阅读说明：本技术 一种辐射检测装置 (Radiation detection device ) 是由 曹培炎 刘雨润 于 2018-09-07 设计创作，主要内容包括：本文公开一种装置,其包括：平台(530),其配置成在所述平台(530)的第一表面(531)上支撑人体；第一组辐射检测器(521),其布置在第一层(510)中,其中所述第一组辐射检测器(521)连接到所述平台(530)中与所述第一表面(531)相对的第二表面(532)；其中所述第一组辐射检测器(521)配置成检测来自人体内辐射源的辐射。(Disclosed herein is an apparatus, comprising: a platform (530) configured to support a human body on a first surface (531) of the platform (530); a first set of radiation detectors (521) arranged in a first layer (510), wherein the first set of radiation detectors (521) are connected to a second surface (532) of the platform (530) opposite the first surface (531); wherein the first set of radiation detectors (521) is configured to detect radiation from a radiation source within a human body.)

1. An apparatus, comprising:

a platform configured to support a human body on a first surface of the platform;

a first set of radiation detectors disposed in a first layer, wherein the first set of radiation detectors is connected to a second surface of the platform opposite the first surface;

wherein the first set of radiation detectors is configured to detect radiation from a radiation source within the human body.

2. The apparatus of claim 1, wherein each radiation detector of the first set of radiation detectors is configured to detect an image of the radiation.

3. The apparatus of claim 1, wherein the first set of radiation detectors comprises two radiation detectors, an area of the first layer between the two radiation detectors being free of any radiation detectors.

4. The device of claim 1, wherein the radiation is beta or gamma radiation.

5. The apparatus of claim 1, wherein at least one radiation detector of the first set of radiation detectors comprises a first radiation absorbing layer configured to absorb the radiation and generate an electrical signal from the radiation.

6. The apparatus of claim 5, wherein the first radiation absorbing layer comprises silicon or GaAs.

7. The apparatus of claim 1, further comprising a second set of radiation detectors disposed in a second layer;

wherein the second set of radiation detectors is further from the second surface of the platform than the first set of radiation detectors;

wherein the second set of radiation detectors is configured to detect radiation from the radiation source.

8. The apparatus of claim 7, wherein each radiation detector of the second set of radiation detectors is spaced apart from the second surface of the platform by a same distance.

9. The apparatus of claim 7, wherein each radiation detector of the second set of radiation detectors is configured to detect an image of the radiation.

10. The apparatus of claim 7, wherein the second set of radiation detectors comprises two radiation detectors, an area of the second layer between the two radiation detectors being free of any radiation detectors.

11. The apparatus of claim 7, wherein the second set of radiation detectors comprises a second radiation absorbing layer configured to absorb the radiation and generate electrical signals from the radiation.

12. The apparatus of claim 11, wherein the second radiation absorbing layer comprises silicon or GaAs.

13. The apparatus of claim 1, further comprising a processor configured to determine a spatial distribution of the radiation source in the human body based on the radiation detected by the first set of radiation detectors.

14. The apparatus of claim 5, wherein the first radiation absorbing layer comprises an electrical contact.

15. The apparatus of claim 14, wherein the at least one radiation detector comprises:

a first voltage comparator configured to compare a voltage of the electrical contact with a first threshold;

a second voltage comparator configured to compare the voltage to a second threshold;

a counter configured to record the number of radiation particles incident on a pixel of the at least one radiation detector;

a controller;

wherein the controller is configured to initiate a time delay when the absolute value of the voltage is determined from the first voltage comparator to be equal to or exceed the absolute value of the first threshold;

wherein the controller is configured to activate the second voltage comparator during the time delay;

wherein the controller is configured to increase the number by one when the second voltage comparator determines that the absolute value of the voltage equals or exceeds the absolute value of the second threshold.

