New protocol screens clinical research participants for prior radiation exposure

A new study highlights a critical gap: most clinical research studies that use imaging techniques such as amyloid positron emission tomography (PET) scans do not account for the radiation participants have already received from prior medical procedures. As brain imaging technology becomes more widely used in medical research - especially following recent U.S. Food and Drug Administration approvals of new Alzheimer's treatments - questions are emerging about how much radiation research participants are accumulating over a lifetime of medical scans. While radiation exposure from PET imaging is generally considered acceptable when used in direct patient care, the risks are less clear-cut when exposure occurs solely for research purposes, particularly when participants may not directly benefit. The researchers developed and tested a systematic screening protocol to address this gap - and found it made a meaningful difference in protecting participant safety.

Published in the Ochsner Journal, the study "Development and Implementation of a Radiation Safety Screening Protocol for a Clinical Study Using Amyloid Positron Emission Tomography Imaging" reviewed 92 clinical research studies listed on ClinicalTrials.gov that included amyloid PET imaging. Researchers found that only 1% of these studies provided specific radiation exposure thresholds as exclusion criteria, and 37% reported no screening for prior radiation exposure at all.

To fill this gap, the team developed a radiation safety screening protocol and implemented it in the Successful Aging after Elective Surgery (SAGES) study, a long-term research study examining adults aged 70 and above. When the screening procedure was applied to 101 prospective research participants, 17% - nearly 1 in 5 - were found to have received enough prior radiation to be deemed ineligible for the amyloid PET component of the study. Because older adults often accumulate radiation from years of diagnostic imaging, their total lifetime dose may exceed safe thresholds for additional elective research-related exposure - a factor that research investigators have not been systematically accounting for.

Imaging with exposure to ionizing radiation has become increasingly common for both clinical and research applications. When used for research purposes, the risks of additional exposure to radiation need to be carefully considered, particularly for research studies that may not directly benefit the participant. To assess risk for participation in an imaging study, we developed and implemented a safety screening procedure to estimate prior radiation exposure and assure safe study participation. We propose that clinicians and researchers consider implementing a similar method for estimating prior radiation exposure to enhance research participant safety."

Tamara G. Fong, MD, PhD, study's lead author, Associate Scientist, the Hinda and Arthur Marcus Institute for Aging Research, Hebrew SeniorLife

The authors call for a standardized approach to tracking cumulative radiation exposure across a lifetime, ensuring that research participants - especially older adults who may have had many diagnostic scans over the years - are not unknowingly placed at increased risk when volunteering for research that may not directly benefit them. By developing and sharing their screening protocol through the SAGES study, the researchers provide a practical, replicable model that other investigators can adapt for their own research studies.

This research was supported by the National Institute on Aging under project grants P01AG031720 and R33AG071744.