Abstract: According to an embodiment, a photon detecting element includes one or more avalanche photodiodes and a circuit. The circuit is connected between cathodes of the one or more avalanche photodiodes and an external power source. The circuit is configured in which a first temperature coefficient representing variation of a setting potential with respect to temperature variation when constant-current driving is performed so that electrical potential of the cathodes becomes equal to the setting potential is substantially the same as a second temperature coefficient representing variation of breakdown voltage of the one or more avalanche photodiodes with respect to temperature variation.

Abstract: According to an embodiment, a photon counting CT apparatus includes a scintillator, a photodiode array, a holder, a divider, and an image generator. The scintillator is configured to convert X-rays into light. The array includes first and second pixels. The first pixel includes a photodiode in a first range receiving the light emitted from the scintillator. The photodiode outputs an electrical signal based on the light. The second pixel includes a photodiode in a second range different from the first range. The holder is circuitry configured to hold a value of an electrical signal output by the second pixel. The divider circuitry is configured to count the number of photons of light incident on the first pixel by dividing an integrated value of electrical signals output by the first pixel by the held value. The image generator is circuitry configured to reconstruct an image based on the counted number.

Abstract: An integration circuit according to one embodiment includes a first capacitance element, a capacitance circuit, a comparison circuit, a memory circuit and an operation circuit. The first capacitance element receives a current signal. The capacitance circuit includes a first switch and a second capacitance element, and is connected in parallel to the first capacitance element. The second capacitance element receives a current signal via the first switch. The comparison circuit compares a voltage of the first capacitance element with a reference voltage to obtain a comparison result. The memory circuit stores the comparison result, and opens or closes the first switch based on the comparison result. The operation circuit outputs a residual signal based on a difference between the integrated value obtained by the first capacitance element and the second capacitance element and a value based on the comparison result.

Abstract: According to an embodiment, a photodetector includes a plurality of photoelectric transducers, a plurality of resistors, and a plurality of resetting sections. Each of the photoelectric transducers is configured to output a detection signal resulting from, conversion of received light into an electric charge. Each of the resistors is connected in series with an output end of a corresponding photoelectric transducer at one end of the resistor. Each of the resetting sections is connected in parallel with a corresponding resistor and configured to bring the output end of the corresponding photoelectric transducer to a reset level in response to the detection signal.

Abstract: According to an embodiment, a signal processing device includes an integrator, a first analog-to-digital converter, and a histogram creator. The integrator is configured to integrate an electrical charge corresponding to electromagnetic waves. The first analog-to-digital converter is configured to perform an analog-to-digital conversion operation that generates digital data of the electrical charge using an integration output from the integrator, on a parallel with an integration operation performed by the integrator. The histogram creator is configured to create a histogram that represents an energy distribution of the electromagnetic waves, from the digital data generated by the first analog-to-digital converter.

Abstract: A current detection circuit according to one embodiment includes a low-pass filter, a voltage-to-current converter circuit, and a comparator. The low-pass filter has a first terminal connected to a signal input terminal to which a signal current is input. The voltage-to-current converter circuit has a first terminal connected to a second terminal of the low-pass filter and has a second terminal connected to the signal input terminal. The comparator has a first input terminal and a second input terminal and outputs a signal according to a difference between a signal input through the first input terminal and a signal input through the second input terminal, the first input terminal being connected to the second terminal of the low-pass filter, and the second input terminal being connected to the second terminal of the voltage-to-current converter circuit.

Abstract: A radiation detection apparatus according to an embodiment includes: a scintillator; a photon detection device array including a plurality of cells each being a photon detection device with an avalanche photodiode configured to detect visible radiation photons emitted from the scintillator and a resistor disposed along a part of a periphery of an active region of the avalanche photodiode; and a reflector configured to reflect a visible radiation photon and disposed in a region that does not include the active regions and the resistors of the cells, on a face including the active regions.

Abstract: There is provided a single to differential conversion circuit including: a divider circuit, first and second bias current generators, first and second output terminals and a current generating circuit. The divider circuit receives an input current including a DC component and an AC component and divides the input current to generate a first current and a second current. The first bias current generator generates a first bias current. The first output terminal outputs a first output current depending on a difference between the first current and the first bias current. The current generating circuit generates a third current which has a sign opposite to the second current on the basis of the second current. The second bias current generator generates a second bias current. The second output terminal outputs a second output current depending on a difference between the third current and the second bias current.

