WO2011021410A1 - Radiation treatment system - Google Patents

Abstract

Disclosed is a radiation treatment system capable of performing proper treatment based on treatment planning, by dynamically changing the irradiation condition according to the movement of an organ and accurately evaluating the dose distribution. Specifically disclosed is a radiation treatment system provided with a four-dimensional treatment planning device (11) which holds a plurality of three-dimensional images captured for respective respiratory phases, and treatment planning data (RTP) generated for each of the plurality of three-dimensional images, a region-to-be-treated displacement measurement device (12) which measures the displacement of a region to be treated, a respiratory phase calculation device (13) which calculates the respiratory phases on the basis of data relating to the measured displacement and the plurality of three-dimensional images, an irradiation control unit (15, 16) which controls an irradiation device (17) on the basis of the calculated respiratory phases and the treatment planning data, and a dose distribution evaluation unit (20) which evaluates the dose distribution of radiation, wherein the dose distribution evaluation unit (20) superposes dose distributions calculated for the respective respiratory phases on the basis of the treatment planning data corresponding to the respective respiratory phases, and controls the amount of radiation according to the superposed dose distributions.

Description

Radiation therapy system

The present invention relates to a radiotherapy system for performing treatment by irradiating a diseased tissue in a body with radiation, and in particular, for performing high-accuracy radiotherapy for an organ that moves with breathing of a patient being treated. Regarding technology.

Radiation therapy is to damage tumor cells by irradiating a cancer lesion with a dose of radiation necessary. In radiation therapy, various types of radiation, such as charged particle beams, neutron beams, gamma rays, X-rays, and electron beams, can be used. On the other hand, it is necessary to suppress exposure to normal cells as much as possible. Therefore, in radiotherapy, in order to perform optimal treatment, irradiation is performed based on a treatment plan in which a dose, an irradiation range, an irradiation angle, and the like are determined. Furthermore, for organs that move mainly under the influence of respiration, such as the lung, liver, and pancreas, a method in which a respiration signal is monitored and radiation is applied in accordance with a specific respiration amplitude or respiration phase has been adopted. However, since the position of the treatment target part in the living body was estimated from the respiration signal of the body surface, the movement of the treatment target part could not be accurately grasped, and the radiation could not be irradiated accurately.

Therefore, a radiotherapy system has been proposed that directly observes the movement of a treatment target part in real time using X-ray fluoroscopy and ultrasonic waves, and controls radiation irradiation based on the directly observed movement vector of the treatment target part. . (For example, refer to Patent Documents 1 and 2).

JP 2005-185336 A (paragraphs 0084 to 0086, FIG. 12) Japanese Unexamined Patent Publication No. 2003-111010 (paragraphs 0029 to 0035, FIGS. 1 and 2)

However, in the radiotherapy system described above, the irradiation position and irradiation direction of the radiation are dynamically changed based on the movement vector of the treatment target part, but the influence on the treatment plan when the irradiation position and irradiation direction are changed, that is, The difference between the dose distribution in the treatment plan and the dose distribution in the actual irradiation is not considered. Therefore, the evaluation of the dose distribution to the treatment target site and its peripheral part becomes inaccurate, and it is difficult to perform appropriate treatment based on the treatment plan.

The present invention has been made to solve the above-described problems, and dynamically changes the irradiation position and irradiation direction according to the movement of the treatment target region and accurately evaluates the dose distribution. An object of the present invention is to obtain a radiotherapy system capable of performing appropriate treatment based on a treatment plan.

A radiotherapy system according to the present invention includes an irradiation device that irradiates a patient to be treated with radiation, a plurality of three-dimensional images captured in advance for each respiratory phase of the patient, and each of the plurality of three-dimensional images. A four-dimensional treatment planning apparatus that holds treatment plan data generated for the treatment target, a treatment target part displacement measuring device that measures a real time displacement of the treatment target part, and a real time of the measured treatment target part. A respiratory phase calculation device that calculates a respiratory phase based on displacement data and the plurality of three-dimensional images; an irradiation control unit that controls the irradiation device based on the calculated respiratory phase and treatment plan data; A dose distribution evaluation unit that evaluates a dose distribution of radiation irradiated to a treatment target site, the dose distribution evaluation unit based on treatment plan data corresponding to the respiratory phase With computing, overlay dose distributions calculated for each of the breathing phase, and controlling the irradiation amount of radiation in accordance with the superimposed dose distribution.

According to the present invention, the irradiation position and the irradiation direction are dynamically changed according to the respiratory phase, and the dose distribution is evaluated using the treatment plan corresponding to the respiratory phase. A radiation treatment system capable of performing treatment can be obtained.

It is a block diagram which shows the structure of the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the four-dimensional CT image used with the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the four-dimensional treatment plan used with the radiotherapy system concerning Embodiment 1 of this invention. It is a schematic diagram which shows the structure of the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the four-dimensional volume data used with the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the three-dimensional measuring apparatus in the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the correlation calculation in the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the irradiation timing in the radiotherapy system concerning Embodiment 1 of this invention. It is a figure for demonstrating the determination method of the irradiation timing in the radiotherapy system concerning Embodiment 1 of this invention. It is a block diagram which shows the structure of the radiotherapy system concerning Embodiment 2 of this invention. It is a schematic diagram which shows the structure of the radiotherapy system concerning Embodiment 2 of this invention. It is a block diagram which shows the structure of the radiotherapy system concerning Embodiment 3 of this invention. It is a block diagram which shows the structure of the radiotherapy system concerning Embodiment 4 of this invention. It is a figure for demonstrating the correlation calculation in the radiotherapy system concerning Embodiment 4 of this invention.

