JP4264543B2 - Radiation therapy system - Google Patents

Description

  The present invention relates to a radiation therapy system, and more particularly to a system for performing radiation therapy in consideration of a three-dimensional movement of a target tissue in a living body.

  2. Description of the Related Art Radiotherapy systems that irradiate target tissues (such as malignant tumors) in the human body with radiation (such as proton beams, neutron beams, electron beams, and X-rays) are known. In such a system, it is strongly required to accurately irradiate only the target tissue so as not to damage the normal tissue as much as possible. In the treatment of each patient, for example, the posture is fixed for 10 to several tens of minutes, and thereby the spatial position of the target tissue is maintained. However, the spatial position of the target tissue may fluctuate due to respiration, body position change, and the like.

  Therefore, some conventional radiotherapy systems measure body surface position with laser light to cope with changes in body position due to breathing, etc., and only when the body surface position that fluctuates periodically is within a predetermined range. There is a system that performs control to allow radiation irradiation and to stop radiation irradiation in other cases. However, in such a method, the movement of the target tissue is only indirectly measured as the movement of the body surface. Therefore, it is desired to measure the movement of the target tissue more accurately in order to improve the therapeutic effect and further increase the safety.

  In the devices described in Patent Literatures 1, 2, 3, and 4, there is a technique for performing a correlation calculation between two ultrasonic images to obtain a probe movement amount and connecting the two ultrasonic images based on the movement amount. It is disclosed. However, there is no disclosure about detecting tissue motion. Patent Document 5 describes that a motion of a tissue or a blood flow is detected based on Doppler information obtained by transmitting and receiving ultrasonic waves. However, there is no disclosure regarding calculation of a three-dimensional tissue movement vector and application to a treatment system. Patent Document 6 discloses an apparatus that irradiates radiation or the like for ultrasonic wave transmission / reception and treatment in synchronization with a respiratory motion of a living body. Respiration is measured by a flow meter attached to the nostril. This Patent Document 6 also does not disclose obtaining the movement vector of the tissue itself. Non-Patent Document 1 discloses a technique for visualizing the movement of tissue details from ultrasonic echo data. However, there is no description about obtaining a target tissue movement vector, particularly a three-dimensional tissue movement vector. Non-Patent Document 2 discloses a system for obtaining a two-dimensional movement of a tissue from an ultrasonic image, but does not describe measuring a three-dimensional movement of the tissue.

  Conventionally, some ultrasonic diagnostic apparatuses form two orthogonal scanning planes (biplanes) and simultaneously display two orthogonal tomographic images. However, in such a device, measurement of tissue movement and dynamic control of the biplane are not performed.

US Pat. No. 6,416,477 US Pat. No. 5,782,766 US Pat. No. 6,159,152 US Patent Publication US2002 / 45825 JP-A-4-150841 Japanese Patent Publication No. 728869 Chikayoshi SUMI et.al, Phantom Experiment on Estimation of Sheer Modulus Distribution in Soft Tissue from Ultrasonic Measurement of Displacement Vector Field, IEICE Trans. Fundamentals, vol. E78-A, No. 12 Dec. 1995. Yoji Osanai et.al, High-Resolution Computation of 2-D Motion Sonogram, 2002 IEEE Ultrasonic Symposium, 1734-1738.

  As described above, in the conventional radiotherapy system, the three-dimensional movement of the target tissue is not observed, and in order to further improve the treatment effect and the safety, the three-dimensional movement of the target tissue. Real-time monitoring of movement is required.

  An object of the present invention is to enable appropriate radiation irradiation control by monitoring the three-dimensional movement of a target tissue in a living body in real time.

The system according to the present invention includes a radiotherapy apparatus that irradiates radiation to a target tissue in a living body, a three-dimensional tissue movement measurement apparatus that measures a three-dimensional tissue movement vector in real time for the target tissue, and irradiation of the radiation. A three-dimensional tissue movement measuring device having a two-dimensional array transducer , and in an orthogonal relationship by transmitting and receiving ultrasonic waves with the two-dimensional array transducer. Correlation between transmission / reception means for sequentially forming a first scanning surface and a second scanning surface and sequentially outputting frame data for each scanning surface, and two frame data having different time phases for each scanning surface Correlation calculation means for performing calculation, and a three-dimensional tissue movement vector for calculating a three-dimensional tissue movement vector based on the result of correlation calculation for each scanning plane. Includes a Le computation unit, wherein the irradiation control unit, the aiming position variable mode, the aiming position of the radiation on the basis of the three-dimensional tissue motion vector is variably controlled, the three-dimensional tissue movement measuring device, the sighting In the position variable mode, the positions of the first scanning plane and the second scanning plane are electronically adjusted so that the aiming position of the radiation is positioned on an intersection line of the first scanning plane and the second scanning plane. It includes a scanning control means for variably setting .

  According to the above configuration, the three-dimensional tissue movement measurement device using ultrasonic waves is measured in real time by the three-dimensional tissue movement measurement device, and using that or based on the three-dimensional position of the tissue calculated therefrom, Radiation irradiation control is performed. The radiation is a particle beam, electron beam, neutron beam, X-ray or the like.

In the above three-dimensional tissue movement measuring apparatus, the scanning planes are formed simultaneously or alternately by the wave transmitting / receiving means. The first scanning plane and the second scanning plane is Ru orthogonal relationship near. By repeatedly forming each scanning plane, a plurality of frame data having different time phases are acquired for each scanning plane. Correlation calculation is executed between two frame data having different time phases for each scanning plane. Then, the three-dimensional tissue movement vector is calculated from the result of each correlation calculation. In the correlation calculation, the entire frame data may be a target of the correlation calculation, or a reference area (a partial area including the target tissue) in the frame data may be a target of the correlation calculation. In the former case, the three-dimensional tissue movement vector represents the movement of the entire tissue included in each scanning plane, and in the latter case, the three-dimensional tissue movement vector represents the movement of the target tissue and its surrounding tissues. When the entire tissue including the target tissue moves due to respiration or body position change, it is sufficient to measure the movement of the entire tissue. When only the target tissue moves due to pulsation or the like, the tissue other than the target tissue refers to it. It is desirable to set the reference area so that it is not included in the area. The above correlation calculation may be performed between two frame data that are temporally adjacent to each other among a plurality of frame data acquired at a minute time interval, or after initial frame data as a comparison reference and It may be performed between the frame data of each time phase obtained. The calculated three-dimensional movement vector may be used for control as it is, or the absolute position (coordinates) in the three-dimensional space of the target tissue is calculated from the three-dimensional movement vector, and the position is used for control. Also good. In addition to the position, it is possible to calculate speed, acceleration, movement trajectory, and the like. To form each scan plane of the above to use the 3D probe with a 2D array transducer is not particularly desirable. The plurality of scanning planes are usually formed in a time-sharing manner, but they can be formed simultaneously if the received signals can be distinguished from each other.

  According to the above configuration, in obtaining the three-dimensional tissue movement vector, it is not necessary to repeatedly form the entire three-dimensional data capture space composed of a large number of scanning planes, and basically a small number of scanning planes are repeatedly formed. Therefore, the data acquisition rate can be increased, the calculation time can be reduced, and the motion information of the tissue can be obtained in real time. And if irradiation control of therapeutic radiation is performed using such measurement results, the therapeutic effect can be enhanced and at the same time the safety can be enhanced.

  In order to calculate the three-dimensional tissue movement vector, a plurality of scanning planes that intersect each other are formed. In this case, two scanning planes that are orthogonal to each other are formed from the viewpoint of improving the frame rate and reducing the amount of correlation calculation. On the other hand, from the viewpoint of improving the vector specifying accuracy, it is possible to form three or more scanning planes that intersect each other. In the latter case, the three-dimensional tissue movement vector is calculated from the result of correlation calculation for each scanning plane in consideration of the scanning plane crossing angle relationship. When three scanning planes are formed, the angle between the scanning planes is 60 degrees, and when four scanning planes are formed, the angle between the scanning planes is 45 degrees. Incidentally, the number of scanning planes may be selected by the user or automatically according to the size of the moving speed of the tissue and the size of the scanning plane. As a reasonable range of the number, for example, 2-4 can be mentioned. Of course, more scanning planes may be formed as necessary.

Desirably, the irradiation control device limits irradiation of the radiation when the position of the target tissue is out of an allowable range in the aiming position fixing mode .

  Preferably, the three-dimensional tissue movement measuring device includes a scanning control unit that controls the position of each scanning plane based on the result of the correlation calculation for each scanning plane. According to this configuration, the movement of the target tissue can be accurately measured by dynamically changing the position of each scanning plane according to the movement of the tissue.

  Preferably, the transmission / reception means includes an ultrasonic probe having a two-dimensional array transducer forming the plurality of one scanning planes, and an ultrasonic wave between the transmission / reception plane of the ultrasonic probe and the biological surface. And a liquid container that fills the sound wave propagation path with the coupling liquid. According to this configuration, even if the living body moves, the coupling liquid is always filled between the ultrasonic probe and the living body surface, so that the ultrasonic propagation is ensured even by such movement, Problems such as measurement interruptions can be prevented. In particular, there is an advantage that the burden on the living body can be reduced because it is not necessary to continuously press the wave transmitting / receiving surface of the ultrasonic probe against the living body and the living body need not be restrained more than necessary.

  Preferably, the three-dimensional tissue movement measuring device includes an image forming unit that forms an image based on frame data corresponding to each scanning plane. According to this configuration, the state of the target tissue can be observed in a pseudo three-dimensional manner.

  Preferably, the plurality of scanning planes include a first scanning plane and a second scanning plane that are orthogonal to each other, and the three-dimensional tissue movement measuring device or the irradiation control device is configured to perform the second scanning on the first scanning plane. Forming a first graphic image having a first line marker representing a position of a scanning plane and a first aiming position marker representing a radiation aiming position on the first scanning plane; and the first scanning on the second scanning plane. A graphic image forming means for forming a second graphic image having a second line marker representing the position of the surface and a second aiming position marker representing the aiming position of the radiation on the second scanning surface; and corresponding to the first scanning surface The first graphic image is synthesized with the first graphic image to form a first synthesized image, and the image corresponding to the second scanning plane and the second graphic image are synthesized with each other. Comprising an image combining means for forming a composite image, and display means for displaying the second composite image and the first synthesized image.

  According to the above configuration, the position and aiming position of the second scanning plane can be confirmed on the image corresponding to the first scanning plane (preferably the first tomographic image), and the image corresponding to the second scanning plane (preferably the first tomographic image). The position and aiming position of the first scanning plane can be confirmed on (2 tomographic images). Therefore, while observing the state of the target tissue at the time of treatment, it is possible to easily grasp the positional relationship between the first and second scanning planes and the positional relationship between the aiming position and the target tissue.

  In order to position the aiming position on each scanning plane, that is, it is desirable to appropriately set the position of each scanning plane so that the aiming position coincides with the intersection line of each scanning plane. In that case, when the aiming position is fixedly set, it is desirable that the position of each scanning plane is also fixedly set, and when the aiming position is dynamically changed following the movement of the target tissue. It is desirable to dynamically change the position of each scanning plane.

  Preferably, in the above configuration, in each correlation calculation, a reference area is fixedly set on one frame data, and the reference area data cut out from the reference area is the corresponding area data on the other frame data. To be compared. In that case, the position of the corresponding area on the other frame data is sequentially shifted for each correlation calculation. Then, the tissue movement component can be obtained from the position of the corresponding area that is most consistent. The reference area is set automatically or manually to include the target tissue. The central area of each scanning plane may be fixedly set as a reference area. In addition, the shift range of the corresponding area may be the entire other frame, but in order to shorten the calculation time, a predetermined partial range centered on the position of the reference area is also taken into consideration in consideration of the movement speed of the tissue. You may restrict to.

  Desirably, in each correlation calculation, the tissue movement component may be obtained from the position of the corresponding area data at the time when the correlation value becomes the smallest using a difference method, or a correlation value is obtained using a method such as a convolution calculation. The tissue movement component may be obtained from the position of the corresponding area data at the time when becomes the largest. Various methods can be used as the correlation calculation method.

