JP2002291792A - Control method and device for eyeball radiation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wrong radiation to the outside of the irradiation range by positively controlling the nictitation occurring in external irradiation radiotherapy treatment of the eye and irradiating it corresponding to the control timing of the nictitation. SOLUTION: The irradiation of the radiation to the eyeball is made to stop at a lapse of a prescribed time after giving a sign for closing the eye.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling eye radiation, and more particularly to a blink that occurs during treatment, which is suitable for use in treating the eye with external irradiation radiation. The present invention relates to a control method and apparatus for an eyeball irradiation line capable of preventing illegal irradiation outside the irradiation range by positively controlling the blinking and irradiating radiation in accordance with the blink control timing.

[0002]

2. Description of the Related Art In recent years, a method for treating the eye with external radiation has been put to practical use. When irradiating this radiation,
In order to reliably irradiate radiation to the patient's eyeball, the patient's head is fixed with a fixture, and the patient is stared at a gaze device such as a gaze light source, thereby indirectly fixing the movement of the eyeball. . The timing of irradiation is determined by a doctor who monitors the movement of the eyes and eyelids. However, in the current treatment method, when eyeball and blinking movements occur, the doctor may delay the irradiation stop judgment and irradiate normal tissues outside the irradiation range. In addition, the patient is forced to stare and open his / her eyes until the treatment is completed, which is a burden.

[0003] With respect to the current state of such treatment, Japanese Patent Laid-Open No. 2000-3507 discloses an external irradiation radiation treatment technique for the eyeball.
42 and JP-A-10-15087 have been proposed.

The former Japanese Patent Laid-Open No. 2000-3 proposed by the applicant
In 50742, the input image obtained by the ITV camera 32 is processed by the image processing device 36 as shown in FIG. A device that detects the position of the eyeball and the blink from the presence or absence of the eyeball and controls the irradiation state of the eyeball irradiation line irradiated from the beam generation device 22 via the beamline 24 is described. In the figure, 10 is a patient, 30
Is an eyeball position measuring device including the ITV camera 32 and the image processing device 36, and generates an interlock signal and the like to the beam generating device 22 from information on the eyeball position and the like measured by the eyeball position measuring device 30. This is a motion compensation control device.

The latter Japanese Patent Application Laid-Open No. 10-15087 discloses that
Observing the movement of the patient's eyelids and eyeballs while quantifying it by image processing, the patient's line of sight is small, and the charged particle beam is irradiated only while the eyelids are open, and the patient's eyelids are open There is described an irradiation control device that changes the energy of the charged particle beam in front of the patient when the device is closed.

[0006] These techniques are effective as a system capable of automatically judging the timing of radiation irradiation, as a means of reducing the burden on doctors and patients, and improving the dose concentration on the affected part.

[0007]

However, in the conventional techniques, since image processing is applied to motion detection, as shown in FIG. 2, for example, the irradiation gate is closed after detecting the movement of closing the eyelid. Before the control, a delay time Td corresponding to the image processing time Ti occurs in addition to the image capture time Ts corresponding to the sampling cycle of the camera input. As a result, in the related art, the irradiation position is shifted, and the normal tissue outside the irradiation range is incorrectly irradiated. In addition, there is a problem that a delay time Td is generated before the irradiation is restarted even at the end of blinking. Furthermore, the prior art has a problem that since an image is input at each sampling cycle Ts of the camera, image processing cannot be started simultaneously with the movement of the detection target.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and positively controls blinks generated during treatment, and irradiates the blinks in accordance with the blink control timing.
It is an object to prevent unauthorized irradiation outside the irradiation range.

[0009]

SUMMARY OF THE INVENTION According to the present invention, when irradiating an eyeball with an irradiation ray, the irradiation of the irradiation ray to the eyeball is stopped when a set time elapses after giving a signal for closing the eye. Thus, the above-mentioned problem has been solved.

[0010] Further, the signal is given by a light emitting source which is being watched from the irradiation object in order to suppress the movement of the eyeball, so that a separate means for giving the signal is unnecessary.

[0011] Further, the set time can be changed in accordance with the individual difference of the irradiation target, so that precise control according to the individual difference is performed.

Further, the re-irradiation after the stop of the irradiation is performed when it is detected by the image processing that the eyes are reopened, so that the illegal irradiation at the time of opening the eyelids is reliably prevented.

[0013] The present invention also provides a computer program for performing any one of the above methods.

[0014] The present invention also provides a computer-readable recording medium on which the computer program is recorded.

