Various aspects include circuits and methods for use in X-ray detectors for obtaining time information regarding when an indication of an X-ray photon's energy, such as a CSA output voltage, and using the time information to obtain temporal-spectral data regarding an X-ray photon detection. The temporal-spectral data may be used to determine the X-ray photon's energy, to detect and account for multiple X-ray photon detection events (“pile ups”), and/or accommodating detection events in which charge is shared between two pixel detectors.

The invention relates to radiation detector for registering incident photons, comprising (i) detection circuitry (202, 206, 207) configured to provide an electric output signal in response to incident photons, the output signal comprising pulses having an amplitude indicative of energies deposited in the radiation detector by the incident photons, and (ii) an energy estimating circuit (208.sub.1, . . . , 208.sub.N; 209.sub.1, . . . , 209.sub.N) configured to detect that the output signal is larger than at least one threshold corresponding to an energy value in order to determine energies of incident photons. The radiation detector further comprises a registration circuit (211) configured to detect incident photons independent of a comparison of the output signal with the at least one threshold. Moreover, the invention relates to a method for detecting photons using the radiation detector.

An apparatus and method are described using a forward model to correct pulse pileup in spectrally resolved X-ray projection data from photon-counting detectors (PCDs). The forward model represents pulse pileup effects using an integral in which the integrand includes a term that is a function of a count rate, which term is called a spectrum distortion correction function. This correction function can be represented as superposition of basis energy functions and corresponding polynomials of the count rate, which are defined by the polynomial coefficients. To calibrate the forward model, the polynomial coefficients are adjusted to optimize an objective function, which uses calibration data having known projections lengths for the material components of a material decomposition. To determine projection lengths for projection data from a computed tomography scan, the calibrated polynomial coefficients are held constant and the projection lengths are adjusted to optimize an objective function.

Techniques are disclosed for systems and methods to provide a radiation detector module for a radiation detector. A radiation detector module includes a metallic and/or metalized enclosure, a radiation sensor disposed within the enclosure, readout electronics configured to provide radiation detection event signals corresponding to incident ionizing radiation in the radiation sensor, and a cap including an internal interface configured to couple to the readout electronics and an external interface configured to couple to a radiation detector, where the cap is configured to hermetically seal the radiation sensor within the enclosure. The cap may be implemented as an edge plated printed circuit board (PCB) including a slot configured to mate with a planar edge of an open surface of the enclosure, where the slot is soldered to the planar edge of the enclosure to hermetically seal the radiation sensor within the enclosure.

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.

There are provided a storage section 220 that stores an output value read out by counting a pulse signal of incident X-rays, by a photon-counting type semiconductor detector; and a calculation section 230 that calculates a count value based on the output value that has been read out, wherein the calculation section 230 uses a model in which an apparent time constant of the pulse signal monotonously decreases against increase in pulse detection ratio with respect to exposure. According to such a model, the corresponding apparent time constant is able to be obtained even in any higher count rate. As a result of this, reduced can be the influence of count loss even on the count rate that has not been able to be covered by the conventional method.

Various aspects include methods for use in X-ray detectors for adjusting count measurements from pixel detectors within a pixelated detector module to correct for the effects of pileup events that occur when more than one photon is absorbed in a pixel detector during a deadtime of the detector system. In various embodiments, count measurements may be obtained at two different X-ray tube currents, from which the detector system deadtime may be calculated based on the two count measurements and a ratio of the two X-ray tube currents. Using the calculated deadtime, a pileup correction factor may be determined appropriate for the behavior of the detector system in response to pileup events. The pileup correction factor may be applied to pixel detector count values after the counts have been corrected for pixel-to-pixel differences using a flat field correction.

An apparatus and method are described using a forward model to correct pulse pileup in spectrally resolved X-ray projection data from photon-counting detectors (PCDs). The forward model represents pulse pileup effects using an integral in which the integrand includes a term that is a function of a count rate, which term is called a spectrum distortion correction function. This correction function can be represented as superposition of basis energy functions and corresponding polynomials of the count rate, which are defined by the polynomial coefficients. To calibrate the forward model, the polynomial coefficients are adjusted to optimize an objective function, which uses calibration data having known projections lengths for the material components of a material decomposition. To determine projection lengths for projection data from a computed tomography scan, the calibrated polynomial coefficients are held constant and the projection lengths are adjusted to optimize an objective function.

Disclosed is a method for modelling a distorted energy spectrum in a multi-energy x-ray CT imaging system using probability distribution functions, the method including taking open beam measurements across a range of fluxes, estimating true interaction rates from said fluxes, calculating the probabilities of photons being counted, pileup order, and counts recorded to produce a model of the distorted energy spectrum. Also described are computer implemented methods and systems for modelling distortions and optimizing material images produced from multi-energy x-ray CT scanning systems using the modelling techniques.

For dead time determination for a gamma camera or other detector, a long-lived point source of emissions is positioned so that the gamma camera detects the emissions from the source while also being used to detect emissions from the patient. The long-lived point source, in the scan time, acts as a fixed frequency source of emissions, allowing for dead time correction measurements that include the crystal detector effects.