rotational organ motion for
intensity-modulated radiotherapy of prostate cancer. International
Journal of Radiation Oncology*Biology*Physics, 69:1608-1617,
2007).
SUMMARY
[0013] A disadvantage of the above method described in Yue et al.
for systems that use a table having only four degrees of freedom is
that the table position must be changed for each beam. This can
have the effect of increasing the time needed to perform the
treatment. Moreover, in some embodiments, any change to the
position of the treatment table has the potential to disturb the
position of the patient relative to the table.
[0014] A disadvantage of the above method described in Ludlum et
al. is that the dose must be recomputed, which can be time
consuming.
[0015] Some embodiments described herein provide a method, an
apparatus, and/or an article for use in association with radiation
treatment, and more particularly, for use in accounting, at least
in part, for changes in a position of a tumor or other target
volume within a patient.
[0016] Some embodiments described herein overcome one or more of
the disadvantages described above.
[0017] In one aspect, a method includes: receiving, in a processor,
information indicative of (i) a treatment plan defining planned
treatment beams, (ii) a patient volume relative to a reference,
(iii) ideal intersections of the planned treatment beams with the
patient volume at the time the patient is to be treated, (iv) any
constraints that prevent achievement of the recommended
repositioning using only the patient support, (v) an allowable
change to a gantry position from a planned value and an allowable
change to a collimator position from a planned value; defining, in
the processor, a plurality of alternatives based at least in part
on the information indicative of any constraints of the patient
support and the information indicative of allowable movement of the
gantry and collimator, each alternative defining a modified patient
support position and modified beams, each modified beam being based
at least in part on a respective one of the planned treatment
beams, a change to the position of the gantry for the respective
planned treatment beam and a change to the position of the
collimator for the respective planned treatment beam; determining,
in the processor, for each modified beam of each alternative, an
intersection of the patient volume and the modified beam, with the
patient volume positioned on the patient support and the patient
support having the modified patient support position defined by the
alternative; and defining, in the processor, for each alternative,
a measure of difference between the ideal intersections and the
intersections for the modified beams of the alternative.
[0018] In one aspect, an apparatus includes a processor to: receive
information indicative of (i) a treatment plan defining planned
treatment beams, (ii) a patient volume relative to a reference,
(iii) ideal intersections of the planned treatment beams with the
patient volume at the time the patient is to be treated, (iv) any
constraints that prevent achievement of the recommended
repositioning using only the patient support, (v) an allowable
change to a gantry position from a planned value and an allowable
change to a collimator position from a planned value; define a
plurality of alternatives based at least in part on the information
indicative of any constraints of the patient support and the
information indicative of allowable movement of the gantry and
collimator, each alternative defining a modified patient support
position and modified beams, each modified beam being based at
least in part on a respective one of the planned treatment beams, a
change to the position of the gantry for the respective planned
treatment beam and a change to the position of the collimator for
the respective planned treatment beam; determine for each modified
beam of each alternative, an intersection of the patient volume and
the modified beam, with the patient volume positioned on the
patient support and the patient support having the modified patient
support position defined by the alternative; and define for each
alternative, a measure of difference between the ideal
intersections and the intersections for the modified beams of the
alternative.
[0019] In one aspect, an article includes: a processor readable
storage medium having stored thereon instructions that if executed
by a processor, result in the following: receiving information
indicative of (i) a treatment plan defining planned treatment
beams, (ii) a patient volume relative to a reference, (iii) ideal
intersections of the planned treatment beams with the patient
volume at the time the patient is to be treated, (iv) any
constraints that prevent achievement of the recommended
repositioning using only the patient support, (v) an allowable
change to a gantry position from a planned value and an allowable
change to a collimator position from a planned value; defining a
plurality of alternatives based at least in part on the information
indicative of any constraints of the patient support and the
information indicative of allowable movement of the gantry and
collimator, each alternative defining a modified patient support
position and modified beams, each modified beam being based at
least in part on a respective one of the planned treatment beams, a
change to the position of the gantry for the respective planned
treatment beam and a change to the position of the collimator for
the respective planned treatment beam; determining for each
modified beam of each alternative, an intersection of the patient
volume and the modified beam, with the patient volume positioned on
the patient support and the patient support having the modified
patient support position defined by the alternative; and defining
for each alternative, a measure of difference between the ideal
intersections and the intersections for the modified beams of the
alternative.
[0020] In some embodiments, each alternative comprises a potential
setup correction that involves a one-time movement (translation
and/or vertical rotation) of the patient support and
planned-beam-specific modification of gantry and collimator
angle.
[0021] Some embodiments select an alternative having a minimum
difference with respect to the ideal intersections to compensate,
at least in part, for a six-degree of movement of the tumor or
other target volume within the patient.
[0022] In some embodiments, each treatment segment of each
radiotherapy beam emanates from a beam limiting device and produces
a pyramidal shaped intersection with the patient volume. In some
embodiments, the pyramidal shape has a polygonal shaped base at an
isocentric plane.
[0023] In some embodiments, a measure of geometric error is used to
compute the difference between each possible set-up correction and
the ideal setup correction.
[0024] In some embodiments, the measure of geometric error is based
on the Euclidean distance between corresponding points of the
pyramidal intersections generated by the proposed and ideal
pyramidal intersections. In some embodiments, the measure of
geometric error is based on the Euclidean distance between tips of
the pyramidal intersections generated by the proposed and ideal
pyramidal intersections and on the Euclidean distance between
corresponding corner points of the polygonal shaped base of the
pyramidal intersections generated by the proposed and ideal
pyramidal intersections.
[0025] In some embodiments, the geometric error for a treatment
segment may be weighted by the intended dose to be delivered by the
segment.
