From Digital File to Transferable Phantom: A Dual-Centre Evaluation of Multi-contrast Phantom for Standardized PET Quantification
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Abstract
Background
Three-dimensional printing has been used to build cost effective & realistic phantoms but their adaptability across facilities remains under-explored. Validation of standardization protocols and quantitative metrics of positron emission tomography (PET) to printed phantoms has been sparse. This study aims to evaluate the digital transferability of a multi-contrast phantom design and the quantitative consistency of metrics across two independent facilities, as a foundational step towards multi-centre standardization.
Methods
Cubic phantom inserts (40 mm) featuring spherical targets (0, 10, 15, and 20 mm), of a previously proven design, were fabricated at two different facilities using 3D printing and positioned within a Jaszczak phantom, filled with radiotracer and soap/water solution. Acquisitions (Day 0, 8) were performed on 5-ring Discovery MI and 32 cm OMNI Legend systems. Quantitative metrics, including CT Hounsfield units (HU), PET recovery coefficients (RC) and PET target-to-background ratios (TBR) were statistically analysed (rank sum tests) to assess the influence of facility, scanner model, and acquisition day.
Results
CT images revealed minor differences across facilities and scanners, with notable HU improvement (in emulating water) upon prolonged cube immersion. PET image quality was visually good with respect to desired feature representation. Average TBR Max (mean±std. dev.) were 1.56 ± 0.03 (expected 2.0), 2.35 ± 0.05 (expected 2.5), and 3.10 ± 0.05 (expected 3.33). RC Max and RC Mean ranged from 0.69 – 1.11 and 0.56 - 0.89. No statistical differences were found for TBR Max , RC Mean , or RC Max (p ≥ 0.07 for Mann Whitney; p ≥ 0.57 for Friedman) and Bland-Altman mean bias < 10%.
Conclusion
Our study demonstrates that quantitative PET consistency can be reliably maintained across different facilities, printers, and scanners using 3D-printed phantoms produced from a common digital file. This confirmation of digital transferability offers a crucial and cost-effective framework for standardization, paving the way for more accessible multi-center harmonization studies.
