 |
Claims  |
|
|
What is claimed is:
1. A therapeutic apparatus comprising: irradiating means for irradiating an
ionized particle beam;
a therapy table on which a patient is mounted;
X-ray computer tomography means for accumulating image data;
means responsive to said image data from said X-ray computer tomography
means for generating a first image of at least part of the patient
indicating the position of an affected part;
first display means for displaying said first image generated by said X-ray
computer tomography means;
X-ray means for generating a second image of at least part of the patient
indicating the position of said ionized particle beam, said second image
being a center projection image formed on a plane when the patient is
projected by an X-ray radiating from a point;
second display means for displaying said second image generated by said
X-ray means;
input means for inputting positional information indicative of locations of
reference points of physical characteristics in said first image and said
second image, said physical characteristics being identified on said
second image and the positions of said reference points being related to
the position of said affected part;
computing means for calculating the distance of movement of the therapy
table such that said ionized particle beam is irradiated onto said
affected part of the patient on the basis of said positional information
of said first image and said second image and for calculating the shape,
dose, and energy of said ionized particle beam; and
means for moving the patient relative to said ionized particle beam on the
basis of said calculated distance.
2. The apparatus of claim 1, wherein said physical characteristics
comprises a bone.
3. The apparatus of claim 1, further comprising a range shifter for varying
the energy of the ionized particle beam thereby to change the range of the
ionized beam to coincide with the depth of the affected part.
4. A method of using a therapeutic apparatus comprising ionized particle
beam irradiating means mounted along a vertical projection axis, a therapy
table, X-ray computer tomography means, first display means, X-ray means,
second display means, input means, computer means, and means for moving
the therapy table means, comprising the steps of:
positioning a patient on the therapy table;
accumulating image data using the X-ray computer tomography means;
generating a first image of at least part of the patient indicating the
position of an affected part;
displaying said first image on the first display means;
inputting a first set of reference marks, with the input means, indicative
of locations of physical characteristics of said first image displayed on
the first display means;
calculating the distances between said affected part and said first set of
reference marks;
generating a second image, using the X-ray means, of at least part of the
patient illustrating a position of the vertical projection axis, said
second image being a center projection image formed on a plane when the
patient is projected by an X-ray radiation from a point;
displaying said second image on the second display means;
inputting a second set of reference marks, with the input means, indicative
of this locations of said physical characteristics of said second image
displayed on the second display means, said physical characteristics being
identified on said second image and the positions of said reference marks
being related to the position of said affected part;
calculating a distance of movement of the therapy table using the computer
means, such that said affected part and the vertical projection axis
coincide, on the basis of said first and second reference marks and
calculating the shape, dose and energy of an ionized particle beam to be
irradiated on the patient;
moving the therapy table said calculated distance of movement; and
irradiating the patient with an ionized particle beam of said calculated
shape, dose, and energy.
5. A therapeutic apparatus comprising:
irradiating means for irradiating an ionized particle beam;
a therapy table on which a patient is mounted;
first X-ray computer tomography means for accummulating image data;
means responsive to said image data from said first X-ray computer
tomography means for generating a first image of at least part of the
patient indicating the position of an affected part;
first display means for displaying said first image generated by said first
X-ray computer tomography means;
second X-ray computer tomography means for generating a second image of at
least part of the patient indicating the position of said ionized particle
beam, said second image being a center projection image formed of a plane
of the patient;
second display means for displaying said second image generated by said
second X-ray computer tomography means;
input means for inputting positional information indicative of locations of
reference points of physical characteristics in said first image and said
second image, said physical characteristics being identified on said
second image and the positions of said reference points being related to
the positions of said affected part;
computing means for calculating the distance of movement of the therapy
table such that said ionized particle beam is irradiated onto said
affected part of the patient on the basis of said positional information
of said first image and said second image and for calculating the shape,
dose, and energy of said ionized particle beam; and
means for moving the patient relative to said ionized particle beam on the
basis of said calculated distance.
