S2387
Physics - Quality assurance and auditing
ESTRO 2026
isocentre techniques. SRS techniques require extreme spatial accuracy, often in a single fraction. End-to-end dosimetry audits are recommended for all radiotherapy practice to ensure accuracy of treatment delivery and patient safety.This study reports on the design and implementation of a multi-institutional end-to-end SRS dosimetry audit for brain metastases. Targets were either defined virtually or defined via MR visible phantom inserts which needed to be contoured by clinical staff. Material/Methods: Audits were conducted at radiotherapy facilities across Australia and New Zealand using an anthropomorphic phantom (Integrated Medical Technologies, Troy, NY, USA) constructed from five distinct well-defined tissue equivalent CIRS materials: cortical bone (1.93 g/cc), trabecular bone (1.20 g/cc), spinal cord (1.07 g/cc), brain (1.07 g/cc), soft tissue (1.06 g/cc). The phantom mimicked realistic patient anatomy for the skull, facial bones, trachea, sinus, oral cavities and teeth. The phantom included 4 distinct radiochromic film locations and 4 microdiamond (PTW60019) measurement points.
Conclusion: HyperPlan® reliably predicts the spatial energy- absorption and heating behaviour of the Sigma-30, Sigma-60, and Sigma-Eye phased-array applicators. The integration of literature-based and newly acquired experimental data establishes a solid validation framework across the BSD system portfolio. These results confirm HyperPlan® as a robust and accurate platform for clinical hyperthermia treatment planning, applicator quality assurance, and regulatory
certification. References:
[1] Sullivan, “Mathematical methods for treatment planning in deep regional hyperthermia,” IEEE Trans Microw Theory Tech, vol. 39, no. 5, pp. 864–872, 1991, doi: 10.1109/22.79115.[2] Nadobny et al., “Improved patient-specific hyperthermia planning based on parametrized electromagnetic and thermal models for the SIGMA-30 applicator,” International Journal of Hyperthermia, vol. 38, no. 1, pp. 663–678, 2021, doi: 10.1080/02656736.2021.1909757.[3] Bruggmoser et al., “Guideline for the clinical application, documentation and analysis of clinical studies for regional deep hyperthermia: quality management in regional deep hyperthermia,” Strahlenther Onkol, vol. 188 Suppl 2, no. SUPPL. 2, pp. 198–211, Sep. 2012, doi: 10.1007/S00066-012-0176-2. Keywords: Hyperthermia, treatment-planning, SAR- measurements End-to-end dosimetry audit of intracranial stereotactic radiosurgery for multiple brain metastases Andrew Alves, Rhonda Brown, Maddison Shaw Australian Clinical Dosimetry Service, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia Purpose/Objective: Stereotactic radiosurgery (SRS) is an established technique for high precision treatment of small cranial lesions. Uptake of SRS has been shown in patterns of care studies worldwide, with demonstrated safety in concurrent treatment of multiple metastases with a single isocentre, significantly decreasing the treatment time compared to the more traditional multiple Mini-Oral 3832
Results:
SRS onsite audits were performed at 28 facilities. Treatment platforms and image guidance techniques are shown in the table. Single met (n=50), MR-defined multi-met (n=43) and complex multi-met (n=39) audit cases were analyzed. Films were analyzed with a 5%/1mm gamma criteria. Outcomes were based on gamma pass rate: optimal (>95%), action level (>90%), or out-of-tolerance (<90%). All single met cases achieved an optimal outcome. The MR multi-met case included 3 film locations (generating 129 films) with 71.3% optimal, 19.4% action, and 9.3% out-of- tolerance. The complex multi-met case included 4 film locations (generating 155 films) with 83.2% optimal, 10.3% action, and 6.5% out-of-tolerance. Conclusion: There was a preference for some film locations in the multi-met cases to generate a higher proportion of out-of-tolerance outcomes compared to other
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