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Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator

Measurements designed to find the collimator backscatter into the beam monitor chamber from Micro Multileaf collimator of 6 MV photon beams of the Siemens Primus linear accelerator were made with the help of dose rate feedback control. The photons and electrons backscattered from the upper and lower...

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Autores principales: Muralidhar, K. R., Murthy, P. Narayana, Sresty, N. V. N. M., Dixit, Pramod Kumar, Kumar, Rajneesh, Raju, A. K.
Formato: Texto
Lenguaje:English
Publicado: Medknow Publications 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000533/
https://www.ncbi.nlm.nih.gov/pubmed/21157537
http://dx.doi.org/10.4103/0971-6203.33243
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author Muralidhar, K. R.
Murthy, P. Narayana
Sresty, N. V. N. M.
Dixit, Pramod Kumar
Kumar, Rajneesh
Raju, A. K.
author_facet Muralidhar, K. R.
Murthy, P. Narayana
Sresty, N. V. N. M.
Dixit, Pramod Kumar
Kumar, Rajneesh
Raju, A. K.
author_sort Muralidhar, K. R.
collection PubMed
description Measurements designed to find the collimator backscatter into the beam monitor chamber from Micro Multileaf collimator of 6 MV photon beams of the Siemens Primus linear accelerator were made with the help of dose rate feedback control. The photons and electrons backscattered from the upper and lower secondary collimator jaws give rise to a significant increase in the ion charge measured by monitor chamber. This increase varies between the different accelerators. The output measurements were carried out in air at the isocenter. The effect of collimator backscatter was investigated by measuring the pulse width, number of beam pulses per monitor unit, monitor unit rate and dose for different mMLC openings. These measurements were made with and without dose rate feedback control, i.e., with constant electron beam current in the accelerator. Monitor unit rate (MU/min) was almost constant for all field sizes. The maximum variation between the open and the closed feedback control circuits was 2.5%. There was no difference in pulse width and negligible difference in pulse frequency. Maximum value of backscattered radiation from the micro Multileaf collimator into the beam monitor chamber was found to be 0.5%.
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spelling pubmed-30005332010-12-14 Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator Muralidhar, K. R. Murthy, P. Narayana Sresty, N. V. N. M. Dixit, Pramod Kumar Kumar, Rajneesh Raju, A. K. J Med Phys Original Article Measurements designed to find the collimator backscatter into the beam monitor chamber from Micro Multileaf collimator of 6 MV photon beams of the Siemens Primus linear accelerator were made with the help of dose rate feedback control. The photons and electrons backscattered from the upper and lower secondary collimator jaws give rise to a significant increase in the ion charge measured by monitor chamber. This increase varies between the different accelerators. The output measurements were carried out in air at the isocenter. The effect of collimator backscatter was investigated by measuring the pulse width, number of beam pulses per monitor unit, monitor unit rate and dose for different mMLC openings. These measurements were made with and without dose rate feedback control, i.e., with constant electron beam current in the accelerator. Monitor unit rate (MU/min) was almost constant for all field sizes. The maximum variation between the open and the closed feedback control circuits was 2.5%. There was no difference in pulse width and negligible difference in pulse frequency. Maximum value of backscattered radiation from the micro Multileaf collimator into the beam monitor chamber was found to be 0.5%. Medknow Publications 2007 /pmc/articles/PMC3000533/ /pubmed/21157537 http://dx.doi.org/10.4103/0971-6203.33243 Text en © Journal of Medical Physics http://creativecommons.org/licenses/by/2.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Article
Muralidhar, K. R.
Murthy, P. Narayana
Sresty, N. V. N. M.
Dixit, Pramod Kumar
Kumar, Rajneesh
Raju, A. K.
Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
title Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
title_full Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
title_fullStr Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
title_full_unstemmed Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
title_short Measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
title_sort measurement of back-scattered radiation from micro multileaf collimator into the beam monitor chamber from a dual energy linear accelerator
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000533/
https://www.ncbi.nlm.nih.gov/pubmed/21157537
http://dx.doi.org/10.4103/0971-6203.33243
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