Radiation exposure from X-ray examinations today is minimal. Contemporary X-ray systems deliver a very brief and narrow beam of radiation. Exposure is reduced by limiting beam size and exposure with lead shielding devices when appropriate and by limiting the duration of the exposure.
Though pregnant patients or pregnant personnel are of concern with respect to radiation exposure, the American College of Radiology states that there is no single X-ray procedure that results in radiation exposure intense enough to threaten the wellbeing of an embryo or fetus. The American College of Obstetricians and Gynecologists have taken a similar position. An embryo or fetus can be exposed to a cumulative dose of 5 rads of radiation with no ill effects. A chest X-ray delivers 0.00007 rads, a negligible amount.
When examination can’t be postponed until after delivery, the fetus can be protected by the use of lead shielding and coning techniques. Patients should inform the technologist if there is a possibility of pregnancy before the examination.
Nuclear medicine or PET examinations involve the use of trace quantities injected radiopharmaceuticals. These substances deliver small radiation exposures, which are generally equivalent to exposure from x-ray or CT exams. Nuclear medicine examination is usually not recommended during pregnancy.
In general, physicians refer for such examination when the benefit of examination outweighs any risk.