16. A method, comprising:

detecting radiation from a radiation source within the human body using a first set of radiation detectors arranged in a first layer;

detecting radiation from the radiation source using a second set of radiation detectors disposed in a second layer;

determining a spatial distribution of the radiation source based on the radiation detected by the first set of radiation detectors and the radiation detected by the second set of radiation detectors;

wherein the first layer and the second layer are at different distances from the human body.

17. The method of claim 16, wherein detecting the radiation from the radiation source using the first set of radiation detectors comprises detecting an image of the radiation.

18. The method of claim 16, wherein the first set of radiation detectors comprises two radiation detectors, an area of the first layer between the two radiation detectors being free of any radiation detectors.

19. The method of claim 16, wherein the first set of radiation detectors comprises a first radiation absorbing layer configured to absorb the radiation and generate electrical signals from the radiation.

20. The method of claim 19, wherein the first radiation absorbing layer comprises silicon or GaAs.

21. The method of claim 16, wherein detecting radiation from the radiation source using the second set of radiation detectors comprises detecting an image of the radiation.

22. The method of claim 16, wherein each radiation detector of the second set of radiation detectors is spaced apart from the first layer by the same distance.

23. The method of claim 16, wherein the second set of radiation detectors comprises two radiation detectors, the area of the second layer between the two radiation detectors being free of any radiation detectors.

24. The method of claim 16, wherein the second set of radiation detectors comprises a radiation absorbing layer configured to absorb the radiation and generate electrical signals from the radiation.

25. The method of claim 24, wherein the radiation absorbing layer comprises silicon or GaAs.

26. The method of claim 16, wherein the radiation is beta or gamma radiation.

[ technical field ] A method for producing a semiconductor device

The disclosure herein relates to a radiation detection apparatus.

[ background of the invention ]

A radiation detector is a device that can be used to measure the flux, spatial distribution, spectrum, or other properties of radiation. Radiation detectors are useful in many applications, one important application being imaging. Radiography is a radiographic technique that can be used to reveal the internal structure of objects of non-uniform composition and opacity (e.g., the human body).

Early radiation detectors used for imaging included photographic plates and photographic film. The photographic plate may be a glass plate with a photosensitive emulsion coating. Although photographic plates are replaced by photographic film, they can still be used in special situations due to the superior quality and extreme stability they provide. The photographic film may be a plastic film (e.g., strip or sheet) having a photosensitive emulsion coating.

In the 80's of the 20 th century, photostimulable phosphor plates (PSP plates) began to become available. The PSP board contains a phosphor material having a color center in its crystal lattice. When the PSP plate is exposed to radiation, electrons excited by the radiation are trapped in the color center until they are stimulated by a laser beam scanned over the surface of the PSP plate. When the laser scans the PSP plate, the captured excited electrons emit light, which is collected by a photomultiplier tube, and the collected light is converted into a digital image. Compared with photographic plates and films, the PSP plate is reusable.

Another type of radiation detector is a radiation image intensifier. The components of the radiation image intensifier are typically sealed in a vacuum. In contrast to photographic plates, photographic film and PSP plates, radiation image intensifiers can produce real-time images, i.e., do not require post-exposure processing to produce an image. The radiation first strikes the input phosphor (e.g., cesium iodide) and is converted to visible light. The visible light then strikes the photocathode (e.g., a thin metal layer containing cesium and antimony compounds) and causes electron emission. The number of emitted electrons is proportional to the intensity of the incident radiation. The emitted electrons are projected through electron optics onto the output phosphor and cause the output phosphor to produce a visible light image.

The scintillator operates somewhat similarly to a radiation image intensifier in that the scintillator (e.g., sodium iodide) absorbs radiation and emits visible light, which can then be detected by a suitable image sensor. In the scintillator, visible light is diffused and scattered in all directions, thereby reducing spatial resolution. Reducing the scintillator thickness helps to improve spatial resolution, but also reduces absorption of radiation. Therefore, the scintillator must achieve a compromise between absorption efficiency and resolution.

