JPH0357466A - Control method for positioning device for radiation therapy plan - Google Patents

Abstract

PURPOSE:To execute the control of an arm module being free from misalignment of the left and the right marks by allowing the other arm module to follow one arm module and operating it, and allowing it to execute a position calculation by a table stored in a muPU. CONSTITUTION:Each arm module 7S, 7L and 7R on which center, left and right side face pointers 1, 2L and 2R are placed, respectively is moved at every unit, and data of a relation of a position of the arm module and a mark projected position is stored in a muPU 10. At the time of positioning a projected position of a mark in an arbitrary position by the left and the right side face pointers, the arm module 7R of one side face is moved by a point moving motor 5R and stopped in a prescribed mark projected position by visual observation, and based on the data, the mark projected position is derived by a calculation, and by calculating a position of the other arm module 7L from the mark projected position, the feed quantity of a necessary arm module is calculated, a driving signal pointer of the number of pulses obtained therefrom is sent to a moving motor 5L, and positioning of the other arm module is executed.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method of controlling a positioning device for radiation therapy planning for various high-energy radiation treatments, and in particular, when projecting marks at arbitrary positions, The present invention relates to a method of controlling a positioning device for radiation therapy planning to match.

(Prior art) Since the appearance of linear accelerators for cancer treatment,
Various radiotherapy devices have appeared, and Rl (Radiotherapy) using gamma rays emitted from radioactive isotopes such as cobalt-60 has appeared.
Treatment devices using high-energy radiation, such as isotope therapy devices, electron beam/X-ray therapy devices, fast neutron therapy devices, and heavy ion particle therapy devices, have been successively developed and come into use. With the development of high-energy radiation therapy with remarkable therapeutic effects, more emphasis has been placed on highly accurate treatment planning. For this reason, radiation therapy equipment has been devised and developed to be able to respond to higher precision treatments, and at the same time, technology has progressed rapidly in terms of actual treatment planning and application, and the importance of treatment planning has become even more recognized. It became so.

The overall picture of the treatment system can be considered as follows.

The first stage is diagnosis, in which the location, size, shape, etc. of the affected area are accurately determined. The second step is treatment planning, in which the application to the patient, such as the treatment radiation type, single dose irradiation direction, etc., is comprehensively defined based on the various information obtained at the time of diagnosis.

The third step is to apply the treatment, locating, confirming, and irradiating the radiation field to the patient. Fourth
The stage is the management stage, in which data from each stage of diagnosis, treatment, and application are collated, recorded, and stored for use in treatment planning and as a reference after treatment is completed.

There is a strong demand for a highly accurate treatment planning device that can accommodate these four stages as an indispensable tool, one of which is a positioning device for radiation therapy planning.

This radiation therapy meter dual-use positioning device determines the location of the affected area to be treated with radiation therapy using X-ray CT, etc., and projects a cross mark using a laser beam from the top and sides of the subject's body surface to begin radiation therapy. It is a device for positioning on the body surface when performing a laser beam, and is usually referred to as a laser beam force. Hereinafter, the positioning device for radiation therapy planning will be abbreviated as a marker.

This marker projects a laser beam from the upper and side surfaces of a subject who is lying on their back or side, to determine the position on the body surface of the affected area, and to appropriately grasp the irradiation position and irradiation field during radiotherapy. This is the device. Therefore, the marker has a pointer that projects a cross mark of laser light onto the body surface of the subject, and the pointer is mounted on an arm module and is configured to be moved horizontally or vertically by a step motor. Positioning is performed by projecting a cross mark using a laser beam from a pointer at the position where the radiotherapy treatment of the subject is to be performed, which has been calculated by the workstation. FIG. 5 is a diagram showing the arrangement of the pointer and the driving section of the marker mentioned above. In the figure, 1 is
A central pointer 2L is installed on the ceiling of the X-ray CT imaging room to project a cross mark onto the upper surface of the patient. The left side pointer 2R is the right side pointer attached to the right wall surface. The center pointer 1 is placed on an arm module (not shown), and the arm module is moved left and right by a center pointer moving motor 3 to be positioned. 4 is provided at the end of the moving rail, and 5L is a center pointer position sensor which is a glue switch to limit the amount of movement of the center pointer 1 that would cause it to come off the rail when moving from side to side; 5L and 5R are left side pointer 2L, A left side pointer movement motor and a right side pointer movement motor are used to vertically move and position the arm module (not shown) on which the right side pointer 2R is mounted, and the left ffll1 surface pointer position sensor 6L and the right ffllJ surface pointer position sensor are used. 6R prevents the limit position from being exceeded.

