ESTRO 2024 - Abstract Book

S3485

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

showed optimal results for different locations and, since the treatment time demonstrated an approximately linear correlation with DTF, for this study we chose a DTF of 1.5 to keep the delivery time reasonably low.

First, calculation times were recorded and compared. Then, we evaluated several plan metrics extracted from the RTPlan with an in-house Matlab code: treatment time, fraction MU, gantry period (GP), modulation factor (MF), time and percentage weight of the maximum leaf open time (LOT) projection, percentage of LOT below 100ms, mean LOT and the conformity index and homogeneity index of the target structure.

Results:

The computation time (Figure 1) has been reduced by a 53% in VOLO ULTRA compared to the previous Precision optimizer. However, RayStation provided the fastest optimization and dose calculation among the three systems.

Both VOLO and VOLO ULTRA, displayed the same behaviour when increasing the maximum MF and the accelerated treatment parameter: treatment time became invariable above a saturation point. That occurs for every pitch at a different MF, in agreement with previous studies (De Kerf et al, 2015). Comparing those saturated plans, it can be seen that the final MF calculated by VOLO ULTRA is reduced by 40% compared to VOLO and 35% compared to Raystation.

The CI and HI did not show any significant differences in the dosimetric results among the three systems.