Charge sharing correction methods for pixelated radiation detector arrays
Various aspects include methods of compensating for issues caused by charge sharing between pixels in pixel radiation detectors. Various aspects may include measuring radiation energy spectra with circuitry capable of registering detection events occurring simultaneous or coincident in two or more pixels, adjusting energy measurements of simultaneous-multi-pixel detection events by a charge sharing correction factor, and determining a corrected energy spectrum by adding the adjusted energy measurements of simultaneous-multi-pixel detection events to energy spectra of detection events occurring in single pixels. Adjusting energy measurements of simultaneous-multi-pixel detection events may include multiplying measured energies of simultaneous-multi-pixel detection events by a factor of one plus the charge sharing correction factor.
1. A method for correcting spectra measured by a pixel radiation detector to account for inter-pixel charge sharing effects, comprising:
measuring radiation energy spectra by a pixel radiation detector capable of registering simultaneous, coincident detection events occurring in two or more pixels;
adjusting energy measurements of detection events occurring simultaneously in two or more pixels by a charge sharing correction factor;
determining a corrected energy spectrum by adding the adjusted energy measurements of detection events occurring simultaneously in two or more pixels to energy spectra of detection events occurring in single pixels; and
determining the charge sharing correction factor by:
creating a first energy spectra for detection events occurring in single pixels and determining its peak value V peak1 ;
creating a second energy spectra for detection events occurring simultaneously in two or more pixels and determining its peak value V peak2 ; and
calculating the charge sharing correction factor as (V peak1 −V peak2 )/V peak2 .
2. The method of claim 1 , wherein adjusting energy measurements of detection events occurring simultaneously in two or more pixels by a charge sharing correction factor comprises multiplying measured energies of detection events occurring simultaneously into more pixels by a factor of one plus the charge sharing correction factor.
3. A method of calibrating a pixel radiation detector to account for inter-pixel charge sharing effects, comprising:
measuring radiation energy spectra from a radiation source having a known gamma photon energy by the pixel radiation detector using electronics capable of registering simultaneous, coincident detection events occurring in two or more pixels;
recording energies measured in adjoining pixels for detection events occurring simultaneously in two or more pixels; and
determining a charge sharing correction factor based upon the radiation source known gamma photon energy and recorded energies measured in adjoining pixels for detection events occurring simultaneously in two or more pixels,
wherein the method is performed as part of manufacturing the pixel radiation detector.
4. The method of claim 3 , wherein determining a charge sharing correction factor based upon the radiation source known gamma photon energy and recorded energies measured in adjoining pixels for detection events occurring simultaneously in two or more pixels comprises:
creating a first energy spectra for detection events occurring in single pixels and determining its peak value V peak1 ;
creating a second energy spectra for detection events occurring simultaneously in two or more pixels and determining its peak value V peak2 ; and
calculating the charge sharing correction factor as (V peak1 −V peak2 )/V peak2 .
5. The method of claim 3 , further comprising storing the charge sharing correction factor in memory associated with the pixel radiation detector.
6. A Single Photon Emission Computed Tomography (SPECT) imaging system, comprising:
a pixel radiation detector; and
an analysis unit configured to receive data from the pixel radiation detector and output analyzed data to a digital image processing computer, wherein the analysis unit is configured to perform operations of:
adjusting energy measurements of detection events occurring simultaneously in two or more pixels by a charge sharing correction factor; and
determining a corrected energy spectrum by adding the adjusted energy measurements of detection events occurring simultaneously in two or more pixels to energy spectra of detection events occurring in single pixels, wherein determining the corrected energy spectrum comprises:
creating a first energy spectra for detection events occurring in single pixels and determining its peak value V peak1 ;
creating a second energy spectra for detection events occurring simultaneously in two or more pixels and determining its peak value V peak2 ; and
calculating the charge sharing correction factor as (V peak1 −V peak2 )/V peak2 .