U.S. patent application number 15/196140 was filed with the patent office on 2017-01-05 for particle beam therapy system.
The applicant listed for this patent is Hitachi, Ltd.. Invention is credited to Tatsuya FUJISAWA, Takenori NISHIMURA, Tsutomu YAMASHITA.
Application Number | 20170001041 15/196140 |
Document ID | / |
Family ID | 57683248 |
Filed Date | 2017-01-05 |
United States Patent
Application |
20170001041 |
Kind Code |
A1 |
YAMASHITA; Tsutomu ; et
al. |
January 5, 2017 |
PARTICLE BEAM THERAPY SYSTEM
Abstract
A particle therapy system has an irradiation system attached to
a rotary drum of a gantry. A radiation treatment cage disposed in
the rotary drum includes a movable floor including a horizontal
floor portion. The movable floor includes a number of footboards
connected bendably and X-ray transmission plates. The movable floor
has a slide member at each end thereof, and the slide member is
movably attached to a guide rail that is provided for each of
opposite side surfaces of the irradiation system. X-ray sources are
disposed outside the rotary drum apart from each other in a
circumferential direction of the rotary drum and attached to the
outer surface of the rotary drum. The irradiation system includes
X-ray detection systems opposite to the X-ray sources.
Inventors: |
YAMASHITA; Tsutomu; (Tokyo,
JP) ; FUJISAWA; Tatsuya; (Tokyo, JP) ;
NISHIMURA; Takenori; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi, Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
57683248 |
Appl. No.: |
15/196140 |
Filed: |
June 29, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 2005/1061 20130101;
A61N 5/1049 20130101; A61N 2005/1087 20130101; A61N 5/1081
20130101 |
International
Class: |
A61N 5/10 20060101
A61N005/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2015 |
JP |
2015-131407 |
Claims
1. A particle therapy system comprising: a gantry; an irradiation
system which is attached to the gantry and to which an ion beam is
incident; a treatment cage installed in the gantry, having an orbit
including an arc-like portion and a horizontal portion
communicating with the arc-like portion, and including a
surrounding member formed by a plurality of connected footboard
members and capable of moving along the orbit; an X-ray source
disposed outside the surrounding member and attached to the gantry;
and an X-ray detection system disposed inside the surrounding
member, attached to the irradiation system, and detecting an X-ray
from the X-ray source, wherein the surrounding member includes an
X-ray transmission member disposed between the adjacent footboard
members, connected to the each of the adjacent footboard members,
disposed between the X-ray source and the X-ray detection system,
and transmitting an X-ray emitted from the X-ray source.
2. The particle therapy system according to claim 1, wherein a
width W.sub.2 of the X-ray transmission member in a circumferential
direction of the gantry is larger than a width W.sub.1 of the
footboard member in the circumferential direction and is less than
or equal to a value obtained by subtracting the width W.sub.1 from
a width W.sub.H of a horizontal floor portion of the surrounding
member that is located in the horizontal portion of the orbit.
3. The particle therapy system according to claim 2, wherein the
X-ray transmission member includes an X-ray transmission region and
a plate-shaped metal member and a width W.sub.3 of the X-ray
transmission region in the circumferential direction is smaller
than the width W.sub.2 of the X-ray transmission member.
4. The particle therapy system according to claim 1, wherein: the
X-ray source is disposed outside the gantry and attached to an
outer surface of the gantry; and an X-ray transmission hole is
formed at a position on the gantry opposite to the X-ray
source.
5. The particle therapy system according to claim 1, wherein the
X-ray source includes a first X-ray source and a second X-ray
source; the first X-ray source and the second X-ray source are
disposed apart from each other in a circumferential direction of
the gantry; the X-ray detection system includes a first X-ray
detection system and a second X-ray detection system; the first
X-ray detection system is disposed opposite to the first X-ray
source; and the second X-ray detection system is disposed opposite
to the second X-ray source.
6. The particle therapy system according to claim 5, wherein the
X-ray transmission member includes a first X-ray transmission
member and a second X-ray transmission member; the first X-ray
transmission member is disposed opposite to the first X-ray source;
and the second X-ray transmission member is disposed opposite to
the second X-ray source.
7. The particle therapy system according to claim 1, wherein a
width W.sub.2 of each of the first and second X-ray transmission
members in a circumferential direction of the gantry is larger than
a width W.sub.1 of the footboard member in the circumferential
direction and is less than or equal to a value obtained by
subtracting the width W.sub.1 from a width W.sub.H of the
horizontal floor portion of the surrounding member that is located
in the horizontal portion of the orbit.
8. The particle therapy system according to claim 7, wherein each
of the first and second X-ray transmission members includes an
X-ray transmission region and a plate-shaped metal member and a
width W.sub.3 of the X-ray transmission region in the
circumferential direction is smaller than the width W.sub.2 of the
X-ray transmission member.
9. The particle therapy system according to claim 1, further
comprising a pair of connectors provided for the irradiation
system, the connector connecting between each of opposite ends of
the surrounding member and each of a pair of opposite side surfaces
of the irradiation system in a manner that movement in a radial
direction of the gantry is possible.
10. The particle therapy system according to claim 9, wherein the
connector comprises a guide member attached to the side surface of
the irradiation system and extending in the radial direction of the
gantry, and a slide member attached to the end of the movable floor
member and attached movably to the guide member.
11. The particle therapy system according to claim 9, wherein the
pair of side surfaces of the irradiation system opposite to each
other in the rotating direction of the gantry is tapered toward a
center axis of the gantry.
12. The particle therapy system according to claim 6, wherein the
surrounding member includes a first movable floor portion including
a plurality of footboard members connected bendably and the second
X-ray transmission member, and a second movable floor portion
including a plurality of footboard members connected bendably and
the first X-ray transmission member.
13. The particle therapy system according to claim 9, further
comprising a cover that closes an opening generated in the
surrounding member, and a cover winding system that moves the
cover.
14. The particle therapy system according to claim 1, further
comprising an accelerator that accelerates the ion beam, and a beam
transport that is connected to the accelerator and guides the ion
beam from the accelerator to the irradiation system.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a particle therapy system
suitably used for treating cancer with a particle beam, which is
one kind of radiation.
[0003] 2. Description of the Related Art
[0004] Particle therapy systems that deliver a particle beam
(proton or baryon beam) to a target volume in accordance with its
position and shape have been used in, for example, cancer
treatment.
[0005] Known particle therapy systems are roughly classified into
particle therapy systems with a synchrotron as an accelerator (for
example, JP-2004-358237-A) and particle therapy systems with a
cyclotron as an accelerator (for example, JP-2011-92424-A). The
particle therapy system with the synchrotron and the particle
therapy system with the cyclotron both have a gantry provided with
an irradiation system.
[0006] For the particle therapy to be efficiently conducted, it is
necessary to deliver the particle beam to the cancer lesion with
high accuracy, and in view of this, particle therapy systems with
the structure that enables to set the irradiation system to the
optimum irradiation point of the patient have been developed. The
particle therapy on the patient from any direction with such a
particle therapy system requires a gantry system capable of
rotating around the patient by 360.degree. and a radiation
treatment cage (hereinafter referred to as treatment cage) that
operates synchronizing with the rotation.
[0007] An example of the gantry with the treatment cage has been
disclosed in JP-H-11-47287-A. The treatment cage includes a movable
floor, and a rotatable-side ring rail and a fixed-side ring rail
disposed inside the gantry and attached to the gantry. The
fixed-side ring rail and the rotatable-side ring rail have, on
their opposite surfaces, a semi-cylindrical orbit that guides the
movable floor. The movable floor includes a number of footboards
that are connected with each other in such a manner that the
footboards can be freely bent, and the movable floor moves along
the semi-cylindrical orbit synchronizing with the rotation of the
gantry. Because of the semi-cylindrical orbit, a horizontal floor
portion (access floor) is formed by some footboards of the movable
floor. The horizontal floor portion enables a medical practitioner
(for example, a doctor or a medical technician) to stand on the
horizontal floor portion and easily access the patient on the
treatment stand inserted into the treatment cage.
[0008] An example of the treatment cage installed in the gantry has
been disclosed in JP-2011-156263-A. In this treatment cage, the
slide members provided at the opposite ends of the movable floor in
the circumferential direction of the gantry are slidably attached
to a pair of guide rails, which serves as the guide member and is
provided for the two side surfaces of the irradiation system
attached to the gantry opposite to each other in the rotating
direction of the gantry.
[0009] JP-2008-544833-T has disclosed in FIG. 10A, FIG. 10B, and
FIG. 10C, the radiation therapy system where the image of the
patient is formed while the radiation process is carried out. For
forming the image, a pair of X-ray sources that emits the X-rays
toward a first imaging center and another pair of X-ray sources
that emits the X-rays toward a second imaging center are installed
within a depression provided for the floor of the operating room
and below the floor surface, and the X-ray transparent material is
attached to the floor surface covering these X-ray sources.
[0010] Moreover, JP-H-1-209077-A has disclosed one example of
positioning the target volume relative to the irradiation system.
In this positioning method, the amount of movement of the bed for
positioning the target volume is calculated using the reference
image information formed based on the tomographic information
obtained from the X-ray computed tomography system in advance
before the position of the target volume and the current X-ray
image information in the orthogonal two directions formed based on
the X-ray detection signals from the X-ray detection system having
detected the X-ray emitted from the X-ray source provided for the
irradiation system and transmitted through the target volume of the
patient on the bed before the irradiation with the ion beam. Based
on the calculated amount of movement of the bed, the bed is moved
manually to determine the position of the target volume relative to
the irradiation system. According to JP-H-1-209077-A, the bed may
be moved automatically based on the calculated amount of movement
of the bed.
[0011] According to JP-2006-239403-A, the amount of movement of the
bed and the rotation angle of the bed are calculated and based on
the calculated amount of movement and rotation angle, the target
volume is automatically positioned relative to the irradiation
system by the bed controller. In JP-2006-239403-A, the target
volume is positioned using the reference tomographic information of
the target volume obtained from the X-ray computed tomography in
advance and the current tomographic image information formed based
on the output signals from the X-ray detection system obtained by
detecting the X-ray emitted from the X-ray source provided for the
irradiation system attached to the gantry and transmitting through
the patient on the treatment stand while the gantry is rotated.
SUMMARY OF THE INVENTION
[0012] In the particle therapy system including the treatment cage
with the movable floor having the positioning driver, the patient
on the bed needs to be positioned to the isocenter (bed
positioning) after the operation of positioning the treatment cage
is completed. In one way of the bed positioning, the X-ray
generator and the X-ray detection system (for example, FPD) mounted
on the positioning driver provided in the axis direction of the
gantry are pulled out to the position of the isocenter and then the
patient on the bed is X-rayed.
[0013] In the case of using such a positioning driver, however, the
operation speed is required to be 100 mm/sec or less from the
safety point of view because the operation distance of the X-ray
generator is several meters (for example, about 1.8 meters). For
this reason, just operating the positioning driver may take ten and
several seconds (about 18 seconds). In addition, for the precise
positioning, a plurality of such positioning drivers is mounted. If
the plural positioning drivers cannot be operated at the same time,
the time required for positioning is multiplied by the number of
drivers and this is a major issue in improving the treatment
throughput.
