WO2013038896A1 - Radiation dynamics imaging system and program - Google Patents

Abstract

In this radiation dynamics imaging system, in a predetermined time interval (RT1), which is determined on the basis of heartbeat information, a comparison is made with an intermittent predetermined standard irradiation pattern, and radiation is projected on an irradiation part in a specific pattern (a continuous pattern etc.), which temporally constitutes high-density irradiation. For imaging in the time interval (RT1), image information for one frame of a subject is acquired via an electrical signal generated according to the total amount of radiation received by each pixel of an imaging unit in the time interval (RT1). Thus, for locations that periodically undergo temporal changes, local brightness variations due to heartbeat phases are reduced, enabling high precision radiological images suitable for image analysis to be acquired.

Description

Radiation dynamic imaging system and program

The present invention relates to a dynamic image photographing technique for photographing a human body or an animal body using radiation.

In the medical field, various examinations and diagnoses are performed by imaging an affected part included in the internal organs or skeleton using X-rays or the like. In recent years, it has become possible to relatively easily acquire a moving image that captures the motion of an affected area using X-rays or the like by applying digital technology.

There, a semiconductor image sensor such as an FPD (flat panel detector) can be used to capture a dynamic image of a subject area including the target region. It has become possible to carry out diagnosis by analyzing the movement of a part or the like. For example, extraction of ventilation information in the lung field from chest X-ray dynamic images, and examination of supporting diagnosis / treatment (CAD for X-ray animation) by quantitative analysis of dynamic functions based on changes in lung field concentration and movement Has been.

However, in the above-mentioned chest X-ray dynamic image acquisition, when continuous imaging is performed at a timing determined irrespective of the movement of an organ or the like, a part of the X-ray image changes in brightness locally due to the influence of blood flow or noise. There is a problem that it may cause an erroneous analysis result.

For this reason, various techniques have been proposed for photographing methods for analyzing with high accuracy.

For example, Patent Documents 1 and 2 disclose a method in which the timing of heartbeats is accurately monitored, and X-ray pulses are irradiated at a timing synchronized therewith, so that imaging is performed at a timing that matches the phase of the heartbeat.

Patent Document 3 discloses a technique for performing X-ray imaging at a predetermined cycle, recording an X-ray moving image, and simultaneously recording an electrocardiogram, and analyzing the X-ray moving image according to the heartbeat property. .

Japanese Patent No. 4508405 Japanese Patent No. 4457678 International Publication No. WO2007 / 078012

In the techniques of Patent Documents 1 and 2 described above, since the imaging timing is synchronized with the heartbeat of the heart, imaging is generally performed in the same blood flow state in each heartbeat cycle, but the heartbeat cycle and phase are accurately determined. Is difficult to identify, and there is a slight difference between the imaging timing and the heartbeat phase in each heartbeat cycle. For this reason, the local blood flow state (local brightness distribution on the captured image) differs between images captured in each heartbeat cycle, and it is difficult to reduce such fluctuations.

Also in the technique of the above-mentioned Patent Document 3, since X-ray imaging is performed at a predetermined cycle such as 30 frames in 5 seconds, a captured image at a desired heartbeat phase is not always obtained. In that case, it becomes difficult to analyze an appropriate X-ray moving image in accordance with the heartbeat property.

The present invention has been made in view of such circumstances, and the radiation of the subject in a situation where the geometric state of a predetermined part of the subject changes periodically with respect to a human or animal body as the subject. An object of the present invention is to provide a radiation dynamic image capturing system capable of acquiring a dynamic image for performing an appropriate analysis in obtaining a dynamic image.

The “geometric state” as used herein refers to general geometrical elements that can be grasped by radiography, such as the shape of an organ and the stretched state of a skeleton and muscles.

The radiation dynamic image capturing system according to one aspect of the present invention is a radiation dynamic image capturing that captures a radiation image in a situation in which a geometrical state of a predetermined part of the subject changes periodically with a human body or an animal body as a subject. In the system, an irradiation unit that irradiates the subject with acupuncture radiation, an imaging unit that converts radiation irradiated from the irradiation unit and transmitted through the subject into image information, and a phase detection unit that detects phase information of the heartbeat of the subject A control unit that controls the timing of radiation irradiation in the irradiation unit and imaging in the imaging unit, and a mode setting unit that sets one of the first and second operation modes as the operation mode of the control unit In the first operation mode, the control unit irradiates the irradiation unit with radiation with an intermittent predetermined reference irradiation pattern. On the other hand, in the second operation mode, the time is higher in density than the reference irradiation pattern within a predetermined time interval determined according to the heartbeat phase based on the detection result detected by the phase detection unit. In the irradiation control unit that irradiates the irradiation unit with radiation in a specific pattern to be irradiated, and in the first operation mode, a plurality of continuous in time according to intermittent irradiation of radiation in the reference irradiation pattern An imaging control unit that causes the imaging unit to acquire image information according to high-density irradiation of radiation in the specific pattern within the time interval, while causing the imaging unit to acquire image information. And.

According to the present invention, in obtaining a radiological moving image of a subject in a situation where a geometrical state of a predetermined part of the subject changes periodically with respect to a human or animal body as a subject, the influence of a shift from the heartbeat phase is affected. Therefore, it is possible to provide a radiation dynamic image capturing system capable of acquiring a dynamic image for performing appropriate analysis.

FIG. 1 is a diagram illustrating an overall configuration of a radiation dynamic image capturing system 100 according to the first embodiment. FIG. 2 is a diagram illustrating an example of a dynamic image captured by radiological image capturing. FIG. 3 is a diagram illustrating an example of a radiation dynamic image capturing method in the first operation mode. FIG. 4 is a diagram illustrating an example of another radiodynamic image capturing method in the first operation mode. FIG. 5 is a block diagram showing a functional configuration of the radiation dynamic image capturing system 100 according to the first embodiment. FIG. 6 is a schematic diagram for explaining a radiation dynamic image capturing method in the second operation mode. FIG. 7 is a schematic view illustrating a part of a waveform measured by an electrocardiograph. FIG. 8 is a flowchart for explaining a basic operation realized in the radiation dynamic image capturing system 100 according to the first embodiment. FIG. 9 is a diagram illustrating an overall configuration of a radiation dynamic image capturing system 100 ′ according to the second embodiment. FIG. 10 is a block diagram showing a functional configuration of a dynamic radiation image capturing system 100 ′ according to the second embodiment. FIG. 11 is a diagram illustrating a setting state of coordinate axes for an image. FIG. 12 is a schematic view illustrating the variation in the lateral width of the heart. FIG. 13 is a schematic diagram for explaining the irradiation method of the radiation dynamic image capturing system 100 ′ according to the second embodiment. FIG. 14 is a block diagram showing a functional configuration of a radiation dynamic image capturing system 100 ″ according to the third embodiment. FIG. 15 is a schematic diagram for explaining the irradiation method of the radiation dynamic image capturing system 100 ″ according to the third embodiment. FIG. 16 is a block diagram showing a functional configuration of a radiation dynamic image capturing system 100A according to the fourth embodiment. FIG. 17 is a flowchart for explaining a basic operation realized in the radiation dynamic image capturing system 100A according to the fourth embodiment. FIG. 18 is a block diagram showing a functional configuration of a radiation dynamic image capturing system 100B according to the fifth embodiment. FIG. 19 is a flowchart for explaining a basic operation realized in the dynamic radiation image capturing system 100B according to the fifth embodiment.

<1. First Embodiment>
The radiation dynamic image capturing system in the first embodiment of the present invention will be described below.

<1-1. Overall Configuration of Radiation Dynamic Imaging System>
The radiation dynamic image capturing system according to the first embodiment captures a radiographic image in a situation in which the geometric state of a predetermined part of the subject periodically changes with a human or animal body as a subject.

FIG. 1 is a diagram showing an overall configuration of a radiation dynamic image capturing system according to the first embodiment. As shown in FIG. 1, the dynamic radiographic imaging system 100 includes an imaging device 1, an imaging console 2, a diagnostic console 3, and an electrocardiograph 4. The imaging device 1 and the electrocardiograph 4 are connected to the imaging console 2 via a communication cable or the like, and the imaging console 2 and the diagnostic console 3 are connected via a communication network NT such as a LAN (Local Area Network). Has been configured. Each device constituting the radiation dynamic image capturing system 100 conforms to the DICOM (Digital Image and Communication Communications in Medicine) standard, and communication between the devices is performed according to the DICOM standard.