Abstract: A radiation detection apparatus according to an embodiment includes: a scintillator including a fluorescent material to convert radiation to visible radiation photon; a photon detection device array having a plurality of cells each of which includes a photon detection device to detect visible radiation photon emitted from a fluorescent material in the scintillator and convert the visible radiation photon to an electric signal; and a plurality of lenses provided on cells respectively in association with the cells to cause the visible radiation photon to be incident on the photon detection device in an associated cell.

Abstract: In one embodiment, a buffer circuit includes a first transistor, a second transistor, a first current source, a third transistor, a fourth transistor, a second current source, and a third current source. The first transistor has a control terminal connected to an input terminal, and a first terminal connected to an output terminal. The second transistor has a control terminal connected to the input terminal, a first terminal connected to the output terminal, and a second terminal connected to a first power source. The third transistor has a first terminal connected to the output terminal. The fourth transistor has a first terminal connected to the second terminal of the first transistor, a control terminal applied bias voltage, and a second terminal connected to a control terminal of the third transistor.

Abstract: In one embodiment, a differential amplifier circuit includes a first input terminal, a second input terminal, a first transistor, a second transistor, a third transistor, a current source, a first output terminal, a second output terminal, a first passive element, and a second passive element. The first (second) transistor has a control terminal connected to the first (second) input terminal. The third transistor has a control terminal. The control terminal is applied predetermined bias voltage. The current source is connected to a first terminal in each of the first transistor, second transistor, and third transistor. The first (second) output terminal is connected to a second terminal of the first (second) transistor. The first (second) passive element is connected between the first (second) input terminal and the first (second) output terminal.

Abstract: According to an embodiment, a signal processing device includes an integrator, a first analog-to-digital converter, and a histogram creator. The integrator is configured to integrate an electrical charge corresponding to electromagnetic waves. The first analog-to-digital converter is configured to perform an analog-to-digital conversion operation that generates digital data of the electrical charge using an integration output from the integrator, on a parallel with an integration operation performed by the integrator. The histogram creator is configured to create a histogram that represents an energy distribution of the electromagnetic waves, from the digital data generated by the first analog-to-digital converter.

Abstract: A radiation detector according to an embodiment includes: a semiconductor substrate; a light detecting unit provided on a side of a first surface of the semiconductor substrate; a first insulating film provided covering the light detecting unit; a second insulating film covering the first insulating film; a scintillator provided on the second insulating film; an interconnection provided between the first and second insulating films, and connected to the light detecting unit; a first electrode connected to the interconnection through a bottom portion of the first opening; a second electrode provided on a region in the second surface of the semiconductor substrate, the region opposing at least a part of the light detecting unit; a second opening provided in a region surrounding the first electrode and not surrounding the second electrode; and an insulating resin layer covering the first and second electrodes and the first and second openings.

Abstract: According to an embodiment, a signal processing device includes an integrator, a setting unit, and an analog-to-digital converter. The integrator is configured to integrate an electrical charge corresponding to electromagnetic waves. The integrator includes a capacitor configured to store the electrical charge corresponding to the electromagnetic waves and a discharging circuit configured to discharge the capacitor. The setting unit is configured to set a period of integration of the electrical charge with respect to the integrator. The analog-to-digital converter includes a comparator configured to compare an integration output and a threshold value and a counter configured to output, as digital data of the electrical charge, the number of times for which a value of the integration output becomes not less than the threshold value. The converter is configured to discharge the capacitor during the period of integration by supplying a comparison output of the comparator to the discharging circuit.

Abstract: According to an embodiment, a signal processing device includes an integrator, a setting unit, and an analog-to-digital converter. The integrator is configured to integrate an electrical charge corresponding to electromagnetic waves. The integrator includes a capacitor configured to store the electrical charge corresponding to the electromagnetic waves and a discharging circuit configured to discharge the capacitor. The setting unit is configured to set a period of integration of the electrical charge with respect to the integrator. The analog-to-digital converter includes a comparator configured to compare an integration output and a threshold value and a counter configured to output, as digital data of the electrical charge, the number of times for which a value of the integration output becomes not less than the threshold value. The converter is configured to discharge the capacitor during the period of integration by supplying a comparison output of the comparator to the discharging circuit.

Abstract: A radiation detection apparatus according to an embodiment includes: a scintillator including a fluorescent material to convert radiation to visible radiation photon; a photon detection device array having a plurality of cells each of which includes a photon detection device to detect visible radiation photon emitted from a fluorescent material in the scintillator and convert the visible radiation photon to an electric signal; and a plurality of lenses provided on cells respectively in association with the cells to cause the visible radiation photon to be incident on the photon detection device in an associated cell.