U.S. patent application number 15/412958 was filed with the patent office on 2017-05-11 for frameless radiosurgery treatment system and method.
The applicant listed for this patent is ACCURAY INCORPORATED. Invention is credited to John R. Adler, Achim Schweikard.
Application Number | 20170128744 15/412958 |
Document ID | / |
Family ID | 24660487 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170128744 |
Kind Code |
A1 |
Adler; John R. ; et
al. |
May 11, 2017 |
FRAMELESS RADIOSURGERY TREATMENT SYSTEM AND METHOD
Abstract
A method of compensating for breathing and other motions of a
patient during treatment includes periodically generating internal
positional data about an internal target region. The method further
includes generating external positional data about external motion
of the patient's body using an external sensor and generating a
correlation between one or more positions of the internal target
region and one or more positions of an external region using the
external positional data of the external sensor and the internal
positional data of the internal target region. The method further
includes predicting the position of the internal target region at
some later time based on the correlation model.
Inventors: |
Adler; John R.; (Stanford,
CA) ; Schweikard; Achim; (Hamburg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ACCURAY INCORPORATED |
Sunnyvale |
CA |
US |
|
|
Family ID: |
24660487 |
Appl. No.: |
15/412958 |
Filed: |
January 23, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14133111 |
Dec 18, 2013 |
9572997 |
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15412958 |
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13306951 |
Nov 29, 2011 |
8634898 |
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14133111 |
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12356442 |
Jan 20, 2009 |
8086299 |
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13306951 |
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10919765 |
Aug 17, 2004 |
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12356442 |
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09663104 |
Sep 15, 2000 |
6778850 |
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10919765 |
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09270404 |
Mar 16, 1999 |
6144875 |
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09663104 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61N 5/1048 20130101;
A61B 90/39 20160201; A61N 2005/1061 20130101; A61B 18/20 20130101;
A61N 5/103 20130101; A61N 5/1067 20130101; A61B 2090/376 20160201;
A61B 34/20 20160201; A61N 5/1049 20130101; A61B 90/10 20160201;
A61B 2017/00699 20130101; A61N 5/1064 20130101; A61B 2034/2055
20160201; A61B 2017/00694 20130101; A61B 6/12 20130101; A61B
2090/3983 20160201; A61B 2034/2072 20160201; A61B 6/4458 20130101;
A61B 6/527 20130101; A61B 10/0233 20130101; A61B 2090/101 20160201;
A61N 7/02 20130101 |
International
Class: |
A61N 5/10 20060101
A61N005/10; A61B 90/10 20060101 A61B090/10; A61B 34/20 20060101
A61B034/20; A61B 6/12 20060101 A61B006/12; A61B 6/00 20060101
A61B006/00 |
Claims
1. A method comprising: generating internal positional data about
an internal target region in a patient at a plurality of times at a
first time interval; generating external positional data about
motion of an external region of the patient's body using an
external sensor at a plurality of times at a second time interval,
wherein the second time interval is different than the first time
interval; determining a correlation between one or more positions
of the internal target region and one or more positions of the
external region using the external positional data of the external
sensor and the internal positional data of the internal target
region; predicting a future position of the internal target region
based on the determined correlation; and controlling a treatment
delivery based on the determined correlation.
2. The method of claim 1, wherein controlling the treatment
delivery comprises moving a treatment table.
3. The method of claim 1, further comprising: generating a series
of preoperative images for both the internal target region and the
external region of the patient's body; and generating an initial
correlation model based on the series of preoperative images prior
to treatment of the patient.
4. The method of claim 3, further comprising: generating new
internal positional data and new external positional data during
the treatment delivery; and updating the initial correlation model
during the treatment delivery by recomputing the initial
correlation model based on the new internal positional data and the
new external positional data.
5. The method of claim 1, wherein controlling the treatment
delivery comprises: activating a treatment beam based on a
correlation model generated from the correlation so that the
treatment beam is switched on and off periodically.
6. The method of claim 1, wherein the internal positional data
comprises data for one or more fiducial markers located near the
internal target region, the method further comprising: generating a
correlation model from the correlation based on computing a
deformation state of the internal target region based on relative
positions of the one or more fiducial markers.
7. The method of claim 1, wherein controlling the treatment
delivery comprises: moving a treatment beam generator based on the
correlation.
8. The method of claim 1, wherein controlling the treatment
delivery comprises: moving a collimating device to change
characteristics of a treatment beam based on the correlation.
9. An apparatus, comprising: a first detection device to generate
internal positional data about an internal target region in a
patient at a plurality of times at a first time interval; a second
detection device to generate external positional data, about motion
of an external region of the patient's body using an external
sensor, at a plurality of times at a second time interval, wherein
the second time interval is different than the first time interval;
and a processor, operatively coupled to the first detection device
and to the second detection device, to: determine a correlation
between one or more positions of the internal target region and one
or more positions of the external region using the external
positional data of the external sensor and the internal positional
data of the internal target region; predict a future position of
the internal target region based on the determined correlation; and
control a treatment delivery based on the determined
correlation.
