ESTRO 2025 - Abstract Book

S11

Invited Speaker

ESTRO 2025

The virtual dosimetry equipment in VERT can be set up with positioning/ alignment errors. These can be used to gain appreciation of their impact or purposefully introduced (by the teachers) in assessments to test if the trainee can spot and correct them. Similarly, systematic and random beam output or calibration errors can be simulated. Measurements are subject to random fluctuations, with configurable magnitude, requiring repeat measurement to be taken to assess the mean value and associated uncertainty in measurement. Along with the more general features available in VERT, the TRS398 and TRS 483 modules have been used during the ESTRO Practical Dosimetry Audit course (2023) at the UK National Physical Laboratory (NPL), their own Practical Course in Reference Dosimetry (2023/ 2024) and integrated into the Radiotherapy Physics module of the University College London (UCL) Physics and Engineering in Medicine MSc (2025). During the NPL courses VERT was used alongside practical measurement sessions on their Linacs, to virtually explore simulated error scenarios, impact of uncertainties, equipment management and the faculty’s vast experience of commonly experienced problems. The latter included ‘detector choice uncertainty’ for very small field factors, which otherwise could not be accommodated in practical sessions due to time constraints. The impact of the use of wrong field sizes during TPR20/10 measurement, SSD errors, wrong energy selection, lack of monitoring the ambient conditions by changing room temperature and pressure were explored extensively.

Participant feedback was enthusiastic, and faculty reflected that simulation sessions had broadened the teaching, adding value to training beyond that given by the practical training.

VERT was used in the classroom on the UCL MSc course to provide virtual clinical demonstrations; course work was set for the students as follow up to the lectures to assess their understanding, using the remote access VERT LMS.

Conclusion

VERT allows trainees to understand the need for accuracy by providing a platform to explore the impact of poor measurement processes and has proven to add value to existing professional training courses for Radiotherapy Physicist training. The key benefit of simulation training is the ability to safely explore ‘never-events’ and errors. It standardises the training experience and is likely to help expand training schemes where provision of resources, expertise and travel prove challenging.

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Speaker Abstracts Same-day radiotherapy without prior CT simulation Joshua Schiff Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, USA

Abstract:

The standard clinical workflow for radiation oncology treatment consists of a consultation appointment followed by a computed tomography (CT) simulation appointment, treatment planning, and treatment delivery, often occuring over the course of several days to weeks. With workflow and technologic advancement in radiation oncology over the last several years, much work has been done to optimize this workflow to increase the efficiency with which a patient is able to get on beam. One such advancement has been direct to unit, or simulation-free, radiotherapy in which traditional CT simulation is forgone and a patient's diagnostic imaging is used for treatment planning. In these workflows, a diagnostic scan based pre-plan is created and used for treatment planning, often coupled with the use of advanced on-board imaging acquired on the day of direct to unit radiotherapy to optimize patient alignment. Direct to unit radiotherapy is most commonly used for conventional palliative radiotherapy delivery in