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Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures
A revised translating bed total body irradiation (TBI) technique is developed for shielding organs at risk (lungs) to tolerance dose limits, and optimizing dose distribution in three dimensions (3D) using an asymmetrically‐adjusted, dynamic multileaf collimator. We present a dosimetric comparison of...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2016
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5875554/ https://www.ncbi.nlm.nih.gov/pubmed/27074477 http://dx.doi.org/10.1120/jacmp.v17i2.5951 |
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author | Ahmed, Shahbaz Brown, Derek Ahmed, Saad B. S. Kakakhel, Muhammad B. Muhammad, Wazir Hussain, Amjad |
author_facet | Ahmed, Shahbaz Brown, Derek Ahmed, Saad B. S. Kakakhel, Muhammad B. Muhammad, Wazir Hussain, Amjad |
author_sort | Ahmed, Shahbaz |
collection | PubMed |
description | A revised translating bed total body irradiation (TBI) technique is developed for shielding organs at risk (lungs) to tolerance dose limits, and optimizing dose distribution in three dimensions (3D) using an asymmetrically‐adjusted, dynamic multileaf collimator. We present a dosimetric comparison of this technique with a previously developed symmetric MLC‐based TBI technique. An anthropomorphic RANDO phantom is CT scanned with 3 mm slice thickness. Radiological depths (RD) are calculated on individual CT slices along the divergent ray lines. Asymmetric MLC apertures are defined every 9 mm over the phantom length in the craniocaudal direction. Individual asymmetric MLC leaf positions are optimized based on RD values of all slices for uniform dose distributions. Dose calculations are performed in the Eclipse treatment planning system over these optimized MLC apertures. Dose uniformity along midline of the RANDO phantom is within the confidence limit (CL) of 2.1% (with a confidence probability [Formula: see text]). The issue of over‐ and underdose at the interfaces that is observed when symmetric MLC apertures are used is reduced from more than [Formula: see text] to less than [Formula: see text] with asymmetric MLC apertures. Lungs are shielded by 20%, 30%, and 40% of the prescribed dose by adjusting the MLC apertures. Dose‐volume histogram analysis confirms that the revised technique provides effective lung shielding, as well as a homogeneous dose coverage to the whole body. The asymmetric technique also reduces hot and cold spots at lung‐tissue interfaces compared to previous symmetric MLC‐based TBI technique. MLC‐based shielding of OARs eliminates the need to fabricate and setup cumbersome patient‐specific physical blocks. PACS number(s): 87.55.‐x, 87.55.de, 87.55.D‐ |
format | Online Article Text |
id | pubmed-5875554 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-58755542018-04-02 Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures Ahmed, Shahbaz Brown, Derek Ahmed, Saad B. S. Kakakhel, Muhammad B. Muhammad, Wazir Hussain, Amjad J Appl Clin Med Phys Radiation Oncology Physics A revised translating bed total body irradiation (TBI) technique is developed for shielding organs at risk (lungs) to tolerance dose limits, and optimizing dose distribution in three dimensions (3D) using an asymmetrically‐adjusted, dynamic multileaf collimator. We present a dosimetric comparison of this technique with a previously developed symmetric MLC‐based TBI technique. An anthropomorphic RANDO phantom is CT scanned with 3 mm slice thickness. Radiological depths (RD) are calculated on individual CT slices along the divergent ray lines. Asymmetric MLC apertures are defined every 9 mm over the phantom length in the craniocaudal direction. Individual asymmetric MLC leaf positions are optimized based on RD values of all slices for uniform dose distributions. Dose calculations are performed in the Eclipse treatment planning system over these optimized MLC apertures. Dose uniformity along midline of the RANDO phantom is within the confidence limit (CL) of 2.1% (with a confidence probability [Formula: see text]). The issue of over‐ and underdose at the interfaces that is observed when symmetric MLC apertures are used is reduced from more than [Formula: see text] to less than [Formula: see text] with asymmetric MLC apertures. Lungs are shielded by 20%, 30%, and 40% of the prescribed dose by adjusting the MLC apertures. Dose‐volume histogram analysis confirms that the revised technique provides effective lung shielding, as well as a homogeneous dose coverage to the whole body. The asymmetric technique also reduces hot and cold spots at lung‐tissue interfaces compared to previous symmetric MLC‐based TBI technique. MLC‐based shielding of OARs eliminates the need to fabricate and setup cumbersome patient‐specific physical blocks. PACS number(s): 87.55.‐x, 87.55.de, 87.55.D‐ John Wiley and Sons Inc. 2016-03-08 /pmc/articles/PMC5875554/ /pubmed/27074477 http://dx.doi.org/10.1120/jacmp.v17i2.5951 Text en © 2016 The Authors. This is an open access article under the terms of the http://creativecommons.org/licenses/by/3.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Radiation Oncology Physics Ahmed, Shahbaz Brown, Derek Ahmed, Saad B. S. Kakakhel, Muhammad B. Muhammad, Wazir Hussain, Amjad Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures |
title | Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures |
title_full | Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures |
title_fullStr | Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures |
title_full_unstemmed | Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures |
title_short | Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures |
title_sort | translating bed total body irradiation lung shielding and dose optimization using asymmetric mlc apertures |
topic | Radiation Oncology Physics |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5875554/ https://www.ncbi.nlm.nih.gov/pubmed/27074477 http://dx.doi.org/10.1120/jacmp.v17i2.5951 |
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