10. The apparatus of claim 9, further comprising: a treatment beam
generator, operatively coupled to the processor, to generate a
treatment beam, the treatment beam generator to activate the
treatment beam periodically based on the correlation.
11. The apparatus of claim 9, wherein: the internal positional data
comprises data for one or more fiducial markers located near the
internal target region; and the processor is to generate a
correlation model from the correlation based on computing a
deformation state of the internal target region based on relative
positions of the one or more fiducial markers.
12. The apparatus of claim 9, further comprising: a treatment beam
generator, operatively coupled to the processor, to generate a
treatment beam, wherein the processor to control the treatment beam
generator to move the treatment beam generator in accordance with
the correlation.
13. The apparatus of claim 9, further comprising: a treatment beam
generator, operatively coupled to the processor, to generate a
treatment beam; and a collimating device, operatively coupled to
the treatment beam generator, wherein the processor to control the
treatment beam by changing characteristics of the treatment beam
based on the correlation.
14. The apparatus of claim 9, wherein to control the treatment
delivery, the processor is to move a treatment table.
15. A non-transitory computer readable storage medium comprising
instructions that, when executed by a processor, cause the
processor to: receive, by the processor, internal positional data
about an internal target region in a patient, the internal
positional data having been generated at a plurality of times at a
first time interval; receive, by the processor, external positional
data about motion of an external region of the patient's body, the
external positional data having been generated, using an external
sensor, at a plurality of times at a second time interval, wherein
the second time interval is different than the first time interval;
determine, by the processor, a correlation between one or more
positions of the internal target region and one or more positions
of the external region using the external positional data of the
external sensor and the internal positional data of the internal
target region; predict, by the processor, a future position of the
internal target region based on the determined correlation; and
control a treatment delivery based on the determined
correlation.
16. The non-transitory computer readable storage medium of claim
15, wherein to control the treatment delivery, the processor is to
move a treatment table.
17. The non-transitory computer readable storage medium of claim
15, wherein to control the treatment delivery, the processor to
move a treatment beam generator to redirect a treatment beam to the
future position of the internal target region.
18. The non-transitory computer readable storage medium of claim
15, wherein to control the treatment delivery, the processor to
move a collimating device to change characteristics of a treatment
beam, generated by the treatment bean generator, based on the
correlation.
19. The non-transitory computer readable storage medium of claim
15, the processor further to: receive new internal positional data
and new external positional data during the treatment delivery; and
update the initial correlation model during the treatment delivery
by recomputing the initial correlation model based on the new
internal positional data and the new external positional data.
20. The non-transitory computer readable storage medium of claim
15, wherein to control the treatment delivery, the processor to:
activate a treatment beam based on a correlation model generated
from the correlation to periodically switch on and off the
treatment beam.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/133,111, filed Dec. 18, 2013, which is a
continuation of U.S. patent application Ser. No. 13/306,951, filed
Nov. 29, 2011, now U.S. Pat. No. 8,634,898, issued Jan. 21, 2014,
which is a continuation of U.S. patent application Ser. No.
12/356,442, filed Jan. 20, 2009, now U.S. Pat. No. 8,086,299 issued
Dec. 27, 2011, which is a continuation of U.S. patent application
Ser. No. 10/919,765, filed Aug. 17, 2004, now abandoned, which is a
continuation of U.S. patent application Ser. No. 09/663,104, filed
Sep. 15, 2000, now U.S. Pat. No. 6,778,850, issued Aug. 17, 2004,
which is a continuation in part of U.S. patent application Ser. No.
09/270,404, filed Mar. 16, 1999, now U.S. Pat. No. 6,144,875,
issued Nov. 7, 2000, which are owned by the same assignee as the
present application and all of which are incorporated herein by
reference.
BACKGROUND
[0002] This invention relates generally to a system and method for
treating a patient and in particular to a system and method for
controlling a treatment to administer a precise dose to a patient.
In more detail, the invention relates to an apparatus and method
for performing accurate surgical procedures on a particular target
region within a patient utilizing previously obtained reference
data indicating the position of the target region with respect to
its surrounding which may contain certain reference points.
[0003] In order to control a surgical procedure, such as
radiosurgery, many different prior techniques have been used
including the manual targeting of the treatment. Many of the prior
techniques are not sufficiently accurate so that healthy tissue
surrounding the target region is often unnecessarily irradiated and
damaged or killed. Other techniques are clumsy and cannot be used
for particular types of treatments. For example, one prior
technique involved frame-based stereotaxy that was often used for
body parts and regions that could be easily physically immobilized.
