CT Radiation Dosing: Where Things Stand, Part 2

Recently published research revealed significant declines in radiation dosing levels for common computed tomography (CT) exams over the course of a decade. In addition to a 31.2 percent decrease in radiation dosing for contrast-enhanced chest CTs, a 15 percent reduction in dosing for contrast-enhanced neck CTs and a 25 percent dosing decrease for non-contrast cervical spine CTs, the study authors noted an overall 21.8 percent decrease in diagnostic reference levels (DRLs) for CT exams.

In the second part of a two-part interview, lead study author Kalpana Kanal, PhD, and co-author Mahadevappa Mahesh, MS, noted the approximately six-month turnaround time for publishing the 2025 study data in comparison to a three-year turnaround time for a previous similar study on 2014 data published in 2017. They both emphasized the importance of capturing acquisition-level data to capture as close to a dynamic real-time picture as possible of CT DRLs.

“We are trying to template (this so) DRLs can be published on a short period of basis within a year (or) within six months. That is the idea because DRL is not a one-time done deal. It has to be looked at over a period of time so you can correct yourself, not with the aim of going down, but to see what's being practiced and how (it) can be tightened up,” explained Dr. Mahesh, a professor of radiology and cardiology at the Johns Hopkins School of University School of Medicine.

In regard to follow-up research, Dr. Mahesh is currently working on a cardiac CT DRL study that he plans to speak about at the upcoming RSNA conference in November. Dr. Kanal said a forthcoming study publication will focus on CT DRLs for pediatric patients.

Emphasizing that indication-based DRLs are very common in Europe, Dr. Kanal said this needs to be a research priority in the United States.

“I think we need to start moving towards indication-based data because it depends on your clinical indication how much dose you need. … Is it a subtle diagnosis you're looking for or is it something very obvious that will impact how much dose you're using. That will give you different DRL values,” posited Dr. Kanal, a professor of radiology at the University of Washington in Seattle.