6. A method of using a therapeutic apparatus comprising particle beam
irradiating means mounted along a vertical projection axis, a therapy
table, first X-ray computer tomography means, first display means, second
X-ray computer tomography means, second display means, input means,
computer means, and means for moving the therapy table means, comprising
the steps of:
positioning a table on the therapy table;
accummulating image data using the first X-ray computer tomography means;
generating a first image of at least part of the patient indicating the
position of an affected part;
displaying said first image on the first display means;
inputting a first set of reference marks, with the input means, indicative
of locations of physical characteristics of said first image displayed on
the first display means;
calculating the distances between said affected part and said first set of
reference marks;
generating a second image, using the second X-ray computer tomography
means, of at least part of the patient illustrating a position of the
vertical projection axis, said second image being a center projection
image formed on a plane of the patient;
displaying said second image on the second display means;
inputting a second set of reference marks, with the input means, indicative
of the locations of said physical characteristics of said second image
displayed on the second display means, said physical characteristics being
identified on said second image and the positions of said reference marks
being related to the position of said afected part;
calculating a distance of movement of the therapy table, using the computer
means such that said affected part and the vertical projection axis
coincide, on the basis of said first and second reference marks and
calculating the shape, dose and energy of an ionized particle beam to be
irradiated on the patient;
moving the therapy table said calculated distance of movement; and
irradiating the patient with an ionized particle beam of said calculated
shape, dose, and energy. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
BACKGROUND OF THE INVENTION
The present invention relates to a therapeutic apparatus including a
therapeutic radiation source emitting a therapeutic radiation beam such as
an ionized particle beam (beam of ionized particles), a heavy particle
beam (baryon beam) or a neutron beam, for irradiation onto the part of the
patient affected by a malignant tumor, such as cancer (carcinoma).
In this type of therapeutic apparatus, the therapeutic radiation beam,
e.g., ionized particle beam, accelerated by a cyclotron is guided to the
therapy room where the patient is fixed to a therapy table such as a
therapy chair or a therapy bed. Prior to irradiation, the therapy table
must be positioned accurately such that the affected part is in alignment
with the therapeutic radiation beam. It is desirable that this positioning
be made in a simple manner and in a short time. The radiation dose must be
accurately controlled. The area of irradiation must be accurately defined
such that the irradiation field coincides with the extension of the
affected part. The energy of the beam must also be controlled and varied
during irradiation such that the range, i.e., the depth of irradiation or
penetration into the patient, matches the location and extension of the
affected part within the body of the patient.
Prior art therapeutic apparatuses of this type were not satisfactory with
respect to one or more of the above requirements.
SUMMARY OF THE INVENTION
An object of the invention is to provide improvements in a therapeutic
apparatus.
Another object of the invention is to provide a therapeutic apparatus which
meets various requirements set forth above.
Another object of the invention is to enable accurate and quick positioning
of the patient with respect to the therapeutic radiation beam.
Another object of the invention is to enable accurate control over
irradiation dose.
Another object of the invention is to enable accurate definition of the
beam.
Another object of the invention is to enable accurate control and variation
of the energy of the therapeutic radiation beam.
Another object of the invention is to provide a uniform dose distribution
of an ionized particle beam over an enlarged irradiation field.
Another object of the invention is to provide an iris for the ionized
particle beam with equal effectiveness for all directions.
Another object of the invention is to enable detection of the location at
which the irradiation actually occurs.
Another object of the invention is to enable positioning of the light field
localizer nearer to the patient.
Another object of the invention is to reduce the loss of the energy of a
particle beam in the measurement of the particle beam.
Another object of the invention is to improve the accuracy of the
monitoring of a particle beam.
Another object of the invention is to provide a range adjuster having an
absorption member of which the thickness can be varied continuously.
Another object of the invention is to eliminate the necessity of providing
a ridge filter and a bolus for individual patients.
Another object of the invention is to enable three-dimensional irradiation
of a particle beam in conformity with the shape of the affected part.
Another object of the invention is to provide a uniform dose distribution
with respect to the depth within the body.
Another object of the invention is to provide a bed which eliminates the
need of moving the patient between the diagnosis using a slice image
pick-up device and irradiation therapy using a particle beam therapeutic
apparatus.