[0014] In one structure to improve the treatment throughput, the
movable floor is omitted and a polygonal fixed floor is provided
for the treatment cage, and the X-ray generator and the X-ray
detection system are fixed at the position where the center axis of
the gantry is sectioned at the position of the isocenter. In such a
structure, the operation of the positioning driver is not
necessary, so that the operation time of the positioning driver is
zero, thereby shortening the positioning time. However, the
horizontal floor of the treatment cage is formed at a certain pitch
in accordance with the number of corners of the polygon and
moreover, the treatment cage cannot be increased in size. These
facts interrupt the medical practitioner's easy access to the
patient.
[0015] An object of the present invention is to provide a particle
therapy system that enables the medical practitioner to access the
patient easily and improves the treatment throughput.
[0016] A feature of the present invention for achieving the object
is to include: a gantry; an irradiation system which is attached to
the gantry and to which an ion beam is incident; a treatment cage
installed in the gantry, having an orbit including an arc-like
portion and a horizontal portion communicating with the arc-like
portion, and including a surrounding member formed by a plurality
of connected footboard members and capable of moving along the
orbit; an X-ray source disposed outside the surrounding member and
attached to the gantry; and an X-ray detection system disposed
inside the surrounding member, attached to the irradiation system,
and detecting an X-ray from the X-ray source, and the surrounding
member includes an X-ray transmission member disposed between the
adjacent footboard members, connected to the each of the adjacent
footboard members, disposed between the X-ray source and the X-ray
detection system, and transmitting an X-ray emitted from the X-ray
source.
[0017] The surrounding member moving along the orbit including the
arc-like portion and the horizontal portion communicating with this
arc-like portion forms the horizontal floor portion in the
horizontal portion of the orbit. A medical practitioner can stand
on the horizontal floor portion and can easily access the patient
on the bed inserted into the surrounding member. The X-ray source
is attached to the gantry, and the X-ray detection system that
detects the X-ray from this X-ray source is attached to the
irradiation system. This configuration eliminates the necessity of
moving the X-ray source and the X-ray detection system in the axial
direction of the gantry in X-raying the target volume. Thus, the
time required to start X-raying the target volume can be shortened.
This can improve the treatment throughput.
[0018] Preferably, the X-ray source is disposed outside the gantry
and attached to the outer surface of the gantry and the X-ray
transmission hole is formed at the position of the gantry opposite
to the X-ray source.
[0019] According to the present invention, the medical practitioner
can access the patient easily and the treatment throughput can be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a structure diagram illustrating a particle
therapy system according to a first embodiment corresponding to a
preferred embodiment of the present invention;
[0021] FIG. 2 is a magnified longitudinal sectional diagram of a
gantry illustrated in FIG. 1;
[0022] FIG. 3 is a diagram viewed from arrows III-III in FIG.
2;
[0023] FIG. 4 is a magnified perspective view of a radiation
treatment cage illustrated in FIG. 2 and FIG. 3;
[0024] FIG. 5 is a plan view of a footboard illustrated in FIG.
4;
[0025] FIG. 6 is a plan view of an X-ray transmission plate
illustrated in FIG. 4;
[0026] FIG. 7 is a diagram for describing the state of the movable
floor of the radiation treatment cage when the rotation angle of
the gantry illustrated in FIG. 2 and FIG. 3 is 0.degree.;
[0027] FIG. 8 is a diagram for describing the state of the movable
floor of the radiation treatment cage when the rotation angle of
the gantry illustrated in FIG. 2 and FIG. 3 is 135.degree.;
[0028] FIG. 9 is a diagram for describing the state of the movable
floor of the radiation treatment cage when the rotation angle of
the gantry illustrated in FIG. 2 and FIG. 3 is 180';
[0029] FIG. 10 is a diagram illustrating how easily the medical
practitioner on the horizontal floor portion of the movable floor
can access the patient on the treatment stand in the particle
therapy system according to the first embodiment;
[0030] FIG. 11 is a diagram illustrating the positions of the X-ray
transmission plates in the radiation treatment cage and the
positions of the X-ray transmission on the X-ray transmission
plates when the rotation angle of the gantry illustrated in FIG. 2
and FIG. 3 is 0.degree.;
[0031] FIG. 12 is a diagram illustrating the positions of the X-ray
transmission plates in the radiation treatment cage and the
positions of the X-ray transmission on the X-ray transmission
plates when the rotation angle of the gantry illustrated in FIG. 2
and FIG. 3 is 90.degree.;
[0032] FIG. 13 is a diagram illustrating the positions of the X-ray
transmission plates in the radiation treatment cage and the
positions of the X-ray transmission on the X-ray transmission
plates when the rotation angle of the gantry illustrated in FIG. 2
and FIG. 3 is 180.degree.;
[0033] FIG. 14 is a diagram for describing the state of the movable
floor of the radiation treatment cage when the rotation angle of
the gantry is 0.degree. in a particle therapy system according to a
second embodiment corresponding to another preferred embodiment of
the present invention;
[0034] FIG. 15 is a diagram for describing the state of the movable
floor of the radiation treatment cage when the rotation angle of
the gantry is 135.degree. in the particle therapy system according
to the second embodiment; and
[0035] FIG. 16 is a structure diagram illustrating a particle
therapy system according to a third embodiment corresponding to
another preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Embodiments of the present invention will hereinafter be
described.
First Embodiment
[0037] A particle therapy system according to a first embodiment
corresponding to a preferred embodiment of the present invention
will hereinafter be described with reference to FIG. 1 to FIG.
4.
[0038] A particle therapy system 1 according to this embodiment is
installed in a building (not illustrated), specifically on a floor
surface of the building. This particle therapy system 1 includes,
as illustrated in FIG. 1, an ion beam generator 2, a high energy
beam transport (HEBT) 15, a gantry beam transport (GABT) 20, a
gantry 28, and an irradiation system 57. The particle therapy
system 1 employs a proton ion beam as the ion beam to be delivered
to the target volume of the cancer (beam delivery target). A carbon
ion beam may be employed instead of the proton ion beam.
[0039] The ion beam generator 2 includes an ion source (not
illustrated), and a linear accelerator 14 and a synchrotron
accelerator 3 corresponding to a preaccelerator. The synchrotron
accelerator 3 includes a circular beam duct 4 constituting the
circulating orbit of the ion beam, an injector 5, a radiofrequency
acceleration cavity (radiofrequency accelerator) 8 that applies
radiofrequency voltage to the ion beam, a plurality of bending
magnets 6, a plurality of quadrupole magnets 7, an extraction
radiofrequency application system 9, and an extraction septum
magnet 13. The injector 5 communicating with the beam duct 4 is
connected to the linear accelerator 14 through a vacuum duct. The
ion source is also connected to the linear accelerator 14. The
radiofrequency application system 9 includes an extraction
radiofrequency electrode 10, a radiofrequency power source 11, and
an opening/closing switch 12. The extraction radiofrequency
electrode 10 is attached to the circular beam duct 4, and is
connected to the radiofrequency power source 11 through the
opening/closing switch 12. The bending magnets 6, the quadrupole
magnets 7, the radiofrequency acceleration cavity 8, and the septum
magnet 13 are disposed along the beam duct 4 as illustrated in FIG.
1.
[0040] The HEBT (first beam transport) 15 includes a beam path
(beam duct) 16 connected to the septum magnet 13 of the synchrotron
accelerator 3, and is configured to have a plurality of quadrupole
magnets 18, a bending magnet 17, and a plurality of quadrupole
magnets 19 disposed along the beam path 16 in a direction from the
synchrotron accelerator 3 to the irradiation system 57.
[0041] The GABT (second beam transport) 20 includes a beam path
(beam duct) 21, and is configured to have a bending magnet 22,
quadrupole magnets 25 and 26, and bending magnets 23 and 24
disposed along the beam path 21 in a direction from the synchrotron
accelerator 3 to the irradiation system 57. The beam path 21 and
the magnets of the GABT 20 are attached to the gantry 28. The beam
path 21 communicates with the beam path 16 in a scramble portion 27
between the HEBT 15 and the GABT 20. The beam path 21 is rotated by
the gantry 28; for this reason, the beam path 21 is not directly
connected to the beam path 16.
[0042] The irradiation system 57 includes two scanning magnets (ion
beam scanning systems) 58 and 59, a beam position monitor 60, and a
dose monitor 61. The irradiation system 57 is attached to the
gantry 28 in the downstream side relative to the bending magnet 24.
The scanning magnets 58 and 59, the beam position monitor 60, and
the dose monitor 61 are disposed in this order along a center axis
97 of the irradiation system 57 in a direction from the bending
magnet 24 to the ion beam exit of the irradiation system 57. The
scanning magnet 58 scans the ion beam in the X direction while
having the ion beam bent within a plane perpendicular to the center
axis 97 of the irradiation system 57, and the scanning magnet 59
scans the ion beam in the Y direction orthogonal to the X direction
while having the ion beam bent within that plane. A treatment stand
62 on which a patient 70 lies down is disposed opposite to the end
of the irradiation system 57.
[0043] The gantry 28 is described with reference to FIG. 2 and FIG.
3. The gantry 28 includes a semi-cylindrical rotary drum 29
including a front ring 30 and a rear ring 31. The front ring 30 is
supported by a support system 32A installed on a floor 72 of the
building, and the rear ring 31 is supported by a support system 32B
installed on the floor 72. The support system 32A includes a pair
of roll supporters 33 and a plurality of support rollers 34A. The
support rollers 34A are attached rotatably to each of the roll
supporters 33. The front ring 30 is supported by these support
rollers 34A. Like the support system 32A, the support system 32B
also includes a pair of roll supporters 33 (not illustrated) and a
plurality of support rollers 34B. The support rollers 34B are
rotatably attached to each of the roll supporters 33. The rear ring
31 is supported by these support rollers 34B. The gantry 28 is
rotated by a rotating system (such as a motor) 49. The rotation
system 49 has a rotating shaft thereof connected to the rotating
shaft of one of the support rollers 34B that support the rear ring
31 through a decelerator 50. An angle detector 51 that detects the
rotating angle of the gantry 28 is connected to the rotating shaft
of one of the support rollers 34A that support the front ring
30.
[0044] A radiation therapy cage (treatment cage) 35 is installed in
the gantry 28. The treatment cage 35 is configured to enable a
medical technician 93 (see FIG. 10), for example, to carry out the
medical treatment on the patient 70 on the treatment stand 62 while
protecting the safety of the patient 70 from the circulating path
of the irradiation system 57 in the circumferential direction of
the gantry 28. That is to say, it is desirable that the treatment
cage 35 provides the scaffolding that enables the medical
technician 93 to carry out the medical treatment and besides the
scaffolding, provides the closed space from the outside.
[0045] The treatment cage 35 includes a movable floor 36, a
fixed-side ring rail 45A, a movable-side ring rail 45B, and a back
panel 46. The fixed-side ring rail 45A is disposed inside the front
ring 30 in accordance with the position of the front ring 30. The
movable-side ring rail 45B is disposed opposite to the front ring
30 and on the rear ring 31 side. The irradiation system 57 is
disposed between the fixed-side ring rail 45A and the movable-side
ring rail 45B. The back panel 46 that accepts the treatment cage 35
in the depth direction is fixed to the movable-side ring rail 45B.
