ESTRO 2024 - Abstract Book

S4316

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

ESTRO 2024

motion, the IFCBCT image set also showed duplicated seeds, and auto seed registration resulted in a maximum difference of 1.5mm compared to the final position of the phantom. After aligning the seeds from the plan data with the second set of duplicated data, the maximum difference increased to 2.4mm compared to the final position of the phantom.

The target position trajectories determined by SeedTracker showed the motion introduced to the phantom in real time and triggered a treatment interruption warning when the position exceeded the 3mm tolerance.

For hypofractionation and SBRT treatments, IFCBCT imaging resulted in an effective dose of 54.3mSv and 13.6mSv, respectively. With the continuous imaging option available in XVI, SeedTracker-based imaging resulted in an effective dose of 20.3mSv and 9.0mSv for hypofractionation and SBRT, respectively. This represents a reduction of 62.5% and 32.4% compared to IFCBCT-based imaging. Further dose reduction was achieved by decreasing the imaging frequency for the position tolerances of 3mm/1s and 3mm/5s, resulting in a dose reduction of 86.2% and 97.2% for both treatment regimens compared to the IFCBCT approach.

Conclusion:

SeedTracker real-time monitoring successfully identified target position deviations in real-time, a capability not achievable with the IFCBCT approach. Furthermore, the SeedTracker imaging approach significantly reduced the imaging dose in comparison to IFCBCT.

Keywords: Dose optimization, real-time monitoring

References:

1Arumugam S, Sidhom M, Xing A, Holloway L. An online x ‐ ray based position validation system for prostate hypofractionated radiotherapy. Med Phys 2016;43:961–74.

2Arumugam S, Sidhom M, Truant D, Xing A, Udovitch M, Holloway L. Variable angle stereo imaging for rapid patient position correction in an in-house real-time position monitoring system. Phys Medica 2017;33:170–8.

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Digital Poster

Motion management strategy and interobserver variation in abdominal OAR delineation using MRI

Mairead Daly 1 , Lisa McDaid 2 , Carmel Anandadas 3 , Andrew Brocklehurst 3 , Ananya Choudhury 3,1 , Alan McWilliam 4,5 , Ganesh Radhakrishna 3 , Cynthia L Eccles 2,1 1 The University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom. 2 The Christie Hospitals NHS Foundation Trust, Radiotherapy, Manchester, United Kingdom. 3 The Christie Hospitals NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom. 4 The University of Manchester, Radiotherapy Related Research, Manchester,