  As described above, according to the present invention, three-dimensional movement of the target tissue in the living body can be monitored in real time to perform appropriate radiation irradiation control.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a preferred embodiment of the three-dimensional tissue movement measuring apparatus. The three-dimensional tissue movement measuring apparatus 10 is configured as an ultrasonic diagnostic apparatus incorporated in a radiation therapy system in the present embodiment. The configuration of the radiation therapy system will be described later with reference to FIGS. The radiotherapy system includes a control device 12 and an irradiation device (radiotherapy device) 14 in addition to the three-dimensional tissue movement measurement device 10. The irradiation device 14 is a device that irradiates a target tissue in a living body with radiation such as proton rays and X-rays. The control device 12 controls the operation of the entire system, and in particular controls radiation irradiation by the irradiation device 14.

  Hereinafter, the three-dimensional tissue movement measuring apparatus 10 will be described in detail. As described above, the three-dimensional tissue movement measuring apparatus 10 is configured as an ultrasonic diagnostic apparatus that performs ultrasonic diagnosis of a living body, and has a function of calculating a three-dimensional movement vector of a target tissue by transmitting and receiving ultrasonic waves. Have.

  In this embodiment, the probe 16 has a 2D array transducer. As will be described later with reference to FIG. 3, the 2D array transducer is configured by a plurality of vibration elements arranged two-dimensionally. An ultrasonic beam is formed by the 2D array transducer. In this embodiment, the ultrasonic beam can be scanned electronically freely in both the θ direction and the φ direction. Therefore, if a two-dimensional scan of an ultrasonic beam is performed using a 2D array transducer, a three-dimensional data capture space can be formed. In the present embodiment, a so-called biplane is formed by the 2D array transducer. The biplane is constituted by a first scanning plane and a second scanning plane that are orthogonal to each other. This will be described later with reference to FIG. Examples of the electronic scanning method include electronic sector scanning and electronic linear scanning.

  The transmission / reception unit 18 functions as a transmission beam former and a reception beam former. That is, at the time of transmission, a transmission signal is supplied from the transmission / reception unit 18 to a specific plurality of vibration elements in the 2D array transducer, thereby forming a transmission beam. At the time of reception, a plurality of reception signals output from a plurality of specific vibration elements in the 2D array transducer are subjected to phasing addition processing by the transmission / reception unit 18, thereby obtaining a reception beam, that is, a reception signal after phasing addition. .

  The control unit 20 controls the operation of each component provided in the three-dimensional tissue movement measuring apparatus 10, and in particular controls the transmission / reception unit 18, whereby the positions of the first scanning surface and the second scanning surface are controlled. Is controlling. The positions of the first scanning surface and the second scanning surface can be set by the user or automatically. An operation panel 37 is connected to the control unit 20, and the user can appropriately set the position of each scanning plane using the operation panel 37. Further, the control device 12 provides information on the radiation aiming position to the control unit 20, and the control unit 20 automatically sets the positions of the first scanning surface and the second scanning surface based on the information. May be.

  In the radiotherapy system according to the present embodiment, the aiming position fixing mode (first control mode) for fixing the aiming position of the radiation and the aiming position variable that dynamically changes the aiming position by following the movement of the target tissue. Mode (second control mode). In the former aiming position fixing mode, the initially set positions of the first scanning plane and the second scanning plane are fixedly maintained as they are, and in the latter aiming position variable setting mode, along with the dynamic change of the aiming position. That is, the positions of the first scanning surface and the second scanning surface are adaptively variably set in accordance with the movement of the target tissue. In this case, as will be described later, the aiming position of the radiation is included on each scanning plane (in other words, the center), in other words, the aiming position is always positioned on the intersection line of each scanning plane. The position of each scanning plane is set appropriately.

  The received signal after phasing addition output from the transmission / reception unit 18 is output to the first image forming unit 22 and the second image forming unit 24 in the present embodiment, in addition to the first tissue movement component calculation unit 26 and the second It is output to the tissue movement component calculation unit 28. Here, the first image forming unit 22 and the first tissue movement component calculation unit 26 are provided corresponding to the first scanning plane, and the second image formation unit 24 and the second tissue movement component calculation unit 28 are the first one. Two scanning planes are provided. However, the first image forming unit 22 and the second image forming unit 24 can be configured by a single image forming module, which is related to the first tissue movement component calculation unit 26 and the second tissue movement component calculation unit 28. The same can be said, and they can be constituted by a single tissue movement component calculation module. That is, when the first scanning plane and the second scanning plane are alternately formed in a time division manner, a single image forming module is operated in a time division manner corresponding to each scanning plane. Correspondingly, a single tissue movement component calculation module can be operated in a time-sharing manner. In FIG. 1, two image forming units 22 and 24 and two tissue movement component calculation units 26 and 28 corresponding to each scanning plane are shown for explaining the invention.

  The first image forming unit 22 and the second image forming unit 24 are configured by a so-called digital scan converter (DSC). This digital scan converter has a coordinate conversion function from a transmission / reception coordinate to a display coordinate, a pixel interpolation calculation function, and the like. That is, the first image forming unit 22 forms a first tomographic image (B-mode image) corresponding to the first scanning plane based on the reception signal corresponding to the first scanning plane. The second image forming unit 24 forms a second tomographic image corresponding to the second scanning surface based on the reception signal corresponding to the second scanning surface. Image data of each tomographic image is output to the display processing unit 30.

  The first tissue movement component calculation unit 26 calculates the movement component of the target tissue on the first scanning plane. Similarly, the second tissue movement component calculation unit 28 calculates the movement component of the target tissue on the second scanning plane. These tissue movement component calculation units 26 and 28 can be configured by hardware or can be realized as a software function.

  Each of the tissue movement component calculation units 26 and 28 has a function of calculating the movement amount of the target tissue in the interframe time by executing a so-called interframe correlation calculation. In this case, the movement amount or the movement component is a parallel movement amount as will be described later with reference to FIG. 6, but a rotational movement amount may be further obtained as shown later in FIG.

  In any case, each of the tissue movement component calculation units 26 and 28 performs a correlation calculation between two frames having different time phases, and preferably between two adjacent frames, whereby the tissue movement component is calculated. Looking for. A specific configuration example will be described later with reference to FIG. The first correlation calculation result 27 and the second correlation calculation result 29 are each output to the three-dimensional movement vector calculation unit 34. In the present embodiment, the first correlation calculation result 27 and the second correlation calculation result 29 are output to the control unit 20 for dynamic variable control of each scanning plane.

