ESTRO 2024 - Abstract Book

S2905

Interdiscplinary - Other

ESTRO 2024

Fig. 2: PyCT , data evaluation section. On the left, variables are selected for analysis. Statistical data values are shown in the table below. Further down, parameters for multi-functional filtering are defined. The centre shows a histogram chart displaying the CTDI for the region abdomen & pelvis, with markings for the 75th percentile, the median value and the dDRL. 1,837 CTs of adults (>12 years) acquired between 15th June 2021 and 22nd March 2023 were analysed. Table 1 lists the number of CTs for each scan region. dDRLs usually include the CTDI and the scan length (previously the Dose Length Product, DLP). Scan lengths in radiotherapy are often larger than in diagnostics, since planning CTs are used to calculate treatment dose taking photon scattering into account. Furthermore, they often include immobilisation devices such as head masks. Due to these differences, this analysis focuses on the CTDI. For the comparison to dDRLs which correspond to the 75th percentile of a data sample, we report the 75th percentile of locally obtained CTDIs, as well as medians and standard deviations.