<1-1-1. Configuration of photographing apparatus 1>
The imaging apparatus 1 is configured by, for example, an X-ray imaging apparatus or the like, and is an apparatus that captures the chest dynamics of the subject M accompanying breathing. Dynamic imaging is performed by acquiring a plurality of images sequentially in time while repeatedly irradiating the chest of the subject M with radiation such as X-rays. A series of images obtained by this continuous shooting is called a dynamic image. Each of the plurality of images constituting the dynamic image is called a frame image.

As shown in FIG. 1, the imaging device 1 includes an irradiation unit (radiation source) 11, a radiation irradiation control device 12, an imaging unit (radiation detection unit) 13, a reading control device 14, a cycle detection unit 15, The cycle detection device 16 is provided.

The irradiation unit 11 irradiates the subject M with radiation (X-rays) according to the control of the radiation irradiation control device 12. The illustrated example is a system for the human body, and the subject M corresponds to the person to be inspected. Hereinafter, the subject M is also referred to as a “subject”.

The radiation irradiation control device 12 is connected to the imaging console 2 and controls the irradiation unit 11 based on the radiation irradiation condition input from the imaging console 2 to perform radiation imaging.

The radiation irradiation conditions input from the imaging console 2 are, for example, pulse rate, pulse width, pulse interval, X-ray tube current value, X-ray tube voltage value, filter type, etc. during continuous irradiation. The pulse width is a radiation irradiation time per one radiation irradiation, and the pulse interval is a time from the start of one radiation irradiation to the next radiation irradiation start in continuous imaging.

The imaging unit 13 is configured by a semiconductor image sensor such as an FPD, and converts the radiation irradiated from the irradiation unit 11 and transmitted through the subject M into an electrical signal (image information). The FPD has, for example, a glass substrate, receives radiation irradiated from the irradiation unit 11 and transmitted through at least the subject M at a predetermined position on the substrate, and accumulates charges according to the intensity of the radiation. A plurality of unit elements that output an electrical signal corresponding to the accumulated charge amount are arranged in a matrix. Each unit element corresponds to a pixel, and is configured by a switching unit such as a TFT (Thin-Film-Transistor).

The reading control device 14 is connected to the imaging console 2. The reading control device 14 controls the switching unit of each pixel of the imaging unit 13 based on the image reading condition input from the imaging console 2 and switches the reading of the electrical signal accumulated in each pixel. Then, the image data is acquired by reading the electrical signal accumulated in the imaging unit 13. Then, the reading control device 14 outputs the acquired image data (frame image) to the photographing console 2. The image reading conditions are, for example, a frame rate, a frame interval, a pixel size, an image size (matrix size), and the like. The frame rate is the number of frame images acquired per second and matches the pulse rate. The frame interval is the time from the start of one frame image acquisition operation to the start of the next frame image acquisition operation in continuous shooting, and coincides with the pulse interval.

Here, the radiation irradiation control device 12 and the reading control device 14 are connected to each other, and exchange synchronization signals with each other to synchronize the radiation irradiation operation and the image reading operation.

The cycle detection device 16 detects the breathing cycle of the subject M and outputs the cycle information to the control unit 21 of the imaging console 2. The cycle detection device 16 also measures and controls the cycle detection sensor 15 that detects the movement of the chest of the subject M (respiration cycle of the subject M) by laser irradiation and the time of the respiratory cycle detected by the cycle detection sensor 15. A timing unit (not shown) that outputs to the unit 21.

<1-1-2. Configuration of Shooting Console 2>
The imaging console 2 outputs radiation irradiation conditions and image reading conditions to the imaging apparatus 1 to control radiation imaging and radiographic image reading operations by the imaging apparatus 1, and also captures dynamic images acquired by the imaging apparatus 1. Displayed for confirmation of whether the image is suitable for confirmation of positioning or diagnosis.

As shown in FIG. 1, the imaging console 2 includes a control unit 21, a mode setting unit 28, a storage unit 22, an operation unit 23, a display unit 24, an analysis unit 25, and a communication unit 26. Each part is connected by a bus 27.

The control unit 21 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the control unit 21 reads the system program and various processing programs stored in the storage unit 22 in accordance with the operation of the operation unit 23, expands them in the RAM, and performs shooting control processing described later according to the expanded programs. Various processes including the beginning are executed to centrally control the operation of each part of the imaging console 2 and the operation of the imaging apparatus 1 (details will be described later). The control unit 21 is connected to a timer (not shown).

The storage unit 22 is configured by a nonvolatile semiconductor memory, a hard disk, or the like. The storage unit 22 stores various programs executed by the control unit 21 and data such as parameters necessary for execution of processing by the programs or processing results.

For example, the storage unit 22 stores a shooting control processing program for executing shooting control processing described later. The storage unit 22 stores radiation irradiation conditions and image reading conditions. Various programs are stored in the form of readable program code, and the control unit 21 sequentially executes operations according to the program code.

In addition, the storage unit 22 stores a breathing cycle table. The breathing cycle table stores a range of reference time (seconds) of one breathing cycle when breathing is stable for each category of the subject M (infant, schoolchild, adult (male)...). It is. The category of the subject M is classified by subject information (age, sex).

The operation unit 23 includes a keyboard having cursor keys, numeric input keys, various function keys, and the like, and a pointing device such as a mouse, and controls instruction signals input by keyboard operations and mouse operations. To the unit 21. In addition, the operation unit 23 may include a touch panel on the display screen of the display unit 24. In this case, the operation unit 23 outputs an instruction signal input via the touch panel to the control unit 21. Furthermore, the user can give to the mode setting unit 28 via the operation unit 23 an instruction to execute one of the first and second operation modes described later.

The display unit 24 includes a monitor such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays input instructions, data, and the like from the operation unit 23 in accordance with display signal instructions input from the control unit 21. To do.

The analysis unit 25 analyzes a predetermined part based on the image information obtained from the imaging unit 13. That is, the analysis unit 25 performs image analysis on the image data output from the reading control device 14 or the image data temporarily stored in the storage unit 22. Examples of the image analysis here include extraction of a lung field region and blood flow analysis (for example, see International Publication WO2007 / 0778012). Then, the image information generated as a result of analysis by the analysis unit 25 is output to the display unit 24.

The mode setting unit 28 sets one of the first and second operation modes described later as the operation mode of the control unit 21. The mode setting unit 28 sets the operation mode of the control unit 21 to a second operation mode described later when the analysis unit 25 performs analysis. That is, when the user gives an instruction to perform image analysis to the mode setting unit 28 via the operation unit 23, the mode setting unit 28 instructs the control unit 21 to execute the second operation mode.

The communication unit 26 includes a LAN adapter, a modem, a TA (Terminal Adapter), and the like, and controls data transmission / reception with each device connected to the communication network NT.

<1-1-3. Configuration of diagnostic console 3>
The diagnosis console 3 is a device for displaying a dynamic image transmitted from the imaging console 2 and allowing a doctor to perform an interpretation diagnosis.

As shown in FIG. 1, the diagnostic console 3 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit 34, an analysis unit 35, and a communication unit 36. They are connected by a bus 37.

The control unit 31 includes a CPU, a RAM, and the like. The CPU of the control unit 31 reads the system program and various processing programs stored in the storage unit 32 in accordance with the operation of the operation unit 33, expands them in the RAM, and executes various processes according to the expanded programs. The operation of each part of the diagnostic console 3 is centrally controlled.

The storage unit 32 is configured by a nonvolatile semiconductor memory, a hard disk, or the like. The storage unit 32 stores various programs executed by the control unit 31 and data such as parameters necessary for execution of processing by the programs or processing results. These various programs are stored in the form of readable program codes, and the control unit 31 sequentially executes operations according to the program codes.

The operation unit 33 includes a keyboard having cursor keys, numeric input keys, various function keys, and the like, and a pointing device such as a mouse. The control unit 33 controls an instruction signal input by key operation or mouse operation on the keyboard. To 31. The operation unit 33 may include a touch panel on the display screen of the display unit 34, and in this case, an instruction signal input via the touch panel is output to the control unit 31. Further, the user can give an instruction to the mode setting unit 28 from the operation unit 33 to execute one of the first and second operation modes described later. That is, when the user gives an instruction to perform image analysis to the mode setting unit 28 via the operation unit 33, the mode setting unit 28 instructs the control unit 21 to execute the second operation mode.

