JP2020028703A - Position measuring device, position measuring method, and particle beam irradiation system - Google Patents

Abstract

To measure a target position in a body from an ultrasonic image highly accurately and quickly.SOLUTION: A position measuring device 1 includes: a three-dimensional movement model creation unit 12 for creating a three-dimensional movement model indicating a three-dimensional position of a body tissue according to the respiration; a first ultrasonic sensor group 141 arranged along a first direction in which a target moves in the body according to the respiration; a second ultrasonic sensor group 142 arranged sparsely along a second direction intersecting with the first direction; a position calculation unit 153 for calculating a first position of the target on the basis of a first ultrasonic image acquired from signals, etc. of the first ultrasonic sensor group; a position calculation unit 155 for calculating a second position of the target by comparing a second ultrasonic image acquired from signals, etc. of the second ultrasonic sensor group and the three-dimensional movement model; and a target three-dimensional position computing unit 156 for calculating a three-dimensional position of the target in the body from the first position and the second position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a position measuring device, a position measuring method, and a particle beam irradiation system.

  Radiation therapy is known as one of the treatment methods for cancer. Radiation therapy is a method of treating a patient by irradiating a high dose of radiation to a body tissue to be treated by a patient. In radiotherapy, side effects are relatively light because radiation can be focused on the target to be treated. In order to efficiently carry out radiation therapy, it is important that the position of the region where the radiation is intensively irradiated and the position of the region where the cancer tumor is present coincide with high accuracy.

  In a conventional radiation therapy apparatus, the position of a body tissue which is a treatment target site is specified from information of a CT (Computed Tomography) image acquired in advance, and a treatment plan is made based on the specified position. In the related art, characteristics such as the direction and intensity of radiation to be irradiated on a patient are controlled in accordance with a treatment plan.

  However, if the patient breathes during the irradiation of radiation, the treatment target site fluctuates from the radiation irradiation position planned in advance, and accurate treatment becomes difficult. Therefore, a gold marker is embedded in the patient's body, and the position of the marker is imaged and tracked by an X-ray transmission image. By detecting a change in the treatment target site from the position of the marker and using it for a prior treatment plan or radiation control at the time of irradiation, treatment can be performed with high accuracy.

  On the other hand, a method using an ultrasonic image has been proposed in order to measure a target position in a body in response to a patient's movement due to respiration while suppressing the amount of exposure due to X-ray irradiation during treatment (Patent Document 1, 2).

JP-A-2003-117010 Patent No. 4394945

  In Patent Document 1, instead of a marker and an X-ray, a CT image and an ultrasonic image acquired in advance and an ultrasonic image acquired during treatment are compared, and the ultrasonic image acquired in advance and acquired during treatment are compared. Irradiation is performed at a timing when the correlation value with the obtained ultrasonic image is high. However, the technique described in Patent Literature 1 merely irradiates radiation based on a correlation between a previous ultrasonic image and an ultrasonic image during treatment, and does not specify a change in a target position due to respiration. Absent.

  In Patent Literature 2, a three-dimensional movement vector of a body tissue of a patient is output by calculating a correlation between two frame data on each scanning plane using two intersecting two-dimensional ultrasonic images. ing. However, in the method of Patent Literature 2, the target deviates from the scan plane due to the patient's breathing. Furthermore, in Patent Literature 2, since a position is calculated only from an ultrasound image during treatment without using a CT image, an error occurs between an actual tumor position and a measurement position.

  The present invention has been made in view of the above problems, and provides a position measuring device, a position measuring method, and a particle beam irradiation system that can accurately and quickly measure a target position in a body from an ultrasonic image during treatment. The purpose is to provide.

  In order to solve the above-described problems, a position measuring device according to the present invention includes a three-dimensional movement model creating unit that creates a three-dimensional movement model indicating a three-dimensional position of a body tissue according to respiration, and a target that moves inside the body according to breathing. A first ultrasonic sensor group arranged on the body surface along a moving first direction, and a second ultrasonic sensor group arranged on the body surface along a second direction intersecting the first direction, Based on a second ultrasonic sensor group arranged more sparsely than the first ultrasonic sensor group, a first ultrasonic image obtained from a position of the first ultrasonic sensor group and a signal from the first ultrasonic sensor group. A first position calculating unit for calculating a first position of the target; a second ultrasonic image obtained from a position of the second ultrasonic sensor group and a signal from the second ultrasonic sensor group; A second position for calculating a second target position by comparing Comprising a detection section, a target three-dimensional position calculating unit that calculates a three-dimensional position in the body of the target from the first position and the second position.

  According to the present invention, the first position obtained from the first ultrasonic image and the second position obtained from the collation of the three-dimensional movement model indicating the three-dimensional position of the body tissue according to the respiration with the second ultrasonic image Accordingly, the three-dimensional position of the target in the body can be calculated with high accuracy and quickly.

It is an overall schematic diagram of a position measuring device. It is a block diagram of a computer used for realizing a position measuring device. It is a schematic diagram which shows a mode that the target position in a body fluctuates by the respiration during treatment. It is a conceptual diagram of the identification method of the target position which is related technology. It is another conceptual diagram of the method of specifying the target position which is related technology. FIG. 3 is an explanatory diagram illustrating a concept of forming an image from a reception signal of an ultrasonic sensor. FIG. 4 is an explanatory diagram illustrating time domain data of a reception signal of the ultrasonic sensor. FIG. 9 is an explanatory diagram illustrating a state in which an image is obtained using a first ultrasonic sensor group and a second ultrasonic sensor group. FIG. 4 is an explanatory diagram of a three-dimensional movement model showing a three-dimensional position of a body tissue that changes according to respiration. It is an example of a 2nd ultrasonic image. 9 is a flowchart of a process for calculating a target position. FIG. 7 is an overall schematic diagram of a particle beam irradiation system including a position measuring device having a specific structure according to a second embodiment. FIG. 13 is an overall schematic diagram of an ultrasonic therapy apparatus including a position measuring device having a specific structure according to a third embodiment. FIG. 13 is an overall schematic diagram of a position measuring device according to a fourth embodiment. FIG. 13 is an overall schematic diagram of a position measuring device according to a fifth embodiment. It is explanatory drawing which concerns on 5th Example and shows the method of selecting the ultrasonic imaging surface from a three-dimensional volume image, and the selection method of the corresponding sensor element. It is a flow chart of processing which chooses an imaging section and a sensor element concerning a 5th example. FIG. 19 is an explanatory diagram illustrating a method of correcting an ultrasonic image according to the sixth embodiment. FIG. 4 is an explanatory diagram illustrating time domain data of a reception signal of the ultrasonic sensor. FIG. 9 is an explanatory diagram showing a state of correcting a position shift by comparing a three-dimensional movement model with an ultrasonic image. 9 is a flowchart of a process for correcting an ultrasonic image. 15 is a flowchart of a process for calculating a target position according to the seventh embodiment. FIG. 19 is an explanatory diagram of a method for calculating a target position according to the eighth embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a plurality of ultrasonic sensor groups constituting ultrasonic images with different precisions are arranged so as to intersect, and the ultrasonic images obtained from the ultrasonic sensor groups with low precision are supplemented by a three-dimensional movement model. This makes it possible to satisfy the conflicting requirements of highly accurate target position measurement and quick target position measurement.

