A jaw calibration method to provide a homogeneous dose distribution in the matching region when using a monoisocentric beam split technique

Abstract

With this method, we are able to reduce the positioning accuracy to 0.2 mm. Consequently, the dose distribution in the junction of abutted fields is highly smoothed, achieving the maximum dose heterogeneity to be less than 3%.

A method for accurate zero calibration of asymmetric jaws in single-isocenter half-beam techniques

“…The results obtained in this study are similar to those obtained by Cenizo et al 17 with a method based on Monte Carlo simulations. Nevertheless, we have shown that it is possible to derive the relation between the junction dose and V from the dose profile of a single half-beam and the parameter V 1 , which is a simpler and more practical approach.…”

“…Clews and Greer 16 investigated the use of electronic portal imaging devices (EPIDs) for quality assurance of the jaw positioning and reported that there was a need for better calibration methods. Cenizo et al 17 recently proposed a method for an accurate calibration of the zero jaw position, but their method requires complex Monte Carlo simulations and it is not practical to be implemented in clinical practice.…”

Variance-Reduction Methods for Monte Carlo Simulation of Radiation Transport

“…The ant colony method has been proven to be effective in simulations of clinical linear electron accelerators [22,23], in a study of the response of MOSFET dosimeters [24], in dosimetry calculations of radiosurgery treatments [25], in the optimization of certain radiotherapy procedures [26], and in calculations of specific absorption fractions in Nuclear Medicine [20].…”

Calibrating TrueBeam jaws by considering collimator walkout to improve the dose uniformity at abutting field junctions

“…Accurate field sizes and a homogeneous junction dose benefit clinical applications such as mono‐isocentric half‐beam block breast cancer or head and neck cancer treatment with field matching . Junction requirements in the Canadian Partnership for Quality Radiotherapy (CPQR) protocol specify variances in terms of the dosimetry – 5% tolerance and 10% action levels for the dose peak/valley across the junction of the abutting fields – but the reality is this constrains the jaw position's accuracy and precision to be less than half a millimeter . To add to the complexity one often wishes to match jaws that have a 90° collimator rotation between them and the collimator walkout becomes a serious consideration …”