[0026] In some embodiments, an alternative that produces the least
dose-weighted geometric error, is obtained using an optimization
procedure.
[0027] In some embodiments, the modified patient support position
defined by each alternative is the same.
[0028] In some embodiments, the amount of change to the gantry
position defined by each alternative is the same.
[0029] In some embodiments, the amount of change to the collimator
position defined by each alternative is the same.
[0030] Some embodiments, define, for each modified beam of the
alternative, a measure of difference between the intersection and a
respective one of the ideal intersections, and define the measure
of difference between the ideal intersections and the intersections
for the modified beams based at least in part on the measure of
difference between the intersection and the respective one of the
ideal intersections for each modified beam of the alternative.
[0031] In some embodiments, the measure of difference between each
intersection and the respective ideal intersection is based at
least in part on a distance between a point defined by the
intersection and a corresponding point defined by the respective
ideal intersection.
[0032] In some embodiments, each intersection for a modified beam
defines a pyramid having a tip and a polygonal base, the tip
defined by a source for the modified beam, the polygonal base
having a plurality of corners.
[0033] Some embodiments define a distance between the tip of the
intersection and a tip of the respective ideal intersection;
further define a square of the distance between the tips; further
define for each corner of the polygonal base of the intersection, a
distance between the corner and a corresponding corner of the
respective ideal intersection; further define a square of the
distance for each corner; and further define the measure of
difference based at least in part on a sum of the square of the
distance between the tips and the square of the distance defined
for each corner of the polygon.
[0034] Some embodiments define, for each modified beam of the
alternative, a measure of difference between the intersection and a
respective one of the ideal intersections; further define, for each
modified beam of the alternative, a weighted difference defined as
a product of a weight and the measure of difference between the
intersection and a respective one of the ideal intersections,
wherein the weight is based at least in part on a dosimetric
strength of the modified beam relative to respective dosimetric
strengths of the other modified beams of the alternative; and
further define the measure of difference between the ideal
intersections and the intersections for the modified beams based at
least in part on the weighted difference for each modified beam of
the alternative.
[0035] In some embodiments, the measure of difference between the
ideal intersections and the intersections for the modified beams is
based at least in part on the sum of the weighted difference for
each modified beam of the alternative.
[0036] Some embodiments select one alternative of the plurality of
alternatives based at least in part on the measure of difference
for the one alternative.
[0037] Some embodiments select one alternative of the plurality of
alternatives for which the measure of difference between the ideal
intersections and the intersections for the modified beams of the
alternative is no greater than the measure of difference between
the ideal intersections and the intersections for the modified
beams of the other alternatives.
[0038] One or more of the alternatives may avoid change to the
position of the patient support. This may help reduce the potential
to disturb the position of the patient relative to the patient
support.
[0039] Although various features, attributes and/or advantages may
be described and/or may be apparent in light of the description, it
should be understood that unless stated otherwise, such features,
attributes and/or advantages are not required and need not be
present in all aspects and/or embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Various embodiments will be apparent from the following
detailed description and accompanying drawings, in which like
reference numerals designate like parts, and wherein:
[0041] FIG. 1 is a perspective view of a radiation treatment room
according to some embodiments;
[0042] FIG. 2 is a perspective view of a portion of the radiation
treatment room according to some embodiments;
[0043] FIG. 3 is a perspective view of a radiation treatment room
according to some embodiments;
[0044] FIG. 4 is a perspective view of portion of a radiation
treatment room and a patient volume according to some
embodiments;
[0045] FIG. 5 is a block diagram of an internal architecture of
radiation treatment devices according to some embodiments;
[0046] FIG. 6 is a flow diagram of a process according to some
embodiments;
[0047] FIG. 7 is a flow diagram of a process according to some
embodiments;
[0048] FIG. 8 is a flow diagram of a process according to some
embodiments;
[0049] FIG. 9 is a flow diagram of a process according to some
embodiments;
[0050] FIG. 10 is a diagrammatic representation of an ideal
intersection and a modified intersection, according to some
embodiments;
[0051] FIG. 11 is a table of a subset of alternatives within a
search space, in accordance with some embodiments, is described
below with respect to FIG. 11; and
[0052] FIGS. 12A-12D are a flow diagram of a process according to
some embodiments.
DETAILED DESCRIPTION
[0053] FIG. 1 is a perspective view of a radiation treatment room
100 accoding to some embodiments. In accordance with some
embodiments, radiation treatment room 100 includes linear
accelerator (linac) 110, patient support 120 and operator console
130. The elements of radiation treatment room 100 may be used to
deliver radiation to a target volume of beam object 140. In this
regard, beam object 140 may comprise a patient positioned to
receive radiation according to a radiation treatment plan. The
elements of treatment room 100 may be employed in other
applications according to some embodiments.
[0054] Linac 110 generates and emits the radiation, and is
primarily composed of treatment head 111 and gantry 112. Treatment
head 111 includes a beam-emitting device (not shown) for emitting a
radiation beam used during calibration, verification, and/or
treatment. The radiation beam may comprise electron, photon or any
other type of radiation. According to some embodiments, the
radiation beam exhibits energies in the megavoltage range (i.e.
>1 MeV) and may therefore be referred to as megavoltage
radiation.
[0055] Treatment head 111 is coupled to a projection of gantry 112.
Gantry 112 is rotatable around gantry axis 113 before, during and
after radiation treatment. As indicated by arrow 114, gantry 112
may rotate clockwise or counter-clockwise according to some
embodiments. Rotation of gantry 112 serves to rotate treatment head
111 around axis 113.
[0056] Also included within treatment head 111 is a beam-shielding
device, or collimator 200 (FIG. 2) for shaping the beam and for
shielding sensitive surfaces from the beam.
