Imaging system and operating method thereof

Abstract

The invention discloses an imaging system and an operation method thereof. The imaging system comprises: a radiation source for transmitting a radiation beam toward a pet; an image sensor that captures an image of the pet based on an interaction between the radiation beam and the pet; and a cannula or strap. The sleeve or strap is used to secure the pet such that the pet remains stationary relative to the image sensor, and any straight line intersecting the pet's kidney or bladder, the image sensor, and the radiation source does not intersect any bone of the pet. The image sensor is mounted on the wall of the cannula or on the bandage. A cannula or strap is located between the image sensor and the radiation source.

Description

[Technical field]

[0001] The present invention relates to an imaging system and an operating method thereof, and more particularly to an imaging system capable of detecting stones in the bladder and kidney of a pet (such as a cat) and an operating method thereof. [Background technology]

[0002] The imaging system can include a radiation source and a radiation detector. The radiation source can send a radiation beam to an object located between the radiation source and the radiation detector; and the radiation detector can capture an image of the object based on the interaction between the radiation beam and the object. [Summary of the invention]

[0003] The present invention discloses an imaging system, which includes: a radiation source configured to send a radiation beam toward a pet; an image sensor configured to capture an image of the pet based on the interaction between the radiation beam and the pet; and a sleeve or a strap. The sleeve or the strap is configured to fix the pet so that the pet remains stationary relative to the image sensor used for imaging, and any straight line intersecting the kidney or bladder of the pet, the image sensor, and the radiation source does not intersect any bone of the pet. The image sensor is mounted on the wall of the sleeve or on the strap. The sleeve or the strap is located between the image sensor and the radiation source. The image sensor includes: M radiation detectors, M is a positive integer; and N input / output areas for the M radiation detectors, N is a positive integer. The N input / output areas are located at the edge of the image sensor. Each of the M radiation detectors comprises: a radiation absorbing layer including an electrode; a first voltage comparator configured to compare a voltage of the electrode with a first threshold; a second voltage comparator configured to compare the voltage with a second threshold; a counter configured to record the number of photons absorbed by the radiation absorbing layer; and a controller. The controller is configured to start a time delay from the time when the first voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold. The controller is configured to enable the second voltage comparator during the time delay, and the controller is configured to increase the number recorded by the counter by one if the second voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold.

[0004] In one aspect, the reference plane is parallel to the radiation receiving surface of the image sensor, and the straight line segments respectively connecting the two orthogonal projections of any two sensing elements of the M radiation detectors on the reference plane do not intersect with the orthogonal projections of any input / output areas for the M radiation detectors on the reference plane.

[0005] In one aspect, any straight line that intersects the radiation source and any sensing element of the M radiation detectors does not intersect any portion of any input / output region for any of the M radiation detectors.

[0006] In one aspect, the radiation beam is an X-ray beam having a photon energy less than 10 KeV.

[0007] In one aspect, each of the radiation detectors further comprises a capacitive module electrically connected to the electrode, and the capacitive module is configured to collect carriers from the electrode.

[0008] In one aspect, the controller is configured to enable the second voltage comparator when the time delay begins or ends.

[0009] In one aspect, each radiation detector further comprises a voltmeter, and the controller is configured to cause the voltmeter to measure the voltage when the time delay expires.

[0010] In one aspect, the controller is configured to determine the photon energy based on a value of the voltage measured at the expiration of the time delay.

[0011] In one aspect, the controller is configured to electrically connect the electrode to electrical ground.

[0012] In one aspect, at the expiration of the time delay, the rate of change of the voltage is substantially zero.

[0013] In one aspect, at the expiration of the time delay, the rate of change of the voltage is substantially non-zero.

[0014] In one aspect, the radiation absorbing layer comprises a diode.

[0015] In one aspect, the radiation absorbing layer comprises silicon, germanium, GaAs, CdTe, CdZnTe, or combinations thereof.

[0016] In one aspect, the system does not include a scintillator.

[0017] In one aspect, the radiation absorbing layer comprises an array of sensing elements.

[0018] In one aspect, the strap is configured to wrap around the abdominal area of ​​the pet.

[0019] The present invention discloses a method for operating the imaging system, which comprises: using the radiation source to generate a radiation beam, the radiation beam being directed toward the kidney or bladder of the pet fixed by the sleeve or the strap; and using the image sensor to capture an image of the kidney or the bladder based on the interaction between the radiation beam and the kidney or the bladder during exposure.

[0020] In one aspect, the value of a pixel of the image is related to a number registered by the counter of one of the M radiation detectors of the image sensor after exposure.

[0021] In one aspect, any straight line that intersects the kidney or the bladder, the image sensor, and the radiation source does not intersect any bone of the pet.

Brief Description of the Drawings

[0022] Figure 1A A semiconductor radiation detector according to an embodiment is schematically shown.

[0023] Figure 1B A semiconductor radiation detector 100 according to an alternative embodiment is shown.

[0024] Figure 2 According to the embodiment Figure 1A An exemplary top view of a portion of a detector in FIG.

[0025] Figure 3A and Figure 3B Each shows a Figure 1A or Figure 1B A diagram of the components of the detector's electronic system.

[0026] Figure 4 Schematically illustrates the temporal variation of a current flowing through an electrode of a diode or an electrical contact of a resistor exposed to radiation by a radiation absorbing layer according to an embodiment (upper curve) and the corresponding temporal variation of a voltage of the electrode (lower curve), wherein the current is caused by carriers generated by radiation particles incident on the radiation absorbing layer.

[0027] Figure 5 Schematically illustrating the Figure 4 The temporal variation of the current flowing through an electrode (upper curve) and the corresponding temporal variation of the voltage of the electrode (lower curve) caused by noise (eg, dark current) in an electronic system operating in the manner shown.