The display unit 34 is configured by a monitor such as an LCD or a CRT, and displays an input instruction, data, or the like from the operation unit 33 in accordance with an instruction of a display signal input from the control unit 31.

The analysis unit 35 performs the same image analysis as described above on the image data output from the reading control device 14 or the image data temporarily stored in the storage unit 32. Then, the image information generated as a result of analysis by the analysis unit 35 is output to the display unit 34.

The communication unit 36 includes a LAN adapter, a modem, a TA, and the like, and controls data transmission / reception with each device connected to the communication network NT.

<1-1-4. Configuration of electrocardiograph 4>
Although the electrocardiograph 4 is shown away from the subject M in FIG. 1, each electrode terminal of the electrocardiograph 4 is actually attached to the subject M, and the heart of the subject M is shown. The radio wave form is output as a digital signal.

As shown in FIG. 1, the electrocardiograph 4 includes a phase detection unit 41, and the phase detection unit 41 performs an imaging operation by the imaging device 1 in response to a control signal from the CPU of the control unit 21. As basic information for synchronization, the phase of the heartbeat of the subject M is detected. The phase detection unit 41 can also be provided in the imaging console 2.

<1-2. First Operation Mode of Radiation Dynamic Imaging>
A first operation mode of the radiation dynamic image capturing system 100 in the first embodiment will be described.

FIG. 2 is a dynamic image captured in the first operation mode of radiodynamic image capturing with respect to the dynamics of the chest of the subject M accompanying breathing, and FIG. 3 shows the subject in the first operation mode. FIG. 3 is a diagram showing a respiratory cycle and a heart rate in M in association with imaging timings in FIG. 2. The imaging timing PT coincides with the irradiation timing for irradiating radiation, and the subject M is irradiated with radiation having a pulse width that gives the minimum dose necessary for imaging in the form of repeated pulses. .

Here, the “first operation mode” means that the irradiation unit 11 is irradiated with radiation with an intermittent predetermined reference irradiation pattern, and is continuous in time according to the intermittent irradiation of radiation with the reference irradiation pattern. This is an operation mode for causing the imaging unit 13 to acquire a plurality of pieces of image information. As an example of the imaging conditions in the first operation mode, a frame rate of 7.5 frames / second and a pulse width of 2 ms can be cited.

As shown in FIG. 2, the radiation images M1 to M10 are acquired by continuously photographing one cycle C of the respiratory cycle B of FIG. 3 at a constant photographing timing PT. Specifically, images captured at the imaging timing PT at times t = t1, t2, t3, ..., t10 correspond to the radiation images M1, M2, M3,. In the first operation mode, a smooth moving image can be displayed by continuously displaying the radiation images M1 to M10 that are continuously captured at a certain imaging timing PT.

In addition, the respiratory cycle B is composed of inspiration and expiration. The respiratory cycle consists of one exhalation and one inspiration. In inhalation, the area of the lung field in the thorax increases as the diaphragm lowers and breathes in. The maximum inspiration is when you inhale as much as you can (the conversion point between inspiration and expiration). In expiration, the area of the lung field decreases as the diaphragm rises and exhales, but the maximum exhalation occurs when exhaled to the maximum (the conversion point between exhalation and inspiration). That is, as shown in FIGS. 2 and 3, since the imaging timing TP from time t = t1 to time t = t5 belongs to the inspiratory section of the breathing cycle B of the subject M, the radiographic image M1 to the radiographic image M5. The region of the lung field expands over time until the maximum inspiration is reached at the imaging timing TP at time t = t5. On the other hand, since the imaging timing TP from time t = t6ｔ to time t = t10 に belongs to the expiration period of the breathing cycle B of the subject M, the lung field region contracts from the radiographic image M6 to the radiographic image M10. Then, the expiration becomes almost maximum at the imaging timing TP at time t = t10.

On the other hand, regarding the relationship between the respiratory cycle B and the heart rate H, the resting respiratory rate is generally about 12 to 20 times / minute, while the heart rate is about 60 to 70 times / minute. . For this reason, as shown in FIG. 3, the influence of the heart rate H in one cycle C of the respiratory cycle B, that is, the phase of the heart rate is different in each cycle even if the phase is the same in the respiratory cycle B. A local brightness change occurs in a part of the radiation images M1 to M10 due to the influence of the state fluctuation. For example, a radiological image M1 taken at time t = t1 in one cycle C and a radiographic image M10 taken at time t = t10 局 所 have the same respiratory phase but different heartbeat phases, so they are locally between them. Changes in brightness may occur. Therefore, when the analysis is performed using the output value (shading) of each pixel based on the radiation image acquired in the first operation mode, an erroneous analysis result is calculated due to the influence of the brightness change described above. There is a possibility that.

As a method for solving the above-described problem, it is conceivable that an integral image for canceling the heart rate is generated by digital addition synthesis with respect to the radiation image obtained within one period C of the respiratory cycle. FIG. 4 is a conceptual diagram for generating an integral image based on the information of the heart rate H for the radiation images M1 to M10 (see FIG. 2) obtained in one cycle C of the respiratory cycle B of FIG. That is, integration areas (time zones) I1, I2, and I3 are provided in the time axis direction for each heartbeat based on the information of the heartbeat H, and three radiation images are generated. Specifically, in the integration area I1, one integral image is generated from the radiation images M2, M3, and M4 taken at time t = t2, t3, t4, and in the integration area I2, the image is taken at time t = t5, t6. One integrated image is generated from the radiographic images M5, M6, and in the integration area I3, one integrated image is generated from the radiographic images M7, M8, M9 taken at time t = t7, t8, t9.

However, even in the method using the integral image, since the radiation irradiation is a repetitive pulse similar to that in FIG. 3, when there is no radiation image at a desired timing in the integral area corresponding to one heartbeat, Even if the integral image is generated, the local brightness change may not be completely cancelled. Specifically, in the case of FIG. 4, the integration area I1 is integrated based on the three images of the radiation images M2, M3, and M4, but in the integration area I2, the two images of the radiation images M5 and M6 are integrated. Therefore, when compared with the integrated image in the integration area I1, there is a possibility that more local brightness changes remain in the integrated image in the integration area I2. That is, even if the time widths of the integration areas I1 to I3 are the same, the number of images included in each of the integration areas I1 to I3 is different unless the time width is an integral multiple of one period of the radiation pulse. End up.

In addition, in the integral image of the integral area I1 and the integral image of the integral area I3, both are integrated based on the three radiographic images, but at the imaging timing of one heartbeat, that is, at the waveform position of the heartbeat, The time t = t2, t3, t4 in the integration area I1 and the time t = t7, t8, t9 in the integration area I3 do not completely coincide. Therefore, since the waveform position of the heartbeat H is not the three radiation images acquired under the same conditions, it cannot be said that even if the integrated image is generated, the local brightness change can be reduced to the same extent.

As described above, in the method for generating an integral image for canceling the heart rate in the first operation mode, not only the degree of reduction in local brightness change differs for each integration area, but also the timing required for diagnosis. Image information may be lost, and this is not a method for completely solving the above problem.

In order to solve the problem in the first operation mode, in the first embodiment, the second operation mode is provided, and radiation is irradiated with high density in time within a predetermined time interval determined according to the heartbeat phase. At the same time, an electrical signal corresponding to the high-density irradiation is generated to obtain image information of the subject M (generally a subject). The term “high-density irradiation in time” as used herein is a term including not only “continuous irradiation” but also “irradiation using short-period repetitive pulses” (quasi-continuous irradiation).

<1-3. Specific Configuration of Radiation Dynamic Imaging System 100>
In the radiation dynamic imaging system 100 according to the first embodiment of the present invention, in addition to the first operation mode, a predetermined time interval determined according to the heartbeat phase based on the detection result detected by the phase detector 41. The irradiation unit 11 is irradiated with radiation in a specific pattern that is high-density irradiation in time compared to the reference irradiation pattern, and image information corresponding to the high-density irradiation of radiation with the specific pattern in the time interval is captured by the imaging unit 13. And a second operation mode (hereinafter, referred to as “second operation mode”) to be acquired. That is, within a predetermined time interval determined according to the heartbeat phase, radiation is irradiated with high density in time, and an electric signal corresponding to the total amount of radiation received by each pixel of the imaging unit 13 in the time interval is generated. One image can be acquired by generating each of the unit elements constituting the pixels. Further, when there is a possibility that the output of the imaging unit 13 is saturated in the time interval, a plurality of images are acquired by dividing the time interval, and they are integrated by digital synthesis operation to obtain one image. It is also possible to obtain.

