U.S. patent number 3,777,124 [Application Number 05/093,332] was granted by the patent office on 1973-12-04 for computer assisted radiation therapy machine.
This patent grant is currently assigned to Varian Associates. Invention is credited to John M. Pavkovich.
United States Patent |
3,777,124 |
Pavkovich |
December 4, 1973 |
COMPUTER ASSISTED RADIATION THERAPY MACHINE
Abstract
A computer assisted radiation therapy machine is disclosed. The
machine includes a rotatable gantry having a radiation source
portion and a beam stopping portion. The gantry is rotatable about
a patient treatment couch which is rectilinearly translatable in
three orthogonal directions as well as being rotatable about the
vertical axis. Geometric and dose parameters defining a prescribed
treatment plan of radiation are stored in the memory of the
computer. Positional signals are derived from the various movable
controls and parts of the radiation machine. The prescribed
treatment parameters are compared with the actual positionings of
the elements and controls of the machine to derive an interlock
output when at least one of said actual parameters differs from the
respective prescribed parameter. The interlock output is employed
to inhibit application of radiation to the patient until the
mistake is rectified.
Inventors: |
Pavkovich; John M. (Palo Alto,
CA) |
Assignee: |
Varian Associates (Palo Alto,
CA)
|
Family
ID: |
27377478 |
Appl.
No.: |
05/093,332 |
Filed: |
November 27, 1970 |
Current U.S.
Class: |
600/1; 378/68;
378/117; 976/DIG.444; 700/84; 378/65; 378/91; 378/97; 378/196 |
Current CPC
Class: |
G05B
19/188 (20130101); A61B 6/4476 (20130101); G21K
5/10 (20130101); G05B 19/40935 (20130101); A61B
6/4441 (20130101); A61N 5/01 (20130101); A61N
5/10 (20130101); A61B 6/102 (20130101); H05G
1/44 (20130101); G05B 2219/34376 (20130101); G05B
2219/36551 (20130101); G05B 2219/34242 (20130101); G05B
2219/42256 (20130101); A61N 2005/1074 (20130101); G05B
2219/45169 (20130101); G05B 2219/35307 (20130101); G05B
2219/36153 (20130101); G05B 2219/35285 (20130101); G05B
2219/42205 (20130101); G05B 2219/49143 (20130101); G05B
2219/36087 (20130101) |
Current International
Class: |
A61B
6/10 (20060101); A61B 6/00 (20060101); G21K
5/10 (20060101); A61N 5/01 (20060101); A61N
5/10 (20060101); G05B 19/18 (20060101); H05G
1/44 (20060101); H05G 1/00 (20060101); G06f
015/42 (); A61n 005/00 () |
Field of
Search: |
;235/151,61.6H
;250/61.5 |
Foreign Patent Documents
Primary Examiner: Botz; Eugene G.
Claims
What is claimed is:
1. In a radiation therapy apparatus, couch means for supporting a
patient to receive radiation, radiation source means for applying
radiation to the patient, means for supporting and moving said
radiation source means about said couch means, means for
establishing outputs corresponding to prescribed positions of said
source means and said couch to define a prescribed treatment plan
of radiation for the patient, means for generating positional
outputs representative of the actual positions of said couch and
radiation source means, means for comparing the prescribed
positional outputs of said radiation source means and said couch
means with actual positional outputs of said radiation source and
couch means to derive an interlock output when at least one of such
actual positional outputs differs from the respective prescribed
positional output, interlock means responsive to the interlock
output for inhibiting application of radiation to the patient,
whereby treatment mistakes are minimized.
2. The apparatus of claim 1 wherein said means for comparing the
prescribed positional outputs of said radiation source and couch
means with the actual positional outputs thereof, to derive an
interlock, includes, a programmed general purpose computer.
3. The apparatus of claim 1 including, display means for displaying
to an operator the prescribed positions of said radiation source
and couch means and the actual positions of said radiation source
means and said couch means.