For example, the frame based stereotaxy was often used to
immobilize the head of the patient so that a target region in the
brain, such as a brain tumor, could be irradiated by the
radiosurgical beam. To do so, the patient was positioned on a
treatment bed and then his/her head was immobilized by a frame that
was securely attached to the person's head with some attachment
means and that was also securely attached to an immovable object
such as a treatment table. Thus, during the treatment, the patient
was not able to move his/her head at all which permitted an
accurate targeting of the treatment. The problem is that a
frame-based system cannot be used for fractionated treatment in
which repeated smaller does are given to the patient over some
predetermined period of time, such as a couple of weeks or a month.
A fractionated treatment plan is often desirable since it permits
larger overall doses of treatment, such as radiation, to be applied
to the target region while still permitting the healthy tissue to
heal. Clearly, it is extremely difficult to leave the frame secured
to the patient's head for that period of time. In addition, it is
impossible to remove the frame and later reposition the frame in
the exact same location for the next treatment. Thus, the frame
based stereotaxy provides the desired accuracy, but cannot be used
with various desirable treatment schedules.
[0004] Another typical positioning system is a frameless stereotaxy
system wherein a physical frame attached to the patient is not
necessary. An example of a frameless stereotaxy system is disclosed
in U.S. Pat. No. 5,207,223 which is owned by the same assignee as
the present application and is incorporated herein by reference. In
general, a preoperative imaging of the region surrounding the
target region is completed, such as by computer tomography. Then,
during the treatment, a stereo image is generated, such as by X-ray
imaging. The stereo image is then correlated to the preoperative
image in order to locate the target region accurately. Then, a
radiation source located on a robot is automatically positioned
based on the correlation between the preoperative scans and the
stereo images in order to accurately treat the target region
without--unnecessarily damaging the healthy tissue surrounding the
target region.
[0005] The current frameless stereotaxic techniques have some
limitations which limit their effectiveness. First, most surgical
operation rooms have limited workspace and the current stereotaxic
frameless systems require a large space due to the movement of the
robot supporting the surgical radiation beam and the two beam
imagers Second, the cost of having two beam generators and two
imagers is very high making the treatment system very expensive
These systems also typically require some form of implanted
fiducials, such as markers that are viewable using an X-ray, to
track soft tissue targets. Finally, for most current frameless
systems, breathing and other patient motion may interfere with the
target region identification and tracking due to a degradation of
the images. Thus, it is desirable to provide a frameless
radiosurgery treatment system and method that overcomes the above
limitations and problems and it is to this end that the present
application is directed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a diagram illustrating a typical frameless
radiosurgical treatment system;
[0007] FIG. 2 is a diagram illustrating the diagnostic and
treatment beams of the system shown in FIG. 1;
[0008] FIG. 3 is a block diagram illustrating the treatment system
of FIG. 1;
[0009] FIG. 4 is a diagram illustrating a preferred embodiment of
the frameless treatment system in accordance with the
invention;
[0010] FIG. 5 is a block diagram illustrating more of the details
of the treatment system of FIG. 4;
[0011] FIG. 6 is a flowchart illustrating a method for treatment in
accordance with the invention using the system of FIG. 4;
[0012] FIG. 7 is a diagram illustration a respiration cycle of a
patient;
[0013] FIG. 8 is a flowchart illustrating a method for treating a
patient with respiration tracking in accordance with the
invention;
[0014] FIG. 9 is a diagram illustrating a second embodiment of the
frameless treatment system in accordance with the invention;
[0015] FIG. 10 is a flowchart illustrating a method for treatment
in accordance with the invention using the system of FIG. 9;
[0016] FIG. 11 is a diagram illustrating a third embodiment of the
frameless treatment system in accordance with the invention;
[0017] FIG. 12 is a flowchart illustrating a method for treatment
in accordance with the invention using the system of FIG. 11;
and
[0018] FIG. 13 illustrates the deformation of the pre-treatment
and/or intra-treatment data to establish optimal correspondence to
infer better target positions.
DETAILED DESCRIPTION
[0019] The invention is particularly applicable to a radiosurgical
treatment system and method and it is in this context that the
invention will be described. It will be appreciated, however, that
the system and method in accordance with the invention has greater
utility, such as to other types of treatments wherein it is
necessary to accurately position a treatment at a target, region
within the patient in order to avoid damaging healthy tissue such
as to other types of medical procedures with other types of medical
instruments, such as positioning biopsy needles, ablative,
ultrasound or other focused energy treatments, positioning a laser
beam for laser beam treatment or positioning radioactive seeds for
brachytherapy. Prior to describing the invention, a typical
radiosurgery device will be described to provide a better
understanding of the invention.
[0020] FIGS. 1-3 are diagram illustrating an example of a
stereotaxic radiation treatment device 10. The radiation treatment
device 10 may include a data processor 12, such as a
microprocessor, and a disc or tape storage unit 13 (shown in FIG.
3) which may store a three dimensional image of a patient 14. The
three dimensional image may be loaded into the data processor, if
not already there, to compare the three dimensional image to images
generated during the surgical procedure. The three dimensional
image may be generated by various conventional techniques such as
computer aided tomography (CAT) scan or magnetic resonance imaging
(MR). The radiation treatment device 10 may also include a beaming
apparatus 20 which, when activated, emits a collimated surgical
ionizing beam directed at a target region 18 (shown in FIG. 2). The
collimated surgical ionizing beam may have sufficient strength to
cause the target region to become necrotic. A variety of different
beaming apparatus may be used which generate an ionizing radiation
or heavy particle beam such as a linear accelerator and preferably
an x-ray linear accelerator. Such an x-ray beaming apparatus is
commercially available. The beaming apparatus may be activated by
the operator throwing a switch 23 at a control console 24 connected
to the beaming apparatus 20 by a cable 22.
[0021] The radiation treatment device 10 may also include an
apparatus for passing a first diagnostic beam 26 and a second
diagnostic beam 28 through the region previously imaged by the
three-dimensional image. The diagnostic beams are positioned at a
predetermined non-zero angle with respect to each other, such as
being orthogonal as shown in FIG. 2. The diagnostic beams may be
generated by a first x-ray generator 30 and a second x-ray
generator 32, respectively. A first and second image receiver 34,
36 or a single receiver may receive the diagnostic beams 26, 28 to
generate an image from the diagnostic beams which is fed into the
microprocessor 12 (as shown in FIG. 4) so that the diagnostic
images may be compared to the three-dimensional image.
[0022] The radiation treatment device 10 may also include a device
for adjusting the relative positions of the beaming apparatus 20
and/or the patient 14 so that the ionizing beam is continuously
focused on the target region 18. In the radiation treatment device
shown in FIG. 1, the positions of the beaming apparatus and the
patient may be altered with six degrees of freedom by a gantry 40
and a moveable operating table 38 with a tilting top 44. The
positions of the beaming apparatus relative to the patient may also
be accomplished by using a processor controllable robotic arm
mechanism that permits the beaming apparatus to be moved freely
about the patient's body including up, down, longitudinally along
or laterally along the body of the patient.
[0023] FIG. 3 is a block diagram of the radiation treatment device
10 including the microprocessor 12, the tape drive 13, the beaming
apparatus 20, the robotic arm 46 or the gantry 40, the x-ray
cameras 30, 32, 34 and 36, and the operator control console 24 as
described above. In addition, the device 10 may include safety
interlocks 50 to ensure that the beaming apparatus is not activated
accidentally. The device 10 may also include an operator display 48
for tracking the progress of the treatment and controlling the
treatment. Any further details of the radiosurgery device may be
found in U.S. Pat. No. 5,207,223 which is owned by the assignee of
this application and which is incorporated herein by reference.
[0024] The above system is well suited for the treatment of
stationary target regions (e.g., stationary with respect to bony
structures that can be seen on an image) wherein respiratory motion
or pulsation motion do not affect the accuracy of the treatment
beam. The drawback of the above system is that anatomic sites
subject to respiratory motion are difficult to treat. In accordance
with the invention, the frameless treatment system may improve upon
the system shown in FIGS. 1-3. The frameless treatment system and
method in accordance with the invention with the above advantages
will now be described.
[0025] FIG. 4 is a diagram illustrating a preferred embodiment of
the frameless treatment system 180 in accordance with the
invention. This embodiment of the invention is particular
applicable to the targeting of a target region without embedded
markers wherein there is no surrounding region that can be easily
located (e.g., no bones are present) and respiration motion may
affect the position of the target region. An example of a target
region for this embodiment is a lung tumor.
[0026] The treatment system 180 may include a patient treatment
table or couch 102 on which a patient 103 may rest during the
treatment. The treatment system may also include a diagnostic beam
recording device 104 that may be located underneath the treatment
table and underneath the patient and one or more diagnostic beam
generators 106 (one is shown in this example). The recording device
104 may record the images generated when the diagnostic beam device
is energized at one or more different predetermined positions. The
recording device 104 may be any device that can be used to capture
the image generated by the diagnostic beams. In a preferred
embodiment, the recording device 104 may be the amorphous silicon
plate that captures the x-ray beams being generated by the
diagnostic beam generators 106. The recording device 104 may be
connected to a computer that controls the operation of the
recording device and the diagnostic beam generator. The recording
device in this embodiment may also have a first portion 105 and a
second portion 107 wherein the first diagnostic beam is captured by
the first portion and the second diagnostic beam is captured by the
second portion. Thus, the diagnostic beams may be simultaneously
energized or may be sequentially energized. A recording medium with
one or more diagnostic beams is also shown in U.S. Pat. No.