According to the invention there is provided a therapeutic apparatus
comprising:
irradiating means for irradiating a therapy beam;
a therapy table on which a patient is mounted;
first image pick-up means for picking up an image of at least part of the
patient indicating the position of an affected part;
first display means for displaying a first image taken by said first image
pick-up means;
second image pick-up means for picking up an image of at least part of the
patient indicating the position of the therapy beam;
second display means for displaying a second image taken by said second
image pick-up means;
input means for inputting positional information of the affected part for
indication in said first image and said second image;
computing means for calculating the distance of movement of the therapy
table such that the therapy beam is irradiated onto the affected part of
the patient on the basis of said first image and said second image with
said positional information; and
means for moving said patient relative to said therapy beam on the basis of
the calculated distance.
According to another aspect of the invention, there is provided a method of
positioning a therapeutic beam comprising the steps of:
determining a first distance from a first predetermined position other than
an affected part of a patient to the affected part on the basis of a first
image including at least part of the patient and indicating the position
of the affected part of the patient;
determining a second distance from a second predetermined position
corresponding to said first predetermined position to a position of the
therapy beam on the basis of a second image including at least part of the
patient and indicating the position of the therapy beam; and
moving the patient such that the therapy beam is irradiated onto the
affected part, on the basis of said first distance and said second
distance.
According to another aspect of the invention, there is provided an ionized
particle beam apparatus comprising:
first and second scanning electromagnets for deflecting an ionized particle
beam in directions orthogonal to each other;
means for applying AC currents to said first and second scanning
electromagnets to generate a rotating magnetic field thereby to rotate
said ionized particle beam,
said ionized particle beam being irradiated in an irradiation field; and
a scattering member disposed on the path of said ionized particle beam,
either upstream or downstream of said first and second scanning
electromagnets for enlarging the radius of the area over which said
ionized particle beam is irradiated.
According to another aspect of the invention, there is provided an ionized
particle beam apparatus comprising:
slit assembly means having pairs of slit pieces, the slit pair of each
pairs being movable back and forth opposite to each other to adjust the
size of the beam that is irradiated onto an irradiated part;
an aperture defined by the inner edges of slit pieces determining the
profile of the ionized particle beam; and
means for moving the slit pieces of each pair toward and away from each
other,
wherein the inner edge of each of the slit pieces are generally concave
toward the center of the aperture.
According to another aspect of the invention, there is provided an ionized
particle beam cancer therapeutic apparatus comprising:
means for irradiating an ionized particle beam onto a cancer affected part;
means for changing the configuration of the irradiation field;
a light source for use in confirmation of the changed irradiation field;
and
a lens system disposed between the light source and the patient,
whereby the light source is disposed near the patient.
According to another aspect of the invention, there is provided a particle
beam monitor device comprising:
an insulating plate;
a high-voltage electrode; and
a collector electrode disposed opposite to said high-voltage electrode with
the insulating plate interposed between them in a housing filled with a
gas,
wherein said collector electrodes are formed by plating or evaporating
metal on a resin plate.
According to another aspect of the invention, there is provided a particle
beam monitor device comprising:
an insulating plate;
a high-voltage electrode; and
a collector electrode disposed opposite to said high-voltage electrode with
the insulating plate interposed between them in a housing filled with a
gas,
said collector electrode being formed by plating or evaporating metal on a
resin plate;
an additional collector electrode formed by plating or evaporating metal on
a resin plate; and
an additional high-voltage electrode positioned opposite to said additional
collector electrode with an insulating plate interposed between them.
According to another aspect of the invention, there is provided a range
adjuster for use in a particle beam therapeutic apparatus for irradiating
an ionized particle beam for killing cancer cells comprising:
first and second wedge-shaped energy absorption members stacked with each
other, with the directions in which said wedge-shaped members being
tapered and opposite to each other; and
means for moving the wedge-shaped members back and forth in the directions
in which said wedge-shaped members are tapered to vary the total thickness
of the absorption members through which the particle beam must pass.
