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In this paper, we discuss the design of a compact gamma camera for high-resolution prostate cancer imaging using
Cadmium Zinc Telluride (CdZnTe or CZT) radiation detectors. Prostate cancer is a common disease in men.
Nowadays, a blood test measuring the level of prostate specific antigen (PSA) is widely used for screening for the
disease in males over 50, followed by (ultrasound) imaging-guided biopsy. However, PSA tests have a high falsepositive
rate and ultrasound-guided biopsy has a high likelihood of missing small cancerous tissues. Commercial
methods of nuclear medical imaging, e.g. PET and SPECT, can functionally image the organs, and potentially find
cancer tissues at early stages, but their applications in diagnosing prostate cancer has been limited by the smallness of
the prostate gland and the long working distance between the organ and the detectors comprising these imaging systems.
CZT is a semiconductor material with wide band-gap and relatively high electron mobility, and thus can operate at room
temperature without additional cooling. CZT detectors are photon-electron direct-conversion devices, thus offering high
energy-resolution in detecting gamma rays, enabling energy-resolved imaging, and reducing the background of
Compton-scattering events. In addition, CZT material has high stopping power for gamma rays; for medical imaging, a
few-mm-thick CZT material provides adequate detection efficiency for many SPECT radiotracers. Because of these
advantages, CZT detectors are becoming popular for several SPECT medical-imaging applications.
Most recently, we designed a compact gamma camera using CZT detectors coupled to an application-specific-integratedcircuit
(ASIC). This camera functions as a trans-rectal probe to image the prostate gland from a distance of only 1-5 cm,
thus offering higher detection efficiency and higher spatial resolution. Hence, it potentially can detect prostate cancers at
their early stages. The performance tests of this camera have been completed. The results show better than 6-mm
resolution at a distance of 1 cm. Details of the test results are discussed in this paper.
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