Intraoral imaging system

Abstract

This intraoral imaging system comprises an imaging unit and a control unit. The imaging unit executes monitor detection, and executes imaging detection a plurality of times. The control unit executes first processing, for acquiring a plurality of imaging signals, by controlling the imaging unit so as to execute imaging detection a plurality of times. The control unit determines the timing of the start and end of the imaging detection on the basis of a first monitor signal, in a case of controlling the imaging unit so as to execute the imaging detection for the first time in the first processing, and determines the timing of at least one of the start and end of the imaging detection on the basis of at least one of the imaging time information and a second monitor signal when controlling the imaging unit so as to execute the imaging detection for each of the second and subsequent times in the first processing.

Description

Intraoral imaging system

[0001] The present disclosure relates to an intraoral imaging system.

[0002] An intraoral imaging system is known that includes a radiation source that emits radiation, an imaging unit that is disposed in the oral cavity and detects the radiation that has passed through an object, and a control unit that is electrically connected to both the imaging unit and the radiation source and controls both the imaging unit and the radiation source. In such an intraoral imaging system, in order to acquire a plurality of two-dimensional images, the control unit may determine the radiation detection interval in the imaging unit based on the radiation emission interval in the radiation source (see, for example, Patent Document 1).

[0003] Patent No. 7382042

[0004] In the intraoral imaging system as described above, for example, due to changes in imaging conditions such as the characteristics of the radiation source and the state of the object, the dose of radiation incident on the imaging unit may change. In such a case, in order to accurately acquire a plurality of two-dimensional images in the intraoral imaging system as described above, not only the radiation detection interval in the imaging unit but also the radiation emission interval in the radiation source need to be adjusted, and there is a risk that the construction of the system becomes complicated.

[0005] An object of the present disclosure is to provide an intraoral imaging system that can accurately acquire a plurality of two-dimensional images while suppressing the complication of system construction.

[0006] An intraoral imaging system in one aspect of the present disclosure comprises: (1) an imaging unit that detects radiation transmitted through an object while positioned in the oral cavity; and a control unit that is electrically connected to the imaging unit and controls the imaging unit, wherein the imaging unit performs monitoring detection to acquire a monitoring signal relating to the dose of the radiation, and performs imaging detection multiple times to acquire a plurality of imaging signals relating to an image of the object; the control unit performs a first process of acquiring the plurality of imaging signals by controlling the imaging unit to perform the imaging detection multiple times; a second process of generating a plurality of two-dimensional images based on the plurality of imaging signals; and a third process of generating a three-dimensional image based on the plurality of two-dimensional images; and the control unit performs the first process... The intraoral imaging system is configured such that, when the imaging unit is controlled to perform the imaging detection on the first attempt, the start and end timings of the imaging detection are determined based on a first monitor signal obtained as the monitor signal by controlling the imaging unit to perform the monitor detection on the first attempt, and in the first process, when the imaging unit is controlled to perform the imaging detection on each subsequent attempt, the start and end timings of at least one of the imaging time information obtained when the imaging detection was performed on the first attempt, and a second monitor signal obtained as the monitor signal by controlling the imaging unit to perform the monitor detection on subsequent attempts, are determined.

[0007] In the above intraoral imaging system, when the control unit controls the imaging unit to perform imaging detection for the first time in the first process, it determines the start and end timings of imaging detection based on a first monitor signal obtained as a monitor signal by controlling the imaging unit to perform monitor detection for the first time. This allows the control unit to appropriately determine the start and end timings of imaging detection according to the imaging conditions in the first imaging detection without controlling a radiation-emitting device (e.g., a radiation source), and to acquire a two-dimensional image with high accuracy in the first imaging detection. Furthermore, when the control unit controls the imaging unit to perform imaging detection for each subsequent imaging detection in the first process, it determines the start and end timings of imaging detection based on at least one of the imaging time information obtained when imaging detection was performed for the first time and the second monitor signal obtained as a monitor signal by controlling the imaging unit to perform monitor detection for subsequent imaging detections. This allows the control unit to acquire a two-dimensional image with high accuracy in each subsequent imaging detection without controlling a radiation-emitting device. As a result, the control unit can acquire multiple two-dimensional images with high accuracy without controlling a radiation-emitting device. Therefore, the above intraoral imaging system can accurately acquire multiple two-dimensional images while suppressing the complexity of system construction.

[0008] An intraoral imaging system in one aspect of the present disclosure may be [2] "the intraoral imaging system according to [1] above, wherein the imaging unit includes imaging pixels used for imaging detection, performs imaging background detection to acquire an imaging background signal relating to the background of the imaging pixels, the control unit controls the imaging unit in the first process to perform imaging background detection at least once during a period when imaging detection is not being performed, and generates the plurality of two-dimensional images in the second process based on the imaging background signal and the plurality of imaging signals." According to this intraoral imaging system, a plurality of two-dimensional images in which the influence of the background of the imaging pixels is suppressed can be acquired with high accuracy.

[0009] An intraoral imaging system in one aspect of the present disclosure may be [3] "the intraoral imaging system described in [1] above, wherein the imaging unit includes imaging pixels used for imaging detection, performs imaging background detection multiple times to acquire a plurality of imaging background signals relating to the background of the imaging pixels, the control unit controls the imaging unit in the first process to perform imaging background detection multiple times in association with each imaging detection during periods when imaging detection is not being performed, and generates a plurality of two-dimensional images in the second process based on the plurality of imaging background signals and the plurality of imaging signals." With this intraoral imaging system, a plurality of two-dimensional images can be acquired with greater accuracy in which the influence of the background of the imaging pixels in each imaging detection after the first time is suppressed.

[0010] An intraoral imaging system in one aspect of the present disclosure may be [4] "an intraoral imaging system according to any one of [1] to [3] above, wherein the imaging unit includes a monitor pixel used for the monitor detection, performs monitor background detection to acquire a monitor background signal relating to the background of the monitor pixel, and in the first process, when the imaging unit is controlled to perform the imaging detection for the first time, the imaging unit is controlled to perform the monitor background detection for the first time before the monitor detection for the first time, and in the first process, the timing of the start of the first imaging detection is determined according to the timing when the value obtained by subtracting the intensity of the monitor background signal acquired by controlling the imaging unit to perform the monitor background detection for the first time from the intensity of the first monitor signal reaches a first threshold." With this intraoral imaging system, the control unit can suppress the influence of the background of the monitor pixel when determining the timing of the start of the first imaging detection based on the first monitor signal. As a result, when the control unit controls the imaging unit to perform the imaging detection for the first time, the imaging detection can be more reliably started during the period when radiation is being emitted.

[0011] An intraoral imaging system in one aspect of the present disclosure may be [5] "the intraoral imaging system described in [4] above, wherein the control unit controls the imaging unit to perform the imaging detection for each subsequent second time in the first process, and controls the imaging unit to perform the monitor detection for each subsequent second time, controls the imaging unit to perform the monitor background detection for each subsequent second time before performing the monitor detection for each subsequent second time, and in the first process, determines the timing of the start of each subsequent imaging detection according to the timing when the value obtained by subtracting the intensity of the monitor background signal obtained by controlling the imaging unit to perform the monitor background detection for each subsequent second time from the intensity of the second monitor signal reaches the first threshold." With this intraoral imaging system, when the control unit determines the timing of the start of each subsequent imaging detection based on the second monitor signal, the influence of the background of the monitor pixels corresponding to each subsequent imaging detection can be suppressed. As a result, when the control unit controls the imaging unit to perform the imaging detection for each subsequent second time, the imaging detection can be started more reliably during the period when radiation is being emitted.

[0012] An intraoral imaging system in one aspect of the present disclosure may be [6] "an intraoral imaging system according to any one of [1] to [5] above, wherein the control unit controls the imaging unit to perform the monitor detection once in the first process, and determines the timing of the end of the first imaging detection according to the timing when the accumulated value of the first monitor signal acquired after the timing of the start of the first imaging detection reaches a second threshold." According to this intraoral imaging system, the first imaging detection can be terminated at an appropriate timing according to the imaging conditions of the first imaging detection.

[0013] An intraoral imaging system in one aspect of the present disclosure may be [7] "an intraoral imaging system according to any one of [1] to [6] above, wherein the control unit controls the imaging unit to perform the imaging detection for each subsequent second time in the first process, and controls the imaging unit to perform the monitor detection for each subsequent second time, thereby determining the timing of the end of each subsequent imaging detection in accordance with the timing at which the accumulated value of the second monitor signal acquired after the start timing of each subsequent imaging detection reaches the second threshold." According to this intraoral imaging system, each subsequent imaging detection can be terminated at an appropriate timing according to the imaging conditions of each subsequent imaging detection.

[0014] An intraoral imaging system in one aspect of this disclosure may be the intraoral imaging system described in [6] or [7] above, wherein the first threshold is smaller than the second threshold. According to this intraoral imaging system, imaging detection can be started at an earlier timing depending on the timing of radiation emission. This reduces the amount of radiation exposure to the target object.

[0015] An intraoral imaging system in one aspect of the present disclosure may be [9] "an intraoral imaging system according to any one of [1] to [8] above, wherein the control unit controls the imaging unit to perform the imaging detection in the first process to perform the imaging detection in each subsequent imaging detection, and determines the timing of the end of the imaging detection based on the imaging time information." According to this intraoral imaging system, for example, the timing of the end of each subsequent imaging detection is determined based on the elapsed time from the start to the end of the imaging detection when the imaging detection is performed for the first time. This allows the control unit to appropriately determine the timing of the end of each subsequent imaging detection, taking into account the imaging conditions in the first imaging detection, without controlling the radiation emission configuration. As a result, the control unit can easily and accurately acquire a two-dimensional image in each subsequent imaging detection.

[0016] An intraoral imaging system in one aspect of the present disclosure may be

[10] "an intraoral imaging system according to any one of [1] to [8] above, wherein the control unit controls the imaging unit to perform the imaging detection in the first process, and determines the start and end timings of the imaging detection based on the second monitor signal." According to this intraoral imaging system, the start and end timings of each imaging detection from the second onward are determined by considering the imaging conditions in each imaging detection from the second onward. This allows the control unit to appropriately determine the start and end timings of each imaging detection from the second onward, taking into account the imaging conditions in each imaging detection from the second onward, such as the angle of incidence of radiation to the object and the intensity of radiation incident on the imaging unit, without controlling the radiation emission configuration. As a result, compared to the case where the control unit determines the end timing of the imaging detection based on imaging time information, a two-dimensional image can be acquired with even greater accuracy in each imaging detection from the second onward.

[0017] An intraoral imaging system in one aspect of the present disclosure may be

[11] "an intraoral imaging system according to any one of [1] to [8] above, wherein the control unit, in the first process, controls the imaging unit to perform the imaging detection for each subsequent imaging detection, determines the timing of the start of the imaging detection based on the second monitor signal, and determines the timing of the end of the imaging detection based on the imaging time information." With this intraoral imaging system, the control unit can more reliably start each subsequent imaging detection during the period in which radiation is emitted, without controlling the radiation-emitting configuration. Furthermore, the control unit can appropriately determine the timing of the end of each subsequent imaging detection, taking into account the imaging conditions in the first imaging detection, without controlling the radiation-emitting configuration. As a result, the control unit can acquire two-dimensional images with high accuracy in each subsequent imaging detection.

