Two new DOSXYZnrc sources for 4D Monte Carlo simulations of continuously variable beam configurations, with applications to RapidArc, VMAT, TomoTherapy and CyberKnife

Lobo, Julio; Popescu, I. Antoniu

doi:10.1088/0031-9155/55/16/s01

Cited by 63 publications

(46 citation statements)

References 26 publications

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“…The dose distribution discrepancy introduced between the discretized plan and the continuous delivery was assessed by incorporating DynaLog files into MC simulations for RapidArc QA [6]. For that work, a new DOSXYZnrc source [15] was used to compute the dose distribution, by considering a continuous variable beam configuration, through sampling-based methods. This approach reached simulation times for routine clinical applications, although the required statistical uncertainty was only ensured in the high dose voxels.…”

Section: Introductionmentioning

confidence: 99%

3D VMAT Verification Based on Monte Carlo Log File Simulation with Experimental Feedback from Film Dosimetry

et al. 2016

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A model based on a specific phantom, called QuAArC, has been designed for the evaluation of planning and verification systems of complex radiotherapy treatments, such as volumetric modulated arc therapy (VMAT). This model uses the high accuracy provided by the Monte Carlo (MC) simulation of log files and allows the experimental feedback from the high spatial resolution of films hosted in QuAArC. This cylindrical phantom was specifically designed to host films rolled at different radial distances able to take into account the entrance fluence and the 3D dose distribution. Ionization chamber measurements are also included in the feedback process for absolute dose considerations. In this way, automated MC simulation of treatment log files is implemented to calculate the actual delivery geometries, while the monitor units are experimentally adjusted to reconstruct the dose-volume histogram (DVH) on the patient CT. Prostate and head and neck clinical cases, previously planned with Monaco and Pinnacle treatment planning systems and verified with two different commercial systems (Delta4 and COMPASS), were selected in order to test operational feasibility of the proposed model. The proper operation of the feedback procedure was proved through the achieved high agreement between reconstructed dose distributions and the film measurements (global gamma passing rates > 90% for the 2%/2 mm criteria). The necessary discretization level of the log file for dose calculation and the potential mismatching between calculated control points and detection grid in the verification process were discussed. Besides the effect of dose calculation accuracy of the analytic algorithm implemented in treatment planning systems for a dynamic technique, it was discussed the importance of the detection density level and its location in VMAT specific phantom to obtain a more reliable DVH in the patient CT. The proposed model also showed enough robustness and efficiency to be considered as a pre-treatment VMAT verification system.

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Section: Introductionmentioning

confidence: 99%

3D VMAT Verification Based on Monte Carlo Log File Simulation with Experimental Feedback from Film Dosimetry

et al. 2016

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“…The modulated realistic beams from the Varian TrueBeam accelerator with a Millennium 120 multileaf collimator (MLC) have been simulated by using BEAMnrc/DOSXYZnrc codes and calculated dose distributions have been validated 25, 26, 27…”

Section: Methodsmentioning

confidence: 99%

“…The jaw openings and MLC modulations are modeled in detail in the simulations as described in the study by Lobo and Popescu 27. The typical source phase‐space file for each beam energy used for simulation is about 20 GB in size containing about 900 million particles.…”

Section: Methodsmentioning

confidence: 99%

A simple technique to improve calculated skin dose accuracy in a commercial treatment planning system

Wang

Cmelak

Ding

2018

J Applied Clin Med Phys

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Radiation dermatitis during radiotherapy is correlated with skin dose and is a common clinical problem for head and neck and thoracic cancer patients. Therefore, accurate prediction of skin dose during treatment planning is clinically important. The objective of this study is to evaluate the accuracy of skin dose calculated by a commercial treatment planning system (TPS). We evaluated the accuracy of skin dose calculations by the anisotropic analytical algorithm (AAA) implemented in Varian Eclipse (V.11) system. Skin dose is calculated as mean dose to a contoured structure of 0.5 cm thickness from the surface. The EGSnrc Monte Carlo (MC) simulations are utilized for the evaluation. The 6, 10 and 15 MV photon beams investigated are from a Varian TrueBeam linear accelerator. The accuracy of the MC dose calculations was validated by phantom measurements with optically stimulated luminescence detectors. The calculation accuracy of patient skin doses is studied by using CT based radiotherapy treatment plans including 3D conformal, static gantry IMRT, and VMAT treatment techniques. Results show the Varian Eclipse system underestimates skin doses by up to 14% of prescription dose for the patients studied when external body contour starts at the patient's skin. The external body contour is used in a treatment planning system to calculate dose distributions. The calculation accuracy of skin dose with Eclipse can be considerably improved to within 4% of target dose by extending the external body contour by 1 to 2 cm from the patient's skin. Dose delivered to deeper target volumes or organs at risk are not affected. Although Eclipse treatment planning system has its limitations in predicting patient skin dose, this study shows the calculation accuracy can be considerably improved to an acceptable level by extending the external body contour without affecting the dose calculation accuracy to the treatment target and internal organs at risk. This is achieved by moving the calculation entry point away from the skin.

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“…The 4DdefDOSXYZnrc code is an altered version of the EGSnrc [3] user code defDOSXYZnrc, where dose deposition is tracked in a deformed anatomy without altering the voxel grid [4,5]. It makes use of the source 20 of DOSXYZnrc for simulation of continuously varying beam configurations [6]. The 4DdefDOSXYZnrc user code samples a new geometry for each incident particle, which enables simulation of a continuously moving anatomy.…”

Section: Workflow For Four-dimensional Monte Carlomentioning

confidence: 99%

Automated four-dimensional Monte Carlo workflow using log files and real-time motion monitoring

Sibolt¹,

Cronholm

Heath

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. With emerging techniques for tracking and gating methods in radiotherapy of lung cancer patients, there is an increasing need for efficient four-dimensional Monte Carlo (4DMC) based quality assurance (QA). An automated and flexible workflow for 4DMC QA, based on the 4DdefDOSXYZnrc user code, has been developed in python. The workflow has been tested and verified using an in-house developed dosimetry system comprised of a dynamic thorax phantom constructed for plastic scintillator dosimetry. The workflow is directly compatible with any treatment planning system and can also be triggered by the appearance of linac log files. It has minimum user interaction and, with the use of linac log files, it provides a method for verification of the actually delivered dose in the patient geometry.

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Two new DOSXYZnrc sources for 4D Monte Carlo simulations of continuously variable beam configurations, with applications to RapidArc, VMAT, TomoTherapy and CyberKnife

Cited by 63 publications

References 26 publications

3D VMAT Verification Based on Monte Carlo Log File Simulation with Experimental Feedback from Film Dosimetry

3D VMAT Verification Based on Monte Carlo Log File Simulation with Experimental Feedback from Film Dosimetry

A simple technique to improve calculated skin dose accuracy in a commercial treatment planning system

Automated four-dimensional Monte Carlo workflow using log files and real-time motion monitoring

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