A method and apparatus are provided for positron emission imaging to correct a recorded energy of a detected gamma ray, when the gamma ray is scattered during detection. When scattering occurs, the energy of a single gamma ray can be distributed across multiple detector elementsa multi-channel detection. Nonlinearities in the detection process and charge/light sharing among adjacent channels can result in the summed energies from the multiple crystals of a multi-channel detection deviating from the energy that would be measured in single-channel detection absent scattering. This deviation is corrected by applying one or more correction factors (e.g., multiplicative or additive) that shifts the summed energies of multi-channel detections to agree with a known predefined energy (e.g., 511 keV). The correction factors can be stored in a look-up-table that is segmented to accommodate variations in the multi-channel energy shift based on the level of energy sharing.

According to various embodiments, the present disclosure provides a collimator for medical imaging. The collimator includes a perforated plate with a top surface and a bottom surface and holes distributed on the perforated plate. The holes are arranged in a plurality of groups. The plurality of groups forms a first coded aperture pattern and the holes in each of the plurality of groups form a second coded aperture pattern.

According to various embodiments, the present disclosure provides a method of imaging reconstruction. The method of imaging reconstruction includes providing a target object, a detector, and a mask disposed between the target object and the detector; acquiring a measured image of the target object by the detector; providing an estimated image of the target object; partitioning the mask into multiple regions; for each of the regions, deriving a forward projection from the estimated image of the target object and the respective region, thereby acquiring multiple forward projections; comparing the measured image of the target object with the forward projections; and updating the estimated image of the target object based on a result of the comparing.

A higher accuracy beam hardening correction with a low calculation load is performed with objects whose elements have a wider range of effective atomic numbers Z.sub.eff, thereby contributing to presentation of more quantitative X-ray images. Of two or more X-ray energy bins, two X-ray bins are selected to normalize X-ray attenuation amount t in those bins such that one or more normalized X-ray attenuation amounts are obtained at each pixel areas. From reference information indicating a theoretical relationship of correspondence between the normalized X-ray attenuation amounts and effective atomic numbers of elements, one ore more effective atomic numbers are estimated every pixel area. Among the one or more effective atomic numbers (Z.sub.High, Z.sub.Low) and an effective atomic number (Zm) preset for the beam hardening correction, two or more atomic numbers are subjected to their equality determination.

A method and apparatus are provided for positron emission imaging to calibrate energy measurements of a pixilated gamma-ray detector using energy sharing events between channels of the detector. Due to conservation of energy, when the energy of a single gamma ray shared among multiple channels, the sum of measured energies across the respective channel must equal the original energy of the incident gamma ray. Further, the fractions of the original energy distributed to the respective channels can span the entire range of zero to the original energy. Thus, a single gamma-ray source (e.g., cesium isotope 137) can be used to continuously calibrate the nonlinear energy response of the detector over an entire range of interest.

A tomographic imaging apparatus includes an X-ray detector comprising a plurality of dual mode pixels and configured to detect radiation that has passed through an object, and at least one processor configured to obtain scan data from the X-ray detector, and control each pixel of the plurality of dual mode pixels to operate in one of a first mode and a second mode, wherein each pixel of the plurality of dual mode pixels includes a sensor configured to generate a scan signal by converting incident radiation into an electric signal, a first signal path circuit configured to transmit the scan signal in the first mode, a second signal path circuit configured to transmit the scan signal in the second mode, and a photon counter configured to count photons from the scan signal transmitted through one of the first and second signal path circuits.

A method for normalization of a positron emission tomography (PET) scanner. The PET scanner includes a plurality of blocks. Each of the plurality of blocks includes a plurality of rows. Each of the plurality of rows includes a plurality of actual detectors and an unused area. The method includes acquiring a plurality of lines of response (LORs) by scanning a normalization phantom, obtaining a plurality of actual counts by extracting a plurality of LORs subsets from the plurality of LORs and counting a number of elements in each LORs subset, generating a plurality of virtual detectors in each of the plurality of rows by assigning the unused area to the plurality of virtual detectors, generating a count profile for the plurality of actual detectors, estimating a plurality of virtual counts based on the count profile, and applying a normalization process on the plurality of blocks.

A method and apparatus are provided for positron emission imaging to correct a recorded energy of a detected gamma ray, when the gamma ray is scattered during detection. When scattering occurs, the energy of a single gamma ray can be distributed across multiple detector elementsa multi-channel detection. Nonlinearities in the detection process and charge/light sharing among adjacent channels can result in the summed energies from the multiple crystals of a multi-channel detection deviating from the energy that would be measured in single-channel detection absent scattering. This deviation is corrected by applying one or more correction factors (e.g., multiplicative or additive) that shifts the summed energies of multi-channel detections to agree with a known predefined energy (e.g., 511 keV). The correction factors can be stored in a look-up-table that is segmented to accommodate variations in the multi-channel energy shift based on the level of energy sharing.

A multichannel ASIC for interfacing with an array of photodetectors in a PET imaging system includes a front-end circuit configured to be coupled to the array of photodetectors and to receive analog signals therefrom. The ASIC includes a time discriminating circuit including a low input impedance amplifier configured to be coupled to the array of photodetectors and to receive a signal summing the analog signals from the array of photodetectors and to generate a hit signal for timing pickoff based on the signal. The ASIC includes an energy circuit operably coupled to the front-end circuit and configured to generate a summed energy output signal based on each of the analog signals and summed positional output signal based on each of the analog signals.

A SiPM sensor chip with a plurality of pixels includes a photodiode; a quench resistor; and a current divider configured to divide the photocurrent of the photodiodes into two currents of equal size. The current divider Sq,nm or Snm lead to networks NS,h,n and NS,V,m, each of which leads to additional current dividers Sh,n and Sv m having coding resistors Rh,A,n and Rh,B,n, and Rv,c,m and Rv D m, which are linearly coded and which lead to output channels A, B, C, D, with these sensor features being integrated into the sensor chip. The networks Ns,h,n and/or NSiVlm each lead to a summation network Oh and/or Ov, in which the signals of the networks Ns,h,n and/or NS,v,m are merged via summation resistors Rs,h,n and Rs,v,m, respectively, and lead to the output channels E and/or F.