Getting a read on radiation dose

Dose reduction is always a prominent topic in medical imaging, but this week’s top stories were especially dialed in on dose.

One important aspect of discussing dose that has become more prominent in recent years, and is a common thread woven throughout the dose stories on Health Imaging this week, is putting dose in context. Imaging is extremely useful for patient care because of the information it produces, and dose risks are outweighed by the benefits as long as a scan is ordered and performed appropriately.

With this in mind, radiation doses need not necessarily be feared, but unawareness should; that was the message of a European Society of Cardiology position paper urging cardiologists to better understand and minimize exposure. The authors stressed the importance for the specialty, as cardiologists are responsible for about 40 percent of the entire cumulative dose of medical radiation given to U.S. patients, excluding radiotherapy.

A study published in the American Journal of Roentgenology also put dose in context by examining the effect CT scans for severe traumatic brain injuries (TBIs) have on lifetime attributable risk of cancer and cancer-related mortality.

Included in the study were 67 patients, at least 16 years old, who were admitted to a level one trauma center from 2007 to 2010 for a severe TBI. In the first year after the injury, the median number of CTs received by each patient was 20.

Results showed that the average cumulative effective dose was 87 mSv, which represents an increased lifetime incidence of all cancer types from 45.5 percent to 46.3 percent. This translates to negligible increase in lifetime incidence of cancer-related mortality from 22.1 percent to 22.5 percent. A total of 183 patients with severe TBI would have to receive similar doses before one would contract an attributable cancer.

While sensationalism of dose risks is not beneficial, clearly there are still some associated risks of imaging, which is why it is so important to continue striving for effective dose reduction. Another of the week’s top stories highlighted this type of research, as a study published in Radiology demonstrated that 40 percent adaptive statistical iterative reconstruction (ASIR) could reduce the relative dose for chest CT by an average of 39 percent. The average dose reduction for abdominopelvic CT with the ASIR technique was 29 percent.

What has your practice done to reduce and track doses absorbed by patients?

Evan Godt
Editor – Health Imaging