Patients, Docs Unaware of CT Radiation Dose

How much radiation do you get from a CT scan? It’s substantially higher than most patients, and even their doctors, realize, according to a new report.

The radiation dose from one abdominal CT scan has been estimated to be equivalent to 100 to 250 chest X-rays, the authors explain in the May issue of Radiology. One controversial study has attributed 2500 deaths annually to CT examinations in the United States. Dr. Howard P. Forman and colleagues from Yale University in New Haven, Connecticut, surveyed patients, emergency department (ED) physicians, and radiologists to determine the awareness level concerning radiation dose and possible risks associated with CT scans. Only 5 of 76 patients (7 percent) reported being informed of the risks and benefits before their CT scan, the authors report, and only 10 of 45 ED physicians (22 percent) reported explaining those risks and benefits to their patients. Nearly half the radiologists (47 percent) believed that a CT scan increased the lifetime risk of cancer, the results indicate, but a similar belief was reported by only 3 percent of patients and 9 percent of ED physicians. Ninety-two percent of patients estimated the radiation dose of one CT scan to be no more than 10 chest X-rays, the researchers note, as did 51 percent of ED physicians and 61 percent of radiologists. Only 22 percent of ED physicians and 13 percent of radiologists (and none of the patients) had dose estimates in the accurate range. “Given the current debate about the possible increased cancer risk associated with diagnostic CT scans,” the investigators write, “we believe that it is important that the radiology community make current information regarding CT radiation dose more widely available.” Physicians are not adequately prepared to answer questions their patients should be asking about the risks and benefits of imaging studies, Forman told Reuters Health. “We must empower our patients to ask questions, and our physicians … must become better prepared to answer these important questions.” “Not all imaging is necessary and unnecessary imaging, with its attendant risk, is bad medicine,” Forman concluded. “On the other hand, I would not want to frighten patients from having necessary studies performed; they should be informed, though.” (SOURCE Radiology: Reuters Health News: Will Boggs, MD: May 2004.)