According to another aspect of the invention, there is provided an ionized
particle beam cancer therapy apparatus for irradiating an ionized particle
beam onto a cancer affected part for the purpose of therapy, comprising:
a range shifter for varying the energy of ionized particle beam; and
a collimator for varying the shape of the irradiation in a plane
perpendicular to the path of the beam,
said range shifter and said collimator being disposed on the path of the
beam,
whereby the three-dimensional irradiation is conducted in conformity with
the shape of the affected part.
According to another aspect of the invention, there is provided a method of
irradiating an ionized particle beam in which irradiation is successively
made for different depths, comprising the steps of:
using a radiation beam having a range peak at a certain depth and a lower
range distribution in the shallower part; and
giving smaller irradiation does for shallower parts so that the total dose
taking account of the lower distribution at the part shallower than the
position of the range peak is constant throughout the entire depth of the
affected part.
According to another aspect of the invention, there is provided a
therapy/diagnosis bed comprising:
a bed main body on which a patient is mounted; and
means for moving said bed main body between a medical slice image pick-up
device and a particle beam therapy apparatus, with said patient fixed to
said bed main body,
whereby diagnosis by use of said medical slice image pick-up device and
therapy by use of said particle beam therapy apparatus are both enabled.
Further scope of applicability of the present invention will become
apparent from the detailed description given hereinafter. However, it
should be understood that the detailed description and specific examples,
while indicating preferred embodiments of the invention, are given by way
of illustration only, since various changes and modifications within the
spirit and scope of the invention will become apparent to those skilled in
the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed
description given hereinbelow and the accompanying drawings which are
given by way of illustration only, and thus, are not limitative of the
present invention, and wherein:
FIG. 1 is a schematic diagram showing a therapeutic apparatus according to
an embodiment of the invention.
FIG. 2 is a schematic diagram showing the flow of operations of the
therapeutic apparatus of FIG. 1.
FIG. 3 shows the reference image on the X-Y plane at (A), and the
corresponding X-ray TV image at (B).
FIG. 4 is a diagram for explaining the relationship between the coordinate
values and the true coordinate values on the X-Y plane.
FIG. 5 shows the reference image on the Z-X plane at (A) and the
corresponding X-ray TV image at (B).
FIG. 6 is a schematic diagram showing a therapeutic apparatus according to
another embodiment of the invention.
FIGS. 6A and 6B illustrate the reference image on the z-x plane and the
corresponding X-ray CT slice image respectively, of the embodiment
illustrated in FIG. 6.
FIG. 7 is a schematic diagram showing an ionized particle beam apparatus
which may be incorporated in the therapeutic apparatus shown in and
described with reference to FIG. 1 to FIG. 6.
FIG. 8 is a diagram showing dose distribution when the ionized particle
beam apparatus of FIG. 7 is employed.
FIG. 9 is a diagram showing another embodiment of an ionized particle beam
apparatus which may be incorporated in the therapeutic apparatus shown in
and described with reference to FIG. 1 to FIG. 6.
FIG. 10 is a diagram showing dose distribution when the ionized particle
beam apparatus of FIG. 9 is employed.
FIG. 11 shows how a slit assembly can be disposed in an ionized particle
beam apparatus.
FIG. 12 shows an example of a slit assembly.
FIG. 13 shows another example of a slit assembly.
FIG. 14 shows an apparatus for measuring the dose and/or location of the
irradiation.
FIG. 15 shows an example of absorption dose distribution of the ionized
particle beam.
FIG. 16 is an elevational view showing another embodiment of an ionized
particle beam therapeutic apparatus.
FIG. 17 is an elevational view showing another embodiment of an ionized
particle beam therapeutic apparatus.
FIG. 18A is a side view showing a particle beam monitor device.
FIG. 18B is a diagram showing the uniformity measurement electrodes.
FIG. 18C is a diagram showing the profile measurement electrodes.
FIG. 19 is a side view showing another example of a particle beam monitor
device.
FIG. 20 shows how a high-voltage power supply is connected to the particle
beam monitor device.
FIG. 21 shows another example of a particle beam monitor device.
