ESTRO 2025 - Abstract Book

S330

Brachytherapy - Physics

ESTRO 2025

Results:

A total of 30 needles were analysed, and it was found that the difference between the nominal and the measured depth with MR and CT was less than or equal to 1.3 mm in 27 of them. Larger discrepancies were observed in the remaining three needles, with differences of 2 mm, 3 mm, and 4 mm, respectively. For 02 configuration, the average difference was 0.0 mm with a standard deviation of 1.5 mm. For 03 configuration, the average difference was -0.4 mm with a standard deviation of 0.5 mm. For 04 configuration, the average difference was -1.0 mm with a standard deviation of 1.2 mm. Differences in measured lengths below 2 mm are within detectability range due to the CT and MRI slice thickness. So, we have found a good agreement in the needle length measured with CT and MR except for three positions of thirty analysed.