ESTRO 2024 - Abstract Book

S5507

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

Code Red for IGRT traffic-light-protocols as a communication mechanism in the treatment of LA-NSCLC

Dylan Callens 1,2 , Jan Verstraete 1 , Patrick Berkovic 1,2 , Maarten Lambrecht 1,2 , Wouter Crijns 1,2

1 University Hospitals Leuven, Department of Radiation Oncology, Leuven, Belgium. 2 KU Leuven, Laboratory of Experimental Radiotherapy, Leuven, Belgium

Purpose/Objective:

During radiotherapy of locally advanced non-small cell lung cancer (LA-NSCLC), intra-thoracic anatomical changes (ITAC) may have a dosimetric impact, prompting the need for Adaptive Radiotherapy (ART). Detection of these changes, which can be challenging to recognize on daily conventional Cone Beam CT (CBCT) imaging, are often managed through a traffic-light-protocol (TLP). These TLPs facilitate an RTT-driven Image-Guided Radiotherapy (IGRT) workflow, reducing uncertainty and interobserver-variability through clear standardized decision criteria. The primary aim of this study is to evaluate the use of TLP’s in clinic through a retrospective (peer) review. Codes were studied in terms of frequency, type of criteria, and time spend on image interpretation. Secondly, a potential reporting fatigue is examined by comparing the implementation phase (April 2019 – July 2019) with the current clinical use (August 2022- August 2023).

Material/Methods:

A total of 1708 fractions from 63 LA-NSCLC patients, treated between August 2022 and August 2023, were retrospectively evaluated by an RTT IGRT specialist. The retrospective evaluation is executed blinded from the reported code in clinical routine. Additionally, the same evaluation was executed for the implementation phase, defined as three months after introduction in April 2019. For this, a total of 289 fractions were retrospectively evaluated from 11 patients. Of all included patients, 64 patients were treated on a Halcyon unit, and 10 patients on a TrueBeam unit. The retrospective evaluation is executed in the Offline Review platform of Varian. In our clinic, orange/red traffic light codes are digitally reported utilizing an offline workstation equipped with the CarePath task platform of Varian's Oncology Information System. The TLP is depicted in Figure 1 . The protocol involves evaluation of the target, spinal canal and lungs. Within this predefined context RTT's make the decision to proceed the treatment (i.e. code green) , request offline feedback from the responsible physician (orange) , or request online support from the treating physician (red) . As a backup mechanism, a randomly selected CBCT is evaluated weekly by radiation oncologists. All RTTs receive annual TLP-refresher courses. Additionally, there are demo-stations where new RTTs are trained in IGRT.