[0057] During radiation treatment, a radiation beam is emitted from
treatment head 111 as a divergent beam. The beam is emitted towards
an isocenter of linac 110. The isocenter is located at the
intersection of beam axis 115 and gantry axis 113. Due to
divergence of the radiation beam and the shaping of the beam by the
aforementioned beam-shaping devices, the beam may deliver radiation
to a volume of beam object 140 rather than only to the
isocenter.
[0058] The patient support 120 supports beam object 140 during
radiation treatment. The table patient support 120 may be
adjustable to assist in positioning a treatment area of beam object
140 at the isocenter of linac 110. The patient support 120 may also
be used to support devices used for such positioning, for
calibration and/or for verification.
[0059] In some embodiments, the patient support 120 comprises a
table (sometimes referred to herein as a treatment or radiotherapy
table), a couch (sometimes referred to herein as a treatment or
radiotherapy couch) and/or any other type of structure(s) or
combination thereof.
[0060] Imaging device 116 may acquire images before, during and/or
after radiation treatment. For example, imaging device 116 may be
used to acquire images for verification and recordation of a target
volume position and of an internal patient portal to which
radiation is delivered and/or to be delivered.
[0061] In some embodiments, imaging device 116 may be attached to
gantry 112, for example, via extendible and retractable housing
117. Rotation of gantry 112 may cause treatment head 111 and
imaging device 116 to rotate around the isocenter such that
isocenter remains located between treatment head 111 and imaging
device 116 during the rotation.
[0062] In some embodiments, linac 110 is capable of producing
kilovoltage photon radiation via beamline modification or other
techniques, and imaging device 116 may acquire images based on such
kilovoltage radiation. In some embodiments, imaging device 116
comprises a system to acquire an image based on received
megavoltage photon radiation.
[0063] In some embodiments, imaging device 116 is a flat-panel
imaging device using a scintillator layer and solid-state amorphous
silicon photodiodes deployed in a two-dimensional array. In
operation, the scintillator layer receives photons and generates
light in proportion to the intensity of the received photons. The
array of photodiodes receives the light and records the intensity
of received light as stored electrical charge.
[0064] In other embodiments, imaging device 116 converts received
photons to electrical charge without requiring a scintillator
layer. The photons are absorbed directly by an array of amorphous
selenium photoconductors. The photoconductors convert the photons
directly to stored electrical charge. Imaging device 116 may also
comprise a CCD or tube-based camera. Such an imaging device may
include a light-proof housing within which are disposed a
scintillator, a mirror, and a camera.
[0065] The charge developed and stored by imaging device 116
represents radiation intensities at each location of a radiation
field produced by a beam emitted from treatment head 111. Since
object 140 is located between treatment head and imaging device
116, the radiation intensity at a particular location represents
the attenuative properties of tissues along a divergent line
between a radiation source in treatment head 111 and the particular
location. The set of radiation intensities acquired by imaging
device 116 may therefore comprise a two-dimensional projection
image of these tissues.
[0066] Operator console 130 includes input device 131 for receiving
instructions from an operator and output device 132, which may be a
monitor for presenting operational parameters of linac 110 and
imaging device 116 and/or interfaces for receiving instructions.
Output device 132 may also present a two-dimensional projection
image, a three-dimensional megavoltage (or kilovoltage) cone beam
image and/or two-dimensional "slice" images based on the
three-dimensional image.
[0067] Input device 131 and output device 132 are coupled to
processor 133 and storage 134. Processor 133 may execute program
code to perform any of the determinations and generations described
herein, and/or to cause linac 110 to perform one or more portions
of a treatment plan.
[0068] Storage 134 may store program code to generate and/or modify
a treatment plan according to some embodiments. Such code may
comprise the COHERENCE.TM. workspace or the KONRAD.TM. treatment
planning system sold by Siemens Medical Solutions. Accordingly,
storage 134 may also store radiation treatment plans in accordance
with any currently- or hereafter-known format. The treatment plans
may comprise scripts that are automatically executable by elements
of room 100 to provide radiation therapy fractions. Each fraction
of each treatment plan may require a patient to be positioned in a
particular manner with respect to treatment head 111.
[0069] Operator console 130 may be in a room other than treatment
room 100, in order to protect its operator from radiation. For
example, treatment room 100 may be heavily shielded, such as a
concrete vault, to shield the operator from radiation generated by
linac 110.
[0070] FIG. 2 is perspective view of a portion of the treatment
head 111, in accordance with some embodiments. Referring to FIG. 2,
in some embodiments, collimator 200 includes multiple leafs 202,
204 for shaping the beam and for shielding sensitive surfaces from
the beam.
[0071] FIG. 3 is a perspective view of the radiation treatment room
100 with the gantry 112 rotated, according to some embodiments.
[0072] FIG. 4 is a perspective view of a portion of the treatment
room 100 and a portion of the patient volume, in accordance with
some embodiments.
[0073] Referring to FIG. 4, in accordance with some embodiments,
the treatment room 100 may include a room co-ordinate system
includes axes Xf, Yf (113), Zf (115). A patient co-ordinate system
includes axes Xp, Yp, Zp.
[0074] In accordance with some embodiments, a circular source
trajectory is indicated at 400. A source position when the gantry
rotation is zero is indicated at 402. The source position when the
gantry rotation is an angle other than zero is indicated at
404.
[0075] In accordance with some embodiments, a collimated segment of
a beam 406 forms a pyramidal shape that intersects with the
isocentric plane to form a beam's eye view (BEV) polygon 408. Image
slices 410 may be acquired for and/or define a patient volume
412.
