Evaluating the Performance of a Direct Ion Storage Dosimeter at Diagnostic X-ray Energies

Radiation protection for the physician is very important in interventional radiology (IVR), as some have been injured performing IVR. The radiation dose to the physician should be monitored in real-time, but unfortunately this is not possible with most radiation monitors. The Direct Ion Storage (DIS) dosimeter, a structure that combines a microminiature ionization chamber with a field effect transistor (FET), is a small dosimeter that is based on a new principle. A DIS dosimeter enables real-time measurements. We carried out a fundamental evaluation of whether a DIS dosimeter is suitable as a personal dosimeter in IVR using diagnostic X-ray apparatus. In this study, DIS measurements of 1-cm and 70-μm dose equivalents were evaluated. We investigated the performance (angle dependence, linearity, reproducibility, and stability) of the DIS. The sensitivity of the angle dependence of the DIS exceeded 80% over a range of ±60°. The DIS had good reproducibility and stability. Furthermore, it had good linearity, and was able to make measurements at a high dose rate. Therefore, the DIS dosimeter performs sufficiently well at diagnostic X-ray energies to use for monitoring radiation exposure in real time during IVR