[0028] Figure 6 Schematically illustrates the temporal variation of a current flowing through an electrode of a radiation absorbing layer exposed to radiation (upper curve) and the corresponding temporal variation of a voltage of the electrode (lower curve) when an electronic system detects a higher rate of incident radiation particles according to an embodiment, wherein the current is caused by carriers generated by radiation particles incident on the radiation absorbing layer.

[0029] Figure 7 Schematically illustrating the Figure 6The temporal variation of the current flowing through an electrode (upper curve) and the corresponding temporal variation of the voltage of the electrode (lower curve) caused by noise (eg, dark current) in an electronic system operating in the manner shown.

[0030] Figure 8 Schematically illustrating the Figure 6 The time variation of the current flowing through the electrode (upper curve) and the corresponding time variation of the voltage of the electrode caused by the carriers generated by a series of radiation particles incident on the radiation absorbing layer in the electronic system operating in the manner shown, wherein the reset period RST is at time t e terminated before.

[0031] Fig.9A According to an embodiment, it is shown that it is suitable to use Figure 4 A flow chart of a method of operating an electronic system or the like to detect radiation is shown.

[0032] Fig. 9B According to an embodiment, it is shown that it is suitable to use Figure 6 A flow chart of a method of operating an electronic system or the like to detect radiation is shown.

[0033] Fig.10 A perspective view schematically illustrates an imaging system according to an embodiment.

[0034] Fig.11 is a flow chart summarizing the operation of the imaging system according to the embodiment. [Specific implementation method]

[0035] Radiation Detectors

[0036] Figure 1AA semiconductor radiation detector 100 according to an embodiment is schematically shown. The semiconductor radiation detector 100 may include a radiation absorption layer 110 and an electronic circuit layer 120 (e.g., an application-specific integrated circuit or ASIC) for processing or analyzing an electrical signal generated in the radiation absorption layer 110 by incident radiation. In one embodiment, the semiconductor radiation detector 100 does not include a scintillator. The radiation absorption layer 110 may include a semiconductor material, such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor may have a high mass attenuation coefficient for the radiation energy of interest. The radiation absorption layer 110 may include one or more diodes (e.g., pin or pn) formed by one or more discrete regions 114 of a first doping region 111 and a second doping region 113. The second doping region 113 may be separated from the first doping region 111 by an optional intrinsic region 112. The discrete regions 114 are separated from each other by the first doping region 111 or the intrinsic region 112. The first doping region 111 and the second doping region 113 have opposite doping types (for example, the first doping region 111 is p-type and the second doping region 113 is n-type, or the first doping region 111 is n-type and the second doping region 113 is p-type). Figure 1A In the example of , each discrete region 114 of the second doped region 113 forms a diode together with the first doped region 111 and the optional intrinsic region 112. That is, in Figure 1A In the example of FIG. 1 , the radiation absorbing layer 110 has a plurality of diodes having a first doping region 111 as a common electrode. The first doping region 111 may also have a plurality of discrete regions.

[0037] Figure 1B A semiconductor radiation detector 100 according to an alternative embodiment is shown. The semiconductor radiation detector 100 may include a radiation absorbing layer 110 and an electronic circuit layer 120 (e.g., an application specific integrated circuit) for processing or analyzing an electrical signal generated in the radiation absorbing layer 110 by incident radiation. In one embodiment, the semiconductor radiation detector 100 does not include a scintillator. The radiation absorbing layer 110 may include a semiconductor material, such as silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. The semiconductor may have a high mass attenuation coefficient for the radiation energy of interest. The radiation absorbing layer 110 may not include a diode, but may include a resistor.

[0038] When a radiation particle strikes the radiation absorption layer 110 including the diode, it can be absorbed and generate one or more carriers through a variety of mechanisms. The radiation particle can generate 10 to 100,000 carriers. The carriers can drift to the electrode of one of the diodes under the action of an electric field. The electric field can be an external electric field. The electrical contact (or electrode) 119B may include a plurality of discrete portions that are electrically in contact with a plurality of discrete regions 114, respectively. In one embodiment, the carriers can drift in multiple directions, and the carriers generated by a single radiation particle are substantially not shared by two different discrete regions 114 (here, "substantially not shared by..." means that the discrete region 114 to which less than 5%, less than 2%, or less than 1% of these carriers flow is different from the discrete region 114 to which the remaining carriers flow). In one embodiment, the carriers generated by a single radiation particle can be shared by two different discrete regions 114.

[0039] Figure 2 An exemplary top view of a portion of a semiconductor radiation detector 100 is shown, which has a 4×4 array of discrete regions 114. The carriers generated by radiation particles incident on one of the discrete regions 114 are substantially not shared by another discrete region 114 of the discrete regions 114. The area around a certain discrete region 114 is called a pixel (also called a sensing element) associated with the discrete region 114, in which substantially all (more than 95%, more than 98%, or more than 99%) of the carriers generated by radiation particles incident on the area flow to the discrete region 114. In other words, less than 5%, less than 2%, or less than 1% of the carriers flow out of the pixel. By measuring the drift current flowing into each discrete region 114 or the rate of change of the voltage of each discrete region 114, the number of radiation particles absorbed in the pixel associated with the discrete region 114 (which is related to the incident radiation intensity) and / or the energy of the radiation particles can be determined. Thus, the spatial distribution (e.g., image) of the incident radiation intensity can be determined by individually measuring the drift current flowing into each discrete region in the array of discrete regions 114 or measuring the rate of change of the voltage of each discrete region in the array of discrete regions 114. The pixels can be organized into any suitable array, such as a square array, a triangular array, and a honeycomb array. The pixels can have any suitable shape, such as a circle, a triangle, a square, a rectangle, and a hexagon. The pixels can be individually addressable.