The fixed-side ring rail 45A and the movable-side ring rail 45B
have their opposite surfaces provided with a semi-cylindrical orbit
76 (see FIG. 7). In this embodiment, the semi-cylindrical shape
refers to the shape including the arc-like portion on the upper
side and the horizontal portion on the lower side with the opposite
ends of the arc-like portion smoothly connecting to the opposite
ends of the horizontal portion. The area where the arc-like portion
and the horizontal portion are connected refers to the connected
portion.
[0046] The movable floor 36 includes, as illustrated in FIG. 4, a
number of footboards (footboard members) 38 made of metal (for
example, made of a steel plate), and X-ray transmission plates
(X-ray transmission members) 39 and 40. The movable floor 36 is
disposed between the fixed-side ring rail 45A and the movable-side
ring rail 45B. The movable floor 36 is a surrounding member formed
by a number of footboards 38, the single X-ray transmission plate
39 and the single X-ray transmission plate 40 in a manner that they
are freely bendable. The X-ray transmission plates 39 and 40 are
separately disposed between the adjacent footboards 38 in the
movable floor 36. The footboards 38 do not transmit the X-ray but
the X-ray transmission plates 39 and 40 do. Each footboard 38 is a
long and thin rectangular plate extending in the axis direction of
the gantry 28, and has a width of W.sub.1 in the circumference
direction of the gantry 28 as illustrated in FIG. 5. Each of the
X-ray transmission plates 39 and 40 is a long and thin rectangular
plate extending in the axis direction of the gantry 28, and has a
width of W.sub.2 in the circumference direction of the gantry 28 as
illustrated in FIG. 6. The width W.sub.2 of each of the X-ray
transmission plates 39 and 40 is larger than the width W.sub.1 of
the footboard 38. Each of the X-ray transmission plates 39 and 40
includes a metal plate 94 made of metal such as aluminum alloy and
an X-ray transmission portion (X-ray transmission area) 95 that
transmits the X-ray. The X-ray transmission portion 95 is, for
example, a rectangular graphite plate and has a width of W.sub.3 in
the circumferential direction of the gantry 28. The width W.sub.3
is larger than the width W.sub.1 of the footboard 38 and smaller
than the width W.sub.2 of the X-ray transmission plates 39 and 40.
The movable floor 36 includes footboard groups 74A, 74B, and 74C.
The X-ray transmission plate 39 is disposed between the footboard
group 74A and the footboard group 74C, and the X-ray transmission
plate 40 is disposed between the footboard group 74B and the
footboard group 74C. The X-ray transmission portion 95 is fitted
into an opening, which is provided for the metal plate 94 and has
the same size as the X-ray transmission portion 95, so as to be
unified with the metal plate 94. The X-ray transmission portion 95
is surrounded by the metal plate 94. The X-ray transmission portion
95 can be formed of reinforced glass or plastic instead of
graphite, and is formed of the non-metal material transparent to
the X-ray, such as graphite, reinforced glass, or plastic (the
non-metal material that easily transmits the X-ray). Alternatively,
the X-ray transmission portion 95 may be omitted from the X-ray
transmission plates 39 and 40 and instead, the X-ray transmission
plates 39 and 40 may be formed of the non-metal material
transparent to the X-ray (any of graphite, reinforced glass, and
plastic).
[0047] In the footboard groups 74A, 74B, and 74C, a pair of wheels
is rotatably attached to opposite ends of each footboard 38 in the
longitudinal direction. The X-ray transmission plates 39 and 40 are
provided with a pair of wheels at opposite ends thereof similarly.
In a set of footboard groups 74A, 74B, and 74C, the adjacent
footboards 38 are connected bendably at the opposite ends in the
longitudinal direction of the footboard 38 (the wheels of the
adjacent footboards 38 are connected with a link), and both sides
of each footboard in the width direction is bent inward (see
JP-H-11-47287-A, the paragraph [0018] and FIG. 4). The X-ray
transmission plate 39 is also connected bendably to each of the
adjacent footboard 38 included in the footboard group 74A and the
adjacent footboard 38 included in the footboard group 74C. The
X-ray transmission plate 40 is similarly connected bendably to each
of the adjacent footboard 38 included in the footboard group 74B
and the adjacent footboard 38 included in the footboard group 74C.
An end 44B of each of the footboards 38 and the X-ray transmission
plates 39 and 40 in the axis direction of the gantry 28 runs within
the semi-cylindrical orbit 76 provided for the movable-side ring
rail 45B. An end 44A of each of the footboards 38 and the X-ray
transmission plates 39 and 40 in the axis direction of the gantry
28 runs within the semi-cylindrical orbit 76 provided for the
fixed-side ring rail 45A.
[0048] As illustrated in FIG. 2, the fixed-side ring rail 45A is
supported on a ceiling 92 of the building with a fixed supporter
56, and is further supported on the floor 72 with a fixed supporter
54. The movable-side ring rail 45B is supported by a plurality of
support rollers 48B disposed along a circumferential direction of
the rotary drum 29 on an inner surface of a support ring 55
disposed on an inner surface of the rotary drum 29 of the gantry
28. A ring rail driver 52 rotates the movable-side ring rail 45B in
the direction opposite to the rotation of the gantry 28. The ring
rail driver 52 is connected to one support roller 48A out of the
support rollers 48B through a decelerator 53. The ring rail driver
52 and the decelerator 53 are installed on the inner surface of the
rotary drum 29.
[0049] The irradiation system 57 rotates along with the rotation of
the gantry 28 and driving of the ring rail driver 52 causes the
support roller 48A to rotate the movable-side ring rail 45B in the
opposite direction. If the gantry 28 is rotated in the opposite
direction, the rotation of the support roller 48A by the driving of
the ring rail driver 52 causes the movable-side ring rail 45B to
rotate in the normal direction. Since the movable-side ring rail
45B rotates relative to the gantry 28, the movable-side ring rail
45B seems to stand still when viewed from a treatment room 43. As a
result, even if the gantry 28 is rotated, the treatment cage 35
maintains the semi-cylindrical orbit 76 (the arc-like portion on
the upper side and the horizontal portion on the lower side). That
is to say, the movable floor 36 of the treatment cage 35 constantly
constitutes a horizontal floor portion 79 without depending on the
rotation angle of the gantry 28.
[0050] The movable floor 36 has enough rigidity, and will not
deform even if the medical technician 93 works standing on the
movable floor 36. The movable floor 36 offers a work space around
the treatment stand 62.
[0051] In the footboard group 74C, a cover winding system 42 is
installed between a pair of adjacent footboards 38. Upon the
generation of the opening between the pair of footboards 38, the
cover winding system 42 sends out the cover 41 to close the opening
75 (see FIG. 7). The cover winding system 42 may be configured in
accordance with a known art, such as a winding pipe with the
structure to maintain the tension, for example, roll screen or roll
curtain.
[0052] Description will be made of a connector 68 between the
irradiation system 57 and each end of the movable floor 36 (each of
the footboard groups 74A and 74B) with reference to FIG. 4. The
connector 68 includes a pair of slide members 69A and 69B and a
pair of guide rails 71. The connector 68 is provided for each of a
pair of side surfaces of the irradiation system 57 opposite to each
other in the rotation direction of the gantry 28. The pair of slide
members 69A and 69B is attached to one end of each of the footboard
groups 74A and 74B. A pair of guide rails 71 as the guide members
is installed on each of a pair of side surfaces of the irradiation
system 57 opposite to each other in the rotating direction of the
gantry 28. The slide members 69A and 69B attached to one end of the
footboard group 74A are separately and movably attached to the pair
of guide rails 71 installed on one side surface of the irradiation
system 57. The slide members 69A and 69B attached to one end of the
footboard group 74B are separately and movably attached to the pair
of guide rails 71 installed on the other side surface of the
irradiation system 57. As a result, the one end of each of the
footboard groups 74A and 74B is connected to each of the pair of
side surfaces of the irradiation system 57 by the connector 68 (the
slide members 69A and 69B and a pair of guide rails 71) in a manner
of being slidable in the radial direction of the gantry 28.
[0053] The irradiation system 57 has a shape tapering toward the
center of rotation of the gantry 28. As a result, the pair of side
surfaces of the irradiation system 57 opposite to each other in the
rotating direction of the gantry 28 is inclined relative to the
normal line of the rotation surface of the gantry 28.
[0054] The treatment room 43 is surrounded by the movable floor 36
of the treatment cage 35 within the rotary drum 29. The treatment
room 43 is open on the front ring 30 side and closed by the back
panel 46 on the rear ring 31 side. The irradiation system 57 is
attached to the rotary drum 29 and extends toward the center of the
rotary drum 29, and reaches the treatment room 43 formed more on
the inside than the movable floor 36. The beam path 21 of the GABT
20 connected to the irradiation system 57 extends toward the rear
ring 31 as illustrated in FIG. 2, and communicates with the beam
path 16 of the HEBT 15 in the scramble portion 27 on the outside of
the gantry 28. A center axis 28A of the gantry 28 (see FIG. 1 and
FIG. 2) corresponds to the center of the rotation of the gantry 28
and goes along the center of the entrance of the beam path 21 in
the scramble portion 27.
[0055] The treatment stand 62 includes, as illustrated in FIG. 2, a
bed 63, an X-direction driving mechanism 64, a Y-direction driving
mechanism 66, a vertical driving mechanism 65, and a rotation
driving mechanism 67. These driving mechanisms are disposed outside
the rotary drum 29. The X-direction driving mechanism 64 is
installed in a treatment stand attachment area 73, which is higher
than the floor 72. The X-direction driving mechanism 64 moves the
bed 63 in a direction orthogonal to the rotating axis of the gantry
28. The vertical driving mechanism 65 is installed on the
X-direction driving mechanism 64, the Y-direction driving mechanism
66 is installed on the vertical driving mechanism 65, and the
rotation driving mechanism 67 is installed on the Y-direction
driving mechanism 66. The bed 63 is installed on the rotation
driving mechanism 67 and is supported by these driving mechanisms.
The Y-direction driving mechanism 66 moves the bed 63 in a
direction where the rotation axis of the gantry 28 extends. The
rotation driving mechanism 67 rotates the bed 63 in a horizontal
plane.
[0056] The treatment room 43 is formed by partitioning the space in
the rotary drum 29 of the gantry 28 with the back panel 46, which
serves as a partition wall. The treatment room 43 is set to the
floor level near the rotation center of such a degree that the
rotation radius of the gantry 28 is secured; thus, the treatment
room 43 is set at a height of usually 6 to 8 m relative to the
lowest position of the inner surface of the rotary drum 29.
Therefore, the patient 70 on the bed 63 in the treatment stand 62
exists in the space at that height, and the treatment cage 35
forming the space surrounding the patient 70 therefore needs to be
safe for the patient and the medical technician.
[0057] In order to obtain the image information of the target
volume used to position the target volume before the target volume
is irradiated with a particle beam and to confirm the position of
the target volume during the irradiation with the particle beam,
the particle therapy system 1 includes X-ray sources (X-ray
generators) 71A and 71B and X-ray detection systems (such as flat
panel detectors (FPD)) 72A and 72B. The X-ray detection systems 72A
and 72B are provided for a pair of side surfaces of the irradiation
system 57 opposite to each other in the circulating direction. The
X-ray sources 71A and 71B are disposed at the center axis 97 of the
irradiation system 57 in the axial direction of the gantry 28 (see
FIG. 2). The X-ray detection systems 72A and 72B may be a
semiconductor detector or a scintillator.