[0076] FIG. 5 is a block diagram of elements of treatment room 100,
according to some embodiments. The illustrated elements may be
implemented in any manner. In some embodiments, the elements are
implemented by a combination of hardware, software and/or
firmware.
[0077] Operator console 130 includes interfaces 502, 504, 506 and
508, 510 for interfacing with respective elements 200, 111, 112,
120 and 116 of treatment room 100. Each of the interfaces may
comprise any suitable type of hardware and/or software interface,
and may or may not be proprietary. Operator console 130 may control
the various elements through the interfaces and based on
instructions from processor 133.
[0078] The processor 133 may execute processor-executable process
steps stored in storage 134 to provide operation according to some
embodiments. These process steps may comprise system control
application 512 to execute one of treatment plans 514. System
control application 512 may, in some embodiments, be used to
calibrate imaging device 116, to acquire projection images, to
generate a three-dimensional image based on the projection images,
and to determine a dose based on the three-dimensional image.
Storage 134 may also comprise two and/or three-dimensional images
506 generated in conjunction with one or more process disclosed
herein.
[0079] The processor 133 and the system control application 512
may, in some embodiments, be used to execute one or more portions
of one or more of the processes disclosed herein.
[0080] A treatment system according to some embodiments may include
less or more elements than those shown in FIGS. 1-5. In addition,
embodiments are not limited to the devices and/or to the
illustrated environment. For example, some embodiments include
another type of image acquisition device to acquire projection
images.
[0081] FIG. 6 is a flow diagram of a process 600 according to some
embodiments. In some embodiments, the process 600 is used in
determining an alternative treatment plan that accounts, at least
in part, for changes in a position of a tumor or other target
volume within a patient.
[0082] The process 600 is not limited to the order shown in the
flow chart. Rather, embodiments of the process 600 may be performed
in any order that is practicable. For that matter, unless stated
otherwise, any process disclosed herein may be performed in any
order that is practicable. Moreover, some embodiments may employ
one or more portions of the process without one or more other
portions of the process.
[0083] Referring to FIG. 6, at 602 the process may include
receiving information to be used in determining an alternative
treatment plan that accounts, at least in part, for changes in a
position of a tumor or other target volume within a patient. In
some embodiments, the information may include information
indicative of (i) a treatment plan defining planned treatment
beams, (ii) a patient volume relative to a reference (i.e., patient
support, treatment room and/or other reference), (iii) ideal
intersections of the planned treatment beams with the patient
volume at the time the patient is to be treated (iv) any
constraints that prevent achievement of the recommended
repositioning using only the patient support and (v) allowable
change to the gantry position (i.e., relative to a planned value)
and allowable change to the collimator position (i.e., relative to
a planned value).
[0084] In some embodiments, the information indicative of a patient
volume relative to a reference comprises images of a patient volume
placed on the patient support prior to treatment.
[0085] In some embodiments, the information includes a
recommendation as to repositioning of the patient support to
achieve six degree of freedom correction for the changes in the
position of the tumor or other target volume within the
patient.
[0086] In some embodiments, the ideal intersections of the planned
treatment beams with the patient volume comprises ideal
intersections of the planned treatment beams with the patient
volume if the patient support is repositioned in accordance with
the recommendation as to repositioning of the patient support to
achieve six degree of freedom correction.
[0087] An ideal intersection is represented and described below
with respect to FIG. 10.
[0088] In some embodiments, the recommended repositioning of the
patient support includes a recommended translation along each of
the three orthogonal axes (i.e., a recommended translation along an
x axis, a recommended translation along a y axis and a recommended
translation along a z axis) and a recommended rotation about each
of the three orthogonal axes (i.e., a recommended rotation about
the x axis, a recommended rotation about the y axis and a
recommended rotation about the z axis) with the origin of the three
orthogonal axes disposed at the isocenter of the radiotherapy
device.
[0089] In some embodiments, each of the constraints that prevent
achievement of the recommended repositioning using only the patient
support may be defined directly. In some other embodiments, one or
more of the constraints may be defined indirectly. For example, the
information may define allowable changes to the patient support,
which if less, in any dimension, than the recommended
repositioning, indirectly defines one or more constraints that
prevent achievement of the recommended repositioning using only the
patient support.
[0090] Further in that regard, in accordance with some embodiments,
and unless stated otherwise, any type of information described
herein may be defined directly and/or indirectly.
[0091] In some embodiments, the constraints may be the same for all
beams. In some other embodiments, there may be different
constraints for different beams.
[0092] In some embodiments, the allowable changes may be the same
for all beams. In some other embodiments, there may be different
allowable changes for different beams.
[0093] At 604, the process may further include defining a plurality
of alternatives to the planned treatment plan. In some embodiments,
the alternatives are based at least in part on the constraints of
the patient support, the allowable changes to the gantry position
and the allowable changes to the collimator position. In some
embodiments, each alternative defines (i) a modified patient
support position, (ii) an amount of change to the gantry position
for each planned treatment beam, (iii) an amount of change to the
collimator position for each planned treatment beam and (iv)
modified beams.
[0094] Any method(s) may be used to define the plurality of
alternatives. In some embodiments, the alternatives are defined
using an exhaustive search that increments uniformly through a
multi-dimensional search space. In some other embodiments, a
simulated annealing and/or an xyz plug in is employed.
[0095] In some embodiments, a plurality of alternatives are
defined. One or more of the alternatives may avoid the need to
change the patient support position for each beam. This may help to
reduce the time needed to perform the treatment, as compared to the
method described above for systems that use a patient support
having only four degrees of freedom. One or more of the
alternatives may avoid any change at all to the position of the
patient support. This may help reduce the potential to disturb the
position of the patient relative to the patient support.