Embodiment 1 FIG.
1 to 9 are diagrams for explaining the radiation therapy system according to the first embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of the radiation therapy system, and FIG. 2 is a diagram for explaining a four-dimensional CT image. FIG. 3 is a diagram for explaining a four-dimensional treatment plan, FIG. 4 is a schematic diagram of a radiation treatment system, FIG. 5 is a diagram for explaining four-dimensional volume data, and FIG. 6 is for a three-dimensional measurement apparatus. FIG. 7 is a diagram for explaining the correlation calculation, FIG. 8 is a diagram for explaining the irradiation timing, and FIG. 9 is a diagram for explaining a method for determining the irradiation timing.

As shown in FIG. 1, the radiotherapy system according to Embodiment 1 of the present invention includes a plurality of three-dimensional CT image data groups having different phases in one respiratory cycle of a patient to be treated (a combination of four-dimensional CT images and 4D treatment having a 4D treatment database for storing a plurality of 3D treatment plan data (collectively referred to as 4D treatment plan data) generated for each of a plurality of 3D CT image data groups. The planning apparatus 11, the treatment target part displacement measuring device 12 that measures displacement (organ movement) of the treatment target part in real time, the measured displacement data of the treatment target part in real time, and the plurality of three-dimensional images. In comparison, a respiratory phase calculation device 13 that calculates a respiratory phase, and irradiation control signals and phase signals such as irradiation timing, irradiation position, and angle according to the respiratory phase and the position of the treatment target part An irradiation control signal generation unit 15 to output, an irradiation control unit 16 that controls the irradiation device 17 based on the irradiation control signal, and a three-dimensional treatment selected from four-dimensional treatment plan data according to the respiratory phase (phase signal) A dose distribution evaluation unit 20 that evaluates the dose distribution based on the plan. The dose distribution evaluation unit 20 superimposes the dose distributions evaluated using the treatment plan data corresponding to the respiratory phase for each respiratory phase, The irradiation end signal for ending the beam irradiation is output to the irradiation control unit 16 when the dose distribution reaches the target. Details will be described below.

First, the 4D treatment plan data handled by the 4D treatment plan device 11 will be described. FIG. 2 is a conceptual diagram showing the configuration of a four-dimensional CT image that is taken in advance with respect to a treatment target site of a patient by the four-dimensional treatment planning apparatus 11. The four-dimensional CT image is a normal three-dimensional CT image (stereoscopic image) added with the concept of the time axis direction, and is defined as a group of three-dimensional CT images arranged in time series. In the first embodiment, a group of 3D CT images for each of N respiratory phases arranged in order during one respiratory cycle of a patient undergoing radiation therapy is referred to as a 4D CT image. That is, the four-dimensional CT image can be said to be a collection of stereoscopic image data for each respiratory phase of an organ that periodically moves under the influence of respiration in the trunk region.

Here, a general imaging method for 4D CT images will be described. A CT image for treatment planning is taken with the subject (patient) wearing a respiration sensor. There are two imaging methods: “CT imaging with gating” and “CT imaging without gating”. As the respiration sensor, an externally installed strain gauge, a body surface marker detection camera, or a laser displacement meter can be used. Both measure the vertical motion of the body surface accompanying breathing. In addition, a general respiration sensor such as a thermistor or a ventilation meter can be used.

“CT imaging with gating” refers to performing CT imaging with a trigger for each respiratory amplitude or respiratory phase during one respiratory cycle, and sequentially obtaining a plurality of CT images with different respiratory amplitudes or respiratory phases. Is the method. When shooting a wide area, it is necessary to move the bed in the cine mode, and it is necessary to trigger each breathing amplitude or breathing phase for each bed position, which is a time-consuming and time-consuming method. Also called Prospective CT imaging.

On the other hand, in “CT imaging without gating”, a trigger is not applied for each respiratory amplitude or respiratory phase, but respiratory amplitude information or respiratory phase information is added to each projection data in the X-ray tube rotation imaging of the CT apparatus. In addition, continuous imaging is performed between several respiratory cycles. When a wide area is to be imaged, similar imaging is performed for each bed position in the cine mode. Thereafter, each projection data at each couch position is sorted by respiration amplitude or respiration phase, and an image is reconstructed only from projection data of a predetermined respiration amplitude or respiration phase. In this way, CT images with a plurality of respiratory amplitudes or phases can be obtained all at once, so “CT imaging without gating” is an advantageous method in terms of efficiency. It is also called retrospective CT imaging.

In any method, the CT image for treatment planning using 4D CT is an image with no respiratory amplitude or phase and no blurring due to respiration. Therefore, it is possible to improve the accuracy of treatment planning. Become.