[0040] When a radiation particle strikes the radiation absorption layer 110, which includes a resistor but does not include a diode, it can be absorbed and generate one or more carriers through a variety of mechanisms. The radiation particle can generate 10 to 100,000 carriers. The carriers can drift to the electrical contacts 119A and 119B under the action of the electric field. The electric field can be an external electric field. The electrical contact 119B includes a plurality of discrete portions. In one embodiment, the carriers can drift in multiple directions, and the carriers generated by a single radiation particle are substantially not shared by two different discrete portions of the electrical contact 119B (here "substantially not shared by..." means that the discrete portion to which less than 5%, less than 2%, or less than 1% of these carriers flow is different from the discrete portion to which the rest of these carriers flow). In one embodiment, the carriers generated by a single radiation particle can be shared by two different discrete portions of the electrical contact 119B. The carriers generated by radiation particles incident on the periphery of one of the discrete portions of the electrical contact 119B are substantially not shared by another of the discrete portions of the electrical contact 119B. The area around a discrete portion of the electrical contact 119B is referred to as a pixel associated with the discrete portion of the electrical contact 119B, in which substantially all (more than 95%, more than 98%, or more than 99%) of the carriers generated by radiation particles incident on the area flow toward the discrete portion of the electrical contact 119B. That is, less than 5%, less than 2%, or less than 1% of these carriers flow out of the pixel associated with the discrete portion of the electrical contact 119B. By measuring the drift current flowing into each discrete portion of the electrical contact 119B or the rate of change of the voltage of each discrete portion of the electrical contact 119B, the number of radiation particles absorbed in the pixel associated with the discrete portion of the electrical contact 119B (which is related to the intensity of the incident radiation) and / or the energy of the radiation particles can be determined. Thus, the spatial distribution (e.g., image) of incident radiation intensity can be determined by individually measuring the drift current flowing into each discrete portion of the array of discrete portions of electrical contacts 119B or measuring the rate of change of the voltage of each discrete portion of the array of discrete portions of electrical contacts 119B. The pixels can be organized into any suitable array, such as a square array, a triangular array, and a honeycomb array. The pixels can have any suitable shape, such as a circle, a triangle, a square, a rectangle, and a hexagon. The pixels can be individually addressable.

[0041] For each pixel, the electronic circuit layer 120 may include an electronic system 121 suitable for processing or interpreting signals generated by radiation particles incident on each pixel of the radiation absorption layer 110. The electronic system 121 may include analog circuits such as filter networks, amplifiers, integrators, and comparators, or digital circuits such as microprocessors and memories. The electronic system 121 may include components shared by multiple pixels or components dedicated to a single pixel. For example, the electronic system 121 may include an amplifier dedicated to each pixel and a microprocessor shared by all pixels. The electronic system 121 may be electrically connected to the pixel through a conductive portion 131. The space between the conductive portions may be filled with a filling material 130, which may increase the mechanical stability of the connection between the electronic circuit layer 120 and the radiation absorption layer 110. Other bonding techniques may connect the electronic system 121 to the pixel without using a conductive portion.

[0042] Electronic Systems

[0043] Figure 3A and Figure 3B Each of the diagrams shows a component of the electronic system 121 according to an embodiment. The electronic system 121 may include a first voltage comparator 301 , a second voltage comparator 302 , a counter 320 , a switch 305 , a voltmeter 306 , and a controller 310 .

[0044] The first voltage comparator 301 is configured to connect an electrode (eg, Figure 1A or Figure 1B119B) is compared with a first threshold value. The diode can be a diode formed by a first doped region 111, a discrete region 114 of a plurality of discrete regions 114 of a second doped region 113, and an optional intrinsic region 112. Alternatively, the first voltage comparator 301 is configured to compare the voltage of an electrical contact (e.g., a discrete portion of the electrical contact 119B) with a first threshold value. The first voltage comparator 301 can be configured to monitor the voltage directly, or to calculate the voltage by integrating the current flowing through the diode or the electrical contact over a period of time. The controller 310 can controllably enable or disable the first voltage comparator 301. The first voltage comparator 301 can be a continuous comparator. That is, the first voltage comparator 301 can be configured to be enabled continuously and to monitor the voltage continuously. The first voltage comparator 301 configured as a continuous comparator reduces the probability that the system 121 misses a signal generated by an incident radiation particle. The first voltage comparator 301 configured as a continuous comparator is particularly applicable when the incident radiation intensity is relatively high. The first voltage comparator 301 may be a clocked comparator, which has the advantage of low power consumption. The first voltage comparator 301 configured as a clocked comparator may cause the system 121 to miss signals generated by some incident radiation particles. When the incident radiation intensity is low, the probability of missing the incident radiation particles is low because the time interval between two consecutive photons is relatively long. Therefore, the first voltage comparator 301 configured as a clocked comparator is particularly applicable when the incident radiation intensity is relatively low. The first threshold value may be 5-10%, 10%-20%, 20-30%, 30-40% or 40-50% of the maximum voltage that an incident radiation particle can generate in a diode or resistor. The maximum voltage may depend on the energy of the incident radiation particle (i.e., the wavelength of the incident radiation particle), the material of the radiation absorbing layer 110, and other factors. For example, the first threshold value may be 50mV, 100mV, 150mV or 200mV.

[0045] The second voltage comparator 302 is configured to compare the voltage with the second threshold value. The second voltage comparator 302 can be configured to directly monitor the voltage, or to calculate the voltage by integrating the current flowing through the diode or the electrical contact over a period of time. The second voltage comparator 302 can be a continuous comparator. The controller 310 can controllably enable or disable the second voltage comparator 302. When the second voltage comparator 302 is disabled, the power consumption of the second voltage comparator 302 can be 1%, 5%, 10% or 20% less than the power consumption when the second voltage comparator 302 is enabled. The absolute value of the second threshold value is greater than the absolute value of the first threshold value. As used herein, the term "absolute value" or "modulus" |x| of a real number x is a non-negative value of x regardless of its sign. That is, if x>=0, then |x|=x, and, if x<0, then |x|=-x.