  That is, the position measuring device according to the present embodiment arranges the first ultrasonic sensor group densely along the moving direction of the target, and sparsely intersects the second ultrasonic sensor group with the first ultrasonic sensor group. It is arranged and an ultrasonic image obtained from the second ultrasonic sensor group is compared with a three-dimensional movement model created in advance. Accordingly, the position measuring device according to the present embodiment is configured such that the first position obtained from the signal of the first ultrasonic sensor group and the second position obtained from the signal of the second ultrasonic sensor group and the three-dimensional movement model are obtained. Based on this, the position of the target in the body can be calculated accurately and in a short time. In the following description, an ultrasonic image is referred to as an ultrasonic image.

  The first embodiment will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing an overall outline of the position measuring device 1.

  The position measuring device 1 is a body tissue position measuring device that measures the position of an affected part of a patient (also referred to as a subject) 2 placed on a bed 3. The affected part is a site to be treated, and corresponds to a “target in the body”.

  The position measuring device 1 can be composed of, for example, one or a plurality of computers. The position measurement device 1 includes, for example, a three-dimensional respiration information acquisition unit 11, a three-dimensional movement model creation device 12, a sensor installation position calculation device 13, an ultrasonic measurement device 14, a target position calculation device 15, a sensor position measurement unit 16, a target A position output unit 17 is provided. In the drawings, “target position output unit” is appropriately described as “output”, and “three-dimensional” is described as “3D”.

  Each of the devices 12, 13, and 15 described below can be configured as a system using independent computers, or can be configured as a function that shares one or more computers. Therefore, “device” can also be called “function”. Further, the arrangement of the functions 11 to 17 is not limited to the example of FIG. One or more functions may be integrated, or conversely, one function may be divided into a plurality of functions. Any configuration can be adopted as long as the object of the present embodiment can be achieved.

  The three-dimensional respiration information acquisition unit 11 has a function of acquiring, from a CT device or the like, three-dimensional respiration information indicating a change in the position of a body tissue accompanying a patient's respiration. The acquired three-dimensional respiration information is input from the three-dimensional respiration information acquisition unit 11 to the three-dimensional movement model creation device 12 and the sensor installation position calculation device 13, respectively.

  The three-dimensional movement model creation device 12 is a device that creates a three-dimensional movement model based on three-dimensional respiration information. The three-dimensional movement model creation device 12 includes, for example, a respiration information storage unit 121, a three-dimensional movement model creation unit 122, and a database 123.

  The respiration information storage unit 121 has a function of acquiring and storing three-dimensional respiration information from the three-dimensional respiration information acquisition unit 11. The three-dimensional movement model creation device 122 has a function of creating a three-dimensional movement model. The database 123 is a function for storing and managing the created three-dimensional movement model. Details of the three-dimensional movement model M1 will be described later with reference to FIG.

  The sensor installation position calculation device 13 is a device that determines the arrangement of the ultrasonic sensor 140 attached to the patient 2. The sensor installation position calculation device 13 includes, for example, a target movement route calculation unit 131 and an installation position calculation unit 132.

  The target movement path calculation unit 131 has a function of calculating a path along which the target moves in the patient based on the three-dimensional respiration information. The installation position calculation device 132 has a function of calculating where on the body surface of the patient 2 the ultrasonic sensor 140 is to be installed.

  The ultrasonic measuring device 14 is a device that measures the state inside the body of the patient 2 using ultrasonic waves and outputs the measurement result. The ultrasonic measuring device 14 includes, for example, an ultrasonic sensor 140 and an ultrasonic transmitting / receiving unit 143.

  The ultrasonic sensor 140 is a sensor that transmits an ultrasonic wave and receives an ultrasonic wave reflected by an object and outputs an electric signal. The ultrasonic sensor 140 includes a first ultrasonic sensor group 141 and a second ultrasonic sensor group 142. As will be described later with reference to FIG. 8, the first ultrasonic sensor group 141 is densely arranged on the body surface of the patient 2 along a main direction in which a target position such as an affected part changes according to respiration. The second ultrasonic sensor group 142 intersects with the first ultrasonic sensor group 141 and is sparsely arranged on the body surface of the patient 2. The first ultrasonic sensor group 141 and the second ultrasonic sensor group 142 are arranged so as to intersect substantially orthogonally (X direction and Y direction in FIG. 8). The first ultrasonic sensor group 141 and the second ultrasonic sensor group 142 may be arranged vertically (X direction and Z direction or Y direction and Z direction in FIG. 8). Here, the sparse or dense sensor number is the sparse or dense in the comparison between the first ultrasonic sensor group 141 and the second ultrasonic sensor group 142. That is, the number of sensors in the second ultrasonic sensor group 142 may be smaller than the number of sensors in the first ultrasonic sensor group 141.

  The ultrasonic transmission / reception unit 143 has a function of transmitting an instruction from the target position calculation device 15 to the ultrasonic sensor 140 and operating the same, and transmitting a signal detected by the ultrasonic sensor 140 to the target position calculation device 15.

  The target position calculation device 15 is a device that calculates a target position in the body of the patient 2 based on a signal received from the ultrasonic measurement device 14 and the three-dimensional movement model created by the three-dimensional movement model creation device 12. is there. The target position calculating device 15 includes, for example, an image forming unit 150, a first target position calculating unit 153, an image matching unit 154, a second target position calculating unit 155, and a target three-dimensional position calculating unit 156.

  The image forming unit 150 has a function of generating an ultrasonic image based on the installation positions of the ultrasonic sensor groups 141 and 142 and detection signals of the ultrasonic sensor groups 141 and 142. The first ultrasonic image forming unit 151 has a function of forming a first ultrasonic image from signals of the first ultrasonic sensor group 141. The second ultrasonic image forming unit 152 has a function of forming a second ultrasonic image from a signal of the second ultrasonic sensor group 142.

  The first target position calculator 153, which is an example of the “first position calculator”, determines the first position as the “first position” from the information on the installation position of the first ultrasonic sensor group 141 and the first ultrasonic image. This function calculates the target position. The image collating unit 154 has a function of collating the second ultrasonic image acquired from the second ultrasonic image forming unit 152 with the three-dimensional movement model acquired from the database 123. The second target position calculation unit 155, which is an example of the “second position calculation unit”, has a function of calculating the second target position as the “second position” from the result of the comparison by the image comparison unit 154. As a result, the second target position calculation unit 155 determines the installation position of the second ultrasonic sensor group 142, the second ultrasonic image, and the collation result of the second ultrasonic image and the three-dimensional movement model. Then, a second target position is calculated.

