Radiation exposure in nuclear medicine differs from external beam imaging because the radioactive source is inside the patient. This means that exposure control must address both patient dose and occupational exposure.

For patients, minimisation begins with justification ensuring that the study is clinically necessary. Optimisation then involves selecting the appropriate tracer and administered activity to produce adequate image quality without unnecessary dose.

Because radiation dose depends on cumulated activity, encouraging rapid biological clearance reduces dose. Hydration and frequent voiding can significantly reduce bladder wall dose after many radiopharmaceuticals.

For staff, exposure reduction relies on basic radiation protection principles.

Reducing time near radioactive sources decreases cumulative exposure because dose is proportional to exposure duration.

Increasing distance reduces exposure according to the inverse square law. Even small increases in distance can significantly reduce dose.

Using appropriate shielding attenuates emitted photons. In nuclear medicine, shielding must match photon energy. For example, higher-energy 511 keV photons from PET require denser or thicker shielding than lower-energy gamma emissions.

Handling techniques, automated dispensing systems, syringe shields, and remote injection devices further reduce occupational exposure.

Importantly, most diagnostic nuclear medicine exposures are well below regulatory dose limits, but adherence to ALARA remains essential.