[0046] The second threshold value can be 200%-300% of the first threshold value. The second threshold value can be at least 50% of the maximum voltage that an incident radiation particle can generate in a diode or a resistor. For example, the second threshold value can be 100mV, 150mV, 200mV, 250mV or 300mV. The second voltage comparator 302 and the first voltage comparator 301 can be the same component. In other words, the system 121 can have a voltage comparator that can compare voltage with two different threshold values ​​at different times.

[0047] The first voltage comparator 301 or the second voltage comparator 302 may include one or more operational amplifiers or any other suitable circuits. The first voltage comparator 301 or the second voltage comparator 302 may have a high speed to allow the system 121 to operate under high incident radiation flux. However, high speed often comes at the expense of power consumption.

[0048] The counter 320 is configured to record the number of radiation particles reaching the diode or resistor. The counter 320 can be a software component (eg, a number stored in a computer memory) or a hardware component (eg, 4017 IC and 7490 IC).

[0049] The controller 310 can be a hardware component, such as a microcontroller and a microprocessor. The controller 310 is configured to start the time delay from the time when the first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold (for example, the absolute value of the voltage increases from an absolute value below the first threshold to a value equal to or higher than the absolute value of the first threshold). Absolute values ​​are used herein because the voltage can be negative or positive, depending on whether the voltage of the cathode or anode of the diode is used or which electrical contact is used. The controller 310 can be configured to keep the second voltage comparator 302, the counter 320, and any other circuits not required for the operation of the first voltage comparator 301 disabled before the first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold. The time delay can be terminated before or after the voltage becomes stable, that is, the rate of change of the voltage is substantially zero. The phrase "the rate of change of the voltage is substantially zero" means that the time change of the voltage is less than 0.1% / ns. The phrase "the rate of change of the voltage is substantially not zero" means that the time change of the voltage is at least 0.1% / ns.

[0050] The controller 310 may be configured to enable the second voltage comparator during the time delay (including the start and end). In one embodiment, the controller 310 is configured to enable the second voltage comparator at the start of the time delay. The term "enable" means that the component enters an operating state (e.g., by sending a signal such as a voltage pulse or a logic level, by providing power, etc.). The term "disable" means that the component enters a non-operating state (e.g., by sending a signal such as a voltage pulse or a logic level, by cutting off power, etc.). The operating state may have a higher power consumption (e.g., 10 times higher, 100 times higher, 1000 times higher) than the non-operating state. When the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value, the controller 310 itself may be disabled until the output of the first voltage comparator 301 enables the controller 310.

[0051] The controller 310 may be configured to increase the number recorded by the counter 320 by one if the second voltage comparator 302 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold during the time delay.

[0052] The controller 310 can be configured to cause the voltmeter 306 to measure the voltage when the time delay expires. The controller 310 can be configured to connect the electrode to electrical ground to reset the voltage and release any carriers accumulated on the electrode. In one embodiment, after the time delay expires, the electrode is connected to electrical ground. In one embodiment, the electrode is connected to electrical ground for a limited reset period. The controller 310 can connect the electrode to electrical ground by controlling the switch 305. The switch can be a transistor, such as a field effect transistor (FET).

[0053] In one embodiment, system 121 has no analog filtering networks (eg, RC networks). In one embodiment, system 121 has no analog circuits.

[0054] The voltmeter 306 may feed its measured voltage to the controller 310 as an analog signal or a digital signal.

[0055] The system 121 may include a capacitance module 309 electrically connected to the electrodes or electrical contacts of the diode 300. The capacitance module is configured to collect carriers from the electrodes. The capacitance module can include a capacitor located in the feedback path of the amplifier. An amplifier configured in this way is called a capacitive transimpedance amplifier (CTIA). A capacitive transimpedance amplifier has a high dynamic range by preventing the amplifier from saturating and improves the signal-to-noise ratio by limiting the bandwidth in the signal path. The carriers from the electrodes are collected for a period of time ("integration period", e.g., Figure 4 As shown, at t 0 to 1 Between, or t 1 -t 2 After the integration period ends, the voltage of the capacitor is sampled and then reset by the reset switch. The capacitance module can include a capacitor directly connected to the electrode.

[0056] Electrode current and voltage

[0057] Figure 4 Schematically shows the time variation of the current flowing through the electrode caused by the carriers generated by the radiation particles incident on the diode or resistor (upper curve) and the corresponding time variation of the voltage of the electrode (lower curve). The voltage can be the integral of the current with respect to time. At time t 0 , the radiation particle hits the diode or resistor, carriers begin to be generated in the diode or resistor, current begins to flow through the electrode of the diode or the electrical contact of the resistor, and the absolute value of the voltage of the electrode or electrical contact begins to increase. At time t 1 , the first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value V1, and the controller 310 starts the time delay TD1, and the controller 310 can deactivate the first voltage comparator 301 when the time delay TD1 starts. 1 If it was previously disabled, then at t 1The controller 310 is enabled. During the time delay TD1, the controller 310 enables the second voltage comparator 302. As used herein, the term "period" of a time delay refers to the beginning and the end (i.e., the end) and any time therebetween. For example, the controller 310 may enable the second voltage comparator 302 when the time delay TD1 ends. If during the time delay TD1, the second voltage comparator 302 is enabled at time t 2 If the absolute value of the voltage is determined to be equal to or greater than the absolute value of the second threshold value V2, the controller 310 increases the number recorded by the counter 320 by one. e , all carriers generated by the radiation particles drift out of the radiation absorption layer 110. At time t s , time delay TD1 is terminated. Figure 4 In the example, time t s At time t e That is, the time delay TD1 ends after all carriers generated by the radiation particles drift out of the radiation absorption layer 110. Therefore, the rate of change of the voltage is t s is substantially zero. The controller 310 may be configured to 2 , or disable the second voltage comparator 302 at any time in between.

