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

Background-Radiographically guided investigations may be associated with ex cessive radiation exposure, which may cause skin injuries. The purpose of t his study was to develop and test a system that measures in real time the d ose applied to cacti 1-cm(2) area of skin, taking into account the movement of the x-ray source and changes in the beam characteristics. The goal of s uch a system is to help prevent high doses that might cause skin injury. Methods and Results-The entrance point, beani 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 investi gations in adult patients were analyzed. The mean peak entrance dose per in vestigation was 0.475 Gy to a mean skin area of 8.2 cm(2). The cumulative K ERMA-area product per investigation was 52.2 Gy/cm(2) (25.4 to 99.2 Gy/cm(2 )), and the mean entrance beam size at the skin was 49.2 cm(2). Twenty-eigh t percent of the patients (90/322) received a maximum dose of <1 Gy to a sm all skin area (approximate to6 cm(2)), and 13.5% of the patients (42/322) r eceived 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 sett ings with nonoverlapping entrance fields, different generator settings, and extra collimation, skin lesion can be avoided.