ESTRO 2024 - Abstract Book

S4249

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

ESTRO 2024

analyses, the Pearson R coefficient ranges from 0.18 to 0.32. At the time of CBCT3, the rectum motion was higher than at the time at CBCT2 (Table 1).

At CBCT 2

At CBCT3

p-value

HD95

2.63 [2.15 – 4.54]

4.22 [3.22 – 6.24]

0.011

Rectum prostate

MDTA

1.10 [0.88 – 1.41]

1.61 [1.37 – 2.11]

0.008

HD95

2.40 [1.86 – 3.22]

3.22 [2.15 – 4.23]

0.002

Rectum rectum

MDTA

0.89 [0.71 -1.19]

1.07 [0.85 – 1.51]

0.003

HD95

2.15 [1.52 – 2.40]

2.40 [2.15 – 3.22]

0.006

Tumour wall

MDTA

0.82 [0.62 -0.95]

0.93 [0.74 – 1.13]

0.005

Table 1: Evolution of rectum motion from the CBCT1 to the CBCT2 and to the CBCT3.For all groups of structures evaluated and both HD95 and MDTA metrics (median [interquartile range], in mm), the motion of the rectum is significantly higher at the time of the CBCT3 than the CBCT2.

Wilcoxon test, p-value < 0.05 is significant.

The intrafraction rectum motion is significantly higher for the rectumprostate (median values of HD95 [interquartile range]: 3.22 [2.21 – 5.86], and MDTA: 1.29 [0.94 – 2.00] mm), than for the rectumrectum (HD95: 2.40 [2.15 – 3.56], and MDTA: 0.99 [0.79 – 1.35] mm), or the tumour wall (HD95: 2.15 [1.86 – 2.63], and MDTA: 0.85 [0.67 – 1.04] mm, p<0.01, Figure 1).