[0058] The controller 310 may be configured to cause the voltmeter 306 to measure the voltage when the time delay TD1 expires. In one embodiment, the controller 310 causes the voltmeter 306 to measure the voltage after the rate of change of the voltage becomes substantially zero after the time delay TD1 expires. The voltage at this time is proportional to the number of carriers generated by the radiation particles, which is related to the energy of the radiation particles. The controller 310 may be configured to determine the energy of the radiation particles based on the voltage measured by the voltmeter 306. One way to determine the energy is to bin the voltage. The counter 320 may have a sub-counter for each bin. When the controller 310 determines that the energy of the radiation particle falls in a bin, the controller 310 may cause the number recorded in the sub-counter for the bin to increase by one. Therefore, the system 121 is capable of detecting radiation images and is capable of resolving the radiation energy of each radiation particle.

[0059] After the time delay TD1 expires, the controller 310 connects the electrode to electrical ground during a reset period RST to allow carriers accumulated at the electrode to flow to ground and reset the voltage. After the reset period RST, the system 121 is ready to detect another incident radiation particle. Potentially, Figure 4In the example of , the rate of incident radiation particles that the system 121 can handle is limited to 1 / (TD1+RST). If the first voltage comparator 301 has been disabled, the controller 310 can enable the first voltage comparator 301 at any time before the reset period RST ends. If the controller 310 has been disabled, the controller 310 can be enabled before the reset period RST ends.

[0060] Figure 5 Schematically showing the Figure 4 In the system 121 operating in the manner shown, the temporal variation of the current flowing through the electrode (upper curve) and the corresponding temporal variation of the voltage of the electrode (lower curve) caused by noise (e.g., dark current, background radiation, scattered X-rays, fluorescent X-rays, shared charges from adjacent pixels) are shown. 0 , the noise starts. If the noise is not large enough to cause the absolute value of the voltage to exceed the absolute value of the first threshold V1, the controller 310 does not enable the second voltage comparator 302. If the first voltage comparator 301 determines that the noise is large enough to cause the absolute value of the voltage to exceed the absolute value of the first threshold V1 at time t 1 If the absolute value of the voltage exceeds the absolute value of V1, the controller 310 starts the time delay TD1, and the controller 310 may disable the first voltage comparator 301 at the beginning of the time delay TD1. During the time delay TD1 (for example, when TD1 ends), the controller 310 enables the second voltage comparator 302. The noise is unlikely to be large enough to cause the absolute value of the voltage to exceed the absolute value of the second threshold V2 during the time delay TD1. Therefore, the controller 310 does not increase the number recorded by the counter 320. At time t e , the noise ends. At time t s , the time delay TD1 is terminated. The controller 310 can be configured to deactivate the second voltage comparator 302 when the time delay TD1 is terminated. The controller 310 can be configured to not cause the voltmeter 306 to measure the voltage if the absolute value of the voltage does not exceed the absolute value of the second threshold value V2 during the time delay TD1. After the time delay TD1 is terminated, the controller 310 connects the electrode to the electrical ground during the reset period RST to allow carriers accumulated at the electrode due to noise to flow to the ground and reset the voltage. Therefore, the system 121 can be very effective in noise suppression.

[0061] Figure 6 Schematically shows the time variation of the current flowing through the electrode (upper curve) and the corresponding time variation of the voltage of the electrode (lower curve) caused by the carriers generated by the radiation particles incident on the diode or resistor when the system 121 detects incident radiation particles at a rate higher than 1 / (TD1+RST). The voltage can be the integral of the current with respect to time. At time t 0, the radiation particle hits the diode or resistor, carriers begin to be generated in the diode or resistor, current begins to flow through the electrode of the diode or the electrical contact of the resistor, and the absolute value of the voltage at the electrode or electrical contact begins to increase. At time t 1 , the first voltage comparator 301 determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value V1, the controller 310 starts a time delay TD2 that is shorter than the time delay TD1, and the controller 310 can deactivate the first voltage comparator 301 at the beginning of the time delay TD2. 1 was deactivated before, then at time t 1 The controller 310 is enabled. During the time delay TD2 (eg, when the time delay TD2 expires), the controller 310 enables the second voltage comparator 302. If during the time delay TD2, the second voltage comparator 302 determines that the absolute value of the voltage is greater than or equal to the absolute value of the voltage at time t 2 If the absolute value of the second threshold value V2 is equal to or exceeds the absolute value of the second threshold value V2, the controller 310 increases the number recorded by the counter 320 by one. e , all carriers generated by the radiation particles drift out of the radiation absorption layer 110. At time t h , time delay TD2 is terminated. Figure 6 In the example, time t h At time t e That is, the time delay TD2 ends before all carriers generated by the radiation particles drift out of the radiation absorbing layer 110. Therefore, the rate of change of the voltage at time t h is substantially non-zero. The controller 310 may be configured to, at the expiration of the time delay TD2, or at the time t 2 , or disable the second voltage comparator 302 at any time in between.

[0062] The controller 310 may be configured to infer the time t from the voltage as a function of time during the time delay TD2. e The voltage at which a particle is emitted is determined using the inferred voltage.

