ESTRO 2021 Abstract Book

S457

ESTRO 2021

model of professional education that aimed to produce reflective practitioners who are professional decision makers. It delivers RTTs who can adapt to a changing practice environment with the range and level of knowledge, skills and expertise required for professional registration. The RTT curriculum combines the behavioural and generic attributes, knowledge and critical thinking which are essential to effective practice and are transferrable. This integrated, holistic, contextualised approach to education allows for complex combinations of knowledge, skills, values and attitudes to make the RTT both adaptable, flexible and fit for practice and provides an appropriate base for future development as advanced and consultant level practitioners. Our educators are creating RTTs who are not just fit for practice today but who are adaptable and reflective and can embrace new technology as it develops. These are the qualities that provide a long-term endorsement of the RTT’s capabilities and allows them to be flexible and develop in a rapidly changing practice environment. Therefore, I believe that RTT education will continue to be fit for purpose for the future of our profession.

SP-0587 M. Kearney Ireland

Abstract not available

SP-0588 H. Nisbet United Kingdom

Abstract not available

Symposium: Project from A to Z in a hot or new topic Where do you start? And how to publish?

SP-0590 Starting in FLASH RT V. Favaudon 1 1 Institut Curie, Inserm U 1021, Orsay, France

Abstract Text Background and aims

Studies on mammalian cell response to ultrahigh dose rate irradiation (UHDR, 10 6 -10 7 Gy/s) started in 1995 at my initiative within Inserm U 350 at Institut Curie. We used a 5 MeV linac operated in a chopped mode for time-resolved investigation of split-dose radiation recovery in tumor cell lines in vitro with interval between pulses ranging from 5 ms to 5 min. The priming pulse was found to elicit a tetraphasic change of the cell radiosensitivity. The phenomenon was named "W-effect" (Int J Radiat Biol 76 (2000) 1233-43 &1621-9). Whether or not it could be used to improve the therapeutic index of RT, was pending. Methods In 2006 colleagues with skilled experience in tumor xenografts (M.-F. Poupon, Institut Curie) and animal anatomopathology (J.-J. Fontaine, National Veterinary School) went to collaborate with us to probe xenograft response and lung fibrosis in normal lung in mice exposed to single- vs. split-dose UHDR. We were successful in receiving a grant from the Institut National du Cancer and started the investigations by the last days of 2006. M.-C. Vozenin (Institut Gustave Roussy & CEA-DSV) joined us shortly after. Results The outcome took us by surprise. Actually, the response of tumor xenografts in Nude mice proved to be independent of the modality of irradiation whilst C57BL/6J mice exposed to bilateral thorax irradiation in single dose only did not develop lung fibrosis. We subsequently compared responses to UHDR vs. continuous irradiation at dose-rates used in conventional RT (CONV ≈ 0.03 Gy/s). In comparison to CONV, UHDR RT spared normal lung from radio-induced fibrosis with at least equivalent levels of tumor control, which has been termed the FLASH effect (Sci Transl Med. 6 (2014) 245ra93). This selective advantage of FLASH has received confirmation from several teams worldwide with regard to loss of neural stem cells and memory after whole-brain irradiation in adult and juvenile mice, cutaneo-muscular necrosis, and intestinal crypt regeneration and gut function in mice. Consistently protection by FLASH over CONV exposures has been shown to interrelate with a lower level of radio-induced senescence and inflammation in lung and brain. Current developments aim at preclinical assays by intraoperative radiation therapy. Conclusion The first skill on managing a daring project is to be resilient for up to the last mile. Actually, with highs and lows, studies extended over 7 years before final publication. The second skill lies in making highly respected colleagues in fields you are not an expert want to collaborate to your project. And thirdly, to make have enough funds to go through with your ideas. When facing unexpected and provocative results, keep cool, carefully explore reference books and old literature in the field, get enough money (financial support to our laboratory over the 2006-2014 period came from four institutions) to repeat the experiment many times, try to view your own work in a larger context and share the results.

SP-0591 Cardiac radioablation M. Fast 1