[0096] A table of a subset of alternatives within a search space,
in accordance with some embodiments, is described below with
respect to FIG. 11.
[0097] The modified beams may be based at least in part on a
respective one of the planned treatment beams, the change to the
position of the gantry for the respective planned treatment beam
and the change to the position of the collimator for the respective
planned treatment beam.
[0098] The modified patient support position may include a
translation for the patient support along one or more of the axes
(i.e., a translation along an x axis, a translation along a y axis
and/or a translation along a z axis) and a rotation for the patient
support about one or more of the axes (i.e., a rotation about the x
axis, a rotation about the y axis and/or a rotation about the z
axis). In some embodiments, the modified patient support position
may be the same for all alternatives. In some other embodiments,
there may be a different modified patient support position for one
or more of the alternatives. The modified patient support position
may be defined directly and/or indirectly.
[0099] In some embodiments, the amount of change to the gantry
position for a planned treatment beam may be defined relative to
the non-rotated position for the gantry or relative to the planned
position for the gantry for the planned treatment beam. In some
embodiments, each alternative may define the same amount of change
to the gantry position.
[0100] The amount of change to the collimator position for a
planned treatment beam may be defined relative to the non-rotated
position for the collimator or relative to the planned position for
the collimator for the planned treatment beam. In some embodiments,
each alternative may define the same amount of change to the
collimator position.
[0101] At 606, the process may further include determining for each
modified beam of each alternative, an intersection of the patient
volume and the modified beam, with the patient volume placed on the
patient support and having the modified patient support position
for the alternative.
[0102] An intersection of a patient volume and a modified beam, in
accordance with some embodiments, is represented and described
below with respect to FIG. 10.
[0103] In some embodiments, there may be more than one intersection
for a planned treatment beam. For example, some embodiments may use
a particular planned treatment beam with different arrangements of
collimator leafs (each arrangement of collimator leafs is sometimes
referred to as a segment). In such embodiments, there may be a
different intersection for each arrangement of collimator leafs (or
segment).
[0104] At 608, the process may further include defining, for each
alternative, a measure of difference between the ideal
intersections and the intersections for the modified beams of the
alternative.
[0105] A measure of difference between an ideal intersection and an
intersection for a modified beam is represented and described below
with respect to FIG. 10.
[0106] A process that may be used in defining the measure of
difference is described below with respect to FIG. 7.
[0107] At 610, the process may further include selecting one of the
alternatives based at least in part on the measure of difference
for the alternative. In some embodiments, this includes selecting
one of the alternatives for which the measure of difference between
the ideal intersections and the intersections for the modified
beams of the alternative is no greater than the measure of
difference between the ideal intersections and the intersections
for the modified beams of the other alternatives. In some
embodiments, the selecting of one of the alternatives is performed
by a processor. In some embodiments, the selecting of one of the
alternatives is performed by a user and/or operator. In some
embodiments, a processor receives an indication of the selection by
the user and/or operator.
[0108] In some embodiments, the process may further include
generating an ordered list of the alternatives based at least in
part on the measure of difference for each of the alternatives. In
some embodiments, this may help a user and/or operator select one
of the alternatives. In some embodiments, an alternative having a
measure of difference less than the other alternatives may be
disposed first in the ordered list. In some embodiments, the
ordered list is displayed on an output device. In some embodiments,
the output device is the same as and/or similar to the output
device 132 illustrated in FIG. 1 and/or FIG. 5. In some
embodiments, a processor generates the ordered list and receives an
indication of the selection by the user and/or operator.
[0109] The process 600 may be performed in any manner. In that
regard, in some embodiments, one or more portions of any process
disclosed herein may be performed by and/or using a processor. In
some embodiments, such processor may be the same as and/or similar
to the processor 133 illustrated in FIG. 1 and/or FIG. 5. In some
embodiments, one or more portions of any process disclosed herein
may be performed by and/or using one, some or all of the radiation
treatment devices illustrated in FIG. 1 and/or FIG. 5.
[0110] As used herein, a processor may comprise any type of
processor. For example, a processor may be programmable or non
programmable, general purpose or special purpose, dedicated or non
dedicated, distributed or non distributed, shared or not shared,
and/or any combination thereof. A processor may include, but is not
limited to, hardware, software, firmware, and/or any combination
thereof. Hardware may include, but is not limited to off the shelf
integrated circuits, custom integrated circuits and/or any
combination thereof. Software may include, but is not limited to,
instructions that are storable and/or stored on a computer readable
medium, such as, for example, punch cards, paper tape, magnetic or
optical disk, magnetic or optical tape, CD-ROM, DVD, RAM, EPROM, or
ROM. A processor may employ continuous signals, periodically
sampled signals, and/or any combination thereof. If a processor is
distributed, two or more portions of the processor may communicate
with one another through a communication link.
[0111] As used herein, a communication link may comprise any type
of communication link, for example, but not limited to wired (e.g.,
conductors, fiber optic cables) or wireless (e.g., acoustic links,
electromagnetic links or any combination thereof including, for
example, but not limited to microwave links, satellite links,
infrared links), and/or any combinations thereof. A communication
link may be public or private, dedicated and/or shared (e.g., a
network) and/or any combination thereof. A communication link may
or may not be a permanent communication link. A communication link
may support any type of information in any form, for example, but
not limited to, analog and/or digital (e.g., a sequence of binary
values, i.e. a bit string) signal(s) in serial and/or in parallel
form. The information may or may not be divided into blocks. If
divided into blocks, the amount of information in a block may be
predetermined or determined dynamically, and/or may be fixed (e.g.,
uniform) or variable. A communication link may employ a protocol or
combination of protocols including, for example, but not limited to
the Internet Protocol.
