Vienna, Austria

ESTRO 2023

Session Item

May 13
16:45 - 17:45
Business Suite 1-2
Technical improvements in radiotherapy practice
Rianne de Jong, The Netherlands
Poster Discussion
A pulmonary vein atlas for radiotherapy planning
Gerard Walls, United Kingdom


A pulmonary vein atlas for radiotherapy planning

Gerard Walls1, Conor McCann2, Peter Ball3, Katelyn Atkins4, Ray Mak5, Ahmed Bedair6, Jolyne O'Hare7, Jonathan McAleese7, Claire Harrison7, Karen Tumelty7, Cathryn Crockett7, Sarah-Louise Black7, Catherine Nelson7, John O'Connor1, Alan Hounsell7, Conor McGarry7, Karl Butterworth1, Aidan Cole7, Suneil Jain1, Gerry Hanna1

1Queen's University Belfast, Patrick G Johnston Centre for Cancer Research, Belfast, United Kingdom; 2Belfast Health & Social Care Trust, Department of Cardiology, Belfast, United Kingdom; 3Belfast Health & Social Care Trust, Department of Radiology, Belfast, United Kingdom; 4Cedars-Sinai Medical Center, Department of Radiation Oncology, Los Angeles, USA; 5Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Department of Radiation Oncology, Boston, USA; 6North West Cancer Centre, Department of Clinical Oncology, Derry, United Kingdom; 7Belfast City Hospital, Northern Ireland Cancer Centre, Belfast, United Kingdom

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Purpose or Objective

Cardiac arrhythmia is a recognised potential complication of thoracic radiotherapy (RT) but the cardiac substructures responsible for arrhythmogenesis in this setting have not been identified. Arrhythmogenic tissue is commonly located in the pulmonary veins (PVs) of cardiology patients with atrial fibrillation (AF), however these structures are not currently considered organs-at-risk during RT planning. Pre-clinical and clinical research recently indicates that the PVs can be isolated with SABR, akin to invasive cardiac ablation, yet a standardised approach for delineation has not been published. Herein we developed and evaluated a PV atlas for RT planning.

Material and Methods

The gross and radiological anatomy relevant to AF was derived from the cardiology and radiology literature by a team of radiation oncologists, electrophysiology cardiologists and thoracic radiologists. A region of interest and contouring instructions for 4-dimensional CT RT planning scans were iteratively developed in-house, with input from external collaborators. Given that the myocardial sleeve tissue, which is located within a short central portion of the PV walls, is the source of AF in cardiology, this was identified as the region of interest for RT treatment planning purposes. To evaluate the application of this atlas, radiation oncologists (n=5) and radiation technologists (n=2) contoured the PVs on the 4D planning scans of five patients with locally advanced lung cancer. Interobserver variation in the segmentation was then assessed by comparing the manual contours to reference contours agreed by the lead researchers, using geometric and dosimetric parameters.


Using the atlas designed the mean dose to the PVs in the five datasets for evaluation was 35% of the prescription dose and the mean Dmax was 61%. Geometric and dosimetric similarity of the observer contours with reference contours was good when the atlas was applied, with an overall mean Dice of 0.80 ± 0.02. The right superior PV (mean DSC 0.83 ± 0.02) had better overlap than the left superior PV (mean DSC 0.80 ± 0.03), but the inferior PVs were equivalent (mean DSC of 0.78). The mean magnitude of directional shifts was 1.8mm and shifts in the right-left axis were equally balanced in direction. Shifts in the cranio-caudal and dorso-ventral axes were in the one direction only however. Hausdorff distances were also low generally. The mean difference in mean dose was 0.79Gy (1.46%) and the overall mean Dmax difference was 0.28Gy (0.58%).


A PV atlas with multidisciplinary approval led to reproducible delineation for RT planning, with Dice values comparable to those for other cardiac substructure atlases. Clinical dosimetric studies of consistently contoured PVs could facilitate the derivation of safe dose thresholds below which RT-related arrythmia is unlikely. The atlas outlined may also have applications in the evolving field of SABR for cardiac arrhythmia in providing guidance for consistent identification of the PVs.