JACR: Repeated imaging raises cancer risk for patients with chronic conditions

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Patients with chronic and recurrent conditions receive radiation exposures that may put them at increased risk for cancer via medical imaging, according to a study published in the May edition of the Journal of the American College of Radiology, which found that the proportion of these patients who received estimated total effective doses of greater than 50 mSv within three years was significantly higher for those diagnosed most recently.

According to Evan G. Stein, MD, PhD, and colleagues from the department of radiology at Albert Einstein College of Medicine, Montefiore Medical Center in the Bronx, N.Y., “Advances in medical imaging have been associated with increased utilization and increased radiation exposure,” especially for patients with chronic and recurrent conditions including hydrocephalus, pulmonary thromboembolic disease, renal colic and cardiac disease.

In this study, the researchers estimated the cumulative radiation doses from medical imaging for specific cohorts of these patients.

From Jan. 1, 2000, to Dec. 31, 2005, the investigators retrospectively identified all patients diagnosed with hydrocephalus (1,711), pulmonary thromboembolic disease (3,220), renal colic (5,855) and cardiac disease (11,072) by way of Clinical Looking Glass, a software application developed at the medical center, which enabled Stein and colleagues to acquire index encounters of the four cohorts from the emergency department, inpatient and outpatient services during the study period.

The authors said that each imaging examination that used ionizing radiation from 2000 to 2008 was incorporated into an estimate of total effective dose and organ-specific doses. The patients with high levels of radiation exposure after three years (total effective dose greater than 50 mSv; and dose to the ocular lens greater than 150 mSv) were identified.

For the surviving cohorts after three years, the average estimated effective doses were found to be 12.3 mSv for patients with hydrocephalus, 21.7 mSv for those with pulmonary thromboembolic disease, 18.7 mSv for those with renal colic and 14 mSv for patients with cardiac disease. The authors also found that within hydrocephalus cohort, 26.3 percent (339 of 1,291) had radiation doses greater than 150 mSv to the ocular lens within three years. In addition, the proportion of patients with total effective doses  greater than 50 mSv within three years was determined to be “significantly higher” for those diagnosed in 2004 and 2005 compared to those diagnosed in 2000 and 2001.

Stein and colleagues said that their study demonstrates that within three years, surviving patients with hydrocephalus, pulmonary thromboembolic disease, renal colic or cardiac disease received estimated radiation doses that may put them at increased risk for cancer.

“A variety of strategies are necessary to reduce the rapid rise in imaging with ionizing radiation,” said the authors, noting that educating clinicians, radiologists and technologists will play a critical role in radiation reduction. “It is the responsibility of institutions and physicians to critically evaluate their infrastructures, diagnostic strategies and imaging techniques for each individual patient, with an eye toward minimizing cumulative medical radiation exposure,” they concluded.