  The target three-dimensional position calculation unit 156 calculates the position of the target in the body based on the first target position calculated by the first target position calculation unit 153 and the second target position calculated by the second target position calculation unit 155. Is a function for calculating.

  The sensor position measuring unit 16 has a function of measuring a position where the ultrasonic sensor groups 141 and 142 are actually installed, and outputting a measurement result to the target position calculating device 15.

  The target position output unit 17 has a function of outputting a target three-dimensional position which is a calculation result of the target position calculation device 15. By providing the output of the target position output unit 17 to a particle beam therapy system or the like, it is possible to irradiate an accurate position with the particle beam and perform appropriate treatment.

  As described above, the patient 2 has the ultrasonic sensor 140 including the first ultrasonic sensor group 141 and the second ultrasonic sensor group 142 installed on the body surface and fixed on the bed 3. When receiving the electric signal from the ultrasonic transmission / reception unit 143, the ultrasonic sensor 140 transmits the ultrasonic wave to the inside of the patient 2. The ultrasonic sensor 140 receives the ultrasonic wave returned from the body of the patient 2 by reflection or scattering, converts the ultrasonic wave into an electric signal, and transmits the electric signal to the ultrasonic transmission / reception unit 143. The ultrasonic transceiver 143 amplifies the electric signal received from the ultrasonic sensor 140 and sends the amplified electric signal to the image forming unit 150 of the target position calculating device 15.

  Inside the ultrasonic sensor 140, the ultrasonic sensors are arranged in a line. By controlling the excitation timing of each ultrasonic sensor by the ultrasonic transmission / reception unit 143, the focus position of the ultrasonic wave can be scanned. Then, the image forming unit 150 can acquire an ultrasonic image in the ultrasonic scanning range by synthesizing the ultrasonic reception signals received by the ultrasonic transmission / reception unit 143.

  An example of a hardware configuration and a software configuration of the device will be described with reference to FIG. Each of the devices 12, 13, 14, and 15 constituting the position measuring device 1 is realized by using, for example, a computer 10. The computer 10 may be a general-purpose computer or a dedicated control device. Examples of the computer 10 include a personal computer, a controller, a sequencer, and a programmable logic array.

  The computer 10 includes, for example, a microprocessor 101, a memory 102, a communication interface circuit 103, and an input / output circuit 104. In the figure, the microprocessor is described as a CPU (Central Processing Unit), and the communication interface circuit 103 is described as a “communication interface”.

  The memory 102 stores, for example, a computer program Pn and data Dn. The memory 102 is not limited to a semiconductor memory, and may include another storage device such as a hard disk device or an optical disk device. A predetermined function is realized by the microprocessor 101 reading and executing the computer program Pn. The computer program Pn performs a predetermined process using predetermined data Dn. The database 123 and the like can be realized using the memory 102.

  The communication interface circuit 103 is a circuit that communicates with another device via a wireless communication line or a wired communication line (not shown). The input / output circuit 104 is a circuit that receives a signal from another device or outputs a signal to another device. In addition to the configuration shown in FIG. 2, a user interface device (not shown) may be provided. The user interface device includes, for example, an information output device such as a display or a printer, and an information input device (neither is shown) such as a keyboard or a voice input device.

  FIG. 3 is a schematic diagram illustrating a manner in which a target position in a patient's body changes as the patient breathes. In the following description, a change in position is expressed by adding parenthesized numbers to the body surface 21, the target 22, and the like.

  During inspiration, the lungs expand, so that they inflate like the body surface 21 (1). On the other hand, at the time of exhalation, the lungs contract, so that they contract like the body surface 21 (2). Other organs move inside the body while deforming according to the expansion and contraction of the lungs. Therefore, the target 22 in the body also moves in the body like the target 22 (1) and the target 22 (2) in accordance with the breathing.

  A technique related to the position measuring device 1 of the present embodiment will be described with reference to FIGS. FIG. 4 shows a method for detecting the position of the target 22 inside the patient using X-rays. FIG. 5 shows a method for detecting the position of the target 22 in the patient using ultrasonic waves. 4 and 5 are referred to for understanding the present embodiment.

  In the X-ray transmission image system shown in FIG. 3, the position of the tumor is constantly monitored when the patient is irradiated with the radiation 51. The target 22 in the body and the marker 41 buried near the target 22 change positions according to breathing. In the X-ray transmission image method, an X-ray tube 43 irradiates a region including the gold marker 41 with X-rays to obtain an X-ray transmission image 43. From the X-ray transmission image 43, the position of the marker 41 can be calculated.

  In the ultrasonic method shown in FIG. 5, for example, an ultrasonic cross-sectional image 62 is obtained by pressing a hand-held ultrasonic sensor 61 against the body surface 21 of a patient. From the image of the in-vivo target 22 included in the ultrasound image 62, the position of the target 22 can be calculated. Here, since the position of the target 22 fluctuates due to breathing, there is a possibility that the target 22 deviates from the ultrasonic section 62. Therefore, a tumor position is grasped by acquiring a three-dimensional volume image.

  A method for constructing an ultrasonic image of the target 22 in the body will be described with reference to FIG. Here, for convenience, the description will be made assuming that four sensors 1411 (1) to (4) are attached to the body surface 21 of the patient.

  The ultrasonic wave transmitted from the ultrasonic sensor 1411 (1) travels in the body, collides with the target 22 in the organ 23, and generates a reflected wave or a scattered wave. These reflected waves are received by another ultrasonic sensor 1411 (4). Reference numeral 24 denotes a spine.

  The reception signal of the ultrasonic sensor group will be described with reference to FIG. On the left side of FIG. 7, the signal of the first ultrasonic sensor group 141 is shown as time domain data. Similarly, the signal of the second ultrasonic sensor group 142 is shown as time domain data on the right side of FIG. The suffix “n” of “Φnm” in the figure is the number of the sensor that emits the ultrasonic wave. The suffix “m” is the number of a sensor that receives the ultrasonic wave reflected by an organ or the like.

  The propagation distance of the ultrasonic sensor corresponds to the propagation time t of the ultrasonic wave. The signal of the ultrasonic sensor is obtained as time domain data. By arranging these signals according to the position of the ultrasonic sensor, an ultrasonic image can be obtained. At this time, based on the preset recording time T, time domain data separated by a certain time is obtained. According to the number of ultrasonic sensors, an ultrasonic transmission / reception time for rendering one ultrasonic image is determined.

  To acquire a three-dimensional volume image, it is necessary to arrange the ultrasonic sensors two-dimensionally. As the number of ultrasonic sensors increases, the recording time of the signal increases. Further, as the amount of data received from the ultrasonic sensor increases, the amount of calculation for forming a three-dimensional volume image also increases. Therefore, when a three-dimensional volume image is used, it is difficult to calculate a target position following a position change due to breathing.