In the following, such a predetermined time interval will be referred to as a “specific time interval”, and shooting in that time interval (as an analogy with shutter release shooting with an optical camera) will be referred to as “continuous exposure shooting”. .

<1-3-1. Functional Configuration of Radiation Dynamic Imaging System 100>
FIG. 5 is a block diagram showing a functional configuration of the radiation dynamic image capturing system 100 according to the first embodiment. In the control unit 21 of the imaging console 2 in the radiation dynamic image capturing system 100, a CPU or the like operates according to various programs. It is a figure which shows the function structure implement | achieved by the control part 21 by doing with other structures.

In the first operation mode, the control unit 21 causes the irradiation control unit 120 and the imaging control unit 140 to irradiate the irradiation unit 11 with an intermittent predetermined reference irradiation pattern, and intermittently uses the reference irradiation pattern. The imaging unit 13 is made to acquire a plurality of temporally continuous image information according to radiation irradiation. On the other hand, in the second operation mode, the control unit 21 performs timing control between radiation irradiation in the irradiation unit 11 and imaging in the imaging unit 13 based on the detection result detected by the phase detection unit 41. Specifically, this timing control is realized by the time interval determination unit 110, the irradiation control unit 120, and the imaging control unit 140.

In the following, the functional configuration of the control unit 21 as shown in FIG. 5 will be described as being realized by executing a program installed in advance, but it may be realized with a dedicated hardware configuration. .

Hereinafter, the specific contents of each process performed by the time interval determination unit 110, the irradiation control unit 120, and the imaging control unit 140 in the second operation mode will be mainly described sequentially with reference to FIG.

<1-3-1-1. Time section determination unit 110>
FIG. 6 is a diagram conceptually showing the irradiation time in the second operation mode in association with heart rate information and respiration information. As shown in FIG. 6, in the second operation mode, radiation is densely irradiated (continuous irradiation) in time within a specific time interval RT determined according to the phase of the heartbeat H.

Therefore, the time interval determination unit 110 determines a specific time interval RT as shown in FIG. 6 based on the phase information of the heartbeat of the subject M. Here, the heartbeat phase information can be calculated by the following method.

<1-3-1-1-1. First heart rate information calculation method: electrocardiograph detection result>
In the first embodiment, the result obtained from the phase detection unit 41 of the electrocardiograph 4 is used as the heartbeat information calculation method (first heartbeat information calculation method). FIG. 7 is a diagram illustrating an electrocardiogram waveform of the subject M. In FIG. 7, the horizontal axis indicates time, and the vertical axis indicates the magnitude (voltage) of the electric signal, and the so-called P wave, Q wave, R wave, S wave, T wave, and U wave shapes are shown. Curves showing changes in electrical signals including curves Pp, Qp, Rp, Sp, Tp and Up are shown. Here, the PR interval is from the beginning of the P wave to the beginning of the R wave, the PR interval is from the end of the P wave to the beginning of the R wave, the QRS interval is from the beginning of the Q wave to the end of the S wave, and the end of the S wave is from The period from the beginning of the T wave to the beginning of the T wave is referred to as the ST interval, and the period from the end of the S wave to the end of the T wave is referred to as the ST interval.

Therefore, the time interval determination unit 110, based on the detection result acquired from the phase detection unit 41, the above points (Pp, Qp, Rp, Sp, Tp and Up), the interval (PR, QRS, and ST), and the interval (PR and ST) are calculated, and the start timing and end timing of the specific time interval RT are determined.

In FIG. 6, a specific time interval RT for high-density irradiation is set to a time obtained by combining three intervals of the PR interval, the QRS interval, and the ST interval in the heartbeat electrical signal shown in FIG. 7. On the other hand, as the specific time interval RT, for example, the start timing may be Pp, the end timing may be Tp, or only the QRS interval may be considered in consideration of the X-ray exposure dose. In this case, in the electrocardiogram waveform, it is preferable to set the specific time interval RT to include the specific phase with the R point as the specific phase.

Such determination of the heartbeat phase may be performed by real-time observation of the electrocardiogram waveform by the phase detector 41 or may be performed by prediction calculation based on detection of heartbeats of several past to several tens of beats. In the former, a slight delay occurs due to the signal processing in the phase detector 41, but no error due to the difference between prediction and actuality occurs. In the latter case, conversely, there is a possibility that a prediction error may occur, but since the signal delay of the electrocardiogram waveform can be compensated in consideration in advance, a delay due to this can hardly occur. In any case, there is a possibility that a slight timing shift may occur in phase identification, but in a specific time interval, continuous exposure shooting is performed while performing high-density irradiation in time, so even if such a timing shift occurs, If a heartbeat phase important for diagnosis (hereinafter referred to as “important phase”) is included in the specific time interval, it is possible to prevent the X-ray image information in the important phase from being missed.

<1-3-1-2. Irradiation Control Unit 120>
In the first operation mode, the irradiation control unit 120 in FIG. 5 causes the irradiation unit 11 to emit radiation with an intermittent predetermined reference irradiation pattern as described above. On the other hand, in the second operation mode, the irradiation control unit 120 temporally compares with the reference irradiation pattern within a specific time interval RT determined according to the heartbeat phase based on the detection result detected by the phase detection unit 41. The irradiation unit 11 is irradiated with radiation in a specific pattern that is high-density irradiation (continuous irradiation). That is, in response to the second operation mode set by the mode setting unit 28, the irradiation control unit 120 performs high-density irradiation in time within the specific time interval RT determined by the time interval determination unit 110. It inputs into the radiation irradiation control apparatus 12 so that the irradiation part 11 may be irradiated with a radiation with the specific pattern.

<1-3-1-2-1. First Irradiation Method: Continuous Irradiation>
In the second operation mode of the first embodiment, radiation is continuously emitted within a specific time interval RT (first radiation method). That is, the specific pattern of radiation irradiation is a continuous pattern in which irradiation is continued in time.

That is, as shown in FIG. 6, the specific time interval RT is irradiation by a specific pattern, and the irradiation control unit 120 sets a continuous pattern in which irradiation is continuous in time within the specific time interval RT. The length of the specific time interval RT is determined based on the heartbeat phase, and is, for example, 0.3 seconds to 1 second. In the second operation mode of the first embodiment, X-ray irradiation is not performed in the time zone before and after the specific time interval RT from the viewpoint of suppressing the exposure amount of the subject M. On the other hand, in the second operation mode, when it is desired to acquire images also in the time zone before and after the specific time interval RT, in the time zone other than the specific time interval RT, as in the first operation mode, intermittently. The irradiation unit 11 may be irradiated with radiation with a predetermined reference irradiation pattern, and the imaging unit 13 may acquire an image according to intermittent irradiation of radiation with the reference irradiation pattern.

In this second operation mode, the specific pattern of radiation irradiation within the specific time interval RT is a continuous pattern in which irradiation continues in time, so that the time change of a predetermined part (here, lungs) and the time due to the heartbeat Image information suitable for analysis can be obtained while avoiding the influence of interference with changes. Even if the start timing and end timing of the specific time interval RT1 are slightly shifted, the important phase in the heartbeat is included in the specific time interval RT, and continuous exposure shooting is performed throughout the specific time interval RT. X-ray image information is not missed.

As a result, more appropriate medical judgment can be made by image analysis. Further, since only one image is obtained in the specific time interval RT, the integration of the image information in the specific time interval RT is automatically automatically performed as a physical phenomenon, so a large number of digital images are temporarily stored. There is no need for digital integration.

<1-3-1-3. Imaging Control Unit 140>
The imaging control unit 140 causes the imaging unit 13 to acquire image information in synchronization with radiation irradiation. In particular, in the second operation mode, image information corresponding to high-density irradiation (continuous irradiation) of radiation in a specific pattern within a specific time interval RT is acquired by the imaging unit 13. That is, in the imaging control unit 140, in the imaging in the specific time interval RT determined by the irradiation control unit 120, the imaging control unit 140 is generated according to the total amount of radiation received by each pixel of the imaging unit 13 in the specific time interval RT. A command is given to the reading control device 14 so that the image information of the subject M is acquired by the electrical signal. Note that, as described above, it is also possible to acquire a plurality of pieces of image information by dividing the shooting in the time interval RT into a plurality of times, and to acquire one piece of image information by integrating them by digital synthesis. .