[0112] Software that includes instructions to be executed by a
processor to perform one or more portions of one or more processes
may be stored by any processor readable medium, for example, punch
cards, paper tape, magnetic or optical disk, magnetic or optical
tape, CD-ROM, DVD, RAM, EPROM, or ROM. The processor readable
medium may be and/or may be included in, an article of
manufacture.
[0113] FIG. 7 is a flow diagram of a process 700 according to some
embodiments. In some embodiments, one or more portions of the
process 700 are used at 608 (FIG. 6) in defining a measure of
difference between the ideal intersections and the intersections
for the modified beams of an alternative.
[0114] Referring to FIG. 7, at 702, the process may include
defining, for each modified beam of the alternative, a measure of
difference between the intersection and a respective one of the
ideal intersections. In some embodiments, the measure of difference
between each intersection and the respective ideal intersection is
based at least in part on a distance between a point defined by the
intersection and a corresponding point defined by the respective
ideal intersection.
[0115] A process that may be used at 702 is described below with
respect to FIG. 8.
[0116] At 704, the process may further include defining a measure
of difference between the ideal intersections and the intersections
for the modified beams of the alternative based at least in part on
the measure of difference between the intersection and the
respective one of the ideal intersections for each modified beam of
the alternative.
[0117] A process that may be used at 704 is described below with
respect to FIG. 9.
[0118] FIG. 8 is a flow diagram of a process 800 according to some
embodiments. In some embodiments, one or more portions of the
process 800 are used at 702 (FIG. 7) in defining the measure of
difference between an intersection and the respective ideal
intersection.
[0119] Referring to FIG. 8, at 802, the process may include
defining each intersection as a pyramid having a tip and a base.
The base may comprise a polygonal shape having a plurality of
corners.
[0120] At 804, the process may further include defining a distance
between the tip of the intersection for the modified beam and the
tip of the respective ideal intersection.
[0121] At 806, the process may further include defining for each
corner of the intersection, a distance between the corner and a
corresponding corner of the respective ideal intersection.
[0122] At 808, the process may further include defining a square of
the distance between the tips.
[0123] At 810, the process may further include defining a square of
the distance defined for each corner.
[0124] At 812, the process may further include defining the measure
of difference between an intersection and the respective ideal
intersection based at least in part on a sum of the square of the
distance between the tips and the square of the distance defined
for each corner of the polygon.
[0125] FIG. 9 is a flow diagram of a process 900 according to some
embodiments. In some embodiments, one or more portions of the
process 900 are used at 704 (FIG. 7) in defining the measure of
difference between the ideal intersections and the intersections
for the modified beams of the alternative.
[0126] Referring to FIG. 9, at 902, the process may include
defining, for each modified beam of the alternative, a measure of
difference between the intersection and a respective one of the
ideal intersections.
[0127] At 904, the process may further include defining, for each
modified beam of the alternative, a weighted difference defined as
a product of a weight and the measure of difference between the
intersection and a respective one of the ideal intersections. In
some embodiments, the weight is based at least in part on a
dosimetric strength of the modified beam relative to respective
dosimetric strengths of the other modified beams of the
alternative.
[0128] In accordance with some embodiments, the dosimetric strength
of each modified beam may be defined in direct or indirect terms.
In some embodiments, the dosimetric strength of each modified beam
is defined in terms of the dose of each modified beam. In some
other embodiments, the dosimetric strength of each modified beam is
defined in terms of a field/segment area or any function of jaw
settings etc. of each modified beam.
[0129] At 906, the process may further include defining the measure
of difference between the ideal intersections and the intersections
for the modified beams based at least in part on the weighted
difference for each modified beam of the alternative. In some
embodiments, the measure of difference between the ideal
intersections and the intersections for the modified beams is based
at least in part on the sum of the weighted difference for each
modified beam of the alternative.
[0130] FIG. 10 is a diagrammatic representation 1000 of an ideal
intersection and a modified intersection, in accordance with some
embodiments.
[0131] Referring to FIG. 10, the diagrammatic representation 1000
includes first, second and third coordinate systems. The first
coordinate system 1002 is an international electrotechnical
commission (IEC) fixed (world) coordinate system. The second
coordinate system 1004 is a patient coordinate system, shown with
respect to the IEC fixed coordinate system, after a six degree of
freedom patient set up correction using a robotic patient support.
The third coordinate system 1006 is a patient coordinate system,
with respect to the IEC coordinate system, with an alternative set
up correction that includes a modified patient support position
made up of patient support translation and patient support
rotation, a change in the gantry position and a change in the
collimator position.
[0132] The representation further includes a planned beam (shown
with a source at 1008) and an ideal intersection 1010 (shown
expressed in the patient co-ordinate system 1004), in accordance
with some embodiments. The planned beam is a beam that would result
if the six degree of freedom patient set up correction is provided.
The ideal intersection 1010 is the intersection of the planned beam
and the patient volume. In accordance with some embodiments, the
ideal intersection 1010 defines a pyramid having a tip (at the
source 1008) and a base 1011 (in the isocentric plane). In
accordance with some embodiments, the base 1011 is defined as a
polygon having a plurality of corners, e.g., corners 1012-1026.
[0133] The representation further includes a modified beam (with a
source at 1028) and a modified intersection 1030 (shown expressed
in the patient co-ordinate system 1006), in accordance with some
embodiments. The modified beam is a beam that would result if the
alternative patient set up correction is provided. The modified
intersection 1030 is the intersection of the modified beam and the
patient volume. In accordance with some embodiments, the modified
intersection 1030 defines a pyramid having a tip (at the source
1028) and a base 1031 (in the isocentric plane). In accordance with
some embodiments, the base 1031 is defined as a polygon having a
plurality of corners, e.g., corners 1032-1046.
