S1688
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
1).
in radiotherapy research. In particular, high resolution photopolymer printing enables the fabrication of structures with realistic anatomical detail and reproducible radiological properties. This study investigated the characterization of PolyJet-printed materials to support the development of realistic phantoms for radiotherapy applications. Material/Methods: Cubic samples (60x60x 50 mm3) were designed and printed with for the J850 Digital Anatomy printer1 using five materials, including soft and rigid formulations. For each material, a CT scan (Siemens SOMATOM Definition Flash, Erlangen, Germany) was performed to determine Hounsfield Units (HU), and 1.5T MRI (Siemens Somatom Sola (Siemens Healthineers Erlangen, Germany) was acquired to measure T1 and T2 relaxation times for materials producing detectable signal. Another CT scan (Siemens NAEOTOM Alpha, Forchheim, Germany) was conducted on the highest- and lowest-density samples to derive relative electron density (RED) values. The elastic behavior of a soft material was further evaluated using a 50%-scaled abdominal phantom incorporating organ models of the liver, kidneys, pancreas, spleen, and bone. The phantom was subjected to controlled membrane compression, and CBCT imaging at three compression stages was used to quantify deformation and subsequent relaxation behavior.
Conclusion: Profiles measured with the CMOS detector were comparable to water tank measurements acquired using established solid-state detectors suited for small field dosimetry. These results indicate that the CMOS detector and RW3 phantom are a viable substitute for small field profile measurement in a water tank, with faster setup time. References: C J Stepanek, J A Haynes, S Fletcher. (2023) Evaluation of a complementary metal oxide semiconductor detector as a tool for stereotactic body radiotherapy plan quality assurance. Physics and Imaging in Radiation Oncology Keywords: Small Fields, Dosimetry, Quality Assurance Digital Poster Highlight 4529 Characterization of PolyJet 3D-printed materials for developing dynamic anthropomorphic phantoms in radiotherapy Armin Runz 1,2 , Raquel Figueiredo Augusto 1,2 , Sukanja Santhireswaran 1,2 , Wibke Johnen 1 , Anahita Bakhtiari Moghaddam 1 1 Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany, DKFZ, Heidelberg, Germany. 2 National Center for Radiation Research in Oncology, HIRO, Heidelberg, Germany Purpose/Objective: 3D printing has become an increasingly valuable technique for developing anthropomorphic phantoms
Results: Measured HU values showed good agreement with the manufacturer’s reference2 data. The materials spanned a range from approximately -30 HU (TissueMatrix) to 650 HU (RadioMatrix), covering soft tissue to bone equivalent attenuation, figure 2. Incorporating TissueMatrix in material blends effectively reduced overall HU values, enabling the simulation of lower-density soft tissues, while increasing the proportion of RadioMatrix produced higher-density, bone-equivalent regions. Photon counting CT derived relative electron densities (RED) were 1.0075 for the low-density and 1.2497 for the high-density materials. MRI signal was observed only in the softer materials (TissueMatrix, GelMatrix, SUP706), which exhibited distinct T1 and T2 relaxation times. Mechanical testing demonstrated reproducible
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