4. The apparatus of claim 1 wherein said means for establishing the
prescribed positional output of said radiation source and said
couch means includes, information storage means for storing a
prescribed treatment plan which includes information defining the
prescribed positions of said radiation source means and said couch
means, and means for reading the prescribed positional definitions
from said information storage means.
5. The apparatus of claim 4 wherein said information storage means
includes, a storage tape, and wherein said information reading
means includes, a tape reading means.
6. The apparatus of claim 4 including general purpose computer
means having a memory, said information storage means including
first storage means for storing the treatment plan of prescribed
positional information of said radiation source and couch means for
each given patient, said computer means being programmed to
transfer the prescribed positional information from said first
storage means into said memory of said computer means, and said
computer being programmed to read the prescribed definitions from
said memory of said computer to establish the prescribed positional
outputs of said radiation source means and said couch means.
7. In a radiation therapy apparatus, couch means for supporting a
patient to receive radiation, radiation source means for applying
radiation to the patient, means for supporting and causing relative
movement between said radiation source means and said couch means,
means for establishing outputs corresponding to prescribed relative
positioning of said source means and said couch means to define a
prescribed treatment plan of radiation for the patient, means for
generating positional outputs representative of the actual relative
positioning of said couch means and radiation source means, means
for comparing the prescribed positional outputs of the relative
positioning of said radiation source means and said couch means
with actual positional outputs of the relative positioning of said
radiation source and couch means to derive an interlock output when
at least one of such actual positional outputs differs from the
respective prescribed positional output, and interlock means
responsive to the interlock output for inhibiting application of
radiation to the patient, whereby treatment mistakes are
minimized.
8. The apparatus of claim 7 in which said means for causing
relative movement between said radiation source means and said
couch means includes means for moving each of said couch means and
radiation source means relative to the other, said means for
comparing said prescribed and actual positional outputs comprises a
computer programmed to derive error signals representative of
difference between said prescribed and actual positions and to feed
said signals to said means for moving said couch means and
radiation source means, whereby said actual relative positioning is
automatically caused to coincide with said prescribed relative
positioning.
Description
DESCRIPTION OF THE PRIOR ART
Heretofore, the mechanical setup of a radiation therapy machine has
been automated for decreasing the setup time and improving the
accuracy of the mechanical setup for a radiation therapy treatment.
In the prior machine, the desired positional information for the
mechanical setup of the machine was punched into cards according to
a prescribed plan of treatment. A deck of cards representing the
setup for the prescribed plan of treatment was fed into a card
reader. The output of the card reader was fed to control circuits
for sequentially controlling the mechanical motions of various
movable parts of the machine for geometrically positioning the
gantry and treatment couch according to the prescribed plan of
treatment. A four digit visual display was provided for displaying
the position of each of the mechanically movable elements of the
radiation therapy machine.
While the aforecited automated radiation therapy machine
substantially decreased the setup time and improved the accuracy of
the setup, it still leaves room for operator error or machine
error, as the operator must compare the readout positions of the
various movable elements against a treatment plan to see that each
of the elements is in the desired position. In addition, the
operator must set the treatment time for the radiation dose
according to the treatment plan, thereby introducing further chance
of error.
It is desired to obtain an improved automated radiation therapy
machine which automatically checks the geometric and control setup
of the radiation therapy machine against a prescribed treatment
plan to render an output indicative of a discrepancy therebetween,
whereby operator errors are minimized.
SUMMARY OF THE PRESENT INVENTION
The principal object of the present invention is the provision of
an improved automated radiation therapy machine.
One feature of the present invention is the provision of means for
automatically checking the setup of the radiation machine against a
prescribed plan of treatment and noting any discrepancies
therebetween and initiating an interlock output which inhibits
application of radiation to the patient until the discrepancy
between the treatment plan and the actual settings of the machine
have been eliminated, whereby treatment mistakes are minimized.
Another feature of the present invention is the same as the
preceding feature wherein the means for automatically comparing the
treatment plan against the actual settings of the machine comprises
a programmed general purpose computer.
