9th international symposium on physical, molecular, cellular, and medical aspects of Auger processes: preface.

The 9th International Symposium on Physical, Molecular, Cellular, and Medical Aspects of Auger Processes took place from 22nd to 24th August 2019. This is a quadrennial event that has traditionally been held as a ‘satellite’ meeting of the International Congress for Radiation Research. Removal of an inner orbital electron through the photoelectric effect, electron capture, or internal conversion leads to a vacancy which is then filled by a cascade of electron transitions from the outer shells. These transitions are accompanied by the emission of low energy ‘Auger’ electrons or characteristic X-rays. Auger electrons have low energy (<25 keV), have a short track length and are densely ionizing. As a result, the absorbed radiation dose they deposit in biological material is extremely high but restricted to a nanoscale volume (a few nm) around the decay site. These qualities mean that Auger electron emitting radionuclides are suited to the ultra-precise delivery of radiation to individual cells, organelles or even to specific molecular targets, and so hold promise as oncologic therapeutic agents. The 9th Auger Symposium opened with a plenary presentation by Roger Howell, Rutgers University, who gave a comprehensive exposition of the advances in the use of Auger electrons in science and medicine during the period 2015–2019. The rest of the programme was organized into five scientific sessions focused on the availability and characteristics of ‘new’ Auger electron emitting radionuclides, physics, radiobiology, dosimetry and novel applications. Each session was headed by presentations by leaders in the field followed by selected papers from among submitted abstracts. Some of the research presented at the meeting has now been published as a collection of papers, together with a review article by Roger Howell summarizing his Keynote talk, in this ‘Special Auger Issue’ of the International Journal of Radiation Biology. The current series of Auger Symposia was inaugurated in 1987, when a group of radiation biologists and nuclear physicists met at the modest venue of the Oxfordshire village of Charney Bassett. It felt apt then that the 9th Symposium, which attracted 60 scientists from 13 countries, returned to Oxfordshire, although this time convening in the stunning Sultan Nazrin Shah Center located in the grounds of Worcester College, Oxford University. The scientific sessions were punctuated by opportunities for attendees to network and to enjoy some late summer sunshine and the tranquility of the College gardens and orchards. We would like to thank the other members of the organizing committee (Ana Denis-Bacelar, Bart Cornelissen, Samantha Terry and Akinari Yokoya) for their contributions, Anne-Marie Honeyman-Tafa for administrative assistance and Theragostics and the Gray Laboratory Cancer Research Trust for their sponsorship of the meeting. Auger electrons were independently identified by the physicists Lise Meitner and Pierre Auger; with Pierre Auger’s first paper on the topic published in 1923. This means that the 10th Auger Symposium, due to be held in 2023, will mark the centenary of the discovery. Aptly, since Pierre Auger was French, the 10th Symposium will be held in Montpellier and will be co-chaired by Jean-Pierre Pouget, Institut de Recherche en Cancerologie de Montpellier, and Raymond Reilly, University of Toronto. The community will gather again to share their latest research findings and to explore the intriguing physical and biological phenomena that constitute the ‘Auger effect’.