[0058] The X-ray source 71A is installed on the outer surface of
the rotary drum 29 of the gantry 28 by a supporter 91 as
illustrated in FIG. 7. A collimator 77A is disposed on the outside
of the rotary drum 29 in front of the X-ray source 71A and is
attached to the supporter 91. The X-ray detection system 72A is
disposed opposite to the X-ray source 71A and is attached to one
side surface of the irradiation system 57 in the circulating
direction as to receive an X-ray 78A emitted from the X-ray source
71A. At the position in the rotary drum 29 opposite to the X-ray
source 71A, a penetration hole (X-ray transmission hole) 96A with
the size to transmit the X-ray emitted from the X-ray source 71A is
formed. In addition, the X-ray source 71A and the penetration hole
96A are disposed opposite to the X-ray transmission plate 40
included in the movable floor 36.
[0059] The X-ray source 71B is installed on the outer surface of
the rotary drum 29 of the gantry 28 by the supporter 91 as
illustrated in FIG. 7. A collimator 77B is disposed on the outside
of the rotary drum 29 in front of the X-ray source 71B and is
attached to the supporter 91. The X-ray detection system 72B is
disposed opposite to the X-ray source 71B and is attached to the
other side surface of the irradiation system 57 in the circulating
direction as to receive an X-ray 78B emitted from the X-ray source
71B. At the position in the rotary drum 29 opposite to the X-ray
source 71B, a penetration hole (X-ray transmission hole) 96B with
the size to transmit the X-ray emitted from the X-ray source 71B is
formed. In addition, the X-ray source 71B and the penetration hole
96B are disposed opposite to the X-ray transmission plate 39
included in the movable floor 36. The X-ray transmission portion 95
of the X-ray transmission plate 39 is disposed opposite to the
X-ray source 71A. The X-ray transmission portion 95 of the X-ray
transmission plate 40 is disposed opposite to the X-ray source
71B.
[0060] Each of the X-ray detection systems 72A and 72B is
substantially configured to have 330 columns.times.330 rows of
X-ray detectors (not illustrated) arranged on each of the planes
thereof facing each of the X-ray transmission plates 39 and 40 (for
example, the square plane with a length of approximately 50 cm on a
side). The X-ray detector has, for example, a square X-ray
incidence surface with a length of approximately 1.5 mm on a side
(see JP-2006-239403-A, the paragraph [0027]).
[0061] The angle between the line connecting an isocenter 98 and
the hole (not illustrated) of the collimator 77A that transmits the
X-ray and the line connecting the isocenter 98 and the hole (not
illustrated) of the collimator 77B that transmits the X-ray is
90.degree. (see FIG. 11). Therefore, the X-ray source 71A and the
X-ray source 71B are disposed displaced by 90.degree. in the
circumferential direction of the gantry 28.
[0062] The function of the X-ray sources 71A and 71B and the X-ray
detection systems 72A and 72B is described based on an example of
positioning the target volume before the target volume is
irradiated with an ion beam. In this embodiment, the target volume
of the patient 70 lying on the bed 63 is positioned by the method
according to JP-2006-239403-A.
[0063] The bed 63 on which the patient 70 lies down is moved by the
driving of the X-direction driving mechanism 64, the Y-direction
driving mechanism 66, the vertical driving mechanism 65, and the
rotation driving mechanism 67; thus, the target volume of the
patient 70 is roughly positioned relative to the irradiation system
57. On this occasion, the rotation angle of the gantry 28 is, for
example, 0.degree. and the irradiation system 57 extends downward.
While the gantry 28 is rotated, the current X-ray computed
tomography is carried out. In this current X-ray computed
tomography, while the gantry 28 is rotated, the X-rays 78A and 78B
are delivered to the target volume of the patient 70 from the X-ray
sources 71A and 71B, respectively. The X-ray 78A emitted from the
X-ray source 71A passes through the collimator 77A and the
penetration hole 96A and further through the X-ray transmission
portion 95 of the X-ray transmission plate 40, and then delivered
to the target volume. The X-ray 78A having transmitted through the
target volume is detected by each X-ray detector of the X-ray
detection system 72A. The X-ray 78B emitted from the X-ray source
71B passes through the collimator 77B and the penetration hole 96B
and further through the X-ray transmission portion 95 of the X-ray
transmission plate 39, and then delivered to the target volume. The
X-ray 78B having transmitted through the target volume is detected
by each X-ray detector of the X-ray detection system 72B. The
irradiation of the target volume with the X-rays 78A and 78B from
the X-ray sources 71A and 71B is carried out while the gantry 28 is
rotated. In this case, the gantry 28 is rotated by, for example,
275.degree. because the X-ray source 71A and the X-ray source 71B
are displaced by 90.degree. in the circumferential direction of the
gantry 28. By rotating the gantry 28 by 275.degree. while the
X-rays are emitted from the X-ray sources 71A and 71B, the X-ray
can be delivered to the target volume of the patient 70 on the bed
63 from 360.degree. around the patient 70.
[0064] Each X-ray detector of the X-ray detection system 72A having
detected the X-ray 78A outputs the X-ray detection signal. The
X-ray detection signal output from each X-ray detector is input to
a signal processor (not illustrated) connected to each X-ray
detector of the X-ray detection system 72A, and each signal
processor accumulates the X-ray detection signals to provide the
X-ray intensity information at every set time interval. Each X-ray
detector of the X-ray detection system 72B having detected the
X-ray 78B also outputs the X-ray detection signal. The X-ray
detection signal output from the X-ray detector is input to a
signal processor (not illustrated) connected to every X-ray
detector of the X-ray detection system 72B, and each signal
processor accumulates the X-ray detection signals to provide the
X-ray intensity information at every set time interval.
[0065] To an image information formation system (tomographic
information formation system) (not illustrated), the X-ray
intensity information for every X-ray detector of the X-ray
detection system 72A, the X-ray intensity information for every
X-ray detector of the X-ray detection system 72B, and the rotation
angle of the gantry 28 measured with the angle detector 51 are
input. Based on the X-ray intensity information and the measured
rotation angles of the gantry 28, the image information formation
system forms the tomographic information (current tomographic
information) including the target volume of the patient 70 (see
JP-2006-239403-A, the paragraph [0037]). The formed current
tomographic information is input to a positioning data generation
system (not illustrated). To the positioning data generation
system, three-dimensional tomographic information (reference
tomographic information) obtained by the X-ray computed tomography
(reference X-ray computed tomography) prepared in advance has
already been input and stored in the memory (not illustrated).
Based on the current tomographic information and the reference
tomographic information, the positioning data generation system
calculates the amount of movement of the bed 63 in the X direction
and the Y direction, corresponding to the bed positioning data in
the X-Y plane, the rotation angle of the bed 63, and the amount of
movement of the bed 63 in the Z direction, corresponding to the bed
positioning data in the X-Z plane (see JP-2006-239403-A, the
paragraphs [0040]-[0044]).
[0066] A bed controller (not illustrated) controls the
corresponding driving mechanism for the treatment stand 62 on the
basis of the input amount of movement of the bed 63 in the X
direction, Y direction, and Z direction and the rotation angle of
the bed 63, thereby moving the bed 63 (see JP-2006-239403-A, the
paragraph [0045]). In this manner, the target volume of the patient
70 on the bed 63 is moved to the position coinciding with the
isocenter 98 located at the intersection between the center axis 97
of the irradiation system 57 and the center axis 28A of the gantry
28, and thus the positioning of the target volume is completed.
After the positioning of the target volume is completed, the target
volume is irradiated with the particle beam in the particle therapy
system 1 to treat the target volume with the particle beam.
[0067] Description is made of the summary of the irradiation of the
target volume of the patient 70 with the particle beam, such as a
proton beam (or carbon beam). The gantry 28 can be rotated by
360.degree. around the patient 70 on the bed 63. Before the target
volume is irradiated with the proton beam (hereinafter simply
referred to as ion beam), the rotation system 49 is driven to
rotate the gantry 28 so that the center axis 97 of the irradiation
system 57 coincides with the irradiation direction of the ion beam
according to the treatment plan. The gantry 28 is rotated at a
speed of 1 min.sup.-1. Whether the center axis 97 of the
irradiation system 57 has coincided with the irradiation direction
of the ion beam is checked based on the rotation angle of the
gantry 28 measured with the angle detector 51.
[0068] In order to turn the irradiation system 57 to the
irradiation direction of the ion beam by rotating the gantry 28,
the movable-side ring rail 45B is rotated in the direction opposite
to the rotation of the gantry 28 by the driving of the ring rail
driver 52. This makes the movable-side ring rail 45B look like it
stands still. Therefore, as the irradiation system 57 is turned by
the rotation of the gantry 28, the movable floor 36 with its
opposite ends attached movably to a pair of guide rails 71 on a
pair of opposite side surfaces of the irradiation system 57 with
the slide members 69A and 69B moves along the semi-cylindrical
orbit 76.
[0069] The gantry 28 having rotated to the set rotation angle is
stopped. Then, the ion (for example, proton) generated in the ion
source is incident into the linear accelerator 14 and then
accelerated therein. The ion beam emitted from the linear
accelerator 14 is incident into the circular beam duct 4 of the
synchrotron accelerator 3 through the injector 5. While circulating
in the beam duct 4, the ion beam is accelerated until having the
set energy (for example, 200 MeV) required to reach the deepest
layer among a plurality of layers of the target volume in the ion
beam irradiation direction. The energy of the ion beam used to
treat the target volume is usually in the range of 100 to 200 MeV,
and is set in accordance with the depth of the target volume from
the surface of the body.
[0070] With the scanning magnets 58 and 59, the irradiation point
of the ion beam within the layer is set. The opening/closing switch
12 is closed and the radiofrequency voltage from the radiofrequency
power source 11 is applied from the extraction radiofrequency
electrode 10 to the ion beam circulating in the beam duct 4. As a
result, the circulating ion beam is emitted from the synchrotron
accelerator 3 to the beam path 16 through the septum magnet 13. The
emitted ion beam reaches the irradiation system 57 through the beam
paths 16 and 21. The ion beam having reached to the inside of the
irradiation system 57 is delivered to the irradiation point of the
ion beam of the target volume in the layer, which has been set by
the scanning magnets 58 and 59.
[0071] While the target volume is irradiated with the ion beam in
the state that the center axis 97 of the irradiation system 57 is
aligned in a predetermined irradiation direction of the ion beam,
the X-ray 78A emitted from the X-ray source 71A and the X-ray 78B
emitted from the X-ray source 71B are delivered to the target
volume of the patient 70 on the bed 63. The X-ray 78A having
transmitted through the patient 70 is detected by each X-ray
detector of the X-ray detection system 72A, and the X-ray 78B
having transmitted through the patient 70 is detected by each X-ray
detector of the X-ray detection system 72B.
[0072] In a manner similar to the aforementioned positioning of the
target volume, the signal processor connected to each X-ray
detector of the X-ray detection system 72A obtains the X-ray
intensity information on the basis of the X-ray detection signal
from the X-ray detector. The image information formation system
forms the primary two-dimensional image information of the target
volume in the plane orthogonal to the radiation direction of the
X-ray 78A from the X-ray source 71A on the basis of the X-ray
intensity information obtained with each signal processor and the
measured rotation angle of the gantry 28. The plane orthogonal to
the radiation direction of the X-ray 78A from the X-ray source 71A
corresponds to the plane orthogonal to the direction to the center
axis 28A of the gantry 28 at an angle obtained by adding
135.degree. to the measured rotation angle of the gantry 28 (the
angle of center axis 97 of the irradiation system 57).