In another feature of the present invention, display means are
provided for displaying to the operator the prescribed treatment
plan and the actual settings of the radiation machine such that the
operator is readily apprised of any discrepancies therebetween.
In another feature of the present invention, the prescribed
settings for the radiation therapy machine are recorded on storage
means, such as magnetic tape, disc or paper tape, and the machine
includes means for reading the prescribed settings of the machine
from the storage.
In another feature of the present invention, the prescribed
settings of the machine for administering a certain treatment are
read from a treatment storage means and fed into the memory of the
computer. The computer is programmed to read the prescribed machine
settings from its memory for comparison with the actual settings of
the machine.
Other features and advantages of the present invention will become
apparent upon perusal of the following specification taken in
connection with the accompanying drawings, wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram, partly in block diagram form, of an
automated radiation therapy machine incorporating features of the
present invention,
FIG. 2 is a schematic circuit diagram for deriving signals
determinative of the settings of the respective variable parameters
of the radiation therapy machine, and
FIGS. 3a and 3b are a computer program flow chart for the computer
assisted radiation therapy machine of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, there is shown a computer controlled
radiation therapy machine incorporating features of the present
invention. The radiation machine 1, such as a CLINAC.sup.R
radiation therapy machine model 4 or 35, commercially available
from Varian Associates, or a THERATRON 80 automated cobalt 60
radiation machine made by Atomic Energy of Canada Limited of
Ottawa, Canada, includes a couch 2 having a table portion 3 which
receives the patient to be treated. The couch 2 is rotatable about
a vertical axis 4 by means of a turntable 5 which the couch 2 is
affixed. The couch includes an elevator portion 6 for translating
the couch in the vertical direction Z. In addition, the couch
includes motorized drives for translating the table 3 in the
lateral Y direction and longitudinal X direction. A control pendant
10 is connected to the couch 2 via suitable cable for manual
control of the various portions of the radiation machine 1 and for
allowing automatic control of the radiation machine 1 by the
computer.
A generally C-shaped gantry 8 is rotatable by 359.degree. about a
horizontal axis 9. The gantry 9 is rotatably supported from a stand
11. A source of radiation, such as a linear accelerator producing a
high energy electron beam which is directed against an X-ray
target, produces a beam of X-rays emanating from a collimator head
portion 12. As an alternative, in the case of the cobalt machine,
the cobalt serves as a source of X-ray radiation, and is housed
within the collimator head portion 12. The X-rays are directed out
of the radiating head portion 12 in a beam having an axis 13 which
intersects the gantry axis of rotation 9 at a position identified
as the isocenter 14, which is also intersected by the turntable
axis 4.
The head portion 12 includes two sets of movable beam defining
jaws, as of lead, which are movable to define the length L and
thickness T of the field of the X-ray beam as collimated by the
beam defining jaws. The source 12 is enclosed in a barrel shaped
collimator housing 15. The source housing 15, along with beam
defining jaws, are rotatable about the beam axis 13. The gantry 8
includes a beam stopping portion 16 disposed along the X-ray beam
axis 13 and holding an X-ray absorbing material, such as lead, for
stopping and absorbing the X-ray beam.
A digital computer 18, such as a Varian Data Machine Model 620/i
general purpose digital computer, is coupled to the radiation
therapy machine 1 via the intermediary of a control cable 19 and an
interface 21. The computer 18 includes a core memory portion 22
interconnected to a central processor 23 which includes the address
and arithmetic units. 16 channels of analog-to-digital converters
24 are provided for converting analog output signals derived from
the radiation therapy machine 1 to digital form which are in-turn
fed into the central processor 23 for use therein and for use in
the memory 22. Eight channels of digital-to-analog converters 25
are provided for converting digital output signals from the central
processor 23 into analog signals which in-turn are fed into the
radiation therapy machine 1 via the intermediary of the interface
21. Sensor and control lines 26 are provided for sensing and
controlling functions of the radiation therapy machine via the
interface 21. A machine console 27 is coupled to the radiation
therapy machine 1 and to the computer 18 via the machine interface
21.
