April 1, 2009 – The April 2009 issue of the Harvard Heart Letter explores the delicate balance between benefit and risk and demands the judicious use of radiation for diagnosing and treating disease.
The amount of radiation delivered by medical tests or procedures varies widely. While a chest X-ray delivers a tiny fraction of the amount of natural background radiation we receive each year, CT scans and some nuclear stress tests deliver up to 10 times the annual background dose.
Although the cancer risk from a single medical test or procedure is low, it is estimated that radiation from CT scans now accounts for 1.5 percent of all cancers in the U.S.
The Harvard Heart Letter notes that patients shouldn’t agree to or ask for medical testing that involves radiation unless it will give important information about a patient’s health. And even then, patients should ask for the lowest radiation dose possible.
For more information: www.health.harvard.edu/heart
June 25, 2025 