The four-dimensional treatment plan apparatus 11 generates a so-called treatment plan for each of the three-dimensional CT images having different phases in the four-dimensional CT image obtained as described above. In the treatment plan, the irradiation target is identified from the position and shape of the cancer lesion (the site to be treated), the direction of irradiation and the distribution of the irradiation dose are simulated, the validity of the treatment is evaluated, and the irradiation device 17 To determine the treatment parameters required for beam irradiation. Here, assuming that there are N three-dimensional CT images, N treatment plans (RTP ₁ to RTP _N ) are created as shown in FIG. The treatment plan for each phase is based on the three-dimensional shape of the treatment target part itself in that phase, the surrounding tissue, the depth from the body surface when irradiating radiation, and the like in various directions (see FIG. Then, there are two directions, but there may be more directions, or only one direction. Especially when using a charged particle beam, this treatment plan is called the Bragg peak, and the depth at which the beam energy is absorbed by the kinetic energy of the charged particle beam (the depth from the body surface of the irradiated tissue) is determined. Is important in controlling the irradiation of cancer lesions and the exposure of surrounding tissues. N generally corresponds to a number that divides one respiratory cycle, and is generally about N = 10, but is not limited to this number. The three-dimensional treatment plan data generated for each phase of the respiratory cycle (collectively referred to as four-dimensional treatment plan data) is stored in the four-dimensional treatment plan database 111.

As shown in FIG. 4, the treatment target region displacement measuring apparatus 12 is connected to the three-dimensional ultrasonic diagnostic apparatus main body 21, the ultrasonic probe 22 connected to the three-dimensional ultrasonic diagnostic apparatus main body 21, and the ultrasonic probe 22. And a support fixture 23 that can measure the movement of the internal organs (displacement of the treatment target site) in close contact with the trunk body surface. As a result, a moving organ can be measured in real time in the trunk region. As described above, by collecting the three-dimensional volume data in real time using the three-dimensional ultrasonic diagnostic apparatus, it is possible to collect the four-dimensional volume data of the internal organ. As shown in FIG. 5, four-dimensional volume data (three-dimensional volume data group) is configured by accumulating the three-dimensional volume data (VD ₁ to VD _M ) from time to time in order of time series. This basic principle is the same as that of four-dimensional CT, but in the case of ultrasonic waves, the data acquisition time is short, and volume data having a sampling interval shorter than that of CT can be acquired in real time. . Here, the ultrasonic wave is described as the treatment target region displacement measuring device 12, but the ultrasonic wave is not limited to the ultrasonic wave, and any means capable of measuring internal organ movement such as fluoroscopy may be used.

The respiratory phase calculation device 13 collates the three-dimensional shape and position information of the cancer lesion that changes with breathing measured by the treatment target part displacement measuring device 12 with the four-dimensional treatment plan data generated in advance, and calculates the respiratory phase. A three-dimensional position measuring unit 131 that converts the four-dimensional volume data measured by the treatment target region displacement measuring device 12 into three-dimensional coordinates in the treatment room, and a four-dimensional volume that has been captured and recorded in advance A correlation calculation unit 132 that collates the data with the information of the three-dimensional shape and position measured in real time, performs three-dimensional tracking of the treatment target region to be irradiated, and calculates a respiratory phase;

The three-dimensional position measurement unit 131 is a so-called three-dimensional measurement device, and includes measurement markers 41 to 43, cameras 44 and 45 that detect the measurement markers, and the like. This will be specifically described with reference to FIG. Measurement markers 41 to 43 are attached to the casing of the ultrasonic probe 22, and the measurement markers 41 to 43 are recognized from the cameras 44 and 45 installed on the ceiling or the like, and three-dimensional coordinate values are calculated. The cameras 44 and 45 are composed of two or more units, and realize three-dimensional measurement by so-called stereo vision. This three-dimensional coordinate value is a value in the treatment room coordinate system with the isocenter C that is the irradiation center of the radiation beam as the origin, and by recognizing three or more measurement markers, the position and posture of the ultrasonic probe 22 can be determined. It can be measured. This can be realized by obtaining a conversion formula between two coordinate systems of the coordinate system of the three-dimensional position measurement unit 131 and the treatment room coordinate system by a prior calibration operation.

Further, using an ultrasonic phantom or the like, two coordinate systems, that is, a coordinate system of the ultrasonic diagnostic apparatus 21 of the treatment target region displacement measuring apparatus 12 and a coordinate system extended by measurement markers 41 to 43 attached on the ultrasonic probe 22 are used. The conversion formula between them can also be obtained in advance. The coordinate system of the ultrasound diagnostic apparatus 21 and the coordinate system of the measurement marker, the coordinate system of the measurement marker, the coordinate system of the measurement marker, and the treatment room coordinate system are known. Can be associated with coordinates in the treatment room coordinate system. The above is a description of the case where the ultrasonic probe 22 is movable. However, the ultrasonic probe 22 may be fixed to an inoperable part in the treatment room, such as being embedded in a treatment table or supported by a fixed arm. Even in this case, by obtaining the relationship between the coordinate system of the ultrasonic diagnostic apparatus 21 and the treatment room coordinate system in advance, it is possible to associate the coordinates of the two.

Next, the correlation calculation unit 132 will be described with reference to FIG. The correlation calculation unit 132 performs three-dimensional tracking of the treatment target portion Ta, which is an irradiation target, using the four-dimensional volume data obtained from the ultrasonic diagnostic apparatus main body 21 and subjected to coordinate conversion by the three-dimensional position measurement unit 131. In any three-dimensional volume data measured by the frame VD _S, it sets the existing ROI (Region of Interest) region of the target site to be treated Ta as an area RI. The setting of the region RI can be performed manually or automatically. In the case of automatic, at least one of the contour information of the treatment target site Ta stored in the four-dimensional treatment plan database 111 may be used, and the region most suitable for the contour may be set as the region RI. In this automatic setting, the same correlation calculation as described below can be used. A search region RS is set for the three-dimensional volume data VD _j acquired after the frame in which the region RI is set, a correlation is calculated with the region RI, and a position where the correlation value is maximized is obtained.

