More careful 'aiming' of CT cuts down on radiation without compromising image quality

May 01, 2006

In most cases, longer localizer radiographs and the extra images acquired at abdominal or pelvic CT do not contribute additional diagnostic information, according to a new study by researchers from Emory University Hospital in Atlanta, GA.

For this ongoing study of 200 patients, 50 consecutive abdomen-pelvic CT studies were reviewed to determine how much the longer localizer radiographs and extra axial images went beyond defined levels. The researchers found that localizer radiographs were extended above the diaphragm and below the symphysis pubis in 96% and 72% of the examinations, respectively. Extra images were acquired above the dome of the diaphragm in 94% and below the pubic symphysis in 90% of the examinations, respectively. All in all, the researchers found that a total of 562 extra images were acquired in the 50 examinations.

According to the researchers, scanning beyond the region of interest is a common problem in most head, neck and body CT studies. "When other scanning parameters are kept constant, the radiation dose is directly proportional to the scan volume, so limiting the region of scanning will be a practical way of reducing radiation dose in all CT studies," said S. Namasivayam, MD, lead author of the study.

"There is a widespread awareness of radiation risk from CT, and doctors are trying to find ways to cut down on that risk. The results of our study show that limiting the length of scanning for the body part under study can reduce the radiation dose, while still maintaining the diagnostic quality of the CT study," said Dr. Namasivayam.

The full results of the study will be presented on Monday, May 1, 2006 during the American Roentgen Ray Society Annual Meeting in Vancouver, BC.
About ARRS
The American Roentgen Ray Society (ARRS) was founded in 1900 and is the oldest radiology society in the U.S Radiologists from all over the world attend the ARRS Annual Meeting to take part in instructional courses, scientific paper presentations, symposiums, new issues forums and scientific and commercial exhibits related to the field of radiology. The ARRS is named after Wilhelm Röentgen, who discovered the x-ray in 1895.

American College of Radiology

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