KEY POINTS
- The correspondence addresses radiotherapy applications of three-dimensional printing including patient-specific bolus, immobilization, dosimetry phantoms, proton range modulators, and experimental support devices.
- Locally manufactured objects can vary because of printer model, filament batch, slicer configuration, infill, layer height, print orientation, post-processing, and CT protocol, potentially affecting both geometry and radiological properties.
- The authors highlight a recent multicentre audit involving 10 institutions printing three standardized cuboid objects. Despite nominally identical designs, CT numbers differed by as much as 200 HU and mass density by 0.2 g/cm³.
- Dosimetric validation measurements nevertheless remained within two standard deviations of the respective inter-centre means, suggesting reasonable dose behavior despite measurable material differences.
- Current radiotherapy 3D-printing QA remains heterogeneous, combining caliper measurements, CT evaluation, material characterization, dosimetric testing, and centre-specific reproducibility criteria.
- The authors propose an international repository containing printer model, material, slicer settings, geometric measurements, CT characteristics, density, dosimetry results, and longitudinal stability information.
- The paper is a correspondence and did not undergo the journal’s formal review process; the proposed repository and standardization strategy should therefore be viewed as an implementation recommendation rather than validated consensus guidance.
CLINICAL TAKEAWAY
A 3D-printed bolus, phantom, or range modulator cannot be assumed equivalent simply because the same STL file was used. Centres implementing clinical 3D printing need material-specific commissioning, reproducibility testing, and traceable QA; international shared datasets could eventually make those standards comparable.