Specifically, the correlation between the two is calculated while scanning the region RI within the search region RS. The scanning at that time may be only translation with three degrees of freedom or a combination of translation with three degrees of freedom and rotational movement with three degrees of freedom. As the correlation value, a normalized cross-correlation method that is robust to uniform luminance fluctuations is used. However, the similarity measure is not limited to the normalized cross-correlation method, and a probabilistic similarity measure such as a mutual information amount can also be used. Moreover, it is not necessarily limited to these.

Then, the phase that minimizes the distance between the measured treatment target site Ta and the treatment target site Ta in the four-dimensional treatment plan data is calculated as the current respiratory phase.

Further, the correlation calculation unit 132 may be equipped with a GPU (Graphic Processing Unit) and may perform correlation calculation with a plurality of volume data instantaneously by utilizing high-speed parallel calculation. In this way, by introducing matching using four-dimensional volume data, the respiratory phase can be calculated by tracking with a truly three-dimensional accuracy.

The irradiation control signal generation unit 15 generates irradiation control signals and phase signals such as irradiation timing, irradiation position, and angle according to the calculated respiratory phase (and corresponding treatment plan data) and the displacement of the treatment target site Ta. And output to the irradiation control unit 16 and the dose distribution evaluation unit 20.

Of the functions of the irradiation control signal generation unit 15, the irradiation timing control will be described first. Specifically, as shown in FIG. 8, the phase range in which beam irradiation is possible may be determined in advance among the three-dimensional treatment plan data for each phase of the four-dimensional treatment plan data RTP _4D . In FIG. 8, three phases (RTP _i−1 , RTP _i , RTP _{i + 1} ) of the (i−1) -th division, the i-th division, and the (i + 1) -th division among the N breathing periods are divided into beams. It is set as a range where irradiation is possible.

The phase selected as the irradiation possible range is such that the deformation or movement of the treatment target site Ta is small or its variation is small, and the treatment target site Ta can be irradiated with high accuracy, that is, high accuracy is maintained. A phase that allows continuous irradiation with ease is preferable. Further, if a range that does not greatly change the operation of the irradiation device 17 is selected, the change of the irradiation position and the irradiation angle can be reduced. In particular, in the case of the charged particle beam having the Bragg peak described above, if the change in irradiation depth is small, the amount of change in the kinetic energy of the charged particle beam can be reduced. It is preferable to do.

Further, as shown in FIG. 9, the position of the treatment target site Ta in the three-dimensional treatment plan data in the phase (division) and the tracking result of the treatment target site Ta analyzed by the correlation calculation unit 132 and the three-dimensional position measurement unit 131 When the distance L is smaller than the preset threshold value Th, it is determined that the treatment target site Ta belongs to the irradiation enabled range, and a beam irradiation enabled signal is generated. On the other hand, when the distance L between the position of the treatment target site Ta in the division and the tracking result of the treatment target site Ta in the correlation calculation unit 132 and the three-dimensional position measurement unit 131 is equal to or greater than a preset threshold Th, It is determined that the treatment target site Ta does not belong to the irradiation enabled range, and a beam irradiation impossible signal is generated. This is because the three-dimensional data of the treatment target part Ta measured by the treatment target part displacement measuring device 12 by the three-dimensional measurement means 131 is the same coordinate system (treatment room coordinate system) as the four-dimensional treatment plan data RTP _4D. This can be achieved by expressing the above.

In this example, a case where one breathing cycle is divided into N by phase is shown, but even when one breathing cycle is divided into N by amplitude, a signal indicating whether or not beam irradiation is possible can be generated by the same method. When divided by amplitude, there are two beam irradiation ranges within the same division, so from the direction of change in the amplitude of breathing, determine whether it is the expiratory phase or the inspiratory phase, It is necessary to determine which of the two beam irradiation ranges is to be used. Further, the regions do not need to be continuous, and a plurality of discrete regions can be selected.

Further, the irradiation control signal generation unit 15 sends an irradiation control instruction to the irradiation control unit 16 to change the irradiation position and irradiation direction of the beam based on the respiratory phase and the three-dimensional treatment plan data corresponding to the respiratory phase. . Therefore, the operation of the irradiation device 17 is controlled by the irradiation control signal generator 15 and the irradiation controller 16.

The irradiation device 17 controls the irradiation control unit 16 to emit a beam from the specified irradiation position and direction toward the treatment target site Ta when a beam irradiation enable signal comes from the irradiation control signal generation unit 15. Try to irradiate. Thereby, the irradiation device 17 can continuously irradiate the treatment target site Ta while changing the irradiation position and irradiation direction of the beam, and efficient treatment is possible.

