Monaco tps

A beam model was developed by the vendor Elekta in the Monaco TPS (v.5.09.06) using the commissioned beam data of a clinical 6 MV Agility linac in our center. The beam model uses a virtual source model for simulating the linac head. The beam model parameters are the same for both the XVMC and GPUMCD codes (the two Monaco MC codes differ only in the radiation transport calculations within the patient). These are the parameters for modeling the distribution of primary and scattered photons, as well as secondary charged particles in the MC simulation of the linac head. It also includes nominal beam energy and off‐axis profiles. There are quite a large number of parameters in the list provided by the vendor and may not be relevant for the paper. Tighter criteria (2% or 2 mm in high gradient [30%/cm] region, 2% elsewhere in the percent depth dose [PDD] and beam profiles, and 2% in output factors for homogeneous water medium) than the requirements of the Van Dyk criteria⁽¹⁸⁾ for matching the calculated data with the measured commissioned data was used by the vendor. The phantom size, dose calculation grid resolution, and the statistical uncertainty used by the vendor were in accordance with the recommendations of AAPM TG‐105.⁽⁹⁾

The above film dose measurements were compared against counterpart dose calculations produced by a CMS XiO (v. 4.62) treatment planning system (TPS) for 6 and 15 MV photon beams for the single AP fields of 3 × 3, 5 × 5, 10 × 10, and 15 × 15 cm². Prior to this, the phantom was CT‐scanned with a Toshiba Aquilion^TM 16LB CT scanner after which the DICOM images were imported into the TPS. A superposition algorithm was used for dose calculation employing a grid size of 2.0 mm.
Dose distributions for the two 6 and 15 MV parallel opposed pairs described in section II C were also calculated. In this case, an Elekta Monaco TPS utilizing the X‐ray voxel Monte Carlo (XVMC) (v. 5.00.00) algorithm was used for dose calculations. The treatment plans were generated for the pelvic phantom with inserted film and delivered on the linac. The field size was set to conform to a target contoured on the DICOM images of the phantom. The Monaco TPS calculated dose distributions were then compared to those measured with film in the pelvic phantom that contains the prosthesis. The relative errors (δ) between film measurements and TPS calculations were computed as follows. $\mathit{\delta }=[(D_{Film}-D_{TPS})/D_{Film}]\times 100$

The 6FFF beam modality on Elekta’s VersaHD^TM linear accelerator (linac) with Integrity 4.0.4 control software, was fully commissioned and the corresponding beam model validated in Elekta’s Monaco® TPS, version 5.11.02.⁸ Beam tuning, MLC calibration, and MLC beam modeling in Monaco® were performed according to Elekta’s recommended procedure, taking into account most recent findings.⁹ Performance of these procedures was well within required specifications. MLC parameters in Monaco® were fine‐tuned to achieve optimal agreement for point dose measurement and dose distribution for a range of VMAT and dynamic conformal arc therapy (DCAT) plans.¹⁰ However, clinical VMAT plans still showed unacceptably low pass rates on the VersaHD^TM linac, especially for highly modulated fields and small targets. SunNuclear’s ArcCheck^TM was used for these measurements.

Ten previously treated patients with a variety of treatment sites were randomly selected for dose recalculation using our in‐house Monte Carlo model, which utilized the BEAMnrc/DOSXYZnrc user codes.³⁰, ³¹, ³² The patient cohort consisted of three head‐and‐neck cancer patients, three lung cancer patients, two gynecological cancer patients, and two prostate cancer patients. All patients were treated with 6‐MV VMAT photon beams, and each plan consisted of two arcs. Table 1 presents an overview of the patient cohort, including their assigned identifier. Each patient's plan was created in the Philips Pinnacle TPS, and the dose was initially calculated using the Collapsed Cone Convolution Superposition algorithm. The DICOM RP and DICOM RS (DICOM Version 3) files were exported to Elekta's Monaco TPS, and the dose was recalculated using the Monte Carlo algorithm in Monaco, with the dose‐to‐medium reported. All calculations in Pinnacle and Monaco were done with a 0.3 cm × 0.3 cm × 0.3 cm dose grid resolution. Doses calculated with Monaco's Monte Carlo algorithm were to be used for comparison with our in‐house Monte Carlo algorithm. Both the Pinnacle TPS and Monaco TPS have been previously verified for accuracy.³³, ³⁴ Patients’ DICOM RP files (files containing plan information), RD files (files containing dose information), and CT datasets were exported from the Pinnacle TPS.