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Dosimetry of indigenously developed <sup>177</sup>Lu patch source for surface brachytherapy-Experimental and Monte Carlo methods.

Author
Abstract
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This paper describes the evaluation of dosimetry characteristics of an in-house developed Lu skin patch source for treatment of non-melanoma skin cancer. A Lu skin patch source based on Nafion-115 membrane backbone containing 3.46 ± 0.01 mCi of activity was used. Activity measurement of the patch source was based on gamma ray spectrometry using a HPGe detector. The efficiencies of the HPGe detector were fitted using an orthogonal polynomial function. The absorbed dose rate to water at 5 μm depth in water was determined using an extrapolation chamber, EBT3 Gafchromic film and compared with Monte Carlo methods. The correction factors such as Bragg-Gray stopping power ratio of water-to-air and chamber wall material being different from water, needed to be applied on measurements for establishing the dose rate at 5 μm depth, were calculated using the Monte Carlo method. Absorbed dose rate at 5 μm depth in water (surface dose rate) measured using an extrapolation chamber and EBT3 Gafchromic film were 9.9 ± 0.7 and 8.2 ± 0.1 Gy h mCi respectively for the source activity of 3.46 ± 0.01 mCi. The surface dose rate calculated using the Monte Carlo method was 8.7 ± 0.2 Gy h mCi, which agrees reasonably well with measurement. The measured dose rate per mCi offers scope for ascertaining treatment time required to deliver the dose for propitious therapeutic outcome. Additionally, on-axis depth dose and lateral dose profiles at 5 μm and 1 mm depth in water phantom were also calculated using the Monte Carlo method.

Year of Publication
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2019
Journal
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Journal of radiological protection : official journal of the Society for Radiological Protection
Volume
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39
Issue
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1
Number of Pages
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54-70
ISSN Number
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0952-4746
URL
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https://doi.org/10.1088/1361-6498/aaeeb6
DOI
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10.1088/1361-6498/aaeeb6
Short Title
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J Radiol Prot
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