Polycrystalline diamond detectors compared with silicon X-ray dosimeters for clinical use

Physical and metering characteristics of three room temperature X-ray dosimeters used in clinical applications, PTW diamond, Thompson MOSFET and Scanditronix silicon diode are compared with polycrystalline diamond X-ray detectors. Development of dosimeters based on natural diamond carried out by PTW have provided superior characteristics with respect to other solid state silicon devices such diodes or MOSFETs. Radiation hardness, soft tissue equivalence, lack of toxicity, negligible energy dependence and optimal sensitivity and reproducibility, have made PTW the ideal metering device for clinical dosimetry. However general use of natural dosimeters have been hindered by their rarity, very high cost and unpredictable electronic behavior due to lack of control on impurity content and crystal defects. Therefore, there have been a growing use of silicon dosimeters especially for on line configuration and in vivo dosimetry. However, both MOSFET and silicon diode do not appear to be ideal for such application for their short lifetime. Detectors based on polycrystalline diamonds seem to be the best candidate for future dosimetry since they have most of the characteristics of natural diamonds at potentially much lower cost. In this context, the performances of a laboratory made polycrystalline diamond device are compared to those of the three, PTW, Scanditronix and Thomson commercial dosimeters.