DOI Encoding on the PET Detector Using 2 X 2 PMT Array. IEEE Nucl. Sci. & Med. Imag.

A whole body positron emission tomography (PET) scanner is equipped with many detectors so that the detector should be cost effective. Some detectors utilizing low cost PMTs were developed on that purpose and we also have tried to develop a whole body PET detector with a 2 x 2 array of such PMT. For a PET scanner of high sensitivity with a large axial view, the detector is considered to have depth-of-interaction (DOI) encoding capability that avoid parallax error.On the detector composed of a 2 x 2 PMT array and an array of small scintillation crystals, a light guide is generally used to make scintillation light spread to identify the scintillated crystal by Anger-type calculation of the PMT signals. A new way we propose for crystal identification is removing some reflector between crystals and inserting reflector between the crystal array and PMTs to make the light spread and also control the light path. This new way can be used to design a new type of DOI detector with same kind of crystals.IEEE 2007 Nuclear Science Symposium and Medical Imaging Conferenc

Optimization of Crystal Arrangement on 8-Layer DOI PET Detector

Previously, we proposed an 8-layer depth-of- interaction (DOI)encoding method for a PET detector and proved its validity. The layer ofinteraction is identified by hybrid method; the scintillation light controlby the original reflector arrangement for 4-layer DOI encoding and the pulseshape discrimination for 2-layer DOI encoding. Four layers then consist ofthe scintillator of different pulse shape from the scintillator for theother four layers. We investigated the effect of crystal arrangement difference ondetector performance to optimize the DOI detector. The two kind layers canbe arranged in two ways; stacked alternately or set in the upper and lowerfour layers respectively. Since the two crystal arrangements are supposed toshow different detector performance, we measured it on each arrangement. Theresults show better performance of the stacked arrangement in pulse shapediscrimination, while inferior in crystal identification among the same kindscintillation crystals composing four layers. There was no particulardifference between the two crystal arrangements in light outputs and energyresolutions of each layer.IEEE 2006 Nuclear Science Symposium and Medical Imaging Conferenc

A DOI PET Detector With Scintillation Crystals Cut in Triangular Prism

We propose a new depth of interaction (DOI) detector which is made of scintillation crystals cut in triangular prism. Preliminary study was carried out with Lu2xGd2(1-x)SiO5 (LGSO) crystals cut in three-square of 3.0 mm and 10.0 mm long. They are arranged in 3-layer DOI array and coupled to a position sensitive photomultiplier tube (PS-PMT). By removing some reflector from the crystal array to control scintillation light spread, we could obtain the 2-dimensional position histogram in which responses of the crystals in all layers are discriminated with only Anger-type calculation of the PS-PMT signals.2008 Nuclear Science Symposium, Medical Imaging Conferenc

PET detector with scintillation crystals cut in triangular prism

We propose a new depth of interaction (DOI) detector which is made of scintillation crystals cut in triangular prism. Preliminary study was carried out with Lu2xGd2(1-x)SiO5 (LGSO) crystals cut in three-square of 3.0 mm and 10.0 mm long. They are arranged in 3-layer DOI array and coupled to a position sensitive photomultiplier tube (PS-PMT). By removing some reflector from the crystal array to control scintillation light spread, we could obtain the 2-dimensional position histogram in which responses of the crystals in all layers are discriminated with only Anger-type calculation of the PS-PMT signals.2008 Nuclear Science Symposium, Medical Imaging Conferenc

Crystal identification performance of the jPET detector depending on refractive index of optical cement between scintillators

2008 Nuclear Science Symposium, Medical Imaging Conferenc

Crystal identification performance of the jPET detector depending on refractive index of optical cement between scintillators

2008 Nuclear Science Symposium, Medical Imaging Conferenc

Spatial resolution evaluation with a pair of two four-layer DOI detectors for small animal PET scanner: jPET-RD

We are developing a small animal PET scanner, "jPET-RD" to achieve high sensitivity as well as high spatial resolution by using four-layer depth-of-interaction (DOI) detectors. The jPET-RD is designed with two detector rings. Each detector ring is composed of six DOI detectors arranged hexagonally. The diameter of the field-of-view (FOV) is 8.8 cm, which is smaller than typical small animal PET scanners on the market now. Each detector module consists of a crystal block and a 256-channel flat panel position-sensitive photomultiplier tube. The crystal block, consisting of 32 x 32 x 4 crystal (4096 crystals, each 1.46 mm x 1.46 mm x 4.5 mm) and a reflector, is mounted on the 256ch FP-PMT.\nIn this study, we evaluated the spatial resolution of reconstructed images with the evaluation system of two four-layer DOI detectors which consist of 32 x 32 x 4 LYSO (Lu: 98%, Y: 2%) crystals coupled on the 256ch FP-PMT by using RTV rubber. The spatial resolution of 1.5 mm was obtained at the center of the FOV by the filtered back projection. The spatial resolution, better than 2 mm in the whole FOV, was also achieved with DOI while the spatial resolution without DOI was degraded to 3.3 mm