According to another aspect of the present invention, there is provided an eyeball irradiation line control device for irradiating an eyeball with an irradiation line, a means for giving a signal for closing the eyes, and a set time has elapsed since the signal was given. Sometimes, the above-mentioned problem is solved by providing a means for stopping irradiation of irradiation light to the eyeball.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In the present embodiment, as shown in FIG. 3, a proton beam accelerator 50 for accelerating protons to a predetermined energy and a proton beam accelerated by the proton beam accelerator 50 are irradiated with an irradiation device 54.
Beam transport device (also referred to as beam line) 5 that leads to
2, an irradiation device 54 for adjusting the dose distribution of the proton beam guided by the beam line 52 and irradiating it in accordance with the shape of the affected part (here, the eye 12) of the patient 10, and a light emitting source as a gaze light source 60, a light emission control device 62 for controlling the light emission source 60, a CCD camera 64 for detecting the movement of the eye 12 of the patient 10, and an image processing device for processing the output of the CCD camera 64 72 and a motion detecting device 7 for detecting a motion from an output of the image processing device 72
(PC) 70 including the light emission control device 6
2 and an irradiation control device 80 for controlling on / off of irradiation by the proton accelerator 50 in accordance with the output of the motion detecting device 74. In the figure, 8 is patient 1
It is a fixing tool for fixing the head of 0.

The proton beam accelerator 50 converts protons to, for example, 2
The proton beam is accelerated to 35 MeV, and the accelerated proton beam is converted into, for example, four energies (2) by an energy analyzer (not shown).
(35, 190, 150, 110 MeV). A proton beam having a specific energy generated by the proton accelerator 50 is transferred to a beam transport device 52.
To the irradiation device 54.

In the irradiation device 54, as shown in FIG.
A device for spreading the beam horizontally (e.g.
A) is used to form a uniform dose distribution in the horizontal direction, and the maximum depth of the proton beam is adjusted by the fine degrader 54B. Further, using the ridge filter 54C,
A dose distribution (enlarged black peak) in the depth direction corresponding to the thickness of the lesion 12A is formed. Further, a bolus 54E for adjusting the depth of arrival of the proton beam for each irradiation in accordance with the three-dimensional shape of the lesion 12A, and a block collimator 54D and a final collimator 54F for passing only the beam in the shape of the lesion 12A and cutting the rest, and irradiating light. Is led to the lesion 12A of the patient 10.

As the CCD camera 64, a double-speed CCD camera capable of imaging at 60 frames per second is used instead of a normal CCD camera for imaging at 30 frames per second in order to detect high-speed movement of the eyes and eyelids. be able to.

The image processing device 72 and the motion detecting device 7
4 includes, for example, an image processing board built in the personal computer 70 and a motion detection program.

Hereinafter, the operation of the present embodiment will be described with reference to FIG.

The light emission control device 62 turns off the light emission source 60 at a light emission cycle (for example, once every three seconds) set before the treatment by a light emission cycle control program shown in a loop A. Then, as shown in FIG.
After the lapse of m, in order to turn off the irradiation gate by the irradiation control device 80, for example, “1” is written into the light emission control result of the shared memory of the personal computer 70. Further, after the blink duration time Ts + delay time Td has elapsed, “0” is written to turn on the irradiation gate again.

More specifically, as shown in detail in FIG. 7, by actively controlling the movement of the blink, the control signal of the irradiation gate is written into the light emission control result of the shared memory.
That is, when the irradiation is started, the light emission time of the light emission source 60 is controlled. The patient 10 blinks according to the light emission interval of the light emission source 60 by the light emission control device 62. That is, at the time of lighting (step 102), blinking is not performed and the eyelid opening state is maintained. On the other hand, blinking is performed from lighting to turning off.

At the timing of turning off the light (step 104), the light emitting source 60 changes from the lighting state to the turning off (step 106) and turns on again (step 102). After confirming that the light is turned off, the patient 10 starts blinking after the blink reaction time Tm (step 108). At the same time as the start of blinking, the irradiation gate-off signal "1" is written to the emission control result of the shared memory (step 110).

The motion detecting device 74 performs the same image processing as the conventional one by using the motion detecting program shown in the loop B, and determines whether or not the eye and eyelid motions are within the irradiation allowable range. When an unacceptable movement is detected, the irradiation control device 80
In order to turn off the irradiation gate, "1" is written to the motion detection result of the shared memory, and "0" is written otherwise.

More specifically, as shown in detail in FIG. 8, when irradiation is started, every irradiation cycle (step 20) is started.
A camera input is performed in 2) (step 204). After the image input, the motion detection requires a delay time Ti for the image processing time.
Occurs (step 206). After the motion detection by the image processing (step 208), it is determined whether or not the eye and eyelid motions are within the allowable range (step 210). If the motion feature value is larger than the motion determination threshold, it is considered that a motion outside the allowable range has occurred, and the irradiation gate-off signal “1” is written to the motion detection result of the shared memory (step 21).
2).

The irradiation control device 80 determines irradiation gate off by a logical sum of five irradiation gate off signals according to an irradiation gate control program shown in a loop C. That is, as shown in FIG. 9, the irradiation gate operates as follows: (1) when an irradiation stop signal is generated (step 300);
2 (step 304), and (3) non-permissible motion determination by the motion detection device 74 (step 30).
6), (4) Measure the actual irradiation dose from the irradiation device 54,
When the scheduled irradiation dose is satisfied (step 302), (5)
When the irradiation gate-off signal generated in any of the emergency button stops when an emergency occurs during the treatment (step 308) is input to the irradiation control device 80, it is turned off (step 310).