Then, the treatment plan for each phase prepared by the four-dimensional treatment planning apparatus 11, information on the phase, and information on the change of the irradiation position and the irradiation direction are also output to the dose distribution evaluation unit 20. Each time the beam irradiation position or irradiation direction is changed according to the information such as the input phase, the dose distribution evaluation unit 20 also changes the treatment plan from which the dose distribution is calculated, and the treatment target part Ta and the treatment target part Ta The doses of the organs of attention in the vicinity of are superimposed. At this time, the treatment target portion Ta is moved and deformed, and the attention organ in the vicinity of the treatment target portion Ta is also moved and deformed. Therefore, the superposition is performed as a non-rigid matching process. In this way, the dose distribution for each respiratory phase is finally superimposed so that the dose distribution can be accurately evaluated. In the treatment plan dose distribution after being superposed, when the irradiation dose as the treatment plan target is reached, a signal is sent to the irradiation control unit 16 and the beam irradiation is terminated. The dose distribution evaluation unit 20 may be provided with a data recording unit (not shown) so as to record how much dose has been irradiated for each phase.

As described above, the radiation therapy system according to the first exemplary embodiment of the present invention includes the irradiation device 17 that irradiates radiation to the treatment target site Ta of the patient and the patient's ( 4D treatment holding a plurality of 3D images (4D CT images) captured in advance for each respiratory phase (in one respiratory cycle) and treatment plan data RTP generated for each of the plurality of 3D images The planning apparatus 11, the treatment target part displacement measuring device 12 that measures the real time displacement of the treatment target part Ta, the measured real time displacement data of the treatment target part Ta, and a plurality of three-dimensional images captured in advance Based on the above, the respiratory phase calculation device 13 that calculates the respiratory phase, the irradiation control units 15 and 16 that control the irradiation device 17 based on the calculated respiratory phase and the treatment plan data, and the treatment pair A dose distribution evaluation unit 20 that evaluates the dose distribution of the radiation irradiated to the part Ta, and the dose distribution evaluation unit 20 calculates a dose distribution for each respiratory phase based on treatment plan data corresponding to the respiratory phase. Since the calculation is performed and the dose distribution calculated for each respiratory phase is superimposed, and the radiation dose is controlled according to the superimposed dose distribution, the response is based on the movement of the treatment target portion Ta that is the irradiation target. In addition to dynamically changing the irradiation position and direction, it is possible to accurately evaluate the dose distribution and perform appropriate treatment based on the treatment plan

In particular, the treatment target part displacement measuring device 12 takes a three-dimensional image of the treatment target part Ta in real time in order to measure the displacement (organ movement) of the treatment target part Ta, and the respiratory phase calculation device 13 takes the picture. Since the configuration is such that the respiratory phase is calculated by comparing the real-time three-dimensional image VD of the treatment target site Ta with a plurality of three-dimensional images captured in advance, the four-dimensional treatment planning apparatus 11 is planned. Matching of the treatment target portion Ta at the time of treatment is performed using the three-dimensional volume data using the moving path of the treatment target portion Ta and the real-time ultrasonic image. That is, the respiratory phase is calculated based on the comparison between the assumed position and the actual position in the treatment plan. Furthermore, the amount of deviation L from the assumed position is calculated, and the irradiation position and direction are controlled according to the calculated respiratory phase and position deviation amount L. Even if the position of the target portion Ta moves, the phase and the position of the treatment target portion Ta can be accurately captured. As a result, it is possible to accurately change the irradiation position and irradiation direction according to the respiratory phase and the actual position of the treatment target site Ta, and to perform accurate treatment according to the treatment plan. In addition, not only the expiratory phase (exhaled state) but also the inspiratory phase (exhaled state), including the inspiratory phase (irrigated state), can be irradiated in all the defined respiratory phases, such as notable effects Can be played.

In addition, a respiratory phase for irradiating radiation is determined in advance, and radiation is irradiated from the irradiation device 17 only when the respiratory phase calculated from the real-time displacement data of the treatment target site Ta matches the determined phase. Thus, for example, if a phase with a small deformation or movement of the treatment target portion Ta or a variation thereof is selected, the treatment target portion Ta can be irradiated with radiation with high accuracy. That is, continuous irradiation can be easily performed while maintaining high accuracy.

In the first embodiment, an example in which treatment plan data is created for each of three-dimensional CT images taken in advance has been described. However, the number of three-dimensional CT images is larger than the number of treatment plans. It may be left. In that case, 3D CT images are taken so as to complement the phase of each treatment plan (for example, when the number of treatment plans is N, the number of 3D CT images is 3N), and real-time data is complemented. If the CT image corresponding to the portion has the highest correlation, a treatment plan having a phase close to that of the three-dimensional CT image may be selected.

In addition, even when breath-holding irradiation for stopping breathing is assumed, the above-described method of comparing the image data at the time of treatment planning and the three-dimensional data of the treatment target portion Ta in real time can be applied. In this case, when the treatment plan is generated, the position of the treatment target portion Ta at the time of breath holding is measured as a three-dimensional image for each phase, and the treatment plan corresponding to the position is generated. Then, the position of the treatment target portion Ta of the patient in the breath holding state is measured in real time, and the measured position is compared with the three-dimensional image group to determine which breath holding state (corresponding to the phase). The dose distribution may be evaluated by changing the beam irradiation position and irradiation direction and selecting the treatment plan accordingly.

