ESTRO 2025 - Abstract Book

S2609

Physics - Detectors, dose measurement and phantoms

ESTRO 2025

Results: Lung material characterization via CT and 1.5 T MR imaging demonstrated that the PDMS sponges successfully replicated human lung HU values [2] and T1 relaxation times [3]. Material stability was confirmed through reproducibility measurements over six months, with consistent data within a standard deviation (Fig. 1). A 25%-scaled version of the ADAM phantom (MiniADAM, Fig. 2a) was developed. This 3D-printed phantom simulates a male thorax and incorporates a motorized system to compress the lung sponge, mimicking diaphragmatic respiration and moving simulated lesion objects. It also includes a dedicated housing for radiochromic film for dosimetric evaluations. The sponge compressibility, validated through 4D-CT imaging, revealed that the HU variation range across respiratory phases was up to sixfold greater in the compressed sponge compared to the uncompressed one. Notably, the film’s axial plane remained stable throughout the compression process. Furthermore, the intrinsic inhomogeneity of the sponges allowed for the recreation of both healthy and pathological lung morphologies (Figs. 2b, 2c).

Conclusion: This study demonstrates that PDMS sponges effectively replicate lung characteristics and respiratory dynamics. The MiniADAM prototype has proven suitable for the proposed objectives, and future work will focus on developing a full-