  As shown in FIG. 1, in this embodiment, inter-frame correlation calculation is performed using frame data before coordinate conversion. That is, the coordinate system of data input to the tissue movement component calculation units 26 and 28 is a transmission / reception coordinate system (polar coordinate system). For this reason, in this embodiment, the tissue movement component is also expressed as a polar coordinate component, specifically, an r component in the depth direction and a θ or φ component in the angular direction. For dynamic variable control of each scanning plane, the movement component φA in the φ direction on the first scanning plane of the target tissue is used to set the position of the second scanning plane in the first correlation calculation result as will be described later. In the second correlation calculation result 29, the movement component θB in the θ direction of the target tissue on the second scanning plane is used for setting the position of the first scanning plane.

  As described above, in this embodiment, the tissue movement component is obtained using the data before the coordinate conversion. Of course, as shown by reference numerals 23 and 25, the tissue movement component is calculated using the data after the coordinate conversion. It is also possible. In this case, the tissue movement component on each scanning plane is specified as the vertical and horizontal components in the orthogonal coordinate system. Therefore, parameters φA and θB for setting the position of each scanning plane can be obtained by performing coordinate conversion again on the tissue movement component thus identified.

  The display processing unit 30 performs a process of combining a graphic image generated using the graphic image generation function of the control unit 20 with each tomographic image. This will be described later with reference to FIG. The display unit 32 displays a first tomographic image and a second tomographic image obtained by combining the graphic images, respectively.

  The three-dimensional movement vector calculation unit 34 calculates a three-dimensional movement vector of the target tissue based on the first correlation calculation result 27 and the second correlation calculation result 29. This will be described in detail later with reference to FIG. Information of the calculated three-dimensional movement vector is output to the control device 12 as irradiation control information 36. If necessary, the information of the three-dimensional movement vector may be output to the control unit 20 as transmission / reception wave control information 35, and the control unit 20 may control transmission / reception based on such information.

  Here, as described above, the irradiation control information 36 is information representing the three-dimensional movement vector of the target tissue. In this case, several representation methods are conceivable. For example, relative movement vectors (Δx, Δy, Δz) between frames, that is, between time phases may be passed to the control device 12, or the absolute value of the latest target tissue position from the reference target tissue position may be absolute. The deviation amount (x1, y1, z1) may be output. In the above description, the three-dimensional movement vector is represented by orthogonal coordinate expression, but the three-dimensional movement vector may be represented by using polar coordinate expression. That is, relative movement vectors (Δθ, Δφ, Δr) or absolute movement vectors (θ1, φ1, r1) may be used. The three-dimensional movement vector calculation unit 34 calculates a three-dimensional movement vector based on the correlation calculation results 27 and 29 so as to conform to the expression format selected from the plurality of expression formats as described above.

  The control device 12 performs operation control of the irradiation device 14 based on the irradiation control information 36 as described above. In the first control mode, it is determined whether or not the three-dimensional movement vector represented by the irradiation control information 36 or the three-dimensional position of the target tissue represented by the irradiation control information 36 is within the allowable range. Control is performed to allow radiation irradiation, and to stop radiation irradiation when it is outside the allowable range. In the second control mode, the direction of radiation irradiation is controlled based on the irradiation control information 36. In any of the control modes, the problem that the normal tissue is irradiated with radiation as a result of the movement of the target tissue can be avoided in advance, and the therapeutic effect and safety can be improved.

  A three-dimensional space 40 is shown in FIG. A target tissue 42 is represented in the three-dimensional space 40. Examples of the target tissue 42 include a malignant tumor. In one time phase, the target tissue exists at a position indicated by reference numeral 42 ′, and in another time phase, the target tissue exists at a position indicated by reference numeral 42. In this case, a three-dimensional tissue movement vector denoted by reference numeral 44 represents the deviation of the center position of the target tissue.

  In order to obtain the three-dimensional tissue movement vector 44, if volume data is acquired by transmitting and receiving ultrasonic waves for the entire three-dimensional space 40 for each time phase, the so-called volume rate becomes extremely low. In addition, since the calculation of the three-dimensional tissue movement vector 44 is complicated, it is extremely difficult to obtain the three-dimensional tissue movement vector 44 in real time. In the radiotherapy system, it is necessary to monitor the movement of the target tissue in real time during continuous irradiation of radiation, and if the entire three-dimensional space 40 as shown in FIG. Real-time processing becomes difficult in terms of both transmission / reception time and calculation time.

  On the other hand, in the present embodiment, a three-dimensional movement vector is quickly obtained by obtaining a movement component of the target tissue for each scanning plane using a so-called biplane and integrating them.

  FIG. 3 schematically shows the probe 16. The lower surface of the probe 16 is a transmission / reception surface. A 2D array transducer 46 is arranged in the probe 16 along the transmission / reception surface. If a three-dimensional three-dimensional data capture space as indicated by reference numeral 48 is formed using the 2D array transducer 46, the problem shown in FIG. 2 occurs. In the present embodiment, a biplane as indicated by reference signs A and B is formed, thereby improving the frame rate and speeding up the calculation time of the three-dimensional movement vector. The biplane includes a first scanning plane A and a second scanning plane B. The first scanning plane A is formed by scanning an ultrasonic beam in the θ direction. In this case, the position of the first scanning plane A in the φ direction is φA. The second scanning plane D is formed by scanning an ultrasonic beam in the φ direction, and the position of the second scanning plane B in the θ direction is θB. As described above, the positions of the scanning planes A and B can be initialized by the user or automatically, and can be automatically variably set as necessary after that.

  As shown in FIG. 3, when the moving component of the target tissue in the θ direction on the first scanning plane A is obtained, it corresponds to the position change amount of the second scanning plane B in the θ direction. Further, when the movement component in the φ direction of the target tissue is obtained on the second scanning plane B, it corresponds to the position change amount in the φ direction with respect to the first scanning plane A.