FIG. 22 is an enlarged diagram showing the collector electrode in FIG. 21.
FIG. 23 is a bottom view of the device shown in FIG. 22.
FIG. 24 is a plan view showing another example of a particle beam monitor
device.
FIG. 25 is diagram showing the dose distribution in relation to the
irradiation depth (range).
FIG. 26 is a cross sectional view showing an example of a range adjuster.
FIG. 27 is a schematic side view of another example of a range adjuster.
FIG. 28 is an elevational view of another embodiment of an ionized particle
beam cancer therapy apparatus.
FIG. 29 is a characteristic diagram showing the absorption dose of the
ionized particle beam.
FIG. 30 is a characteristic diagram showing another example of an
absorption dose of the ionized particle beam.
FIG. 31 is a cross sectional view of a ridge filter.
FIG. 32A and FIG. 32B are schematic diagrams showing the operation of a
multileaf (multiple-leaf) collimator
FIG. 33 is a schematic diagram showing the operation of the bolus.
FIG. 34 is a schematic elevational view showing another embodiment of an
ionized particle beam cancer therapeutic apparatus.
FIG. 35 is a schematic diagram showing the operation of the range shifter
and the multileaf collimator.
FIG. 36 is a schematic diagram showing the operation of the range shifter
and the multileaf collimator corresponding to the respective layers of the
affected part.
FIG. 37 shows the progress, with time, of the above operations.
FIG. 38 is a flow chart showing the operation of the irradiation.
FIG. 39 is a time chart showing a series of beam pulses.
FIG. 40 is a graph showing the dose distribution with respect to the depth
in the body when the dose of irradiation for different depths is not
changed.
FIG. 41 is a graph showing the dose distribution with respect to the depth
in the body when the dose of irradiation for different depths is adjusted.
FIG. 42 is a schematic diagram of another embodiment of an ionized particle
beam therapeutic apparatus.
FIG. 43 is an elevational view showing a therapy and diagnosis system
including a therapy/diagnosis bed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an embodiment of a therapeutic apparatus according to the
invention. As illustrated, it comprises an irradiation apparatus including
a vertical irradiation unit 6, a range shifter 7, a dose monitor 8, and a
collimator 9, which are aligned along a beam axis 1 perpendicular to the
ground surface and in the above-stated order toward the ground. The range
shifter 7 is disposed inside the vertical irradiation unit 6. The
illustrated therapeutic apparatus also comprises a first image pick-up
device including an X-ray CT (computed tomography) unit 11 connected to a
computer 19 through a communication device 29, a data bus 28, and another
communication device 27. The therapeutic apparatus of the illustrated
embodiment further comprises a second image pick-up device including an
X-ray tube 2, an X-ray tube controller 12, an image intensifier 13, an
optical system 14, an auto-iris 15, a television camera 16 and a camera
control unit 17. The above-listed members, except for the X-ray controller
12 connected to the X-ray tube 2 and the camera control unit 17 connected
to the television camera 16, are aligned in the above-stated order, along
the beam axis 1 toward the ground. The X-ray tube 2 is disposed between
the dose monitor 8 and the collimator 9, and the collimator 9 is disposed
between the X-ray tube 2 and the image intensifier 13. An
analog-to-digital converter 18 is connected to the camera control unit 17.
A computer 19 is connected to the analog-to-digital converter 18. A
reference image display unit 20 and a pick-up image display unit 21 are
connected to the computer 19. A character display unit 22, a keyboard 23
and an operation panel 24 are also connected to the computer 19. A tablet
25 is also connected to the computer 19 and is used an an input means. An
image data file 26 is connected to the computer 19.
During positioning and during therapy, a therapy table 4 on which a patient
3 is laid in the supine position (with the face upward of "on his back")
is disposed between the collimator 9 and the image intensifier 13. The
therapy table 4 is provided with a built-in drive unit. The therapy table
4 is also connected to the computer 19.
The operation of the above-described therapeutic apparatus is now described
with reference to FIG. 2, which shows the flow of operation of the
therapeutic apparatus. The drawings (A) through (D) on the left show steps
during therapy plannings. The drawings (E) through (H) on the right show
steps during positioning.
