Is the MOSFET Dosimeter Feasible at Diagnostic X-Ray Energies for Interventional Radiology?

Abstract

To reduce the risk of skin injury during interventional radiology (IVR) procedures, it has been suggested that physicians track patients’ dose. However, the patient’s skin dose is very rarely monitored because of the lack of a feasible method for use in IVR. The metal oxide semiconductor field effect transistor (MOSFET) dosimeter is designed to measure patient exposure dose during radiotherapy applications at megavoltage photon energies. Our purpose in this preliminary study was to evaluate the feasibility of using a MOSFET dosimeter to measure patients’ skin dose during exposure to diagnostic X-ray energies used in IVR.

Dose measurements were performed using the OneDose^TM dosimetry system (OneDose). This small system uses a dosimeter based on MOSFET technology. OneDose measurements were compared with measurements obtained using a calibrated thimble-type 6-mL ion chamber. The energy dependence of the OneDose system was measured at 60-120 kV (tube voltage) on diagnostic X-ray equipment. The dependence of the OneDose sensor on the X-ray beam angle in air was measured. Variation in the sensitivity of the OneDose sensor was evaluated.

The OneDose dosimetry system showed high sensitivity, and the responses were roughly uniform from 60 to 120kV, and its response was nearly angle-independent. There was little variation in the sensitivity of multiple OneDose sensors. The One- Dose is almost invisible on X-ray images at diagnostic energies.

Although the OneDose system does not provide real-time dose monitoring, it will be feasible for use at diagnostic X-ray energies for measuring patients’ exposure dose during IVR.