The Clinical Center at the National Institutes of Health (NIH) in Maryland, has begun investigating the potential of a photon-counting detector (PCD) CT scanner in a hospital-based research setting.

Unlike conventional CT scanners, which utilize energy-integrating detectors (EIDs) to create an electrical signal using X-rays, PCDs calculate individual photon interactions through high-speed semiconductors, eliminating reliance on resolution-limiting scintillator crystals.

The prototype technology — which only three facilities, including the Clinical Center, are currently using — is expected to yield comparable image quality to conventional CT while also providing an enhanced look inside the body through multi-energy imaging.

So far, over 45 volunteers enrolled in an abdominal research protocol have reportedly benefited from the technology, with initial findings published in the journal Radiology.

Their results showed that both types of systems displayed similar performance in all the categories studied, with PCD improving iodine mapping capabilities as compared to EID scans.

Although the performance of PCD showed no statistically significant difference compared with EID when the abdomen was evaluated in a conventional scan mode, PCD provides spectral information, which may be used for material decomposition. The researchers ultimately hope to improve the diagnosis that doctors can offer by increasing the resolution and contrasts available for analysis.

"Now is an exciting time for us and for our study participants here in the Clinical Center as we help test and develop this CT technology so that it may one day help patients around the world and impact the health care they receive," said Dr. David Bluemke, chief of the Department of Radiology at the NIH Clinical Center, in a statement.

Over the next five years, he and his team plan to develop scan protocols and image processing algorithms with the goal of improving screening, imaging, and treatment planning for cancer and cardiovascular disease.

Researchers hope that by increasing the resolution and contrasts available for analysis, physicians will be able improve the diagnostic value of the imaging exam. The NIH Clinical Center has outlined three areas where photon CT may yield extra diagnostic value:

• Doctors can identify materials in the body with anatomic precision. A dye, or contrast, is often given to a patient so that researchers can see a selected area in more detail. Different materials in the body can be displayed in different colors for faster diagnosis and precision.


• The new technology may be used to help identify and characterize tumors, plaques, or vessels that are smaller than half a millimeter. For many patients, finding a tumor that size may make a difference in identifying if it is benign or could be cancerous.


• The technology may help to more accurately identify soft tissues such as proteins, tendons or collagen which are hard to differentiate with current equipment.

As cutting edge as photon counting CT scanners are, they have been a research topic for several years. In the November 2011 edition of GE Healthcare's CT Clarity magazine, Dr. Tibor Duliskovich said the technology counts individual X-ray photons hitting the surface of a single photosite of the detector — "essentially, detecting individual events on a nanosecond scale."

Through a cooperative research and development agreement with the manufacturer, Siemens Healthcare, and other researchers, the NIH is hoping to optimize the usage of photon-counting detector CT so it can someday benefit patients around the globe.