ESTRO 2024 - Abstract Book

S4255

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2024

References:

1. Glynne-Jones, R., et al., Rectal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow up. Ann Oncol, 2017. 28(suppl_4): p. iv22-iv40. 2. de Jong, R., et al., Feasibility of Conebeam CT-based online adaptive radiotherapy for neoadjuvant treatment of rectal cancer. Radiation Oncology, 2021. 16(1): p. 136. 3. van Herk, M., et al., The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy. Int J Radiat Oncol Biol Phys, 2000. 47(4): p. 1121-35. 4. Nijkamp, J., et al., Target volume shape variation during hypo-fractionated preoperative irradiation of rectal cancer patients. Radiother Oncol, 2009. 92(2): p. 202-9. 5. Wanet, M., et al., Validation of the mid-position strategy for lung tumors in helical TomoTherapy. Radiother Oncol, 2014. 110(3): p. 529-37.

1370

Poster Discussion

Systematic intrafraction drift motion of lymph nodes during lung cancer DIBH radiotherapy sessions

Per R Poulsen 1,2 , Hoffmann Lone 3,2 , Ghulam Murtaza 4,1 , Mai L Ehmsen 1 , Jenny Bertholet 5 , Marianne M Knap 3 , Esben S Worm 3 , Ditte S Møller 3,2 1 Aarhus University Hospital, Danish Centre for Particle Therapy, Aarhus, Denmark. 2 Aarhus University, Department of Clinical Medicine, Aarhus, Denmark. 3 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark. 4 University of Management and Technology, School of Health Sciences, Lahore, Pakistan. 5 Inselspital, Bern University Hospital, and University of Bern, Division of Medical Radiation Physics and Department of Radiation Oncology, Bern, Switzerland

Purpose/Objective:

Treatment in deep-inspiration breath-hold (DIBH) may reduce intrafraction motion and thus the motion margins needed in radiotherapy of lung cancer. However, DIBH is typically guided by an external surrogate signal, which may not correlate well with the actual internal target motion. Therefore, recent ESTRO-ACROP guidelines on the implementation of breath-hold techniques stressed the need for internal target position imaging during thoracic DIBH treatments [1]. Based on a rich dataset including more than 1600 breath-holds (BH) for 16 lung cancer patients, this study investigates the 3D intrafraction drift motion of mediastinal lymph node (LN) targets at three different time scales: during individual breath-holds, between consecutive breath-holds and between pre-treatment and post treatment CBCT scans.

Material/Methods:

Sixteen patients with locally-advanced lung cancer were treated with 66 Gy in 33 fractions (n=11) or with 50 Gy in 24 fractions (n=3) for non-small cell lung cancer, or with 45 Gy in 30 fractions (n=2) for small cell lung cancer. The