X-ray dose to the skin in patients undergoing percutaneous transluminal coronary angioplasty

Dose measurements were performed with an ionization chamber placed on the surface of a polystyrene phantom to estimate the radiation dose to the skin from fluoroscopy in patients undergoing PTCA and to define parameters predicting for high-risk irradiation conditions. Dose rate changes were analyzed as a function of phantom thickness, X-ray source-to-phantom distance, image intensifier-to-phantom distance, and field size. Skin dose calculations were made in 38 PTCA patients to validate the model. Thickness was the most important factor determining dose rate changes in the phantom's surface. Dose rate increased by a factor of almost 4 with each 10-cm increment in thickness, doubled upon decreasing the field diameter from 17 cm to 14 cm, and increased by a factor of 1.2 to 1.8 upon decreasing the source-to-phantom distance or by increasing the image intensifier-to-patient distance. All these parameters may significantly increase the dose to the skin and augment the risk for skin injuries post-PTCA.