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Lens dose to standing patients treated with electrons to the hand.

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Bibliographic Details
Title: Lens dose to standing patients treated with electrons to the hand.
Authors: Van Schelt, Jonathon1 (AUTHOR) jonathon_vanschelt@rush.edu
Source: Medical Dosimetry. Winter 2021, Vol. 46 Issue 4, pe7-e10. 4p.
Subjects: Electrons, Crystal glass, Linear accelerators, Curriculum
Abstract: Patients receiving radiotherapy to the hand are sometimes treated standing, with their heads beside and potentially facing an electron applicator. This raises the possibility of consequential lens dose from scattered electrons, which this study investigates. This study measures the dose beside an applicator at a depth of 3 mm in a phantom as an estimate of lens dose for such patients. The lens dose is investigated as a function of height, distance, beam energy, applicator size, and cutout fill on a Varian Trilogy linear accelerator. The effect of the potential mitigation strategies of turning the head or shielding with lead sheets is also investigated. Measurement found that a typical hand setup may result in the lens receiving 0.15% of the treatment dose, which would deliver a cumulative dose above the demonstrated threshold dose for cataract risk for some courses. Large applicators and close facial proximity to the applicator separately enhance dose by factors of 3 and 5 respectively, raising the possibility of multiple gray to the lens for patients in unfavorable setups. Simple and effective mitigation strategies are available: Turning the patient's head to the side or placing 1–2 mm of lead on glasses reduced lens dose by a factor of 3–4, and covering the side of the applicator with 1 mm of lead or turning the head completely away effectively eliminated lens dose. The lens dose can be consequential but is readily mitigated. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Patients receiving radiotherapy to the hand are sometimes treated standing, with their heads beside and potentially facing an electron applicator. This raises the possibility of consequential lens dose from scattered electrons, which this study investigates. This study measures the dose beside an applicator at a depth of 3 mm in a phantom as an estimate of lens dose for such patients. The lens dose is investigated as a function of height, distance, beam energy, applicator size, and cutout fill on a Varian Trilogy linear accelerator. The effect of the potential mitigation strategies of turning the head or shielding with lead sheets is also investigated. Measurement found that a typical hand setup may result in the lens receiving 0.15% of the treatment dose, which would deliver a cumulative dose above the demonstrated threshold dose for cataract risk for some courses. Large applicators and close facial proximity to the applicator separately enhance dose by factors of 3 and 5 respectively, raising the possibility of multiple gray to the lens for patients in unfavorable setups. Simple and effective mitigation strategies are available: Turning the patient's head to the side or placing 1–2 mm of lead on glasses reduced lens dose by a factor of 3–4, and covering the side of the applicator with 1 mm of lead or turning the head completely away effectively eliminated lens dose. The lens dose can be consequential but is readily mitigated. [ABSTRACT FROM AUTHOR]
ISSN:09583947
DOI:10.1016/j.meddos.2021.04.005