IEEE Transactions on Nuclear Science

Scintillating films are usually used to improve the sensitivity of CCD-based X-ray imaging detectors. For an optimal spatial resolution and detection efficiency, a tradeoff has to be made on the film thickness. However, these scintillating layers can also be structured to provide a pixellated screen. In this paper, the study of CsI(Tl)-filled pore arrays is reported. The pores are first etched in ... View full abstract»

We describe the development of a scintillator-coated charge coupled device (CCD) based camera for imaging small volumes of radionuclide uptake in tissues. The high-resolution gamma imager (HRGI) is a collimated, scintillator-coated, low cost, imager using low noise CCDs. The HRGI operates in photon counting mode using a peltier cooler to achieve an operating temperature of -5°C. We have measur... View full abstract»

We have developed Lu$_0.4$Gd$_1.6$SiO$_5$:Ce (LGSO) crystals as a new scintillator for medical applications. Scintillation properties of LGSO crystal of various Ce concentrations and their dependence on annealing effect were studied. Its absorption coefficient at 511 KeV gamma rays is 0.70 cm$^-1$. We observed that the light output and decay time are dep... View full abstract»

High spatial resolution is essential to image small lesions in positron emission tomography. Traditional methods suggest using small crystals to obtain high resolution. In this study, a new method is introduced to achieve high spatial resolution by using scintillators with different decay times arranged in a checkerboard pattern. Pulse shape discrimination was implemented to determine which crysta... View full abstract»

This paper describes the LSO/LuYAP phoswich detector head developed for the ClearPET small animal PET scanner demonstrator that is under construction in Lausanne within the Crystal Clear Collaboration. The detector head consists of a dual layer of 8×8 LSO and LuYAP crystal arrays coupled to a multi-anode photomultiplier tube (Hamamatsu R7600-M64). Equalistion of the LSO/LuYAP light collectio... View full abstract»

We found that Bi4Ge3 O12 (BGO) scintillator can be elements of a four-layer depth of interaction (DOI) detector and it was proved with a 12×12×4 array of BGO crystals in dimensions of 2.9 mm×2.9 mm×7.5 mm coupled to a 256-channel flat panel position sensitive photomultiplier tube. Appropriate reflector insertion in the array makes all crysta... View full abstract»

Previously, we proposed a new depth of interaction (DOI) encoding method and proved that it worked successfully with four-layered Gd2SiO5 crystals for a small animal positron emission tomography (PET) detector. We are now planning to develop a small animal PET scanner, jPET-RD (for rodents with DOI detectors), which has both high resolution and high sensitivity by the use of ... View full abstract»

GSO position-sensitive block detectors have been developed using the PMT-Quadrant -Sharing (PQS) technology for animal PET imaging. Two prototype block detectors with dimensions of 1.51 mm×1.51 mm×10 mm (12×12 array) and 1.66 mm×1.66 mm×10 mm (11×11 array) were built using 19 mm round PMTs. The Enhanced Specular Reflector mirror-film (98% reflectance, 0.065 mm t... View full abstract»

We propose and test a one-dimensional (1-D) sharing block detector using dual photo-multiplier tubes (PMT). The detector consists of scintillator blocks and dual PMTs. The dual PMTs are optically coupled on the scintillator blocks and overlap in one dimensional. With this configuration, the scintillator size of the block detector can be reduced to half that of a conventional block detector in one ... View full abstract»

To improve the spatial resolution of a small field-of-view gamma camera composed of a NaI(Tl) scintillator and a position sensitive photo-multiplier tube (PSPMT), the performance of an NaI(Tl) scintillator with a fiber optic plate for a light output was compared with that of such a scintillator using a conventional glass plate. Since the fiber optic plate limits the light distribution and makes it... View full abstract»

We are investigating the use of a CCD for high-resolution radionuclide imaging. The use of a CCD has the potential to provide very high spatial resolution on the order of 200 to 400 μm, while significantly simplifying the readout electronics. The detector is based on a special CCD with on-chip multiplication gain that allows high-speed operation while maintaining the read noise at a very low le... View full abstract»

