ESTRO 2024 - Abstract Book

S4266

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

ESTRO 2024

1584

Digital Poster

REAL-TIME INTRAFRACTION MOVEMENT OF THE PROSTATE USING AN ELECTROMAGNETIC TRACKING DEVICE

Jose Maria Penedo 1 , Maria Angeles García 1 , Magnolia Rincón 1 , Jesús Olivera 2 , Ignacio Navarro 2 , Daniel Martinez 1 , Sylvia Gomez 1 , Marta Perez 2 , Ignacio Azinovic 2 1 Fundación Jiménez Diaz Hospital, Physics, Madrid, Spain. 2 Fundación Jiménez Diaz Hospital, Radiation Oncology, Madrid, Spain

Purpose/Objective:

The Ray Pilot System (RayPilot® System) is an electromagnetic tracking system that measures the position of a transmitter located in a fixed position within a specific urethral catheter. This transmitter moves in solidarity with the urethra and therefore takes into account the intrafractional movement of the prostate in the three axes.

The purpose of this study is to report the results obtained for prostate SBRT using this new monitoring system.

Material/Methods:

75 sessions were analyzed for a total of 15 patients. The prescribed dose was 36.25 Gy in 5 sessions. The plans were optimized to achieve D98% ≥ 95% in the PTV (CTV + 2mm) and meet restrictions for the OARs. The treatment was planned in the Monaco system v.5.11.03. An arc with 6 MV FFF energy was used with the VMAT technique. Simulation CT was done on a Philips Brilliance Big Bore CT with a slice thickness of 1 mm. A urethral catheter of the same geometry, as the one used during the treatment (HypoCath), was placed in the patient. The bladder was filled with 100 ml of physiological saline. This bladder volume was reproduced for each treatment session.

The treatment was carried out in an Elekta Synergy® accelerator, which incorporates a Cone Beam CT (CBCT) volumetric imaging system for patient positioning, using XVI v.5.0.6 software.

On the first day of treatment, the urethral catheter with the radiofrequency transmitter was placed in the patient and was maintained throughout the duration of the treatment.

The movement of the transmitter, placed within prostate, provided real-time localization of the prostate during treatment delivery.

Irradiation was stopped manually when the transmitter displacement exceeded 2 mm. A new CBCT was performed and the necessary movements were made with the Precise table to reposition the patient.

Results: