A new microcontroller-based RADFET dosimeter reader

A new reader for radiation dose measurements using RADFET (pMOSFET) dosemeters has been developed. The threshold voltage (VT) of the pMOSFETs is measured using a “one-point” method that determines VT as the gate voltage for a given drain current. Using VT, the absorbed dose, which is directly proportional to the threshold voltage shift, is calculated. The reader is based on a low cost 8-bit PIC 18F4520 microcontroller (MCU), and works independently of a personal computer, uses a touch screen and stores the data in microcontroller memory. Good agreement in threshold voltage values, obtained using a high-quality source-measure unit and the reader, was obtained. In addition, the reader can be used for threshold voltage measurement with other types of MOSFETs, especially in long duration experiments, as well as for the real-time measurements in radiotherapy, either as an autonomous system or integrated in a larger monitoring configuration.

► The paper describes a reader for radiation dose measurements.
► The reader is based on a low cost commercially available microcontroller.
► It works independently of a PC, using a touch panel display for control.
► The good agreement in threshold voltage values was obtained when tested.