That is, the imaging control unit 140 performs control so as to continuously accumulate image information throughout the continuous pattern time within a specific time interval RT and acquire a radiation image for one frame (see FIG. 6).

<1-3-2. Basic Operation of Radiation Dynamic Imaging System 100>
FIG. 8 is a flowchart for explaining the basic operation realized in the radiation dynamic image capturing system 100 according to this embodiment. Since the individual functions of each unit have already been described (see FIG. 5), only the entire flow of the second operation mode will be described here.

As shown in FIG. 8, first, in step S <b> 1, the time interval determination unit 110 of the control unit 21 based on the detection result acquired from the phase detection unit 41 of the electrocardiograph 4, the heart rate information of the subject M. Is calculated (see FIG. 7).

In step S2, the time interval determination unit 110 sets a specific time interval RT based on the heart rate information of the subject M calculated in step S1 (see FIG. 6). Here, both the start timing and end timing of the specific time section RT are determined based on the detection result of the phase detector 41 (first heart rate information calculation method).

In step S3, the timing of radiation irradiation and imaging is controlled. That is, the irradiation control unit 120 controls the irradiation unit 11 via the radiation irradiation control device 12 so that irradiation is performed in a continuous pattern within the time interval RT determined in step S2.

Further, the imaging control unit 140 controls the imaging unit 13 via the reading control device 14 so as to acquire image information corresponding to the total radiation amount of the continuous pattern controlled by the irradiation control unit 120 within the specific time interval RT. (See FIG. 6).

In step S4, based on the timing of radiation irradiation and imaging controlled in step S3, the irradiation unit 11 irradiates the subject M with radiation, and the imaging unit 13 is irradiated from the irradiation unit 11 and the subject M. A charge corresponding to the amount of radiation that has passed through is accumulated for each pixel over time.

In step S5, an output command signal is given from the reading control device 14 to the image capturing unit 13, whereby each unit element (pixel) of the image capturing unit 13 stores the amount of charge accumulated up to that point (that is, the pixel). An electrical signal corresponding to the total amount of radiation received is output. Image data for one frame is acquired as a set of electrical signals from each pixel, and the acquired image data is output to the imaging console 2 (or diagnostic console 3).

In step S6, the analysis unit 25 (or the analysis unit 35) performs image analysis on the image data output in step S5. Specifically, lung field extraction, blood flow analysis, and the like are performed using the data of each pixel, and the generated image information is output to the display unit 24 (or display unit 34).

As described above, in the radiation dynamic image capturing system 100, as shown in FIG. 6, when the radiation is irradiated in a continuous pattern in the time interval RT (second operation mode), the first operation mode shown in FIG. Compared with the above, it is possible to obtain not only image information at a specific time point but also a radiation image corresponding to information obtained by continuously observing the state of the subject M over a relatively long time. For this reason, the acquisition of image information at a required specific time (important phase) is less likely to fail. In addition, since an image that is temporally averaged in this time interval RT is obtained, local brightness changes that occur only in a specific phase are less likely to appear in the radiographic image, and stable imaging with reduced such influence can be performed. It becomes possible.

For this reason, in radiographic imaging in a situation where the geometric state of a predetermined part periodically changes over time (for example, a situation where the shape of the lung changes over time due to breathing), the time of the predetermined part Appropriate image information suitable for analysis can be obtained while avoiding the influence of interference between the change and the time change due to the heartbeat. This makes it possible to make appropriate medical decisions.

In the first embodiment, the imaging unit 13 itself generates a radiation image corresponding to the total amount of radiation received for each pixel on the imaging unit 13 (that is, as a physical phenomenon on the imaging unit 13). Since integration is automatically performed by charge accumulation, etc., a series of radiation images as shown in FIG. 4 are obtained once and then compared with the case of numerical integration (accumulation or averaging). This eliminates the need to temporarily store a large number of radiation images to be integrated, and eliminates the time for integration calculation.

<2. Second Embodiment>
FIG. 9 is a diagram showing an overall configuration of a radiation dynamic image capturing system 100 ′ according to the second embodiment. In the first embodiment, the heart rate information is obtained from the phase detection unit 41 of the electrocardiograph 4, but in the second embodiment, the heart width is detected by analyzing the image of the frame image, and the detection is performed. Based on the result, the phase information of the heartbeat of the subject M is obtained. For this reason, the overall configuration of the dynamic radiographic imaging system 100 ′ shown in FIG. 9 does not include the electrocardiograph 4, and the imaging console 2 ′, the control unit 21 ′, and the analysis unit 25 ′ are the first embodiment. Is different. Other than that, it is the same structure as 1st Embodiment.

FIG. 10 is a block diagram showing a functional configuration of the radiation dynamic image capturing system 100 ′. In comparison with the functional configuration (FIG. 5) of the system 100 of the first embodiment, the analysis unit 25 ′ includes a phase detection unit 41 ′ instead of the phase detection unit 41 of the electrocardiograph 4.

<2-1. Phase detector 41 ′, time interval determiner 110 ′>
The phase detection unit 41 ′ (FIG. 10) in the analysis unit 25 ′ detects the heart width by image analysis of the frame image, and detects the phase information of the heartbeat of the subject M based on the detection result. Then, the time interval determination unit 110 ′ determines the specific time interval based on the phase information of the heartbeat of the subject M detected by the phase detection unit 41 ′.

Note that the time interval determination unit 110 'also determines the specific time interval so that the important phase is included in the specific time interval. Hereinafter, the heart rate information calculation method executed by the phase detection unit 41 'will be specifically described.

<2-1-1. Second Heart Rate Information Calculation Method: Heart Width>
In the second embodiment, the lateral width of the heart is calculated using the captured image acquired by the reading control device 14 to obtain heart rate information (second heart rate information calculation method). In other words, it is a precondition that the heart is captured together with the lung, which is the predetermined region to be imaged, in the lung motion image during breathing and the lung motion image during breath stop. Specifically, by detecting fluctuations in the lateral width of the heart in the breathing lung motion image and the breathing stop lung motion image, the heart at the timing when each breathing frame image and each breathing stop frame image was taken. The phase of the beat is detected. Accordingly, the lateral width of the heart is detected as the phase of the heart beat. Therefore, in the second embodiment, it is necessary to obtain an accuracy sufficient to calculate the lateral width of the heart even in image analysis by imaging with the reference irradiation pattern. The purpose is to perform image analysis.

FIG. 11 shows that for each breathing frame image and each breathing-stop frame image, a predetermined point (for example, the upper left point) is a reference point (for example, the origin), the right direction is the X axis direction, and the lower direction is the Y axis direction. This is an image coordinate plane drawn so that the value of coordinates changes one by one for each pixel.

FIG. 12 is a schematic view illustrating the change in the lateral width of the heart captured by the lung motion image during breathing stop. 12A to 12C illustrate a state in which the lateral width of the heart increases from w1 to w3 in the process of expanding the heart.

As a method for detecting the width of the heart from each breathing frame image and each breathing-stop frame image, for example, a method of detecting the outline of the heart can be cited. As a method for detecting the outline of the heart, various known methods can be employed. For example, using a model (heart model) indicating the shape of the heart, a feature point in the X-ray image, Detecting the outline of the heart by matching with the features of the heart model (for example, "Image feature analysis and computer-aided diagnosis in digital radiography: Automated analysis of sizes of heart and lung in chest images", Nobuyuki Nakamori et al., Medical Physics, Volume 17, Issue 3, May, 1990, pp.342-350.

Therefore, after the phase detection unit 41 ′ calculates the heart rate information by the above-described method, the time interval determination unit 110 ′ can determine, for example, the time when the lateral width of the heart starts to spread as the start timing of the specific time interval. .

In this second heart rate information calculation method, time-sequential X-ray images in the thorax are required, but X-rays at predetermined time intervals are also obtained by periodic X-ray irradiation outside the specific time interval RT1 (FIG. 13). Since images (frame images) are obtained, the heart amplitude at each time point can be specified using them, and the start timing of a specific time interval can be determined.