[0134] In some embodiments, the arrangement of the collimator leafs
for the planned beam is the same as the arrangement of the
collimator leafs for the modified beam. Thus, the aperture may have
the same shape for the planned beam and the modified beam.
[0135] A distance 1048 is shown between the tip of the modified
intersection 1030 and the tip of the ideal intersection 1010.
[0136] A distance is also shown between each corner of the modified
intersection 1030 and a corresponding corner of the ideal
intersection 1010, i.e., a distance 1052 between corner 1032 of
modified intersection 1030 and corner 1012 of ideal intersection
1010, a distance 1054 between corner 1034 of modified intersection
1030 and corner 1014 of ideal intersection 1010, a distance 1056
between corner 1036 of modified intersection 1030 and corner 1016
of ideal intersection 1010, a distance 1058 between corner 1038 of
modified intersection 1030 and corner 1018 of ideal intersection
1010, a distance 1060 between corner 1040 of modified intersection
1030 and corner 1020 of ideal intersection 1010, a distance 1062
between corner 1042 of modified intersection 1030 and corner 1022
of ideal intersection 1010, a distance 1064 between corner 1044 of
modified intersection 1030 and corner 1024 of ideal intersection
1010 and a distance 1066 between corner 1046 of modified
intersection 1030 and corner 1026 of ideal intersection 1010.
[0137] In some embodiments, a measure of difference between the
modified intersection 1030 and the ideal intersection 1010 may be
defined as a sum of squares of distances 1048-1066.
[0138] In some embodiments, a measure of difference between the
modified intersection 1030 and the ideal intersection 1010 may be
defined as a product of a dosimetric strength and a sum of squares
of distances 1048-1066.
[0139] In some embodiments, a measure of difference between the
modified intersection 1030 and the ideal intersection 1010 may be
defined as a product of the planned dose of the beam 1008 and the
sum of squares of distances 1048-1066.
[0140] FIG. 11 is a table 1100 of a subset of the possible
alternatives for a treatment plan having four beams, in accordance
with some embodiments.
[0141] Referring to FIG.11, the subset of the possible alternatives
include a first alternative 1101, a second alternative 1102, a
third alternative 1103, and so on. In accordance with some
embodiments, each alternative defines five dimensions, i.e., a
modified patient support position, an amount of change to the
gantry position and an amount of change to the collimator position
for each of the four beams. In accordance with some embodiments,
the modified patient support position includes an amount of
translation along an x-axis, an amount of translation along a
y-axis, an amount of translation along a z-axis and an amount of
rotation about one of the axes.
[0142] In accordance with some embodiments, the search space has a
range of .+-.5 mm for the translation along the x axis, a range of
.+-.5 mm for the translation along the y axis, a range of .+-.5 mm
for the translation along the z axis, .+-.5 degrees for the change
in the gantry position and .+-.5 degrees for the change in the
collimator position. FIG. 11 does not show the portion of the
search space covering the negative portion of the ranges. In
accordance with some embodiments, the increment amount is uniform
and equal to .+-.1.
[0143] In some embodiments, the number of possible alternatives
will be equal to the total number of different possible
combinations.
[0144] In some embodiments, the number of dimensions in the search
space depends at least in part on the constraints that prevent
achievement of the recommended repositioning using only the patient
support.
[0145] In some embodiments, the number of dimensions are defined
based on the allowable changes to the patient support (and/or other
structures coupled to a patient), the allowable changes to the
gantry position and the allowable changes to the collimator
position. In some embodiments, the number of dimensions are defined
as a sum of a degrees of freedom represented by the allowable
changes to the patient support (and/or other structures coupled to
a patient), a degrees of freedom represented by the allowable
changes to the gantry position and a degrees of freedom represented
by the allowable changes to the collimator position.
[0146] In some embodiments, a plurality of alternatives are
defined. One or more of the alternatives may avoid the need to
change the patient support position for each beam. This may help to
reduce the time needed to perform the treatment, as compared to the
method described above for systems that use a patient support
having only four degrees of freedom. One or more of the
alternatives may avoid any change at all to the position of the
patient support. This may help reduce the potential to disturb the
position of the patient relative to the patient support.
[0147] In some embodiments, the range for a dimension in the search
space is selected based at least in part on the change in position
of the tumor or other target volume in that dimension. In some
embodiments, a greater change in position in a dimension may result
in a greater range for that dimension in the search space.
[0148] FIGS. 12A-12D are a flow diagram of a process 1200 that may
use and/or be used by processes 600-900, according to some
embodiments.
[0149] Referring to FIGS. 12A-12D, at 1202, the process may include
receiving images of a patient volume (CT.sub.P) used in defining a
treatment plan. In some embodiments, receiving the images comprises
fetching the images from storage and loading the image into memory.
In some embodiments, the images comprise computer tomography images
acquired during planning.
[0150] At 1204, the process may further include receiving images of
patient volume (CT.sub.N) immediately prior to a treatment. In some
embodiments, the images comprise computer tomography images.
[0151] At 1206, the process may further include registering the
images of the patient volume (CT.sub.P) to the images of patient
volume (CT.sub.N) to determine an initial affine registration. In
some embodiments, this may be carried out using an affine
registration service, intensity difference optimizers, cross
correlation, and/or xyz plug in. In some embodiments, the initial
affine registration defines a recommendation for setup correction.
In some embodiments, the initial affine registration is in the form
of a 4.times.4 matrix.
[0152] At 1208, the process may further include determining whether
the registration is satisfactory. If the registration is not
satisfactory, at 1210, the process may further include performing a
manual six degree of freedom adjustment of the images of the
patient volume (CT.sub.P) to the images of patient volume
(CT.sub.N).
