skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: SU-F-T-502: FFF Beams, Jaw-Tracking and Treatment Techniques: Out of Field Dose Considerations for Pediatric Radiation Therapy Delivery

Abstract

Purpose: To compare the extended dose profile delivered by 3DCRT and VMAT techniques for flattened and flattening-filter-free(FFF) photon beams (6X, 6XFFF,10XFFF), with and without jaw-tracking (JT) on Varian TrueBeam linac. The goal is to determine which treatment technique/modality will minimize the peripheral photon dose exposure (and ultimately minimize the risk of second malignant neoplasms (SMN)) in pediatric patients. Methods: 3DCRT, VMAT, and jaw tracking VMAT (JTVMAT) plans with 6X, 6XFFF and 10XFFF x-ray beams were created on a 30×60×22.5cm solid water phantom with a 551 cc PTV. The 3DCRT plans consisted of a 4FLD arrangement. The optimization objectives for the single-arc VMAT plans was V95%Rx=98% to PTV and minimize dose to a 5cm diameter organ at risk (OAR). The OAR to PTV distance varied from 0–30cm along the long axis at 7.5cm depth. The dose to the center of the OAR was measured using a 0.6cc ion chamber. Results: Relative to the 6X flattened beam, the 10XFFF photon beam had the lowest dose in the penumbra and peripheral region (>15 cm) region by up to 20% and 40%, respectively for all modalities (3DCRT, VMAT, JTVMAT). The 6XFFF beams only showed a dose reduction in the peripheral region (by up tomore » 20%). JT did not significantly affect the peripheral dose for all modalities and energies. Conclusion: Treating pediatric patients with a 10XFFF beam is the most effective way to reduce photon scatter dose in both the penumbra and peripheral regions. However, the neutron dose contribution resulting from the 10MV beam still needs to be considered. For all modalities, 6XFFF was the next effective method to reduce peripheral photon doses. 3DCRT beams had the lowest peripheral doses for all energies compared to VMAT and JTVMAT, however previous publications have shown that this comes at the expense of PTV conformity and OAR sparing.« less

Authors:
;  [1];  [2]
  1. University of British Columbia, Vancouver, BC (Canada)
  2. (Canada)
Publication Date:
OSTI Identifier:
22649089
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; IONIZATION CHAMBERS; LINEAR ACCELERATORS; MINIMIZATION; PEDIATRICS; PHOTON BEAMS; RADIATION DOSES; RADIOTHERAPY; X RADIATION

Citation Formats

Ben Bouchta, Y, Bergman, A, and Vancouver Cancer Center-British Columbia Cancer Agency, Vancouver, BC. SU-F-T-502: FFF Beams, Jaw-Tracking and Treatment Techniques: Out of Field Dose Considerations for Pediatric Radiation Therapy Delivery. United States: N. p., 2016. Web. doi:10.1118/1.4956687.
Ben Bouchta, Y, Bergman, A, & Vancouver Cancer Center-British Columbia Cancer Agency, Vancouver, BC. SU-F-T-502: FFF Beams, Jaw-Tracking and Treatment Techniques: Out of Field Dose Considerations for Pediatric Radiation Therapy Delivery. United States. doi:10.1118/1.4956687.
Ben Bouchta, Y, Bergman, A, and Vancouver Cancer Center-British Columbia Cancer Agency, Vancouver, BC. Wed . "SU-F-T-502: FFF Beams, Jaw-Tracking and Treatment Techniques: Out of Field Dose Considerations for Pediatric Radiation Therapy Delivery". United States. doi:10.1118/1.4956687.
@article{osti_22649089,
title = {SU-F-T-502: FFF Beams, Jaw-Tracking and Treatment Techniques: Out of Field Dose Considerations for Pediatric Radiation Therapy Delivery},
author = {Ben Bouchta, Y and Bergman, A and Vancouver Cancer Center-British Columbia Cancer Agency, Vancouver, BC},
abstractNote = {Purpose: To compare the extended dose profile delivered by 3DCRT and VMAT techniques for flattened and flattening-filter-free(FFF) photon beams (6X, 6XFFF,10XFFF), with and without jaw-tracking (JT) on Varian TrueBeam linac. The goal is to determine which treatment technique/modality will minimize the peripheral photon dose exposure (and ultimately minimize the risk of second malignant neoplasms (SMN)) in pediatric patients. Methods: 3DCRT, VMAT, and jaw tracking VMAT (JTVMAT) plans with 6X, 6XFFF and 10XFFF x-ray beams were created on a 30×60×22.5cm solid water phantom with a 551 cc PTV. The 3DCRT plans consisted of a 4FLD arrangement. The optimization objectives for the single-arc VMAT plans was V95%Rx=98% to PTV and minimize dose to a 5cm diameter organ at risk (OAR). The OAR to PTV distance varied from 0–30cm along the long axis at 7.5cm depth. The dose to the center of the OAR was measured using a 0.6cc ion chamber. Results: Relative to the 6X flattened beam, the 10XFFF photon beam had the lowest dose in the penumbra and peripheral region (>15 cm) region by up to 20% and 40%, respectively for all modalities (3DCRT, VMAT, JTVMAT). The 6XFFF beams only showed a dose reduction in the peripheral region (by up to 20%). JT did not significantly affect the peripheral dose for all modalities and energies. Conclusion: Treating pediatric patients with a 10XFFF beam is the most effective way to reduce photon scatter dose in both the penumbra and peripheral regions. However, the neutron dose contribution resulting from the 10MV beam still needs to be considered. For all modalities, 6XFFF was the next effective method to reduce peripheral photon doses. 3DCRT beams had the lowest peripheral doses for all energies compared to VMAT and JTVMAT, however previous publications have shown that this comes at the expense of PTV conformity and OAR sparing.},
doi = {10.1118/1.4956687},
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}
}