[0063] After the time delay TD2 expires, the controller 310 connects the electrode to electrical ground during a reset period RST to allow carriers accumulated at the electrode to flow to the ground and reset the voltage. In one embodiment, the reset period RST is at time t e The rate of change of the voltage after the reset period RST may not be substantially zero because when the reset period RST is at time t e At the time of termination, all carriers generated by the radiation particles have not yet drifted out of the radiation absorption layer 110. The rate of change of voltage at time t e After that, it becomes basically zero, and the voltage at time te Then it stabilizes to the residual voltage VR. In one embodiment, the reset period RST is at time t e Time or time t e After that, the voltage change rate after the reset period RST can be substantially zero because at time t e All carriers generated by the radiation particles drift out of the radiation absorbing layer 110. After the reset period RST, the system 121 is ready to detect another incident radiation particle. If the first voltage comparator 301 has been disabled, the controller 310 can enable the first voltage comparator 301 at any time before the reset period RST ends. If the controller 310 has been disabled, the controller 310 can be enabled before the reset period RST ends.

[0064] Figure 7 Schematically showing the Figure 6 In the system 121 operating in the manner shown, the temporal variation of the current flowing through the electrode (upper curve) and the corresponding temporal variation of the voltage of the electrode (lower curve) caused by noise (e.g., dark current, background radiation, scattered radiation, fluorescent X-rays, shared charge from adjacent pixels) are shown. 0 , the noise starts. If the noise is not large enough to cause the absolute value of the voltage to exceed the absolute value of the first threshold V1, the controller 310 does not enable the second voltage comparator 302. If the first voltage comparator 301 determines that the noise is large enough to cause the absolute value of the voltage to exceed the absolute value of the first threshold V1 at time t 1 If the absolute value of the voltage exceeds the first threshold V1, the controller 310 starts the time delay TD2, and the controller 310 may disable the first voltage comparator 301 at the beginning of the time delay TD2. During the time delay TD2 (e.g., when the time delay TD2 ends), the controller 310 enables the second voltage comparator 302. The noise is unlikely to be large enough to cause the absolute value of the voltage to exceed the absolute value of the second threshold V2 during the time delay TD2. Therefore, the controller 310 does not increase the number recorded by the counter 320. At time t e , the noise ends. At time t h , the time delay TD2 is terminated. The controller 310 can be configured to deactivate the second voltage comparator 302 when the time delay TD2 is terminated. After the time delay TD2 is terminated, the controller 310 connects the electrode to the electrical ground during the reset period RST to allow carriers accumulated at the electrode due to noise to flow to the ground and reset the voltage. Therefore, the system 121 can be very effective in noise suppression.

[0065] Figure 8 Schematically showing the Figure 6In the system 121 operating in the manner shown, the time variation of the current flowing through the electrode (upper curve) and the corresponding time variation of the voltage of the electrode (lower curve) caused by the carriers generated by a series of radiation particles incident on the diode or resistor, wherein the reset period RST is at time t e The voltage curve caused by the carriers generated by each incident radiation particle is offset by the residual voltage before the photon. The absolute value of the residual voltage increases continuously with each incident photon. When the absolute value of the residual voltage exceeds the first threshold value V1 (see Figure 8 ), the controller starts the time delay TD2, and the controller 310 can deactivate the first voltage comparator 301 at the beginning of the time delay TD2. If no other radiation particles are incident on the diode or resistor during the time delay TD2, when the time delay TD2 ends, the controller connects the electrode to the electrical ground during the reset period RST, thereby resetting the residual voltage. Therefore, the residual voltage does not increase the number recorded by the counter 320.

[0066] Run the flow chart

[0067] Fig.9A Shows that it is suitable to use such as Figure 41. A flow chart of a method for detecting radiation using a system such as the system 121 operating as shown in FIG. 1. In step 901, the voltage of an electrode of a diode or an electrical contact of a resistor exposed to radiation is compared with a first threshold value, for example, using a first voltage comparator 301. In step 902, it is determined whether the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value V1, for example, using a controller 310. If the absolute value of the voltage is not equal to or does not exceed the absolute value of the first threshold value, the method returns to step 901. If the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value, then continue to step 903. In step 903, for example, using a controller 310, a time delay TD1 is started. In step 904, for example, using a controller 310, a circuit (e.g., a second voltage comparator 302 or a counter 320) is enabled during the time delay TD1 (e.g., when the time delay TD1 expires). In step 905, for example, using a second voltage comparator 302, the voltage is compared with a second threshold value V2. In step 906, it is determined, for example using the controller 310, whether the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold value V2. If the absolute value of the voltage is not equal to or does not exceed the absolute value of the second threshold value, the method proceeds to step 910. If the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold value, then continue to step 907. In step 907, for example using the controller 310, the number recorded in the counter 320 is increased by one. In optional step 908, for example using the voltmeter 306, the voltage at the end of the time delay TD1 is measured. In optional step 909, for example using the controller 310, the radiation particle energy is determined based on the voltage measured in step 908. There may be a counter for each energy bin. After measuring the radiation particle energy, the counter for the bin to which the photon energy belongs can be increased by one. The method proceeds to step 910 after step 909. In step 910, the voltage is reset to electrical ground, for example by connecting an electrode of a diode or an electrical contact of a resistor to electrical ground. For example, when neighboring pixels share a large portion (eg, >30%) of carriers generated from a single photon, steps 908 and 909 may be omitted.