On the other hand, since only one X-ray image is acquired in the specific time interval RT1, the heartbeat phase is determined by acquiring the X-ray image in real time within the specific time interval RT1 and specified based on it. The end timing of the time interval RT1 cannot be determined. For this reason, the end timing of the specific time interval RT1 needs to be determined separately, and the most basic method is a method in which a time point after a predetermined time from the start timing of the specific time interval RT1 is set as the end timing. The value of the time can be predicted and calculated from the detection results of the past several to several tens of beats. Even if a slight error occurs in the prediction calculation, if the time length of the specific time interval RT1 is kept long to some extent, the image information in the important phase will not fall out of the X-ray image obtained in the specific time interval RT1. Absent.

<2-2. Irradiation control unit 120 ′>
In the first operation mode, the irradiation control unit 120 ′ causes the irradiation unit 11 to emit radiation with an intermittent predetermined reference irradiation pattern, while in the second operation mode, the irradiation control unit 120 ′ detects the radiation by the phase detection unit 41 ′. On the basis of the detected result, the irradiation unit 11 is irradiated with radiation in a specific pattern that is high-density irradiation (continuous irradiation) in time compared with the reference irradiation pattern within a predetermined specific time interval RT1 determined according to the heartbeat phase. . In other words, the irradiation control unit 120 ′ receives the second operation mode set by the mode setting unit 28, and is continuous in time within the specific time interval RT1 determined by the specific time interval determination unit 110 ′. Input is made to the radiation irradiation control device 12 so that the irradiation unit 11 is irradiated with radiation in a specific pattern to be irradiated. In the second embodiment, since a heartbeat phase is detected using an image, a periodic reference irradiation pattern having a relatively long period in the time zone before and after the specific time interval RT1 in the second operation mode. According to the above, the subject M is irradiated with radiation from the irradiation unit 11.

FIG. 13 is a graph showing the temporal change between the radiation irradiation (pulse intensity) and the lateral width of the heart in the second operation mode of the second embodiment.

As for the graph of the heart width, a plurality of frame images during breathing stop making up the lung motion images during breathing stop are used, and the relationship between the taken time and the width of the heart is illustrated, and the horizontal axis is the phase (time ), The vertical axis indicates the width of the heart, and the circle indicates the width value of the detected heart. For example, if the lateral width of the heart captured at time t is Hwt and the lateral width of the heart captured at time t + 1 is Hwt + 1, if (Hwt + 1−Hwt) ≧ 0 holds, at time t The captured respiratory frame image is classified when the heart is dilated, and if (Hwt + 1−Hwt) <0 holds, the respiratory frame image captured at time t is classified when the heart contracts. The

As shown in FIG. 13, the specific time interval RT1 corresponds to the specific time interval RT of FIG. 6, and the time when the heart is expanded corresponds to the start timing, and the time when the heart sufficiently contracts corresponds to the end timing. is doing. In addition, the specific time interval RT1 is set to irradiation with a specific pattern, and the irradiation control unit 120 'sets the irradiation pattern to be a continuous pattern in which irradiation is continued in time within the specific time interval RT1. On the other hand, in the time zone before and after specific time section RT1, it is set as the reference irradiation pattern which performs intermittent irradiation periodically. As described above, the heartbeat phase is not determined by acquiring X-ray images in real time within the specific time interval RT1. Therefore, the circles in the specific time interval RT1 in FIG. 13 are predicted and calculated from the detection results of heart beats of several past to several tens of beats. In order to perform this prediction calculation, a heartbeat detection result of several beats to several tens of beats may be obtained using the reference irradiation pattern.

Also in the second embodiment, as in the first embodiment, even if the start timing and end timing of the specific time interval RT1 are slightly shifted, the important phase in the heartbeat (for example, the phase in which the lateral width of the heart in FIG. 13 is maximized). ) Is included in the specific time interval RT1 and continuous exposure imaging is performed throughout the specific time interval RT1, so that X-ray image information in the important phase is not missed.

<2-3. Imaging Control Unit 140 ′>
In the first operation mode, the imaging control unit 140 ′ causes the imaging unit 13 to acquire a plurality of temporally continuous image information according to the intermittent irradiation of radiation with the reference irradiation pattern, while the second operation mode In the operation mode, the image capturing unit 13 is caused to acquire image information corresponding to high-density irradiation of radiation in a specific pattern within the specific time interval RT1. In the second operation mode, the imaging control unit 140 ′, in the imaging in the specific time interval RT1 determined by the irradiation control unit 120 ′, the radiation received by each pixel of the imaging unit 13 in the time interval RT1. While the image information of the subject M is acquired by the electric signal generated according to the total amount, in the time zone before and after the specific time interval RT1, the imaging unit 11 causes each unit irradiation time (1 A command is given to the reading control device 14 so as to generate a radiation image for each (pulse irradiation time). As described above, the imaging control unit 140 ′ performs imaging in synchronization with irradiation in both the first and second operation modes. Note that, as described above, it is also possible to acquire a plurality of pieces of image information by dividing the shooting in the time interval RT1 into a plurality of times, and integrate them by a digital composition operation to acquire one piece of image information. .

Then, in the specific time interval RT1, the imaging control unit 140 ′ performs control so as to continuously accumulate image information throughout the continuous pattern time so as to acquire one frame of radiation image, and before and after the specific time interval RT1. In this time zone, the imaging unit 11 is caused to generate a radiation image for each unit irradiation time (time corresponding to the pulse width) of the reference irradiation pattern (see FIG. 13).

Next, a case where a dynamic image is displayed in the second operation mode of the second embodiment will be described.

As shown in FIG. 13, the radiation image for one frame obtained in the specific time interval RT1 receives more radiation than the radiation image obtained by radiation for each pulse in the time zone before and after that. Therefore, the signal level as a whole is high. For this reason, in the case of the irradiation mode as shown in FIG. 13, for the radiation image for one frame obtained in the specific time interval RT1, the radiation irradiation time Ts (see FIG. 13) in the specific time interval RT1 and its In order to convert the signal level at the radiation irradiation time ΔTp for each pulse in the preceding and following time zones, the signal level value of each pixel is multiplied by a conversion constant (ΔTp / Ts). In other words, conversion is performed to convert the integral value obtained by charge accumulation into an average value.

Then, the radiographic images of each frame are arranged in time sequence and reconstructed as a dynamic image. At this stage, the image for one frame may be repeatedly used for a time corresponding to the specific time interval RT1. That is, since the specific time interval RT1 is longer than the time interval (pulse period) for one frame in the preceding and following time zones, when images of each frame are simply arranged, only the portion of the specific time interval RT1 is in a fast-forward state. If the diagnosing doctor knows this situation and observes the dynamic image, that may be sufficient, but if the time axis of the dynamic image is to be closer to reality, it is equivalent to one frame obtained in the specific time interval RT1. The image may be used repeatedly only by the reciprocal (Ts / ΔTp) times of the conversion constant (ΔTp / Ts). If the number of repetitions is an integer, it is most faithful to the actual time axis. For this purpose, the ratio of Ts: ΔTp is preferably an integer.

Thus, in the time zone before and after the specific time interval RT1 in the second operation mode, the imaging unit 13 generates image information for each unit irradiation time of the reference irradiation pattern, and in the specific time interval RT1. The image information for one frame is generated and used repeatedly. As a result, although not as much as in the first operation mode, it is possible to display a dynamic image that is smooth to some extent.

<3. Third Embodiment>
FIG. 14 is a block diagram showing a functional configuration of a radiation dynamic image capturing system 100 ″ according to the third embodiment. In the first and second embodiments, radiation irradiation is continuously performed in a specific time interval. However, in the third embodiment, the radiation irradiation in the specific time interval is high-density irradiation and is intermittent.Hereinafter, the third embodiment will be described focusing on the points changed from the second embodiment. In the control unit 21 ″ (FIG. 14) used in the dynamic radiation imaging system 100 ″ of the third embodiment, the irradiation control unit 120 ″ and the imaging control unit 140 ″ are different from those of the second embodiment. The remaining configuration is the same as that of the system of the second embodiment.

<3-1. Irradiation control unit 120 ">
The irradiation control unit 120 ″ performs both the first and second operation modes similarly to the irradiation control unit 120 ′, but the irradiation method in the second operation mode differs from the irradiation control unit 120 ′ in the following points. That is, the irradiation controller 120 ′ in the second embodiment performs continuous irradiation, whereas the irradiation controller 120 ″ in the third embodiment performs high-density irradiation and intermittent irradiation.