Semiconductor radiation detectors largely overcome the above problems by converting radiation directly into electrical signals. The semiconductor radiation detector may include a semiconductor layer that absorbs radiation at the wavelength of interest. When the radiation particles are absorbed in the semiconductor layer, a plurality of carriers (e.g., electrons and holes) are generated and swept under an electric field toward electrical contacts on the semiconductor layer.

[ summary of the invention ]

Disclosed herein is a radiation detection device comprising: a platform configured to support a human body on a first surface of the platform; a first set of radiation detectors disposed in a first layer, wherein the first set of radiation detectors is connected to a second surface of the platform opposite the first surface; wherein the first set of radiation detectors is configured to detect radiation from a radiation source within the human body.

According to an embodiment, each radiation detector of the first set of radiation detectors is configured to detect an image of the radiation.

According to an embodiment, the first set of radiation detectors comprises two radiation detectors, the area of the first layer between the two radiation detectors being free of any radiation detectors.

According to an embodiment, the radiation is beta rays or gamma rays.

According to an embodiment, at least one radiation detector of the first set of radiation detectors comprises a first radiation absorbing layer configured to absorb the radiation and to generate an electrical signal from the radiation.

According to an embodiment, the first radiation absorbing layer comprises silicon or GaAs.

According to an embodiment, the apparatus further comprises a second set of radiation detectors arranged in a second layer; wherein the second set of radiation detectors is further from the second surface of the platform than the first set of radiation detectors; wherein the second set of radiation detectors is configured to detect radiation from the radiation source.

According to an embodiment, each radiation detector of the second set of radiation detectors is spaced apart from the second surface of the platform by the same distance.

According to an embodiment, each radiation detector of the second set of radiation detectors is configured to detect an image of the radiation.

According to an embodiment, the second set of radiation detectors comprises two radiation detectors, the area of the second layer between the two radiation detectors being free of any radiation detectors.

According to an embodiment, the second set of radiation detectors comprises a second radiation absorbing layer configured to absorb the radiation and to generate an electrical signal from the radiation.

According to an embodiment, the second radiation absorbing layer comprises silicon or GaAs.

According to an embodiment, the apparatus further comprises a processor configured to determine a spatial distribution of the radiation sources in the human body based on the radiation detected by the first set of radiation detectors.

According to an embodiment, the first radiation absorbing layer comprises an electrical contact.

According to an embodiment, wherein the at least one radiation detector comprises: a first voltage comparator configured to compare a voltage of the electrical contact with a first threshold; a second voltage comparator configured to compare the voltage to a second threshold; a counter configured to record the number of radiation particles incident on a pixel of at least one of the radiation detectors; a controller; wherein the controller is configured to initiate a time delay when the absolute value of the voltage is determined from the first voltage comparator to be equal to or exceed the absolute value of the first threshold; wherein the controller is configured to activate the second voltage comparator during the time delay; wherein the controller is configured to increase the number by one when the second voltage comparator determines that the absolute value of the voltage equals or exceeds the absolute value of the second threshold.

Disclosed herein is a method comprising: detecting radiation from a radiation source within the human body using a first set of radiation detectors arranged in a first layer; detecting radiation from the radiation source using a second set of radiation detectors disposed in a second layer; determining a spatial distribution of the radiation source based on the radiation detected by the first set of radiation detectors and the radiation detected by the second set of radiation detectors; wherein the first layer and the second layer are at different distances from the human body.

According to an embodiment, the radiation from the radiation source is detected using the first set of radiation detectors, including detecting an image of the radiation.

According to an embodiment, the first set of radiation detectors comprises two radiation detectors, the area of the first layer between the two radiation detectors being free of any radiation detectors.

According to an embodiment, the first set of radiation detectors comprises a first radiation absorbing layer configured to absorb the radiation and to generate an electrical signal from the radiation.

According to an embodiment, the first radiation absorbing layer comprises silicon or GaAs.