[0018] An intraoral imaging system in one aspect of the present disclosure may be

[12] "an intraoral imaging system according to any one of [1] to [8] above, wherein the control unit controls the imaging unit to perform the imaging detection on each of the nth (where n is an integer of 2 or more) imaging detections from the second time onward in the first processing, and determines the start and end timings of the imaging detection based on the second monitor signal, and controls the imaging unit to perform the imaging detection on each of the (n+1)th and subsequent imaging detections, and determines the end timing of the imaging detection based on the imaging time information." With this intraoral imaging system, the control unit can acquire two-dimensional images with even greater accuracy compared to the case where the control unit determines the end timing of the imaging detection based on the imaging time information for each of the nth (from the second time onward) imaging detections. Furthermore, the control unit can easily and accurately acquire two-dimensional images for each of the (n+1)th and subsequent imaging detections. As a result, the control unit can acquire two-dimensional images with greater accuracy for each of the second and subsequent imaging detections.

[0019] An intraoral imaging system in one aspect of the present disclosure may be

[13] "an intraoral imaging system according to any one of the above

[12] , wherein the control unit controls the imaging unit to perform monitoring detection on each subsequent imaging detection in the first process, and controls the imaging unit to perform monitoring detection on each subsequent imaging detection in the (n+1)th and subsequent imaging detections, and when the difference between the exposure time information calculated based on the second monitor signal obtained by controlling the imaging unit to perform monitoring detection on each subsequent imaging detection reaches a third threshold, the control unit determines the timing of the start and end of the imaging detection based on the second monitor signal." According to this intraoral imaging system, the control unit determines the timing of the start and end of the imaging detection based on the second monitor signal when there is a significant change in the imaging conditions in each subsequent imaging detection, for example, when there is a significant change in the intensity of radiation incident on the imaging unit. As a result, the control unit can reliably and accurately acquire a two-dimensional image even when there is a significant change in the imaging conditions in each subsequent imaging detection.

[0020] An intraoral imaging system in one aspect of the present disclosure may be

[14] "an intraoral imaging system according to any one of [1] to

[13] above, further comprising a housing that houses the imaging unit, and the control unit including a control device disposed outside the housing." According to this intraoral imaging system, when the control unit includes a control device disposed outside the housing, it is possible to acquire multiple two-dimensional images with high accuracy while suppressing the complexity of the system construction.

[0021] An intraoral imaging system in one aspect of the present disclosure may be

[15] "an intraoral imaging system according to any one of [1] to

[14] above, further comprising a housing that houses the imaging unit, and the control unit including a control circuit disposed within the housing." According to this intraoral imaging system, when the control unit includes a control circuit disposed within the housing, multiple two-dimensional images can be acquired with high accuracy while suppressing the complexity of the system construction.

[0022] According to this disclosure, it is possible to provide an intraoral imaging system that can accurately acquire multiple two-dimensional images while suppressing the complexity of system construction.

[0023] This is a diagram illustrating the configuration of an imaging system equipped with an example intraoral imaging system and a radiation source. This is a cross-sectional view of the imaging device shown in Figure 1. This is a block diagram of the imaging device and control device shown in Figure 1. This is a time chart showing an example of a first process performed in the intraoral imaging system. This is a flowchart showing an example of a first process performed in the intraoral imaging system. This is a flowchart showing an example of a first process performed in the intraoral imaging system. This is a flowchart showing an example of a first process performed in the intraoral imaging system. This is a flowchart showing an example of a first process performed in the intraoral imaging system. This is a time chart showing a first modified example of the first process performed in the intraoral imaging system. This is a flowchart showing a first modified example of the first process performed in the intraoral imaging system. This is a circuit diagram of pixels included in the image sensor shown in Figure 3. This is a time chart showing a second modified example of the first process performed in the intraoral imaging system. This is a flowchart showing a second modified example of the first process performed in the intraoral imaging system. This is a time chart showing a third modified example of the first process performed in the intraoral imaging system. This is a flowchart showing a third modified example of the first process performed in an intraoral imaging system.

[0024] An example of this disclosure will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted. [Configuration of the Intraoral Imaging System]

[0025] As shown in Figure 1, the imaging system S comprises an intraoral imaging system 100 and a radiation source 200. The intraoral imaging system 100 is a system that acquires an image (radiotransmission image) of an object T, such as a tooth, by detecting radiation R (e.g., X-rays) emitted from the radiation source 200 and transmitted through the object T. The intraoral imaging system 100 comprises an imaging device 1 and a control device 10. The imaging device 1 detects radiation R transmitted through the object T while positioned in the oral cavity. The imaging device 1 is electrically connected to the control device 10 via a cable 9. The imaging device 1 and the control device 10 transmit and receive signals (i.e., communicate) via the cable 9. The control device 10 is composed of a computer device such as a PC or tablet terminal. In the intraoral imaging system 100, when radiation R transmitted through the object T is detected by the imaging device 1, the resulting electrical signal is transmitted from the imaging device 1 to the control device 10, and an image of the object T is generated by the control device 10 based on the electrical signal.

[0026] The radiation source 200 emits radiation R towards the object T. The radiation source 200 is configured so that the angle of incidence of radiation R towards the object T can be changed. More specifically, the radiation source 200 is located outside the patient's oral cavity, while the imaging device 1 and the object T are located inside the patient's oral cavity. The radiation source 200 continuously emits radiation R of a constant intensity towards the object T. The radiation source 200 moves along a predetermined trajectory C (for example, an arc-shaped path centered on the object T) on the side of the object T opposite to the imaging device 1, while being able to emit radiation R towards the object T. For example, the radiation source 200 stops at a predetermined position for a predetermined time.

[0027] As described above, the multiple two-dimensional images acquired by the imaging device 1 are multiple two-dimensional images of the object T taken from various angles, depending on the angle of incidence of radiation R on the object T. This makes it possible to generate a three-dimensional image of the object T based on the multiple two-dimensional images. For example, in the intraoral imaging system 100, a three-dimensional image of the object is generated by the tomosynthesis method. In this case, the multiple two-dimensional images are multiple tomographic images of the object.

[0028] As shown in Figure 2, the imaging device 1 includes a wiring board 2, an image sensor 3, an FOP (Fiber Optical Plate) 4, a scintillator 5, a control circuit 6, a communication module 7, a housing 8, and a cable 9. The image sensor 3 is mounted on one main surface of the wiring board 2. The image sensor 3 is a solid-state image sensor, such as a COMS image sensor. The FOP 4 is placed on the image sensor 3. The scintillator 5 is placed on the FOP 4. The imaging device 1 receives power from a control device 10 (see Figure 1), for example, via the cable 9.

[0029] The control circuit 6 and the communication module 7 are mounted on the other main surface of the wiring board 2. The control circuit 6 is composed of an integrated circuit such as an FPGA (field-programmable gate), ASIC (Application Specific Integrated Circuit), CPLD (Complex Programmable Logic Device), or CPU (Central Processing Unit). The control circuit 6 performs various controls on the imaging device 1. The communication module 7 communicates with the control device 10 according to the instructions of the control circuit 6. The communication module 7 receives various data transmitted from the control device 10. The communication module 7 is an integrated circuit such as a USB (Universal Serial Bus) controller. As an example, the communication module 7 is a USB controller and communicates with the control device 10 in accordance with the USB standard.

[0030] The housing 8 contains the wiring board 2, image sensor 3, FOP 4, scintillator 5, control circuit 6, and communication module 7. Therefore, the control circuit 6 is located inside the housing 8, and the control device 10 is located outside the housing 8. Of the walls of the housing 8, the wall 8a along the scintillator 5 is the wall where radiation R is expected to be incident. The end of a cable 9 that penetrates the wall of the housing 8 on the opposite side of wall 8a is electrically connected to the wiring board 2. For example, the cable 9 is a USB cable.

[0031] As shown in Figure 3, the control device 10 includes a storage unit 11, a communication unit 12, a processing unit 13, an input receiving unit 14, and a display unit 15. The storage unit 11 is, for example, a hard disk, and stores various types of data. The communication unit 12 is, for example, a communication device. The processing unit 13 is, for example, a processor. The processing unit 13 executes software (programs) loaded into the memory (not shown) of the control device 10, and controls the reading and writing of data in the memory, as well as communication by the communication unit 12. The input receiving unit 14 is an interface unit that receives input of various types of data from the user. The input receiving unit 14 is, for example, a keyboard, mouse, etc. The display unit 15 displays various types of information according to instructions from the processing unit 13. The display unit 15 is, for example, a display device of the control device 10. The display unit 15 may also function as an interface unit that receives input of various types of data from the user, for example, by configuring a GUI (Graphical User Interface).

[0032] In the intraoral imaging system 100, the imaging unit 20 is composed of an image sensor 3, an FOP 4, and a scintillator 5. Therefore, the imaging unit 20 is housed in a housing 8. The imaging unit 20 detects radiation R that has passed through the target object T while positioned in the oral cavity. In the intraoral imaging system 100, the control unit 30 is composed of a control circuit 6, a communication module 7, and a control device 10. The control unit 30 communicates with the imaging unit 20 and controls the imaging unit 20. The imaging unit 20 is electrically connected to the control unit 30 by wiring (not shown) within the housing 8. The imaging unit 20 and the control unit 30 transmit and receive signals (i.e., communicate) via this wiring. The control unit 30 is electrically connected to the radiation source 200.

[0033] In the imaging device 1 configured as described above, when the housing 8 is placed inside the oral cavity, radiation R that has passed through the object passes through the wall portion 8a of the housing 8 and enters the scintillator 5 of the control unit 30, fluorescence corresponding to the intensity of the incident radiation R is emitted in the scintillator 5. When this fluorescence is guided by the FOP 4 and enters the image sensor 3, an electrical signal corresponding to the intensity of the incident fluorescence is generated in the image sensor 3, and this electrical signal is transmitted to the control circuit 6 of the control unit 30 via the wiring inside the housing 8.

[0034] The image sensor 3 of the imaging unit 20 has a plurality of imaging pixels 3A and a plurality of monitor pixels 3B. The plurality of imaging pixels 3A are arranged in two dimensions and constitute a light detection area. The plurality of imaging pixels 3A operate in a global shutter manner in which signals are read out simultaneously from each imaging pixel 3A. The plurality of monitor pixels 3B are arranged, for example, along the outer periphery of the plurality of imaging pixels 3A. The plurality of monitor pixels 3B operate in a global shutter manner in which signals are read out simultaneously from each monitor pixel 3B. Note that the number of monitor pixels 3B only needs to be at least one.

