S1682
Physics - Detectors, dose measurement and phantoms
ESTRO 2026
fields. Aperture collimation substantially reduced the lateral penumbra compared with open PBS, with typical reductions up to ~80% (≈ 8mm) depending on field size and energy. Penumbra increased linearly with air-gap, more steeply at lower energies; moving the RS upstream of the aperture further improved penumbra for selected energies/field sizes. Conclusion: This preliminary characterization demonstrates the feasibility of aperture-collimated PBS for small-field dosimetry. Future work will extend OF measurements across additional energies and depths, integrate aperture modeling into the TPS, assess SOBP configurations, and develop Monte Carlo simulations and a clinical applicator to minimize air-gap effects and enable upstream RS placement. Keywords: small field, detectors, proton Proffered Paper 4223 (M)ADAM: a male–female interchangeable breathing phantom for patient QA Stefania Pallotta 1,2 , Immacolata Vanore 1 , Giacomo Insero 1 , Andrea Profili 3 , Michaela Servi 3 , Yary Volpe 3 , Margherita Zani 2 , Silvia Calusi 2 , Livia Marrazzo 1,2 1 Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Florence, Italy. 2 Medical Physics Unit, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. 3 Department of Industrial Engineering, University of Florence, Florence, Italy Purpose/Objective: The ADAM breathing phantom [1, 2] was upgraded to include a female version, MADAM, featuring a thoracic cavity with breasts and heart. Its dual and interchangeable design enables verification of breast treatments, thereby broadening its potential applications in patient quality assurance (QA) procedures.In this work, we demonstrate the MADAM’s breathing repeatability and a potential application for dose comparison. Material/Methods: (M)ADAM is a 3D-printed phantom of a human torso with embedded ribs and spinal cord, designed for 4D imaging, dose delivery and tracking, and evaluation of gating and tracking devices for moving lesions. The female version (Fig.1) includes breasts of interchangeable shapes and sizes, as well as a realistically shaped heart. The infill density of the breasts was selected to simulate the electron density of human breast tissue. The breasts, chest, and heart are sectioned to accommodate a radiochromic film in a plane orthogonal to the treatment couch. By combining this sectioning with vertical respiratory motion driven by two synchronized motors, MADAM
allows direct comparison between planned and measured doses in the transverse plane.An Arduino programmable board allows the selection of several respiratory signals, including free breathing (FB) and deep inspiration breath hold (DIBH) signals.The repeatability of the phantom’s motion was tested using laser triangulation sensors with 1 µm accuracy and 25 Hz data sampling, which recorded the motor steps over a 15-minute period for each breathing signal (Fig.1c).As a representative use case, 3DCRT treatment (40 Gy in 15 fractions, tangential beams) was delivered to the left breast.
Results: Laser data acquisition demonstrates both temporal and spatial repeatability in MADAM’s motion, with measured standard deviations of less than 0.02 s and 0.08 mm, respectively, for all the six tested signals (Fig.
2). The measured isodoses registered on the CT axial slice (Fig.1b) successfully overlap with the breast PTV, demonstrating a reliable reconstruction of the dose distribution using radiochromic films. Moreover, film shows maximum dose to the heart < 80 cGy, in agreement with TPS, allowing future studies on heart dose variation where the breathing patterns between planning and irradiation differ. Conclusion: (M)ADAM represents a major upgrade of the ADAM phantom, supporting both FB and DIBH signals and enabling future tests on surface and 4D-tracking devices, including those used for breast treatments. Its ability to replicate any respiratory pattern makes (M)ADAM a versatile, professional, and cost-effective multipurpose phantom for comprehensive end-to-end patient QA. References: [1] Pallotta, Stefania, et al. "ADAM phantom to test 4D medical imaging and dose delivery devices." Physics in Medicine & Biology 64.10 (2019): 105002.[2] Pallotta, Stefania, et al. "ADAM: A breathing phantom for lung SBRT quality assurance." Physica Medica 49 (2018): 147-155. Keywords: phantom, breast, quality assurance
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