According to an embodiment, the radiation from the radiation source is detected using the second set of radiation detectors, including detecting an image of the radiation.

According to an embodiment, each radiation detector of the second set of radiation detectors is spaced apart from the first layer by the same distance.

According to an embodiment, the second set of radiation detectors comprises two radiation detectors, the area of the second layer between the two radiation detectors being free of any radiation detectors.

According to an embodiment, the second set of radiation detectors comprises a radiation absorbing layer configured to absorb the radiation and to generate an electrical signal from the radiation.

According to an embodiment, the radiation absorbing layer comprises silicon or GaAs.

According to an embodiment, the radiation is beta rays or gamma rays.

[ description of the drawings ]

Fig. 1A, 1B and 2 each schematically show a view of an apparatus according to an embodiment.

Fig. 3 schematically shows an apparatus according to an embodiment having a radiation detector with an array of pixels.

Fig. 4A shows a cross-sectional schematic view of a radiation detector according to an embodiment.

Fig. 4B shows a detailed cross-sectional schematic view of a radiation detector according to an embodiment.

Fig. 4C shows an alternative detailed cross-sectional schematic of a radiation detector according to an embodiment.

Fig. 5A and 5B each show a component diagram of an electronic system of a radiation detector according to an embodiment.

Fig. 6 schematically shows the time variation of the current flowing through the electrical contacts of the radiation absorbing layer of the radiation detector (upper curve), and the corresponding time variation of the voltage of the electrical contacts (lower curve).

Fig. 7 schematically shows a flow chart of a method according to an embodiment.

[ detailed description ] embodiments

Fig. 1A, 1B and 2 each schematically illustrate an apparatus 500 from different views. Fig. 1A shows a first surface 531 of a platform 530 of the device 500. The first surface 531 of the platform 530 may support a human body. Fig. 1B schematically illustrates a second surface 532 of the platform 530. The second surface 532 is opposite to the first surface 531. As shown in fig. 1B and 2, the apparatus 500 has a first set of radiation detectors 521 disposed in a first layer 510. The first set of radiation detectors 521 is attached to the second surface 532. The first set of radiation detectors 521 may include at least two radiation detectors 521. The areas of the first layer 510 between the radiation detectors 521 may be devoid of any radiation detectors.

As schematically shown in fig. 1B and 2, the apparatus 500 has a second set of radiation detectors 522 arranged in a second layer 520, according to an embodiment. The second set of radiation detectors 522 is further from the second surface 532 than the first set of radiation detectors 521. Each radiation detector of the second set of radiation detectors 522 may be spaced apart from the second surface 532 by the same distance. That is, the second layer 520 may be parallel to the second surface 532. The second set of radiation detectors 522 may include at least two radiation detectors 522. The areas of the second layer 520 between the radiation detectors 522 may be free of any radiation detectors. The platform 530 is located between the human body and the radiation detectors 521 and 522. The radiation detectors 521 and 522 may detect radiation from a radiation source within the human body. The radiation detectors 521 and 522 may detect images of the radiation. The radiation may be beta rays or gamma rays.

As shown in fig. 2, the first layer 510 and the second layer 520 are stacked. The second set of radiation detectors 521 in the second layer 520 may be aligned with areas of the first layer 510 that are devoid of any radiation detectors.

The source of radiation within the body may be radioactive material introduced into the body for medical purposes. Examples of the radioactive material may include iodine-131 (I)¹³¹I) Iodine-123 (¹²³I) And iodine-125 (¹²⁵I) In that respect In one example of the above-described method,¹³¹i is used to treat thyrotoxicosis (hyperthyroidism) and certain types of thyroid cancer because the thyroid gland can absorb iodine. In one example of the above-described method,¹³¹i as radiolabels for certain radiopharmaceuticals (e.g.¹³¹I-M-iodobenzoylguanidine (131I-MIBG) is used for imaging and treating pheochromocytoma and neuroblastoma). Thus, knowing the spatial distribution of the radioactive material can facilitate the use of the radioactive material to diagnose or treat certain diseases. The apparatus 500 may have a processor 550, and the processor 550 may determine the spatial distribution of the radiation source based on the radiation detected by the first set of radiation detectors 521 or the second set of radiation detectors 522.

