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Title: SU-E-J-202: Performance of the Patient QA Systems in a Hybrid MRI-Linac

Abstract

Purpose: The first clinical MR-linac will soon become operational, therefore patient plan QA procedures and equipment have to become MRcompatible. Reference dosimetry is affected by the magnetic field, however, relative dosimetry using patient QA systems haven’t been investigated extensively. The purpose of this study was to examine the performance characteristics of the MR-compatible ArcCHECK and Delta4 systems in a transverse 1.5 T magnetic field. Methods: Recently MR-compatible versions of both ArcCheck (Sun Nuclear) and Delta4 (Scandidos) have been developed. To examine the performance characteristics within the magnetic field, the reproducibility, dose linearity, dose rate dependence, field size and angular dependence were evaluated on the MR-linac (8 MV FFF beam, SAD of 142 cm) and a conventional linac (Elekta, 6MV). To allow comparison of the measurements with and without magnetic field, the measurement setup for the conventional linac is adapted to mimic the setup at the MR-linac if possible (e.g. SAD, dose rate). The results from the MR-linac were benchmarked to the results from the conventional linac as being the clinical reference. Results: At the moment of writing, measurements for the Delta4 are still running. Therefore, only the results of the ArcCheck are presented in this abstract. No significant difference wasmore » observed in the reproducibility of the ArcCheck (<0.06%) between both linacs. The maximum dose response difference when measuring the dose linearity was less than 0.4% and the varying dose rate resulted in maximal dose differences of 1.0% for both linacs. Response variation for varying field sizes was <2.6% at the conventional linac, and <1.0% at the MR-linac. Angular response was similar for both linacs. Conclusion: The reproducibility, dose linearity, dose rate dependence, field size and angular dependence of the MR compatible ArcCheck were not influenced by the presence of a transverse 1.5 T magnetic field. The results for the Delta4 are about to follow. Equipment is generously provided by Sun Nuclear Corporation (Melbourne, USA) and Scandidos (Uppsala, Sweden)« less

Authors:
; ; ; ; ; ; ;  [1]
  1. University Medical Center Utrecht, Utrecht (Netherlands)
Publication Date:
OSTI Identifier:
22499306
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 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; BENCHMARKS; DOSE RATES; DOSIMETRY; EQUIPMENT; LINEAR ACCELERATORS; MAGNETIC FIELDS; NMR IMAGING; PATIENTS; QUALITY ASSURANCE; RADIATION DOSES; RADIOTHERAPY; SWEDEN

Citation Formats

Houweling, A, Vries, W de, Wolthaus, J, Woodings, S, Asselen, B van, Kok, J, Lagendijk, J, and Raaymakers, B. SU-E-J-202: Performance of the Patient QA Systems in a Hybrid MRI-Linac. United States: N. p., 2015. Web. doi:10.1118/1.4924288.
Houweling, A, Vries, W de, Wolthaus, J, Woodings, S, Asselen, B van, Kok, J, Lagendijk, J, & Raaymakers, B. SU-E-J-202: Performance of the Patient QA Systems in a Hybrid MRI-Linac. United States. doi:10.1118/1.4924288.
Houweling, A, Vries, W de, Wolthaus, J, Woodings, S, Asselen, B van, Kok, J, Lagendijk, J, and Raaymakers, B. Mon . "SU-E-J-202: Performance of the Patient QA Systems in a Hybrid MRI-Linac". United States. doi:10.1118/1.4924288.
@article{osti_22499306,
title = {SU-E-J-202: Performance of the Patient QA Systems in a Hybrid MRI-Linac},
author = {Houweling, A and Vries, W de and Wolthaus, J and Woodings, S and Asselen, B van and Kok, J and Lagendijk, J and Raaymakers, B},
abstractNote = {Purpose: The first clinical MR-linac will soon become operational, therefore patient plan QA procedures and equipment have to become MRcompatible. Reference dosimetry is affected by the magnetic field, however, relative dosimetry using patient QA systems haven’t been investigated extensively. The purpose of this study was to examine the performance characteristics of the MR-compatible ArcCHECK and Delta4 systems in a transverse 1.5 T magnetic field. Methods: Recently MR-compatible versions of both ArcCheck (Sun Nuclear) and Delta4 (Scandidos) have been developed. To examine the performance characteristics within the magnetic field, the reproducibility, dose linearity, dose rate dependence, field size and angular dependence were evaluated on the MR-linac (8 MV FFF beam, SAD of 142 cm) and a conventional linac (Elekta, 6MV). To allow comparison of the measurements with and without magnetic field, the measurement setup for the conventional linac is adapted to mimic the setup at the MR-linac if possible (e.g. SAD, dose rate). The results from the MR-linac were benchmarked to the results from the conventional linac as being the clinical reference. Results: At the moment of writing, measurements for the Delta4 are still running. Therefore, only the results of the ArcCheck are presented in this abstract. No significant difference was observed in the reproducibility of the ArcCheck (<0.06%) between both linacs. The maximum dose response difference when measuring the dose linearity was less than 0.4% and the varying dose rate resulted in maximal dose differences of 1.0% for both linacs. Response variation for varying field sizes was <2.6% at the conventional linac, and <1.0% at the MR-linac. Angular response was similar for both linacs. Conclusion: The reproducibility, dose linearity, dose rate dependence, field size and angular dependence of the MR compatible ArcCheck were not influenced by the presence of a transverse 1.5 T magnetic field. The results for the Delta4 are about to follow. Equipment is generously provided by Sun Nuclear Corporation (Melbourne, USA) and Scandidos (Uppsala, Sweden)},
doi = {10.1118/1.4924288},
journal = {Medical Physics},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}