Evaluation of beam matching accuracy among six linacs from the same vendor
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The purpose of this study was to evaluate the dosimetric variation among six non-beam-matched Varian linacs using different techniques for the same plans. Six non-beam-matched Varian machines, comprising two Clinac iX, two 600 C/D (Unique), and two True Beam Tx photon 6 MV X-ray devices were acquired. Sixty patients with of head and neck (H&N; 30) and pelvic (30) treatment sites were chosen. For all 60 patients, three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated radiotherapy (VMAT) plans were generated for the Clinac iX-1 device; all plans were migrated to the remaining machines, using the eclipse treatment planning system without any modification. The dosimetric variation among the six machines for each target volume and organ at risk was recorded and analyzed. In H&N cases, the maximum variation among the six machines with 3DCRT, IMRT, and VMAT was 2.57%, 2.6%, and 2.6%, respectively. In pelvic cases, the maximum variation among the six machines with 3DCRT, IMRT, and VMAT was 2.2%, 1.95%, and 2.05%, respectively. Our overall results show that dosimetric variation, while interchanging the plans among the six machines at phantom and patient levels, remains within the limits of clinical acceptability. The noted variation was not correlated with any of these treatment techniques: 3DCRT, IMRT, or VMAT.
KeywordsNon-beam-matched linacs Re-planning Dosimetric evaluation TPS commissioning Single-beam data
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Statement of human rights
This study has been approved by the appropriate Institutional Review Board (IRB) and has been performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the Institutional Review Board (IRB) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Research involving animals
This study did not use animals for any experiments.
For this type of retrospective study, formal consent is not required in our Institution.
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