ESTRO 2024 - Abstract Book

S3962

Physics - Image acquisition and processing

ESTRO 2024

For pelvis and brain cohorts, average ME values were respectively 1 ±8 HU and -9 ±10 HU for body contour, 2 ±7 HU and -14 ±9 HU for soft-tissue and 43 ±66 HU and 107 ±51 HU for bone. Figure 1 presents ME values obtained for different organs of the evaluated cohorts. Average Mean Absolute Error (MAE) values were also calculated per cohort : pelvis (109 ±11 HU; 31 ±9 HU; 153 ±25 HU) and brain (40 ±7 HU; 20 ±10 HU; 274 ±29 HU) respectively for body, soft and bone tissue. Significant differences were always observed for bone regions (pelvic bones and skull).

Figure 1 : Average ME values (HU) calculated for different regions and organs of interest for pelvis and brain cohorts

Figure 2 : Dose deviations (Gy) (sCT minus CT) for different target volumes (D95%, D2%) and organs at risk (Dmean)

Mean dose differences (Gy) for all criteria to OARs and target volumes were less than 0.5Gy for brain and pelvis cohorts (Figure 2) and all the deviations observed were mainly less than 1 Gy for all organs assessed. None of the observed deviations lead to non-compliance with clinical validation criteria. Mean 3D gamma passing rates at 2%/2mm (threshold 10%) were 96.3% and 99,3% respectively for pelvis and brain cohorts.