A software tool for parametric collimator creation for linac-based preclinical irradiation studies
Abstract
Designing custom Cerrobend collimators for linac-based preclinical electron irradiation is labor intensive and susceptible to design inconsistencies. We developed Collimator Creator (CC), an open source parametric workflow that converts aperture dimensions and jig offsets into printable STL models for a collimator mold, collimator shell, Cerrobend holder, and beam degrader. Two designs were fabricated and characterized: a 4.0 x 1.5 cm2 bilateral lung collimator centered on the central axis and a 1.5 x 1.5 cm2 unilateral lung collimator with a 7.5 mm jig offset, each with a 15 mm thick Cerrobend collimator and a 10 mm PLA degrader. Kilovoltage planar images were used to assess aperture geometry and casting uniformity. Radiochromic film was used to measure full width at half maximum (FWHM) and 80%-20% penumbra under conventional and ultra high dose rate (UHDR) electron delivery on a Varian TrueBeam, and off axis leakage was measured with an ionization chamber at conventional dose rate. The cast Cerrobend apertures deviated by less than 0.2 mm from their specified designs. FWHM values were within 3% of the nominal field dimensions, and penumbra ranged from 0.73 to 1.05 mm under conventional and UHDR delivery. Crossline leakage 2 cm beyond the collimator edge was below 2% for both collimators at conventional dose rate. Parametric collimator generation standardized digital design inputs for the two evaluated rectangular linac-based electron fields. Further work will assess specimen-level dosimetry, additional aperture geometries, and Monte Carlo integration.
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BibTeX
@misc{schulz2026software,
title = {{A software tool for parametric collimator creation for linac-based preclinical irradiation studies}},
author = {Joseph B. Schulz and Dixin Chen and Lloyd Emmanuel Kamole Ghomsi and M. Ramish Ashraf and Lawrie Skinner and Edward Elliot Graves and Billy W. Loo Jr and Stavros Melemenidis},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.06457},
eprint = {2610.06457},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.06457},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A software tool for parametric collimator creation for linac-based preclinical irradiation studies
AU - Joseph B. Schulz
AU - Dixin Chen
AU - Lloyd Emmanuel Kamole Ghomsi
AU - M. Ramish Ashraf
AU - Lawrie Skinner
AU - Edward Elliot Graves
AU - Billy W. Loo Jr
AU - Stavros Melemenidis
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2610.06457
UR - https://arxiv.org/abs/2610.06457
AB - Designing custom Cerrobend collimators for linac-based preclinical electron irradiation is labor intensive and susceptible to design inconsistencies. We developed Collimator Creator (CC), an open source parametric workflow that converts aperture dimensions and jig offsets into printable STL models for a collimator mold, collimator shell, Cerrobend holder, and beam degrader. Two designs were fabricated and characterized: a 4.0 x 1.5 cm^2 bilateral lung collimator centered on the central axis and a 1.5 x 1.5 cm^2 unilateral lung collimator with a 7.5 mm jig offset, each with a 15 mm thick Cerrobend collimator and a 10 mm PLA degrader. Kilovoltage planar images were used to assess aperture geometry and casting uniformity. Radiochromic film was used to measure full width at half maximum (FWHM) and 80%-20% penumbra under conventional and ultra high dose rate (UHDR) electron delivery on a Varian TrueBeam, and off axis leakage was measured with an ionization chamber at conventional dose rate. The cast Cerrobend apertures deviated by less than 0.2 mm from their specified designs. FWHM values were within 3% of the nominal field dimensions, and penumbra ranged from 0.73 to 1.05 mm under conventional and UHDR delivery. Crossline leakage 2 cm beyond the collimator edge was below 2% for both collimators at conventional dose rate. Parametric collimator generation standardized digital design inputs for the two evaluated rectangular linac-based electron fields. Further work will assess specimen-level dosimetry, additional aperture geometries, and Monte Carlo integration.
ER -