Radiation Exposure from the Patient Perspective: An Argument for the Inclusion of Dose History

Patients in diagnostic imaging departments often ask about the risk of injury from x radiation. They are referred to wall posters or consent forms that declare (rightly) that the risk of harm from the proposed exam is very small and is far outweighed by the benefit. If a comparative risk value is provided, most likely it is based on a single exposure and derived from population estimates of cancer incidence and mortality. But is that information the most relevant for the patient? In a recent position statement, the AAPM recommends that only current exam risk should be considered, and that risk is independent of previous exams. We argue that if an exam carries risk of a negative event, the likelihood that a negative event occurred over all events increases with the number of exams. This cumulative risk, though still very small, must be a relevant consideration for health management.