The research conducted by the Medical Physics Division (G. Donald Frey, Ph.D, Walter Huda, PhD, and Eugene Mah, M.S.) addresses three key issues pertaining to the use of ionizing radiations when creating medical images: (a) how much radiation do patients receive?; (b) what do such radiation exposures mean?; and (c) how can patient doses be reduced without adversely impacting on diagnostic performance?

Quantifying doses. We measure the radiation doses delivered to patient by use of anthropomorphic phantoms as shown in the figure. We are especially interested in quantifying the radiation doses delivered to pediatric patients.

Anthropomorphic phantoms used to measure patient doses

Interpreting doses. Medical radiation exposure in the US has increased by over 600% over the last 25 years. One of the most important reasons for this increase is the increasing utilization of CT imaging, a relatively high imaging modality. Our research work relates to quantifying the radiation risks, as well as their uncertainties. Our goal is to quantify any patient detriment from radiation exposure to balance against the benefit that most patients receive from the information obtained from radiological examinations.

Mathematical Phantoms used to calculate patient doses

Minimizing doses. The amount of radiation that is used to perform any radiological examination affects both the patient dose and the resultant image quality. A key issue facing radiologists is deciding how much radiation is really needed to get a satisfactory diagnosis. We have applied a new method which can quantify observer performance in any imaging method called Alternate Forced Choice (see figure). Using this tool, we can quantify how changes in the amount of radiation used will affect a radiologist’s ability to detect pathological lesions.

Alternate Forced Choice (AFC) method measures observer performance in CT