Patient Position Lowers CT Radiation Dose

Centering a patient properly on the CT scan table can cut radiation dose up to 56 percent, but most patients are off-center, say U.S. researchers.

When patients are centered appropriately, their radiation doses are reduced between 7 and 29.9 percent for chest CT exams, and from 5.5 to 56 percent for abdominal CT scans, said researcher Mannudeep Kaira, who led a small study at Massachusetts General Hospital involving 63 patients.

In the study, radiology technologists placed the patients according to standard department protocol and their positions were checked by X-ray. When these positions were compared to the center points found by a laser centering system, 42 of the 45 abdominal CT patients were from 5.5 to 56 mm off-center and all the chest CT patients were improperly placed by 5.5 to 64 mm.

This study emphasizes that radiologists and technologists must pay close attention to patient centering, said Kaira. In addition, vendors are encouraged to develop and assess techniques that aid the technologist in accurate patient centering.

A report on the study appeared in the February issue of the American Journal of Roentgenology.