[0068] Fig. 9B Shows that it is suitable to use such as Figure 61. A flow chart of a method for detecting radiation using a system such as the system 121 operating as shown in FIG. 1. In step 901B, the voltage of the electrode of the diode or the electrical contact of the resistor exposed to the radiation is compared with the first threshold value, for example using the first voltage comparator 301. In step 902B, it is determined whether the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value V1, for example using the controller 310. If the absolute value of the voltage is not equal to or does not exceed the absolute value of the first threshold value, the method returns to step 901B. If the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold value, then continue to step 903B. In step 903B, for example using the controller 310, start the time delay TD2. In step 904B, for example using the controller 310, enable the circuit (e.g., the second voltage comparator 302 or the counter 320) during the time delay TD2 (e.g., when the time delay TD2 expires). In step 905B, for example using the second voltage comparator 302, the voltage is compared with the second threshold value. In step 906B, it is determined, for example, using the controller 310, whether the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold value V2. If the absolute value of the voltage is not equal to or does not exceed the absolute value of the second threshold value, the method proceeds to step 910B. If the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold value, then continue to step 907B. In step 907B, for example, using the controller 310, the number recorded in the counter 320 is increased by one. The method proceeds to step 910B after step 907B. In step 910B, the voltage is reset to electrical ground, for example, by connecting an electrode of a diode or an electrical contact of a resistor to electrical ground.

[0069] The semiconductor radiation detector 100 can be used for phase contrast X-ray imaging (PCI) (also known as phase sensitive X-ray imaging). Phase contrast X-ray imaging includes techniques that use at least in part the phase shift of an X-ray beam caused by an object (including the spatial distribution of the phase shift) to form an image of the object. One method of obtaining the phase shift is to convert the phase into an intensity change.

[0070] Phase contrast X-ray imaging can be combined with tomography to obtain a 3D distribution of the real part of the refractive index of an object. Compared to conventional intensity-based X-ray imaging (e.g., radiography), phase contrast X-ray imaging is more sensitive to density variations in an object. Phase contrast X-ray imaging is particularly suitable for imaging soft tissues.

[0071] Imaging System

[0072] Fig.10 A perspective view of an imaging system 1000 according to an embodiment is schematically shown. In one embodiment, the imaging system 1000 may include a radiation source 1010 and an image sensor 1020.

[0073] In one embodiment, radiation source 1010 may send radiation beam 1012 toward an object (eg, a pet). In one embodiment, image sensor 1020 may capture an image of the object based on the interaction between radiation beam 1012 and the object.

[0074] The interaction between the radiation beam 1012 and the object may include situations where some radiation particles of the radiation beam 1012 incident on the object are blocked by the object and where some radiation particles of the radiation beam 1012 incident on the object pass through the object without changing their direction.

[0075] In one embodiment, image sensor 1020 may include one or more (e.g., 8, as shown) semiconductor radiation detectors 100 and one or more (e.g., 2, as shown) input / output regions 1025. In one embodiment, input / output region 1025 may be a region of image sensor 1020 having contact pads (not shown) thereon for electrically interconnecting transmission lines from an application specific integrated circuit of electronic circuit layer 120 of semiconductor radiation detector 100 of image sensor 1020 and transmission lines leading to circuits external to image sensor 1020.

[0076] In one embodiment, input / output region 1025 may be located at an edge of image sensor 1020 (as shown).

[0077] In one embodiment, the radiation receiving surface of the image sensor 1020 may define a reference plane 1029 parallel to the radiation receiving surface. In one embodiment, a straight line segment connecting two orthogonal projections of any two sensing elements of the eight semiconductor radiation detectors 100 of the image sensor 1020 on the reference plane 1029 does not intersect with an orthogonal projection of any input / output region 1025 for the eight semiconductor radiation detectors 100 on the reference plane 1029.

[0078] In one embodiment, any straight line that intersects the radiation source 1010 and any sensing element of the eight semiconductor radiation detectors 100 does not intersect any portion of any input / output region 1025 for any of the eight semiconductor radiation detectors 100. Thus, the input / output region 1025 of the image sensor 1020 does not obstruct the radiation beam 1012 traveling from the radiation source 1010 to the eight semiconductor radiation detectors 100.

[0079] Cannula for restraining pets for imaging

[0080] In one embodiment, referring to Fig.10 , the imaging system 1000 may include a cannula (not shown) for restraining a pet (eg, a cat) 1090 for imaging.

[0081] In one embodiment, the cannula can secure the pet 1090 so that the pet 1090 remains stationary relative to the image sensor 1020 used for imaging the bladder or kidneys 1092 of the pet 1090, and so that any straight lines intersecting the bladder / kidneys 1092 of the pet 1090, the radiation source 1010, and the image sensor 1020 do not intersect any bones of the pet 1090.

[0082] In one embodiment, image sensor 1020 may be mounted on the wall of the cannula.

[0083] In one embodiment, a sleeve may be located between radiation source 1010 and image sensor 1020 .

[0084] Harness to restrain pets for imaging

[0085] In one embodiment, referring to Fig.10 , the imaging system 1000 may include a strap (not shown) for restraining a pet (eg, a cat) 1090 for imaging.

[0086] In one embodiment, the strap of imaging system 1000 may be similar to the strap of a blood pressure monitor.

[0087] In one embodiment, a strap of the imaging system 1000 may be wrapped around the abdominal area of ​​the pet 1090 such that the pet 1090 remains stationary relative to the image sensor 1020 for imaging the bladder / kidneys 1092 of the pet 1090 and such that any straight lines intersecting the bladder / kidneys 1092 of the pet 1090, the radiation source 1010, and the image sensor 1020 do not intersect any bones of the pet 1090.

[0088] In one embodiment, image sensor 1020 may be mounted on a strap.

[0089] In one embodiment, a strap may be located between radiation source 1010 and image sensor 1020 .

[0090] Operation of the imaging system

[0091] In one embodiment, referring to Fig.10 , the operation of the imaging system 1000 may be as follows. A radiation source 1010 may send a radiation beam 1012 toward a bladder / kidney 1092 of a pet 1090 secured by a cannula or strap. In one embodiment, the radiation beam 1012 may be an X-ray beam having a photon energy of less than 10 KeV.