Embodiment 2. FIG.
The radiotherapy system according to the second exemplary embodiment of the present invention finds a dose distribution at the time of treatment by the ultrasonic probe 22 of the treatment target part displacement measuring device 12 that measures the position of the treatment target part Ta in real time (real time). In order to prevent this, a configuration for limiting the operation range of the ultrasonic probe 22 is provided. 10 and 11 are for explaining the radiation therapy system according to the second embodiment. FIG. 10 is a block diagram for explaining the radiation therapy system. FIG. 11 is a schematic diagram of the radiation therapy system. . As shown in FIG. 10, the radiotherapy system according to the second exemplary embodiment is obtained by adding an alarm generating unit 19 to the radiotherapy system according to the first exemplary embodiment. The position and posture of the ultrasonic probe 22 of the measuring device 12 can be monitored. Further, a signal for generating an alarm generation timing is transmitted from the irradiation control signal generation unit 15 b to the alarm generation unit 19. This alarm generation unit 19 functions as a part of the irradiation control unit.

In the four-dimensional treatment plan apparatus 11b, the beam line LB (corresponding to a line connecting the isocenter C from the center of the exit of the irradiation apparatus) for each treatment plan in the four-dimensional treatment plan database 111b. The relationship between the position of the ultrasonic probe 22 with respect to the dose and the error in dose distribution due to the presence or absence of the ultrasonic probe 22 in that positional relationship, that is, the influence on the dose distribution due to the presence of the ultrasonic probe 22 is stored as dose effect data. ing. Other parts are the same as those in the first embodiment, and thus detailed description thereof is omitted. FIG. 11 is a schematic diagram for explaining dose effect data. In the figure, if the ultrasonic probe 22 enters the dot-dash line indicated as 10% error, the dose may be disturbed by 10%, and the ultrasonic probe 22 enters the dot-dash line indicated as 5% error. This indicates that there is a possibility that the dose may be disturbed by 5%, and that the dose may be disturbed by 3% when the ultrasonic probe 22 enters the two-dot chain line indicated by an error of 3%. That is, the four-dimensional treatment plan database 111b stores data in which the three-dimensional position of the ultrasound probe 22 and the amount of dose variation are mapped for each treatment plan. In FIG. 11, since the ultrasonic probe 22 has entered the region with an error of 5%, a dose error of 5% at maximum may occur. Note that the setting of numerical values such as 10%, 5%, and 3% in FIG. 11 is an example, and an error can be set with an arbitrary value and an arbitrary fine pitch.

Next, the operation will be described.
In the three-dimensional position measurement unit 131, there is a possibility that the dose distribution may be disturbed with an error value equal to or greater than a preset threshold value (N%) as well as the case where the ultrasonic probe 22 is positioned on the beam line 47. When the ultrasonic probe 22 enters the region that has occurred, that is, the dose may exceed the set threshold, the alarm device 19 generates an alarm signal to notify the user and An interlock signal is sent to the control signal generation unit 15 so as to generate a signal indicating that the irradiation timing is not possible.

As described above, according to the radiotherapy system according to the second exemplary embodiment, the four-dimensional treatment planning apparatus 11b performs the ultrasonic probe 22 of the treatment target region displacement measuring apparatus with respect to the radiation beam center (beam line LB) for each treatment plan. Is stored, and the irradiation control unit stores the ultrasonic probe measured by the three-dimensional position measurement unit 131b of the respiratory phase calculation device 13b. Based on the position 22 and the stored dose effect data, the ultrasonic probe 22 is configured to include an alarm device 19 that issues an alarm when it is determined that the effect on the dose by the ultrasonic probe 22 is greater than a predetermined value. Disturbance of dose distribution due to.

In the second embodiment, the configuration in which the dose is not disturbed by the presence of the ultrasonic probe 22 has been described, but the ultrasonic probe 22 itself is not broken by radiation exposure. You may make it carry out radiation protection of 22 with metal cases, such as tungsten. In that case, since the ultrasonic probe 22 does not break down due to radiation exposure, an effect that the tracking of the treatment target portion Ta during treatment is stabilized can be obtained.

As the marker to be attached to the ultrasonic probe 22, an active marker that emits infrared light by itself or a passive marker that reflects infrared light can be used, and there is no problem in terms of radiation resistance. There is no need.

Embodiment 3 FIG.
In the radiotherapy system according to the third exemplary embodiment of the present invention, in order to accurately measure the position of the treatment target site Ta, the irradiation timing and the ultrasonic wave are used so that the radiation at the time of treatment does not become noise with respect to the ultrasonic probe 22. A configuration for controlling the operation timing of the probe 22 is provided. FIG. 12 is a block diagram for explaining the radiation therapy system according to the third embodiment. As shown in FIG. 12, the radiotherapy system according to the third exemplary embodiment transmits a signal for generating measurement timing from the irradiation control unit 16c toward the treatment target region displacement measuring device 12c. Since other configurations are the same as those of the radiation irradiation system according to the first exemplary embodiment, description thereof is omitted.

Next, the operation will be described.
In the figure, the irradiation control unit 16c receives a beam irradiation control signal from the irradiation control signal generation unit 15, and the period during which the beam is irradiated from the irradiation device 17 is super-real time in the treatment target region displacement measuring device 12c. Suspend sonic image acquisition. On the other hand, during the period in which the irradiation control unit 16c receives a beam non-irradiation control signal from the irradiation control signal generation unit 15 and the irradiation device 17 does not irradiate the beam, real-time ultrasonic waves in the treatment target region displacement measuring device 12c A measurement timing signal is output to the treatment target part displacement measuring apparatus so as to perform image acquisition. Thereby, the internal organ measuring means 12c does not acquire a real-time ultrasonic image while irradiating radiation from the irradiation device 17, and acquires a real-time ultrasonic image while not irradiating radiation from the irradiation device 17. It becomes like this.