The Varian data machines 620/i computer 18 is a system oriented
digital computer. It has a total memory capacity of 12,388 words of
16 or 18 bits and is plug-in expandable. The memory is magnetic
core with 1.8 microseconds full cycle and 700 nanoseconds access
time. The arithmetic is parallel, binary, fixed points, 2's
complement. It has seven addressing modes and over 100 standard
instructions. In addition, to the standard equipment which comes
with the Varian 620/i computer, the computer 18 includes, a 620/i
expansion chassis, two 620/i memory modules providing an extra
8,192 words, a 620/i-17 optional package, a 620/i-51 paper tape
reader, an acquisition and control unit, and the 620/i machine
interface 21.
The 620/i-17 optional package contains hardware multiply/divide,
extended addressing, real time clock, power fail/restart, and eight
level priority interrupts. The 620/i-51 accessory is a high speed
paper tape reader which provides for rapid means to load the memory
should a program be lost or scrambled for some reason. It is an
input device only and will not punch. It reads at 300 characters
per second. The acquisition and control unit contains the
following: 7 or 12 bits plus sign programmable sample-and-hold, 16
channels or multiplexed analog-to-digital conversion 24, and the 8
channels of 9 bit plus sign digital-to-analog converters 25 plus 16
sense and 8 control lines 26. In addition, the acquisition and
control unit contains the BCD registers and controller for the BCD
information available from the radiation machine 1.
A digital cassette tape unit 28, such as a model 100 COMPUCORDER
available from Datatronics, Inc. of Rochester, N.Y., is coupled by
suitable cables to the central processor 23 for reading digital
data, stored in the patient's individual cassette, into the central
processor 23 and memory 22. In addition, outputs from the processor
23 are recorded back into the patient's cassette via the tape unit
28. A cathode ray tube/keyboard terminal 29, such as a model ALPHA
103A CRT/ keyboard terminal, commercially available from Beehive
Medical Electronics, Inc. of Salt Lake City, is coupled to the
central processor 23 via cable 31 for displaying data read from the
memory 22 through the central processor 23 and for controlling
certain operations of the radiation therapy machine 1 via the
computer 18.
The CRT terminal 29 forms the major input-output device for the
computer 18 and includes an alpha numeric display. It has a
standard typewriter keyboard and four-way cursor control. In
addition, it has an 11 inches CRT screen with 20 lines and 40
characters per line. The CRT terminal 29 has type-over capability
using the cursor as well as line-erase and screen-clear. It has its
own internal character generator with 64 characters ASC II set. A
remote slave cathode ray tube (CRT) 32 is provided for remote data
observation. A standard ASR 33 teletype unit is coupled to the
central processor 23 via suitable cables to provide a hard copy
printout and to serve as a backup input for the CRT/keyboard
terminal 29 and for the paper tape reader accessory of the computer
18.
Referring now to FIG. 2 there is shown one of the circuits for
generating an analog positional signal determinative of the
position of one of the variable parameters of the radiation machine
1, such as: gantry angle G; housing angle, H; couch position in the
X, Y and Z directions, etc. The positional signal circuit of FIG. 2
includes a potentiometer 34, as of 10 k ohms, attached to the drive
shaft 35 via mechanical coupling 36. Drive shaft 34 generates the
motion of the parameter being controlled, such that a full-scale
motion of the parameter being varied or controlled results in
generating a full scale +10 volts to -10 volts analog output
deprived from the pickoff 37 of the potentiometer 34. -15 volts and
+15 volts, respectively, are applied to opposite ends of the
potentiometer 34 through trimming potentiometers 38 and 39 provided
at the ends of the potentiometer 34. The trimming potentiometers 38
and 39 provide for calibration of the range and the end points for
each positional output readout. One turn 0.25 percent linearity,
0.095 percent resolution potentiometers 34 are utilized on the beam
collimator jaws, and position indicators. Ten turn 0.1 percent
linearity, 0.019 percent resolution potentiometers 34 are provided
for each of the other analog positional readouts.