Fig. 3 schematically shows that the radiation detector 100 (which is one of the radiation detectors 521 and 522) may have a pixel array 150 according to an embodiment. The array of pixels 150 may be a rectangular array, a honeycomb array, a hexagonal array, or any other suitable array. The radiation detector 100 may count the number of radiation particles incident on the pixel 150 over a period of time. An example of the radiation particle is a gamma ray photon. Each of the pixels 150 may be configured to measure its dark current, such as before or simultaneously with each radiation particle being incident thereon. The pixels 150 may be configured to operate in parallel. For example, the radiation detector 100 may count one radiation particle incident on one pixel 150 before, after, or while the radiation detector 100 counts another radiation particle on another pixel 150. The pixels 150 may be individually addressable.

Fig. 4A shows a cross-sectional schematic view of a radiation detector 100 according to an embodiment. The radiation detector 100 may comprise a radiation absorbing layer 110 and an electronics layer 120 (e.g. an ASIC) for processing or analyzing electrical signals of incident radiation particles generated in the radiation absorbing layer 110. The radiation detector 100 may or may not include scintillation. The radiation absorbing layer 110 may comprise a semiconductor material such as monocrystalline silicon. The semiconductor may have a high mass attenuation coefficient for the radiant energy of interest.

As shown in the more detailed cross-sectional schematic diagram of the radiation detector 100 according to an embodiment in fig. 4B, the radiation absorbing layer 110 may comprise one or more diodes (e.g., p-i-n or p-n) consisting of one or more discrete regions 114 of first and second doped regions 111, 113. The second doped region 113 may be separated from the first doped region 111 by an optional intrinsic region 112. The discrete regions 114 are separated from each other by the first doped region 111 or the intrinsic region 112. The first and second doped regions 111, 113 have opposite type doping (e.g., region 111 is p-type and region 113 is n-type, or region 111 is n-type and region 113 is p-type). In the example of fig. 4B, each discrete region 114 of the second doped region 113 constitutes a diode together with the first doped region 111 and the optional intrinsic region 112. That is, in the example of fig. 4B, the radiation absorption layer 110 includes a plurality of diodes having the first doped region 111 as a common electrode. The first doped region 111 may also have discrete portions. The radiation absorbing layer 110 may have an electrical contact 119A in electrical contact with the first doped region 111. The radiation absorbing layer 110 can have a plurality of discrete electrical contacts 119B, each of the electrical contacts 119B being in electrical contact with the discrete regions 114.

When a radiation particle strikes the radiation absorbing layer 110 (including a diode), the radiation particle may be absorbed and generate one or more carriers by several mechanisms. The carriers may drift under the electric field toward electrical contact 119A and electrical contact 119B. The electric field may be an external electric field. In an embodiment, the carriers may drift in different directions such that the carriers generated by a single radiating particle are not substantially shared by two different discrete regions 114. ("substantially not shared" here means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow to the discrete region 114 which is different from the remaining carriers). The charge carriers generated by the radiation particles incident around the footprint of one of the discrete regions 114 are substantially not shared by another of the discrete regions 114. The pixel 150 associated with one discrete region 114 may be a region around said discrete region 114 to which substantially all (more than 98%, more than 99.5%, more than 99.9% or more than 99.99%) of the charge carriers generated by the radiation particles incident therein flow towards said discrete region 114. That is, less than 2%, less than 1%, less than 0.1%, or less than 0.01% of these carriers flow out of the pixel 150.

