Title

Analytical modelling and simulation of single and double cone pinholes for real-time in-body tracking of an HDR brachytherapy source

RIS ID

108631

Publication Details

Alnaghy, S., Safavi-Naeini, M., Franklin, D. R., Han, Z., Cutajar, D. L., Petasecca, M., Lerch, M. & Rosenfeld, A. B. (2016). Analytical modelling and simulation of single and double cone pinholes for real-time in-body tracking of an HDR brachytherapy source. IEEE Transactions on Nuclear Science, 63 (3), 1375-1385.

Abstract

The choice of pinhole geometry is a critical factor in the performance of pinhole-collimator-based source tracking systems for brachytherapy QA. In this work, an analytical model describing the penetrative sensitivity of a single-cone pinhole collimator to photons emitted from a point source is derived. Using existing models for single-cone resolution and double-cone sensitivity and resolution, the theoretical sensitivity and resolution of the single-cone collimator are quantitatively compared with those of a double-cone collimator with an equivalent field of view. Monte Carlo simulations of the single and double-cone pinhole collimators using an accurate 3D model of a commercial high dose rate brachytherapy source are performed to evaluate the relative performance of each geometry for a novel real-time HDR brachytherapy QA system, HDR BrachyView. The theoretical penetrative sensitivity of the single-cone pinhole is shown to be higher than the double-cone pinhole, which is in agreement with the results from the Monte Carlo simulations. The wider pinhole response function of the single-cone collimator results in a larger total error between the projected center of the source and the estimated center of mass of the source projection for the single-cone collimator, with the greatest error (at the maximum FoV angle) being 0.54 mm for the double-cone pinhole and 1.37 mm for the single-cone at θ = 60°. The double-cone pinhole geometry is determined to be the most appropriate choice for the pinhole collimator in the HDR BrachyView probe.

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Link to publisher version (DOI)

http://dx.doi.org/10.1109/TNS.2016.2540635