  FIG. 8 is a conceptual explanatory diagram of an ultrasonic image used by the position measuring device 1. As described above, it is difficult to calculate a target position in real time using a three-dimensional volume image. Therefore, the position measurement device 1 of the present embodiment acquires and stores in advance the three-dimensional movement information (three-dimensional respiration information) of the target due to respiration.

  As shown in the upper part of FIG. 8, the position measurement device 1 arranges the ultrasonic sensor groups 141 and 142 on the body surface 21 of the patient 2 using the three-dimensional respiration information. That is, the first ultrasonic sensor group 141 is densely arranged in the direction X in which the target 22 mainly moves, and the second ultrasonic sensor group 142 is sparsely arranged in the direction Y orthogonal to the main moving direction X.

  The position measuring device 1 includes signals from the ultrasonic sensor groups 141 and 142 arranged at different densities in two intersecting directions X and Y, installation positions of the ultrasonic sensor groups 141 and 142, and three-dimensional respiration information. The three-dimensional position of the target 22 is calculated almost in real time from the three-dimensional movement model obtained from.

  That is, in the present embodiment, the first ultrasonic sensor group 141 densely arranged in the main movement direction X is used, and the first ultrasonic sensor group 141 is used in the direction Y intersecting the main movement direction X. The sparsely arranged second ultrasonic sensor group 142 is used. In this embodiment, by using as many ultrasonic sensors as necessary for calculating the three-dimensional position, the amount of data and the amount of calculation can be reduced, and the target position can be calculated at high speed.

  The ultrasonic images generated by the first ultrasonic sensor group 141 and the second ultrasonic sensor group 142 include a first ultrasonic image G1 shown in the lower left of FIG. 8 and a second ultrasonic image G2 shown in the lower right of FIG. Is obtained as follows.

  Since the first ultrasonic sensor group 141 is densely arranged along the main direction X in which the target moves by breathing, the first ultrasonic sensor group 141 is based on the first ultrasonic image G1 generated by the signal of the first ultrasonic sensor group 141. Thus, the target position can be calculated with high accuracy.

  Since the second ultrasonic sensor group 142 is sparsely arranged along the direction Y intersecting (perpendicular to) the main movement direction X due to respiration, the second ultrasonic sensor group 142 is generated by a signal of the second ultrasonic sensor group 142. The accuracy of the ultrasonic image G2 may be coarse. Therefore, the position measurement device 1 calculates the target position by comparing the three-dimensional movement model with the second ultrasonic image G2. Therefore, the position measuring device 1 of the present embodiment can calculate the target position with high accuracy and high speed while reducing the data amount of the ultrasonic sensor groups 141 and 142.

  Please refer to FIG. The three-dimensional respiration information acquisition unit 11 captures, for example, a CT image or an MRI (Magnetic Resonance Imaging) image including at least a body tissue to be subjected to position calculation at a timing synchronized with respiration. By capturing a CT image or an MRI image at a plurality of timings for each respiratory phase, the internal tissue position and other tissues of the patient for each respiratory phase are acquired as three-dimensional information.

  Here, the ultrasonic sensor 140 may create a CT image or MRI image artifact. In this case, only at the time of acquiring the three-dimensional respiration information, a dummy sensor with less artifact may be used instead of the ultrasonic sensor 140 to simulate the pressing of the body surface by the ultrasonic sensor 140. The three-dimensional respiration information acquired by the three-dimensional respiration information acquisition unit 11 is sent to the respiration information storage unit 121 and stored.

  FIG. 9 is an example of a three-dimensional movement model. The three-dimensional movement model creation device 12 creates the three-dimensional movement model M1 in accordance with the three-dimensional respiration information on the respiration of the patient 2 stored in the respiration information storage unit 121. The three-dimensional movement model M1 is information indicating a state in which the body tissue of the patient 2 moves by respiration, and is divided into appropriate small regions (mesh).

  The sensor installation position calculation device 13 determines the installation position of the ultrasonic sensor groups 141 and 142 based on the three-dimensional respiration information of the patient. In the position measuring device 1, it is determined which cross section of the three-dimensional moving model to obtain an ultrasonic cross-sectional image based on the installation position of the ultrasonic sensor 140 (the ultrasonic sensor groups 141 and 142). The range information of the comparison area between the three-dimensional movement model M1 and the cross-sectional image obtained from the actual ultrasonic image and the three-dimensional movement model M1 is stored in the database 123.

  The sensor installation position calculation device 13 uses the target movement path calculation unit 131 to calculate the movement path of the target 22 from the three-dimensional respiration information. The sensor installation position calculation unit 132 of the sensor installation position calculation device 13 calculates the installation position of the ultrasonic sensor 140 so that the target always exists in the cross section of the ultrasonic sensor 140.

  The image forming unit 150 of the target position calculating device 15 forms an ultrasonic image from the ultrasonic reception signal acquired by the ultrasonic sensor 140 and the sensor position measured by the sensor position measuring unit 16. The image collating unit 154 of the target position calculating device 15 refers to the ultrasonic image acquired in real time, the image data of the three-dimensional movement model stored in the database 123, and the range information of the comparison region, to thereby obtain the actual ultrasonic image. The image is compared with the image obtained from the three-dimensional movement model.

  The sensor position measurement unit 16 is configured to include a position sensor such as an optical sensor, a magnetic sensor, and an ultrasonic sensor. The sensor position measurement unit 16 measures the actual position of the ultrasonic sensor 140 in synchronization with the collection of the ultrasonic signal by the ultrasonic measurement device 14. It does not matter what method the sensor position measuring unit 16 measures the position of the ultrasonic sensor 140.

  As described in FIG. 9, the position of the target 22 in the body of the patient 2 can be calculated by comparing the actual ultrasonic image with the three-dimensional movement model. The image matching unit 154 matches the pixel size of the cross-sectional image M11 in a specific cross section of the three-dimensional movement model M1 illustrated in FIG. 9 with the pixel size of the second ultrasonic image G2 acquired in real time illustrated in FIG. The image matching unit 154 specifies, from the coordinates (X0, Z0) to (XN, ZM), coordinates indicating the image area having the highest correlation with the ultrasonic image in the cross-sectional image M11 of the three-dimensional moving model. The image matching unit 154 calculates the position of the target 22 from the coordinates of the target 22 in the second ultrasonic image G2 by matching the specified coordinates with the coordinates of the second ultrasonic image G2.

  The target position calculation device 15 calculates the three-dimensional position of the target 22 from the position coordinates of the target 22 calculated based on the first ultrasonic image G1 and the second ultrasonic image G2, and sends the three-dimensional position to the target position output unit 17. Output.

