ESTRO 2023 - Abstract Book

S1666

Digital Posters

ESTRO 2023

Results Table 1 shows the results of the uncertainty plan (A) regarding CTV and PTV coverage as the number of patients for whom the resulting dose distribution fulfils a coverage of the CTV and PTV within 3 or 5% with respect to the approved plan. For the CBCT recalculation (B) the number of patients that would fulfil the criteria of CTV and PTV coverage in all the fractions is shown. We found a 90% false positive 2D IVD results for 3DCRT and IMRT** and 50% for VMAT**. The agreement for the CBCT dose recalculation was better than 90% for all treatment fractions and techniques. Results for the CTV and PTV coverage for two different patients are shown in figure 1 as an example. Fig. 2 shows the dose reduction for the different techniques compared to 3DCRT as well as its robustness to changes in patient positioning.

D98%plan ± (x) 3DCRT IMRT IMRT* IMRT** VMAT VMAT* VMAT*

A CTV 3% A CTV 5% A PTV 3% A PTV 5% B CTV 1% B CTV 2% B PTV 1% B PTV 2%

7

6

9

10 10

4 6 0 0 0 4 0 1

5 7 0 0 2 6 0 2

4 5 0 0 1 3 0 1

10

10 10

4 7 4 6 1 1

1 2 1 3 1 1

1 1 2 6 2 2

1 1 2 3 1 3

Table 1