A new approach to the problems of extremity dosimetry

Extremity dosemeters are usually designed as skin dosemeters and as such should be capable of measuring dose equivalents to the radiosensitive cells of skin. Current designs of extremity dosemeter used in the NRPB extremity monitoring service employ thermoluminescent LiF as the detector in powder form contained in polyethylene sachets or finger stalls. These designs are too thick (30 mg.cm-2) for the measurement of skin dose. However, Vinten Instruments have developed a new extremity dosemeter with an effective thickness of approximately 12 mg.cm-2 capable of making adequate measurements of beta rays with energy spectra with maximum energies above 0.2 MeV and mean energies greater than 0.06 MeV. Its dosimetric performance has been assessed at NRPB and found to be very satisfactory and trials have been carried out successfully with eleven customers over a six month period. As a result a decision has been taken to introduce the dosemeter into service towards the end of 1985. (author)