Update of the CLRP eye plaque brachytherapy database for photon-emitting sources

TL;DR

This paper updates the CLRP eye plaque brachytherapy database with new 3D dose distributions for various plaques and isotopes, improving accuracy and supporting model-based dose evaluations in ocular brachytherapy.

Contribution

The paper introduces an extended, validated database of 3D dose distributions for eye plaques using egs_brachy, covering new plaque models and isotopes, enhancing dose calculation accuracy.

Findings

Validated dose distributions against previous data and published results.

Provided open access to comprehensive 3D dose datasets.

Supported adoption of model-based dose evaluations in clinical practice.

Abstract

Purpose: To update and extend the Carleton Laboratory for Radiotherapy Physics (CLRP) Eye Plaque (EP) dosimetry database for low-energy photon-emitting brachytherapy sources using egs_brachy, an open-source EGSnrc application. The previous database, CLRP_EPv1, contained datasets for the Collaborative Ocular Melanoma Study (COMS) plaques (2008). The new database, CLRP EPv2, consists of newly-calculated 3D dose distributions for 17 plaques [8 COMS, 5 Eckert & Ziegler BEBIG, and 4 other representative models] for Pd-103, I-125, and Cs-131 seeds. Methods: Plaque models are developed with egs_brachy, based on published/manufacturer dimensions and material data. The BEBIG plaques are identical in dimensions to COMS plaques but differ in elemental composition and/or density. Eye plaques and seeds are simulated at the centre of full-scatter water phantoms, scoring in (0.05 cm)^3 voxels spanning the eye for scenarios: (i) HOMO: simulated TG43 conditions; (ii) HETERO: eye plaques and seeds fully modelled; (iii) HETsi (BEBIG only): one seed is active at a time with other seed geometries present but not emitting photons (inactive). For validation, doses are compared to those from CLRP_EPv1 and published data. Data Format and Access: Data are available at https://physics.carleton.ca/ clrp/eye_plaque_v2, http://doi.org/10.22215/clrp/EPv2. The data consist of 3D dose distributions (text-based EGSnrc 3ddose file) and graphical presentations of the comparisons to previously published data. Potential Applications: The CLRP EPv2 database provides accurate reference 3D dose distributions to advance ocular brachytherapy dose evaluations. The fully-benchmarked eye plaque models will be freely-distributed with egs brachy, supporting adoption of model-based dose evaluations as recommended by TG-129, TG-186, and TG-221.