  The three-dimensional position of the target 22 may be output in a form readable by a user from an information output device such as a display or a printer. Alternatively, the three-dimensional position of the target 22 may be output in a form usable by other devices, such as an electric signal or digital information. For example, a relative position from the reference coordinates can be displayed on a monitor by numerical values. Alternatively, three-dimensional information of the patient 2 corresponding to the simulation result of the ultrasonic cross-sectional image can be displayed on a monitor. The three-dimensional position of the target 22 may be transmitted as an encoded electric signal by wire or wirelessly. The three-dimensional position of the target 22 can be output according to the purpose of use of the three-dimensional position of the target 22. In the present embodiment, the output method of the three-dimensional position of the target 22 does not matter.

  FIG. 11 is a flowchart illustrating a process of calculating the target position. When measuring the target position, it is assumed that the patient 2 is fixed to the bed 3 and a dummy of the ultrasonic sensor 140 or the ultrasonic sensor 140 with reduced artifact is prepared.

  The three-dimensional respiration information acquisition unit 11 collects and stores three-dimensional position information for each respiration phase of the patient 2 (S11). That is, the three-dimensional respiration information acquisition unit 11 acquires and stores three-dimensional position information indicating a change in the position of the body tissue according to the respiratory state of the patient 2. Hereinafter, a case where a CT image is used as three-dimensional position information will be described as an example.

  In step S13, an ultrasonic sensor installation position is calculated. In step S13, a three-dimensional movement model is created from the stored three-dimensional respiration information. The three-dimensional movement model is generated by the three-dimensional movement model creation unit 122 using CT images at a plurality of time points including the time of inspiration 21 (1) and the time of expiration 21 (2) stored in the respiration information storage unit 121. By interpolating the movement of the tissue from the front and back volumes, a three-dimensional volume image of each respiratory phase corresponding to the timing of ultrasound imaging is provided. The three-dimensional volume image includes at least areas of the cross sections G1 and G2 to be imaged by the first and second ultrasonic sensor groups 141 and 142, and is stored in the respiration information storage unit 121 as shown in FIG. It is divided into appropriate small areas (mesh) in accordance with the three-dimensional position information due to the patient's breathing. Fat, muscle, blood vessels, bones, organs, and the like are determined from the three-dimensional position information, and a physical quantity is set for each small region according to the type of tissue. For example, it is known that the sound velocity in fat is about 1450 m / s, the sound velocity in blood, muscles and organs is about 1530 to 1630 m / s, and the sound velocity in bone is about 2700 to 4100 m / s. Set an appropriate value accordingly. Also, for example, at this time, fat, muscle, blood vessels, bones, organs, and the like can be determined according to the brightness of the CT image, and the setting can be automated by setting a physical quantity in each small area according to the type of tissue.

  The sensor installation position calculation device 13 calculates a location where the ultrasonic sensor 140 is to be installed based on the three-dimensional respiration information (S12). The position measuring device 1 instructs a user such as a laboratory technician or a doctor to install the ultrasonic sensor 140 (S14). The user attaches the ultrasonic sensor 140 to the body surface of the patient 2 at the designated position. The first ultrasonic sensor group 141 is densely arranged along a first direction which is a main movement direction of the body tissue due to respiration, and the second ultrasonic sensor group 142 is sparsely arranged in a direction orthogonal to the first direction. Be placed.

  The position measuring device 1 acquires an ultrasonic signal from the ultrasonic measuring device 14 after the ultrasonic sensor 140 is attached to a predetermined position of the patient 2. The ultrasonic measuring device 14 receives the ultrasonic reflected waves transmitted from the ultrasonic sensor groups 141 and 142, and transmits an electric signal corresponding to the received signal to the target position calculating device 15 (S15).

  The target position calculation device 15 measures the actual position of the ultrasonic sensor 140 by the sensor position measurement unit 16 in synchronization with the collection of the ultrasonic signal in step S15 (S16).

  The first ultrasonic image forming unit 151 of the target position calculating device 15 calculates the first ultrasonic image from the ultrasonic signal of the first ultrasonic sensor group 141 collected in step S15 and the position of the ultrasonic sensor 141 measured in step S16. An ultrasonic image is constructed (S17). Further, the first target position calculator 153 of the target position calculator 15 calculates the two-dimensional position of the target 22 from the first ultrasonic image created in step S17 (S18).

  On the other hand, the second ultrasonic image forming unit 152 of the target position calculating device 15 uses the second ultrasonic sensor group 142 of the three-dimensional movement model to generate an image based on the position of the second ultrasonic sensor group 142 measured in step S16. The section to be converted is extracted, and a two-dimensional section image is created (S19). The second ultrasonic image forming unit 152 obtains a second ultrasonic image from the ultrasonic signals of the second ultrasonic sensor group 142 collected in step S15 and the position of the ultrasonic sensor 142 measured in step S16. (S20).

  Then, the image comparison unit 154 of the target position calculation device 15 compares the second ultrasonic image created in step S20 with the two-dimensional cross-sectional image created based on the three-dimensional movement model (S21). The second target position calculation unit 155 of the position measurement device 1 calculates a two-dimensional position of the target 22 from the comparison result of the image comparison unit 154 (S22).

  The target three-dimensional position calculator 156 of the target position calculator 15 calculates the three-dimensional position of the target 22 from the target two-dimensional position calculated in step S18 and the target two-dimensional position calculated in step S22. (S23).

  According to the position measuring device 1 of the present embodiment configured as described above, the target position in the body of the patient 2 is accurately and rapidly performed using an ultrasonic image that is low in invasiveness and that can visualize soft tissue with high accuracy. Can be measured.

  In the present embodiment, the number of the second ultrasonic sensors 142 can be smaller than the number of the first ultrasonic sensor groups 141, so that the number of the second ultrasonic sensor groups 142 is smaller than the number of the first ultrasonic sensor groups 141. The operation time for mounting the ultrasonic sensor 140 can be shortened as compared with the case where it is made equal to:

  A second embodiment will be described with reference to FIG. In each of the following embodiments including this embodiment, the description will focus on differences from the first embodiment. In the present embodiment, a case where the position measuring device 1A is applied to a particle beam therapy system 180A as an example of a “particle beam irradiation system” will be described.

  FIG. 12 is an overall configuration diagram of the particle beam therapy system 180 including the position measuring device 1A described in the first embodiment. The position measuring device 1A according to the present embodiment is different from the position measuring device 1 in that the three-dimensional movement model creating device 12 and the target position calculating device 15A are almost integrated, The dimensional respiration information differs in that it is input to the sensor installation position calculation device 13A via the storage unit 121. However, the position measuring device 1A shown in FIG. 12 and the position measuring device 1 described in FIG. 1 have the same basic configuration.

  The particle beam therapy system 180 includes a position measuring device 1A, a particle beam irradiation unit 181, and an irradiation control unit 182. The position measurement device 1A includes a three-dimensional respiration information acquisition unit 11, a three-dimensional respiration information storage unit 121, a sensor installation position calculation device 13A, an ultrasonic measurement device 14A, and a target position calculation device 15A.

  The ultrasonic measurement device 14A further includes a waveform data holding device 144, an operation unit 145, a control unit 146, and a synchronization device 147 in addition to the ultrasonic sensor 140 and the ultrasonic transmission / reception unit 143.

