Flaw in Radiation Reduction Efforts, One Size Doesn’t Fit All

“One-size-fits-all” radiation reduction protocols may be misleading, according to a recently published study, because patients receiving the least benefit of the dose reductions may contribute disproportionately toward improved averages.

“Put another way, tailoring dose-reduction efforts to preferentially affect younger healthier patients, thus allowing elderly patients or patients with low life expectancy the benefits in image quality that may be afforded by higher radiation doses, may compromise an institution’s performance metrics, even though their efforts may be appropriately patient centered,” wrote Jonathan D. Eisenberg, BA, of Massachusetts General Hospital, and colleagues. “Our findings emphasize the need to consider more granular patient-centered benchmarks when evaluating an institution’s performance in radiation dose reduction.”

According to the study, published in the American Journal of Roentgenology, ongoing efforts are being made to reduce radiation doses at the institutional level and these dose reductions are being reported to registries and databases allowing cross-institutional comparisons. These efforts will make important reductions in unnecessary radiation exposure during imaging procedures, Eisenberg and colleagues wrote; however, as dose reductions are pushed further, if similar dose reduction protocols are applied to all patients, those patients with the least risk for cancer, such as patients older than age 65, could be adversely effected.

To explore this further, Eisenberg and colleagues created a model to project health benefits from dose reduction protocols designed to decrease exposure from abdominopelvic CT examinations. They compared projected radiation-induced cancer risks in a hypothetical program where radiation reduction was applied equally across all CT scans with a hypothetical program where radiation dose reductions were age-dependent.

For the analysis, they drew from 20,979 CT scans performed at their institution in 2011. Of these scans, 39 percent were performed in patients aged 65 or older. The researchers found that if dose reductions had been applied across all patients, the maximum number of lethal cancers avoided was seven per 100,000 people. This number correlated to a maximum possible life expectancy gain of 0.26 days per patient. The researchers then restricted the analysis to only those patients aged 20 to 64 and found that the number of lethal cancers avoided decreased to five per 100,000 with a life expectancy gain of 0.22 days.

“However, because patients 65 years old and older contributed substantially to the institution’s average effective dose, a dose-reduction program that was restricted to patients younger than 65 years yielded a substantially higher average effective dose of 8.2 mSv, as compared with 7 mSv,” the researchers wrote.

The researchers supported their findings that 39 percent of patients were aged 65 or older by examining previously published data on the age-frequency distribution of abdominopelvic CT. Data from a national level showed that 36.2 percent of abdominopelvic CT cases were performed in patients aged older than 65.

Eisenberg and colleagues acknowledged that the development of patient-centered dose-reduction algorithms will be challenging.

“Nevertheless, patient-centered practices must become a priority within the imaging community in the coming years, and attention to basic patient characteristics that govern-radiation-induced cancer risks is essential for providing the best possible care,” they wrote.