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Title: SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials

Abstract

Purpose: High-density materials used in dental restoration can cause significant localized dose enhancement due to electron backscatter in head-and-neck radiotherapy, increasing the risk of mucositis. The materials used in prosthetic dentistry have evolved in the last decades from metal alloys to ceramics. We aim to determine the dose enhancement caused by backscatter from currently-used dental materials. Methods: Measurements were performed for three different dental materials: lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}), zirconium dioxide (ZrO{sub 2}), and gold alloy. Small thin squares (2×2×0.15 cm{sup 3}) of the material were fabricated, and placed into a phantom composed of tissue-equivalent material. The phantom was irradiated with a single 6 MV photon field. A thin-window parallel-plate ion chamber was used to measure the dose at varying distances from the proximal interface between the material and the plastic. Results: The dose enhancement at the interface between the high-density and tissue-equivalent materials, relative to a homogeneous phantom, was 54% for the gold alloy, 31% for ZrO{sub 2}, and 9% for Li{sub 2}Si{sub 2}O{sub 5}. This enhancement decreased rapidly with distance from the interface, falling to 11%, 5%, and 0.5%, respectively, 2 mm from the interface. Comparisons with the modeling of this effect in treatment planning systemsmore » are performed. Conclusion: While dose enhancement due to dental restoration is smaller with ceramic materials than with metal alloys, it can still be significant. A spacer of about 2–3 mm would be effective in reducing this enhancement, even for metal alloys.« less

Authors:
; ;  [1]; ; ;  [2]
  1. Brigham and Women’s Hospital / Harvard Medical School, Boston, MA (United States)
  2. Harvard School of Dental Medicine, Boston, MA (United States)
Publication Date:
OSTI Identifier:
22649019
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:
60 APPLIED LIFE SCIENCES; 62 RADIOLOGY AND NUCLEAR MEDICINE; ANIMAL TISSUES; BIOLOGICAL RECOVERY; INTERFACES; IONIZATION CHAMBERS; PHANTOMS; RADIATION DOSES; ZIRCONIUM OXIDES

Citation Formats

Hurwitz, M, Margalit, D, Williams, C, Tso, T, Lee, S, and Rosen, E. SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials. United States: N. p., 2016. Web. doi:10.1118/1.4956611.
Hurwitz, M, Margalit, D, Williams, C, Tso, T, Lee, S, & Rosen, E. SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials. United States. doi:10.1118/1.4956611.
Hurwitz, M, Margalit, D, Williams, C, Tso, T, Lee, S, and Rosen, E. Wed . "SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials". United States. doi:10.1118/1.4956611.
@article{osti_22649019,
title = {SU-F-T-426: Measurement of Dose Enhancement Due to Backscatter From Modern Dental Materials},
author = {Hurwitz, M and Margalit, D and Williams, C and Tso, T and Lee, S and Rosen, E},
abstractNote = {Purpose: High-density materials used in dental restoration can cause significant localized dose enhancement due to electron backscatter in head-and-neck radiotherapy, increasing the risk of mucositis. The materials used in prosthetic dentistry have evolved in the last decades from metal alloys to ceramics. We aim to determine the dose enhancement caused by backscatter from currently-used dental materials. Methods: Measurements were performed for three different dental materials: lithium disilicate (Li{sub 2}Si{sub 2}O{sub 5}), zirconium dioxide (ZrO{sub 2}), and gold alloy. Small thin squares (2×2×0.15 cm{sup 3}) of the material were fabricated, and placed into a phantom composed of tissue-equivalent material. The phantom was irradiated with a single 6 MV photon field. A thin-window parallel-plate ion chamber was used to measure the dose at varying distances from the proximal interface between the material and the plastic. Results: The dose enhancement at the interface between the high-density and tissue-equivalent materials, relative to a homogeneous phantom, was 54% for the gold alloy, 31% for ZrO{sub 2}, and 9% for Li{sub 2}Si{sub 2}O{sub 5}. This enhancement decreased rapidly with distance from the interface, falling to 11%, 5%, and 0.5%, respectively, 2 mm from the interface. Comparisons with the modeling of this effect in treatment planning systems are performed. Conclusion: While dose enhancement due to dental restoration is smaller with ceramic materials than with metal alloys, it can still be significant. A spacer of about 2–3 mm would be effective in reducing this enhancement, even for metal alloys.},
doi = {10.1118/1.4956611},
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}
}