Note: This is Dept. Grand Round that is not broadcast via the registration link. 

FLASH treatments, i.e. the delivery of radiotherapy with very high dose-rates (>=40Gy/s), is an exciting new development in radiotherapy. At such dose rates, substantial normal tissue sparing effects have been demonstrated in pre-clinical models, whilst tumour response has generally been shown to be preserved. Indeed, the first patient treatment with FLASH has already been delivered with electrons, and larger scale clinical trials are being planned, even if the underlying biology still needs to be fully understood. Given the high dose rates provided by typical proton therapy machines however, it is perhaps inevitable that there is a growing interest in protons for FLASH, and the proton community has not disappointed. In this presentation, after reviewing the current status of proton based FLASH, we will present the work that has taken place at PSI to re-purpose Gantry 1 (taken out of clinical operation in 2018) for FLASH irradiations and describe the first biological experiments that have been performed there. In addition, we will describe the treatment planning simulations we have performed to investigate spatially varying dose-rate distributions, as well as the development and implementation of a simple, phenomenological model of the FLASH effect that can be easily incorporated into the treatment planning process. Based on this, we will demonstrate that achieving clinically relevant FLASH treatments may be as dependent on the delivered dose as it is on dose-rate.

Short bio: Tony Lomax obtained his bachelor degree at Brighton Polytechnic, followed by an MSc and PhD in Medical Physics from the University of Aberdeen. He subsequently worked for 2 years as a medical physicist in the National Health Service, before moving to Switzerland in 1992 to work in the Center for Proton Therapy at the Paul Scherrer Institute. In 2001 he became head of the Medical Physics group for the proton therapy project there. His main research interests lie in the development of intensity modulated proton therapy, problems of robustness and uncertainty in treatment delivery and effects of organ motion for dynamic radiotherapy.  Since April 2005, he has been a faculty member of the Physics Department at ETH (Swiss Federal Institute of Technology), Zurich and is currently joint director of the Master of Advanced Studies in Medical Physics and the medical physics track of the Bio-Medical Engineering Master’s program at the same institute. In 2007 he was made Titular Professor in the Physics Department at ETH.  From 2010-2014, he was on the editorial board of ‘Physics in Medicine and Biology’ and remains on the international advisory board. He is a regular member of the scientific committees for ASTRO, ESTRO, AAPM and the ICCR and since 2015 is the physics co-chair of the PTCOG Scientific Program Sub-committee. He is the author or co-author of over 200 peer reviewed papers, 13 book chapters and more than 500 invited and proffered conference presentations.