Each of the motorized control motions of the radiation machine 1 is
driven by a shunt-wound dc motor 40 operated by an SCR controller
41. With exception of the gantry rotation controller, each
controller is open-loop providing full output in response to a
6-volt dc signal, decreasing to 0 output at 0.5 volts dc (.+-.0.5
dead band volts). The gantry speed control is closed loop, speed
regulated, full speed output in response to a 12-volt dc input,
against with .+-.0.5 dead band volts. The turntable drive is
equipped with a brake which is engaged when the input voltage of
the motor controller is zero. The couch longitudinal and lateral
motions have switch actuated electric clutches engaging their
respective drives.
Control of each motion of the radiation therapy machine 1 is
obtained by direct digital control. Positions of each of the eight
analog motions are sampled, by sampling the output of each
potentiometer 34, every 50 milliseconds, 10 microseconds required
for each sample. Sampling is controlled by the central processor 23
and is effected through the interface 21 to the positional control
circuits of FIGS. 2 coupled to the drive 35 for each of the driven
elements of the radiation therapy machine 1. The driven motions are
sufficiently fast so as to alter their feedback from zero to full
scale in 15 seconds. Assuming a 12-bit plus sign analog-to-digital
converter output will vary a maximum of one least-signifant bit in
3.6 milliseconds, allowing observation of at most four
least-significant bit changes at every reading.
Each patient has in his file a digital type cassette. For treatment
of a patient, his cassette is loaded into the tape unit 28 and a
command from the keyboard terminal 29 causes the tape to be read
into the central processor 23 and stored in the memory 22 of the
computer 18. The information transferred from the cassette to the
memory 22 of the computer 18 includes the patients identification
number, his name, the diagnosis of his condition, the portal
definition of eight separate radiation treatment portals, each
including an identification number 1-8 and a definition of the
quantities, G, S, X, Y, Z, H, L, T, and dose for each of the
defined portals, whether the individual treatment will involve arc
therapy, and if so the start and stop gantry angles G, and the rads
per degree, and information as to which, if any wedge is to be
employed and whether blocks are to be employed. Wedges serve to
shape the intensity of the radiation beam, and blocks serve to
protect certain portions of the patient being treated for radiation
emanating from the beam. In addition, information stored in the
memory 22 from the patient's cassette, includes a sequence of how
the portal definitions are to be administered, i.e., the treatment
plan, the monitored cumulative dose per portal, and the total
cumulative dose for the patient.
Once this information has been stored in the computer 18, the
keyboard terminal 29 is actuated for displaying desired information
from the memory 22 on the display of the keyboard terminal 29. On a
proper command from the keyboard terminal 29, the central processor
23 causes to be displayed, from the memory 22, on the cathode ray
tube display 29, the next treatment to be given. For example, a
certain radiation portal is defined on the visual alphanumeric CRT
display, with the prescribed set points for the quantities of
G,S,X,Y,Z,H,L,T, etc. Opposite the prescribed values for the
aforementioned quantities, which define the treatment to be given,
is displayed the corresponding present position of each of the
settings of the radiation therapy machine 1. Positional values are
obtained from the output of the positional circuits of the type
shown in FIG. 2 as converted to digital form via the
analog-to-digital converters 24 and as sent to the display tube of
the keyboard terminal 29, from the central processor 23. Upon
depressing the proper command button on the machine control pendant
10, the central processor 23 causes the actual positional signal to
be monitored and to be compared with the prescribed positional
signal to derive error signals which are fed to the controllers for
causing the radiation therapy machine 1 to take the positions
defined by the treatment plan being executed.
An anti-collision program is stored in the memory 22 and the
central processor, in conformance with the program, continually
checks for the possibility of a collision between the gantry 8 and
the couch 2. If imminent collision is determinted, an
anti-collision sub-routine is executed to avert the collision. The
radiation machine is positioned in accordance with the
predetermined prescribed plan. The geometric set points can be
achieved in less than 30 seconds because all of the geometric
motions of the radiation machine are obtained simultaneously.