(Problem to be Solved by the Invention) By the way, the left side pointer 2L and the right side pointer 2R must face the subject and project the cross mark at the same position, but each pointer 2L, 2R must There is a distance of 2 m or more from the pointer to the subject's body surface, and the cross marks made by the left and right pointers often do not match due to distortion of the pointer feeding mechanism. This state is shown in FIG. The figure shows a left side pointer 2L as an example. This example shows a case where when the left side pointer 2L is moved upward by 200 mm, the cross mark on the object projection plane is moved by 203 mm due to the distortion of the feed mechanism. A similar thing occurs with the right side pointer 2R, and as a result, the projections of the cross marks from the left and right pointers 2L and 2R do not match.

By the way, when attempting to mark the affected area using X-ray CT to determine the location of the affected area to be treated with radiation as described above, for example, the location may be inappropriate for marking because it hits the top of the eyeball and the eyelid moves, or the location is inappropriate for the marking location. If it is not possible to mark the hole at the same position, it may be necessary to mark at a different position, such as moving the hole by 20 mm from that position to a position that is easier to mark, regardless of the position calculated by the workstation. . In this case, positioning is different from the case where it is determined by calculation using a work station, and the position control is performed manually by turning on and off the switch for commanding the movement motor operation, which is different from the case of automatic control. necessitates a different control method.

The present invention has been made in view of the above points, and its purpose is to:
An object of the present invention is to realize a control method for a positioning device for radiation therapy planning, in which a cross mark is set at an arbitrary position using one of the left and right pointers, and the projection position of the other cross mark is accurately matched.

(Means for Solving the Problems) The present invention solves the above-mentioned problems by using a central arm module mounted on an arm module provided on the upper and left and right walls for projecting a mark with light onto the body surface of a subject for radiation therapy. , a control method for a radiation therapy positioning apparatus having left and right side pointers, and center and left and right side pointer movement motors for moving the arm module, the position of the center and left and right side pointers by unit movement of the arm module and the position thereof; Measure the position of the corresponding mark and use the data as μP.
A step of storing the arm module in the U, a step of moving the arm module on one side by raising or lowering and setting a mark on the side at a desired position, and a step of moving the arm module on the other side slightly into the arm module. a step of performing a follow-up movement with a delay; a step of calculating the position of the mark on the one side from the position of the arm module based on the data stored in the μPU; and a step of calculating the position of the mark on the one side from the position of the mark determined by the calculation. calculating the feed amount from the current position of the other arm module based on the data stored in the μPU; and sending a pulse to the left or right side pointer movement motor from the feed amount of the other arm module. The present invention is characterized by comprising the steps of calculating a number, and sending a signal of the number of pulses obtained by the calculation to the left or right side pointer movement motor.

(Operation) Each arm module carrying the center, left and right side pointers is moved unit by unit, and data regarding the relationship between the position of the arm module and the mark projection position is stored in the μPU. When positioning the mark projection position to an arbitrary position using the left and right side pointers, move the arm module on either side and visually stop it at a predetermined mark projection position, and then set the mark projection position based on the above data. Calculate the position of the other arm module from the mark projection position to calculate the required feed amount of the arm module, and then send a drive signal of the obtained number of pulses to position the other arm module. conduct.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a marker used to execute a control method according to an embodiment of the present invention. In the figure, the same parts as in FIG. 5 are given the same reference numerals. In the figure, 7S is an arm module to which the center pointer 1 is attached, and is used to move the center pointer 1 to the left and right of the figure and project a cross mark onto the upper body surface of the affected area of the subject, and 7L and 7R are arm modules, respectively. This is an arm module to which left and right side pointers 2L and 2R are attached, and for moving each pointer 2L and 2R up and down. Each arm module 7S, 7L, 7R has a central pointer moving motor 3 which is a step motor.
, a left side pointer movement motor 5L and a right side pointer movement motor 5R, and the position of each arm module, that is, the position of each pointer 1.2L, 2H, is determined by an encoder directly connected to the motor shaft of each movement motor 3, 5L, 5R. detected by. 8 is arm module 7S, 7L
, 7R, and turn on and off the laser tubes of each pointer.The manual information is converted into infrared rays, detected by a photodetector, and input manually to the microcomputer (hereinafter referred to as μPU) 10. μPUIO
controls the turning on and off of the laser tube and the movement motors for moving the arm module based on the above-mentioned human power. Reference numeral 11 denotes a CRT that displays position information of the arm modules 7S, 7L, and 7R and the on/off state of the laser tubes. The interior light 12 is μP U1. When the relay laser tube is turned on, it is turned off to make the cross mark clearer, under the control of O.
This is an indoor light that is turned on when the laser tube is turned off. Reference numeral 13 denotes a workstation that calculates and determines the position for performing post-radiation therapy on the subject.

