S1841
Physics - Dose prediction/calculation, optimisation and applications for photon and electron planning
ESTRO 2026
Results: Four left-sided and two right-sided breast cases were analyzed. No clinically significant differences were observed in target coverage, with V95%, V105%, and V107% variations below 1%, and D98% differences <1 Gy. Differences in contralateral breast mean dose and skin hotspots were negligible. For OARs, clinically relevant median dose reductions were observed with the bra setup for the ipsilateral lung and heart: V8 Gy decreased by 4.0% (range: –0.1 to 9.8%) and V1.5 Gy
Bradfield L, Burri SH, Cabrera AR, Cunningham DA. Radiation Therapy for Brain Metastases: An ASTRO Clinical Practice Guideline. Practical Radiation Oncology. 2022;12(4):265-82. Keywords: brain function sparing, brain metastases, SRT Digital Poster 1498 Enhancing breast radiotherapy with an immobilization bra: a prospective dosimetric analysis Valeria Faccenda 1,2 , Riccardo Ray Colciago 2 , Valerio Pisoni 3,2 , Sara Terrevazzi 3 , Elena Ierman 3 , Donatella Longobardi 3 , Denise Vassena 3 , Tiziana Brandolese 3 , Valeria Enrica Tremolada 1 , Elena De Ponti 1 , Denis Panizza 1,2 , Stefano Arcangeli 2,3 1 Medical Physics, Fondazione IRCCS San Gerardo dei TIntori, Monza, Italy. 2 School of Medicine and Surgery, University of Milan Bicocca, Milan, Italy. 3 Radiation Oncology, Fondazione IRCCS San Gerardo dei TIntori, Monza, Italy Purpose/Objective: Breast cancer represents one of the most common sites treated with radiotherapy. Traditionally, breast irradiation is delivered without dedicated immobilization devices other than arm support, with the patient’s chest fully exposed. In women with larger breast volumes, gravitational displacement can create skin folds and areas of hotspots and dose inhomogeneity. A new immobilization system, the Chabner XRT® Radiation Bra, was evaluated to determine whether its use improves dose distribution compared to the conventional free-breast setup. Material/Methods: Between March and September 2025, six patients with breast cancer were prospectively enrolled. Each underwent two CT simulations: with and without the immobilization bra. Targets and organs at risk (OARs), including ipsilateral lung, heart, and contralateral breast, were contoured on both CT datasets by the same radiation oncologist. The planning target volume (PTV) was generated with a 7 mm CTV expansion, cropped 5 mm from the skin surface; the skin was defined as the outer 5 mm of the body contour. Distances from nipple to pectoralis muscle, and breast medio-lateral and cranio-caudal extensions were also recorded. All treatment plans prescribed 26 Gy in five fractions. Two field-in-field plans using 6 or 10 MV tangential beams were generated in Monaco TPS with EZFluence (RadFormation) by the same medical physicist. Dosimetric differences in target coverage, OAR doses, and anatomical parameters between setups were compared. Differences exceeding 3% or 2 Gy were considered clinically significant.
by 3.0% (range: –0.5 to 18.7%), respectively. Anatomical measurements showed average
differences of 5.2 mm, 5.3 mm, and 15.0 mm in the nipple–pectoralis, mediolateral, and craniocaudal directions, respectively, with the bra setup increasing the nipple–pectoralis distance and reducing mediolateral and craniocaudal breast extensions.
Conclusion: The use of an immobilization bra was associated with modest but clinically meaningful reductions in low- dose exposure to the ipsilateral lung and heart. Defining a quantitative anatomical threshold is needed to better identify which patients derive the greatest benefit from its use. Recruitment to reach the planned sample size (n=20) is ongoing for confirmatory analysis. Keywords: Immobilization, Breast, Plan Comparison Digital Poster 1503 Heart irradiation in breast treatment with VMAT and tangential Field-in-Field techniques Antonella Stravato 1,2 , Antonella Fogliata 3 , Luca Cozzi 3 1 Medical Physics, A.O. San Giovanni-Addolorata, Rome, Italy. 2 Medical University, UniCamillus University, Rome, Italy. 3 Radiotherapy and Radiosurgery,
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