23 research outputs found
Intensity modulated arc therapy implementation in a three phase adaptive 18F-FDG-PET voxel intensity-based planning strategy for head-and-neck cancer
Adaptive biological image-guided dose-painting for head-and-neck cancer : from technical feasibility to clinical applications
Influence of the grid size on the dosimetric characteristics of IMRT beams and on overall treatment plans
The effect of the table top modeling on calculations and measurements for the Delta4 phantom
Evaluation of deformable image coregistration in adaptive dose painting by numbers for head-and-neck cancer
Evaluation of uncertainty-based stopping criteria for Monte Carlo calculations of intensity-modulated radiotherapy and arc therapy patient dose distributions
Purpose: To formulate uncertainty-based stopping criteria for Monte Carlo (MC) calculations of intensity-modulated radiotherapy and intensity-modulated arc therapy patient dose distributions and evaluate their influence on MC simulation times and dose characteristics.
Methods and Materials: For each structure of interest, stopping criteria were formulated as follows: sigma(re1) = 95% of the voxels, where sigma(rel) represents the relative statistical uncertainty on the estimated dose, D. The tolerated uncertainty (sigma(rel,tol)) was 2%. The dose limit (D-lim) equaled the planning target volume (PTV) prescription dose or a dose value related to the organ at risk (OAR) planning constraints. An intensity-modulated radiotherapy-lung, intensity-modulated radiotherapy-ethmoid sinus, and intensity-modulated arc therapy-rectum patient case were studied. The PTV-stopping criteria-based calculations were compared with the PTV+OAR-stopping criteria-based calculations.
Results: The MC dose distributions complied with the PTV-stopping criteria after 14% (lung), 21% (ethmoid), and 12% (rectum) of the simulation times of a 100 million histories reference calculation, and increased to 29%, 44%, and 51%, respectively, by the addition of the OAR-stopping criteria. Dose-volume histograms corresponding to the PTV-stopping criteria, PTV+OAR-stopping criteria, and reference dose calculations were indiscernible. The median local dose differences between the PTV-stopping criteria and the reference calculations amounted to 1.4 % (lung), 2.1 % (ethmoid), and 2.5 % (rectum).
Conclusions: For the patient cases studied, the MC calculations using PTV-stopping criteria only allowed accurate treatment plan evaluation. The proposed stopping criteria provided a flexible tool to assist MC patient dose calculations. The structures of interest and appropriate values of sigma(rel,tol) and D-lim should be selected for each patient individually according to the clinical treatment planning goals