During examination, X-ray CT images showing the location of the affected
part of the patient picked up by an X-ray CT unit 11 are transmitted via
the communication device 29, the data bus 28, the communication device 27
and the computer 19, to the image data file 26 and are accumulated in the
image data file 26. As an alternative, the X-ray CT images may be recorded
on a magnetic tape, a floppy disk or similar recording medium, and
subsequently accumulated in the image data file 26.
During therapy planning, the X-ray CT images accumulated in the image data
file 26 (schematically illustrated at (A) in FIG. 2) are converted (as
shown by (B)) into a center projection image, an example of which is shown
at (D) in FIG. 2. A center projection image is an image formed on a plane
when X-rays radiating from a point (X-ray tube), are projected upon the
patient, as shown in (C) in FIG. 2. The center projection image is
displayed on the reference image display unit 20 as reference images.
Using the tablet 25, three land marks Mi (i=1, 2, 3) are added to the
reference images at locations of certain characteristic parts, such as
bones, that can be identified on an image obtained by X-ray projection.
The land marks Mi are used for indexing during positioning. In this
connection, it should be noted that the affected part cannot be identified
on an image obtained by X-ray projection. The computer 19 calculates the
distances between the affected part K (indicated by hatching) and the land
marks Mi. More than three land marks Mi may be used instead of just three,
to increase the accuracy of the positioning.
During the positioning, a shown at (E) in FIG. 2, the patient 3 on the
therapy table 4 is irradiated with an X-ray from the X-ray tube 2 having
the voltage controlled by the X-ray controller 12. The X-ray images of the
patient 3 of which the beam axis 1 can be identified are converted into
optical images by the image intensifier 13. The optical images are then
guided by the optical system 14, passed through the auto-iris 15, which
automatically controls the iris of the television camera 16, and picked up
by the television camera 16, thereby to be converted into electrical
analog signals. The analog signals are converted by the analog-to-digital
converter 18 into digital signals, which are then supplied to the computer
19. The computer 19 serves to perform signal processing. This signal
processing includes correction or compensation for the periphery error (or
pincushion distortion error). After the signal processing, the optical
images are displayed on the pick-up image display unit 21. Land marks Ni
(i=1, 2, 3) are appended to the X-ray TV image by input with the tablet
25. The computer 19 then calculates the distances between the center 0 of
the beam axis 1 and the land marks Ni, and the distances between the
affected part K and the center 0 of the beam axis 1. That is, as shown at
(H) in FIG. 2, the distance that the therapy table 4 must move so that the
affected part K coincides with the center 0 of the beam axis 1 is
calculated. Moreover, the shape, dose and energy of the beam of the
ionized particle beam are calculated by the reference image and the X-ray
TV image. Control signals indicating the distance of the movement are
supplied to the therapy table 4, which is thereby moved such that the
ionized particle beam is accurately irradiated onto the affected part K.
During the actual therapy, the shape and depth of the affected part K, and
the irradiated ionized particle beam absorption characteristic (absorption
dose) are the parameters of the cancer therapy. On the basis of these, the
ionized particle beam is controlled by the collimator 9, the range shifter
7, and the dose monitor 8, and irradiated onto the affected part K. More
specifically, the ionized particle beam is reformed to have the shape
coincident with the shape of the affected part K, and the energy of the
ionized particle beam is varied through passage of a material with
distributed (varied) energy absorption of the range shifter 7 and the
range is thereby varied. The dose of irradiation of the ionized particle
beam is monitored by use of the dose monitor 8. During such operation, the
X-ray tube 2 is removed or retracted such that it does not interfere with
the ionized particle beam.
An embodiment of the invention is now described with reference to FIG. 3,
FIG. 4, and FIG. 5. FIG. 3 shows the reference image on the X-Y plane at
(A), and the corresponding X-ray TV image at (B). FIG. 4 is a diagram for
explaining the relationship between the coordinate values and the true
coordinate values on the X-Y plane. FIG. 5 shows the reference image on
the Z-X plane at (A) and the corresponding X-ray TV image at (B).
