An investigation into the use of MMCTP to tune accelerator source parameters and testing its clinical application

Abstract

This paper presents an alternative method to tune Monte Carlo electron beam parameters to match measured data using a minimal set of variables in order to reduce the model setup time prior to clinical implementation of the model. Monte Carlo calculations provide the possibility of a powerful treatment planning verification technique. The nonstandardized and nonautomated process of tuning the required accelerator model is one of the reasons for delays in the clinical implementation of Monte Carlo techniques. This work aims to establish and verify an alternative tuning method that can be carried out in a minimal amount of time, allowing it to be easily implemented in a clinical setting by personnel with minimal experience with Monte Carlo methods. This tuned model can then be incorporated into the MMCTP system to allow the system to be used as a second dose calculation check for IMRT plans. The technique proposed was used to establish the primary electron beam parameters for accelerator models for the Varian Clinac 2100 6 MV photon beam using the BEAMnrc Monte Carlo system. The method is intended to provide a clear, direct, and efficient process for tuning an accelerator model using readily available clinical quality assurance data. The tuning provides a refined model, which agrees with measured dose profile curves within 1.5% outside the penumbra or 3 mm in the penumbra, for square fields with sides of 3 cm up to 30 cm. These models can then be employed as the basis for Monte Carlo recalculations of dose distributions, using the MMCTP system, for clinical treatment plans, providing an invaluable assessment tool. This was tested on six IMRT plans and compared to the measurements performed for the pretreatment QA process. These Monte Carlo values for the average dose to the chamber volume agreed with measurements to within 0.6%.PACS number: 87.55.km

A Monte Carlo study of the effect of an ultrasound transducer on surface dose during intrafraction motion imaging for external beam radiation therapy

“…These voxelized geometries, or MC phantoms, can be based on DICOM images, or user defined material and geometry. The McGill Monte Carlo treatment planning software (MMCTP Version 9.1.1) was employed for the comparison and analysis of dose distributions from a clinical treatment planning system (TPS) with MC dose calculations (using BEAMnrc and DOSXYZnrc) …”

Monte Carlo investigation of collapsed versus rotated IMRT plan verification

“…Monte Carlo simulations were submitted to a remote cluster. Previous tuning (21) provided a refined BEAMnrc linear accelerator model that agreed with measured dose profile curves to an accuracy of within 2% or 3 mm for square fields with sides of 3 cm up to 30 cm and within 1% for the output factors for field sizes of , , , , and . The initial electron energy and FWHM of the radius of the initial electron beam incident on the target was varied to find the percentage depth dose, dose profile curves, and output factors that match the hospital‐measured data, providing output factors that match within 1% of measured output factor values.…”

3D Monte Carlo dosimetry of intraoperative electron radiation therapy (IOERT)

“…The properties of the initial electron beam are the energy spectrum and the full width at half maximum (FWHM) of the Gaussian source. In the literature, it is noted that the common way for the tuning process for conventional accelerators is to iteratively change the values of the mean energy and FWHM [19,20]. Using approach of Laccarino et al [21], the tuning approach was done by calculating PDDs using mono-energetic electrons ranging from 1 MeV up to 13 MeV with a step of 0.5 MeV.…”