A compact detector, sized particularly for imaging a mouse, is described. The active area of the detector is approximately 46 mm × 96 mm. Two flat-panel Hamamatsu H8500 position-sensitive photomultiplier tubes (PSPMTs) are coupled to a pixellated NaI(Tl) scintillator which views the animal through a copper-beryllium (CuBe) parallel-hole collimator specially designed for 125I. Alth... View full abstract»

Our group is developing a scanner that combines x-ray, single gamma, and optical imaging on the same rotating gantry. Two functional modalities (SPECT and optical) are included because they have different strengths and weaknesses in terms of spatial and temporal decay lengths in the context of in vivo imaging, and because of the recent advent of multiple reporter gene constructs. The effect of att... View full abstract»

The design and evaluation of the imaging system Clear-PEM for positron emission mammography, under development by the PEM Consortium within the framework of the Crystal Clear Collaboration at CERN, is presented. The proposed apparatus is based on fast, segmented, high atomic number radiation sensors with depth-of-interaction measurement capabilities, and state-of-the-art data acquisition technique... View full abstract»

The CPS Accel is a commercial PET camera based on a block detector with 64 LSO scintillator crystals (each 6.75×6.75×25 mm) read out with 4 photomultiplier tubes. The excellent timing resolution of LSO suggests that this camera might be used for time-of-flight (TOF) PET, thereby reducing the statistical noise significantly. Although the Accel achieves 3 ns coincidence resolution (a fac... View full abstract»

Aim of this work was the implementation and validation, for the Discovery-ST PET/CT (GE Medical Systems) system, of the acquisition-specific noise equivalent counts (AS-NEC) method to establish the amount of tracer to be injected in 3D$^18$F-FDG whole body (WB) PET studies to achieve the peak of the NEC (NEC-p) at the acquisition time. The AS-NEC method uses prompts, delayed events and ... View full abstract»

Methods to test the practical performance of the Philips Gemini PET/CT system during clinical imaging are described and results presented. The test methods used were based on the NEMA standards and those suggested by a task group of the Commission of European Communities (EEC). These were performed using the EEC emission phantom, and phantoms provided by Philips. Scans were acquired using the rout... View full abstract»

The use of x-ray computed tomography (CT)-based attenuation correction for positron emission tomography (PET) in PET/CT systems requires the transformation of CT Hounsfield units (HU) to linear attenuation coefficients at 511 keV (LAC511). This cannot be done perfectly from a single peak kilovolt (kVp) CT scan due to variability in Compton and photoelectric composition and, thus, an app... View full abstract»

Daily quality assurance of positron emission tomography detectors, to ensure accurate efficiency calibration of the system, typically requires the acquisition of coincidence data from a flood source. To obtain sufficient counts, long scan times on the order of an hour are required. The long acquisition time and necessity of an external activity source may make such a protocol impractical for daily... View full abstract»

Pinhole collimation is used as a magnifying geometry to overcome the resolution constraints of the gamma cameras used in SPECT. It is very sensitive to the mechanical position of the aperture relative to the axis of rotation. It is also sensitive to the axial position of the aperture. When one camera head is used, there is no intrinsic reference point for determining the axial mechanical shift. Ho... View full abstract»

We are developing a positron emission tomography (PET) system dedicated to breast cancer imaging and based on a pseudo-pinhole PET geometry. The system consists of a small half-ring (r=153 mm) of high-resolution LSO detectors and a large half-ring (R=413 mm) of medium-resolution LSO detectors. The coincidence detection profile between a small LSO crystal and a large LSO crystal reveals that, when ... View full abstract»

The goal of this study was to evaluate the magnitude and origin of scattered radiation in a small-animal PET scanner and to assess the impact of these findings on noise equivalent count rate (NECR) measurements, a metric often used to optimize scanner acquisition parameters and to compare one scanner with another. The scatter fraction (SF) was measured for line sources in air and line sources plac... View full abstract»