Characterization of a 64 channel PET detector using photodiodes for crystal identification

An LSO scintillator array for a PET detector module with depth of interaction measurement

“…2, with a PD array attached and/or with black tape used as a "mock" PD to imitate the optical properties of the PD array. The detector module is excited with a beam of 511 keV photons that is electronically collimated using a single 3 mm x 3 mm x 30 mm BGO crystal coupled to a photomultiplier tube, allowing a 5 mm fwhm portion of the detector module to be excited at an arbitrary depth of interaction [8]. The PMT signal is read out whenever the photomultiplier tube detects an energy deposit greater than 150 keV in time coincidence with the collimating photomultiplier tube.…”

“…Our production lutetium oxyorthosilicate (LSO) scintillator [7] arrays have been developed for a PET detector module capable of measuring depth of interaction on an event by event basis [8]. With this design, a single photomultiplier tube provides an accurate timing pulse and initial energy discrimination for an 8x8 array of 3 mm square LSO scintillator crystals, an 8x8 silicon photodiode array identifies the crystal of interaction, the ratio of the photomultiplier tube (PMT) and photodiode signal (PD) measures interaction depth, and the sum (PD+PMT) provides a total energy signal.…”

3D reconstruction in PET cameras with irregular sampling and depth of interaction

“…For this purpose, we simulate a flood phantom and calculate the mean and variance of pixels at various locations of the reconstructed image as a function of the polar acceptance. Event generation, detector simulation, DOI measurement, and normalization are the same as discussed in [2]. The normalization data contains an order of magnitude more events than the reconstructed data.…”

“…This eliminates most of the ZEBs that we encounter in our final algorithm, as they are the result of fine (d/4) radial sampling. We initially use coarse fixed-width (FW) [2] angular sampling in θ and φ, i.e. δθ = δφ = 0.050 (except δθ π/2 = δφ 0 = δφ π = 0.075), but later use fine FW sampling in φ, i.e.…”

“…We therefore measure the depth of interaction (DOI) to increase the sampling rate of the camera and to reconstruct isotropic images free of artifacts, especially radial elongation. We measure the DOI by taking the ratio of the signals received by photodetectors in front and at the back of the scintillation crystals in the detector modules [2]. The DOI is measured in discrete fractions of the length of the crystals, modeling the crystals as being subdivided into 8 smaller crystals or DOI "bins.…”