Radiation exposure from CT scans: how to close our knowledge gaps, monitor and safeguard exposure--proceedings and recommendations of the Radiation Dose Summit, sponsored by NIBIB, February 24-25, 2011

Abstract

This article summarizes the proceedings of a portion of the Radiation Dose Summit, which was organized by the National Institute of Biomedical Imaging and Bioengineering and held in Bethesda, Maryland, in February 2011. The current understandings of ways to optimize the benefit-risk ratio of computed tomography (CT) examinations are summarized and recommendations are made for priority areas of research to close existing gaps in our knowledge. The prospects of achieving a submillisievert effective dose CT examination routinely are assessed.

Figure 1:

The x-axis represents a patient size metric (effective diameter) and the y-axis represents the normalized dose coefficient for the 32 cm polymethyl methacrylate (PMMA) phantom. Note that AAPM Task Group 204 Report also contains conversions for 16 cm PMMA phantom as well. (Reprinted, with permission, from reference .)

Figure 2:

Left: In perfusion or interventional CT (where there is no table movement), the peak skin dose is the relevant dose parameter for deterministic skin effects. The peak skin dose equals the peak dose from one scan times the number of scans. Right: If the peripheral CTDI₁₀₀ is used as a surrogate for peak dose, the skin dose will be overestimated by up to a factor of two. (Reprinted, with permission, from reference .)