Characterization of MOSkin detector for in vivo skin dose measurement during megavoltage radiotherapy

摘要

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 MO Skin detector , on surface for in vivo skin dosimetry. The advantages of the MO Skin 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 MO Skin 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 MO Skin detector and compared with Markus ionization chamber and GAFCHROMIC EBT2 film measurements. Dependence in the response of the MO Skin 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 MO Skin detector showed excellent reproducibility and linearity for dose range of 50 cGy to 300 cGy. The MO Skin detector showed reliable response to different SSDs, field sizes, surface, radiation incident angles, and wedges. The MO Skin detector is suitable for in vivo skin dosimetry.PACS number: 87.55.Qr