Protocols developed for high-energy dosimetry IAEA (Technical Reports Series No. 277, 1997), AAPM (Med. Phys. 10 (1983) 741: Med. Phys. 18 (1991) 73: Med. Phys. 21 (1994) 1251), IPEMB (Phys. Med. Biol. 41 (1996) 2557), and HPA (Phys. Med. Biol. 28 (1983) 1097) have continued to enhance precision in dose measurements and the optimization of radiotherapy procedures. While recent dosimetry protocols, including those due to the IAEA and IPEMB, have made a number of improvements compared with previous protocols, it is further desirable to develop absolute dosimetry methods of dose measurements. Measurements based on careful implementation of procedures contained within the various protocols have been carried out in an effort to determine the extent to which discrepancies exist among the protocols. Dose in water at dmax was measured using cylindrical and parallel-plate ionization chambers for 6 MV photon beams and 5 and 12 MeV electron beams. Results obtained from the use of the AAPM and HPA protocols for 6 MV photon beams were found to be 0.9% larger and 0.1% smaller, respectively, than those measured following the IAEA protocol. Calibration dose measurements for 5 and 12 MeV electron beams in water phantoms were found to agree to within 1%, this being well within recommendations from the ICRU and other sources regarding the accuracy of dose delivery.
In vivo dosimetry is important during radiotherapy to ensure the accuracy of the dose delivered to the treatment volume. A dosimeter should be characterized based on its application before it is used for in vivo dosimetry. In this study, we characterize a new MOSFET-based detector, the MOSkin detector, on surface for in vivo skin dosimetry. The advantages of the MOSkin detector are its water equivalent depth of measurement of 0.07 mm, small physical size with submicron dosimetric volume, and the ability to provide real-time readout. A MOSkin detector was calibrated and the reproducibility, linearity, and response over a large dose range to different threshold voltages were determined. Surface dose on solid water phantom was measured using MOSkin detector and compared with Markus ionization chamber and GAFCHROMIC EBT2 film measurements. Dependence in the response of the MOSkin detector on the surface of solid water phantom was also tested for different (i) source to surface distances (SSDs); (ii) field sizes; (iii) surface dose; (iv) radiation incident angles; and (v) wedges. The MOSkin detector showed excellent reproducibility and linearity for dose range of 50 cGy to 300 cGy. The MOSkin detector showed reliable response to different SSDs, field sizes, surface, radiation incident angles, and wedges. The MOSkin detector is suitable for in vivo skin dosimetry.