[0073] In a manner similar to the aforementioned formation of the
primary two-dimensional image information, the image information
formation system forms the secondary two-dimensional image
information of the target volume in the plane orthogonal to the
radiation direction of the X-ray 78B from the X-ray source 71B on
the basis of the X-ray intensity information obtained with each
signal processor connected to each X-ray detector of the X-ray
detection system 72B and the measured rotation angle of the gantry
28. The plane orthogonal to the radiation direction of the X-ray
78B from the X-ray source 71B corresponds to the plane orthogonal
to the direction to the center axis 28A of the gantry 28 at an
angle obtained by adding 225.degree. to the measured rotation angle
of the gantry 28 (the angle of the center axis 97 of the
irradiation system 57).
[0074] Based on the primary two-dimensional image information and
the secondary two-dimensional image information, the size and shape
of the target volume can be known in the irradiation with the ion
beam. In addition, based on how the size and shape of the target
volume have changed since the start of the irradiation of the
target volume with the ion beam, the effect of the treatment by the
irradiation with the ion beam can be known.
[0075] Moreover, the primary two-dimensional image information and
the secondary two-dimensional image information formed by the image
information formation system are input to the positioning data
generation system, and the positioning data generation system
calculates the amount of displacement of the target volume
irradiated with the ion beam from the reference tomographic
information on the basis of the reference tomographic information,
the primary two-dimensional image information and the secondary
two-dimensional image information. Based on the calculated amount
of displacement, the position of the target volume currently
irradiated with the ion beam can be known.
[0076] Description is hereinafter made of the operation of the
connector 68 including the slide members 69A and 69B and the pair
of guide rails 71, which connects between the irradiation system 57
and each of the footboard groups 74A and 74B.
[0077] FIG. 7 illustrates the sectional shape of the movable floor
36 of the treatment cage 35 when the irradiation system 57 is right
above the bed 63. In the state illustrated in FIG. 7, the rotation
angle of the gantry 28 is 0.degree.. The slide members 69A and 69B
attached movably to the pair of guide rails 71 provided for each of
the pair of side surfaces of the irradiation system 57 opposite to
each other in the rotating direction of the gantry 28 and attached
to one end of each of the footboards 74A and 74B are in the
farthest position from the center axis 28A of the gantry 28 in the
radial direction of the gantry 28.
[0078] Between the pair of footboards 38 in the footboard group
74C, the cover winding system 42 is installed. Synchronizing with
the generation of the opening 75 between the pair of footboards 38,
the cover winding system 42 sends out the cover 41 so as to close
the opening 75 (see FIG. 7). This opening 75 exists right below the
bed 63 (at the position where the rotation angle of the gantry 28
is 180.degree.). Note that the opening 75 is closed by the cover 41
but this is not illustrated in FIG. 7 for the convenience of
description. Neither FIG. 8 nor FIG. 9 illustrates the cover
41.
[0079] Here, the concept of the inner wall length defined in this
embodiment is described. The irradiation system 57 circulates
around the rotation axis of the gantry 28 as the gantry 28 rotates.
Meanwhile, the semi-cylindrical orbit 76 which is provided for each
of the fixed-side ring rail 45A and the movable-side ring rail 45B
of the treatment cage 35 and which guides the movable floor 36
stands still. Needless to say, the total length of each
semi-cylindrical orbit 76 is constant (unchanged) in the treatment
cage 35. Along the length of the semi-cylindrical orbit 76, which
is the length excluding the length corresponding to the irradiation
system 57 (the length of the irradiation system 57 between the
slide members 69A attached movably to the guide rails 71 on the
pair of side surfaces of the irradiation system 57 opposite to each
other in the rotating direction of the gantry 28) from the entire
length of the semi-cylindrical orbit 76, the arc-like portion and
the horizontal portion are formed. Of the semi-cylindrical orbit
76, the length of the arc-like portion and the horizontal portion
is defined as the inner wall length. That is to say, the inner wall
length corresponds to the difference between the entire length of
the semi-cylindrical orbit 76 and the length corresponding to the
irradiation system 57. On the other hand, the inner wall length
substantially corresponds to the total of the lengths of the
footboard groups 74A, 74B, and 74C, the widths of the X-ray
transmission plates 39 and 40, and the length of the opening
75.
[0080] While the irradiation system 57 is right above the bed 63,
each of the X-ray transmission plates 39 and 40 exists near the
connecting portion of the semi-cylindrical orbit 76.
[0081] If the orbit for guiding the movable floor 36, which is
provided for each of the fixed-side ring rail 45A and the
movable-side ring rail 45B of the treatment cage, is a circular
orbit, the inner wall length is constant not depending on the
rotation angle of the gantry 28. However, since the orbit 76
provided for each of the fixed-side ring rail 45A and the
movable-side ring rail 45B is semi-cylindrical, the inner wall
length is different depending on the rotation angle of the gantry
28. That is to say, since the length corresponding to the
irradiation system 57 is different depending on the rotation angle
of the gantry 28, the inner wall length is different depending on
the rotation angle.
[0082] If the irradiation system 57 is present at the arc-like
portion of the semi-cylindrical orbit 76 (if the gantry 28 is
rotated by the angle ranging from 0.degree. to 90.degree.), the
length corresponding to the irradiation system 57 is constant and
the inner wall length is constant. As a part of the irradiation
system 57 is moved to the connecting portion of the
semi-cylindrical orbit 76 (the rotation angle of the gantry 28
ranges from 90.degree. to 120.degree.) and then to the horizontal
portion (the rotation angle of the gantry 28 ranges from
120.degree. to 180.degree.), the length corresponding to the
irradiation system 57 is changed and the inner wall length is
changed.
[0083] For example, when the rotation angle of the gantry 28 is
180.degree. and the irradiation system 57 is in the horizontal
portion (see FIG. 9), the slide members 69A and 69B attached
movably to the pair of guide rails 71 disposed on each of the pair
of side surfaces of the irradiation system 57 opposite to each
other in the rotating direction of the gantry 28 and attached to
one end of each of the footboard groups 74A and 74B are both in the
closest position to the center axis 28A of the gantry 28 in the
radial direction of the gantry 28. Here, the length of the
irradiation system 57 (the length corresponding to the irradiation
system 57) between the slide member 69A attached to one end of the
footboard group 74A and the slide member 69A attached to one end of
the footboard group 74B is shorter than the length of the
irradiation system 57 between the slide member 69A attached to one
end of the footboard group 74A and the slide member 69A attached to
one end of the footboard group 74B in the state that the
irradiation system 57 is in the arc-like portion with the gantry 28
having a rotation angle of 0.degree. (see FIG. 7).
[0084] When the movable floor 36 is moved along the
semi-cylindrical orbit 76 in accordance with the rotation angle of
the gantry 28, the slide members 69A and 69B separately attached
movably to the pair of guide rails 71 disposed on the pair of side
surfaces of the irradiation system 57 opposite to each other in the
rotating direction of the gantry 28 are moved along with the
movement of the movable floor 36, i.e., along the guide rail 71 in
the radial direction of the gantry 28 as the irradiation system 57
turns.
[0085] While the irradiation system 57 is in the arc-like portion
of the semi-cylindrical orbit 76 (for example, the rotation angle
of the gantry 28 ranges from 0.degree. to 90.degree.), the pair of
slide members 69A and 69B is in the farthest position from the
center axis 28A of the gantry 28 in the radial direction of the
gantry 28. As a part of the irradiation system 57 is moved to the
connecting portion of the semi-cylindrical orbit 76 (the rotation
angle of the gantry 28 ranges 90.degree. to 120.degree.) and then
to the horizontal portion of the orbit 76 (the rotation angle of
the gantry 28 ranges from 120.degree. to 180.degree.), the slide
members 69A and 69B attached to one end of the footboard group 74B
move closer to the center axis 28A of the gantry 28 along the pair
of guide rail 71 disposed on one side surface on the
turning-direction side of the irradiation system 57 as the
irradiation system 57 turns (FIG. 8). While the entire irradiation
system 57 is in the horizontal portion of the semi-cylindrical
orbit 76 (the rotation angle of the gantry 28 ranges from
150.degree. to 180.degree.), the slide members 69A and 69B attached
to one end of the footboard group 74A move closer to the center
axis 28A of the gantry 28 along the pair of guide rail 71 disposed
on the other side surface opposite to the turning-direction side of
the irradiation system 57 as the irradiation system 57 turns (FIG.
9). When the irradiation system 57 approaches to the area right
below the bed 63 (the rotation angle of the gantry 28 is
180.degree.), the slide members 69A and 69B move closer to the
guide rails 71 on both side surfaces of the irradiation system 57
as the irradiation system 57 turns.
[0086] That is to say, the change in inner wall length depending on
the rotation angle of the gantry 28 is synchronized with the change
in length of the opening 75 and the movement of the slide members
69A and 69B along the guide rail 71. Other specific examples than
the example illustrated in FIG. 7 are described with reference to
FIG. 8 and FIG. 9.
[0087] FIG. 8 illustrates the state of the movable floor 36 of the
treatment cage 35 when the irradiation system 57 is at the position
where the rotation angle of the gantry 28 is 135.degree.. A part of
the irradiation system 57 is in the horizontal portion of the
semi-cylindrical orbit 76. In this state, the slide members 69A and
69B attached to one end of the footboard group 74B move closer to
the center axis 28A of the gantry 28 in the radial direction of the
gantry 28, and the slide members 69A and 69B attached to one end of
the footboard group 74A is in the farthest position from the center
axis 28A of the gantry 28 in the radial direction of the gantry 28.
At this time, the inner wall length is the shortest and the length
of the opening 75 is also the shortest. The length of the portion
of the movable floor 36 (this portion is hereinafter referred to as
a first movable floor portion) from the slide members 69A and 69B
to the opening 75 on the footboard group 74A side and the length of
the portion of the movable floor 36 (this portion is hereinafter
referred to as a second movable floor portion) from the slide
members 69A and 69B to the opening 75 on the footboard group 74B
side are set so that the first movable floor portion and the second
movable floor portion do not interfere with each other when the
inner wall length is the shortest, i.e., so that the opening 75 has
a length of 0 or more. The first movable floor portion includes the
X-ray transmission plate 39 and the second movable floor portion
includes the X-ray transmission plate 40.
[0088] FIG. 9 illustrates the state of the movable floor 36 of the
treatment cage 35 when the irradiation system 57 is at the position
where the rotation angle of the gantry 28 is 180.degree.. The
entire irradiation system 57 is present in the horizontal portion
of the semi-cylindrical orbit 76. The slide members 69A and 69B
attached to one end of each of the footboard groups 74A and 74B
move toward the center of the pair of guide rails 71 provided on
the circulating-direction side and opposite to the
circulating-direction side of the irradiation system 57 as the
movable floor 36 moves along the semi-cylindrical orbit 76. On this
occasion, the length of the opening 75 is the maximum. The opening
75 is right above the bed 63 (at the position corresponding to a
rotation angle of 0.degree.).