The method of positioning by use of the X-ray TV image is as follows:
(1a) As shown if FIG. 3 at (A), the reference image is displayed on the
reference image display unit 20. The hatched affected part K, the center A
of the affected part K, the land marks Mi, and the distances Ri (i=1, 2,
3) from the center A of the affected part K to the land marks Mi are
indicated.
(1b) As shown in FIG. 3 at (B), the X-ray image of the patient 3 is formed
and displayed on the pick-up image display unit 21, after correction of
the peripheral distortion of the digitized X-ray image. The X-ray TV image
includes the profile of bones or the like (but the profile of the affected
part K is not seen in the X-ray TV image), the center 0 of the beam axis
1, i.e., the center of X-ray TV image,) and X and Y axes. The center 0 of
the beam axis 1 in the X-ray image is made to be at a position
corresponding to the affected part K in the reference image.
(1c) As shown in FIG. 3 at (B), land marks Ni are appended to the X-ray TV
image, by use of the tablet 25, at the positions corresponding to the land
marks Mi on the reference image shown in FIG. 3 at (A). Apart from the
image elements mentioned above, the affected part that is hatched, the
estimated center B of the affected part, and the land marks Ni are also
indicated in FIG. 3 at (B).
(1d) The distance of the movement of the therapy table 4 in a direction
parallel to the X-Y plane is calculated. As shown in FIG. 3 at (B), the
distance of the movement is represented by vector .fwdarw.OB (generally
the vector from the coordinate P to the coordinate Q is represented by
.fwdarw.PQ).
.fwdarw.AMi=Ri (1)
.fwdarw.BNi=-.fwdarw.OB+.fwdarw.ONi (2)
From the equation (2),
.fwdarw.OB=.fwdarw.ONi-.fwdarw.BNi (3)
Since .fwdarw.BNi=.fwdarw.AMi=Ri
.fwdarw.OB=.fwdarw.ONi-Ri
The values of .fwdarw.ONi start at the coordinate shown in FIG. 3 at (B).
(1e) The angle of rotation (rotational error) about the Z-axis of the
therapy table 4 is calculated. In addition to the image elements shown in
FIG. 3, the true center At of the affected part and the true land mark Mt3
are indicated in the reference image, and the true estimated center Bt of
the affected part and the true land mark Nt3 are indicated in the X-ray TV
image, as shown in FIG. 4. Moreover, the heights H, H1 and H2 of the X-ray
tube 2, the true affected part center At (true estimated affected part
center Bt) and the true land mark Mt3 (true land mark Nt3), with respect
to the image pick-up plane of the patient 3 are also indicated.
First, the true affected part center Bt corresponding to the estimated
affected part center B is calculated. Specifically, the true distances Rti
(i=1, 2, 3) from the true land marks Nti (i=1, 2, 3) to the true affected
part center Bt are calculated.
For example, as shown in FIG. 4,
(.fwdarw.ON3-.fwdarw.ONt3)/.fwdarw.ON3=H1/H (4)
(.fwdarw.OB-.fwdarw.OBt)/.fwdarw.OB=H2H (5)
From the equations (4) and (5), the angle of rotation .theta. of the
affected part is calculated by averaging the angle differences between the
.fwdarw.AtMti (i=1, 2, 3) and .fwdarw.BtNti.
(1f) The therapy table 4 is moved by .fwdarw.OB in the X- and Y-axes and
rotated by .theta. about the Z-axis. The positioning is thereby achieved.
In practice, the distance .fwdarw.OB of movement is displayed on the
character display unit 22, on the basis of which the therapy table 4 is
moved under manipulation by the operator (technical expert).
The positioning on the Z-X plane and/or Y-Z plane can be made in a manner
similar to the above, if that is required.
(1g) As shown in FIG. 5, at (A) and (B), land marks Ni are appended in the
X-ray TV image, at positions corresponding to the land marks Mi in the
reference image, and the distance .fwdarw.OB of required movement in the
Z-axis is calculated.