  The operation unit 145 is a function for a user to operate the ultrasonic measurement device 14A. The control unit 146 has a function of controlling the ultrasonic measurement device 14A. The control unit 146 causes the ultrasonic sensor 140 to transmit ultrasonic waves in synchronization with the actual position of the ultrasonic sensor 140 based on a signal from the synchronization device 147. The waveform data holding unit 144 has a function of holding an ultrasonic waveform detected by the ultrasonic sensor 140.

  The target position calculation device 15A includes an image forming unit 150, a first target position calculation unit 153, an image comparison unit 154, a second target position calculation unit 155, a target three-dimensional position calculation unit 156, and a display image control unit. 157, an image display unit 158, and a three-dimensional movement model creation unit 122. The display image control unit 157 has a function of controlling display of the position of the target 22 and the like. The display image control unit 157 controls the image display unit 158.

  The irradiation control unit 182 has a function of controlling the operation of the particle beam therapy system 180. The irradiation control unit 182 can be configured by using a computer as described in FIG. The irradiation control unit 182 receives the target position calculated by the target position calculation device 15A from the target position output unit 17. The irradiation control unit 182 controls the irradiation position of the particle beam 1811 of the X-ray or the particle beam irradiated to the patient 2 by controlling the particle beam irradiation unit 181 based on the target position. Thereby, the particle beam therapy system 180 of the present embodiment can irradiate the particle beam in a concentrated manner on the region of the target to be treated planned in the treatment plan.

  In the particle beam therapy system 180 of the present embodiment, by monitoring the respiratory state of the patient 2, the appropriate timing at which the treatment target site passes through the target coordinate area is specified, and the irradiation of the particle beam is started or stopped. Or you can. Further, the particle beam therapy system 180 can control the irradiation of the particle beam 1811 according to the movement (displacement) of the treatment target site by calculating the target position at an appropriate frame rate.

  According to the present embodiment configured as described above, it is possible to accurately irradiate the particle beam while measuring the position of the target in the body at high speed and with high accuracy, thereby improving the reliability and usability of the particle beam therapy system. Can be done.

  A third embodiment will be described with reference to FIG. In the present embodiment, a case where the position measuring device 1B is applied to an ultrasonic treatment system 180B will be described. FIG. 13 is a diagram illustrating an overall configuration of an ultrasonic treatment system 180B including the position measuring device 1B. The position measuring device 1B has the same configuration as the position measuring device 1A.

  The ultrasonic treatment system 180B includes a position measuring device 1B, an ultrasonic irradiation unit 183, and an irradiation ultrasonic control unit 184. The irradiation ultrasonic controller 184 receives the target position calculated by the target position calculator 15A from the target position output unit 17 as a signal. The irradiation ultrasonic control unit 184 controls the ultrasonic irradiation position on the patient 2 by controlling the ultrasonic irradiation unit 183. As a result, the irradiation ultrasonic control unit 184 irradiates the ultrasonic waves with focus on the region of the treatment target site planned in the treatment plan.

  The present embodiment configured as described above has the same operation and effect as the second embodiment.

  A fourth embodiment will be described with reference to FIG. The position measuring device 1C of the present embodiment detects the respiratory phase of the patient, specifies the cross-sectional image of the three-dimensional moving model from the detected respiratory phase, and compares the cross-sectional image of the three-dimensional moving model with the second ultrasonic image. By doing so, the target position in the body is calculated.

  FIG. 14 is an overall configuration diagram of the position measuring device 1C. The position measuring device 1C detects the respiratory phase of the patient and calculates a target position in the body using the respiratory phase.

  The respiratory phase calculation unit 19 receives, from the sensor position measurement unit 16, movement information of the ultrasonic sensor 140 due to respiration. The respiratory phase calculator 19 calculates the respiratory phase of the patient 2 from the movement information according to the respiration of the ultrasonic sensor 140.

The target position calculation device 15C further includes a respiratory phase collation unit 159, as compared with the target position calculation device 15 shown in FIG.
Based on the respiratory phase calculated by the respiratory phase calculator 19, the respiratory phase collator 159 selects the position information of the body tissue of the patient 2 indicating the relevant respiratory phase from the three-dimensional movement model stored in the database 123. To create a cross-sectional image. The created cross-sectional image is collated with the second ultrasonic image by the image collation unit 154.

  The present embodiment configured as described above has the same operation and effect as the first embodiment. Further, in this embodiment, since the respiratory phase is calculated from the measurement result of the sensor position measuring unit 16, a cross-sectional image matching the respiratory phase of the patient 2 can be created from the three-dimensional movement model. Thus, the target position can be detected with higher accuracy than in the first embodiment.

  A fifth embodiment will be described with reference to FIGS. In the present embodiment, a case will be described in which the imaging section is determined from a three-dimensional volume image using the ultrasonic sensor 140D in a two-dimensional matrix in the position measuring device 1D. FIG. 15 is a diagram illustrating an overall configuration of an ultrasonic treatment system 180 including the position measuring device 1D.

  The ultrasonic measurement device 14D includes an ultrasonic sensor 140D in a two-dimensional matrix, an ultrasonic transmission / reception unit 143, and a sensor control unit 148.

  The two-dimensional matrix ultrasonic sensor 140D has sensor elements arranged in a two-dimensional matrix. The sensor control unit 148 controls the ultrasonic sensor 140D. The ultrasonic sensor 140D in the form of a two-dimensional matrix is placed on the body surface such that a target in the body moving by respiration is always present in the imaging range.

From the coordinates of the target between the acquired consecutive three-dimensional volume images, a movement path is calculated by, for example, primary interpolation. By projecting the calculated movement path onto the ultrasonic sensor surface, a sensor group (first ultrasonic sensor group) arranged in the main movement direction and a direction orthogonal to the sensor group are aligned with the target movement direction due to the patient's breathing. (Second ultrasonic sensor group) are selected from the ultrasonic sensors 140D.
FIG. 16 is a schematic diagram of a method for selecting a sensor element on the ultrasonic sensor 140D. In selecting a sensor, there is a possibility that there is a sensor element to which an ultrasonic wave transmitted toward a target does not reach due to scattering in a body tissue such as a bone. Therefore, for example, the propagation time Ti corresponding to the distance from each element to the target in the image is calculated, and if there is no signal greater than or equal to the threshold φt in the time Ti of the received signal φi of each sensor element, that element is selected. Use the selection method of not. At this time, a laboratory technician or a doctor may select a sensor element to be used by looking at a signal in the image. Thus, in the present embodiment, it is possible to calculate the position with high accuracy by excluding the sensor elements from which the ultrasonic wave does not reach the target and selecting an appropriate ultrasonic element group.
By imaging using the selected first ultrasonic sensor group and second ultrasonic sensor group, the position and size of the imaged cross section are determined and stored in the database. When calculating the target position, the position and size of the imaging section and the data condition of the sensor element are read, and each section is imaged.

