The design and preliminary test results of a semiconductor silicon dosimeter are presented in this article. Use of this dosimeter is foreseen for real-time skin dose control in interventional radiology. The strong energy dependence of this kind of radiation detector is well overcome by filtering the silicon diode. Here, the optimal filter features have been calculated by numerical Monte Carlo simulations. A prototype has been built and tested in a radiological facility. The first experimental results show a good match between the filtered semiconductor diode response and an ionization chamber response, within 2% fluctuation in a 2.2 to 4.1 mm Al half-value layer (HVL) energy range. Moreover, the semiconductor sensor response is linear from 0.02 Gy/min to at least 6.5 Gy/min, covering the whole dose rate range found in interventional radiology. The results show that a semiconductor dosimeter could be used to monitor skin dose during the majority of procedures using x-rays below 150 keV. The use of this device may assist in avoiding radiation-induced skin injuries and lower radiation levels during interventional procedures.

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Cadmium telluride, a semiconductor compound with high Z is presently used at room temperature as a gamma ray detector. We have used this material to detect thermal neutrons by making use of the very high cross section of 113Cd to absorb thermal neutrons and emit gamma rays. Two CdTe detectors were exposed to a known thermal neutron beam at the CRN reactor, in order to analyse the performance of this device and a Monte Carlo code was developed to determine the expected response spectrum. For the two devices considered here under a series of experimental conditions, satisfactory agreement was observed between calculations and experimental data. Some of the 113Cd(n,?) radiative capture lines were identified by calibrating the detector with 57Co source. Since the atomic density of CdTe is much higher than in gas detectors, the efficiency under a small volume is very high, even if the total volume is presently limited to 10 x 10 x 2 mm3. In using CdTe as a thermal neutron dosemeter, it is best to use for calibration the line at 560 keV emitted and detected in the same device.

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