As shown in the alternative detailed cross-sectional schematic diagram of the radiation detector 100 according to an embodiment in fig. 4C, the radiation absorbing layer 110 may comprise a semiconductor material (e.g., monocrystalline silicon) resistor, but not a diode. The semiconductor may have a high mass attenuation coefficient for the radiant energy of interest. The radiation absorbing layer 110 may have an electrical contact 119A on one surface of the semiconductor in electrical contact with the semiconductor. The radiation absorbing layer 110 may have a plurality of electrical contacts 119B on the other surface of the semiconductor.

When a radiation particle strikes the radiation absorbing layer 110, which includes a resistor but does not include a diode, the radiation particle may be absorbed and generate one or more carriers by several mechanisms. One radiation particle can generate 10 to 100000 carriers. The carriers may drift under the electric field toward the electrical contacts 119A and 119B. The electric field may be an external electric field. In an embodiment, the carriers may drift in different directions such that the carriers generated by a single radiating particle are substantially not shared by two electrical contacts 119B ("substantially not shared" here means that less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of these carriers flow to a discrete portion different from the rest of the carriers). Carriers generated by radiation particles incident around the footprint of one electrical contact 119B are substantially not shared by the other electrical contact 119B. The pixel 150 associated with one of the electrical contacts 119B may be a region around it to which substantially all (greater than 98%, greater than 99.5%, greater than 99.9%, or greater than 99.99%) of the carriers generated by one of the radiation particles incident therein flow toward the electrical contact 119B. That is, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01% of the carriers flow out of the pixel associated with the electrical contact 119B.

The electronics layer 120 may comprise electronics systems 121 adapted to process or interpret signals generated by radiation incident on the radiation absorbing layer 110. The electronic system 121 may include analog circuits such as filter networks, amplifiers, integrators, comparators, etc., and digital circuits such as a microprocessor, and memory. The electronic system 121 may include one or more ADCs. The electronic system 121 may include components that are dedicated to a single pixel or shared by pixels. For example, the electronic system 121 may include an amplifier that may be dedicated to each pixel 150 and a microprocessor that is shared among all pixels 150. The electronic system 121 may be electrically connected to the pixels through vias 131. The space between the vias may be filled with a filler material 130 to increase the mechanical stability of the connection of the electron layer 120 to the radiation absorbing layer 110. Other bonding techniques may connect the electronic system 121 to the pixel without using a via.

Fig. 5A and 5B each show a component diagram of an 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, an optional voltage meter 306, and a controller 310.

The first voltage comparator 301 is configured to compare the voltage of at least one electrical contact 119B to a first threshold. The first voltage comparator 301 may be configured to monitor the voltage directly or to calculate the voltage by integrating the current flowing through the current contact 119B over a period of time. The first voltage comparator 301 may be controllably activated or deactivated by the controller 310. The first voltage comparator 301 may be a continuous comparator. That is, the first voltage comparator 301 may be configured to be continuously enabled and monitor the voltage. The first voltage comparator 301 may be a clocked comparator. The first threshold may be 1-5%, 5-10%, 10% -20%, 20-30%, 30-40%, or 40-50% of the maximum voltage that an incident radiation particle may produce on the electrical contact 119B. The maximum voltage may depend on the energy of the incident radiation particles, the material of the radiation absorbing layer 110, and other factors. For example, the first threshold may be 50mV, 100mV, 150mV, or 200 mV.

The second voltage comparator 302 is configured to compare the voltage to a second threshold. The second voltage comparator 302 may be configured to monitor the voltage directly or to calculate the voltage by integrating the current flowing through the diode or electrical contact over a period of time. The second voltage comparator 302 may be a continuous comparator. The second voltage comparator 302 may be controllably activated or deactivated by the controller 310. The power consumption of the second voltage comparator 302 may be less than 1%, less than 5%, less than 10%, or less than 20% of the power consumption when the second voltage comparator 302 is enabled while the second voltage comparator 302 is disabled. The absolute value of the second threshold is greater than the absolute value of the first threshold. 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 to say that the first and second electrodes,the second threshold may be 200% -300% of the first threshold. The second threshold may be at least 50% of the maximum voltage an incident radiation particle may generate at electrical contact 119B. For example, the second threshold may be 100mV, 150mV, 200mV, 250mV, or 300 mV. The second voltage comparator 302 and the first voltage comparator 301 may be the same component. That is, the system 121 may have one voltage comparator that may compare a voltage to two different thresholds at different times.