5,207,223 to Adler which is owned by the same assignee as the
present invention.
[0027] The robot and the treatment beam generator (shown in FIG. 5)
are not shown in FIG. 4. The system may further include a track 152
in which the diagnostic beam generator moves so that the diagnostic
beam generator may be moved to different positions (see the
diagnostic beam generator 106 in a first position 154 and the other
positions shown by the phantom pictures of the generator) wherein
the diagnostic beam generator is at a different non-zero angle with
respect to the other positions. Thus, in this embodiment, the
diagnostic beam generator 106 is moved from the first position 154
to other positions at periodic times in order to generate the
images of the target region as described above. In addition to the
elements shown in FIG. 5, the system may also include a controller,
to position of the diagnostic beam generator, that may be
controlled by the computer.
[0028] In addition to the above, this system 180 may also include
an external marker tracking device 182 that may include one or more
external marker tracking generators 184 that generate one or more
external marker tracking beams 184, such as infrared beams or
passive markers whose position is detectable with optical cameras.
The system may also include one or more external markers 188
attached to the patient that measure the external movement of the
patient during respiratory motion as described in more detail in
the co-pending application that was incorporated by reference. Now,
the system will be described in more detail.
[0029] FIG. 5 is a block diagram illustrating more of the details
of the treatment system 100 of FIG. 4. In particular, the system
100 may include a computer 110 that controls the operation of the
various elements of the system including the beam generators 106,
108 as well as the image recorder 104. The system may also include
a treatment beam device 112, such as a linear accelerator (LINAC)
in this embodiment, that generates a treatment beam and a robot 114
that positions the treatment beam (a LINAC manipulator in this
embodiment) that are both controlled by the computer 110 that may
be a multi-processor computer in this embodiment. The computer may
issue control commands and receive back status commands from the
treatment beam generator 112, the robot 114 and the beam generators
106, 108. For the image recorder 104, the computer may issue
control signals to control the operation of the image recorder as
described above and may receive image data from the image
recorder.
[0030] The system may also include safety interlocks 116 that
ensures that the diagnostic beams and the treatment beam cannot be
activated (the beams are only energized when a status signal is
received by the computer) unless all people other than the patient
are out of the treatment room due to the radiation danger. The
system may also include a tape drive 118 for storing the images
generated by the image recorder, the pre-operative CT
three-dimensional images and any treatment planning software that
may perform the comparison of the images and control the movement
of the treatment beam. The system may further include an operator
control console 120 and an operator display 122 that permit a user
of the system, such as a surgeon, to interact with and operate the
system and monitor the treatment. The treatment planning software
in the computer may compare the pre-operative image to the images
from the diagnostic beam generators to determine how to control the
treatment robot and therefore the treatment beam during the
treatment. The computer, based on the comparison and the surgeon's
manual commands, may then control the treatment beam in order to
deliver the appropriate dose to the patient without damaging the
healthy tissue surrounding the target region. Now, a method of
treatment using the preferred embodiment will be described.
[0031] FIG. 6 is a flowchart illustrating a method 200 for
treatment in accordance with the invention using the system of FIG.
4. In step 202, a three-dimensional mapping of a region of the
patient including the target region is generated prior to the
treatment. The three-dimensional mapping may be done using typical
equipment such as computer tomography, magnetic resonance
tomography or the like. The three-dimensional mapping of the region
is stored in the storage device 118. The mapping shows the relative
locations of the target region with respect to other surrounding
regions that may be seen in the mapping to locate the target region
relative to the surrounding regions. For example, the target region
may be a lung tumor.
[0032] On the day of treatment, the patient may be positioned on
the treatment bed as shown in FIG. 9. The respiratory cycle of the
patient may then be determined in step 203 and at various different
times during the treatment. The respiratory cycle may be determined
by monitoring chest wall surface movement with optical or
ultrasound digitizers, and/or by using a strain gauge, by the
measurement of the airflow exiting the patient or by other well
known methods. In step 204, the system may determine if the
treatment can begin based on the status of the safety interlocks.
If it is not safe to begin the treatment, then the method loops
back to test the safety interlocks until a safe condition is
indicated.
[0033] In step 206, a diagnostic beam generator is positioned along
the track in the appropriate position and energized by the computer
in order to generate an image on the recording device. In a
preferred embodiment, the diagnostic beam generator is an x-ray
generators and the image recorder is an amorphous silicon imager
that generates an image in response to x-rays as is well known. The
image generated by the first diagnostic beam in the image recorder
may then be downloaded by the computer to the storage device
attached to the computer in step 208 and the image recorder may be
reset. Each image is acquired at the same phase of the respiratory
cycle 20 as described below with respect to FIGS. 7 and 8.
