Au(evaporated film) -semiconductor(substrate) systems were studied by Auger electron spectroscopy. For semiconductors with energy gaps (Eg) smaller than ∼2.5 eV, even at room temperature a considerable fraction of atoms constituting the semiconductors were found to accumulate on the surfaces of Au films, indicating ready interfacial interaction between these materials. Study of the interface regions of the above systems verified the occurrence of the room-temperature interfacial reactions.
A CdZnTe semiconductor detector, which works at room temperature, may realize a next generation gammacamera system due to its high spatial resolution and high energy resolution. We made a prototype gamma-camera system with CdZnTe detectors to evaluate the feasibility of the semiconductor gamma-camera. This paper described our prototype system and some results obtained with this system.
I. INTRODUCTIONHE CdZnTe semiconductor detector[1]- [4], which works at room temperature, is one alternative to the conventional gamma-ray detector such as an NaI scintillator. This semiconductor detector is superior to the NaI scintillation detector in its energy resolution and spatial resolution. The energy resolution of the semiconductor detector such as CdZnTe is about 6% FWHM at 140 keV, while the energy resolution of the NaI scintillator is about 9% FWHM at 140 keV. In the semiconductor detector, measurement of photons is performed pixel by pixel with a small electrode, so that the spatial resolution of measured data becomes almost the same as the size of a detection unit (pixel). Thus the spatial resolution can be as small as 1×1mm 2 . In addition, the detection of gamma rays is conducted with pixel-base so that the contrast resolution will improve compared with the conventional gamma camera system. These features of the semiconductor detector enable us to reconstruct a high quality SPECT image. Some researches have been conducted with this detector aiming at the high spatial resolution in small animal imaging[5]- [9]. And if we appropriately design a semiconductor gammacamera system, we can obtain physiological information with higher resolution than that obtained with a clinical PET system. With this purpose in mind we made a prototype gamma-camera system with CdZnTe semiconductor detectors. This paper outlines the details of our system and the performance of the detector and the SPECT system.
We made a prototype gamma camera system with CdZnTe semiconductor detectors that work at room temperature. The effective field of view of this detector is 195 × 156 mm 2 with a pixel size of 2.46 × 2.46 mm 2 . We evaluated the performance of the detector in terms of the energy resolution, intrinsic spatial resolution, system spatial resolution and system sensitivity. The performance of the detector was evaluated with methods based on the NEMA standard (NU1). The results showed that the mean energy resolution was 5.55 % FWHM for 99m Tc, the intrinsic spatial resolution 2.46 mm FWHM, the system spatial resolutions 7.1 mm FWHM (without scatterer) and 7.4 mm FWHM (with scatterer), and the system sensitivity 46.3 cps/MBq. The performance of the system was also evaluated with some SPECT phantoms and the feasibility of the detector was confirmed with the SPECT images.
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