S611
Clinical – Head & neck
ESTRO 2026
participating centres to perform gamma camera set up procedures that enabled quantitative imaging of I- 131 by characterisation of image resolution and deadtime. Data were collated via the RTTQA transfer service at to a central processing site for dosimetry calculations. Radiation dosimetry was performed from ROI delineation on sequential images and application of Dose Factors to time integrated activities. Results: To date, 127 patients have been recruited. The study is expected to complete in March 2026. Initial results show a wide range of radiation doses delivered to thyroid remnants (< 1 Gy - > 1000 Gy) and to salivary glands (Median 0.7 Gy, Range 0.2 to 12.1 Gy). Salivary gland toxicity data have shown an increase in CTCAE grade in just under 50% of patients. Excellent biochemical response rate has been seen at 9-12 months in 71% of patients with completed follow-up. Conclusion: This study has demonstrated the feasibility of performing investigator-led dosimetry trials for molecular radiotherapy, employing standardised quantitative imaging and dosimetry and centralised data processing. The wide range of radiation doses delivered indicate the potential for personalised treatments as is routine for external beam radiotherapy. The methodologies and designs developed for these studies are readily applicable to the rapidly expanding field of molecular radiotherapy demonstrating that radiation dosimetry is feasible and of clinical importance. References: Taprogge J et al. Predictive factors of radioiodine ablation success: results from a MEDIRAD prospective clinical study for thyroid cancer. https://doi.org/10.1530/ETJ-25-0097. 2025Taprogge J/Vergara Gil A et al. Normal organ dosimetry for thyroid cancer patients treated with radioiodine as part of the multi - centre multi - national Horizon 2020 MEDIRAD project. https://doi.org/10.1007/s00259-023- 06295-0. 2023Taprogge J et al. Physics aspects of setting up a multicenter clinical trial involving internal dosimetry of radioiodine treatment of differentiated thyroid cancer. DOI: 10.23736/S1824-4785.19.03202-3. 2019 Keywords: Radioiodine Dosimetry
Conclusion: This is the first prospective study to show that DL- based IMPT planning yields acute side-effect profiles comparable to those observed among OPC patients treated with manually planned IMPT. These findings indicate that DL-based IMPT planning can uphold clinical standards while offering substantial gains in planning efficiency. Keywords: deep learning planning, IMPT, acute side effects INSPIRE: An investigator-led prospective study of radiation dosimetry for radioiodine treatment of thyroid cancer Glenn Flux 1 , Jan Taprogge 1 , Hannah Sharman 1 , Kee Howe Wong 2 , Kate Newbold 2 1 Physics, Royal Marsden Hospital, Sutton, United Kingdom. 2 Thyroid Unit, Royal Marsden Hospital, Sutton, United Kingdom Digital Poster 3027 Purpose/Objective: Radioiodine has been used to treat thyroid disease for over 80 years, although there have yet to be multi- centre trials to investigate the radiation dosimetry. The aim of this observational multi-centre study was to determine the range of radiation doses delivered to thyroid remnants and to salivary glands and to evaluate correlations with treatment outcomes. Material/Methods: The INSPIRE trial aims to recruit 150 patients in 10 UK centres and follows a previous EU HORIZON study, MEDIRAD, performed in four centres in Germany, France and the UK. Site visits were carried out to
Digital Poster Highlight 3036
Dose de-intensification radiotherapy after induction chemotherapy for nasopharyngeal carcinoma Jin-Ching Lin 1 , Wen-Yi Wang 2 , Chih-Wen Twu 3 1 Department of Radiation Oncology, Changhua Christian Hospital, Changhua, Taiwan. 2 Department of Nursing, Hung Kuang University, Taichung, Taiwan.
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