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Title: SU-F-T-568: QA of a Multi-Target Multi-Dose VMAT SRS

Abstract

Purpose: To, experimentally, corroborated the prescribed doses utilizing dosimeters (e.g. films and TLDs) that can provide high spatial resolution, allow dose measurement of multiple targets at once, and provide accurate dosimetric results. Methods: A single-isocenter 6FFF SRS VMAT plan consisting of one 358° arc at 0° couch angle and four 179° arcs at 30°, 60°, 330° and 300° couch angles respectively, was generated in ECLIPSE v.11 using a Rando-Alderson anthropomorphic head phantom CT study. This plan was a reproduction of a clinical plan generated for a stage-IV melanoma patient diagnosed with 19 intracranial lesions. The phantom was loaded with axially mounted (between phantom slabs) Gafchromic EBT3 film and TLDs strategically positioned within various target volumes. Film and TLDS were calibrated according to established protocols. Target prescription doses were 16 Gy (3cc≤, 3 lesions), 18 Gy (∼1–3cc, 10 lesions) and 20 Gy (≤1cc, 6 lesions). Phantom setup was verified through CBCT imaging prior to irradiation. Gafchromic films were scanned in transmission mode and TLDs were read, respectively, ∼24 hrs after irradiation. Results: Dose calibrated Gafchromic film data were compared to the ECLIPSE calculated data using a 3% / 3mm gamma function analysis. Results for the gamma values were 96–99% in agreementmore » with the calculated data and with 84–90% of the film pixels within the 3% dose difference. TLD data showed a dose difference of 0.4–8% while the film data for those same locations yielded a difference of 0.4–4%. It was observed that the highest dose discrepancies correlated with the location of the small volume targets. Conclusion: Overall this study corroborated that a VMAT SRS treatment, employing various treatment table rotations and arcs, to multiple intracranial lesions with multiple dose prescriptions can be delivered accurately with the existing radiotherapy technology.« less

Authors:
;  [1];  [2]
  1. University of California, Irvine, Orange, CA (United States)
  2. Clinica Aliada contra el Cancer, Lima (Peru)
Publication Date:
OSTI Identifier:
22649143
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; BIOMEDICAL RADIOGRAPHY; COMPUTERIZED TOMOGRAPHY; PHANTOMS; RADIATION DOSES; RADIOTHERAPY; SPATIAL RESOLUTION

Citation Formats

Roa, D, Kuo, J, and Gonzales, A. SU-F-T-568: QA of a Multi-Target Multi-Dose VMAT SRS. United States: N. p., 2016. Web. doi:10.1118/1.4956753.
Roa, D, Kuo, J, & Gonzales, A. SU-F-T-568: QA of a Multi-Target Multi-Dose VMAT SRS. United States. doi:10.1118/1.4956753.
Roa, D, Kuo, J, and Gonzales, A. Wed . "SU-F-T-568: QA of a Multi-Target Multi-Dose VMAT SRS". United States. doi:10.1118/1.4956753.
@article{osti_22649143,
title = {SU-F-T-568: QA of a Multi-Target Multi-Dose VMAT SRS},
author = {Roa, D and Kuo, J and Gonzales, A},
abstractNote = {Purpose: To, experimentally, corroborated the prescribed doses utilizing dosimeters (e.g. films and TLDs) that can provide high spatial resolution, allow dose measurement of multiple targets at once, and provide accurate dosimetric results. Methods: A single-isocenter 6FFF SRS VMAT plan consisting of one 358° arc at 0° couch angle and four 179° arcs at 30°, 60°, 330° and 300° couch angles respectively, was generated in ECLIPSE v.11 using a Rando-Alderson anthropomorphic head phantom CT study. This plan was a reproduction of a clinical plan generated for a stage-IV melanoma patient diagnosed with 19 intracranial lesions. The phantom was loaded with axially mounted (between phantom slabs) Gafchromic EBT3 film and TLDs strategically positioned within various target volumes. Film and TLDS were calibrated according to established protocols. Target prescription doses were 16 Gy (3cc≤, 3 lesions), 18 Gy (∼1–3cc, 10 lesions) and 20 Gy (≤1cc, 6 lesions). Phantom setup was verified through CBCT imaging prior to irradiation. Gafchromic films were scanned in transmission mode and TLDs were read, respectively, ∼24 hrs after irradiation. Results: Dose calibrated Gafchromic film data were compared to the ECLIPSE calculated data using a 3% / 3mm gamma function analysis. Results for the gamma values were 96–99% in agreement with the calculated data and with 84–90% of the film pixels within the 3% dose difference. TLD data showed a dose difference of 0.4–8% while the film data for those same locations yielded a difference of 0.4–4%. It was observed that the highest dose discrepancies correlated with the location of the small volume targets. Conclusion: Overall this study corroborated that a VMAT SRS treatment, employing various treatment table rotations and arcs, to multiple intracranial lesions with multiple dose prescriptions can be delivered accurately with the existing radiotherapy technology.},
doi = {10.1118/1.4956753},
journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 43,
place = {United States},
year = {2016},
month = {6}
}