  FIG. 4 shows an installation example of the probe 16. In the example shown in FIG. 4, the central axis of the probe 16 is set to be horizontal, and ultrasonic waves are transmitted and received from the side surface of the living body 56. The probe 16 is fixedly held by a probe holding mechanism 50. The probe holding mechanism 50 includes a holder 52 that clamps the proximal end side of the probe 16 and a column 54 that spatially holds the holder 52 at a desired position. Of course, various mechanisms can be used as the probe holding mechanism 50.

  As shown in FIG. 4, the above-described biplane is formed by the probe 16. In the example shown in FIG. 4, the first scanning plane A is formed as a vertical plane, and the second scanning plane B is formed as a horizontal plane. However, the positional relationship between the scanning surfaces is not limited to that shown in FIG. That is, the position of each scanning plane is appropriately set so that the intersecting line of each scanning plane penetrates the target tissue.

  In order to fill distilled water or the like as a coupling medium between the living body 56 and the wave transmitting / receiving surface which is the distal end surface of the probe 16, a water bag 60 is disposed on the side surface of the living body 56 as shown in FIG. The wave transmitting / receiving surface of the probe 16 faces the water bag 60, and the coupling liquid is filled between the wave transmitting / receiving surface and the surface of the living body 56. Since the water bag 60 is deformable itself, a coupling medium is always interposed on the ultrasonic wave propagation path even if the living body moves slightly due to respiration or body position change as indicated by reference numerals 56 and 56 '. That is, there is an advantage that a good ultrasonic wave propagation path can always be secured. Therefore, it is possible to avoid the problem that the measurement of the three-dimensional tissue movement vector cannot be performed due to the movement of the living body. In addition, since the water bag 60 is a highly elastic member, there is an advantage that it is possible to significantly reduce the sense of discomfort or pain compared to the case where the hard member is pressed against the living body 56. There is also an advantage that psychologically it does not give a sense of pressure to the living body. Therefore, if the water bag 60 is used, many clinical advantages can be obtained with a very simple configuration.

  FIG. 5 shows a display example on the display unit 32 shown in FIG. Incidentally, the display screen as shown in FIG. 5 may be displayed on the ultrasonic diagnostic apparatus, or may be displayed on the control apparatus 12 separately or together with it. It is also possible to cause the control device 12 to form and combine a graphic image to be combined with the above-described ultrasonic image.

  Two tomographic images are displayed on the display screen 62. That is, the first tomographic image 64 and the second tomographic image 66. The first tomographic image 64 is a B-mode image corresponding to the first scanning plane, and the second tomographic image 66 is a B-mode image corresponding to the second scanning plane. Each tomographic image 64, 66 represents a cross section of the target tissue T.

  As described above, the first graphic image is synthesized and displayed on the first tomographic image 64. The first graphic image includes an aiming position marker C1 indicating the aiming position on the first scanning plane, and the first scanning plane on the first scanning plane. A line marker L1 representing the second scanning plane, an area marker R1 representing an area to be subjected to correlation calculation described later, and the like are included. Similarly, the second graphic image synthesized and displayed on the second tomographic image 66 also represents the aiming position marker C2 representing the aiming position on the second scanning plane, and the position of the first scanning plane on the second scanning plane. A second line marker L2, an area marker R2 representing an area for correlation calculation on the second scanning plane, and the like are included.

  Therefore, according to the display content as shown in FIG. 5, the spatial form of the target tissue C can be observed by comprehensively observing the two tomographic images, and the positional relationship between the target tissue and each scanning plane. There is an advantage that can be recognized intuitively. Furthermore, the aiming position can be confirmed from different angles in relation to the target tissue. In addition, it is possible to confirm the part that is the target of the correlation calculation.

  The shape of the areas R1 and R2 to be subjected to correlation calculation is illustrated as a quadrangle in FIG. 5, but of course the shape may be, for example, a circle or a trapezoid. In particular, a region specified by a constant width in the θ or φ direction and a constant width in the r direction may be determined as a target for correlation calculation.

  The tissue movement component on each scanning plane will be described with reference to FIGS. FIG. 6 shows the first scanning plane A. Of course, it may be the second scanning plane B. The same applies to FIG. The first scanning plane A includes the target tissue 70. As indicated by reference numerals 70 and 72 from one time phase to the next time phase, the target tissue moves in parallel. The amount of parallel movement in this case is indicated by reference numeral 74. Such a parallel movement amount 74 is defined by the movement direction and the movement amount of the center position, the gravity center position, or other reference position of the target tissue 70. Generally, if such a parallel movement amount is obtained for each frame, it is possible to obtain radiation irradiation control information in real time. However, the movement component of the tissue includes a rotational movement in addition to the parallel movement, which will be described with reference to FIG.

  In FIG. 7, on the first scanning plane A, the target tissue 78 in another time phase is rotated by the amount of rotational movement indicated by reference numeral 80 with respect to the target tissue 76 in one time phase. If the method of frame correlation calculation described later is used, the rotational movement amount shown in FIG. 7 can be obtained by calculation in addition to the parallel movement amount shown in FIG. For example, the shape of the target tissue has a special shape, and the X-ray beam is irradiated only from a specific direction in relation to the thickness of the radiation beam, or the radiation beam is changed according to the size in the direction orthogonal to the beam axis of the target tissue. When adjusting the cross-sectional size, it is desirable to obtain the rotational movement amount shown in FIG.

  In general, when a biplane is formed, the frame rate can be made extremely high, that is, the frame interval on each of the first scanning plane and the second scanning plane is very small. Therefore, since the movement of the target tissue is not so large in the minute time interval, it is desirable to limit the range of the correlation calculation to a certain range when obtaining either the parallel movement amount or the rotational movement amount.

  FIG. 8 shows the concept of inter-frame correlation calculation according to the present embodiment. A reference area 86 is set for the first scanning plane, that is, the first frame data 82. The reference area 86 can be set by the user or automatically, and the reference area 86 can be set fixedly or dynamically.

  The reference area 86 is usually set to include the target tissue. Then, the data in the reference area 86 is cut out from the first frame data 82. This is represented as reference area data 92.

