A photon counting circuit, a radiographic imaging apparatus, and a threshold setting method are provided, in which the photon counting circuit is capable of sufficiently reducing a difference between a target threshold value and a threshold value set for a pixel even if each pixel of a photon counting detector is divided into a plurality of subpixels. In the photon counting circuit for counting, for each pixel, electrical charges generated depending on photon energy of radiation applied to an object, a pixel is divided into a plurality of subpixels. When N is a natural number, a threshold value of each of the subpixels is selected from among top N discrete values of a plurality of discrete values arranged in order of proximity to a target threshold value corresponding to the photon energy so as to minimize a difference between the target threshold value and an average of the threshold values of the respective subpixels included in the pixel.

There are provided a radiation detector capable of detecting radiation without occurrence of dead time while maintaining an exposure state in which radiation enters continuously, and an X-ray analysis apparatus and a radiation detection method using the radiation detector. A radiation detector 100 that detects radiation in synchronization with an external apparatus 200, includes: a sensor 110 that generates pulses when radiation particles are detected; a plurality of counters 140a, 140b provided so as to be able to count the pulses; and a control circuit 160 configured to switch a counter to count the pulses among the plurality of counters 140a, 140b, when receiving a synchronization signal from the external apparatus 200.

A positron emission tomography (PET) apparatus and method employs a plurality of radiation detectors (20) disposed around an imaging region (16) and configured to detect 511 keV radiation events emanating from the imaging region. A calibration phantom is disposed in the imaging region. One or more processors are configured to: acquire and store listmode data of the phantom; measure a random rate for each line of response (LOR) from the listmode data using a coincident 511 keV events detector (34) with a time offset (54); determine a singles rate for each detector pixel from the random event rate, for example via a histogram plotting singles rate for each detector pixel; compute a live time factor of each LOR; compute a dead time correction factor as the reciprocal of the live time factor; and correct images according to the dead time correction factor.

A method of detection of radiation is described. The method comprises providing at least one source of radiation; providing at least one detector capable of detecting radiation from the source; causing said source to emit radiation along a predetermined radiation path towards said detector; during a measurement period, detecting successive count events corresponding to photons from the source detected by the detector; measuring a duration of each such count event to determine a dead time associated with each count event; calculating a total dead time for the measurement period as the sum of each determined dead time associated with each count event; determining a photon count rate from the total number of count events during the measurement period; calculating a corrected count rate by applying a correction factor based on subtracting the total dead time from the measurement period. A method of scanning an object and apparatus for performing the methods are also disclosed.

The invention relates to a detection apparatus (12) for detecting photons. The detection apparatus comprises a pile-up determining unit (15) for determining whether detection signal pulses being indicative of detected photons are caused by a pile-up event or by a non-pile-up event, wherein a detection values generating unit (16) generates detection values depending on the detection signal pulses and depending on the determination whether the respective detection signal pulse is caused by a pile-up event or by a non-pile-up event. In particular, the detection values generating unit can be adapted to reject the detection signal pulses caused by pile-up events while generating the detection values. This allows for an improved quality of the generated detection values.

According to embodiment, an X-ray computed tomography apparatus includes an X-ray tube, an X-ray detector including a scintillator generating scintillation light upon incidence of X-ray photons and a photodetection element, a peak value detector detecting peak values corresponding to X-ray photons based on an output signal from the element, processing circuitry determining an attenuation characteristic of the light by each X-ray photon and an output decreased characteristic of the element, based on the values and time when each peak value was detected, correcting the detected values according to the characteristics, a counter counting the X-ray photons corresponding to the respective corrected peak values, wherein the processing circuitry reconstructs a medical image based on an output from the counter.

According to an embodiment, a signal processing device includes a first integrator, a second integrator, a switcher, and a calculator. The first integrator is configured to integrate a current represented by a reference waveform equivalent to a normal waveform in a case of no pileup phenomenon regarding the current to calculate a first electrical charge. The second integrator is configured to integrate a current output from a photoelectric converter to calculate a second electrical charge. The switcher is configured to, when a pileup phenomenon has occurred, perform switching either to a state in which the first and second electrical charges are output or to a state in which the first electrical charge and a reference charge are output. The calculator is configured to calculate a first difference charge between the first and second electrical charges, and calculate a second difference charge between the first electrical charge and the reference charge.

There is provided a method and corresponding system and apparatus for image reconstruction based on image data from a photon-counting multi-bin x-ray detector. The method includes determining (S1) parameter(s) of a given functional form of the relationship between comparator settings expressed in voltage in the read-out chain of the x-ray detector and the corresponding energy threshold values expressed in energy based on a fitting procedure between a first set of data representative of a measured pulse height spectrum and a second set of data representative of a reference pulse height spectrum. The method also includes performing (S2) image reconstruction based on the image data and the determined parameter(s). In this way, efficient high-quality image reconstruction can be achieved.

A system includes a pulse counter having a selectable pulse counter read-out rate, a pulse counter read-out (PCRO) storage register that stores a PCRO count, and a pulse-burst counter that has a pulse-burst counter read-out rate that is faster than all but the fastest selectable pulse counter read-out rate, a subtractor module in electronic communication with the pulse counter and the PCRO that subtracts the PCRO count from the pulse counter read-out count to output an uncorrected pulse count, a selection module in electronic communication with the pulse-burst counter that selects the pulse counter read-out rate in response to input from the pulse-burst counter, a multiplexer in electronic communication with the subtractor module and the selection module, the multiplexer selecting from among at least two dead-time correction transforms, the transform corresponding to the selected pulse counter read-out rate, and a control-and-readout module that outputs a dead-time corrected pulse rate.

In an X-ray scanning apparatus including a photon counting type X-ray detection element, in order to perform counted number correction specialized for pile-up with high accuracy, the X-ray scanning apparatus includes an X-ray detector in which a plurality of photon counting type X-ray detection elements are disposed, each of the X-ray detection elements detecting an incident X-ray photon, classifying energy of the X-ray photon into two or more energy ranges, and counting the X-ray photon, and a correction unit that corrects the counted number in the X-ray detection element, in which the correction unit includes a counting error amount determination part that determines a counting error amount in a counted number due to pile-up according to a pile-up occurrence probability in two or more X-ray photons