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The roles and responsibilities of radiation therapists (RTTs) are many and varied. Professional expectations are influenced by the technology available, as well as the level of autonomy RTTs have in their daily practice. This professional range requires RTTs to possess a unique set of ever evolving skills, posing challenges from an educational perspective. Teaching these “advanced skills” has been the ambition the ESTRO Advanced Skills in Modern Radiotherapy course. In the 10th year of this course, the Faculty look back and reflect on how our programme has evolved and what it has achieved., The roles and responsibilities of radiation therapists (RTTs) are many and varied. Professional expectations are influenced by the technology available, as well as the level of autonomy RTTs have in their daily practice. This professional range requires RTTs to possess a unique set of ever evolving skills, posing challenges from an educational perspective. Teaching these “advanced skills” has been the ambition the ESTRO Advanced Skills in Modern Radiotherapy course. In the 10th year of this course, the Faculty look back and reflect on how our programme has evolved and what it has achieved.

Item does not contain fulltext, Objective.In online adaptive radiotherapy a new plan is generated every fraction based on the organ and clinical target volume (CTV) delineations of that fraction. This allows for a planning target volume margin that does not need to be constant over the whole course of treatment, as is the case in conventional radiotherapy. This work aims to introduce an approach to update the margins each fraction based on the per-patient treatment history and explore the potential benefits of such adaptive margins.Approach.We introduce a novel methodology to implement adaptive margins, isotropic and anisotropic, during a treatment course based on the accumulated dose to the CTV. We then simulate treatment histories for treatments delivered in up to 20 fractions using various choices for the standard deviations of the systematic and random errors and homogeneous and inhomogeneous dose distributions. The treatment-averaged adaptive margin was compared to standard constant margins. The change in the minimum dose delivered to the CTV was compared on a patient and a population level. All simulations were performed within the van Herk approach and its known limitations.Main results.The population mean treatment-averaged margins are down to 70% and 55% of the corresponding necessary constant margins for the isotropic and anisotropic approach. The reduction increases with longer fractionation schemes and an inhomogeneous target dose distribution. Most of the benefit can be attributed to the elimination of the effective systematic error over the course of treatment. Interpatient differences in treatment-averaged margins were largest for the isotropic margins. For the 10% of patients that would receive a lower than prescribed dose to the CTV this minimum dose to the CTV is increased using the adaptive margin approaches.Significance.Adaptive margins can allow to reduce margins in most patients without compromising patients with greater than average target motion.

Contains fulltext : 203208.pdf (publisher's version ) (Closed access), BACKGROUND AND PURPOSE: In recent decades, outcomes of patients with head and neck cancer (HNC) have improved as a result of implementing several strategies, such as chemoradiation. However, these improvements were achieved at the cost of increased toxicity. One way to reduce radiation-related toxicity is by reducing the margins. MATERIALS AND METHODS: Between 2013 and 2016, 206 consecutive patients were treated with CTV-PTV margin of 5mm and subsequently 208 patients with 3mm margin. This study evaluates the impact of reducing clinical target volume (CTV) to planning target volume (PTV) margin on outcome and toxicity. RESULTS: All patients were treated with volumetric modulated arc therapy (VMAT) with daily-image guidance using cone-beam CT (CBCT). Overall acute grade 3 toxicity was significantly lower in 3mm-group, compared to 5mm-group (53.8% vs. 65%, respectively, p=0.032). The same was true for acute grade 3 mucositis (30.8% vs. 42.2%, p=0.008) and for acute grade 3 dysphagia (feeding tube-dependence) (22.1% vs. 33.5%, p=0.026). The incidence of ongoing feeding tube-dependence after 3months of radiotherapy was 11.1% and 20.4%, respectively (p=0.012). The 2-year incidence of late grade >/=2 xerostomia was 15.8% and 19.4% (p=0.8). The 2-year loco-regional control rates of patients treated in 3mm and 5mm-groups were 79.9% and 79.2% (p=1.0). The figures for disease-free survival were 71.5% and 72.7 (p=0.6) and for overall survival were 75.2% and 75.1% (p=0.9). CONCLUSION: Reducing the CTV-PTV margin from 5 to 3mm combined with daily CBCT-guided VMAT reduced the severity, frequency, and duration of radiation-related toxicity without jeopardizing outcome.