Medical radiation sources are used deliberately in the healthcare of patients and are designed for use in a controlled manner. There obviously are some adverse health risks associated with the use of radiation in medicine (ICRP Publication 105 Radiological Protection in Medicine), with higher amounts of radiation being associated with higher risks. The undisputed health benefits of diagnostic radiology (ICRP Publication 121 Radiological Protection in Paediatric Diagnostic and Interventional Radiology, ICRP Publication 102 Managing Patient Dose in Multi-Detector Computed Tomography (MDCT), ICRP Publication 87 Managing Patient Dose in Computed Tomography) using x-ray or nuclear medicine (Publication 128) may be accompanied by a generally very small risk (probability) of deleterious effects, while in radiation therapy (ICRP Publication 127 Radiological Protection in Ion Beam Radiotherapy, ICRP Publication 98 Radiation Safety Aspects of Brachytherapy for Prostate Cancer using Permanently Implanted Sources, ICRP Publication 97: Prevention of High-dose-rate Brachytherapy Accidents, ICRP Publication 86 Prevention of Accidents to Patients Undergoing Radiation Therapy), such risk can be much higher as large amounts of radiation are required.
In medicine, the aim of managing radiation exposure is to minimise the presumed low risk without sacrificing, or unduly limiting, the obvious benefits in the prevention, diagnosis, and effective cure of diseases. Using a larger amount of radiation cannot be justified if a smaller amount can deliver the expected benefits, but too low an amount of radiation in diagnostic radiology will result in an image that does not have enough information to make a diagnosis, and in radiation therapy, not delivering enough radiation will result in increased mortality because the cancer being treated will not be cured.
Experience has provided ample evidence that reasonable selection of the conditions under which ionising radiation is being used in medicine can lead to health benefits substantially outweighing the estimated possible deleterious effects.
Medical exposures during pregnancy require specific consideration due to the radiation sensitivity of the developing embryo/fetus. Before any exposure using ionising radiation, it is important to determine whether a female patient is, or could be, pregnant. Prenatal doses from most correctly performed diagnostic procedures present no measurably increased risk of prenatal death, developmental damage including malformation, or impairment of mental development over the background incidence of these entities. The benefits to the mother of obtaining important diagnostic information for her treatment is very likely to outweigh this risk. However, higher doses, such as those involved in therapeutic procedures, have the potential to result in developmental harm or cancer induction in unborn babies. The pregnant patient has a right to know the magnitude and type of potential radiation effects that may result from in-utero exposure. Detailed discussions with her physician are highly encouraged. Pregnant patients should note that the incidences of fetal anomalies, with or without routine medical imaging, are similar to baseline background event rates. These include a 15% rate of spontaneous abortion, a 4–10% incidence of genetic abnormalities, a 4% risk of intrauterine growth retardation, and a 2–4% incidence of major malformation ( ; ICRP Publication 84).
Children are considered, in general, more sensitive to radiation exposure than adults in view of growing tissues and longer life expectancy. Some tissues in children are more sensitive to radiation than those in Adults. For this reason, further caution should be exercised when ionising radiation is used to image children.