ESTRO 2025 - Abstract Book

S3047

Physics - Image acquisition and processing

ESTRO 2025

3406

Proffered Paper Prioritising lung function: using novel dynamic 19F MRI to quantify ventilation for non-small cell lung cancer radiotherapy treatment planning Rachel A Pearson 1,2 , Philip Atherton 1 , Dominic Harrison 2 , Adam Hassani 1 , Charlotte W Holland 2 , Hazel McCallum 2,1 , Fiona E McDonald 1 , Mary A Neal 2 , Julian Phillips 1 , Rebecca Pickles 1 , Eleanor Smith 1 , Alexander Stamp 1 , Helen Turnbull 1 , Samantha Warren 1 , Nicholas Willis 1 , Peter Thelwall 2 1 Northern Centre for Cancer Care, Newcastle-upon-Tyne NHS Trust, Newcastle-upon-Tyne, United Kingdom. 2 Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom Purpose/Objective: Radiotherapy planning requires careful consideration to minimise dose exposure of susceptible normal tissues, whilst ensuring adequate dose to the tumour target. For treatment planning in non-small cell lung cancer (NSCLC) whole anatomical lung dose is taken into consideration, but radiation induced lung injury occurs in 5-50% of patients and can cause serious sequelae [1]. There is potential to reduce the effect of this for patients by directing radiation dose away from lung tissue that is functioning well. Whilst several studies have tried to address the issue of identifying regional lung function for radiotherapy planning using both CT/PET and 129 Xe-MRI [2, 3] there is currently no consensus as to how this should be done. This study demonstrates the feasibility of using novel 19 F MRI to create 3D maps of Regional Lung Clearance Index (RLCI; the number of breaths required to turnover 97.5% of gas within each image voxel) in patients undergoing radiotherapy treatment for NSCLC, to map areas of “good”, “intermediate” and “poor” lung ventilation. 2 gas mixture was performed in patients with NSCLC [4]. Gas wash-in dynamics were assessed, and RLCI was calculated across the entire lung volume to quantify regional lung ventilation. RLCI thresholds of 10 and 20 we used to stratify the lung into areas of “good”, “intermediate” and “poor” lung function, as compared to healthy volunteer data (Figure 1) Regions of stratified RLCI were then mapped to radiotherapy planning CT scans in Raystation, and radiation dose delivered to each strata of functional lung was calculated. Results: 19 F MRI maps of Regional Lung Clearance have been successfully acquired for NSCLC patients with a range of dose/fr regimes (including SABR and concurrent chemo-radiotherapy) and PTV size 69.4 - 458 cm 3 . Compared to a healthy volunteer, lung cancer patient RLCI histograms presented an increased right-skew (Fig. 1), indicating an increased proportion of pulmonary regions with reduced ventilation. Material/Methods: Multiple breath-hold dynamic 19 F-MRI using a 79% PFP/21% O