Purpose: To simulate dose to the skin of a large patient for various operational fluoroscopic conditions and to delineate how to adjust operational conditions to maintain skin dose at acceptable levels.
Materials and methods: Patient entrance skin dose was estimated from measurement of entrance air kerma (dose to air) to a 280-mm water phantom for two angiographic fluoroscopes. Effects on dose for changes in machine floor kVp, source-to-skin distance, air gap, electronic magnification, fluoroscopic dose rate control settings, and fluorographic dose control settings were examined.
Results: Incremental changes in operational parameters are multiplicative and markedly affect total dose delivered to a patient's skin. For long procedures, differences in doses of 8 Gy or more are possible for some combinations of operational techniques.
Conclusions: Effects on skin dose from changes in operational parameters are multiplicative, not additive. Doses in excess of known thresholds for injury can be exceeded under some operating conditions. Adjusting operational parameters appropriately will markedly reduce dose to a patient's skin. Above all other operational factors, variable pulsed fluoroscopy has the greatest potential for maintaining radiation exposure at low levels.