Rensselaer nabs grant to track CT rad exposure

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The National Institutes of Health (NIH) have awarded researchers from Rensselaer Polytechnic Institute in Troy, N.Y., a $1.2 million grant to develop software and patient-specific virtual phantoms to calculate and track patient radiation exposure from CT imaging.

Funded by the NIH's National Institute of Biomedical Imaging and Bioengineering (NIBIB), the software aims to arm radiologists, medical physicists and patients with more accurate data for making informed decisions about the potential risks and benefits of CT exams.

This plays into a larger goal of governmental agencies and hospitals of reducing the number of unnecessary CT scans performed in the U.S. and globally, said project leader X. George Xu, PhD, a Rensselaer professor.

“Radiation exposure from imaging procedures such as CT scans has elevated to an alarming level in the U.S. and elsewhere in recent years,” said Xu, a nuclear engineering professor in the department of mechanical, aerospace and nuclear engineering at Rensselaer.

“The radiation exposure from a single CT scan is still relatively small when compared with the clinical benefit of the procedure, but patients often receive multiple scans during the course of their diagnostic or therapeutic procedure. Our new software should help to record the exposures more accurately and more consistently.”

A recent report by the National Council on Radiation Protection and Measurements (NCRP), of which Xu is a member, details how the U.S. population is now exposed to seven times more radiation every year from medical imaging exams than it was in 1980. While CT scans only account for 10 percent of diagnostic radiological exams, the procedure contributes disproportionately—about 67 percent—to the collective medical radiation exposure across the U.S.

To help mitigate this risk, several national and international bodies have called for the establishment of a centralized, patient-specific dose registry system. Such a system would track the amount of CT scans a patient undergoes over time, and the radiation exposure resulting from those procedures. However, current software packages for tracking CT scan radiation exposure have fundamental imitations and are insufficient for such a critical task, Xu said.

The new software that Xu and his team are developing, VirtualDose, takes into consideration a patient’s individual characteristics, including age, sex, pregnancy, height and weight. By entering these data into the software, the program creates a virtual 3D “phantom” closely matching with the patient. These anatomically realistic phantoms accurately model the patient’s internal organs, and detail how radiation interacts with each organ. The phantom, in turn, allows physicians and researchers to compare the levels of radiation exposure a patient gets from different CT protocols or different scanner designs.

Current software for CT radiation dose reporting uses outdated models of patients, and often lacks necessary software features, Xu said. This makes it nearly impossible to accurately track and record radiation exposure to organs from x-rays.

Xu said personalized virtual phantoms are particularly important for predicting radiation exposure from CT scans for the groups most sensitive to radiation—children and pregnant women. These groups are ignored by nearly all dose measurement software, he said.

Clinical testing of the software will take place at several hospitals, including Massachusetts General Hospital in Boston and Shands Hospital at the University of Florida in Gainesville.