Management of patient skin dose in fluoroscopically guided interventional procedures

PURPOSE: To simulate dose to the skin of a large patient for various operat ional fluoroscopic conditions and to delineate how to adjust operational co nditions to maintain skin dose at acceptable levels. MATERIALS AND METHODS: Patient entrance skin dose was estimated from measur ement 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 kV p, source-to-skin distance, air gap, electronic magnification, fluoroscopic dose rate control settings, and fluorographic dose control settings were e xamined. RESULTS: Incremental changes in operational parameters are multiplicative a nd markedly affect total dose delivered to a patient's skin. For long proce dures, differences in doses of 8 Gy or more are possible for some combinati ons of operational techniques. CONCLUSIONS: Effects on skin dose from changes in operational parameters ar e multiplicative, not additive. Doses in excess of known thresholds for inj ury can be exceeded under some operating conditions. Adjusting operational parameters appropriately will markedly reduce dose to a patient's skin. Abo ve all other operational factors, variable pulsed fluoroscopy has the great est potential for maintaining radiation exposure at low levels.