<3-1-1. Second irradiation method: High-density irradiation (change of pulse interval)>
In the third embodiment, a repetitive pulse train that gives a higher dose of radiation than the reference irradiation pattern is used as a specific pattern of radiation irradiation within a specific time interval in the second operation mode (second irradiation). Method).

FIG. 15 is a graph showing the temporal change between the radiation irradiation (pulse intensity) and the lateral width of the heart in the second operation mode of the third embodiment.

As shown in FIG. 15, the specific time interval RT2 corresponds to the specific time interval RT1 in FIG. 13, when the heart is expanded corresponding to the start timing, and when the heart is sufficiently contracted corresponds to the end position. is doing. Further, the specific time section RT2 is irradiated with a specific pattern. Here, the reference irradiation pattern in the time zone before and after the specific time section RT2 is a repetitive pulse train having a relatively long cycle, like the reference irradiation pattern in the first operation mode, whereas the specific pattern is the reference pattern. It consists of a repetitive pulse train having a relatively short period so as to give a higher radiation dose than the irradiation pattern.

More specifically, the reference irradiation pattern is a first periodic pulse train in which pulses having a predetermined pulse width PW are periodically arranged at the first pulse interval PS. On the other hand, in the specific pattern, the pulse width PW2 has the same pulse width as the predetermined pulse width PW, but has a second period having a second pulse interval PS2 shorter than the first pulse interval PS. Pulse train. In other words, in the specific time interval RT2, a pulse train having a duty ratio larger than that in the preceding and following time zones is used. As an example of the first and second periodic pulse trains, the first periodic train pulse is 7.5 pulses / second, the second periodic train pulse is 30 pulses / second, and the pulse width is 2 ms in any case. .

In the second irradiation method described above, the specific pattern is a repetitive pulse train that gives a higher dose of radiation in terms of time than the reference irradiation pattern, so that a quasi-continuous multi-pulse is generated in the time interval RT2. Irradiation is possible. As a result, it is possible to obtain appropriate image information suitable for analysis while avoiding the influence of interference between the time change of the predetermined part and the time change due to the heartbeat, so that appropriate medical judgment can be made.

Unlike the first irradiation method, in the second irradiation method, the X-ray irradiation in the specific time interval RT2 is not complete continuous irradiation. Therefore, when the start timing and end timing of the specific time section RT2 are slightly shifted, the X-ray image information at the important phase in the heartbeat is not completely captured. However, if the pulse interval in the specific time section RT2 is set short, X-ray image information very close to the important phase can always be captured. The image information can be captured at the important phase at a practically sufficient level.

Further, only one image is obtained even in the specific time interval RT2, and the integration of the image information in the specific time interval RT2 is substantially automatically performed as a physical phenomenon. Similarly to the first irradiation method, it is not necessary to store and perform digital integration calculation.

<3-2. Imaging control unit 140 ">
The imaging control unit 140 ″ has the same function as the imaging control unit 140 ′ and performs imaging in synchronization with irradiation in both the first and second operation modes.

In other words, the imaging control unit 140 ″ performs control so as to continuously accumulate image information throughout the time of the second periodic pulse train and acquire a radiographic image for one frame within the specific time interval RT2 (FIG. On the other hand, in the time zone before and after the specific time section RT2, the imaging unit 11 is caused to generate a radiation image for each unit irradiation time (time corresponding to the pulse width) of the reference irradiation pattern.

Note that the radiation image for one frame obtained in the specific time interval RT2 receives more radiation than the radiation image obtained by radiation for each pulse in the time zone before and after that, so the signal level is high. Overall it is getting higher. For this reason, when performing radiation irradiation in specific time section RT2 like FIG. 15, the above-mentioned conversion constant is equivalent to the number of pulses contained in specific time section RT2, and becomes an integer of 2 or more.

As described above, in the radiation dynamic imaging system 100 ″, as shown in FIG. 15, by irradiating the radiation within the specific time interval RT2 with the second periodic pulse train, not only the image information at a specific time point, A radiation image corresponding to information obtained by continuously observing the state of the subject M over a relatively long time can be obtained.

In the present embodiment, the second periodic pulse train is used as the irradiation method in the specific time interval RT2, but it is also possible to apply this irradiation method to the radiation dynamic imaging system 100 according to the first embodiment. It is. That is, the irradiation method in the time interval RT of FIG. 6 can be used by replacing the continuous pattern with the second periodic pulse train.

<4. Fourth Embodiment>
FIG. 16 is a block diagram showing a functional configuration of a radiation dynamic image capturing system 100A according to the fourth embodiment. The control unit 21A (FIG. 16) used in the radiation dynamic image capturing system 100A is used as an alternative to the control unit 21 (FIG. 5) in the system 100 of the first embodiment. The difference from the first embodiment is that the irradiation control unit 120A includes an irradiation pattern switching unit 130. The remaining configuration is the same as that of the system of the first embodiment.

The irradiation pattern switching unit 130 selects the irradiation pattern in the specific time interval RT as the first irradiation method (continuous pattern) or the second irradiation method (second) based on the result of estimating the total exposure dose of the subject M. Switch to an appropriate method. In this case, when the total exposure dose does not exceed the predetermined determination threshold, the first irradiation method is adopted, and when the total exposure dose exceeds the predetermined determination threshold, the second irradiation method is adopted. Switch to This is because the second irradiation method (second periodic pulse train) requires less total exposure than the first irradiation method (continuous pattern).

<4-1. Basic Operation of Radiation Dynamic Imaging System 100A>
Subsequently, FIG. 17 is a diagram illustrating an operation flow of the radiation dynamic image capturing system 100A according to the fourth embodiment. Here, based on the predicted value of the total exposure dose, the irradiation pattern in the time interval RT is switched to either the first irradiation method or the second irradiation method. In FIG. 17, steps ST1, ST2, ST7 to ST10 are the same as steps S1 to S6 in FIG.

In the fourth embodiment, the following steps are added by adding the irradiation pattern switching unit 130 that did not exist in the first embodiment.

That is, as shown in FIG. 17, in step ST3, the irradiation pattern switching unit 130 estimates the total exposure dose of the subject M due to radiation irradiation.

By the way, since the total exposure dose is proportional to the cumulative exposure time of radiation, if the temporal pattern of radiation exposure is specified, the exposure dose in dynamic imaging for one heartbeat can be easily understood. Therefore, when a configuration is set in which how many heartbeats are to be taken as a whole during dynamic imaging, the total exposure can be predicted and calculated before the start of dynamic imaging. In addition, if you have a configuration in which laboratory technicians or doctors arbitrarily instruct the completion of dynamic imaging without setting in advance how many heartbeats to perform dynamic imaging, Based on the exposure dose, it is possible to predict how many heart rates will continue to be captured after that until the total exposure dose reaches the determination threshold. In the latter case, when the heart rate until the determination threshold is reached is less than or equal to a predetermined number, the irradiation pattern after that point may be switched to a reference irradiation pattern with a lower exposure dose. it can.

On the other hand, the flow of FIG. 17 assumes the former case, and step ST3 is executed before the dynamic imaging is started, and the heart rate scheduled to continue the dynamic imaging and one heart rate in each irradiation pattern. The total exposure dose of the subject M is estimated and calculated using the information on the exposure dose at.

In step ST4, the irradiation pattern switching unit 130 determines whether or not the total exposure amount estimated in step ST3 exceeds a predetermined threshold value. That is, if the estimated total exposure is within the determination threshold, the process proceeds to step ST5, and the irradiation pattern in the time interval RT is set as the first irradiation method (continuous pattern). Going forward, the irradiation pattern in the specific time interval RT is set as the second irradiation method (second periodic pulse train).

Then, as a process similar to that of the first embodiment, the operation flow is completed through steps ST7 to ST10.

As described above, in the radiation dynamic image capturing system 100A, the total exposure amount of the subject due to radiation irradiation is estimated, and when the total exposure amount exceeds a predetermined determination threshold, the irradiation pattern in the specific time interval is switched. Thus, it is possible to prevent a useless exposure dose received by the subject.

In the above description, when the total exposure dose exceeds the predetermined determination threshold, the irradiation pattern in the specific time section is switched to the second irradiation method (second periodic pulse train). It is also possible to change so as to switch to a pattern.

