The AAPM/RSNA physics tutorial for residents - Internal radiation dosimetry: Principles and applications

Internal dose calculations in nuclear medicine normally use the techniques, equations, and resources provided by the Medical Internal Radiation Dose ( MIRD) Committee of the Society of Nuclear Medicine. The MIRD schema uses a unique set of symbols and quantities to calculate the absorbed dose of radi ation in any target organ per radioactive decay in any source organ. The ca lculations involve the energy emitted per radioactive decay, the fraction o f the emitted energy that is absorbed in various target organs, the masses of these organs, and both the physical decay and biologic clearance of the injected radioactive material. Standardized mathematical models (phantoms) of the human body and standardized biokinetic models are also used. A compu ter program, MIRDose, calculates dose tables per unit administered activity of various radiopharmaceuticals. Special care must be taken when nuclear m edicine procedures involve pregnant or lactating patients. New methodologie s are becoming available to calculate doses to individual patients.