Dosimetric Comparison of Superficial X-Rays and a Custom HDR Surface Applicator for the Treatment of Superficial Cancers
The purpose of this study was to design and characterize a custom HDR applicator for the treatment of cancers in the region 0-5 mm, comparing it to the dosimetric properties of the MaximaR-100 superficial x-ray unit. The superficial machine was characterized in terms of percent depth dose, beam profiles, and dose rate and similar measurements were taken for the copper HDR applicator. The applicator alone had an unacceptably large dose inhomogeneity across the beam so a primary filter, modified filter, and secondary lead collimator were designed and manufactured to help shape the dose into a profile similar to the superficial applicator. Beam flatness and width were nearly replicated but beam divergence was more pronounced for the HDR applicators. Percent depth dose measurements for the HDR applicator showed a dose fall-off nearly identical to superficial x-rays rather than the assumed inverse square dose fall-off.
School:University of Toledo Health Science Campus
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:hdr orthovoltage custom applicator filter superficial flattening
Date of Publication:01/01/2008