(1h) The therapy table 4 is moved by the distance of movement .fwdarw.OB in
the Z-axis direction (up and down directions). The positioning is thereby
achieved.
This completes the positioning by use of the X-ray TV image. When minute
adjustment is required, the steps (1a) through (1h) can be repeated. The
final confirmation is made by a doctor.
FIG. 6 shows another embodiment of the therapeutic apparatus according to
the invention. This embodiment differs from therapeutic apparatus of the
FIG. 1 in that the second image pick-up means is formed of an X-ray CT
unit 13A, which is disposed on the beam axis 1, and the X-ray CT slice
image picked up/obtained by the X-ray CT unit 13A is supplied to the
computer 19.
The method of positioning by use of the X-ray CT images is described with
reference of FIG. 6A and FIG. 6B. FIG. 6A shows the reference image on the
Z-X plane and FIG. 6B shows the corresponding X-ray CT slice image.
(2a) As shown in FIG. 6A, the reference image is displayed on the reference
image display unit 20. The reference image is obtained by appending land
marks Mi, by use of the tablet 25, to slice image that has not been
transformed into a center projection image. In FIG. 6A, the affected part
is shown hatched, and the affected part center A, land marks Mi and the
image center Or are indicated.
(2b) As shown in FIG. 6B, a plurality of slice images, including the
affected part, are obtained by the X-ray CT unit 13A, and displayed on the
pick-up image display unit 21. In FIG. 6B, the affected part is shown
hatched, and the estimated affected part center B, land marks Ni and the
image center (irradiation center) O, and Z- and Y-axes are indicated.
(2c) The X-ray CT slice images are successively displayed on the pick-up
image display unit 21, and the X-ray CT slice image which coincides (most
closely) with the reference image is selected by eye observation. From the
number (representing the depth at which the X-ray CT slice image is taken)
of the X-ray CT slice image that has been selected, the position along the
X-axis of the affected part is determined.
(2d) Land marks Ni are appended, by use of the tablet 25, to the selected
X-ray CT slice image at positions corresponding to the land marks Mi in
the reference image. As a result, the affected part center B in the Z-Y
plane is determined in the same manner as with the X-ray TV image.
(2e) The averages .fwdarw.MN of the vectors (deviations) .fwdarw.MiNi (i=1,
2, 3) of the land marks Mi and Ni with respect to the the image centers Or
and O of the reference image and X-ray CT slice image, respectively, are
calculated. The distances .fwdarw.OB of movement in the Z-Y axis
directions of the therapy table 4 can thereby be determined. That is, the
distance of the movement is given by:
.fwdarw.OB=.fwdarw.OrA+.fwdarw.MN (6)
(2f) The therapy table 4 is moved by the distance .fwdarw.OB in the Z-Y
axis directions, and the positioning is thereby accomplished.
(2g) The therapy table 4 is moved by the necessary distance (as determined
in the step (2c)) in the X axis direction, and the positioning is thereby
accomplished.
This completes the positioning by use of the X-ray CT slice image. In this
embodiment, becasue of the restriction against rotation of the therapy
table 4 about the X axis, the rotational error cannot be corrected during
the positioning in the Z-Y plane.
In this way, accurate positioning can be made in a simple manner and
automatically. After the positioning the therapy using the ionized
particle beam can be made in a manner known in the art, or in a manner
described later in this specfication.
In the positioning using the X-ray TV images, the reference image and the
center projection image are required. The X-ray TV image data (with land
marks Mi) obtained by the processing at the time of therapy planning at
the first occasion are transmitted to the computer 19, and can be used as
the reference image in the subsequent occasion. This eliminates the
transformation into the center projection image.
In the positioning using the X-ray CT slice images, the X-ray CT scanogram
may be used as the reference image. In this case, a three-dimensional
slice image can be obtained. The positioning in the X-Y plane can be made
efficiently. However, with the X-ray CT scanogram, a measure may be
required for correcting the image distortion due to the difference in the
aperture of the X-ray CT unit.
FIG. 7 shows an example of an ionized particle beam a | | |