Next, the operation of the apparatus configured as described above will be explained, and then a control method for making the cross marks coincide will be explained. X
The affected area is identified by tomography or X-ray fluoroscopy along lines C and T (not shown), and markings are made on the identified affected area for therapeutic radiation irradiation from the body surface. The hand controller 8 manually inputs the position of the arm module of each pointer to the μPU 10. μPUIO controls the center pointer movement motor 3, the left side pointer movement motor 5L, and the I side pointer movement motor 5R, and controls the arm module 7S of the center pointer 1, the arm module 7L of the left side pointer 2L, and the arm of the right side pointer 2R. The module 7R is moved, and a cross mark for positioning the affected area to be irradiated with radiation from the body surface is moved from the center pointer 1, left side pointer 2L, and right side pointer 2R to the upper part of the body surface. Projection is performed using laser beams on the left and right sides. The position of each pointer is detected by an encoder directly connected to each moving motor shaft and displayed on the CRT 11. The center pointer position sensor 4, left side position sensor 6L, and right side pointer position sensor 6R are respectively connected to the center pointer 1. Starting point of left side pointer 2L and right side pointer 2R. When it reaches the end position, it is detected and input to μPUIO. Next, the hand controller 8 is used to manually turn on the laser tubes of each pointer, and a cross mark is projected onto the body surface of the subject. The lighting condition of this laser tube is also CRTI
It is displayed on I. The interior light 12 is turned off when the laser tube is turned on, that is, when the cross mark is projected.

Next, a control method for matching the cross marks on the body surface from the left side pointer 2L and the right side pointer 2R will be explained. Consider the case where the left side pointer 2L is moved in the positioning operation.

The arm module 7L is moved by 20 mm and the position error of the cross mark on the projection plane is measured.

A graph of this position error is shown in FIG. The positional error information on the projection plane obtained in this manner is stored in μPUIO, for example, as a table of the relationship between the pointer position and the cross mark position.

In the implementation stage of moving the arm module 7L to correctly project the cross mark, μPUIO controls the arm module 7L in the manner described below. A graph of the relationship between the position of the arm module 7L and the position of the cross mark on the projection plane is shown in FIG. In this graph, the data actually measured and stored in μPUIO are points B and D, and the position of the cross mark on the projection plane of point B of 20 mm is 19 mm, and the position of the cross mark on the projection plane of point D of 40 mm. is 43 mm. When moving from point A to point C, calculate the moving distance as follows.

(1) First, the movement ia is determined using the positional information of the origin and point B stored before and after the target position to be moved.

(2) Next, determine the amount of movement b based on the position information of points B and D.

(3) The amount of movement p of the arm module 7L required to move from point A to point C is p=1+b·18. 64 (4) If α is the number of pulses sent to the left side pointer movement motor 5L in order to move the arm module 7L by 1 mm, then 18.64α pulses should be sent.

By doing the above, the cross mark can be projected onto the subject with sufficient accuracy for practical use.

The above is a normal operation for marking, but if it is not possible to mark directly at the radiation irradiation position, marking is performed at a position shifted by an appropriate amount from the position to be marked. The procedure is to turn on the operation command switch of the μPU 10 for operating the left and right side pointer movement motors 5R and 5L. The right side pointer movement motor 5R is μP U1.
Rotation is started by a drive pulse from 0, and arm module 7R begins to move. After a short delay, the arm module 7L starts moving. When the right side pointer 2R reaches the predetermined projection position of the cross mark, the μPUIO can recognize the position of the arm module 7R by the number of drive pulses, so the position of the cross mark can be determined by the calculation method described above based on the table in FIG. Calculate the position of the arm module 7L from the position of the obtained cross mark,
μPUIO sends a drive pulse to the left screen pointer movement motor 5L to move it to the calculated position.

The above operation will be explained with reference to the flowchart shown in FIG.