As described above, according to the radiotherapy system according to the third exemplary embodiment, the displacement measurement of the treatment target site Ta by the ultrasonic probe 22 is interrupted during the period of irradiation with radiation from the irradiation device 17, and radiation is emitted from the irradiation device 17. Since the movement measurement of the treatment target part Ta is executed only during the period of no irradiation, background noise due to radiation irradiation can be reduced, and a clear ultrasonic image of the treatment target part Ta can be acquired. As a result, the tracking accuracy of the treatment target site Ta is improved, and radiotherapy can be performed according to the treatment plan.

Embodiment 4 FIG.
The radiotherapy system according to the fourth exemplary embodiment of the present invention does not use the three-dimensional position measurement unit 131 used in the first exemplary embodiment, and the real-time three-dimensional image data and the three-dimensional image for each phase of the treatment target site Ta. Are directly compared with each other to calculate the phase. FIGS. 13 and 14 are diagrams for explaining the radiation therapy system according to the fourth embodiment of the present invention. FIG. 13 is a block diagram for explaining the radiation therapy system, and FIG. 14 is a method for calculating the phase. It is a figure for demonstrating.

As shown in FIG. 13, in the correlation calculation unit 132d, the 3D CT image group captured in advance for the treatment plan and the position data of the treatment target site Ta measured in real time are coordinated by the 3D position measurement unit. Without performing the above, the phase is calculated by calculating the correlation. Specifically, the correlation calculation unit 132d includes an oblique section extraction unit (not shown) that extracts an arbitrary oblique section from the 4D ultrasound image data input from the 4D treatment plan database 111d. By directly comparing a scanning cross section of the 3D ultrasonic image data obtained from the treatment target part displacement measuring apparatus 12 with an arbitrary oblique cross section extracted from the 4D ultrasonic image data, the correlation between the two is calculated and the correlation is calculated. The phase of the three-dimensional ultrasound image data including the arbitrary oblique section having the highest value is determined as the phase at that time.

Alternatively, by directly comparing a scanning section of the three-dimensional ultrasound image data obtained from the treatment target region displacement measuring device 12 with an arbitrary oblique section of the four-dimensional CT image data obtained from the four-dimensional treatment plan database 111, The image correlation between the two modalities may be calculated, and the phase of the 3D CT image data including the arbitrary oblique section having the highest correlation value may be determined as the phase at that time. The tumor path can be determined from the specification of such an appropriate respiratory phase, and the irradiation control signal generation unit 15 can generate the irradiation timing signal.

Further, when there is no metal marker or the like in the organ and it is difficult to detect the phase only by correlation calculation, the following method can be used. At this time, for example, two orthogonal cross-sectional images (PS1 and PS2) obtained for each scanning plane as shown in FIG. 14 can be used as the real-time ultrasonic image. Then, the orthogonal second-sectional image to detect arterial, venous, or three section C _BT vascular BT as a main, such as the portal vein. From the three positional relationships, it is calculated which cross-section of the three-dimensional CT image data group stored in the four-dimensional treatment plan database 111d shows the current real-time ultrasonic image.

A specific method will be described with reference to FIG. The ultrasonic volume data VD _m is obtained from the treatment target region displacement measuring device 12. The respiratory phase calculation device 13d includes a scanning section extraction unit (not shown) that extracts two orthogonal scanning sections from the real-time three-dimensional image of the imaged treatment site. Then, the two scanning plane perpendicular generated from the ultrasound volume data VD _m as shown in FIG. 14 (a1) and the scanning plane PS1 and the scanning plane PS2. The fixing location of the ultrasonic probe 22 is determined so that three or more blood vessels pass on either the scanning surface PS1 or the scanning surface PS2. Figure 14 (a2), and vascular BT1, BT2, BT3 (collectively referred to as blood vessel BT in.) Of the cross-section _{C BT1, C BT2, C BT3} is reflected in the scanning plane PS1 as shown in FIG. 14 (a3). The extraction of these blood vessels BT can be performed by previously registering information on the blood vessels as a template in the four-dimensional treatment database 111d and using the correlation calculation unit 132d. In addition, as the blood vessel BT to be compared, if a main thick system having a small number of branches from the center, such as arteries, veins, and portal veins, is used, blood vessels are identified, that is, identified. Becomes easy.

Then, over time, the ultrasound volume data VD _n as shown in FIG. 14 (b1) and those obtained. At this time, the organ Org including the treatment target site Ta moves, and as shown in FIGS. 14 (b2) and 14 (b3), the cross sections C _BT1 , C _BT2 , BT3, BT3, blood vessels BT1, BT2, BT3 The positional relationship of _CBT3 also changes. The vascular BT1, BT2, from the positional change in the relationship between BT3 sectional _{C BT1,} C _{BT2, C BT3} respective center points (three points), to estimate the movement change itself organ Org containing the target site to be treated Ta. Although the description has been made using the ultrasound volume data here, the same estimation can be performed using the CT volume data at the time of treatment planning instead of the ultrasound volume data.