The sensor control unit 148 that transmits and receives ultrasonic waves can operate only a predetermined sensor group among the first ultrasonic sensor group and the second ultrasonic sensor group. Thus, a first ultrasonic image obtained by imaging a cross section of the target in the main movement direction and a second ultrasonic image orthogonal to the main movement direction can be configured.
FIG. 17 is a flowchart showing a process for determining the position and cross section of an element group used for imaging from a three-dimensional volume image. It is assumed that the ultrasonic sensor 140D is placed on the body surface of the patient 2 so that the target position by respiration always exists within the imaging range.
The target position calculation device 15 of the present embodiment transmits ultrasonic waves from the sensor element group and acquires a reception signal in real time (S31). The target position calculation device 15 forms a three-dimensional volume image from the ultrasonic signals obtained from the positions of the sensor elements (S32). The target position calculation device 15 calculates a target position by image processing (S33). The target position calculation device 15 calculates the movement route by connecting the target positions calculated in S in chronological order and connecting them by, for example, primary interpolation (S34). Completion of the calculation of the moving route is terminated, for example, when the periodic motion due to respiration is confirmed. At this time, the sensor position of the sensor position measurement 16 may be used to check the respiratory phase. The target position calculation device 15 selects the position of the imaging section and the sensor element from the position of the target and the position of the sensor element in the acquired volume image using the above-described sensor element selection method, and the position and size of the imaging section. Is selected (S35). The target position calculation device 15 stores the result selected in S in the database (S36).

  The present embodiment configured as described above has the same operation and effect as the first embodiment. Further, in this embodiment, since the ultrasonic sensor 140D in the form of a two-dimensional matrix is used, the operation of attaching the ultrasonic sensor is easy, and furthermore, steps such as re-installation of the probe during treatment can be omitted, so that the usability is improved. And the treatment throughput is increased.

  A sixth embodiment will be described with reference to FIGS. In the present embodiment, a method of correcting an ultrasonic image from a three-dimensional movement model created by the three-dimensional movement model creation unit 12 will be described.

  As shown in FIG. 16, an ultrasonic wave is refracted in the body every time it passes through a boundary between organs having different impedances, and therefore propagates along a path as shown in FIG. FIG. 19 is time domain data of the signal D2 received by the actual ultrasonic sensors 140 (1) to 140 (4). The actual signal D2 has a difference in the propagation time t as compared with the signal D1 not considering refraction described in FIG.

  Therefore, in the present embodiment, the propagation time T0 corresponding to the positional shift corresponding to the respiration of the body tissue is added to the reception signal D1 by comparing the ultrasound image with the ultrasound image using the previously acquired three-dimensional movement model. Subtract properly. Thus, in the present embodiment, the ultrasonic image is corrected.

  FIG. 20 is a conceptual diagram showing an example of a method of calculating a displacement error from a comparison result between a three-dimensional movement model and an ultrasonic image. The operation of FIG. 20 will be described as being performed by the target position calculation device 15.

  The displacement error is calculated, for example, from a difference image G111 between the ultrasonic image G11 and the cross-sectional image G3 corresponding to the ultrasonic imaging cross-section of the three-dimensional moving model M1. That is, the displacement error is calculated from the distance ΔL between the coordinates of the peak values of the region 231 extracted as the difference between the boundaries of the organ 23 or the region 221 drawn by the difference of the target 22.

  FIG. 21 is a flowchart illustrating a process of correcting an ultrasonic image based on a three-dimensional movement model. It is assumed that the three-dimensional movement model is stored in the database 123, and an ultrasonic signal is acquired in real time from the ultrasonic sensor 140 installed on the patient 2.

  The target position calculation device 15 of the present embodiment extracts a plurality of parameters such as the shape, size, and position of the body tissue in the ultrasound image by image processing (S41). The target position calculation device 15 extracts a plurality of parameters such as the shape, size, and position of the body tissue in the three-dimensional movement model of the cross section corresponding to the ultrasonic image (S42). The target position calculation device 15 compares the parameter extracted in step S41 with the parameter extracted in step S42, and calculates the difference as an error (S43).

  The target position calculation device 15 calculates a propagation time corresponding to the error calculated in step S43 (S44). The target position calculation device 15 forms an image by adding the propagation time calculated in step S44 to the ultrasonic reception signal (S45).

  The target position calculation device 15 determines whether the error calculated in step S44 is equal to or smaller than a predetermined threshold (S46). If it is determined that the error is not less than the threshold (S46: NO), the process returns to step S43 to correct the propagation time. When determining that the error is equal to or smaller than the threshold (S46: YES), the target position calculating device 15 outputs a corrected ultrasonic image, and calculates a target three-dimensional position using the corrected ultrasonic image. (S47).

  The present embodiment configured as described above has the same operation and effect as the first embodiment. Further, in this embodiment, since the ultrasonic image can be corrected based on the three-dimensional movement model, the target position can be specified with higher accuracy, and the reliability is improved. Note that the second ultrasonic image obtained by the second ultrasonic sensor 142 can also be corrected based on the three-dimensional movement model.

  A seventh embodiment will be described with reference to FIG. In the present embodiment, a target position calculating method including a step of extracting a body tissue in an ultrasonic image and calculating a target position will be described. It is assumed that the three-dimensional movement model is stored in the database 123, and an ultrasonic signal is acquired in real time from the ultrasonic sensor 140 installed on the patient 2.

  The target position calculation device 15 extracts a plurality of parameters such as the shape, size, and position of the body tissue in the ultrasound image by image processing (S51). The target position calculating device 15 extracts a plurality of parameters such as the shape, size, and position of the body tissue in the three-dimensional movement model of the cross section corresponding to the ultrasonic image (S52).

  The target position calculation device 15 calculates the difference between the two parameters as an error by comparing the parameter extracted in step S51 with the parameter extracted in step S52 (S53). Further, the target position calculation device 15 calculates a propagation time corresponding to the calculated error (S53).

  The target position calculation device 15 determines whether the error calculated in step S43 is equal to or less than a predetermined threshold (S54). When the error is equal to or smaller than the predetermined threshold (S54: YES), the target position calculating device 15 outputs a target three-dimensional position (S55). The correlation coefficient between the ultrasonic image and the cross-sectional image obtained from the three-dimensional movement model is calculated, and when the value of the correlation coefficient exceeds a predetermined correlation coefficient threshold, the correlation coefficient is calculated from the ultrasonic image and the three-dimensional movement model. It may be determined that the obtained cross-sectional image matches.

  The present embodiment configured as described above has substantially the same operation and effect as the sixth embodiment.

  An eighth embodiment will be described with reference to FIG. FIG. 23 is a conceptual diagram of a method for calculating a position of a body tissue. In the present embodiment, an ultrasonic reflector 71 that strongly reflects ultrasonic waves is embedded in the body of the patient 2, and the position of the ultrasonic reflector 71 is calculated.