[0035] The imaging unit 20 uses a plurality of imaging pixels 3A to perform imaging detection in order to acquire an imaging signal relating to the image of the object T. The imaging unit 20 outputs the imaging signal to the control unit 30. More specifically, when the control circuit 6 controls the image sensor 3 to perform imaging detection, each imaging pixel 3A converts the fluorescence emitted by the scintillator 5 due to the incidence of radiation R into an electric charge and outputs the electric charge as an imaging signal to the control circuit 6. For example, the ASIC (Application Specific Integrated Circuit) of the image sensor 3 switches the ON / OFF of switch SW1, so that the electric charge generated in each imaging pixel 3A is output as an imaging signal. Switch SW1 is a switch of the image sensor 3 and is connected to the imaging pixels 3A and the control circuit 6. Switch SW1 is composed of, for example, a transistor.

[0036] The imaging unit 20 performs imaging background detection to acquire an imaging background signal related to the background of the imaging pixels 3A. The imaging unit 20 outputs the imaging background signal to the control unit 30. The "background of the imaging pixels 3A" refers to the charge output from the imaging pixels 3A regardless of whether or not radiation R is emitted, for example, the charge output from the imaging pixels 3A even when no radiation R is emitted. More specifically, when the control circuit 6 controls the image sensor 3 to perform imaging background detection during periods when no radiation R is emitted, each imaging pixel 3A outputs a charge to the control circuit 6 as an imaging background signal. The scintillator 5 converts radiation R into fluorescence once, and then emits weak fluorescence (phosphorescence or afterglow) over a long period regardless of whether or not radiation R is emitted. Therefore, the charge output from each imaging pixel 3A regardless of whether or not radiation R is emitted (the background of the imaging pixels 3A) may include the charge generated in each imaging pixel 3A by the weak fluorescence emitted from the scintillator 5.

[0037] The imaging unit 20 uses a plurality of monitor pixels 3B to perform monitoring detection in order to acquire a monitoring signal related to the dose of radiation R, and outputs the monitoring signal to the control unit 30. More specifically, the control unit 30 controls the imaging unit 20 so as to periodically acquire the monitoring signal in each monitoring detection. For example, when the control circuit 6 controls the image sensor 3 to perform monitoring detection, each monitor pixel 3B converts the fluorescence emitted by the scintillator 5 due to the incidence of radiation R into an electric charge, and outputs the electric charge as a monitoring signal to the control circuit 6. As an example, the ASIC of the image sensor 3 switches the ON / OFF of switch SW2, so that the electric charge generated in each monitor pixel 3B is output as a monitoring signal. Switch SW2 is a switch of the image sensor 3 and is connected to the monitor pixels 3B and the control circuit 6. Switch SW2 is composed of, for example, a transistor. In the example shown in Figure 3, the imaging pixel 3A and the monitor pixels 3B share an output line to the control circuit 6. In this case, the ASIC of the image sensor 3 can output an imaging signal from the imaging pixel 3A to the control circuit 6 by turning switch SW1 ON and switch SW2 OFF. On the other hand, the ASIC of the image sensor 3 can output a monitor signal from the monitor pixel 3B to the control circuit 6 by turning switch SW1 OFF and switch SW2 ON.

[0038] The imaging unit 20 performs monitor background detection to acquire a monitor background signal related to the background of the monitor pixels 3B. The imaging unit 20 outputs the monitor background signal to the control unit 30. The "background of the monitor pixels 3B" is the charge output from the imaging pixels 3A regardless of whether or not radiation R is emitted, for example, the charge output from the monitor pixels 3B even when radiation R is not emitted. More specifically, when the control circuit 6 controls the image sensor 3 to start monitor background detection during a period when radiation R is not emitted, each monitor pixel 3B outputs a charge as a monitor background signal. Note that the charge output from each monitor pixel 3B regardless of whether or not radiation R is emitted (the background of the monitor pixels 3B) may include the charge generated in each monitor pixel 3B by the weak fluorescence emitted from the scintillator 5.

[0039] The control unit 30 performs a first process of acquiring multiple imaging signals by controlling the imaging unit 20 to perform imaging detection multiple times, a second process of generating multiple two-dimensional images based on the multiple imaging signals, and a third process of generating a three-dimensional image based on the multiple two-dimensional images. The third process is implemented by known methods such as the tomosynthesis method described above.

[0040] In the first process, when the control unit 30 controls the imaging unit 20 to perform imaging detection for the first time, it determines the start and end timings of imaging detection based on the monitor signal (first monitor signal) obtained by controlling the imaging unit 20 to perform monitor detection for the first time.

[0041] More specifically, first, in the first process, the control unit 30 controls the imaging unit 20 to perform monitor detection for the first time. Next, in the first process, the control unit 30 determines the timing to start imaging detection according to the timing when the intensity of the monitor signal acquired by controlling the imaging unit 20 to perform monitor detection for the first time reaches a first threshold. For example, in the first process, the control unit 30 controls the imaging unit 20 to perform monitor background detection before performing monitor detection. The control unit 30 determines the timing to start imaging detection according to the timing when the value obtained by subtracting the intensity of the monitor background signal acquired by controlling the imaging unit 20 to perform monitor background detection from the intensity of the monitor signal acquired by controlling the imaging unit 20 to perform monitor detection reaches a first threshold. "Intensity of the monitor signal" refers to the intensity of each monitor signal when the imaging unit 20 is controlled to periodically output a monitor signal in each monitor detection. Also, "intensity of the monitor signal" refers to the intensity of the monitor signal at a predetermined timing when the imaging unit 20 is controlled to continuously output a monitor signal in each monitor detection. The first threshold is set in advance.

[0042] Next, in the first process, the control unit 30 controls the imaging unit 20 to perform monitor detection once, and determines the timing of the end of the first imaging detection according to the timing when the integrated value of the monitor signals acquired after the start of the first imaging detection reaches the second threshold. For example, in the first process, the control unit 30 controls the imaging unit 20 to perform monitor detection once, and determines the timing of the end of imaging detection according to the timing when the integrated value obtained by subtracting the intensity of the monitor background signal acquired by controlling the imaging unit 20 to perform monitor background detection from the intensity of the monitor signal acquired by controlling the imaging unit 20 to perform monitor background detection reaches the second threshold. The "integrated value of the monitor signal" is the sum of the intensities of multiple monitor signals when the imaging unit 20 is controlled to periodically output monitor signals in each monitoring detection. Also, the "integrated value of the monitor signal" is the sum of the intensities of the monitor signals at each predetermined timing when the imaging unit 20 is controlled to continuously output monitor signals in each monitoring detection. The first threshold described above is smaller than the second threshold. The second threshold is set in advance.

[0043] In the first process, if the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent imaging detection, it determines the timing of the end of imaging detection based on imaging time information. Imaging time information is information indicating the elapsed time from the start timing to the end timing of imaging detection when the imaging unit 20 is controlled to perform imaging detection on the first detection. For example, in the first process, if the control unit 30 controls the imaging unit 20 to perform imaging detection on the first detection, it acquires imaging time information. The control unit 30 determines the timing of the end of imaging detection based on a second predetermined time (described later) based on the imaging time information. Note that the second predetermined time was a time based on the elapsed time indicated by the imaging time information, but it may also be the elapsed time indicated by the imaging time information itself.

[0044] In the first process, the control unit 30 controls the imaging unit 20 to perform at least one imaging background detection during a period when imaging detection is not being executed. In the second process, the control unit 30 generates a plurality of two-dimensional images based on the imaging background signal and the plurality of imaging signals. For example, in the first process, when the control unit 30 controls the imaging unit 20 to perform the first imaging detection, the control unit 30 controls the imaging unit 20 to perform imaging background detection before performing the imaging detection. In the second process, the control unit 30 generates each of the plurality of two-dimensional images based on the value obtained by subtracting the intensity of the imaging background signal from the intensity of each of the plurality of imaging signals.

[0045] When the control unit 30 does not control the imaging unit 20 to perform imaging detection and imaging background detection, the control unit 30 controls the imaging pixel 3A to continuously discard the accumulated charges. When the control unit 30 does not control the imaging unit 20 to perform monitor detection and monitor background detection, the control unit 30 controls the monitor pixel 3B to continuously discard the accumulated charges. [First Process in Intraoral Imaging System]

[0046] The first process implemented in the intraoral imaging system 100 will be described with reference to FIG. 4. As shown in FIG. 4, first, the control device 10 transmits a first monitor detection start instruction C1 to the control circuit 6, and the control circuit 6 controls the imaging unit 20 to perform the first monitor detection. As a result, the monitor signal S1 is periodically acquired in the first monitor detection. Here, when the emission of the radiation R from the radiation source 200 is started, the control device 10 transmits a first imaging detection start instruction C2 to the control circuit 6 according to the timing when the intensity of the monitor signal S1 exceeds the first threshold value V1. Subsequently, the control circuit 6 controls the imaging unit 20 to start the first imaging detection, and the accumulation period T1 is started. Subsequently, according to the timing when the integrated value S2 of the monitor signal S1 acquired after the timing of the start of the first imaging detection reaches the second threshold value V2, the control device 10 transmits an instruction C3 including an instruction to end the first monitor detection and an instruction to end the first imaging detection to the control circuit 6.

[0047] Subsequently, the control device 10 transmits an instruction C4 to start reading the imaging signal to the control circuit 6. Subsequently, the control circuit 6 starts the first reading period T2. At this time, the incident angle of the radiation R with respect to the object T is changed. Subsequently, the control device 10 transmits an instruction C5 to start the second and subsequent imaging detections to the control circuit 6 at a timing when the first predetermined time has elapsed from the timing of the end of the first imaging detection. The first predetermined time is longer than the reading period T2 and longer than the time required to change the incident angle of the radiation R with respect to the object T.

[0048] Subsequently, the control circuit 6 starts the second imaging detection and starts the second accumulation period T1. Subsequently, the control circuit 6 ends the second accumulation period T1 and ends the second imaging detection. At this time, the control circuit 6 controls the timing of the end of the second imaging detection so that the length of the second accumulation period T1 is the same as the length of the first accumulation period T1. Subsequently, the control circuit 6 controls the imaging unit 20 to start reading the imaging signal. At this time, the incident angle of the radiation R with respect to the object T is changed. Subsequently, the control circuit 6 controls the imaging unit 20 to start the third imaging detection at a timing when the first predetermined time has elapsed from the timing of the end of the second imaging detection. The third and subsequent imaging detections are executed in the same manner as the second imaging detection.

[0049] In the first process, the control circuit 6 controls the imaging unit 20 to execute at least one imaging background detection during a period when the imaging detection is not being executed. For example, in the first process, the control circuit 6 controls the imaging unit 20 to execute at least one imaging background detection during a period T3 when the radiation R is not being emitted. As an example, in the first process, the control circuit 6 controls the imaging unit 20 to execute at least one imaging background detection before the timing of the start of the emission of the radiation R.