Step 1 Manually turn on the operation command switches for the left and right side pointer movement motors 5R and 5L. μPUI0 sends a drive pulse to the left and right side pointer movement motors 5R and 5L to cause them to move up or down. The right side pointer moving motor 5R starts rotating, and the arm module 7R starts moving. The left side pointer moving motor 5L starts rotating with a little delay, and the arm module 7L starts moving following the arm module 7R.

Step 2 Arm modules 7R and 7L continue to move.

Step 3: The μPUIO checks whether the switch is turned off because the cross mark has reached a predetermined position, that is, whether the raising and lowering of the arm module 7R has been completed. If not finished, return to step 2. If finished, proceed to step 4.

Step 4 μPUIO stops the drive pulse sent to the right side pointer movement motor 5R, and the arm module 7R stops moving.

Step 5 μPUIO recognizes the position of the arm module 2R from the number of drive pulses sent to the right side pointer movement motor 5R, and with reference to the table in Figure 3, calculates the cross mark as explained in Figure 4. Find the location. In the figure, μP U 1. Assuming that the position of the arm module 7R recognized by O is 25.4, the coordinate Q of the horizontal axis of the point E on the curve is calculated by the following equation.

−． Q.25. 48 Step 6 Now that the position of the cross mark on the projection plane of the right side pointer 2R has been obtained, the position of the arm module 7L is determined from this position, that is, the position of the cross mark 25.48 cm from the ground, and the position of the arm module 7L and the cross mark is It is obtained by performing the inverse calculation of the above calculation from the position table.

Step 7 In order to move the arm module 7L by an amount corresponding to the difference between the current position and the position obtained in Step 6, μP
The UIO sends the drive pulse to the left side pointer movement motor 5L.
to move the arm module 7L, and if the calculated positions of the left and right cross marks match, the arm module 7L is moved.
Stop L.

As explained above, it is now possible to correct the mismatch between the left and right cross marks due to the amount of mechanical distortion, especially when setting the cross marks at arbitrary positions, where it was previously difficult to control the position to the same position. However, according to this embodiment, one arm module is operated to follow the other arm module, and the position calculation is performed using a table stored in the μPU, so that there is no misalignment of the left and right marks. It becomes possible to control the arm module.

It should be noted that the positioning control method described in this embodiment can be applied to a positioning apparatus having a similar configuration, rather than a positioning apparatus for 44-radiation treatment planning.

(Effects of the Invention) As described in Detailed Explanation 1-1 above, according to the present invention, even when the projection position of the cross mark is set arbitrarily, a cross mark is projected in which the left and right pointers accurately match the position. It has become possible to do so, and the practical effects are great.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment for carrying out the method of the present invention, Fig. 2 is a flowchart of a control method when setting the arm module at an arbitrary position according to the embodiment, and Fig. 3 shows the amount of arm module movement and A graph showing the relationship between the cross mark position error, Figure 4 is an explanatory diagram for calculating the amount of arm module movement to move the cross mark correctly, and Figure 5 is an X-ray C graph.
FIG. 6, which is a layout diagram of the pointer in the T room, is an explanatory diagram of occurrence of a cross mark movement amount error due to pointer movement. 1... Center pointer 2L... Left side pointer 2R... Right side pointer 3... Center pointer movement motor 4... Center pointer position sensor 5L... Left side pointer movement motor 5R... Right side Surface pointer movement motor 6L...Left side pointer position sensor 6R...Right side pointer position sensor

Claims (1)

[Claims] An arm module (7S
, 7L and 7R), and the arm module (7S
, 7L and 7R) and a central, left and right side pointer movement motor (3, 5L and 5R) for moving the arm module (7S, 7L and 7R) unit by unit movement of the arm module (7S, 7L and 7R). Center, left and right side pointers (1, 2L and 2
a step of actually measuring the position of R) and the position of the corresponding mark and storing the data in μPU (10); and an arm module (7R or 7L) on either side.
the arm module (7L or 7R) on the other side, and the step of moving the arm module (7L or 7R) by raising or lowering the arm module (7R) on the other side.
or 7L), and calculating the position of the mark on one side from the position of the arm module (7R or 7L) based on the data stored in the μPU (10). a step of calculating the feed amount from the current position of the other arm module (7L or 7R) from the position of the mark determined by the calculation based on the data stored in the μPU (10); From the feed amount of the other arm module (7L or 7R), the left or right side pointer movement motor (5L or 5
Positioning for radiation therapy planning, characterized by comprising the steps of: calculating the number of pulses to be sent to R); and sending a signal of the calculated number of pulses to the left or right side pointer movement motor (5L or 5R). How to control the device.