Real-time quantification and display of skin radiation during coronary angiography and intervention

Background - Radiographically guided investigations may be associated with excessive radiation exposure, which may cause skin injuries. The purpose of this study was to develop and test a system that measures in real time the dose applied to each 1-cm² area of skin, taking into account the movement of the x-ray source and changes in the beam characteristics. The goal of such a system is to help prevent high doses that might cause skin injury. Methods and Results - The entrance point, beam size, and dose at the skin of the patient were calculated by use of the geometrical settings of gantry, investigation table, and x-ray beam and an ionization chamber. The data are displayed graphically. Three hundred twenty-two sequential cardiac investigations in adult patients were analyzed. The mean peak entrance dose per investigation was 0.475 Gy to a mean skin area of 8.2 cm². The cumulative KERMA-area product per investigation was 52.2 Gy/cm² (25.4 to 99.2 Gy/cm²), and the mean entrance beam size at the skin was 49.2 cm². Twenty-eight percent of the patients (90/322) received a maximum dose of <1 Gy to a small skin area (≈6 cm²), and 13.5% of the patients (42/322) received a maximum dose of >2 Gy. Conclusions - Monitoring of the dose distribution at the skin will alert the operator to the development of high-dose areas; by use of other gantry settings with nonoverlapping entrance fields, different generator settings, and extra collimation, skin lesion can be avoided.