[0050] The monitor detection in the first process will be explained with reference to Figure 5. The control unit 30 performs monitor detection in the first process. For example, the control unit 30 performs monitor detection in the first process and periodically outputs a monitor signal S1. As an example, the ASIC of the image sensor 3 controls the monitor pixel 3B to periodically read the monitor signal S1 with the switch SW2 always set to ON, thereby periodically outputting the monitor signal S1 to the control circuit 6. The control unit 30 controls the imaging unit 20 to perform monitor detection while power and an operating clock are supplied to the image sensor 3 of the imaging unit 20. That is, the control unit 30 controls the imaging unit 20 to perform monitor detection on the first time.

[0051] When the control unit 30 instructs the imaging unit 20 to start accumulating charge in the monitor pixel 3B, the imaging unit 20 executes the processes in steps S01 to S05. First, the imaging unit 20 controls the monitor pixel 3B to accumulate charge (step S01). Next, the imaging unit 20 controls the monitor pixel 3B to output the accumulated charge as a monitor signal S1 to the control unit 30 (step S02). For example, in the processes of steps S01 and S02, the imaging unit 20 changes the switch SW1 to OFF and the switch SW2 to ON, thereby executing the output of the monitor signal S1.

[0052] Next, the imaging unit 20 determines whether or not the imaging pixel 3A has started outputting an imaging signal (step S03). If the imaging unit 20 determines that the imaging pixel 3A has started outputting an imaging signal (step S03: Yes), the imaging unit 20 controls the monitor pixel 3B to stop outputting the monitor signal S1 (step S04). For example, in the process of step S04, the imaging unit 20 changes the switch SW1 to ON and the switch SW2 to OFF, thereby stopping the output of the monitor signal S1.

[0053] Next, the imaging unit 20 determines whether or not the imaging pixel 3A has finished outputting the imaging signal (step S05). If the imaging unit 20 determines that the imaging pixel 3A has not finished outputting the imaging signal (step S05: No), the monitoring pixel 3B is controlled to stop outputting the monitoring signal S1 (step S04). For example, in the process of step S04, the imaging unit 20 maintains the state in which switch SW1 is ON and switch SW2 is OFF, so that the output of the monitoring signal S1 continues to be stopped.

[0054] If the imaging unit 20 determines that the imaging pixel 3A has not started outputting an imaging signal (step S03: No), or if it determines that the imaging pixel 3A has stopped outputting an imaging signal (step S05: Yes), the monitoring pixel 3B is controlled to accumulate charge (step S01). For example, the imaging unit 20 changes the switch SW1 to OFF and the switch SW2 to ON, thereby restarting the output of the monitoring signal S1.

[0055] The monitoring background detection in the first process will be explained with reference to Figure 6. First, the control device 10 sends a command to the control circuit 6 to start monitoring background detection (step S100). Subsequently, the control circuit 6 starts monitoring background detection (step S101). Next, the control device 10 sends a signal to the control circuit 6 requesting the transmission of a monitoring background signal (for example, a bulk-in request in USB communication) (step S102).

[0056] Next, the monitor pixel 3B outputs the monitor signal S1 as a monitor background signal to the control circuit 6 (step S103 (step S02 in Figure 5)). More specifically, as described above, the monitor pixel 3B periodically outputs the monitor signal S1 to the control circuit 6. The control circuit 6 acquires the monitor signal S1 received from the control device 10 after the timing of receiving a signal requesting the transmission of the monitor background signal (from step S102 onwards) as the monitor background signal.

[0057] Next, the control circuit 6 determines whether or not a monitor background signal has been received (step S104). If the control circuit 6 determines that no monitor background signal has been received (step S104: No), it determines again whether or not a monitor background signal has been received (step S104). If the control circuit 6 determines that a monitor background signal has been received (step S104: Yes), the monitor background signal is transmitted to the control device 10 (step S105). Next, the control device 10 determines whether or not a monitor background signal has been received (step S106). If the control device 10 determines that a monitor background signal has been received (step S106: Yes), it determines whether or not a predetermined number of background signals have been received (step S107). If the control device 10 determines that no monitor background signal has been received (step S106: No), or determines that a predetermined number of background signals have not been received (step S107: No), a signal requesting the transmission of a monitor background signal is transmitted again (step S102). If it is determined that a predetermined number of background signals have been received (step S107: Yes), one monitor background signal is acquired based on that predetermined number of background signals, and monitor background detection is terminated (step S108). For example, in step S108, the control device 10 acquires the result of calculating statistical values ​​(e.g., mean or median) of the predetermined number of monitor background signals as a monitor background signal.

[0058] Next, the first image detection in the first process will be explained with reference to Figures 7, 8, and 9. When the imaging unit 20 is controlled by the control circuit 6 to perform image detection for the first time, the start and end timings of the image detection are determined based on the monitor signal S1. First, refer to Figure 7. The control device 10 sends a signal to the control circuit 6 requesting the transmission of the monitor signal S1 (for example, a bulk-in request in USB communication) (step S109). Subsequently, the control circuit 6 acquires the monitor signal S1 from the monitor pixel 3B (step S110 (step S02 in Figure 5)). Subsequently, the control circuit 6 determines whether or not the monitor signal S1 has been received (step S111). Subsequently, if the control circuit 6 determines that the monitor signal S1 has not been received (step S111: No), it determines again whether or not the monitor signal S1 has been received (step S111). If the control circuit 6 determines that the monitor signal S1 has been received (step S111: Yes), the monitor signal S1 is transmitted to the control device 10 (step S112). The processes in steps S111 and S112 are repeatedly executed by the control circuit 6 from the moment a signal requesting the transmission of the monitor signal S1 is transmitted from the control device 10 (step S109) until the moment a command to end monitor detection is transmitted from the control device 10 (step S125, described later).

[0059] Next, the control device 10 determines whether or not the monitor signal S1 has been received (step S113). If the control device 10 determines that the monitor signal S1 has been received (step S113: Yes), it determines whether or not the emission of radiation R has started (step S114). For example, in the process of step S114, the control device 10 determines the timing of the start of imaging detection according to the timing when the intensity of the received monitor signal S1 reaches a first threshold V1. As an example, the control unit 30 determines the timing of the start of imaging detection according to the timing when the value obtained by subtracting the intensity of the monitor background signal from the intensity of the monitor signal S1 reaches the first threshold V1.

[0060] If the control device 10 determines that the monitor signal S1 has not been received (step S113: No), or if it determines that the emission of radiation R has not started (step S114: No), a signal requesting the transmission of the monitor signal S1 is sent again to the control circuit 6 (step S109). If the control device 10 determines that the emission of radiation R has started (step S114: Yes), an instruction to start imaging detection is sent to the control circuit 6, as shown in Figure 8 (step S115). Subsequently, the control circuit 6 controls the imaging pixel 3A to start imaging detection (step S116). The imaging unit 20 controls the imaging pixel 3A to start accumulating charge (step S117). For example, in the process of step S117, the imaging unit 20 changes the switch SW1 to OFF and the switch SW2 to ON, thereby starting the accumulation of charge in the imaging pixel 3A.

[0061] Next, as shown in Figure 8, the control device 10 sends a signal to the control circuit 6 requesting the transmission of the monitor signal S1 (step S118). Subsequently, the control circuit 6 controls the monitor pixel 3B to output the monitor signal S1 (step S119 (step S02 in Figure 4)). Next, the control circuit 6 determines whether or not the monitor signal S1 has been received (step S120). If the control circuit 6 determines that the monitor signal S1 has not been received (step S120: No), it determines again whether or not the monitor signal S1 has been received (step S120). If the control circuit 6 determines that the monitor signal S1 has been received (step S120: Yes), the monitor signal S1 is sent to the control device 10 (step S121). Subsequently, the control device 10 determines whether or not the monitor signal S1 has been received (step S122).

[0062] Next, if the control device 10 determines that the monitor signal S1 has been received (step S122: Yes), the integrated value of the monitor signal S1 is calculated (step S123). Subsequently, the control device 10 determines whether or not to terminate the imaging detection (step S124). For example, in the process of step S123, the control unit 30 calculates the integrated value of the monitor signal S1 by subtracting the intensity of the monitor background signal from the intensity of the monitor signal S1 acquired since the start of the first imaging detection, and summing the values ​​obtained from these subtractions. In the process of step S124, the control unit 30 determines whether or not the integrated value of the monitor signal S1 has reached the second threshold V2.

[0063] Next, if the control device 10 determines that the monitor signal S1 has not been received (step S122: No), or if the control device 10 determines that it will not terminate the imaging detection (step S124: No), an instruction to start imaging detection is sent to the control circuit 6 again (step S118).

[0064] As shown in Figure 9, when the control device 10 determines that imaging detection should be terminated (step S124: Yes), a monitor detection termination instruction is sent to the control circuit 6 (step S125), and the control circuit 6 outputs an instruction to the monitor pixel 3B to terminate the execution of monitor detection (step S126). For example, in the process of step S126, the imaging unit 20 stops the periodic output of the monitor signal S1 by the monitor pixel 3B. Subsequently, the control device 10 sends an imaging detection termination instruction to the control circuit 6 (step S127), and the control circuit 6 outputs an instruction to the imaging pixel 3A to terminate the execution of imaging detection (step S128). Here, the monitor detection termination instruction and the imaging detection termination instruction correspond to instruction C3 shown in Figure 4.

[0065] Next, the imaging unit 20 controls the imaging pixel 3A to terminate charge accumulation (step S129). Subsequently, the imaging unit 20 controls the imaging pixel 3A to output an imaging signal to the control circuit 6 (step S130). For example, in steps S129 and S130, the imaging unit 20 changes the switch SW1 to ON and the switch SW2 to OFF, so that the charge is output from the imaging pixel 3A as an imaging signal. Subsequently, the control circuit 6 transfers the imaging signal to the control device 10 (step S131). In step S128, the control circuit 6 stores imaging time information indicating the elapsed time from the start timing to the end timing of imaging detection.

[0066] Next, the control device 10 determines whether or not an imaging signal has been received (step S132). If the control device 10 determines that no imaging signal has been received (step S132: No), it determines again whether or not an imaging signal has been received (step S132). If the control device 10 determines that an imaging signal has been received (step S132: Yes), the first imaging detection is completed.

[0067] As described above, in the processing of steps S100 to S132, the control unit 30 determines the start and end timings of the imaging detection based on the monitor signal S1 acquired by controlling the imaging unit to perform monitor detection for the first time, when the imaging unit 20 is controlled to perform imaging detection for the first time in the first processing. For example, in the processing of steps S100 to S117, the control unit 30 determines the start timing of the first imaging detection when the value obtained by subtracting the intensity of the monitor background signal acquired by controlling the imaging unit 20 to perform monitor background detection for the first time from the intensity of the monitor signal S1 acquired by controlling the imaging unit 20 to perform monitor detection for the first time reaches a first threshold V1. In the processing of steps S118 to S124, the control unit 30 determines the end timing of the imaging detection when the integrated value S2 obtained by subtracting the intensity of the monitor background signal from the intensity of the monitor signal S1 acquired after the start timing of the first imaging detection reaches a second threshold V2.

