A method for a real time estimation of entrance skin dose distribution in interventional neuroradiology

Interventional neuroradiology can involve very high entrance skin doses to patients and has the potential to induce deterministic radiation effects to the skin. A monitoring system indicating the maximum entrance skin dose during procedures could be useful to avoid skin injuries and to optimize technical parameters. Such evaluation is difficult, because exposure conditions change many times during each procedure. A data acquisition system for real time estimation of patient dose was developed, using a transmission ionization chamber connected to a personal computer, simultaneously measuring air kerma and dose area product. Input data were processed by a software that provided a map of entrance skin dose and stored all the information in a database. The method was first applied during 16 interventional procedures and was found to be suitable to this application thanks to the short time necessary for dose measurements, simplicity of use and absence of interference with the procedure execution. The uncertainty of estimation of maximum entrance skin dose was evaluated to be about 20% at the 1 sigma level.