[0089] Next, description is made of the safe approach of the
medical technician 93 to the patient 70 at every rotation angle of
the gantry 28, focusing on the change in position and length of the
opening 75 depending on the rotation angle of the gantry 28. While
the irradiation system 57 is at the position where the gantry 28
has a rotation angle of 0.degree., the opening 75 is at the
position corresponding to a rotation angle of 180.degree., i.e.,
right below the bed 63 (see FIG. 7). Therefore, the opening 75 does
not lead to a safety problem. While the irradiation system 57 is
present at the position where the rotation angle of the gantry 28
ranges from 0.degree. to 60.degree., the opening 75 is generated in
the horizontal floor portion 79 of the movable floor 36 and the
horizontal floor portion 79 is formed by the footboard group 74C.
However, the structure with the inclination (tapered shape) of the
irradiation system 57 as described below provides the effect that
enables the opening 75 to maintain the very small length; thus, the
opening 75 does not lead to the safety problem. In addition, the
opening 75 is closed by the cover 41, thereby preventing the
medical technician 93 and the patient 70 from feeling anxiety.
[0090] While the irradiation system 57 is present at the position
where the rotation angle of the gantry 28 ranges from 60.degree. to
180.degree., the opening 75 is not generated in the horizontal
floor portion 79 of the movable floor 36. Thus, the opening 75 does
not lead to the safety problem. In particular, when the irradiation
system 57 is at the position where the rotation angle of the gantry
28 is 135.degree., the length of the opening 75 is the shortest
(substantially 0 in this embodiment) (see FIG. 8). When the
irradiation system 57 is at the position where the rotation angle
of the gantry 28 is 180.degree., the length of the opening 75 is
the maximum but the opening 75 is at the position corresponding to
a rotation angle of 0.degree., i.e., right above the bed 63 (see
FIG. 9), in which case the safety problem is not concerned. In this
regard, the opening 75 is closed by the cover 41, so that people do
not feel anxiety.
[0091] In this manner, in this embodiment, the medical technician
93 can stand on the horizontal floor portion 79 of the movable
floor 36 and approach the patient 70 safely without depending on
the rotating angle of the gantry 28.
[0092] To help the understanding of the operation, the numerals of
the rotation angles of the gantry 28 are illustrated as examples
and may vary depending on the size of the semi-cylindrical orbit 76
and the size of the irradiation system 57. In addition, the
operation when the irradiation system 57 is present at the position
where the rotation angle of the gantry 28 ranges from 0.degree. to
180.degree. has been described, and the operation when the
irradiation system 57 is present at the position where the rotation
angle of the gantry 28 ranges from 180.degree. to 360.degree. is
omitted because the treatment cage 35 is horizontally
symmetric.
[0093] In this embodiment, the orbit 76 including the arc-like
portion and the horizontal portion connected to opposite ends of
the arc-like portion is provided for each of the fixed-side ring
rail 45A and the movable-side ring rail 45B. Thus, the movable
floor 36 moving along this orbit 76 forms the horizontal floor
portion 79 in the horizontal portion of the orbit 76. The medical
technician 93 can stand on the horizontal floor portion 79 and
easily access (for example, perform medical act on) the patient 70
on the bed 63 inserted into the treatment room 43.
[0094] The X-ray sources 71A and 71B are attached to the rotary
drum 29 of the gantry 28, and the X-ray detection systems 72A and
72B are attached to the irradiation system 57 opposite to the X-ray
sources 71A and 71B, respectively. This configuration eliminates
the necessity of moving the X-ray sources 71A and 71B and the X-ray
detection systems 72A and 72B in the axial direction of the gantry
28 in the X-raying of the target volume in order to position the
target volume or the like. Thus, the time required to start the
X-raying can be shortened. This can improve the treatment
throughput. In this X-raying, the X-rays 78A and 78B emitted from
the X-ray sources 71A and 71B can be delivered to the patient 70 on
the bed 63 though the X-ray transmission plates 40 and 39 provided
for the movable floor 36, respectively.
[0095] In the particle therapy system according to
JP-2006-239403-A, however, the irradiation system is provided with
the X-ray source (X-ray tube); therefore, the position of the
target volume cannot be checked while the target volume is
irradiated with the ion beam. In the particle therapy system 1
according to this embodiment, on the other hand, the X-ray sources
71A and 71B are attached to the gantry 28. This configuration
enables to irradiate the target volume in two different directions
with the X-rays 78A and 78B emitted from the X-ray sources 71A and
71B, respectively, while the target volume is irradiated with the
ion beam. In addition, the X-rays 78A and 78B having transmitted
through the target volume can be detected by the X-ray detection
systems 72A and 72B. With the X-ray detection signals output from
the X-ray detectors of the X-ray detection systems 72A and 72B, the
tomographic information of the target volume of the patient 70 on
the bed 63 who is irradiated with the ion beam from the irradiation
system 57 can be formed. With the use of this tomographic
information, the position of the target volume irradiated with the
ion beam can be known. Since the X-rays 78A and 78B are delivered
to the target volume from the two different directions, the
position of the target volume irradiated with the ion beam can be
known with high accuracy. In addition, by using the tomographic
information, the change in size of the target volume irradiated
with the ion beam can be known, and the treatment effect by the
irradiation with the ion beam can be known.
[0096] The X-ray sources 71A and 71B and the collimators 77A and
77B may be attached to the inner surface of the rotary drum 29 and
disposed outside the movable floor 36. The thusly arranged X-ray
sources 71A and 71B and the like can provide the positioning data
of the target volume, and makes it possible to know the position of
the target volume irradiated with the ion beam and the change in
size of the target volume irradiated with the ion beam.
[0097] In this embodiment, the X-ray sources 71A and 71B are
attached to the outer surface of the rotary drum 29 of the gantry
28. This configuration can reduce the space formed between the
movable floor 36 and the inner surface of the rotary drum 29 and
reduce the diameter of the gantry 28, as compared to the case in
which the X-ray sources 71A and 71B are attached to the inner
surface of the rotary drum 29. Thus, the gantry 28 can be reduced
in size.
[0098] The X-ray 78A emitted from the X-ray source 71A attached to
the outer surface of the rotary drum 29 is delivered to the target
volume of the patient 70 through the penetration hole 96A provided
for the rotary drum 29 and through the X-ray transmission portion
95 of the X-ray transmission plate 40. Thus, the emitted X-ray 78A
can be delivered to the patient 70 without being blocked. This can
provide the clear image of and near the target volume with the use
of the compact X-ray source 71A. The X-ray 78B emitted from the
X-ray source 71B attached to the outer surface of the rotary drum
29 is delivered to the target volume of the patient 70 through the
penetration hole 96B provided for the rotary drum 29 and through
the X-ray transmission portion 95 of the X-ray transmission plate
39. Thus, the X-ray 78B emitted from the X-ray source 71B also
provides the similar effect.
[0099] It is necessary to make the center axis 97 of the
irradiation system 57 coincide with the irradiation direction of
the ion beam formed by the treatment plan. The particle therapy
system 1 is configured to deliver the ion beam to the target volume
from around in the range of substantially 0.degree. to 360.degree..
The present inventors have found that, when the target volume is
irradiated with the X-ray from around the target volume, the
positions on the X-ray transmission plates 40 and 39 where the
X-rays 78A and 78B emitted from the X-ray sources 71A and 71B
transmit vary depending on the rotation angle of the gantry 28. How
the transmission position changes is described with reference to
FIG. 11, FIG. 12, and FIG. 13.
[0100] FIG. 11 illustrates the position of each X-ray transmission
plate and the position of the X-ray transmission on the X-ray
transmission plate in the treatment cage when the rotation angle of
the gantry is 0.degree., FIG. 12 illustrates those positions when
the rotation angle of the gantry is 90.degree., and FIG. 13
illustrates those positions when the rotation angle of the gantry
is 180.degree.. As the movable floor 36 is moved along the orbit 76
along with the rotation of the gantry 28, the X-ray transmission
plates 39 and 40 of the movable floor 36 are also moved along the
orbit 76 smoothly. Along with this, the positions of the X-ray
transmission plates 39 and 40 in the orbit 76 change according to
the rotation angle of the gantry 28. In addition, the positions on
the X-ray transmission plates 39 and 40 where the X-rays 78A and
78B transmit also vary in the circumferential direction of the
gantry 28 in accordance with the rotation angle of the gantry 28 as
illustrated in FIG. 11, FIG. 12, and FIG. 13. Since the rotation of
the gantry 28 thusly changes the transmission position of the X-ray
on each of the X-ray transmission plates 39 and 40, the width
W.sub.3 of the X-ray transmission portion 95 in the circumferential
direction of the gantry 28 needs to be larger than the width
W.sub.1 of the footboard 38. As the horizontal portion of the
semi-cylindrical orbit 76 has a width of W.sub.H, the horizontal
floor portion 79 of the movable floor 36 formed by this horizontal
portion also has a width of W.sub.H. The horizontal floor portion
79 needs to be formed in order to enable the medical technician 93
to approach the patient on the bed 63 to conduct the treatment in
the treatment room 43 safely. For these reasons, the X-ray
transmission plates 39 and 40 need to have the width W.sub.2 that
is less than or equal to W.sub.H-W.sub.1 (.gtoreq.W.sub.2).
[0101] The treatment cage according to JP-2011-156263-A
(hereinafter referred to as the conventional treatment cage,
simply) includes a pair of drivers attached to the irradiation
system at the opposite ends of the movable floor, and a controller
that controls these drivers on the basis of the rotation angle of
the gantry. Upon the generation of the opening between the
irradiation system and one end of the movable floor as the movable
floor moves along the semi-cylindrical orbit with the rotation of
the gantry, the controller controls the driver in accordance with
the rotation angle of the gantry, causing the driver to attract the
end of the movable floor toward the irradiation system (see
JP-2011-156263-A, paragraph [0056] and FIG. 6). This prevents the
space from being formed between the movable floor and the
irradiation system in the horizontal floor portion, enabling the
medical technician to approach the patient 70 on the bed 63
safely.
[0102] However, the conventional treatment cage requires the
drivers, the controller, and the driving source for driving those,
which has increased the number of components and complicated the
system. Complication of the system leads to the higher
manufacturing cost. Moreover, the complicated system will easily
result in troubles and therefore require the careful maintenance.
As thus described, the treatment cage according to the conventional
technique needs to be improved from the economical and maintenance
point of view.
[0103] This embodiment employs the connector 68 including the slide
members 69A and 69B and the pair of guide rails 71. With this
connector 68, the opposite ends of the movable floor 36 are
connected to the pair of side surfaces of the irradiation system 57
opposite to each other in the rotating direction of the gantry 28.
This connection enables the treatment cage 35 in this embodiment to
omit the drivers, the controller, and the driving sources for
those, which have been required in the conventional radiation
treatment cage (hereinafter referred to as the conventional
treatment cage), and therefore to be simpler than the conventional
treatment cage. The simplified treatment cage 35 according to this
embodiment experiences fewer troubles and requires less maintenance
work.