[0068] Next, the second and subsequent imaging detections in the first process will be explained with reference to Figure 10. When the imaging unit 20 is controlled by the control circuit 6 to perform imaging detection each time from the second time onward, the timing of the end of imaging detection is determined based on the imaging time information. First, after the process in step S132 is executed, the control circuit 6 determines whether or not a first predetermined time has elapsed from the timing of the end of imaging detection (step S133). If the control circuit 6 determines that the first predetermined time has not elapsed from the timing of the end of imaging detection (step S133: No), it determines again whether or not the first predetermined time has elapsed from the timing of the end of imaging detection (step S133). If the control circuit 6 determines that the first predetermined time has elapsed from the timing of the end of imaging detection (step S133: Yes), an instruction to start imaging detection is output to the imaging pixel 3A (step S134). Note that although the processes in steps S133 and S134 were executed by the control circuit 6, they may also be executed by the control device 10.

[0069] Next, the imaging unit 20 controls the imaging pixel 3A to begin accumulating charge, similar to step S117 (step S135). Subsequently, the control circuit 6 determines whether or not a second predetermined time has elapsed (step S136). For example, in the process of step S136, the second predetermined time is the elapsed time from the start timing to the end timing of imaging detection when the imaging unit 20 is controlled to perform imaging detection for the first time. For example, the control circuit 6 acquires the second predetermined time based on the stored imaging time information.

[0070] If the control circuit 6 determines that the second predetermined time has not elapsed (step S136: No), it determines again whether the second predetermined time has elapsed (step S136). If the control circuit 6 determines that the second predetermined time has elapsed (step S136: Yes), the imaging pixel 3A is controlled to terminate imaging detection (step S137). Subsequently, the imaging unit 20 controls the imaging pixel 3A to terminate charge accumulation, similar to step S129 (step S138). Subsequently, the imaging unit 20 controls the imaging pixel 3A to output an imaging signal, similar to step S130 (step S139). Subsequently, the imaging signal is transferred to the control device 10 by the control circuit 6 (step S140). Subsequently, the control circuit 6 determines whether a predetermined number of imaging detections have been performed (step S141). If the control circuit 6 determines that a predetermined number of imaging detections have not been performed (step S141: No), it is determined again whether the first predetermined time has elapsed (step S133). If the control circuit 6 determines that a predetermined number of imaging detections have been performed (step S141: Yes), the first process is terminated.

[0071] Next, the control device 10 determines whether or not an imaging signal has been received (step S142). If it is determined that an imaging signal has been received (step S142: Yes), the control device 10 determines whether or not a predetermined number of imaging signals have been acquired (step S143). If the control device 10 determines that no imaging signal has been received (step S142: No), or if the control device 10 determines that no predetermined number of imaging signals have been acquired (step S143: No), it is determined again whether or not an imaging signal has been received (step S142). If the control device 10 determines that a predetermined number of imaging signals have been acquired (step S143: Yes), the first process is terminated.

[0072] As described above, in steps S133 to S143, if the control unit 30 controls the imaging unit 20 to perform imaging detection in the first process for each subsequent time, the start and end timings of imaging detection are determined based on the imaging time information acquired when imaging detection was performed for the first time. [Operation and Effects]

[0073] In the intraoral imaging system 100, when the control unit 30 controls the imaging unit 20 to perform imaging detection for the first time in the first processing, it determines the start and end timings of imaging detection based on the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection for the first time. This allows the control unit 30 to appropriately determine the start and end timings of imaging detection according to the imaging conditions in the first imaging detection without controlling the radiation source 200, and to acquire a two-dimensional image with high accuracy in the first imaging detection. Furthermore, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection in the first processing, it determines the end timing of imaging detection based on the imaging time information obtained when imaging detection was performed for the first time. This allows the control unit 30 to acquire a two-dimensional image with high accuracy in each subsequent imaging detection without controlling the radiation source 200. As a result, the control unit 30 can acquire multiple two-dimensional images with high accuracy without controlling the radiation source 200. Therefore, the intraoral imaging system 100 can accurately acquire multiple two-dimensional images while suppressing the complexity of system construction.

[0074] In the intraoral imaging system 100, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection in the first process, it determines the timing of the end of imaging detection based on imaging time information. As a result, for example, the timing of the end of each subsequent imaging detection is determined based on the elapsed time from the start to the end of the imaging detection performed for the first time. This allows the control unit 30 to appropriately determine the timing of the end of each subsequent imaging detection, taking into account the imaging conditions in the first imaging detection, without controlling the radiation source 200. As a result, the control unit 30 can easily and accurately acquire two-dimensional images in each subsequent imaging detection.

[0075] In the comparative intraoral imaging system, the dose of radiation emitted to the imaging unit is controlled in order to appropriately adjust the patient's radiation exposure and acquire images with an appropriate signal-to-noise ratio. Specifically, the timing of the start and end of imaging detection in the imaging unit, the timing of the rise and fall of the radiation waveform, and the timing when the radiation dose becomes constant are synchronized with high precision. If these timings are not synchronized, the dose of radiation emitted to the imaging unit may be excessive or insufficient, or the detection of radiation may fail, resulting in the output of an inappropriate image. In contrast, in the intraoral imaging system 100 described above, the imaging unit 20 does not need to control the radiation source 200, so the high-precision synchronization control described above is unnecessary. Furthermore, in the intraoral imaging system 100, only the imaging unit 20 is controlled by the control unit 30, so multiple imaging detections can be performed more quickly. As a result, the complexity of the design of the intraoral imaging system 100 can be suppressed. This makes it possible to suppress the high cost (design cost) of the intraoral imaging system 100, as well as the complexity of calibration and maintenance of the intraoral imaging system 100.

[0076] In the intraoral imaging system 100, when the imaging unit 20 is controlled by the control unit 30 to perform imaging detection on each subsequent imaging detection, the start and end timings of imaging detection are determined based on imaging time information. This allows the accumulation period T1 in each imaging detection to be aligned with high accuracy. Furthermore, compared to the case where the imaging unit 20 is controlled by the control unit 30 to perform imaging detection on the first attempt, the number of communications between the control unit 30 and the imaging unit 20 can be reduced. And, compared to the case where the imaging unit 20 is controlled by the control unit 30 to perform imaging detection on the first attempt, the time required for processing such as calculating the integrated value S2 of the monitor signal S1 can be reduced, thus reducing the time required for processing performed by the control unit 30.

[0077] In the intraoral imaging system 100, the control unit 30 controls the imaging unit 20 in the first process to perform imaging background detection at least once during periods when imaging detection is not being performed. Then, in the second process, the control unit 30 generates multiple two-dimensional images based on the imaging background signal and multiple imaging signals. As a result, for example, each of the multiple two-dimensional images is generated based on multiple signals obtained by subtracting the background signal from each of the multiple imaging signals. Consequently, it is possible to generate multiple two-dimensional images in which the background influence of the imaging pixels 3A is suppressed.

[0078] In the intraoral imaging system 100, the control unit 30 determines the timing of the start of the first imaging detection based on the timing when the value obtained by subtracting the intensity of the monitor background signal (obtained by controlling the imaging unit 20 to perform monitor background detection for the first time) from the intensity of the monitor signal S1 (obtained by controlling the imaging unit 20 to perform monitor detection for the first time) reaches a first threshold V1. This makes it possible to suppress the influence of the background of the monitor pixels 3B when determining the timing of the start of the first imaging detection based on the monitor signal S1. As a result, when the control unit 30 controls the imaging unit 20 to perform imaging detection for the first time, imaging detection can be more reliably started during the period when radiation R is being emitted.

[0079] In the intraoral imaging system 100, the control unit 30 controls the imaging unit 20 in the first process to perform monitor detection once. The control unit determines the timing of the end of the first imaging detection based on the timing when the accumulated value of the monitor signal S1 acquired after the start of the first imaging detection reaches the second threshold V2. This allows the first imaging detection to be terminated at an appropriate timing according to the imaging conditions of the first imaging detection.

[0080] In the intraoral imaging system 100, the first threshold V1 is smaller than the second threshold V2. This allows imaging detection to start earlier depending on the timing of radiation R emission. This reduces the radiation exposure of the target object T.

[0081] In the intraoral imaging system 100, the control unit 30 includes a control device 10 located outside the housing 8. This allows for the accurate acquisition of multiple two-dimensional images while suppressing the complexity of system construction when the control unit 30 includes a control device 10 located outside the housing 8.

[0082] In the intraoral imaging system 100, the control unit 30 includes a control circuit 6 located within the housing 8. This allows for the accurate acquisition of multiple two-dimensional images while suppressing the complexity of system construction when the control unit 30 includes a control circuit 6 located within the housing 8. [First Modified Example]

[0083] The first process of the first modified example is the same as the first process described above in that, when the control unit 30 controls the imaging unit 20 to perform imaging detection for the first time, the start and end timings of imaging detection are determined based on the monitor signal S1 (first monitor signal). However, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent time, the start and end timings of imaging detection are determined based on the monitor signal S1 (second monitor signal).

[0084] In the first process of the first modification, unlike the first process described above, the radiation source 200 may emit radiation R at a predetermined period, or, similar to the first process described above, it may continuously emit radiation R of a constant intensity to the object T. In the example shown in Figure 11, the radiation source 200 turns off the emission of radiation R while changing the incident angle of radiation R to the object T, and turns on the emission of radiation R while not changing the incident angle of radiation R to the object T.

[0085] The first process of the first modified example will be described with reference to Figure 11. After the control device 10 sends the instruction to start the first monitor detection C1 to the control circuit 6, the instruction to start reading the first imaging signal C4 is sent to the control circuit 6, and the process until the first reading period T2 begins is the same as the first process described above as shown in Figure 4.

[0086] In the first modification, unlike the first process described above shown in Figure 4, the following process is performed. When the first readout period T2 ends, the control device 10 sends a command C1 to start the second monitor detection to the control circuit 6, and the control circuit 6 controls the imaging unit 20 to start the second monitor detection. As a result, the monitor signal S1 is periodically acquired during the second monitor detection. Here, since the imaging pixel 3A and the monitoring pixel 3B share an output line to the control circuit 6 (see Figure 3), the monitoring pixel 3B continues to discard the monitor signal S1 while the imaging signal is output from the imaging pixel 3A to the control circuit 6 (readout period T2).

[0087] Next, when the radiation source 200 starts emitting radiation, the control device 10 sends a start instruction C2 for the second imaging detection to the control circuit 6, depending on the timing when the intensity of the monitor signal S1 exceeds the first threshold V1. Subsequently, the control circuit 6 controls the imaging unit 20 to start the second imaging detection, and the second accumulation period T1 begins. Next, the control device 10 sends an instruction C3 to the control circuit 6, which includes an instruction to end the second monitoring detection and an instruction to end the second imaging detection, depending on the timing when the calculated integrated value S2 of the monitor signal S1 reaches the second threshold V2. Subsequently, the control device 10 sends a start instruction C4 for reading out the imaging signal to the control circuit 6. Subsequently, the control circuit 6 begins the second reading period T2. The third and subsequent imaging detections are performed in the same manner as the second imaging detection.

