Development of Semiconductor Gamma-Camera System with CdZnTe Detectors

Abstract

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.

Study of a New Design of P-N Semiconductor Detector Array for Nuclear Medicine Imaging by Monte Carlo Simulation Codes

“…Since introducing gamma camera on 1964, it has improved greatly in all aspects such as spatial and energy resolution, uniformity, field of view, and type of detectors. [1] These improvements made it as a suitable choice for a variety range of clinical studies. Important parts of a gamma camera are collimator, sodium iodide crystal, optical channels, and photomultiplier tubes.…”

“…[3] Some researcher used arrays of CdZnTe semiconductor gamma-ray detectors[45] and improved the energy resolution to 6% and spatial resolution to 6.2 mm in gamma camera. [1] Others have used different electrode configuration of planar[6] and coplanar electrode[7] as a charge sensing detectors.…”

Development of an ultra-high resolution SPECT system with a CdTe semiconductor detector

“…To cope with this resolution issue [3], small animal SPECT systems with pinhole collimators have been proposed [4][5][6][7] and lack of the intrinsic spatial resolution of the scintillation detector was compensated for with the geometrical magnification effect of the pinhole collimator. Another strategy to improve the spatial resolution of the small animal SPECT system is utilization of pixelated detectors such as discrete NaI(Tl) or CsI(Tl) crystals [8][9][10][11][12][13] or cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe) semiconductor detectors [14][15][16][17][18][19][20][21][22][23], which are used with a parallel-hole collimator or pinhole collimator. The pixelated nature of these detectors is expected to greatly improve the spatial resolution when we use very small pixels in a detector at the sacrifice of the detection efficiency.…”