In the case of this modification, the irradiation pattern switching unit 130 switches the irradiation pattern to the reference irradiation pattern when the total exposure amount of the subject M due to radiation irradiation in the second operation mode exceeds a predetermined determination threshold value. Thereby, when the total exposure amount exceeds a predetermined determination threshold value, even in the specific time interval RT, the total exposure amount is set to a predetermined value by forcibly switching the irradiation pattern from the specific pattern to the reference irradiation pattern. Can be prevented. Note that when switching to the reference irradiation pattern, an image for one frame may be generated for each irradiation pulse in the specific time interval as in the first operation mode.

<5. Fifth Embodiment>
FIG. 18 is a block diagram showing a functional configuration of a radiation dynamic image capturing system 100B according to the fifth embodiment. The control unit 21B (FIG. 18) used in the radiation dynamic image capturing system 100B is used as an alternative to the control unit 21 (FIG. 5) in the system 100 of the first embodiment. The difference from the first embodiment is that the time section determination unit 110B includes an error processing unit 115. The remaining configuration is the same as that of the system 100 of the first embodiment.

The error processing unit 115 estimates the future phase of the heartbeat of the subject M based on the phase detection result of the heartbeat detected by the phase detection unit 41, thereby starting and ending timing of the specific time interval RT in the future. When the difference between the phase estimated for each time point and the actual heartbeat phase detected by the phase detector 41 is equal to or greater than a predetermined determination threshold, Stop radiation.

<5-1. Basic Operation of Radiation Dynamic Imaging System 100B>
Subsequently, FIG. 19 is a diagram illustrating an operation flow of the radiation dynamic image capturing system 100B according to the fifth embodiment. Among these, steps SP1, SP3 to SP7 are the same as steps S1 to S6 in FIG.

In the fifth embodiment, it is assumed that the past heart rate detection results detected in the past by the first heart rate information calculation method are stored in the storage unit 22 of the imaging console 2B before the start. By adding the error processing unit 115 that did not exist in the embodiment, the following steps are added.

That is, as shown in FIG. 19, in step SP2, the error processing unit 115 estimates the future phase of the heartbeat of the subject M based on the detection result stored in the storage unit 22, The start timing and end timing of the specific time interval RT in the future are set, and the difference between the phase estimated for each time point and the actual heartbeat phase detected by the phase detection unit 41 exceeds a predetermined threshold value It is determined whether or not. If the difference between the estimated heartbeat phase and the actual phase is within the determination threshold, the process proceeds to step SP3, and if it is greater than or equal to the determination threshold, the error processing unit 115 forcibly ends the operation flow. By doing so, irradiation of the subject M with radiation is stopped.

That is, the specific time interval RT is set in advance as a time interval including a desired heartbeat phase. However, when the heartbeat phase is shifted due to, for example, a sudden arrhythmia, the predetermined time interval RT is set to the desired heartbeat phase. The phase may not be included. Even if the desired heartbeat phase falls within the specific time interval RT, if the specific time interval RT deviates significantly from the phase interval assumed in advance, an expected radiographic image cannot be obtained, and dynamic imaging is performed again. There may also be situations where you have to. Then, if the dynamic imaging is continued even when the phase shift occurs, the subject M is subjected to unnecessary exposure for obtaining an image that is not actually used for diagnosis.

Therefore, as in the fifth embodiment, when the phase shift becomes large, the dynamic imaging is stopped in the middle, and the dynamic imaging is started again, thereby preventing the excessive exposure received by the subject M. It becomes possible.

<6. Modification>
As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

* In the above description, the radiation dynamic imaging system 100, 100 ′, 100 ″, 100A, 100B is described separately for each embodiment so that these individual functions are not contradictory to each other. , May be combined with each other.

* In the radiation dynamic imaging system 100 ', 100 ", the second operation mode is executed when an instruction is given to perform image analysis, and the first operation mode is displayed when displaying a moving image without image analysis. Is executed.

* The part where the geometric state periodically changes over time may be not only the lung but also other organs that perform involuntary movements such as peristalsis, and parts that perform voluntary movements such as muscles and joints. It may be. In the latter case, dynamic imaging is performed while the subject is repeatedly performing the same operation.

* The subject may be an animal body as well as a human body.

DESCRIPTION OF SYMBOLS 1 Imaging device 2, 2 ', 21 ", 21A, 21B Imaging console 3 Diagnosis console 4 Electrocardiograph 11 Irradiation part 12 Radiation irradiation control apparatus 13 Imaging part 14 Reading control apparatus 21, 21', 21", 21A, 21B Control unit 25, 25 ′, 35 Analysis unit 28 Mode setting unit 41 Phase detection unit 100, 100 ′, 100 ″, 100A, 100B Radiation dynamic imaging system 110, 110 ′, 110B Time interval determination unit 115 Error processing unit 120 , 120 ', 120 ", 120A Irradiation control unit 130 Irradiation pattern switching unit 140, 140', 140" Imaging control unit RT, RT1, RT2 Specific time interval PW, PW2 Pulse width PS First pulse interval PS2 Second pulse Interval M Subject (subject)

Claims (9)

In a radiation dynamic image capturing system for capturing a radiation image in a situation where the geometric state of a predetermined part of the subject is periodically changed with a human or animal body as a subject,
An irradiation unit for irradiating the subject with radiation;
An imaging unit that converts radiation emitted from the irradiation unit and transmitted through the subject into image information;
A phase detection unit for detecting heartbeat phase information of the subject;
A control unit that performs timing control of radiation irradiation in the irradiation unit and imaging in the imaging unit;
A mode setting unit for setting one of the first and second operation modes as the operation mode of the control unit;
With
The controller is
In the first operation mode, the irradiation unit is irradiated with radiation with an intermittent predetermined reference irradiation pattern, while in the second operation mode, based on the detection result detected by the phase detection unit, An irradiation control unit that irradiates the irradiation unit with radiation in a specific pattern that is high-density irradiation in time compared to the reference irradiation pattern within a predetermined time interval determined according to a heartbeat phase;
In the first operation mode, the imaging unit acquires a plurality of temporally continuous image information in response to intermittent irradiation with the reference irradiation pattern, while in the second operation mode. An imaging control unit that causes the imaging unit to acquire image information according to high-density irradiation of radiation in the specific pattern within the time interval;
A radiation dynamic imaging system characterized by comprising: The radiation dynamic imaging system according to claim 1,
An analysis unit that analyzes the predetermined part based on image information obtained from the imaging unit;
The mode setting unit sets the operation mode of the control unit to the second operation mode when performing the analysis by the analysis unit. The radiation dynamic imaging system according to claim 1 or 2,
The radiological dynamic imaging system according to claim 1, wherein the specific pattern is a continuous pattern in which irradiation is continued in time within the time interval. The radiation dynamic imaging system according to claim 1 or 2,
The reference irradiation pattern is a repetitive pulse train,
The radiation pattern imaging system according to claim 1, wherein the specific pattern is a repetitive pulse train that gives a higher radiation dose than the reference irradiation pattern. The radiation dynamic imaging system according to claim 4,
The reference irradiation pattern is a first periodic pulse train in which pulses having a predetermined pulse width are periodically arranged at a first pulse interval.
The specific pattern is a second periodic pulse train having a second pulse interval shorter than the first pulse interval while having the same pulse width as the predetermined pulse width. Image shooting system. A radiation dynamic imaging system according to any one of claims 1 to 5,
The irradiation control unit irradiates the subject with radiation from the irradiation unit according to the reference irradiation pattern in a time zone before and after the time interval in the second operation mode,
The imaging control unit causes the imaging unit to generate image information for each unit irradiation time of the reference irradiation pattern in a time zone before and after the time interval in the second operation mode. Radiation dynamic imaging system. The radiation dynamic imaging system according to claim 6,
A radiation dynamic image, wherein the operation mode of the control unit is switched to the first operation mode when the total exposure amount of the subject due to radiation irradiation in the second operation mode exceeds a predetermined determination threshold value. Shooting system. A radiation dynamic imaging system according to any one of claims 1 to 7,
The controller is
By estimating the future phase of the heartbeat of the subject based on the detection result detected by the phase detector, the start timing and end timing of the time interval in the future are set,
When the difference between the estimated phase and the actual heartbeat phase detected by the phase detection unit is equal to or greater than a predetermined determination threshold, radiation irradiation to the subject is stopped. Radiation dynamic imaging system. A program for causing the computer to function as a control unit in the radiation dynamic imaging system according to any one of claims 1 to 8, when executed by a computer included in the radiation dynamic imaging system.

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