[0088] The first process of the first modified example will be described in detail with reference to Figure 12. As shown in Figure 12, the first process of the first modified example is the same as the first process described above in that steps S100 to S132 are performed, but it differs from the first process described above in that steps S133 to S143 are not performed, and steps S201 to S203 are performed.

[0089] If the control device 10 determines that an imaging signal has been received (step S132: Yes), the control device 10 determines whether a predetermined number of imaging signals have been acquired (step S201). If the control device 10 determines that a predetermined number of imaging signals have been acquired (step S201: Yes), the first process is terminated.

[0090] If the control device 10 determines that a predetermined number of imaging signals have not been acquired (step S201: No), a monitor detection start instruction is sent to the control circuit 6 (step S202). Subsequently, the control circuit 6 controls the monitor pixel 3B to start monitor detection (step S203). For example, in the process of step S203, the process of periodically outputting the monitor signal S1 to the control circuit 6 by the monitor pixel 3B (steps S01 to S05) is resumed. Subsequently, as shown in Figure 7, the control device 10 sends a signal again requesting the transmission of the monitor signal S1 (step S109).

[0091] As described above, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection, the start and end timings of imaging detection are determined based on the monitor signal S1. For example, in the process of steps S109 to S117 after the processing of steps S201 to S203 has been executed, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection, the start timing of imaging detection is determined based on the monitor signal S1. As an example, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection, the imaging unit 20 is controlled to perform monitor detection for each subsequent imaging detection. Then, in the first process, the control unit 30 determines the start timing of each subsequent imaging detection according to the timing when the monitor signal S1 acquired by controlling the imaging unit 20 to perform monitor detection for each subsequent imaging detection reaches the first threshold V1.

[0092] Furthermore, for example, in the processing of steps S118 to S124 after the processing of steps S201 to S203 has been executed, if the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection, the timing of the end of imaging detection is determined based on the monitor signal. As an example, the control unit 30 determines the timing of the end of each subsequent imaging detection according to the timing when the integrated value of the value obtained by subtracting the intensity of the monitor background signal from the intensity of the monitor signal S1 reaches the second threshold V2.

[0093] As described above, in the first modified intraoral imaging system 100, when the control unit 30 controls the imaging unit 20 to perform imaging detection for the first time in the first process, it determines the start and end timings of imaging detection based on the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection for the first time. This allows the control unit 30 to appropriately determine the start and end timings of imaging detection according to the imaging conditions in the first imaging detection without controlling the radiation source 200, and to acquire a two-dimensional image with high accuracy in the first imaging detection. Furthermore, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent time in the first process, it determines the start and end timings of imaging detection based on the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection for each subsequent time. This allows the control unit 30 to acquire a two-dimensional image with high accuracy in each subsequent imaging detection without controlling the radiation source 200. As described above, the control unit 30 can accurately acquire multiple two-dimensional images without controlling the radiation source 200 if the imaging conditions change before the timing of the first imaging detection. Therefore, the first modified intraoral imaging system 100 can accurately acquire multiple two-dimensional images while suppressing the complexity of system construction.

[0094] In the first modified intraoral imaging system 100, the control unit 30, in the first process, when controlling the imaging unit 20 to perform imaging detection for each subsequent imaging detection, determines the start and end timings of the imaging detection based on the monitor signal S1. This determines the start and end timings of each subsequent imaging detection, taking into account the imaging conditions for each subsequent imaging detection. As a result, the control unit 30 can appropriately determine the start and end timings of each subsequent imaging detection, taking into account the imaging conditions for each subsequent imaging detection, such as the incident angle of radiation R on the target object T and the intensity of radiation R incident on the imaging unit 20, without controlling the radiation source 200. Therefore, compared to the case where the control unit 30 determines the end timing of the imaging detection based on imaging time information as in the above embodiment, a two-dimensional image can be acquired with even greater accuracy in each subsequent imaging detection.

[0095] In the first modified intraoral imaging system 100, the control unit 30 determines the timing of the start of each subsequent imaging detection in the first process, according to the timing when the value obtained by subtracting the intensity of the monitor background signal obtained by controlling the imaging unit 20 to perform monitor background detection in each subsequent imaging detection from the intensity of the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection in each subsequent imaging detection reaches a first threshold V1. This makes it possible to more reliably start imaging detection during the period when radiation R is being emitted when the control unit 30 controls the imaging unit 20 to perform imaging detection for the second time.

[0096] In the first modified intraoral imaging system 100, the control unit 30 controls the imaging unit 20 to perform monitor detection for each subsequent imaging detection. The control unit determines the timing of the end of each subsequent imaging detection based on the timing at which the accumulated value S2 of the monitor signals S1 acquired after the start of each subsequent imaging detection reaches the second threshold V2. This allows each subsequent imaging detection to be terminated at an appropriate timing according to the imaging conditions for each subsequent imaging detection. Furthermore, the design of the control circuit 6 is simplified. [Second Modified Example]

[0097] The first process of the second modified example is the same as the first process described above in that, when the imaging unit 20 is controlled by the control unit 30 to perform imaging detection for the first time, the start and end timings of imaging detection are determined based on the monitor signal S1 (first monitor signal), and when the imaging unit 20 is controlled to perform imaging detection for the second time and onward, the end timing of imaging detection is determined based on the imaging time information. However, it differs from the first process described above in that the storage period T1 overlaps with the readout period T2.

[0098] As shown in Figure 13, the circuit of the imaging pixel 3A of the image sensor 3 in the second modified intraoral imaging system 100 includes a readout transistor 31, a reset transistor 32, a charge accumulation control transistor 33, a charge retention transistor 34, a multiplication transistor 35, a photodiode (PD) 36, and a floating diffusion (FD) 37. In the imaging pixel 3A, when transistors 31 and 35 are turned ON and transistors 32, 33, and 34 are turned OFF, charge accumulation in the PD 36 and output of an electrical signal from the FD 37 can be performed simultaneously. As a result, the imaging pixel 3A can read out the charge accumulated in the previous imaging detection while performing imaging detection. The transistors used in Figure 13 are, for example, MOS-FETs.

[0099] The monitor pixel 3B may have the same configuration as the imaging pixel 3A, or it may have a different configuration from the imaging pixel 3A. For example, if the monitor pixel 3B has a different configuration from the imaging pixel 3A, the monitor pixel 3B may include a photodiode and a charge amplifier that converts the charge output from the photodiode into a voltage signal (monitor signal S1).

[0100] The outline of the first process of the second modified example will now be described. As shown in Figure 14, after the control device 10 sends the instruction to start the first monitor detection C1 to the control circuit 6, the control device 10 sends the instruction to start reading the first imaging signal C4 to the control circuit 6, and the process until the control circuit 6 starts the first reading period T2 is the same as the first process described above as shown in Figure 4.

[0101] In the first process of the second modified example, unlike the first process described above shown in Figure 4, the following process is performed. The control device 10 sends a start instruction C2 for the second imaging detection to the control circuit 6 when a third elapsed time has elapsed from the end of the first imaging detection. Subsequently, the control circuit 6 starts the second imaging detection and the second storage period T1 begins. At this time, the control circuit 6 controls the imaging unit 20 so that the second imaging detection starts before the end of the first readout period T2. The third predetermined time is longer than the time required to change the incident angle of radiation R on the object T. Therefore, at this time, the incident angle of radiation R on the object T is changed before the second imaging detection starts.

[0102] Next, the control circuit 6 terminates the first readout period T2. Then, the control circuit 6 terminates the second imaging detection, ending the second storage period T1. At this time, the control circuit 6 controls the timing of the termination of the second imaging detection so that the length of the second storage period T1 is the same as the length of the first storage period T1. Next, the control circuit 6 controls the imaging unit 20 to start reading out the imaging signal. At this time, the incident angle of radiation R on the object T is changed. Next, the control circuit 6 controls the imaging unit 20 to start the third imaging detection when a third predetermined time has elapsed from the timing of the termination of the second imaging detection. The third and subsequent imaging detections are performed in the same manner as the second imaging detection.

[0103] Referring to Figure 15, the first process of the second modified example will be described in detail. As shown in Figure 15, the first process of the second modified example is the same as the first process described above in that steps S100 to S132 and steps S134 to S143 are performed, but it differs from the first process described above in that step S133 is not performed, and steps S301 and S302 are performed.

[0104] First, after the process in step S132 is executed, the control circuit 6 determines whether a third predetermined time has elapsed since the end of the imaging detection (step S301). Subsequently, the processes in steps S134 to S138 are executed, and after the process in step S139 is started, the control circuit 6 determines whether the imaging detection that just finished was the last imaging detection (step S302).

[0105] If the control circuit 6 does not determine that the most recently completed imaging detection is the last imaging detection (step S302: No), it is determined again whether the third progress information has elapsed (step S301), and the processes in steps S134 to S138 are executed again. At this time, the imaging pixel 3A simultaneously executes the process of accumulating charge in the second imaging detection (second step S135) and the process of reading out the charge accumulated in the first imaging detection (first step S139). The latter process (first step S139) is completed before the former process (second step S135) is completed. Then, the control circuit 6 transfers the imaging signal to the control device 10. Therefore, in each of the multiple imaging detections, the imaging signal is output from the imaging pixel 3A to the control circuit 6 and transferred to the control device 10.

[0106] If the control circuit 6 determines that the most recently completed imaging detection was the last imaging detection (step S302: Yes), the process in step S140 is executed. In other words, the imaging signal output from the imaging pixel 3A to the control circuit 6 during the last imaging detection is also transferred to the control device 10. [Third Modification]

[0107] The first process of the third modified example is the same as the first process described above in that, when the imaging unit 20 is controlled by the control unit 30 to perform imaging detection for the first time, the start and end timings of imaging detection are determined based on the monitor signal S1 (first monitor signal), and when the imaging unit 20 is controlled to perform imaging detection for the second time and onward, the end timing of imaging detection is determined based on the imaging time information. However, it differs from the first process described above in that, when the imaging unit 20 is controlled to perform imaging detection for the second time and onward, the control device 10 transmits start and end instructions for imaging detection to the control circuit 6, thereby controlling the imaging unit 20 to start and end imaging detection.

[0108] The outline of the first process of the third modified example will now be described. As shown in Figure 16, after the control device 10 sends a start instruction C1 for the first monitor detection to the control circuit 6, the control device 10 sends a start instruction C4 for the reading of the first imaging signal to the control circuit 6, and the process until the control circuit 6 starts the first reading period T2 is the same as the first process described above as shown in Figure 4.

[0109] In the first process of the third modified example, unlike the first process described above shown in Figure 4, the following process is executed. The control device 10 sends a start instruction C2 for the second imaging detection to the control circuit 6 when a first predetermined time has elapsed from the timing of the end of the first imaging detection. Subsequently, the control circuit 6 starts the second imaging detection and the second storage period T1 begins. At this time, the control circuit 6 controls the imaging unit 20 to start the second imaging detection after the end of the first readout period T2. Subsequently, the control device 10 sends an instruction C6 to the control circuit 6, which includes an instruction to end the imaging detection and an instruction to start reading the imaging signal. Subsequently, the control circuit 6 ends the second storage period T1 and the second imaging detection ends. Subsequently, when a first predetermined time has elapsed from the timing of the end of the second imaging detection, a start instruction C2 for the third imaging detection is sent to the control circuit 6. The third and subsequent imaging detections are executed in the same manner as the second imaging detection.