  On the other hand, for the second frame data 84 acquired at a time phase different from that of the first frame data 82, a search area 90 having a certain spread around the reference area is set. An area corresponding to the reference area on the second frame data 84 is represented by reference numeral 86 ′. A corresponding area 88 is set in the search area 90, and the position of the corresponding area 88 is shifted each time the correlation calculation is performed. That is, the position of the corresponding area 88 is sequentially changed so that the entire search area 90 is scanned. Corresponding area data 94 is obtained by cutting out the data in the corresponding area 88 from the second frame data 84.

  A difference calculation is executed for each pixel between the reference area data 92 and the corresponding area data 94, the difference values for each pixel are integrated, and the integrated value is used as a correlation value. This is represented by reference numeral 96. When the correlation calculation is executed for each shift position of the corresponding area 88, the integrated value as the correlation value is associated with each shift position of each corresponding area 88, and thereby the result table 98 is configured. When the result table 98 is completed, the minimum value is determined from a plurality of integrated values as indicated by reference numeral 100. Then, as indicated by reference numeral 102, the tissue translational component is specified from the shift position corresponding to the integrated value as the minimum value.

  FIG. 8 shows the correlation calculation for obtaining the parallel movement amount, but basically the same method is used for the correlation calculation when obtaining the rotational movement amount. That is, the corresponding area 88 is shifted in the rotation direction with respect to the reference area 86, and the correlation calculation is executed at each shift position.

  According to the method shown in FIG. 8, there is an advantage that the tissue movement component can be specified by a simple method of difference calculation and integration processing without performing complicated calculation processing when general correlation calculation is performed. Of course, other methods can be used as a method of correlation calculation between frames, and for example, a method using a general convolution operation may be used. In any case, the moving component of the tissue can be obtained from the shift position when the reference area data 92 and the corresponding area data 94 are most matched.

  FIG. 9 shows a specific configuration example of the first tissue movement component calculation unit 26. As described above, when the second tissue movement component calculation unit 28 is provided separately, the same configuration as that shown in FIG. 9 is used.

  The frame memory unit 104 includes two frame memories 106 and 108 in the example shown in FIG. The first frame memory 106 stores the latest time phase frame data, and the second frame memory 108 stores the previous time phase frame data. That is, necessary frame data is stored on the frame memory unit 104 in order to perform correlation calculation between adjacent frame data. Incidentally, the reference initial frame data is stored in the first frame memory 106, the currently acquired frame data is stored in the second frame memory 108 as indicated by reference numeral 109, and the reference frame and the latest frame are not stored between adjacent frames. It is also possible to perform a correlation calculation between the two.

  The read controller unit 110 is configured by two read controllers in the example shown in FIG. 9, specifically, a reference area data read controller 112 that performs read control of the first frame memory 106 and a read control of the second frame memory 108. And a corresponding area data read controller 114 for performing the above.

  The reference area data read controller 112 performs control to read the reference area data 92 corresponding to the reference area 86 from the first frame data 82 as shown in FIG. The corresponding area data read controller 114 shifts the corresponding area for each correlation calculation from the second frame data stored in the second frame memory 108. Control for reading the corresponding area data 94 corresponding to the corresponding area 88 is executed.

  Each read area data is input to the differentiator 116. The difference unit 116 calculates a difference value for each pixel as described with reference to FIG. Incidentally, the reference area and the corresponding area have the same size. The accumulator 118 accumulates the difference values for each pixel, thereby obtaining an accumulated value as a correlation value. The calculated integrated value is stored in the integrated value memory 120. In other words, the integrated value memory 120 stores data corresponding to the result table 98 shown in FIG. When the position of the corresponding area is sequentially shifted, the integrated values are sequentially calculated and stored in the integrated value memory 120 accordingly.

  The minimum value determiner 122 refers to the content on the integrated value memory 120 at the stage where the scan of the corresponding area is completed, and determines the minimum value from a plurality of integrated values. Then, the tissue movement component is specified based on the shift position of the corresponding area associated with the minimum value. That is, the shift position corresponding to the minimum value corresponds to the parallel movement amount of the target tissue.

  FIG. 10 conceptually shows the calculation contents of the three-dimensional movement vector calculation unit 34 shown in FIG. Here, XYZ represents an absolute three-dimensional space. Xyz represents a relative three-dimensional space defined by the first scanning plane and the second scanning plane. T represents the target position (center position). The vector dM represents the amount of movement of the target tissue, that is, the three-dimensional tissue movement vector between frames, that is, within the period of forming the biplane (note that the arrow symbols representing the vectors are omitted in this specification). Is represented in FIG. 10). The vector T0 is a position vector that represents the position T of the target tissue, and the vector T1 is a position vector that represents the position of the target tissue after movement.

  When the three-dimensional tissue movement vector dM is observed on the first scanning plane A, it is represented by a component dAx in the x direction and a component dAy in the y direction. On the other hand, when the three-dimensional tissue movement vector dM is observed on the second scanning plane B, it is represented by a component dBz in the z direction and a component dBy in the y direction.

Since the y axis is common to the two scanning planes, the following relationship is established.
dAy = dBy (1)

Therefore, the three-dimensional tissue movement vector is expressed as follows.
dM = dAx + dAy + dBz (2)

  Incidentally, in the first control mode, radiation irradiation is controlled to be turned on / off. In this case, when | dM | ≦ ε is satisfied, radiation irradiation is turned on, whereas | dM |> When ε, radiation irradiation is turned off. In other words, if ε is the allowable range of the three-dimensional movement vector or the movement amount of the target tissue based on it, radiation irradiation is allowed only within the allowable range, and radiation irradiation is stopped when it is outside the allowable range. To do.

In the second control mode, the aiming position of the radiation is tracked and controlled as the target tissue moves.
T1 = T0 + TM (3)
Thus, new positions of the target tissue are sequentially specified, and irradiation control is performed so that the aiming position of the radiation matches the position. Incidentally, in such a case, the transmission / reception wave is controlled so that the intersection position of the two scanning planes also matches the aiming position.

  In the above description, the three-dimensional parallel movement amount of the target tissue is calculated, but in addition to such a three-dimensional parallel movement amount, a three-dimensional rotational movement amount can also be calculated. It is. This will be described with reference to the flowchart shown in FIG.

  In FIG. 11, in S101, a reference area is set on the first frame data, that is, the first scanning plane. In S102, a search area is set on the second frame data, that is, the second scanning plane, based on the position of the reference area. In S103, a corresponding area is set at an initial position in the search area.