[0104] In this embodiment, with the rotation of the gantry 28, the
slide members 69A and 69B attached to the opposite ends of the
movable floor 36 slide along the pair of guide rails 71 provided
for the pair of side surfaces of the irradiation system 57 opposite
to each other in the rotating direction of the gantry 28, and move
in the radial direction of the gantry 28. This enables the medical
technician 93 to approach the patient 70 on the bed 63 safely
without depending on the rotation angle of the gantry 28. That is
to say, in this embodiment, it is not necessary to control the
drivers to attract the end of the movable floor toward the
irradiation system or set it away from the irradiation system,
which is different from the conventional treatment cage. Thus, in
this embodiment, the time required for one treatment can be
shortened and the workability can be improved.
[0105] In the conventional treatment cage, the driver is provided
for each of the front surface and the rear surface of the
irradiation system, and the space where the drivers are installed
has restricted the work space. In this embodiment, the connector 68
with the simple structure including the slide members 69A and 69B
and the pair of guide rails 71 is provided for the side surface of
the irradiation system 57. This configuration can provide the
enough work space as compared to the conventional treatment cage.
As a result, the workability can be improved in this
embodiment.
[0106] In the conventional treatment cage, the operation sound
caused by the driving possibly makes the patient feel anxiety. In
this embodiment, however, the slide members 69A and 69B move along
the pair of guide rails 71 synchronizing with the rotation of the
gantry 28; thus, such driving sound is not generated. Thus, the
patient does not feel anxiety.
[0107] In addition, when the irradiation system is present
particularly at the position where the rotation angle of the gantry
28 is 150.degree. in the conventional treatment cage (see
JP-2011-156263-A, FIG. 6), the opening is generated between the
irradiation system and the end of the movable floor near the bed
63. In this point, the drivers are controlled to pull the end of
the movable floor, thereby closing the opening in the horizontal
floor portion. Normally, before the opening is closed, the
interlocking function is activated to prohibit the entry of the
medical technician into the treatment cage and the safety of the
medical technician is thus secured. However, for some reasons, the
medical technician possibly enters the treatment cage and stands on
the horizontal floor portion of the movable floor, and the higher
safety countermeasure has been demanded. Moreover, the patient on
the bed might see out of the treatment cage through the opening
until the opening is closed. In this case, the patient may fear of
the medical treatment on such a high place.
[0108] In this embodiment, the connector 68 connects the side
surfaces of the irradiation system 57 and the opposite ends of the
movable floor 36. This configuration will not allow the opening to
be generated between the irradiation system 57 and the end of the
movable floor 36 near the bed 63 when, for example, the irradiation
system 57 is at the position where the rotation angle of the gantry
28 is 150.degree. (see FIG. 10). This can further enhance the
safety.
[0109] In this embodiment, the X-ray transmission plates 39 and 40
can have smaller width in the circumferential direction of the
gantry 28. If the opposite ends of the movable floor are attached
to the pair of opposite side surfaces of the irradiation system by
the drivers as illustrated in FIG. 6 of JP-2011-156263-A, it is
necessary to attract or send out the ends of the movable floor with
the drivers so as to close the opening generated between the side
surface of the irradiation system and the end of the movable floor
in the horizontal floor portion. Thus, the amount of movement of
the movable floor in the circumferential direction in order to
close the opening is increased. In this embodiment, as described
above, the opposite ends of the movable floor 36 are attached to
the side surfaces of the irradiation system 57 by the slide members
69A and 69B and the pair of guide rails 71. This configuration
eliminates the necessity of moving the movable floor in the
circumferential direction by the driver and enables the X-ray
transmission plates 39 and 40 to have smaller width in the
circumferential direction of the gantry 28.
[0110] In this embodiment, the pair of side surfaces of the
irradiation system 57 opposite to each other in the rotating
direction of the gantry 28 is inclined toward the end of the
irradiation system 57 so that the irradiation system 57 has the
tapered structure. Description is made of the effect from the
irradiation system 57 with such a tapered structure with a
comparison to a treatment cage according to a second embodiment to
be described below (FIG. 14 and FIG. 15).
[0111] In the second embodiment as described below, a pair of side
surface of an irradiation system 57A attached to the gantry 28
opposite to each other in the rotating direction of the gantry 28
is parallel to the normal line of the rotation surface of the
gantry 28. That is to say, this irradiation system 57A (illustrated
with a dashed line in FIG. 10) has a box-like shape.
[0112] When the irradiation system 57A is at the position where the
rotation angle of the gantry 28 is 135.degree., the length of the
opening 75 is the shortest (see FIG. 15) and the length of each of
the first movable floor portion and the second movable floor
portion is set so that the first movable floor portion and the
second movable floor portion do not interfere with each other at
the shortest inner wall length, i.e., so that the length of the
opening 75 is 0 or more.
[0113] FIG. 10 illustrates the comparison between this embodiment
and the second embodiment. Since the irradiation system 57 in this
embodiment is different in shape from the irradiation system 57A in
the second embodiment, the total length of the first movable floor
portion and the second movable floor portion in this embodiment is
longer by the length d than the total length of the first movable
floor portion and the second movable floor portion in the second
embodiment. This is because the width between the slide member 69A
attached to the end of the first movable floor portion and attached
to one side surface of the irradiation system 57 in the rotating
direction of the gantry 28 through the guide rail 71 and the slide
member 69A attached to the end of the second movable floor portion
and attached to the other side surface of the irradiation system 57
in the rotating direction of the gantry 28 through the guide rail
71 is larger than the width of the irradiation system 57A.
[0114] Meanwhile, when the irradiation system 57A is at the
position where the rotation angle of the gantry 28 is 0.degree.,
the opening 75 generated right below the bed 63 is larger in the
second embodiment (see FIG. 14) than the opening 75 in the first
embodiment (see FIG. 7). The opening 75 in the second embodiment is
larger than the opening 75 in the first embodiment because of the
difference d between the total length of the first movable floor
portion and the second movable floor portion in this embodiment and
the total length of the first movable floor portion and the second
movable floor portion in the second embodiment. In other words,
this is because of the difference in shape between the irradiation
system 57 and the irradiation system 57A. While the irradiation
system 57A is at the position where the rotation angle of the
gantry 28 ranges from 0.degree. to 60.degree., the relatively large
opening 75 is formed in the horizontal floor portion 79 and this
may lead to the safety problem as illustrated in FIG. 14.
[0115] In this embodiment, the irradiation system 57 has the
tapered structure where the pair of side surfaces of the
irradiation system 57 opposite to each other in the rotating
direction of the gantry 28 is inclined toward the end of the
irradiation system 57. This configuration causes the slide members
69A and 69B attached to the ends of the movable floor 36 to move in
the radial direction of the gantry 28 on the inclined side surface
of the irradiation system 57. As a result, the change in length in
the range corresponding to the irradiation system 57 included in
the entire length of the semi-cylindrical orbit 76 in the radial
direction of the gantry 28 is suppressed. Thus, the length of the
opening 75 generated in the horizontal floor portion 79 is
maintained to be very small, which enhances the safety further.
[0116] The irradiation system 57A employed in the second embodiment
has the box-like shape, and particularly, when the irradiation
system 57A is at the position where the rotation angle of the
gantry 28 is 150.degree., the irradiation system 57A interrupts the
medical technician 93 approaching the patient 70 on the bed 63 in
the treatment room 43, which leads to a problem in workability.
[0117] The irradiation system 57 used in this embodiment has the
tapered shape, and in particular, when the irradiation system 57 is
at the position where the rotation angle of the gantry 28 is
150.degree., the medical technician 93 can approach the patient 70
more by the length d (see FIG. 10) as compared to the embodiment,
and thus the workability can be improved.
[0118] In this embodiment, the treatment cage 35 includes the cover
41 and the cover winding system 42; thus, the following effects can
be obtained. As described above, while the irradiation system 57 is
at the position where the rotation angle of the gantry 28 ranges
from 0.degree. to 60.degree., the microscopic opening 75 is
generated in the horizontal floor portion 79 as illustrated in FIG.
7. The length of the opening 75 is maintained to be very small and
the safety problem does not occur. For the additional safety, the
cover winding system 42 may operate to close the opening 75 with
the cover 41. While the irradiation system 57 is at the position
where the rotation angle of the gantry 28 ranges from 60.degree. to
180.degree., the opening 75 is not generated in the horizontal
floor portion 79 (see FIG. 8 and FIG. 9); thus the opening 75 does
not lead to the safety problem. For the additional safety, the
opening 75 may be closed with the cover 41. This can eliminate the
anxiety from the operator and the patient.
[0119] In the current X-ray computed tomography for positioning the
target volume before the target volume is irradiated with the ion
beam, in this embodiment, the X-rays emitted from the X-ray sources
71A and 71B are delivered to the target volume of the patient 70
while the gantry 28 is rotated. In this current X-ray CT, however,
the X-ray emitted from one X-ray source, for example the X-ray
source 71A, may be delivered to the target volume while the gantry
28 is rotated. That is to say, the X-ray emitted from the X-ray
source 71A passes through the collimator 77A and the penetration
hole 96A and further through the X-ray transmission portion 95 of
the X-ray transmission plate 40 before being delivered to the
target volume. The X-ray having transmitted through the target
volume is detected by each X-ray detector included in the X-ray
detection system 72A. In this case, the gantry 28 is rotated in the
range of, for example, 365.degree.. Based on the X-ray detection
signals output from the X-ray detectors of the X-ray detection
system 72A, the X-ray intensity information can be obtained. The
image information formation system forms the tomographic
information including the target volume of the patient 70 on the
basis of the X-ray intensity information for each X-ray detector of
the X-ray detection system 72A and each measured rotation angle of
the gantry 28. The positioning data generation system forms the
aforementioned bed positioning data on the basis of the current
tomographic information and the reference tomographic
information.
[0120] In the first embodiment, the X-ray sources 71A and 71B are
circulated around the patient 70 on the bed 63 by rotating the
gantry 28 while the X-rays are emitted from the X-ray sources 71A
and 71B. Thus, the current tomographic information is obtained. In
contrast, in JP-H-1-209077-A, the target volume is positioned
without circulating the X-ray source emitting the X-ray around the
patient 70 on the bed 63. In such positioning of the target volume,
the particle therapy system 1 according to this embodiment can be
employed. For example, the gantry 28 is rotated up to a rotation
angle of 45.degree. so that the X-ray 78A from the X-ray source 71A
travels in the Z-direction and the X-ray 78B from the X-ray source
71B travels in the X-direction.
[0121] As described above, the bed controller controls the driving
mechanisms for the treatment stand 62 to move the patient 70 on the
bed 63 to the predetermined position. In the state that the
rotation angle of the gantry 28 is 45.degree., the X-ray 78A
emitted upward from the X-ray source 71A travels through the
penetration hole 96A and further through the X-ray transmission
portion 95 of the X-ray transmission plate 40 before the X-ray 78A
is delivered to the target volume of the patient 70 on the bed 63
from below. The X-ray 78A having transmitted through the target
volume is detected by each X-ray detector included in the X-ray
detection system 72A.
[0122] The X-ray 78B emitted horizontally from the X-ray source 71B
travels through the penetration hole 96B and further through the
X-ray transmission portion 95 of the X-ray transmission plate 39
before the X-ray 78B is delivered horizontally to the target volume
of the patient 70 on the bed 63. The X-ray 78B having transmitted
through the target volume is detected by each X-ray detector
included in the X-ray detection system 72B.