[0092] In one embodiment, the image sensor 1020 can take an image of the bladder / kidney 1092 based on the interaction between the radiation beam 1012 and the bladder / kidney 1092. In one embodiment, the image of the bladder / kidney 1092 can be examined to detect stones in the bladder / kidney 1092 of the pet 1090.

[0093] In one embodiment, the value of each pixel of the image of the bladder / kidney 1092 may be compared to a counter 320 ( Figure 3A and Figure 3B ) is related to the number recorded.

[0094] In one embodiment, any straight line that intersects the bladder / kidney 1092 , the radiation source 1010 , and the image sensor 1020 does not intersect any bones of the pet 1090 .

[0095] Flowchart outlining the operation of the imaging system

[0096] Fig.11 Shows a summary according to an embodiment Fig.10 Flowchart 1100 of the operation of the imaging system 1000.

[0097] In step 1110, the operation may include using a radiation source to generate a radiation beam directed toward the kidney or bladder of the pet secured by the cannula or strap. For example, in the above embodiment, reference is made to Fig.10 , a radiation source 1010 sends a radiation beam 1012 toward the bladder / kidneys 1092 of a pet 1090 which is secured by a sleeve or strap.

[0098] In step 1120, the operation may include using an image sensor to capture an image of the kidney or bladder based on the interaction between the radiation beam and the kidney or bladder during exposure. Fig.10 The image sensor 1020 captures an image of the bladder / kidney 1092 based on the interaction between the radiation beam 1012 and the bladder / kidney 1092 .

[0099] Although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes and are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

Claims

1. An imaging system, characterized in that: include: a radiation source configured to send a radiation beam toward the pet; an image sensor configured to capture an image of the pet based on an interaction between the radiation beam and the pet; as well as Sleeve or strap, wherein the sleeve or the strap is configured to fix the pet so that the pet remains stationary relative to the image sensor for imaging and any straight line intersecting the pet's kidney or bladder, the image sensor, and the radiation source does not intersect any bone of the pet, wherein the image sensor is mounted on the wall of the sleeve or on the strap, and the sleeve or the strap is located between the image sensor and the radiation source, The image sensor comprises: M radiation detectors, M is a positive integer; and N input / output areas for the M radiation detectors, N is a positive integer, wherein the N input / output areas are located at the edge of the image sensor; Wherein, each of the M radiation detectors comprises: a radiation absorbing layer, including electrodes; a first voltage comparator configured to compare the voltage of the electrode with a first threshold; a second voltage comparator configured to compare the voltage with a second threshold; a counter configured to record the number of photons absorbed by the radiation absorbing layer; and Controller, wherein the controller is configured to initiate the time delay from the time when the first voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the first threshold; wherein the controller is configured to enable the second voltage comparator during the time delay, and The controller is configured to increase the number recorded by the counter by one if the second voltage comparator determines that the absolute value of the voltage is equal to or exceeds the absolute value of the second threshold.

2. The imaging system according to claim 1, characterized in that The reference plane is parallel to the radiation receiving surface of the image sensor, A straight line segment respectively connecting two orthogonal projections of any two sensing elements of the M radiation detectors on the reference plane does not intersect an orthogonal projection of any input / output region of the M radiation detectors on the reference plane.

3. The imaging system according to claim 1, characterized in that Any straight line that intersects the radiation source and any sensing element of the M radiation detectors does not intersect any portion of any input / output region for any of the M radiation detectors.

4. The imaging system according to claim 1, characterized in that The radiation beam is an X-ray beam with a photon energy less than 10 KeV.

5. The imaging system according to claim 1, characterized in that Each of the radiation detectors further includes a capacitive module electrically connected to the electrode, The capacitor module is configured to collect carriers from the electrode.

6. The imaging system according to claim 1, characterized in that: The controller is configured to enable the second voltage comparator when the time delay begins or ends.

7. The imaging system according to claim 1, characterized in that: Each radiation detector further comprises a voltmeter, The controller is configured to cause the voltmeter to measure the voltage when the time delay expires.

8. The imaging system according to claim 7, characterized in that: The controller is configured to determine a photon energy based on a value of the voltage measured at the expiration of the time delay.

9. The imaging system according to claim 1, characterized in that: The controller is configured to electrically connect the electrode to an electrical ground.

10. The imaging system according to claim 1, characterized in that At the end of the time delay, the rate of change of the voltage is substantially zero.

11. The imaging system according to claim 1, characterized in that: At the expiration of the time delay, the rate of change of the voltage is substantially non-zero.

12. The imaging system according to claim 1, characterized in that The radiation absorbing layer includes a diode.

13. The imaging system according to claim 1, characterized in that The radiation absorbing layer includes silicon, germanium, GaAs, CdTe, CdZnTe or a combination thereof.

14. The imaging system according to claim 1, characterized in that The system does not include a scintillator.

15. The imaging system according to claim 1, characterized in that The radiation absorbing layer includes an array of sensing elements.

16. The imaging system according to claim 1, characterized in that The strap is configured to wrap around the abdominal area of ​​the pet.

17. A method for operating an imaging system according to any one of claims 1 to 16, characterized in that: The method includes: Using the radiation source, generating a radiation beam directed toward a kidney or bladder of a pet secured by the sleeve or the strap; and Using the image sensor, an image of the kidney or the bladder is captured based on the interaction between the radiation beam and the kidney or the bladder during exposure.

18. The operating method according to claim 17, characterized in that: The value of a pixel of the image is related to the number registered by the counter of one of the M radiation detectors of the image sensor after exposure.

19. The operating method according to claim 17, characterized in that: Any straight line that intersects the kidney or the bladder, the image sensor, and the radiation source does not intersect any bone of the pet.

Images