[0153] If the registration is satisfactory at 1208, then at 1212,
the process may further include determining a six degree of freedom
correction. If the initial affine registration is in the form of a
4.times.4 matrix, this may include decomposing the 4.times.4 matrix
into the six degree of freedom correction.
[0154] At 1214, the process may further include receiving
information defining allowable changes to a patient support.
[0155] At 1216, the process may further include receiving
information defining allowable changes to a delivery device. In
some embodiments the information defines allowable changes to a
gantry position and allowable changes to a collimator position.
[0156] At 1218, the process may further include defining a number
of dimensions for a search space. In some embodiments, the number
of dimensions are defined based on the allowable changes to the
patient support, the allowable changes to the gantry position and
the allowable changes to the collimator position. In some
embodiments, the number of dimensions are defined as a sum of a
degrees of freedom represented by the allowable changes to the
patient support, a degrees of freedom represented by the allowable
changes to the gantry position and a degrees of freedom represented
by the allowable changes to the collimator position.
[0157] In some embodiments, 1214-1218 are performed before and/or
during 1202-1212.
[0158] At 1220, the process may further include receiving
information that defines treatment beams of a treatment plan. In
some embodiments, receiving may comprise fetching from storage and
loading in memory. In some embodiments, the information includes an
intensity, gantry position (angle), collimator position (angle),
and position/shape of leafs that form the collimator, for each beam
of the treatment plan.
[0159] At 1222, the process may further include defining each
aperture `A` as discrete points on a polygon.
[0160] In some embodiments, 1220-1222 are performed before and/or
during 1202-1212 and/or 1214-1218.
[0161] At 1224, the process may further include defining
alternative.sub.0 as an alternative having no set-up correction,
(e.g., no changes to the patient support position, no changes to
the gantry position and no changes to the collimator position).
[0162] The process may further include determining an error
associated with alternative.sub.0. In some embodiments, this
includes determining the error associated with each aperture of
each gantry position.
[0163] The error associated with alternatives may thereafter be
determined as a weighted sum of all the errors (i.e., a weighted
sum of the error for each aperture of each gantry position). In
some embodiments, the error for each aperture is weighted equally.
In some other embodiments, the error for each aperture is weighted
in accordance with the relative intensity of the intensity of the
beam for that aperture.
[0164] In some embodiments, the processes 600-900 are used at 1224
in determining the error.
[0165] At 1226, the process may further include defining the error
associated with alternative.sub.0 as 0% correction.
[0166] At 1228, the process may further include defining other
alternatives and determining an error and % correction for each of
such alternatives.
[0167] Any method(s) may be used to define the plurality of
alternatives. In some embodiments, the alternatives are defined
using an exhaustive search that increments uniformly through a
multi-dimensional search space. In some other embodiments, a
simulated annealing and/or an xyz plug in is employed.
[0168] In some embodiments, a plurality of alternatives are
defined. One or more of the alternatives may avoid the need to
change the patient support position for each beam. This may help to
reduce the time needed to perform the treatment, as compared to the
method described above for systems that use a patient support
having only four degrees of freedom. One or more of the
alternatives may avoid any change at all to the position of the
patient support. This may help reduce the potential to disturb the
position of the patient relative to the patient support.
[0169] A table of some alternatives within a search space, in
accordance with some embodiments, is described above with respect
to FIG. 11.
[0170] In some embodiments, the error for each alternative is
determined in a manner similar to that described above for
alternative.sub.0. In some embodiments, zero error is defined as
100% correction and the % correction associated with an alternative
is determined as 100% multiplied by the difference between the
error for the alternative and the error for alternatives.
[0171] In some embodiments, the processes 600-900 are used at 1228
in determining the errors.
[0172] At 1230, the process may further include displaying the %
correction for each alternative. The alternatives may also be
displayed. In some embodiments, this may include displaying the
alternatives and the % correction for each alternative in an
ordered list. In some embodiments, the ordering of the alternatives
in the ordered list is based at least in part on the % correction
for the alternatives. In some embodiments, an alternative having a
% correction greater than the other alternatives may be disposed
first in the ordered list. In some embodiments, the ordered list is
displayed on an output device. In some embodiments, the output
device is the same as and/or similar to the output device 132
illustrated in FIG. 1 and/or FIG. 5.
[0173] At 1232, the process may further include selecting an
alternative and evaluating the beam geometry of the alternative
with the anatomy in the images of patient volume (CT.sub.N). In
some embodiments the beam geometry includes an intensity, gantry
position (angle), collimator position (angle), and position/shape
of leafs that form the collimator, for each beam of the
alternative.
[0174] In some embodiments, the selecting of an alternative is
performed by a processor. In some embodiments, the selecting of an
alternative is performed by a user and/or operator.
[0175] At 1234, the process may further include determining whether
the beam geometry of the alternative is satisfactory. If not
satisfactory, at 1236, the method may further include performing a
manual adjustment.
[0176] If the beam geometry is satisfactory at 1234, then at 1238,
the process may further include incorporating the selected
alternative into the treatment plan. In some embodiments, this may
include remotely programming changes in the positions as defined by
the selected alternative.
[0177] At 1240, the process may further include initiating
treatment with the changes in positions defined the selected
alternative.
[0178] As stated above, in some embodiments the process 1200 may
use and/or be used by processes 600-900.
[0179] In some embodiments, one or more portions of processes
600-900 and/or 1200 may be performed after a patient has been
placed on a patient support and is awaiting treatment.
[0180] Those in the art will appreciate that various adaptations
and modifications of the above-described embodiments can be
configured without departing from the scope and spirit of the
claims. Therefore, it is to be understood that the claims may be
practiced other than as specifically described herein.
* * * * *