In a survey of radiologists and technicians, researchers from the University of Saskatchewan in Canada found that most physicians recognized an increased risk of cancer from CT but underestimated the actual ionizing radiation dose to a patient.

The team set out to assess a health care professional’s knowledge of radiation dose by conducting a survey that was predominately multiple choice. A total of 308 health care providers completed the survey, including 217 referring physicians, 32 radiologists and 59 technologists.

Results from the survey showed that 73 percent of physicians, 97 percent of radiologists and 76 percent of technologists know that there is an increased risk of cancer from an abdominal-pelvic CT but only 18 percent of physicians, 28 percent of radiologists and 22 percent of technologists correctly identified the dose of the abdominal-pelvic CT compared to chest X-rays.
Forty eight percent of physicians, 78 percent of radiologists and 63 percent of technologists had accurately estimated or overestimated the radiation dose of abdominal-pelvic CT compared to a chest X-ray — but it was those who underestimated the dose who worry the researchers.

“To our knowledge we were the first investigators to evaluate knowledge of CT dose levels and risks amongst healthcare providers who routinely use CT versus those who don’t. We were reassured to see better knowledge amongst those who use CT than those who don’t,” lead investigator Dr. David Leswick, FRCPC, Department of Medical Imaging, College of Medicine, University of Saskatchewan, told HCB News.

“Underestimating radiation dose from a CT scan is more concerning than knowing the exact dose level, particularly when it is a vast underestimation, as this may lead to minimization of the risk estimate when considering a test,” he said.

A chest X-ray is .02 to .2 millisieverts (mSv) while an average radiation dose from an abdominal-pelvic CT is 10 mSv, making the ionizing radiation from the CT scan 100 to 250 times more than that of a chest X-ray.

The researchers also discovered that the participants had confusion regarding radiation exposure from MR and ultrasound. Both these scanning techniques do not use radiation but 20 percent of physicians, 6 percent of radiologists and 7 percent of technologists believed MR used radiation, and 11 percent of physicians, no radiologists, and 7 percent of technologists believed ultrasound used radiation.

Leswick said that these beliefs are troubling because it may lead to underutilization of an MR or ultrasound due to “unfounded radiation concerns.”

The researchers’ results showed that 93 percent of the survey participants would be interested in receiving radiation dose feedback when considering ordering a CT scan.

“It is important for health care professionals (including referring physicians, radiologists, and technologists) to be aware of radiation dose levels and risks from imaging tests for several reasons, including the ability to weigh the risks and benefits of tests, counsel patients on relevant risks, optimize protocols to minimize radiation dose, and select appropriate protocols to minimize radiation dose,” said Leswick.

X-Ray Homepage