  Generally, a living tissue is a soft tissue, the attenuation of ultrasonic waves is large, and the acoustic impedance difference between the internal tissues is small, so that ultrasonic waves are hardly reflected. For this reason, a sufficient reflected signal from the in-vivo tissue (target 22) as a position calculation target may not be obtained, and a clear ultrasonic image may not be formed.

  Therefore, in this embodiment, the ultrasound reflector 71 is embedded in the patient 2 before creating the ultrasound model. The ultrasonic reflector 71 is formed such that the acoustic impedance is significantly different from that of the living tissue. In the present embodiment, a clear ultrasonic image is obtained by embedding the ultrasonic reflector 71 near the target 22 at the treatment target site in the body of the patient 2.

  If the relative coordinates between the ultrasonic reflector 71 and the body tissue (target 22) are calculated in advance at the stage of acquiring the three-dimensional respiration information, the relative coordinates can be added to the absolute coordinates of the ultrasonic reflector 71. Thereby, the position of the body tissue of interest can be calculated.

  The present embodiment configured as described above has the same operation and effect as the first embodiment.

  Note that the present invention is not limited to the embodiment described above. A person skilled in the art can make various additions and changes without departing from the scope of the present invention. The above embodiment is not limited to the configuration example illustrated in the accompanying drawings. The configuration and the processing method of the embodiment can be appropriately changed within a range that achieves the object of the present invention.

  In addition, each component of the present invention can be arbitrarily selected, and an invention having the selected configuration is also included in the present invention. Further, the configurations described in the claims can be combined other than the combinations explicitly stated in the claims.

  1, 1A, 1B, 1C, 1D: position measurement device, 11: three-dimensional respiration information acquisition unit, 12: three-dimensional movement model creation device, 13: sensor installation position calculation device, 14: ultrasonic measurement device, 15, 15A , 15B, 15C: Target position calculating device, 16: Sensor position measuring unit, 17: Target position output unit, 19: Respiratory phase calculating unit, 22: Target, 140, 140D: Ultrasonic sensor, 141: First ultrasonic sensor Group, 142: second ultrasonic sensor group, 159: respiratory phase collation unit, 180A: particle beam therapy system, 180B: ultrasound therapy system

Claims (14)

In a position measuring device that measures the position of a target in the body of a subject,
A three-dimensional movement model creating unit that creates a three-dimensional movement model indicating a three-dimensional position of the body tissue according to respiration;
A first ultrasonic sensor group arranged on a body surface along a first direction in which the target moves in the body in response to breathing;
A second ultrasonic sensor group arranged on the body surface along a second direction intersecting the first direction, wherein the second ultrasonic sensor group is arranged more sparsely than the first ultrasonic sensor group; ,
A first position calculator that calculates a first position of the target based on a position of the first ultrasonic sensor group and a first ultrasonic image obtained from a signal from the first ultrasonic sensor group;
The second position of the target is determined by comparing a second ultrasonic image obtained from a position of the second ultrasonic sensor group and a signal from the second ultrasonic sensor group with the three-dimensional movement model. A second position calculator for calculating,
A target three-dimensional position calculating unit that calculates a three-dimensional position of the target in the body from the first position and the second position;
Position measuring device comprising: The three-dimensional movement model creation unit uses the previously acquired three-dimensional position information of the in-vivo tissue during respiration of the subject to generate the three-dimensional movement model that is the three-dimensional position information of the in-vivo tissue according to the respiratory phase. create,
The position measuring device according to claim 1. The first direction is orthogonal to the second direction,
The position measuring device according to claim 1. Further, based on the position of the second ultrasonic sensor group, a respiratory phase calculating unit that calculates a respiratory phase, and based on the calculated respiratory phase, a respiratory phase included in the three-dimensional movement model. And selecting a respiratory phase to be compared with the second ultrasonic image from the, and comprises a respiratory phase matching unit to send to the second position calculation unit,
The position measuring device according to claim 2. Among a group of ultrasonic sensors in which ultrasonic sensors are arranged in a two-dimensional matrix, a plurality of ultrasonic sensors constituting the first ultrasonic sensor group and a plurality of ultrasonic waves constituting the second ultrasonic sensor group A sensor is selected,
The position measuring device according to claim 1. Furthermore, an ultrasonic image correction unit that corrects at least one of the first ultrasonic image and the second ultrasonic image based on the three-dimensional movement model,
The position measuring device according to claim 1.   A particle beam irradiation system comprising the position measuring device according to claim 1. In a position measurement method for measuring a position of a target in a subject's body,
A three-dimensional movement model creating step of creating a three-dimensional movement model indicating a three-dimensional position of the body tissue according to respiration;
A first ultrasonic wave obtained from a position of a first ultrasonic sensor group arranged on a body surface along a first direction in which the target moves in the body in response to breathing and a signal from the first ultrasonic sensor group A first position calculating step of calculating a first position of the target based on an image;
A second ultrasonic sensor group arranged on the body surface along a second direction intersecting the first direction, wherein the second ultrasonic sensor group is arranged more sparsely than the first ultrasonic sensor group; A second position calculating step of calculating a second position of the target by comparing a second ultrasonic image obtained from a position and a signal from the second ultrasonic sensor group with the three-dimensional movement model; ,
A target three-dimensional position calculating step of calculating a three-dimensional position in the body of the target from the first position and the second position;
Perform position measurement method. The three-dimensional movement model creating step uses the previously acquired three-dimensional position information of the in-vivo tissue of the subject who is breathing to extract the three-dimensional movement model that is the three-dimensional position information of the in-vivo tissue according to the respiratory phase. create,
A position measuring method according to claim 8. The first direction is orthogonal to the second direction,
A position measuring method according to claim 8. A respiratory phase calculating step of calculating a respiratory phase based on the position of the second ultrasonic sensor group; and a respiratory phase included in the three-dimensional movement model based on the calculated respiratory phase. Selecting a respiratory phase to be compared with the second ultrasound image from and sending the respiratory phase to the second position calculating step.
The position measuring method according to claim 9. Among a group of ultrasonic sensors in which ultrasonic sensors are arranged in a two-dimensional matrix, a plurality of ultrasonic sensors constituting the first ultrasonic sensor group and a plurality of ultrasonic waves constituting the second ultrasonic sensor group A sensor is selected,
A position measuring method according to claim 8. And performing an ultrasonic image correction step of correcting at least one of the first ultrasonic image and the second ultrasonic image based on the three-dimensional movement model.
A position measuring method according to claim 8. In a target position measuring method for measuring a target position in a patient with ultrasound, a step of reconstructing a plurality of three-dimensional volume images, a step of calculating a movement path of a target from the three-dimensional volume images, and The position measuring method according to claim 12, further comprising: calculating a moving direction, a position and a size of a cross section orthogonal to the moving direction, and an ultrasonic element group to be used.

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