[0034] In step 210, the method determines if there are any other
positions for the diagnostic beam. If there are other positions for
the diagnostic beam, the method loops back to step 206 to energize
that generator at the other position, generate an image and
download the image to the storage device. In this embodiment, the
movement of the diagnostic beam generator along the track generates
multiple images wherein each image is at a non-zero angle with
respect to the other images and acquired during the same phase of
the respiratory cycle. In accordance with the invention, the method
sequentially energizes the diagnostic beam generator at different
positions to generate the images in a sequential manner. In
accordance with the invention, repeated sequence of images from the
diagnostic beam generator may be generated at periodic times so
that the location of the target region at different times may be
determined.
[0035] The series of diagnostic beam images may be processed using
a CT-like algorithm to generate a 3-D image of the patient during
the treatment. Once the series of diagnostic images are processed
into a 3-D image, the 3-D image is compared to the
three-dimensional pre-operative mapping as is well known to
determine the location of the target region at the particular time
in step 212. In step 214, the targeting of the treatment beam is
adjusted based on the comparison so that the treatment beam is
always focused on the target region. If there are repeated
diagnostic images generated, after each new set of images is
generated, the images are compared to the mapping and the treatment
beam targeting is adjusted to compensate for changes in the
position of the target region. In this manner, the target region is
accurately tracked so that the treatment beam is focused on the
target region.
[0036] In some cases, the placement of certain structures is
visible in the intra-treatment 3-D reconstruction, but the target
region or critical region is either not visible at all, not clearly
visible, or is visible but difficult to segment automatically by
computer. In this case, the system may comprise the step of
deforming the intra-treatment images in such a way that the
positions of the clearly visible structures best match the
pre-operative image data. From this, the exact deformation pattern
of the entire anatomical area can be inferred. The exact position
of the target and/or healthy critical tissue visible in the
pre-operative image data, but not clearly visible in the
intra-treatment data may be inferred as described in more detail
with reference to FIG. 13.
[0037] FIG. 7 is a chart 260 illustrating a typical respiration
cycle for a human being wherein the respiration cycle is
represented by a sine wave. The y-axis of the chart is the movement
of the chest wall thus showing that the chest wall moves out and in
during the respiration cycle. A first point 262 in the respiration
cycle with maximum expansion of the chest and a second point 264 in
the respiration cycle with no chest movement are shown. The
respiration cycle may be determined using the various techniques
described above. In accordance with the invention, the energizing
of the diagnostic beams and the treatment beam may be periodically
timed so that the energizing occurs at the corresponding points in
the respiration cycle such as at the first point or the second
point. In addition, the energizing of the beams may occur at more
than one time during the respiration cycle. Thus, the accuracy of
the treatment is improved since the beams are energized at the same
time in the respiration cycle.
[0038] FIG. 8 is a flowchart illustration of a method 270 for
energizing a diagnostic or treatment beam based on the respiration
cycle in accordance with the invention. In step 272, the treatment
is started and the respiration cycle of the patient is determined.
In step 274, the system determines if at predetermined point in the
respiration cycle has occurred and waits until the predetermined
point has occurred. Once the predetermined point in the respiration
cycle is reached, the system may energize the beam in step 276.
Now, a second embodiment of the invention will be described.
[0039] FIG. 9 is a diagram illustrating a second embodiment of the
frameless treatment system 150 in accordance with the invention.
This embodiment of the invention is particular applicable to
fiducial-less targeting of a target region wherein a surrounding
region can be located, but the surrounding region does not have a
fixed relationship with the target region (e.g., no bones are
present) and respiration motion does not affect the position of the
target region. An example of a target region for this embodiment is
the prostate.
[0040] The system 150 may include the same elements as the prior
embodiment as designated by like reference numerals such as the
treatment table 102, the image recorder 104 and the diagnostic beam
generator 106. As with the prior embodiment, the robot and the
treatment beam generator are not shown. In this embodiment, a
single diagnostic beam generator 106 may be used to further reduce
the cost of the treatment system. In this embodiment, the system
may further include a track 152 in which the diagnostic beam
generator moves so that the diagnostic beam generator may be moved
to different positions (see the diagnostic beam generator 106 in a
first position 154 and the other positions shown by the phantom
pictures of the generator) wherein the diagnostic beam generator is
at a different non-zero angle with respect to the other positions.
Thus, in this embodiment, the diagnostic beam generator 106 is
moved from the first position 154 to other positions at periodic
times in order to generate the images of the target region as
described above. The embodiment may have similar elements as those
shown in FIG. 5 and may also include a controller, to position the
diagnostic beam generator, that may be controlled by the computer.
Now, the method of treatment using the second embodiment will be
described.
