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Title: SU-F-T-45: Dosimetric Effects of Saline Filled Balloons During IORT Using Xoft Electronic Brachytherapy

Abstract

Purpose: The portability of Xoft Axxent Electronic Brachytherapy (EBx) System has made it a viable option for intraoperative radiation therapy (IORT) treatment of early-stage breast cancer. The low energy (50kVp) of the X-ray source makes the shielding easy, but also means its dose distribution is sensitive to the medium’s composition. Current treatment planning systems (TPS) typically assume homogenous water for brachytherapy dose calculations, including the pre-calculated atlas plans for the Xoft IORT cases. However, Xoft recommends using saline to fill the balloon applicator. This study investigates the dosimetric difference due to the increased effective atomic number (Zeff) from water (7.42) to saline (7.56). Methods: The diameter of the balloon applicators ranges from 3–6cm, with 4cm being most frequently used. For the 4-cm and 6-cm diameter applicators, MCNP Monte Carlo program was used to calculate the dose at the surface (Ds) of the middle section of the balloon and 1 cm away (D1cm) for water- and saline-filled balloons: one plan with a single dwell at the center and another with multiple dwells as in the atlas plans. The single dwell plan is a simple estimation of the dosimetry, while the atlas plan is representative of the actual dose distribution. Results: Themore » single-dwell plan showed a 5.1% and 6.1% decrease in Ds for the 4- and 6-cm applicators, respectively, due to the saline. The atlas plan showed similar Results: 4.8% and 6.4% decrease, respectively. The decrease in D1cm is 4.3%–5.2% and 3.3%–5.3s% in the single-dwell and atlas plans, respectively, for the 4- and 6-cm applicator. Conclusion: The dosimetric effect introduced by saline is on the order of 5%. This effect should be taken into account during both treatment planning and patient outcome studies.« less

Authors:
; ; ; ; ; ;  [1]
  1. Rush University Medical Center, Chicago, IL (United States)
Publication Date:
OSTI Identifier:
22642294
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; 61 RADIATION PROTECTION AND DOSIMETRY; BRACHYTHERAPY; DOSIMETRY; MAMMARY GLANDS; MONTE CARLO METHOD; NEOPLASMS; PATIENTS; PLANNING; RADIATION DOSE DISTRIBUTIONS; RADIATION SOURCE IMPLANTS; SHIELDING; X-RAY SOURCES

Citation Formats

Redler, G, Templeton, A, Turian, J, Chu, J, Bernard, D, Zhen, H, and Liao, Y. SU-F-T-45: Dosimetric Effects of Saline Filled Balloons During IORT Using Xoft Electronic Brachytherapy. United States: N. p., 2016. Web. doi:10.1118/1.4956180.
Redler, G, Templeton, A, Turian, J, Chu, J, Bernard, D, Zhen, H, & Liao, Y. SU-F-T-45: Dosimetric Effects of Saline Filled Balloons During IORT Using Xoft Electronic Brachytherapy. United States. doi:10.1118/1.4956180.
Redler, G, Templeton, A, Turian, J, Chu, J, Bernard, D, Zhen, H, and Liao, Y. Wed . "SU-F-T-45: Dosimetric Effects of Saline Filled Balloons During IORT Using Xoft Electronic Brachytherapy". United States. doi:10.1118/1.4956180.
@article{osti_22642294,
title = {SU-F-T-45: Dosimetric Effects of Saline Filled Balloons During IORT Using Xoft Electronic Brachytherapy},
author = {Redler, G and Templeton, A and Turian, J and Chu, J and Bernard, D and Zhen, H and Liao, Y},
abstractNote = {Purpose: The portability of Xoft Axxent Electronic Brachytherapy (EBx) System has made it a viable option for intraoperative radiation therapy (IORT) treatment of early-stage breast cancer. The low energy (50kVp) of the X-ray source makes the shielding easy, but also means its dose distribution is sensitive to the medium’s composition. Current treatment planning systems (TPS) typically assume homogenous water for brachytherapy dose calculations, including the pre-calculated atlas plans for the Xoft IORT cases. However, Xoft recommends using saline to fill the balloon applicator. This study investigates the dosimetric difference due to the increased effective atomic number (Zeff) from water (7.42) to saline (7.56). Methods: The diameter of the balloon applicators ranges from 3–6cm, with 4cm being most frequently used. For the 4-cm and 6-cm diameter applicators, MCNP Monte Carlo program was used to calculate the dose at the surface (Ds) of the middle section of the balloon and 1 cm away (D1cm) for water- and saline-filled balloons: one plan with a single dwell at the center and another with multiple dwells as in the atlas plans. The single dwell plan is a simple estimation of the dosimetry, while the atlas plan is representative of the actual dose distribution. Results: The single-dwell plan showed a 5.1% and 6.1% decrease in Ds for the 4- and 6-cm applicators, respectively, due to the saline. The atlas plan showed similar Results: 4.8% and 6.4% decrease, respectively. The decrease in D1cm is 4.3%–5.2% and 3.3%–5.3s% in the single-dwell and atlas plans, respectively, for the 4- and 6-cm applicator. Conclusion: The dosimetric effect introduced by saline is on the order of 5%. This effect should be taken into account during both treatment planning and patient outcome studies.},
doi = {10.1118/1.4956180},
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}
}