[0110] Referring to Figure 17, the first process of the third modified example will be described in detail. As shown in Figure 17, the first process of the third modified example is the same as the first process described above in that it performs steps S100 to S132, S134, S135, S137 to S140, S142, and S143, but differs from the first process described above in that it does not perform steps S133, S136, and S141, but performs steps S401 to S404.

[0111] First, after the process in step S132 is executed, the control device 10 determines whether a first predetermined time has elapsed since the end of the imaging detection (step S401). Subsequently, the control device 10 sends an instruction to start imaging detection to the control circuit 6 (step S402). After that, the processes in steps S134 and S135 are executed.

[0112] Next, the control device 10 determines whether a second predetermined time has elapsed since the start of image detection (step S403). If the control device 10 determines that a second predetermined time has not elapsed since the start of image detection (step S403: No), the control device 10 determines again whether a second predetermined time has elapsed since the start of image detection. If the control device 10 determines that a second predetermined time has elapsed since the start of image detection (step S403: Yes), an instruction to end image detection is sent to the control circuit 6. After that, the processes in steps S137 to S140, S142, and S143 are executed. [Fourth Modification]

[0113] In the intraoral imaging system 100 of this embodiment, when the imaging unit 20 is controlled by the control unit 30 to perform imaging detection for each subsequent imaging detection, the timing for starting imaging detection is determined based on the timing after a first predetermined time has elapsed since the end of the previous imaging detection. However, the timing for starting imaging detection may be determined based on the monitor signal S1.

[0114] In the fourth modified intraoral imaging system 100, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent imaging detection in the first process, it may determine the start timing of imaging detection based on the monitor signal S1 and the end timing of imaging detection based on the imaging time information. This allows the control unit 30 to more reliably start each subsequent imaging detection during the period when radiation R is emitted, without controlling the radiation source 200. Furthermore, the control unit 30 can appropriately determine the end timing of each subsequent imaging detection, taking into account the imaging conditions in the first imaging detection, without controlling the radiation source 200. As a result, the control unit 30 can acquire two-dimensional images with high accuracy in each subsequent imaging detection.

[0115] For example, in the fourth modified intraoral imaging system 100, the radiation source 200 emits radiation R at a predetermined period, and one example is a pulsed radiation source. In this case, when the control unit 30 controls the imaging unit 20 to perform imaging detection for each subsequent time in the first process, it determines the timing of the start of imaging detection based on the monitor signal S1. This makes it possible to more reliably start imaging detection at the timing when radiation R is emitted from the radiation source 200. The control unit 30 also acquires a second predetermined time based on the imaging time information and determines the timing of the end of imaging detection based on the second predetermined time. [Fifth Modified Example]

[0116] In the first modified intraoral imaging system 100, when the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent imaging detection in the first process, it determines the start and end timings of imaging detection based on the monitor signal S1 (second monitor signal). However, when the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent imaging detection from the (n+1)th time onward (where n is an integer of 2 or more), it may determine the end timing of imaging detection based on imaging time information.

[0117] In the fifth modified intraoral imaging system 100, the control unit 30, in the first process, may determine the start and end timings of imaging detection based on the monitor signal S1 when controlling the imaging unit 20 to perform imaging detection for each of the second to nth times, and may determine the end timing of imaging detection based on imaging time information when controlling the imaging unit 20 to perform imaging detection for each of the (n+1)th and subsequent times. This allows the control unit 30 to acquire two-dimensional images with even greater accuracy compared to the case where the control unit 30 determines the end timing of imaging detection based on imaging time information for each of the second to nth imaging detections. Furthermore, the control unit 30 can easily and accurately acquire two-dimensional images for each of the (n+1)th and subsequent imaging detections. As a result, the control unit 30 can acquire two-dimensional images with high accuracy for each of the second and subsequent imaging detections. [Sixth Modified Example]

[0118] In the fifth modified example of the intraoral imaging system 100, when the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent (n+1)th time in the first process, it determines the timing of the end of imaging detection based on imaging time information. However, when the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent (n+k) time (k is an integer of 2 or more), it may determine the timing of the start and end of imaging detection based on the monitor signal S1 (second monitor signal).

[0119] In the sixth modified intraoral imaging system 100, the control unit 30 may, in the first process, control the imaging unit 20 to perform monitor detection on each subsequent imaging detection when controlling the imaging unit 20 to perform monitor detection on each subsequent imaging detection when controlling the imaging unit 20 to perform monitor detection on each subsequent imaging detection when controlling the imaging unit 20 to perform monitor detection on each subsequent imaging detection when the difference between the exposure time information calculated based on the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection on each subsequent imaging detection reaches a third threshold, determine the start and end timing of imaging detection based on the monitor signal S1. As a result, the control unit 30 determines the start and end timing of imaging detection based on the monitor signal S1 when there is a significant change in the imaging conditions during each subsequent imaging detection, for example, when there is a significant change in the intensity of the radiation R incident on the imaging unit 20. As a result, the control unit 30 can reliably and accurately acquire two-dimensional images even when there is a significant change in the imaging conditions during each subsequent imaging detection.

[0120] For example, the control unit 30 calculates exposure time information indicating the appropriate exposure time for each imaging detection from the (n+1)th time onward, based on the monitor signal S1 acquired by the monitor detection from the (n+1)th time onward. When the difference between the calculated exposure time information and the imaging time information reaches a third threshold, the control unit 30 determines the start and end timings of the next imaging detection based on the monitor signal S1. The exposure time information is information indicating the elapsed time from the start timing of the (n+1)th imaging detection when the imaging unit 20 is controlled to perform imaging detection on the (n+1)th time, to the timing when the integrated value S2 of the monitor signal S1 acquired after the start timing of the (n+1)th imaging detection reaches a second threshold V2. The third threshold is preset. [Modified Example]

[0121] This disclosure is not limited to the examples described above. For example, in the intraoral imaging system 100 described above, if the control unit 30 controls the imaging unit 20 to perform imaging detection in each subsequent imaging detection in the first process, it only needs to determine the start and end timings of imaging detection based on at least one of the imaging time information and the monitor signal S1. Even in this case, the control unit 30 can acquire a two-dimensional image accurately in each subsequent imaging detection without controlling the radiation source 200.

[0122] In the intraoral imaging system 100 described above, the control unit 30 performs a first process of acquiring multiple imaging signals by controlling the imaging unit 20 to perform imaging detection multiple times, a second process of generating multiple two-dimensional images based on the multiple imaging signals, and a third process of generating a three-dimensional image based on the multiple two-dimensional images. However, it is sufficient to perform at least the first and second processes. For example, the control unit 30 may perform a process other than the third process instead of the third process.

[0123] For example, in the first process, the incident angle of radiation R on the object T may be constant. In this case, the control unit 30 may perform the processes described in the first to fourth examples below. In the first example, in the first process, the control unit 30 may acquire multiple imaging signals by controlling the imaging unit 20 to perform imaging detection multiple times while changing the accumulation period T1, and in the second process, after generating multiple two-dimensional images based on the multiple imaging signals, an HDR image may be generated by performing high dynamic range (HDR) synthesis on the multiple two-dimensional images.

[0124] As a second example, the control unit 30 may, in the second processing, generate multiple two-dimensional images based on multiple imaging signals, and then select the clearest two-dimensional image from among the multiple two-dimensional images. In this case, when the imaging unit 20 is controlled to perform imaging detection, it is possible to obtain a two-dimensional image in which blurring caused by the movement of the object (for example, the patient's head) is suppressed.

[0125] As a third example, the control unit 30 may, in the first process, control the imaging unit 20 to perform imaging detection multiple times while changing the analog gain of the imaging unit 20 to acquire multiple imaging signals, and in the second process, generate multiple two-dimensional images based on the multiple imaging signals, and then select a two-dimensional image with appropriate brightness from the multiple two-dimensional images.

[0126] In a fourth example, the control unit 30 acquires multiple imaging signals by controlling the imaging unit 20 to perform imaging detection multiple times with an accumulation period T1 of a certain length in the first process, and in the second process generates multiple two-dimensional images based on the multiple imaging signals, and then synthesizes the multiple two-dimensional images to generate a single two-dimensional image. In this case, it is possible to generate a single two-dimensional image with reduced intensity of randomly occurring noise.

[0127] In the intraoral imaging system 100 described above, the control unit 30 controlled the imaging unit 20 in the first process to perform imaging background detection at least once during periods when imaging detection is not being performed. However, in the first process, the control unit 30 may control the imaging unit 20 to perform imaging background detection multiple times in association with each imaging detection during periods when imaging detection is not being performed. In the second process, the control unit 30 may generate multiple two-dimensional images based on multiple imaging background signals and multiple imaging signals. This allows, for example, the generation of multiple two-dimensional images to be based on signals obtained by subtracting each of the multiple background signals from each of the multiple imaging signals. As a result, multiple two-dimensional images can be generated in which the influence of the background of the imaging pixels 3A in each imaging detection from the first detection onward is suppressed. Furthermore, when multiple imaging detections are performed consecutively in a short time, changes in the background (dark current) of the imaging pixels are likely to occur due to the afterglow and heat of the scintillator. In this case, it was sometimes not possible to generate multiple two-dimensional images with high accuracy. In contrast, the modified intraoral imaging system 100 described above suppresses the background influence of the imaging pixels 3A during each of the multiple imaging detections when generating multiple two-dimensional images. This suppresses the afterglow and heat effects of the scintillator 5 when multiple imaging detections are performed consecutively in a short time. As a result, multiple two-dimensional images can be generated with even greater accuracy.

[0128] For example, in the first process of the first modified example shown in Figure 11, the imaging unit 20 is controlled to perform imaging background detection during the period T3 when no radiation is emitted, before the start of each subsequent imaging detection. Then, in the second process, the control unit 30 generates each of the multiple two-dimensional images based on the values ​​obtained by subtracting the intensity of each of the multiple imaging background signals from the intensity of each of the multiple imaging signals.

[0129] In the intraoral imaging system 100 described above, when the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent imaging detection in the first process, and controls the imaging unit 20 to perform monitor detection on the first imaging detection, it controls the imaging unit 20 to perform monitor background detection on the first imaging detection before performing monitor detection on the first imaging detection, but it is not limited to this. When the control unit 30 controls the imaging unit 20 to perform imaging detection on each subsequent imaging detection in the first process, and controls the imaging unit 20 to perform monitor detection on each subsequent imaging detection, it may also control the imaging unit 20 to perform monitor background detection on each subsequent imaging detection before performing monitor detection on each subsequent imaging detection. In this case, the control unit 30 may determine the start timing of each subsequent imaging detection in the first process, based on the timing when the value obtained by subtracting the intensity of the monitor background signal obtained by controlling the imaging unit 20 to perform monitor background detection in each subsequent imaging detection from the intensity of the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection in each subsequent imaging detection reaches a first threshold V1. In this case, when the control unit 30 determines the start timing of each subsequent imaging detection based on the monitor signal S1, the influence of the background of the monitor pixels 3B corresponding to each subsequent imaging detection can be suppressed. As a result, when the control unit 30 controls the imaging unit 20 to perform imaging detection in each subsequent imaging detection, imaging detection can be started more reliably during the period when radiation R is emitted.

