ESTRO 2024 - Abstract Book

S4377

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

ESTRO 2024

direction and 2.01 mm (±0.95) in longitudinal direction. In figure 1, the data of the CTV motion is shown for the longitudinal, lateral and vertical direction. For 90% of the fractions, the motion ranges between [-1.44; 3.30] mm for the longitudinal direction, between [-1.56; 1.48] mm for the lateral direction and between [-2.70; 2.14] mm in vertical direction. Considering the volume of the CTV receiving 90% of 5x8Gy, the data show a small decrease in average volume of CTV receiving the dose from 98.3% (± 1.2) to 97.3% (±1.7).

Figure 1: Boxplots of the motion in longitudinal, lateral and vertical direction

Conclusion:

We can conclude that in the case of hypofractionated online adaptive prostate treatments, sagittal gating is sufficient and 2D shifts are necessary to not compromise the target coverage. No outstanding lateral shifts were discovered that could affect dose coverage.

Keywords: MR-Guided Radiotherapy, Gating

2799

Digital Poster

Online adaptive radiotherapy without planning CT scan: a prospective clinical trial in rectal cancer

Claudia S.E.W. Schuurhuizen, Judith H. Sluijter, Pim J.J. Damen, Maarten L.P. Dirkx, Joost J.M.E. Nuyttens

Erasmus MC, Radiation Oncology, Rotterdam, Netherlands

Purpose/Objective:

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