As described above, according to the fourth embodiment, the respiratory phase calculation apparatus 13d includes the oblique section extraction unit that extracts an arbitrary oblique section from a plurality of three-dimensional images, and the treatment target region displacement measuring apparatus 12 is provided. By directly comparing the scan section with the ultrasonic image data (three-dimensional) obtained from the above and the extracted oblique section, the correlation between the two is calculated and the phase is calculated. The phase can be calculated.

In particular, in the 4D treatment plan database 111d of the 4D treatment plan apparatus 11d, position data of a plurality of blood vessels BT1, BT2, BT3 around the treatment target site Ta (including the organ Org) is recorded for each treatment plan, and breathing is performed. The phase calculation device 13d includes a scanning section extraction unit that extracts two orthogonal scanning sections PS1 and PS2 from the real-time three-dimensional image of the imaged treatment site, and the real-time three-dimensional area around the imaged treatment target site Ta. since to calculate the predetermined scanning plane PS1, reflected in PS2 multiple vascular C _{BT1, C BT2,} the positional relationship between the blood vessel position data and compared with respiratory phase of C _BT3 image, if the marker is not present However, it is possible to track the treatment target site Ta and calculate the phase.

Note that the number 3, which is the number of detected blood vessels in the fourth embodiment, is not limited, and the phase can be calculated at two points if it is a characteristic blood vessel. On the other hand, the greater the number of detections, the better the accuracy of estimation of the movement change of the organ Org. Therefore, the number of detections may be appropriately determined according to the target organ Org and the configuration and state of the surrounding blood vessels. Since the positional relationship between the tumor path and the organ movement can be examined in advance at the time of treatment planning, the tumor path can be determined from the extraction of the organ movement, and the irradiation control signal generation unit 15d performs irradiation. A timing signal can be generated.

11 4D treatment plan device (111 4D treatment plan database),
12 treatment object part displacement measuring device, 13 respiratory phase calculating device (131 three-dimensional position measuring unit, 132 correlation calculating unit), 15 irradiation control signal generating unit, 16 irradiation control unit, 17 irradiation device, 19 alarm generating unit, 20 dose distribution evaluation unit, 21 3D ultrasound apparatus body, 22 ultrasonic probe, 23 support fixture 41 to 43 measurement markers, 44-45 camera, BT vascular, _{C BT} vessel cross-section (the image), C isocenter, LB Beam line, Org organ including treatment target site, PS1, PS2 scanning plane, RTP 3D treatment plan data, RTP _{4D 4D} treatment plan data, Ta treatment target site (irradiation target), VD 3D volume data.

Claims (7)

An irradiation device for irradiating the patient's treatment site;
A four-dimensional treatment that holds a plurality of three-dimensional images captured in advance for each respiratory phase of the patient with respect to the treatment target region and treatment plan data generated for each of the plurality of three-dimensional images. Planning equipment;
A treatment target part displacement measuring device for measuring a displacement in real time of the treatment target part;
A respiratory phase calculation device that calculates a respiratory phase based on the measured real-time displacement data of the treatment target site and the plurality of three-dimensional images captured in advance;
Based on the calculated respiratory phase and the treatment plan data, an irradiation control unit that controls the irradiation device;
A dose distribution evaluation unit that evaluates the dose distribution of radiation irradiated to the treatment target site, and
The dose distribution evaluation unit calculates a dose distribution based on the treatment plan data corresponding to the respiratory phase for each respiratory phase, and superimposes the dose distribution calculated for each respiratory phase to obtain a superimposed dose distribution. A radiation therapy system that controls the radiation dose in response. The treatment target part displacement measuring device captures a three-dimensional image of the treatment target part in real time,
In the respiratory phase calculation device, the real-time three-dimensional image of the imaged treatment target part is compared with the plurality of three-dimensional images captured in advance, and the respiratory phase is calculated.
The radiotherapy system according to claim 1. 3. The radiation control unit according to claim 1, wherein the irradiation control unit causes the irradiation apparatus to irradiate radiation only when the calculated respiratory phase matches a predetermined respiratory phase. 4. The radiation therapy system according to item. The four-dimensional treatment planning apparatus stores dose variation data relating the position of the probe of the treatment target region displacement measuring device with respect to the center of the radiation beam and the variation of the radiation dose to the treatment target region,
The irradiation control unit includes an alarm device that issues an alarm when it is determined that the influence on the dose distribution of the treatment target region is larger than a predetermined value based on the measured probe position and the dose effect data. The radiotherapy system according to any one of claims 1 to 3. Displacement measurement of the treatment target part is interrupted during a period during which radiation is emitted from the irradiation apparatus, and displacement measurement of the treatment target part is performed only during a period during which radiation is not emitted from the irradiation apparatus. The radiation therapy system of any one of Claims 1 thru | or 4. The respiratory phase calculation device includes an oblique section extraction unit that extracts an arbitrary oblique section from the plurality of three-dimensional images,
Comparing a predetermined scanning cross-section of the captured real-time three-dimensional image of the treatment target site with the extracted oblique cross-section, to calculate the respiratory phase,
The radiotherapy system according to claim 2. In the four-dimensional treatment plan apparatus, position data of a plurality of blood vessels around the treatment target site is recorded for each treatment plan,
The respiratory phase calculation device includes a scanning section extraction unit that extracts two orthogonal scanning sections from a real-time three-dimensional image of the imaged treatment site,
Calculating the respiratory phase from the positional relationship of the plurality of blood vessels shown in the extracted scanning section and the position data of the blood vessels,
The radiotherapy system according to claim 2.

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