[0130] For example, in the first process of the first modified example shown in Figure 12, after the processes of steps S201 to S203 are executed, the process of step S100 may be executed instead of the process of step S109.

[0131] In the intraoral imaging system 100 described above, the control unit 30 controls the imaging unit 20 to perform imaging background detection at least once before the timing of the start of radiation emission R in the first process. However, it is sufficient if imaging background detection is performed at least once during the period when imaging detection is not being performed.

[0132] In the intraoral imaging system 100 described above, the control unit 30 determines the timing of the start of the first imaging detection based on the timing when the value obtained by subtracting the intensity of the monitor background signal obtained by controlling the imaging unit 20 to perform monitor background detection for the first time from the intensity of the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection for the first time reaches a first threshold V1. However, it is sufficient to determine the timing of the start of the first imaging detection based on the monitor signal S1.

[0133] In the intraoral imaging system 100 described above, the control unit 30 controls the imaging unit 20 in the first process to perform monitor detection once, and determines the timing of the end of the first imaging detection according to the timing when the accumulated value S2 of the monitor signal S1 acquired after the start of the first imaging detection reaches the second threshold V2. However, it is sufficient to determine the timing of the end of the first imaging detection based on the monitor signal S1.

[0134] In the intraoral imaging system 100 described above, the control unit 30 determines the start timing of each subsequent imaging detection in the first process by subtracting the intensity of the monitor background signal obtained by controlling the imaging unit 20 to perform monitor background detection in each subsequent imaging detection from the intensity of the monitor signal S1 obtained by controlling the imaging unit 20 to perform monitor detection in each subsequent imaging detection, according to the timing when the value obtained reaches a first threshold V1. However, it is sufficient to determine the start timing of subsequent imaging detection based on the monitor signal S1.

[0135] In the intraoral imaging system 100 described above, when the control unit 30 controls the imaging unit 20 to perform imaging detection in the first process so that imaging detection is performed in each subsequent imaging detection, the timing of the end of each subsequent imaging detection is determined according to the timing when the accumulated value S2 of the monitor signal S1 acquired after the start timing of each subsequent imaging detection reaches the second threshold V2. However, it is sufficient to determine the timing of the end of each subsequent imaging detection based on the monitor signal S1.

[0136] In the intraoral imaging system 100 described above, the first threshold V1 is smaller than the second threshold V2, but may be larger than the second threshold V2, or may be the same as the second threshold V2.

[0137] In the intraoral imaging system 100 described above, the control unit 30 was composed of at least a control device 10 and a control circuit 6. However, the control unit 30 may be composed only of the control device 10 located outside the housing 8, or it may be composed only of the control circuit 6 located inside the housing 8.

[0138] In the imaging system S described above, the incident angle of radiation R on the object T is changed by the movement of a single radiation source 200, but the system is not limited to this. For example, the imaging system S may have multiple radiation sources 200 that are arranged at different positions from each other and emit radiation R on the object T, and the incident angle of radiation R on the object T may be changed by changing the radiation source 200 that emits radiation R to another radiation source 200. As an example, multiple radiation sources 200 are arranged in an array, and the incident angle of radiation R on the object T is changed sequentially by sequentially emitting radiation R from the multiple radiation sources 200.

[0139] In the above embodiment, as shown in Figure 3, the imaging pixel 3A and the monitoring pixel 3B shared an output line to the control circuit 6. However, the output line of the imaging pixel 3A and the output line of the monitoring pixel 3B may each be configured as separate, independent output lines. In this case, the ASIC of the image sensor 3 can simultaneously output the imaging signal from the imaging pixel 3A and the monitor signal S1 from the monitoring pixel 3B.

[0140] In the above embodiment, the ASIC of the image sensor 3 controlled the monitor pixel 3B to periodically read the monitor signal S1 with the switch SW2 always set to ON during a predetermined period when no radiation R was being emitted. However, the monitor signal S1 may be periodically output from the monitor pixel 3B by setting the switch SW2 to ON at a predetermined interval (i.e., periodically switching the switch SW2 between the ON state and the OFF state).

[0141] 100...Intraoral imaging system, 3A...Imaging pixel, 3B...Monitoring pixel, 6...Control circuit, 8...Housing, 10...Control device, 20...Imaging unit, 30...Control unit, R...Radiation, S1...Monitoring signal, S2...Integrated value, T...Object, V1...First threshold, V2...Second threshold.

Claims

1. The device comprises an imaging unit that detects radiation transmitted through an object while positioned in the oral cavity, and a control unit that is electrically connected to the imaging unit and controls the imaging unit, wherein the imaging unit performs monitor detection to acquire a monitor signal relating to the dose of the radiation, and performs imaging detection multiple times to acquire multiple imaging signals relating to the image of the object, the control unit performs a first process of acquiring the multiple imaging signals by controlling the imaging unit to perform imaging detection multiple times, a second process of generating multiple two-dimensional images based on the multiple imaging signals, and a third process of generating a three-dimensional image based on the multiple two-dimensional images, and in the first process, when the control unit controls the imaging unit to perform imaging detection for the first time, it determines the start and end timing of the imaging detection based on the first monitor signal acquired as the monitor signal by controlling the imaging unit to perform monitor detection for the first time. In the first process, when the imaging unit is controlled to perform the imaging detection for each subsequent time, the intraoral imaging system determines the timing of at least one of the start and end of the imaging detection based on at least one of the imaging time information obtained when the imaging detection was performed for the first time, and the second monitor signal obtained as the monitor signal by controlling the imaging unit to perform the monitor detection for the second time and beyond.

2. The intraoral imaging system according to claim 1, wherein the imaging unit includes imaging pixels used for imaging detection, and performs imaging background detection to acquire an imaging background signal relating to the background of the imaging pixels, the control unit controls the imaging unit in the first process to perform imaging background detection at least once during periods when imaging detection is not being performed, and generates the plurality of two-dimensional images in the second process based on the imaging background signal and the plurality of imaging signals.

3. The intraoral imaging system according to claim 1, wherein the imaging unit includes imaging pixels used for imaging detection, and performs imaging background detection multiple times to acquire a plurality of imaging background signals relating to the background of the imaging pixels, the control unit controls the imaging unit in the first process to perform imaging background detection multiple times in association with each imaging detection during periods when imaging detection is not being performed, and generates a plurality of two-dimensional images in the second process based on the plurality of imaging background signals and the plurality of imaging signals.

4. The intraoral imaging system according to any one of claims 1 to 3, wherein the imaging unit includes monitor pixels used for monitor detection, and performs monitor background detection to acquire a monitor background signal relating to the background of the monitor pixels, and the control unit, in the first process, controls the imaging unit to perform monitor background detection for the first time before performing monitor detection for the first time if the imaging unit is controlled to perform imaging detection for the first time, and in the first process, the timing of the start of the first imaging detection is determined according to the timing when the value obtained by subtracting the intensity of the monitor background signal acquired by controlling the imaging unit to perform monitor background detection for the first time from the intensity of the first monitor signal reaches a first threshold.

5. The intraoral imaging system according to claim 4, wherein, in the first process, when the control unit controls the imaging unit to perform the imaging detection on each subsequent second and subsequent times, when the control unit controls the imaging unit to perform the monitor detection on each subsequent second and subsequent times, the control unit controls the imaging unit to perform the monitor background detection on each subsequent second and subsequent times before performing the monitor detection on each subsequent second and subsequent times, and in the first process, the timing of the start of each subsequent imaging detection is determined according to the timing when the value obtained by subtracting the intensity of the monitor background signal obtained by controlling the imaging unit to perform the monitor background detection on each subsequent second and subsequent times from the intensity of the second monitor signal reaches the first threshold.

6. The intraoral imaging system according to claim 4 or 5, wherein the control unit controls the imaging unit to perform the monitor detection once in the first process, and determines the timing of the end of the first imaging detection according to the timing at which the accumulated value of the first monitor signal acquired after the start of the first imaging detection reaches a second threshold.

7. In the first process, when the control unit controls the imaging unit to perform the imaging detection on each subsequent imaging detection, when the control unit controls the imaging unit to perform the monitor detection on each subsequent monitoring detection, the control unit controls the imaging unit to perform the monitor detection on each subsequent monitoring detection, and determines the timing of the end of each subsequent imaging detection on each subsequent imaging detection according to the timing at which the accumulated value of the second monitor signal acquired after the start timing of each subsequent imaging detection reaches the second threshold, as described in claim 6.

8. The intraoral imaging system according to claim 6 or 7, wherein the first threshold is smaller than the second threshold.

9. The intraoral imaging system according to any one of claims 1 to 8, wherein, in the first process, the control unit controls the imaging unit to perform the imaging detection on each subsequent imaging detection, and determines the timing of the termination of the imaging detection based on the imaging time information.

10. In the first process, if the control unit controls the imaging unit to perform the imaging detection on each subsequent imaging detection, the control unit determines the start and end timings of the imaging detection based on the second monitor signal, the intraoral imaging system according to any one of claims 1 to 8.

11. The intraoral imaging system according to any one of claims 1 to 8, wherein, in the first process, the control unit controls the imaging unit to perform the imaging detection on each subsequent imaging detection, determines the start timing of the imaging detection based on the second monitor signal, and determines the end timing of the imaging detection based on the imaging time information.

12. The intraoral imaging system according to any one of claims 1 to 8, wherein, in the first process, the control unit controls the imaging unit to perform the imaging detection on each of the nth (where n is an integer of 2 or more) imaging detections from the second time onward, and determines the start and end timings of the imaging detections based on the second monitor signal, and controls the imaging unit to perform the imaging detections on each of the (n+1)th and subsequent imaging detections, and determines the end timing of the imaging detections based on the imaging time information.

13. The intraoral imaging system according to claim 12, wherein the control unit controls the imaging unit to perform the monitor detection on each subsequent imaging detection in the first process, and when the control unit controls the imaging unit to perform the monitor detection on each subsequent imaging detection in the (n+1)th imaging detection, the control unit determines the start and end timing of the imaging detection based on the second monitor signal when the difference between the exposure time information calculated based on the second monitor signal obtained by controlling the imaging unit to perform the monitor detection on each subsequent imaging detection reaches a third threshold.

14. The intraoral imaging system according to any one of claims 1 to 13, further comprising a housing that houses the imaging unit, wherein the control unit includes a control device disposed outside the housing.

15. The intraoral imaging system according to any one of claims 1 to 14, further comprising a housing that houses the imaging unit, wherein the control unit includes a control circuit disposed within the housing.

Images