[0041] FIG. 10 is a flowchart illustrating a method 160 for
treatment in accordance with the invention using the system of FIG.
9. In step 162, a three-dimensional mapping of a region of the
patient including the target region is generated prior to the
treatment. The three-dimensional mapping may be done using typical
equipment such as computer tomography or the like. The
three-dimensional mapping of the region is stored in the storage
device 118. The mapping shows the location of the target region
with respect to other surrounding regions that may be seen in the
mapping to locate the target region relative to the surrounding
regions. For example, the target region may be a prostate tumor and
the other surrounding regions may be the bladder. On the day of
treatment, the patient may be positioned on the treatment bed as
shown in FIG. 7. In step 164, the system may determine if the
treatment can begin based on the status of the safety interlocks.
If it is not safe to begin the treatment, then the method loops
back to test the safety interlocks until a safe condition is
indicated.
[0042] In step 166, a diagnostic beam generator is positioned along
the track in the appropriate position and energized by the computer
in order to generate an image on the recording device. In a
preferred embodiment, the diagnostic beam generators is an x-ray
generator and the image recorder is an amorphous silicon imager
that generates an image in response to x-rays as is well known. The
image generated by the first diagnostic beam in the image recorder
may then be downloaded by the computer to the storage device
attached to the computer in step 168 and the image recorder may be
reset. In step 170, the method determines if there are any other
positions for the diagnostic beam. If there are other positions for
the diagnostic beam, the method loops back to step 166 to energize
that generator at the other position, generate an image and
download the image to the storage device. In this embodiment, the
movement of the diagnostic beam generator along the track generates
multiple images wherein each image is at a non-zero angle with
respect to the other images. In accordance with the invention, the
method sequentially energizes the diagnostic beam generator at
different positions to generate the images in a time sequential
manner. In accordance with the invention, repeated sequence of
images from the diagnostic beam generator may be generated at
periodic times so that the location of the target region at
different times may be determined. The 2-D images generated by the
diagnostic beams are processed to yield a CT-like image which may
then be compared to the pre-operative 3-D mapping.
[0043] Once the diagnostic images are generated, the two or more
images are compared to the three-dimensional pre-operative mapping
as is well known to determine the location of the target region at
the particular time in step 172. The comparison may again include
the step of deformation as described above. In step 174, the
targeting of the treatment beam is adjusted based on the comparison
so that the treatment beam is always focused on the target region.
If there are repeated diagnostic images generated, after each new
set of images is generated, the images are compared to the mapping
and the treatment beam targeting is adjusted to compensate for
changes in the position of the target region. In this manner, the
target region is accurately tracked so that the treatment beam is
focused on the target region.
[0044] FIG. 11 is a diagram illustrating another embodiment of the
frameless treatment system 100 in accordance with the invention
that may be particularly suited for treating target regions that
have a fixed relationship to a fixed reference point, such as
bones. Thus, this embodiment of the invention may be used for
treating, for example, the spine of a patient or the brain of the
patient since these target regions are near or surrounded by bones.
The other embodiments of the invention described below may be
particularly suited for the treatment of other target regions. In
this figure, only one detector under the patient couch is used. The
two diagnostic beams in this case may either be activated
sequentially or the two beams may be activated simultaneously while
projecting their respective images to a different portion of the
single detector plate/camera. The simultaneous activation of the
diagnostic beams is particularly useful when time-stamps are needed
so that the exact time of a given 3-D position is known.
[0045] The treatment system 100 may include a patient treatment
table or couch 102 on which a patient 103 may rest during the
treatment. In the example shown, the brain of the patient is being
treated. The treatment system may also include a diagnostic beam
recording device 104 that may be located underneath the treatment
table and underneath the patient and one or more diagnostic beam
generators 106, 108 (two are shown in this example). The recording
device 104 may record the images generated when each diagnostic
beam device 106, 108 is energized. The recording device 104 may be
any device that can be used to capture the image generated by the
diagnostic beams. In a preferred embodiment, the recording device
104 may be the amorphous silicon plate that captures the x-ray
beams being generated by the diagnostic beam generators 106, 108.
The recording device 104 may be connected to a computer that
controls the operation of the recording device and the diagnostic
beam generators. The recording device in this embodiment may have a
first portion 105 and a second portion 107 wherein the first
diagnostic beam is captured by the first portion and the second
diagnostic beam is captured by the second portion. Thus, the
diagnostic beams may be simultaneously energized or may be
sequentially energized.
[0046] In accordance with the invention, the diagnostic beam
generators 106, 108 may be controlled by the computer to be
energized at different predetermined time intervals or
simultaneously so that each diagnostic beam generator is producing
an image on the recording device at a different time or
simultaneously. In addition, the diagnostic beam generators are
located at different positions so that the diagnostic beams pass
through the patient at different non-zero angles so that the angle
between the two diagnostic beams is also non-zero which permits a
two-dimensional image of the target region to be generated from the
two images.