[0123] With the X-ray detection signals output from the X-ray
detectors included in the X-ray detection system 72A and the X-ray
detection signals output from the X-ray detectors included in the
X-ray detection system 72B, the positioning data generation system
provides the amount of movement of the bed 63 in the X-Y plane, the
rotation angle of the bed 63, and the amount of movement of the bed
63 in the X-Z plane as described in JP-H-1-209077-A. The amounts of
movement of the bed 63 and the rotation angle of the bed 63 are
input to the bed controller, and the bed controller controls the
corresponding driving mechanism for the treatment stand 62, thereby
positioning the bed 63 before the target volume is irradiated with
the ion beam.
[0124] The treatment cage 35 used in the first embodiment includes
the cover 41 and the cover winding system 42. The operation of the
cover winding system 42 closes the opening 75 in the horizontal
floor portion 79 with the cover 41, and eliminates the anxiety from
the patient 70 and the medical technician 93 in the treatment room
43. For this reason, it is preferable to have the cover 41 and the
cover winding system 42. However, since the opening 75 does not
lead to the safety problem as below, the treatment cage 35 does not
necessarily include the cover 41 and the cover winding system 42.
For example, while the irradiation system 57 is present at the
position where the rotation angle of the gantry 28 ranges from
0.degree. to 60.degree., the opening 75 is generated in the
horizontal floor portion 79 (see FIG. 7). As described above, with
the tapered structure of the irradiation system 57, the length of
the opening 75 can be maintained to be very small, so that the
opening 75 does not lead to the safety problem. Moreover, while the
irradiation system 57 is present at the position where the rotation
angle of the gantry 28 ranges from 60.degree. to 180.degree., the
opening 75 is not generated in the horizontal floor portion 79 (see
FIG. 9), so that the opening 75 does not lead to the safety
problem.
[0125] By omitting the cover 41 and the cover winding system 42,
the number of components of the treatment cage can be reduced and
the treatment cage can be simplified further as compared to the
first embodiment.
[0126] In the first embodiment, each of the pair of side surfaces
of the irradiation system 57 opposite to each other in the rotating
direction of the gantry 28 is provided with the guide rail 71;
however, the guide rail 71 may alternatively be provided for each
of the front surface and the rear surface of the irradiation system
57. That is to say, if the guide rail 71 is provided for each of
the front surface and the rear surface of the irradiation system 57
in parallel to the side surface of the irradiation system 57 facing
in the rotating direction of the gantry 28, the slide members 69A
and 69B attached to the end of the movable floor 36 can be
separately moved along the guide rails 71 provided for the front
surface and the rear surface of the irradiation system 57, which is
similar to the first embodiment. For example, when the irradiation
system 57 is present at the position where the rotation angle of
the gantry 28 is 150.degree., the connector 68 connects between the
irradiation system 57 and the end of the movable floor 36. In this
case, the opening 75 is not generated between the end of the
movable floor 36 and the irradiation system 57 in the horizontal
floor portion 79. This can increase the safety like in the first
embodiment (see FIG. 10). Note that the front surface of the
irradiation system 57 corresponds to the side surface of the
irradiation system 57 on the treatment stand 62 side, and the rear
surface of the irradiation system 57 corresponds to the side
surface of the irradiation system 57 on the back panel 46 side.
[0127] This embodiment employs two sets of X-ray sources and X-ray
detection systems: the X-ray source 71A and the X-ray detection
system 72A; and the X-ray source 71B and the X-ray detection system
72B. However, one of these sets may be employed. If one set of
X-ray source and X-ray detection system is used, the movable floor
36 includes one X-ray transmission plate opposite to each of one
set of X-ray source and X-ray detection system. In the case of
using one set of X-ray source and X-ray detection system, the
position of the target volume when the ion beam is delivered cannot
be known; however, since the X-ray can be delivered to the patient
from the X-ray source while the gantry 28 is rotated, the
positioning of the target volume is possible.
[0128] The first embodiment is similarly applicable to a particle
therapy system including a gantry rotating in the range of
180.degree. (a half gantry) instead of the gantry 28 rotating in
the range of 360.degree..
Second Embodiment
[0129] A particle therapy system according to the second embodiment
corresponding to another preferred embodiment of the present
invention is described with reference to FIG. 14 and FIG. 15.
[0130] A particle therapy system 1A according to this embodiment
includes the irradiation system 57A instead of the irradiation
system 57 in the particle therapy system 1 according to the first
embodiment. The irradiation system 57A employed in the particle
therapy system 1A has the box-like shape, which is different from
the irradiation system 57. A pair of side surfaces of the
irradiation system 57A opposite to each other in the rotating
direction of the gantry 28 is parallel to the normal line of the
rotation surface of the gantry 28 (the side surfaces of the
irradiation system 57A are not inclined). The other structure of
the particle therapy system 1A is the same as the particle therapy
system 1 according to the first embodiment.
[0131] The irradiation system 57A has the box-like shape and is not
tapered; thus, the particle therapy system 1A according to this
embodiment does not provide the effect of the particle therapy
system 1 according to the first embodiment: the change in the
length corresponding to the irradiation system 57 included in the
entire length of the semi-cylindrical orbit 76 in the radial
direction of the gantry 28 is suppressed. In the particle therapy
system 1A, however, the connector 68 connects between the opposite
ends of the movable floor 36 and the pair of side surfaces of the
irradiation system 57A opposite to each other in the rotating
direction of the gantry 28, so that the effect from the connector
68 can be obtained. In this embodiment, the effects obtained from
the first embodiment other than the effect that the change in the
length corresponding to the irradiation system 57 included in the
entire length of the semi-cylindrical orbit 76 in the radial
direction of the gantry 28 is suppressed can be achieved.
[0132] In this embodiment, however, the opening 75 (see FIG. 14)
generated in the horizontal floor portion 79 while the irradiation
system 57A is present at the position where the rotation angle of
the gantry 28 is 0.degree. is larger than the opening 75 (see FIG.
7) generated in the horizontal floor portion 79 while the
irradiation system 57 is present at the position where the rotation
angle of the gantry 28 is 0.degree. in the first embodiment; thus,
the second embodiment is inferior to the first embodiment in point
of safety. In order to improve the safety by solving this problem,
the structure of the treatment cage 35 used in the second
embodiment may be changed a little as described below.
[0133] In the second embodiment, for example, the movable floor 36
including the two cover winding systems 42 may be used. In this
case, the movable floor 36 includes, for example, three movable
floor portions: the first movable floor portion (footboard group
74A), the second movable floor portion (footboard group 74B), and a
third movable floor portion (X-ray transmission plate 39, footboard
group 74C, and X-ray transmission plate 40), and further includes
the cover winding system (first cover winding system) 42 disposed
between the first movable floor portion and the third movable floor
portion and the cover winding system (second cover winding system)
42 disposed between the second movable floor portion and the third
movable floor portion. In this case, the movable floor 36 has a
latch structure (not illustrated) that fixes the intermediate third
movable floor portion to the gantry 28 in the rotating
circumferential direction. The other structure is the same as the
particle therapy system 1 in the first embodiment.
[0134] The movable floor 36 includes the first movable floor
portion, the second movable floor portion, and the third movable
floor portion. This configuration does not allow the generation of
the opening 75 in the horizontal floor portion 79 while the
irradiation system 57A is present at the position where the
rotation angle of the gantry 28 is 0.degree., which is similar to
the first embodiment. Thus, the opening 75 of the movable floor 36
does not lead to the safety problem. If the opening 75 generated
between the first movable floor portion and the third movable floor
portion (between the footboard 38 at the end of the first movable
floor portion and the X-ray transmission plate 39 adjacent to this
footboard 38) or the opening 75 generated between the second
movable floor portion and the third movable floor portion (between
the footboard 38 at the end of the second movable floor portion and
the X-ray transmission plate 40 adjacent to this footboard 38)
exists in the horizontal floor portion 79, the first cover winding
system 42 or the second cover winding system 42 is operated to
close the opening 75 in the horizontal floor portion 79 with the
cover 41. This eliminates the anxiety from the medical technician
93 and the patient 70. In the case of putting the cover 41 on the
opening 75 in the horizontal floor portion 79 by the operation of
the first and second cover winding systems 42, the cover 41 is
preferably pulled out from the X-ray transmission plate 39 or 40
side toward the footboard 38 of the first movable floor portion or
the second movable floor portion so that the pulled cover 41 is not
overlapped on the X-ray transmission plate 39 or 40.
Third Embodiment
[0135] Description is hereinafter made of a particle therapy system
according to a third embodiment corresponding to another preferred
embodiment of the present invention with reference to FIG. 16.
[0136] The particle therapy system 1 according to the first example
employs the ion beam generator 2 including the synchrotron
accelerator 3 but a particle therapy system 1B according to this
embodiment employs an ion beam generator 2A including a cyclotron
accelerator 83.
[0137] The particle therapy system 1B includes, as illustrated in
FIG. 16, the ion beam generator 2A, the HEBT 15, the GABT 20, the
gantry 28, and the irradiation system 57. The structure of the
particle therapy system 1B is the same as that of the particle
therapy system 1 except the ion beam generator 2A. Here, the ion
beam generator 2A, in which the particle therapy system 1B is
different from the particle therapy system 1, is mainly
described.
[0138] The ion beam generator 2A includes an ion source 82 and the
cyclotron accelerator 83. The cyclotron accelerator 83 includes a
circular vacuum vessel 84, bending magnets 88A and 88B, a
radiofrequency accelerator 87, and an extraction septum magnet 89.
A vacuum duct 85 has one end connected to the ion source 82 and the
other end extending to the center of the vacuum vessel 84 and
connecting to the vacuum vessel 84. An injection electrode 86
curving on the horizontal plane is disposed in the vacuum vessel 84
near the open end of the vacuum duct 85. The bending magnets 88A
and 88B have the semi-circular shape and are disposed with their
linear portions facing each other, and cover the upper and lower
surfaces of the vacuum vessel 84.
[0139] The septum magnet 89 provided for the ion beam exit of the
vacuum vessel 84 is connected to the beam path 16 of the HEBT 15. A
degrader 90 with a plurality of metal plates is attached to the
beam path 16 between the septum magnet 89 and a quadrupole magnet
18. The degrader 90 has a function of adjusting the energy of the
ion beam emitted from the cyclotron accelerator 83, and includes a
plurality of metal plates with different thickness (not
illustrated). These metal plates are movable in a direction
perpendicular to the beam path 16. One or more of such metal plates
with different thicknesses is inserted into the beam path 16 across
the beam path 16, thereby controlling the attenuation amount of
energy of the ion beam traveling through the beam path 16. As a
result, the energy of the ion beam to be delivered to the target
volume of the patient 70 can be changed and the ion beam can be
delivered to each layer existing in the target volume in the depth
direction.
[0140] In this embodiment, the movable floor 36 includes the X-ray
transmission plates 39 and 40, the X-ray sources 71A and 71B and
the collimators 77A and 77B are attached to the outer surface of
the rotary drum 29, and the X-ray detection systems 72A and 72B are
attached to the irradiation system 57 and this is similar to the
first embodiment.
[0141] The particle therapy system 1B according to this embodiment
can provide the effect obtained in the first embodiment.
[0142] In the second and third embodiments, the positioning of the
target volume can be carried out before the irradiation with the
ion beam as described in the first embodiment, and additionally,
the position of the target volume and the effect from the
irradiation with the ion beam can be known during the irradiation
of the target volume with the ion beam.
* * * * *