Compact Gamma Camera Developed for Prostate Cancer Imaging

defense laboratory and a Canadian company are developing a compact gamma camera for high-resolution imaging of prostate cancer. The camera system is a nuclear medical device that can localize cancer tissue in the prostate gland in detail at an early stage, which is important for the successful diagnosis and early treatment of the potentially lethal disease.

The common way to diagnose prostate cancer--the second leading cancer among men, next to lung cancer--is through a blood test that measures the levels of a protein produced by the prostate gland called prostate-specific antigen (PSA). Elevated PSA levels may indicate prostate cancer, but with a high number of false-positive detections. Frequently, then, men must have an invasive biopsy, usually guided by ultrasound imagery. Other methods for confirming a diagnosis of prostate cancer include traditional nuclear medical imaging techniques, such as positron emission spectroscopy and single photon emission computed tomography.

However, current imaging methods have limitations. Benign and cancerous tumors cannot easily be differentiated by ultrasound, and fibrous tissues can be mistakenly identified as tumors if patients have previously had radiation treatment of the prostate. Conventional nuclear imaging systems produce lower-resolution images, and are less efficient than the U.S. Department of Energy's Brookhaven National Laboratory's (Upton, NY, USA) compact digital camera. Moreover, the detectors in current systems are too large to be used in transrectal probes.

In contrast, the new cadmium zinc telluride (CZT)-based gamma camera is small enough for transrectal prostate-cancer diagnosis, after the patient is injected with a tracer radiopharmaceutical. The high-resolution CZT detector is the cutting-edge technology that drives the system. Using this new technology, the working distance between the imaging system and the prostate gland is minimized, allowing urologists to capture better images with a smaller amount of injected radioactive tracer, compared to conventional nuclear medical systems.

"This project has been a great opportunity to take gamma-ray detector technology originally developed for national security and apply it toward important societal goals in the area of cancer diagnosis and treatment,” said Dr. Ralph James, a senior physicist at Brookhaven who is the Laboratory's lead coinventor of the technology together with Brookhaven associate scientist Dr. Yonggang Cui.

Dr. Cui added, "The CZT material combines the best aspects of conventional nuclear imaging detectors while minimizing their weaknesses. Our experience in detector development and electronics design has been critical in delivering this high performance system in a very compact package at a competitive cost.”

Although the CZT-based system was designed to reveal prostate cancer, it can be modified for imaging other cancers, such as cervical, uterine, colorectal, and breast cancers. It can also be optimized for surgical use as a probe to guide the removal of cancerous tumors while minimizing damage to surrounding healthy tissues.

CZT detectors have advanced the development of new instruments for measuring radiation. Numerous medical, industrial, scientific, environmental, and homeland-security applications exist for this technology, including handheld instruments to reduce the trafficking of nuclear materials and portable field instruments for environmental monitoring and remediation.

The U.S. Department of Energy's (DOE) Office of Nonproliferation Research and Development has been the principal sponsor funding the development of CZT detectors, and Hybridyne Imaging Technologies (Toronto, ON, Canada) funded the design and engineering of the new compact gamma camera. The inventors have 16 patents on the technology, ranging from detector design and fabrication to imaging. Brookhaven Science Associates, the company that manages Brookhaven Lab, has a patent pending on the advanced CZT detectors.

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Brookhaven National Laboratory