As each of the geometric parameters achieves its set point, the set
point value is displayed on the cathode ray tube opposite the
corresponding prescribed value for the treatment plan being
executed. Thus, all the set point values for the quantities G, S,
X, Y, Z, H, L, and T are achieved automatically and presented
automatically. The planned values for dose, time, rads per degree,
stop angle, wedge and blocks are displayed but these adjustments
are made manually from the machine console 27. Each of the manual
adjustments from the machine console 27 has a BCD positional output
signal generator of conventional design coupled thereto in the
conventional manner. As the manually adjustable parameters are set,
the corresponding positional value is fed into the computer 18 and
presented on the display adjacent the planned value. Each wedge and
block is separately coded with electrical connections and
electrical connections are made to these coded connections for
feeding an input signal to the computer 18 corresponding to the
particular wedge or block employed. Thus wedge and block
information is also fed to the computer and presented on the
display 29.
The computer 18 is programmed to compare the prescribed value for
all of the aforementioned geometric and other machine parameters
against the set point values achieved for each of the adjustable
parameters. If all of the prescribed values do not conform to the
set point values, the computer 18 generates an interlock output
signal which is fed via the machine interface 21 to actuate a relay
45 which opens a circuit in the machine console 27 and prevents
energization of the radiation ON button 46 in the machine console
27 such that the beam of radiation cannot be turned onto the
patient until all of the actual set point values for the variable
parameters of the radiation machine conform to the prescribed
values. This greatly reduces the probability of the operator making
a mistake and delivering a dose of radiation to the patient which
is not called for by the prescribed treatment plan. Tolerances in
the mechanical settings can be built into the system to compensate
for uncertainties in patient positioning on the treatment couch
2.
Throughout the treatment, the computer 18 monitors the radiation
machine parameters and gives constant feedback to the therapist and
technologist. After treatment, the patient status information on
the cassette is updated by updating the patient treatment plan in
the memory 22 and transferring the updated information from the
memory 22 of the computer 18 to the patient's cassette. A hard copy
printout of the administered treatment details is readout of the
updated memory and typed by the teletype 33.
Any detail of the prescribed overall radiation treatment plan or
any one of the prescribed parameters of an individual portal
descriptions can be easily changed during the course of treatments.
The operator pushes an EDIT button on the CRT keyboard terminal 29
and types in the appropriate change at the keyboard. Two levels of
edit capability are incorporated. Certain major changes, such as
overall treatment plan, can only be initiated by supervisory
personnel with a special access key which serves to complete an
interlock circuit in an interface between the CRT/keyboard terminal
29 and the central processor 23. If the therapist desires periodic
examination before certain treatments can be administered to the
patient, he can require that some one of supervisory rank be
present at a given treatment by typing in an appropriate legend in
the overall treatment plan.
The radiation head portion 12 of the radiation therapy machine 1
includes a dosimeter for monitoring the dose of radiation as given.
The output from the dosimeter is employed for measuring the dose
given and for updating the cumulative total of radiation given at
each radiation portal and the total cumulative radiation given for
all portals. This update information is transferred from the
computer to the patient's cassette upon termination of each
treatment. In this manner, all the information for an updated
treatment plan is recorded in the patient's individual cassette. A
computer program flow chart for the aforedescribed computer program
is shown in FIGS. 3a and 3b.
Since many changes could be made in the above construction and many
apparently widely different embodiments of this invention could be
made wihout departing from the scope thereof, it is intended that
all matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
RELATED CASES
The simultaneous motion and anti-collision program are described
and claimed in copending U.S. application Ser. No. 93,327 filed
Nov. 27, 1970, the feature of editing and updating the treatment
plan is disclosed and claimed in copending U.S. application Ser.
No. 93,331 filed Nov. 27, 1970, both applications are assigned to
the same assignee as the present invention.
* * * * *