- April 2, 2025
- Category: Dose Calculation, Scientific Publications
*Implementation of a Secondary Dose Calculation System for a Magnetic Resonance Linear Accelerator
Methods and Materials:
Relative Dosimetry In Monaco v.5.51.11, fields of 2×2, 5×5, 10×10, 15×15, 20×20, and 2×20 cm² were modeled at gantry 0°, at depths of 5 and 10 cm, in an isocentric configuration to obtain dose profiles and field factors.
Dose in Inhomogeneities In Monaco, the dose was calculated with a 10×10 cm² field and 200 MU in a water-air-water phantom.
MLC Transmission The dose was measured at 5 cm depth using a 10×10 cm² field and 200 MU, with the Exradin® chamber oriented antiparallel to the magnetic field.
Patient-Specific Quality Assurance Five intensity-modulated radiation therapy (IMRT) plans (anal, abdominal, head & neck, prostate, and lung) were measured following AAPM TG-244 guidelines. The measurements were evaluated using the 3.0%/2.0 mm gamma criterion with the ArcCheck®-MR device (SunNuclear, Melbourne, FL, USA).
Results: Relative Dosimetry – Variations of 3.8% were reported for field factors up to 2×2 cm², comparing measured data and Monaco with TQA. MLC Transmission values were 0.25%, 0.60%, and 0.50% for experimental measurements, Monaco, and TQA, respectively. Patient-Specific Quality Assurance and Planning system commissioning were also evaluated.
Conclusion: The TQA software was implemented as a secondary dose calculation system for MR-linac and was clinically validated for adaptive treatment workflow using a 3%/2 mm gamma criterion, with 95% as a tolerance limit and 90% as an action limit.