Design of an Anthropomorphic 3D-Printed Left Breast Phantom for End-to-End Quality Assurance of Advanced Radiotherapy Techniques In Small Island Developing States
Abstract
Purpose
Breast cancer is the second common malignancy worldwide, with small island developing states (SIDS) experiencing disproportionately higher mortality-to-incidence ratios. Breast treatment planning remains one of the most challenging techniques and is prone to delivery errors. This work aims to design an anthropomorphic, 3D-printed, left breast phantom to facilitate clinically relevant end-to-end testing of advanced radiotherapy deliveries.
Methods
To establish clinical relevance, a five-year retrospective cohort from a SIDS institution was analyzed and commercial breast phantoms were reviewed. In parallel, a systematic review of the clinical impact of residual errors in breast radiotherapy was used to inform phantom development. An anonymized, open-source, left breast DICOM dataset was segmented and converted to STL format then transformed into a solid geometry and subsequently imported into SOLIDWORKS to facilitate detector design. Locations were optimized to correlate film-based distributions to point-dose measurements from ion chambers. Three thermoplastics were also characterized for tissue equivalence.
Results
Analysis of five-year data revealed a mean breast planning target volume (PTV) of 1485.2 ± 442.98 cc comparable to the anonymized dataset PTV 1419.2 cc and significantly different to commercial phantoms - 485cc. Review of residual errors showed significant impact on lung and heart toxicity from treatment displacements. Three thermoplastics were tested: PLA, ABS and DuraForm, with Duraform showing the best agreement to breast tissue ( -131.656 ± 27.878 HU). The phantom assesses breast, tumor bed, axillary and supraclavicular PTV alongside heart and lung.
Conclusion
To our knowledge, this is the first clinically optimized anthropomorphic left breast and nodal volume phantom specifically designed to reflect the anatomical and volumetric features of SIDS breast cancer patients. Its design facilitates quantitative assessment of target, nodal and normal-tissue volumes. This novel device will strengthen radiotherapy QA frameworks in resource-limited settings. Future work includes commissioning and testing across a cohort of SIDS radiotherapy centers.