ESTRO meets Asia 2024 - Abstract Book

S6

Invited Speaker

ESTRO meets Asia 2024

carried out using Monte Carlo (MC) simulations. Further, optimum audit setup and the influence of the underlying table material thickness also were simulated. All MC simulations were validated experimentally where applicable. To evaluate the influence of the radiation energy spectra on the RPLD, various HDR source models were simulated. A 16 × 8 × 3 cm phantom made of Polymethyl Methacrylate (PMMA) with a radiophotoluminescent dosimeter (RPLD) at the centre and two catheters on either side was developed. A treatment plan consisting of 13 dwell positions in each catheter with uniform dwell times with 5 mm step size, calculated using the TG-43 algorithm for a prescription dose of 2 Gy to the centre of the RPLD was prepared. The source position shifts were monitored with the dosimetry film inserted in the phantom. The methodology was tested in a pilot study with participants from eleven countries. A total of 59 dosimeter sets were irradiated with 45 192 Ir and with 14 60 Co HDR sources, using 49 brachytherapy afterloaders of various models. Results: The correction factors for non-water equivalence of detector, the use of PMMA and lack of full scatter were 1.062 ± 0.013, 0.993 ± 0.009 and 1.059 ± 0.008 for 192 Ir and 1.129 ± 0.005, 1.005 ± 0.005 and 1.009 ± 0.005 and for 60 Co respectively. Placing the phantom on a table with water-equivalent backscatter thickness of 5 cm was found to be adequate and increasing thickness of backscatter did not have an influence on the RPLD dose. The mean (SD) dose ratio of the participant to the IAEA reference dose in the pilot study was 1.008 (0.015), and 1.007 (0.011) for the 192 Ir and 60 Co respectively. An absolute average shift of source position in respect to the plan was of 1.2 mm ± 2.5 mm. Conclusions: The IAEA /WHO postal dosimetry audit methodology for HDR brachytherapy has been developed and was successfully tested in an international multicentre pilot study. This experience is crucial for the development of more advanced end-to-end audit, which is currently under development.

476

Advances in SGRT technology

Yao Guorong

Radiation Oncology, the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China

Abstract

Surface Guided Radiation Therapy (SGRT) is a cutting-edge technique in radiotherapy that employs optical surface monitoring for patient positioning and real-time monitoring without radiation. With its extensive clinical applications, SGRT has been instrumental in treating various cancers, including breast, head and neck, brain metastases, thoracoabdominal, and limb tumors. It excels in reducing positioning errors, enhancing respiratory motion management, and is particularly beneficial for special patient populations like children and the elderly. The technology's future is poised for significant advancements, with a focus on personalized treatment, AI integration, and improved efficiency. The combination with deep inspiration breath hold (DIBH) technology further minimizes radiation exposure to healthy tissues. SGRT's non-radiative nature makes it an ideal choice for pediatric and geriatric patients, enhancing patient safety and comfort. Research trends indicate a promising direction towards using deformable surfaces as motion surrogates and leveraging AI neural networks with various sensors to track anatomical changes more accurately. As SGRT continues to evolve, it is expected to integrate with other technologies and establish stricter quality assurance procedures, ensuring a comprehensive and efficient treatment approach. The potential of SGRT in the radiotherapy field is vast, promising to revolutionize patient care with its precision and adaptability.