The first voltage comparator 301 or the second voltage comparator 302 may include one or more operational amplifiers or any other suitable circuitry. The first voltage comparator 301 or the second voltage comparator 302 may have a high speed to allow the system 121 to operate at high incident radiation flux. However, having high speed is usually at the cost of power consumption.

The counter 320 is configured to record at least one radiation particle incident on the pixel 150 surrounding the electrical contact 119B. The counters 320 may be software components (e.g., numbers stored in computer memory) or hardware components (e.g., 4017IC and 7490 IC).

The controller 310 may be a hardware component such as a microcontroller and a microprocessor. The controller 310 is configured to initiate a time delay when the first voltage comparator 301 determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold (e.g., the absolute value of the voltage increases from below the absolute value of the first threshold to a value that equals or exceeds the absolute value of the first threshold). Absolute values are used here because the voltage can be negative or positive, depending on whether the voltage of the cathode or anode of the diode or which electrical contact is used. The controller 310 may be configured to keep disabling the second voltage comparator 302, the counter 320, and any other circuitry not required in the operation of the first voltage comparator 301 until the first voltage comparator 301 determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold. The time delay may terminate before or after the voltage becomes stable (i.e., the rate of change of the voltage is substantially zero). The phrase "the rate of change is substantially zero" means that the temporal change is less than 0.1%/ns. The phrase "the rate of change is substantially non-zero" means that the time change in voltage is at least 0.1%/ns.

The control 310 may be configured to activate the second voltage comparator during a time delay, which includes a start and a stop. In an embodiment, the controller 310 is configured to activate the second voltage comparator at the beginning of the time delay. The term "activate" means to bring a component into an operational state (e.g., by sending a signal such as a voltage pulse or logic level, by providing power, etc.). The term "disable" means to bring a component into a non-operational state (e.g., by sending a signal such as a voltage pulse or logic level, by cutting 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. The controller 310 itself may be disabled until the absolute value of the output voltage of the first voltage comparator 301 equals or exceeds the absolute value of the first threshold value to activate the controller 310.

If, during the time delay, the second voltage comparator 302 determines that the absolute value of the voltage equals or exceeds the absolute value of the second threshold, the controller 310 may be configured to increment the number of records of one of the counters 320 by one.

The controller 310 may be configured to cause the optional voltmeter 306 to measure voltage upon expiration of the time delay. The controller 310 may be configured to connect the electrical contact 119B to electrical ground to reset the voltage and discharge any carriers accumulated on the electrical contact 119B. In an embodiment, the electrical contact 119B is connected to electrical ground after the time delay has expired. In an embodiment, the electrical contact 119B is connected to electrical ground for a limited reset period. The controller 310 may connect the electrical contact 119B to electrical ground by controlling the switch 305. The switch may be a transistor such as a Field Effect Transistor (FET).

In an embodiment, the system 121 does not have an analog filter network (e.g., an RC network). In an embodiment, the system 121 has no analog circuitry.

The voltmeter 306 can feed the voltage it measures to the controller 310 as an analog or digital signal.

The electronic system 121 can include an integrator 309 electrically connected to the electrical contact 119B, wherein the integrator is configured to collect carriers from the electrical contact 119B. The integrator 309 may include a capacitor in the feedback path of the amplifier. An amplifier so configured is referred to as a capacitive transimpedance amplifier (CTIA). The CTIA has a high dynamic range by preventing the op-amp from saturating and improves the signal-to-noise ratio by limiting the bandwidth in the signal path. Carriers from the electrical contact 119B accumulate on the capacitor over a period of time ("integration period"). After the end of the integration period, the capacitor voltage is sampled and then reset by a reset switch. The integrator 309 may include a capacitor directly connected to the electrical contact 119B.

