Year

2017

Degree Name

Master of Philosophy

Department

School of Physics

Abstract

Currently, TLDs and Gafchromic EBT3 film are commonly used for skin dose measurement during Total Skin Electron Therapy (TSET). However, measurements using these dosimeters is very time consuming due to post-irradiation processing requirements. Also, accurate skin dose measurements are challenging with these dosimeters since the radiosensitive layer of the skin sits at an approximate depth of 0.07mm. The MOSkin detector has advantages of being of a small physical size and submicron dosimetric volume and a water equivalent depth of 0.07mm while providing real-time dosimetry.

Measurements of the MOSkin’s dosimetric characteristics were performed using a 6 MeV electron beam with an Elekta Infinity linear accelerator at the Prince of Wales Hospital. For the TSET measurements, doses measured with the MOSkin detector were directly compared to TLDs and Gafchromic EBT3 film using a 6 MeV high dose rate electron (HDRE) beam. A 6 mm Perspex spoiler was placed and aligned perpendicularly to the beam in order to lower the effective beam energy and improve dose homogeneity.

MOSkin dose response was observed to be effectively linear over 3 Gy of the total dose. The response of the MOSkin showed the expected increase in surface dose with incident beam angle. For dose rate response, the effect on the MOSkin’s measurements was not significant. For the TSET measurements, all three detector types showed a very similar trend of dose readings over every measurement points.

The MOSkin is an effective skin dosimeter for TSET dosimetry as it provides stable skin dose readings that compared acceptably with the TLD and EBT3 film results. It also showed good dose linearity and dose rate independence for 6 MeV electron beam and behaved very similarly to the other types of dosimeters that are commonly used for TSET in vivo dosimetry.

This thesis is unavailable until Wednesday, May 01, 2019

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