  In S104, the correlation calculation described above is performed between the reference area data cut out from the reference area and the corresponding area data cut out from the corresponding area. Then, an integrated value that is a result value of the correlation calculation is stored in the memory.

  In S105, it is determined whether or not the corresponding area has reached the final position. If the corresponding area has not been reached, the position of the corresponding area is translated by one step in S106, and the processes after S104 are repeatedly executed. When the position of the corresponding area has reached the final position, the parallel movement amount is specified from the first correlation calculation result in S107. Then, the search area for obtaining the rotational movement amount around the coordinates specified based on the parallel movement amount is reset. In this case, the search area is set within a predetermined angle range in which the orientation of the reference area is 0 degrees as the center.

  In S108, the corresponding area is rotated by one step, and in S109, correlation calculation is performed between the reference area data and the corresponding area data. The correlation calculation result is stored in the memory. In S110, it is determined whether or not the position of the corresponding area has reached the final position. If not, each step of S108 is executed.

  When the final position is reached, in S111, the rotational movement amount is specified from the correlation calculation result obtained by repeatedly executing S109. If necessary, the parallel movement amount may be finely corrected while sequentially setting the corresponding area again in consideration of the rotational movement amount.

  The process shown in FIG. 11 is executed on each of the first scan plane and the second scan plane. As a result, the parallel movement amount and the rotational movement amount are specified for each scanning plane. By combining these movement amounts, a parallel movement amount and a rotational movement amount as a three-dimensional movement vector are specified.

  Next, the radiation therapy system according to the present embodiment will be described with reference to FIGS.

  FIG. 12 conceptually shows a radiotherapy system for treating a malignant tumor or the like using a proton beam. This radiotherapy system includes the three-dimensional tissue movement measurement device 10, the control device 12, and the radiotherapy device 14A. The three-dimensional tissue movement measuring apparatus 10 has the configuration shown in FIG. That is, the three-dimensional tissue movement measuring apparatus 10 is configured as an ultrasonic diagnostic apparatus, which is roughly configured by the apparatus main body 132 and the probe 16. A living body 130 is placed on the treatment table 58. In that case, the irradiation position of the proton beam 134 is positioned with respect to the target tissue T. Usually, the irradiation position of the proton beam 134 is fixedly set, and the proton beam 134 is positioned with respect to the target tissue T by horizontally moving the treatment table 58. As described above, the state of the target tissue T is measured by an ultrasonic diagnostic apparatus using a biplane, and the three-dimensional tissue movement vector of the target tissue T is measured by the apparatus main body 32. This is passed to the control device 12 as irradiation control information.

  The control device 12 determines whether or not the three-dimensional tissue movement vector or the position of the target tissue based on the three-dimensional tissue movement vector is within an allowable range, and if it is within the allowable range, outputs an irradiation permission signal to the radiotherapy device 14A. If it is outside the allowable range, an irradiation prohibition signal is output to the radiation therapy apparatus 14A.

  Accordingly, when the posture of the living body 130 is changed, or when the position of the target tissue T is changed due to breathing or the like, and when the target tissue T is out of the allowable range, radiation irradiation is stopped. There is an advantage that it is possible to avoid the irradiation of radiation. In addition, when the target tissue T periodically moves due to breathing or the like, the target tissue T can be irradiated with the proton beam 134 periodically or intermittently, thereby increasing the therapeutic effect. .

  FIG. 13 conceptually shows the overall configuration of a radiation therapy system according to another embodiment. This radiotherapy system includes the three-dimensional tissue movement measurement device 10, the control device 12, and the radiotherapy device 14B, as in the embodiment shown in FIG. However, the radiotherapy device 14B is a device that performs treatment by X-rays.

  The three-dimensional tissue movement position measuring apparatus 10 has an ultrasonic diagnostic apparatus main body 132 and a probe 16 as in the above-described embodiment, and the probe 16 is held by a holding mechanism 50 as shown in FIG. . The ultrasonic diagnostic apparatus main body 132 calculates a three-dimensional tissue movement vector for the target tissue, and passes it to the control apparatus 12 as irradiation control information. The controller 12 outputs irradiation position control information to the radiation therapy apparatus 14B.

  The radiotherapy apparatus 14 </ b> B has an X-ray irradiation unit 136, and the X-ray irradiation unit 136 can rotate so as to surround the treatment table 58. The treatment table 58 is movable in the horizontal direction. Therefore, when the target tissue moves, the irradiation point can always be matched with the target tissue by performing parallel movement of the treatment table 58 or the like.

  FIG. 14 shows a living body 130 as a patient placed on a treatment table. By rotating the X-ray irradiation unit 136 as indicated by reference numeral 142, each angle with respect to the target tissue T is shown. The X-ray beam 140 can be irradiated from the direction. In this case, the irradiation point can be matched with the target tissue T by moving the treatment table in parallel.

  In this embodiment, since the movement position of the target tissue can be measured in real time, it is possible to dynamically change the X-ray irradiation position by following the movement of the target tissue. In this case, it is desirable to variably control the first scanning plane and the second scanning plane in accordance with the movement of the target tissue. Of course, in the configuration shown in FIGS. 13 and 14, when the movement position of the target tissue is out of the allowable range, control for stopping the X-ray irradiation may be performed.

  According to each of the above-described embodiments, it is possible to measure the position of the target tissue in real time and perform irradiation control of the therapeutic radiation based on the measured position, so that the treatment effect can be enhanced and the damage given to the normal tissue There is an advantage that can be avoided as much as possible. In the above embodiment, the 2D array transducer is provided on the probe. However, a probe of a type that scans the 1D array transducer by a mechanical mechanism may be used, or two 1Ds arranged in a cross shape may be used. An array transducer may be provided and the posture of the probe itself having the transducer may be changed.

  For example, when the volume data is composed of 60 frame data, in the present embodiment, two frames are required in comparison with the case where 60 frame data must be acquired every time in order to obtain a three-dimensional tissue movement vector. Since the three-dimensional tissue movement vector can be obtained every time data is acquired, the calculation speed can be increased, for example, by 30 times compared to the case of acquiring volume data.

