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Title: SU-F-T-533: Study of Dosimetric Properties of Cadmium Free Alloy Used in Compensator Based IMRT

Abstract

Purpose: To study the dosimetric properties of cadmium free alloy which is used in compensator based IMRT. Methods: A mixture of 30% of lead,52% of bismuth and 18% of tin was used to prepare alloy. We prepared slabs of different thicknesses ranging from 0.71 cm to 6.14 cm. Density of alloy was measured by Archimedes’ principle using SI-234 Denver instrument and water as buoyant liquid. Transmission, linear attenuation coefficient (µ), tissue phantom ration (TPR), beam hardening, surface dose (Ds), percentage depth dose (PDD) and effect of scatter were measured and analyze for different field size and different thickness of compensator for 6 MV photon beam. Measurements were carried out at 100 cm SSD and 160 cm SSD. Results: Density of alloy was found to be 9.5456 gm/cm3. Melting point of alloy is 90–95 °C. For a field size of 10×10 cm2 µ was 0.4253 cm-1 at 100 cm SSD. Calculated TPR was found to be within 3 % of measured TPR. Ds was found to be decreasing with increasing thickness of compensator. 1cm, 1.98 cm and 4.16 cm thick compensator slab decreased surface dose by 4.2%, 6.1% and 9.5% respectively for a field size of 10×10cm2 at 100 cm SSD.more » As field size increases Ds increases for a given compensator thickness. This is due to increase in amount of scattered dose from wider collimator opening. For smaller field size, PDDs are increased from 3.0% to 5.5% of open beam PDDs as compensator thickness increases from 1 cm to 6.14 cm at a depth of 10 cm in water. For larger field size variation in PDDs is not significant. Conclusion: High degree of modulation can be achieved from this compensator material, which is essential in compensator based IMRT. Dosimetric properties analyzed in this study establish this alloy as a reliable, cost effective, reusable compensator material.« less

Authors:
 [1];  [1];  [2];  [3];  [4]
  1. Dr B L Kapoor Hospital, New Delhi, Delhi (India)
  2. (India)
  3. Guru Jambheshwar University of Science & Technology, Hisar, Haryana (India)
  4. MMH College, Ghaziabad, Utter Pradesh (India)
Publication Date:
OSTI Identifier:
22649116
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 60 APPLIED LIFE SCIENCES; CADMIUM ALLOYS; DEPTH DOSE DISTRIBUTIONS; MELTING POINTS; PHOTON BEAMS; RADIOTHERAPY; THICKNESS; TIN ALLOYS

Citation Formats

Tyagi, A, Kaushik, S, Guru Jambheshwar University of Science & Technology, Hisar, Haryana, Punia, R, and Singh, M. SU-F-T-533: Study of Dosimetric Properties of Cadmium Free Alloy Used in Compensator Based IMRT. United States: N. p., 2016. Web. doi:10.1118/1.4956718.
Tyagi, A, Kaushik, S, Guru Jambheshwar University of Science & Technology, Hisar, Haryana, Punia, R, & Singh, M. SU-F-T-533: Study of Dosimetric Properties of Cadmium Free Alloy Used in Compensator Based IMRT. United States. doi:10.1118/1.4956718.
Tyagi, A, Kaushik, S, Guru Jambheshwar University of Science & Technology, Hisar, Haryana, Punia, R, and Singh, M. Wed . "SU-F-T-533: Study of Dosimetric Properties of Cadmium Free Alloy Used in Compensator Based IMRT". United States. doi:10.1118/1.4956718.
@article{osti_22649116,
title = {SU-F-T-533: Study of Dosimetric Properties of Cadmium Free Alloy Used in Compensator Based IMRT},
author = {Tyagi, A and Kaushik, S and Guru Jambheshwar University of Science & Technology, Hisar, Haryana and Punia, R and Singh, M},
abstractNote = {Purpose: To study the dosimetric properties of cadmium free alloy which is used in compensator based IMRT. Methods: A mixture of 30% of lead,52% of bismuth and 18% of tin was used to prepare alloy. We prepared slabs of different thicknesses ranging from 0.71 cm to 6.14 cm. Density of alloy was measured by Archimedes’ principle using SI-234 Denver instrument and water as buoyant liquid. Transmission, linear attenuation coefficient (µ), tissue phantom ration (TPR), beam hardening, surface dose (Ds), percentage depth dose (PDD) and effect of scatter were measured and analyze for different field size and different thickness of compensator for 6 MV photon beam. Measurements were carried out at 100 cm SSD and 160 cm SSD. Results: Density of alloy was found to be 9.5456 gm/cm3. Melting point of alloy is 90–95 °C. For a field size of 10×10 cm2 µ was 0.4253 cm-1 at 100 cm SSD. Calculated TPR was found to be within 3 % of measured TPR. Ds was found to be decreasing with increasing thickness of compensator. 1cm, 1.98 cm and 4.16 cm thick compensator slab decreased surface dose by 4.2%, 6.1% and 9.5% respectively for a field size of 10×10cm2 at 100 cm SSD. As field size increases Ds increases for a given compensator thickness. This is due to increase in amount of scattered dose from wider collimator opening. For smaller field size, PDDs are increased from 3.0% to 5.5% of open beam PDDs as compensator thickness increases from 1 cm to 6.14 cm at a depth of 10 cm in water. For larger field size variation in PDDs is not significant. Conclusion: High degree of modulation can be achieved from this compensator material, which is essential in compensator based IMRT. Dosimetric properties analyzed in this study establish this alloy as a reliable, cost effective, reusable compensator material.},
doi = {10.1118/1.4956718},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}