FIG. 6 shows an operation time chart of the irradiation gate by the blink control. In FIG. 6, the delay of the time Tm from the turning off of the light emitting source 60 to the start of blinking is a reaction time from when the patient 10 recognizes that the light emitting source 60 has turned off to when the eyelid is closed. The irradiation gate can be turned off at the same time as the start of the blink by preparing the blink response time Tm of each patient with respect to the blinking 60 of the light source before treatment as data.

On the other hand, even when the blink ends, it is possible to turn on the blink simultaneously with the end of the blink by preparing the blink duration time Ts as data before the treatment. However, if an eyeball movement outside the allowable range occurs at the end of the blink, as a result of the motion detection by the image processing, a delay of the Td time occurs, and there is a possibility that the illegal irradiation is performed outside the irradiation range. Therefore, it is desirable to determine whether the irradiation gate is on after the end of motion detection by image processing.

Here, the measurement of the blink response time Tm set before the treatment is performed, for example, as follows. FIG. 10 shows an image captured by the CCD camera 64, and FIG. 11 shows a displacement diagram of a feature amount with respect to blinking movement. For the measurement of these parameters, the CCD camera 64, the image processing device 72, and the motion detection device 74 are used.

First, as shown in FIG. 11, the eye 12 and the eyelid 14 are shown in the image taken by the CCD camera 64. In the figure, reference numeral 16 denotes an iris.

Therefore, an ROI (Region of Interest) is set in the boundary region between the eyeball 12 and the eyelid 14 for the captured image.

Then, the feature amount of the set area (for example, the average density of the area pixels) is calculated.

The movement of the eyelid 14 is determined by comparing the feature amount and the movement determination threshold value with respect to the continuously photographed images as shown in FIG. If the feature value is larger than the motion determination threshold, it is determined that an unacceptable shift has occurred with respect to the irradiation position, and the time Tm from when the light source is turned off to when blinking starts is measured.

In the present embodiment, since the gaze emission light source 60 is used as a signal for starting a blink, a means for giving a separate signal is unnecessary. It is also possible to give a signal to start blinking, for example, by voice or the like.

In the present embodiment, since the instantaneous response time Tm is variable, it can be adjusted according to individual differences. If there is little variation among patients,
It can be fixed.

In the above embodiment, the present invention is applied to the treatment by radiation. However, the application of the present invention is not limited to this. For example, a surgical treatment of the eye such as a cornea or myopia by a laser beam. The present invention can be similarly applied to a device or mechanical control by blinking of an eye controller or the like.

[0039]

According to the present invention, the blink is actively controlled, and irradiation is performed in accordance with the blink control timing.
It is possible to reliably prevent illegal irradiation outside the irradiation range.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a conventional irradiation gate control system proposed by the applicant in Japanese Patent Application Laid-Open No. 2000-350742.

FIG. 2 is a time chart for explaining a problem of the conventional example.

FIG. 3 is a block diagram showing the overall configuration of the embodiment of the present invention;

FIG. 4 is a perspective view showing a configuration of an irradiation device in the embodiment.

FIG. 5 is a diagram showing the entire operation of the embodiment.

FIG. 6 is a time chart showing the operation of the embodiment.

FIG. 7 is a flowchart showing a processing procedure of a light emission cycle control program in the light emission control device of the embodiment.

FIG. 8 is a flowchart showing a processing procedure of a motion detection program in the motion detection device.

FIG. 9 is a flowchart showing a processing procedure of an irradiation gate control program in the irradiation control apparatus.

FIG. 10 is a front view showing an example of an image of a CCD camera for explaining a method of measuring a blink reaction time Tm in the embodiment.

FIG. 11 is a time chart showing a change state of a feature amount with respect to a blinking movement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Patient 12 ... Eyeball 14 ... Eyelid 50 ... Proton beam accelerator 52 ... Beam transport device 54 ... Irradiation device 60 ... Light emission source 62 ... Light emission control device 64 ... CCD camera 70 ... Personal computer (PC) 72 ... Image processing device 74 ... Movement Detection device 80: Irradiation control device

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 4C082 AA01 AC05 AE01 AG05 AG08 AP08 AR02

Claims (7)

[Claims] 1. Irradiating the eye with irradiation light, wherein the irradiation of the irradiation light to the eye is stopped when a set time has elapsed since a signal for closing the eye is given when the irradiation of the eye is performed. Line control method. 2. The method according to claim 1, wherein the cue is given by a light source that is being watched from an irradiation target in order to suppress movement of the eyeball. 3. The method according to claim 1, wherein the set time can be changed in accordance with the individual difference of the irradiation target. 4. An eyeball irradiation line according to claim 1, wherein the re-irradiation after the stop of the irradiation is performed when it is detected by image processing that the eyes are opened again. Control method. 5. A computer program for performing the method according to claim 1. 6. A computer-readable recording medium on which the computer program according to claim 5 is recorded. 7. An eyeball irradiation ray control device for irradiating an eyeball with an irradiation ray, comprising: a means for giving a signal for closing the eye; and A control unit for stopping irradiation of the irradiation ray of the eyeball.