ESTRO 2025 - Abstract Book

S3070

Physics - Image acquisition and processing

ESTRO 2025

period. This can be achieved with 2D cine (dynamic MRI), in the main directions of the tumour motion. This type of imaging has therefore become an important tool for motion management in treatment with MRI linacs. A multicentre prospective trial is ongoing, comparing the use of 4D-CT with 2D-cine MRI for evaluating tumour motion in lung SBRT. For 150 patients, the images presented in Figure 1 will be acquired. This work reports on preliminary results from the pilot cohort, regarding the tumour visualisation on the 10mm versus 15mm 2D-cine MRI series.

Material/Methods: The pilot cohort consists of the 10 first patients included in the trial after signing informed consent. Their SBRT treatment was given according to local clinical practice, and the trial-specific images were not used to modify the treatment. Patients were scanned in treatment position in the SBRT body frame with a 1.5 T Philips Ingenia scanner. Two versions of the 2D-cine images (balanced turbo field echo) were acquired, using a plane depth of 10 mm and 15 mm respectively, exploring the trade-off between tumour contrast and the feasibility of fully capturing the tumour motion. Results: Out of the 10 recruited patients, 9 completed the full MRI protocol (1 interrupted due to discomfort). Table 1 shows the characteristics of the cohort. In all cases, the tumour could be identified on both 2D-cine MRI.