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Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine

AIM: The objective of this study was to evaluate skin dose based on retrofit prototype multileaf collimators (MLCs), designed for cobalt-60 teletherapy machine. Since patient's skin is sensitive to radiation, evaluation of skin dose is of utmost importance for investigating the risk of late eff...

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Autores principales: Rani, Akula Roopa, Ayyangar, Komanduri, Reddy, A. R., Kumar, Ayyalasomayajula Anil, Reddy, Pal Reddy Yadagiri
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Wolters Kluwer - Medknow 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8074722/
https://www.ncbi.nlm.nih.gov/pubmed/33953496
http://dx.doi.org/10.4103/jmp.JMP_25_20
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author Rani, Akula Roopa
Ayyangar, Komanduri
Reddy, A. R.
Kumar, Ayyalasomayajula Anil
Reddy, Pal Reddy Yadagiri
author_facet Rani, Akula Roopa
Ayyangar, Komanduri
Reddy, A. R.
Kumar, Ayyalasomayajula Anil
Reddy, Pal Reddy Yadagiri
author_sort Rani, Akula Roopa
collection PubMed
description AIM: The objective of this study was to evaluate skin dose based on retrofit prototype multileaf collimators (MLCs), designed for cobalt-60 teletherapy machine. Since patient's skin is sensitive to radiation, evaluation of skin dose is of utmost importance for investigating the risk of late effects. MATERIALS AND METHODS: Measurements were performed with a Phoenix cobalt-60 teletherapy machine and the detector used was EBT3 radiochromic film. The experiments were performed in a solid water phantom with two prototype MLCs mounted to the machine. Dose readings were taken by placing the films at source-to-surface distance (SSD) of 60 cm, 65 cm, 70 cm, 75 cm, 80 cm, 85 cm, and 90 cm for various MLC-generated field sizes starting from 2 cm × 2 cm to 14 cm × 14 cm. The films were analyzed using custom made programs. The measured doses were normalized to the dose at dmax for that particular measurement of SSD. RESULTS: The skin dose is expressed as a percentage of dose at dose maximum. In general, the skin dose increases with field size and decreases with SSD. The measurements indicate surface doses within 20%–60% for the investigated SSD range. Furthermore, there is no significant difference between the surface doses of two prototype MLCs studied. CONCLUSIONS: From the measurements, it can be concluded that there is good skin sparing even at close distance to the MLCs. The skin dose is <50% for SSDs >65 cm. A minimum gap of 5 cm is required to produce acceptable skin dose.
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spelling pubmed-80747222021-05-04 Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine Rani, Akula Roopa Ayyangar, Komanduri Reddy, A. R. Kumar, Ayyalasomayajula Anil Reddy, Pal Reddy Yadagiri J Med Phys Original Article AIM: The objective of this study was to evaluate skin dose based on retrofit prototype multileaf collimators (MLCs), designed for cobalt-60 teletherapy machine. Since patient's skin is sensitive to radiation, evaluation of skin dose is of utmost importance for investigating the risk of late effects. MATERIALS AND METHODS: Measurements were performed with a Phoenix cobalt-60 teletherapy machine and the detector used was EBT3 radiochromic film. The experiments were performed in a solid water phantom with two prototype MLCs mounted to the machine. Dose readings were taken by placing the films at source-to-surface distance (SSD) of 60 cm, 65 cm, 70 cm, 75 cm, 80 cm, 85 cm, and 90 cm for various MLC-generated field sizes starting from 2 cm × 2 cm to 14 cm × 14 cm. The films were analyzed using custom made programs. The measured doses were normalized to the dose at dmax for that particular measurement of SSD. RESULTS: The skin dose is expressed as a percentage of dose at dose maximum. In general, the skin dose increases with field size and decreases with SSD. The measurements indicate surface doses within 20%–60% for the investigated SSD range. Furthermore, there is no significant difference between the surface doses of two prototype MLCs studied. CONCLUSIONS: From the measurements, it can be concluded that there is good skin sparing even at close distance to the MLCs. The skin dose is <50% for SSDs >65 cm. A minimum gap of 5 cm is required to produce acceptable skin dose. Wolters Kluwer - Medknow 2020 2021-02-02 /pmc/articles/PMC8074722/ /pubmed/33953496 http://dx.doi.org/10.4103/jmp.JMP_25_20 Text en Copyright: © 2021 Journal of Medical Physics https://creativecommons.org/licenses/by-nc-sa/4.0/This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
spellingShingle Original Article
Rani, Akula Roopa
Ayyangar, Komanduri
Reddy, A. R.
Kumar, Ayyalasomayajula Anil
Reddy, Pal Reddy Yadagiri
Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine
title Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine
title_full Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine
title_fullStr Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine
title_full_unstemmed Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine
title_short Estimation of Skin doses for Retrofit Prototype Multileaf Collimators Designed for Telecobalt Therapy Machine
title_sort estimation of skin doses for retrofit prototype multileaf collimators designed for telecobalt therapy machine
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8074722/
https://www.ncbi.nlm.nih.gov/pubmed/33953496
http://dx.doi.org/10.4103/jmp.JMP_25_20
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