Fig. 6 schematically shows the time variation of the current caused by carriers generated by radiation particles incident on the pixel 150 surrounding the electrical contact 119B flowing through said electrical contact 119B (upper curve) and the corresponding time variation of the voltage of said electrical contact 119B (lower curve). The voltage may be an integral of the current with respect to time. At time t₀The radiation particles strike the pixel 150, carriers begin to be generated in the pixel 150, current begins to flow through the electrical contact 119B, and the absolute value of the voltage at the electrical contact 119B begins to increase. At time t₁The first voltage comparator 301 determines that the absolute value of the voltage equals or exceeds the absolute value of the first threshold V1, the controller 310 activates a time delay TD1 and the controller 310 may deactivate the first voltage comparator 301 when the TD1 starts. If the controller 310 is at t₁Is previously deactivated at t₁The controller 310 is activated. During the TD1, the controller 310 activates the second voltage comparator 302. The term "during" a time delay as used herein means beginning and ending (i.e., ending) and any time in between. For example, the controller 310 may activate the second voltage comparator 302 when the TD1 terminates. If during the TD1, the second voltage comparator 302 determines at time t₂The absolute value of the voltage equals or exceeds the absolute value of the second threshold, the controller 310 waits for the voltage to stabilize. Said voltage being at time t_eStable, when all carriers generated by the radiation particles drift out of the radiation absorbing layer 110. At time t_sThe time delay TD1 ends. At time t_eOr t_eThe controller 310 then causes the ADC 306 to digitize the voltage and determine in which bin the energy of the radiating particle falls. The controller 310 then increments the number of counter 320 records corresponding to the bin by one. In the example of FIG. 6, time t_sAt time t_eThen; that is, TD1 terminates after all carriers generated by the radiation particles drift out of radiation absorbing layer 110. If the time t cannot be easily measured_eTD1 may be empirically selected to allow sufficient time to collect substantially all of the carriers generated by the radiating particles, but TD1 cannot be too long, otherwise there is a risk that carriers generated by another incident radiating particle will be collected. That is, TD1 may be empirically selected such that t_sEmpirically at time t_eAnd then. Because once V2 is reached, controller 310 may ignore TD1 and wait time t_eTime t_sNot necessarily at time t_eAnd then. Thus, the rate of change of the difference between the voltage and the dark current contribution to the voltage is at t_eIs substantially zero. The controller 310 may be configured to terminate at TD1 or at t₂Or disable the second voltage comparator 302 at any time in between.

At time t_eIs proportional to the number of carriers generated by the radiating particles, which number is related to the energy of the radiating particles. The controller 310 may be configured to determine the energy of the radiation particles using the voltmeter 306.

After TD1 terminates or is digitized by voltmeter 306 (whichever is later), controller 310 connects electrical contact 119B to electrical ground for a reset period RST to allow the carriers accumulated on electrical contact 119B to flow to ground and reset the voltage. After RST, the system 121 is ready to detect another incident radiation particle. If the first voltage comparator 301 is disabled, the controller 310 may enable RST at any time before it terminates. If the controller 310 is disabled, it may be activated before RST terminates.

Fig. 7 schematically shows a flow chart of a method according to an embodiment. In step 801, radiation emitted by a radiation source from within the human body is detected by a first set of radiation detectors 521. In step 802, the radiation is detected by a second set of radiation detectors 522. In step 803, the spatial distribution of the radiation source within the human body is determined based on the radiation detected by the first set of radiation detectors 521 and the radiation detected by the second set of radiation detectors 521.

While 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 purposes of illustration and not limitation, and their true scope and spirit should be determined by the claims herein.