[0047] In operation, the first diagnostic beam generator 106 may be
energized to emit a diagnostic beam that passes through the target
region and generates an image on the recording device. The image
developed by the recording device is then downloaded to the
computer and the recording device is erased. Next, the second
diagnostic beam 108 is energized and an image generated by the
second diagnostic beam is received by the recording device. This
image is also downloaded to the computer where it is stored with
the first image. By comparing these diagnostic images in
combination with the pre-operative 3-D CT scan or the like, the
treatment beam (not shown) of the treatment system may be
accurately targeted at the target region. For purposes of
illustration, the treatment beam generator and the treatment beam
robot are not shown in FIG. 11. The operation of this embodiment of
the treatment system is described in more detail below with
reference to FIG. 12.
[0048] FIG. 12 is a flowchart illustrating a method 130 for
treatment in accordance with the invention using the system of FIG.
11. In particular, in step 132, a three-dimensional mapping of a
region of the patient including the target region is generated
prior to the treatment. The three-dimensional mapping may be done
using typical equipment such as computer tomography or the like.
The three-dimensional mapping of the region is stored in the
storage device 118. The mapping shows the location of the target
region with respect to other surrounding regions that may be seen
in the mapping and appear on X-ray images made with the image
recorder. For example, the target region may be a brain tumor and
the other surrounding regions may be the skull bones. On the day of
treatment, the patient may be positioned on the treatment bed as
shown in FIG. 4. In step 134, the system may determine if the
treatment can begin based on the status of the safety interlocks.
If it is not safe to begin the treatment, then the method loops
back to test the safety interlocks until a safe condition is
indicated.
[0049] In step 136 when the treatment begins, a first diagnostic
beam generator is energized by the computer in order to generate an
image on the recording device. In a preferred embodiment, the
diagnostic beam generators are x-ray generators and the image
recorder is an amorphous silicon imager that generates an image in
response to x-rays as is well known. The image generated by the
first diagnostic beam in the image recorder may then be downloaded
by the computer to the storage device attached to the computer in
step 138 and the image recorder may be reset. In step 140, the
method determines if there are any other diagnostic beams to be
energized. If there are other diagnostic beams to energize, the
method loops back to step 136 to energize that generator, generate
an image and download the image to the storage device. In this
embodiment, there may be two diagnostic beam generators that are at
a predetermined non-zero angle with respect to each other. In
accordance with the invention, the method sequentially energizes
the diagnostic beam generators to generate the images from each of
the diagnostic beams in a time sequential manner. In accordance
with the invention, repeated pairs of images from the diagnostic
beam generators may be generated at periodic times so that the
location of the target region at different times may be
determined.
[0050] Once the diagnostic images are generated, the two images are
compared to the three-dimensional pre-operative mapping as is well
known to determine the location of the target region at the
particular time in step 142. In step 144, the targeting of the
treatment beam is adjusted based on the comparison so that the
treatment beam is always focused on the target region. If there are
repeated diagnostic images generated, after each new set of images
is generated, the images are compared to the mapping and the
treatment beam targeting is adjusted to compensate for changes in
the position of the target region. In this manner, the target
region is accurately tracked so that the treatment beam is focused
on the target region.
[0051] FIG. 13 illustrates a pre-operative image 250 and
intra-treatment image data 252 generated by the diagnostic beams.
As shown, the intra-treatment images generated by the diagnostic
beams are less clear and it is difficult to make out all of the
structures or even the target region in the image. The
pre-operative image 250, on the other hand, is very clear and each
structure of the body can be clearly seen. Therefore, in order to
make it possible to infer the position of the target region from
the intra-treatment images shown, the intra-treatment image is
deformed, using various well known deformation techniques such as
linear interpolation or warping, to form a deformed image 254 until
the intra-treatment images and its structures form the best match
with the pre-operative images. Once the deformation is completed,
the position of the target region may be inferred from the position
of the structures. This deformation technique may be used with all
of the embodiments of the invention described above.
[0052] Although the above embodiments show a single diagnostic beam
source being used, the invention is not limited to a single
diagnostic beam source. In fact, the system may use five fixed
sources that generate the diagnostic beams and two or more moving
sources that generate the diagnostic beams. For the fixed sources,
they may be activated at specific time points throughout the
respiration cycle. More detailed information about the deformation
model corresponding to respiratory motion may then be obtained as
set forth in the U.S. patent application Ser. No. 09/270,404.
[0053] While the foregoing has been with reference to particular
embodiments of the invention, it will be appreciated by those
skilled in the art that changes in these embodiments may be made
without departing from the principles and spirit of the invention,
the scope of which is defined by the appended claims.
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