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Title: Air cavity effects on the radition dose to the larynx using Co-60, 6 MV, and 10 MV photon beams

Abstract

The purpose was to determine the perturbation effect in the surface layers of lesions located in the air-tumor tissues interface of larynx using {sup 60}Co, 6 MV, and 10 MV photon beams. Thermoluminescent dosimeters (TLDs) were embedded at 16 measurement locations in slab no. 8 of a humanoid phantom and exposed to two lateral-opposed beams using standard 7 {times} 7 cm fields. Similarly, radiographic and radiochromic films were placed between slabs no. 7 and no. 8 of the humanoid phantom and exposed to two lateral-opposed radiation beams. The dosimeters were irradiated with {sup 60}Co, 6 MV, and 10 MV photon beams. Computer tomography (CT) treatment planning without inhomogeneity correction was performed. At the tissue-air interface, the average measured percentage dose (% dose{sub m}) is about (108.7 {+-} 4.8%) with TLD data, (96.8 {+-} 2.5%) with radiographic film data, and (100.8 {+-} 4.9%) with radiochromic film data. Similarly, in the central part of the cavity, the % dose{sub m} is (98.4 {+-} 3.1)% with TLD data, (94.3 {+-} 3.3)% with radiographic film data, and (91.7 {+-} 5.0)% with radiochromic film data. Using the CT-based generated dose distribution (without inhomogeneity correction), the average calculated percentage dose (% dose{sub c}) is (98.7 {+-}more » 1.0%) at the tissue-air interface and 98% in the central part of the air cavity. For the beam energies studied, the variation from the % dose {sub m} at the tissue-air interface for a given dosimetry technique is relatively small and therefore should not be significant in clinical settings. The variation from the % dose{sub m} at the tissue-air interface is more significant for lower energies. This variation is about 4.3% for 10 MV photon beam, therefore, while institutional practice favors lower energy ({sup 60}Co to 6 MV) for node-negative glottic cancers, physical/dosimetric evidence offers no disadvantage to the use of higher energy photons. 10 refs., 7 figs., 2 tabs.« less

Authors:
; ; ;  [1]
  1. Georgetown Univ. Medical Center, Washington, DC (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
68511
Resource Type:
Journal Article
Journal Name:
International Journal of Radiation Oncology, Biology and Physics
Additional Journal Information:
Journal Volume: 29; Journal Issue: 5; Other Information: PBD: 30 Jul 1994
Country of Publication:
United States
Language:
English
Subject:
56 BIOLOGY AND MEDICINE, APPLIED STUDIES; PHOTON BEAMS; DOSIMETRY; LARYNX; COBALT 60

Citation Formats

Niroomand-Rad, A, Harter, K W, Thobejane, S, and Bertrand, K. Air cavity effects on the radition dose to the larynx using Co-60, 6 MV, and 10 MV photon beams. United States: N. p., 1994. Web. doi:10.1016/0360-3016(94)90411-1.
Niroomand-Rad, A, Harter, K W, Thobejane, S, & Bertrand, K. Air cavity effects on the radition dose to the larynx using Co-60, 6 MV, and 10 MV photon beams. United States. https://doi.org/10.1016/0360-3016(94)90411-1
Niroomand-Rad, A, Harter, K W, Thobejane, S, and Bertrand, K. 1994. "Air cavity effects on the radition dose to the larynx using Co-60, 6 MV, and 10 MV photon beams". United States. https://doi.org/10.1016/0360-3016(94)90411-1.
@article{osti_68511,
title = {Air cavity effects on the radition dose to the larynx using Co-60, 6 MV, and 10 MV photon beams},
author = {Niroomand-Rad, A and Harter, K W and Thobejane, S and Bertrand, K},
abstractNote = {The purpose was to determine the perturbation effect in the surface layers of lesions located in the air-tumor tissues interface of larynx using {sup 60}Co, 6 MV, and 10 MV photon beams. Thermoluminescent dosimeters (TLDs) were embedded at 16 measurement locations in slab no. 8 of a humanoid phantom and exposed to two lateral-opposed beams using standard 7 {times} 7 cm fields. Similarly, radiographic and radiochromic films were placed between slabs no. 7 and no. 8 of the humanoid phantom and exposed to two lateral-opposed radiation beams. The dosimeters were irradiated with {sup 60}Co, 6 MV, and 10 MV photon beams. Computer tomography (CT) treatment planning without inhomogeneity correction was performed. At the tissue-air interface, the average measured percentage dose (% dose{sub m}) is about (108.7 {+-} 4.8%) with TLD data, (96.8 {+-} 2.5%) with radiographic film data, and (100.8 {+-} 4.9%) with radiochromic film data. Similarly, in the central part of the cavity, the % dose{sub m} is (98.4 {+-} 3.1)% with TLD data, (94.3 {+-} 3.3)% with radiographic film data, and (91.7 {+-} 5.0)% with radiochromic film data. Using the CT-based generated dose distribution (without inhomogeneity correction), the average calculated percentage dose (% dose{sub c}) is (98.7 {+-} 1.0%) at the tissue-air interface and 98% in the central part of the air cavity. For the beam energies studied, the variation from the % dose {sub m} at the tissue-air interface for a given dosimetry technique is relatively small and therefore should not be significant in clinical settings. The variation from the % dose{sub m} at the tissue-air interface is more significant for lower energies. This variation is about 4.3% for 10 MV photon beam, therefore, while institutional practice favors lower energy ({sup 60}Co to 6 MV) for node-negative glottic cancers, physical/dosimetric evidence offers no disadvantage to the use of higher energy photons. 10 refs., 7 figs., 2 tabs.},
doi = {10.1016/0360-3016(94)90411-1},
url = {https://www.osti.gov/biblio/68511}, journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 5,
volume = 29,
place = {United States},
year = {Sat Jul 30 00:00:00 EDT 1994},
month = {Sat Jul 30 00:00:00 EDT 1994}
}