ESTRO 2023 - Abstract Book

S141

Saturday 13 May

ESTRO 2023

Since the early ´90ies adjuvant chemotherapy – mainly cisplatin with or without 5-FU – hast been used for certain indications in combination with postoperative radiotherapy (PORT) after surgery for oral cavity cancer. The presentation will discuss why cisplatin is valuable in combination with radiotherapy and the present well-established indications: positive margins, extracapsular extension and TNM classificationT3-4 and/or N2-3. The actual evidence for the more relative indications will also be revisited, like perineural or lympho-vascular invasion, depth of tumor invasion and positive resection margins followed by additional resection. Recently, the discussion of what is actually positive margins and ECE has been revitalized and together with the importance of p16/HPV status this will be debated. Furthermore, the evidence for doses and types of drugs is discussed and finally, a list of burning research questions for the future is suggested.

Pitch Session: Will automation of radiotherapy tasks solve more problems than it causes?

SP-0198 Setting the scene B. Heijmen The Netherlands

Abstract not available

SP-0199 Target volume contouring automation: Technical perspective C. Brouwer The Netherlands

Abstract not available

SP-0200 Target volume contouring automation: Clinical perspective E. Rivin del Campo 1 1 Tenon University Hospital, Sorbonne University, Department of Radiation Oncology, Pars, France

Abstract Text Automated target volume delineation is steadily integrating daily clinics. Not only is it used for contouring within the classic radiation therapy (RT) workflow, on the planning CT scan. It actually is key for enabling new adaptive RT (ART) workflows to be carried through within a more acceptable timeframe. Besides reducing the time needed for contouring, this innovation also reduces interobserver contouring variability. Contouring has always been considered the weakest link in the RT planning workflow, due to interobserver variability. Thus, automated contouring may add robustness to the RT planning workflow. However, special attention must be used when applying it. There are certain tumor sites, such as head and neck, or post-operative adjuvant treatments, where automated target volume delineations are less satisfactory. Furthermore, adaptation of the automated contours may be done differently depending on the RT workflow context. During the classic RT workflow, when contouring on a planning CT, the radiation oncologist has the time to review the complete medical history, other imaging, and leisurely look through and modify the automated target volume contours. In the case of the ART workflow, with the patient on the table, time efficiency is needed. This should be taken into consideration in this workflow, to avoid any possible contouring editing errors due to the time-crunch. Additionally, to be able to adapt the automated target volume delineations accordingly, radiation oncologists must have adequate knowledge of contouring of the target volume beforehand. A major question at this time is how to best and effectively train radiation oncologists to contour using automated target volume delineation. Another consideration are the legal implications with respect to the medical responsibility when these automated target volumes are evaluated and edited. Depending on how a medical error incurs within this workflow, the responsibilities may differ. SP-0201 Planning automation L. Marrazzo 1 1 University of Florence, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Firenze, Italy Abstract Text Manual interactive inverse plan optimization for Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) is workload and time intensive, while plan quality may heavily depend on planner’s expertise, time availability for planning, and ambition of the planner and treating physician. In the last few years, automatic planning (AP) has been introduced. Different approaches to AP can be used, the most common methods being knowledge-based planning (KBP), protocol-based automatic iterative optimization (PB-AIO), and multicriteria optimization (MCO), which can be pareto-navigation driven or automated. Some kind of solution is now available in most commercial treatment planning systems. There are clear advantages of AP, the most significant being enormous decrease in planning workload, inter-operator variability reduction, and overall plan quality improvement, the latter depending on the applied AP system and configuration. However, the process of introducing AP in clinical practice is generally complex and laborious, requiring extensive algorithm configuration and validation, since a suboptimal configuration translates into a plan quality systematically lower than feasible. Moreover, a continuous effort is required to keep AP up to date, since implementation of new optimizers, cost functions or configuration options might rise opportunities for enhancing quality of automatically generated plans. AP must also be continuously adapted to new prescription strategies, fractionation schemes, volume definitions, dose constraints and delivery approaches. The need for monitoring the accuracy/consistency of AP output over time and robustness to adapted workflows is generally time consuming and not straightforward.