Abstract
The purpose of this study is to report the dosimetric aspects of commissioning performed on an Elekta Versa HD linear accelerator (linac) with high‐dose‐rate flattening filter‐free (FFF) photon modes and electron modes. Acceptance and commissioning was performed on the Elekta Versa HD linac with five photon energies (6 MV, 10 MV, 18 MV, 6 MV FFF, 10 MV FFF), four electron energies (6 MeV, 9 MeV, 12 MeV, 15 MeV) and 160‐leaf (5 mm wide) multileaf collimators (MLCs). Mechanical and dosimetric data were measured and evaluated. The measurements include percent depth doses (PDDs), in‐plane and cross‐plane profiles, head scatter factor (Sc), relative photon output factors (Scp), universal wedge transmission factor, MLC transmission factors, and electron cone factors. Gantry, collimator, and couch isocentricity measurements were within 1 mm, 0.7 mm, and 0.7 mm diameter, respectively. The PDDs of 6 MV FFF and 10 MV FFF beams show deeper dmax and steeper falloff with depth than the corresponding flattened beams. While flatness values of 6 MV FFF and 10 MV FFF normalized profiles were expectedly higher than the corresponding flattened beams, the symmetry values were almost identical. The cross‐plane penumbra values were higher than the in‐plane penumbra values for all the energies. The MLC transmission values were 0.5%, 0.6%, and 0.6% for 6 MV, 10 MV, and 18 MV photon beams, respectively. The electron PDDs, profiles, and cone factors agree well with the literature. The outcome of radiation treatment is directly related to the accuracy in the dose modeled in the treatment planning system, which is based on the commissioned data. Commissioning data provided us a valuable insight into the dosimetric characteristics of the beam. This set of commissioning data can provide comparison data to others performing Versa HD commissioning, thereby improving patient safety.PACS number(s): 87.56.bd
Highlights
180 Narayanasamy et al.: Commissioning of Versa HD linac tabulated to provide information
The maximum field size is 40 × 40 cm2, defined by a pair of sculpted diaphragms mounted orthogonal to the multileaf collimator (MLC)
Mechanical tests Using a level placed on the accessory face of the gantry, the largest deviation in digital readout of the gantry and collimator angles was recorded to be 0.2°, which is lower than the 0.5° tolerance
Summary
The purpose of this study is to report the dosimetric aspects of commissioning performed on an Elekta Versa HD linear accelerator with high-dose-rate flattening filter-free (FFF) photon modes and electron modes. The main goal of this work is to generate a set of technical guidelines that may assist other institutions performing a Versa HD commissioning
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