  Further, according to the above embodiment, as shown in FIG. 4, it is possible to always ensure good propagation of ultrasonic waves regardless of the movement of the living body using the water bag 60. There is an advantage that interruption can be avoided and problems such as discomfort and pain to the living body can be avoided. In the above embodiment, since the difference calculation is used, there is an advantage that the correlation calculation result can be obtained quickly with a very simple configuration. In the above embodiment, since the tissue movement component is calculated using data before coordinate conversion, there is an advantage that the calculation result can be used as it is for setting the position of the scanning plane. That is, it is possible to quickly set the position of the scanning plane without performing complicated coordinate conversion processing on the correlation calculation result.

  Incidentally, the ultrasonic diagnostic apparatus as the three-dimensional tissue movement measuring apparatus 10 shown in FIG. 1 can be used alone as well as used in a radiation therapy system. In other words, when observing a tissue in two orthogonal cross sections using a biplane, there is an advantage that a good tomographic image of the affected area can always be obtained if the position of each scanning plane is dynamically changed following the movement of the tissue. . Therefore, it is useful also in general ultrasonic diagnosis. It is also possible to automatically set the puncture direction and the like based on the three-dimensional tissue movement vector, and the point for focusing the ultrasonic wave in a calculus crushing system etc. can be changed dynamically according to the three-dimensional tissue movement vector. You may make it do. Other than that, various application examples can be considered. Incidentally, although two orthogonal scanning planes are formed in the above-described embodiment, three or four scanning planes that cross each other may be formed as necessary. From the viewpoint of rapid measurement and high-speed computation, it is most desirable to form a biplane.

It is a block diagram which shows the structure of the ultrasonic diagnosing device as a three-dimensional tissue movement measuring device which concerns on this embodiment. It is a figure for demonstrating the three-dimensional movement of the target structure | tissue in three-dimensional space. It is a figure which shows a probe and the biplane formed by it. It is a figure which shows the state which installed the probe with respect to the biological body. It is a figure which shows two tomographic images displayed on a display screen. It is a figure for demonstrating the amount of parallel movement of the target structure | tissue on a scanning surface. It is a figure for demonstrating the amount of rotational movement of the target structure | tissue on a scanning surface. It is a conceptual diagram for demonstrating an example of a correlation calculation. It is a block diagram which shows the specific structural example of the tissue movement component calculating part shown in FIG. It is a conceptual diagram for demonstrating the calculation principle of a three-dimensional tissue movement vector. It is a flowchart which shows the operation example in the case of calculating a rotational movement amount in addition to a parallel movement amount as a three-dimensional tissue movement vector. It is a conceptual diagram which shows the whole structure of the radiotherapy system which treats with a proton beam. It is a conceptual diagram which shows the whole structure of the radiotherapy system which treats by X-ray. It is a figure which shows the concept in the case of rotating an X-ray beam in the radiotherapy system shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 3D tissue movement measuring device (ultrasound diagnostic device), 12 control device, 14 irradiation device (radiotherapy device), 16 probe, 18 transmitting / receiving unit, 20 control unit, 22 first image forming unit, 24 second image forming 26, first tissue movement component calculation unit, 28 second tissue movement component calculation unit, 30 display processing unit, 34 three-dimensional movement vector calculation unit, 82 first frame data, 84 second frame data, 86 reference area, 88 Improved area, 90 search area, 92 reference area data, 94 corresponding area data, 104 frame memory section, 110 read controller section, 116 differentiator, 118 accumulator, 120 accumulated value (memory), 122 minimum value determiner.

Claims (5)

A radiotherapy apparatus for irradiating a target tissue in a living body with radiation;
A three-dimensional tissue movement measuring device for measuring a three-dimensional tissue movement vector in real time for the target tissue;
An irradiation control device for controlling the irradiation of the radiation;
In a radiation therapy system including:
The three-dimensional tissue movement measuring device is
Having a two-dimensional array transducer, the first and second scan planes that are orthogonal to each other are repeatedly formed by transmitting and receiving ultrasonic waves by the two-dimensional array transducer, and frame data for each scan plane is obtained. Transmitting / receiving means for sequentially outputting;
Correlation calculating means for performing a correlation calculation between two frame data having different time phases for each scanning plane;
A three-dimensional tissue movement vector calculating means for calculating a three-dimensional tissue movement vector based on the result of the correlation calculation for each scanning plane;
Including
The irradiation control device variably controls the radiation aim position based on the three-dimensional tissue movement vector in the aim position variable mode ,
In the three-dimensional tissue movement measurement apparatus, in the aiming position variable mode, the first scanning plane and the first scanning plane and the second scanning plane are positioned such that the radiation aiming position is positioned on an intersection line of the first scanning plane and the second scanning plane. Scanning control means for electronically variably setting the position of the second scanning plane;
A radiation therapy system characterized by that. The system of claim 1, wherein
The radiation control system , wherein, in the aiming position fixing mode, the radiation treatment system limits the radiation irradiation when the three-dimensional tissue movement vector or a target tissue position based on the vector moves out of an allowable range. The system of claim 1, wherein
The wave transmitting / receiving means includes
An ultrasonic probe having a pre SL two-dimensional array transducer,
A liquid container that fills an ultrasonic wave propagation path between the transmitting / receiving surface of the ultrasonic probe and the living body surface with a coupling liquid;
A radiation therapy system comprising: The system of claim 1, wherein
The three-dimensional tissue movement measuring apparatus includes an image forming unit that forms a tomographic image based on frame data for each of the first scanning plane and the second scanning plane . The system of claim 4 , wherein
Before SL three-dimensional tissue movement measuring apparatus or the irradiation control unit,
Forming a first graphic image having a first line marker representing a position of the second scan plane on the first scan plane and a first aim position marker representing a radiation aim position on the first scan plane; Graphic image formation for forming a second graphic image having a second line marker representing the position of the first scanning surface on the second scanning surface and a second aiming position marker representing the aiming position of the radiation on the second scanning surface. Means,
A tomographic image corresponding to the first scanning plane and the first graphic image are synthesized to form a first synthesized image, and a tomographic image corresponding to the second scanning plane and the second graphic image are synthesized. Image synthesizing means for forming a second synthesized image;
Display means for displaying the first composite image and the second composite image;
A radiation therapy system comprising:

Images