ESTRO 2024 - Abstract Book

S4388

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

ESTRO 2024

2.5Gy and 2.8Gy for 5 and 2 fractions respectively. This was seen for patient 1 and 3, also representing the fractions with largest target motion.

Comparing motion management strategies, MLC-tracking in 3D resulted in the highest target coverage for all treatment fractions and was closest to the zero-motion baseline for the majority of fractions. For the two fractions with largest target motion, only MLC-tracking in 3D managed to keep the target coverage above 40Gy and 24Gy, followed by gating and 1D tracking.

Conclusion:

Intra-fraction target motion may have significant impact on the dose coverage to the CTV if not corrected for. Large intra-fraction target motion is effectively accounted for using MLC-tracking, enabling high target coverage for all types of motion. Gating may also enable effective motion management, however, there is a risk of compromising the target coverage when the motion is below or close to the gating threshold. For the majority of investigated fractions, intra fraction target motion had minor impact on the delivered dose. However, for individual fractions a large impact was seen. These results emphasise the need for real-time image guidance and motivate the development and clinical implementation of advanced motion management strategies in MR-guided radiotherapy.

Keywords: MLC-tracking, gating, MR-guided

References:

AHMAD, S. B., SARFEHNIA, A., PAUDEL, M. R., KIM, A., HISSOINY, S., SAHGAL, A. & KELLER, B. 2016. Evaluation of a commercial MRI Linac based Monte Carlo dose calculation algorithm with GEANT4. Med Phys, 43, 894-907.

CLINICALTRIALS.GOV. Hypofractionated Expedited Radiotherapy for Men With localisEd proState Cancer (HERMES) [Online]. clinicaltrials.gov. [Accessed 20/07/2021 2021].

HISSOINY, S., RAAIJMAKERS, A. J., OZELL, B., DESPRES, P. & RAAYMAKERS, B. W. 2011. Fast dose calculation in magnetic fields with GPUMCD. Phys Med Biol, 56, 5119-29.

WESTLEY, R., HALL, E. & TREE, A. 2022. HERMES: Delivery of a Speedy Prostate Cancer Treatment. Clin Oncol (R Coll Radiol), 34, 426-429.

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Digital Poster

Comprehensive Analysis of Daily Adaptation on MR-Linac: Unraveling the Imperative for Adaptation

Volkan Demircan, Evren O Goksel, Evrim Tezcanli

Acibadem Altunizade Hospital, Radiation Oncology, Istanbul, Turkey