ESTRO 2024 - Abstract Book

S3689

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

ESTRO 2024

Dn/Dp = [1 + Φ -1 (1-NTCPp)×SD%(Dp)] / [1 + Φ -1 (1-NTCPn)×SD%(Dn)] = C,

(3)

with SD%(x)=SD(x)/x the relative variation in percentage. The ratio Dn/Dp is the reRT change factor C. The consequences of this recipe will be studied for different values of NTCP and SD(D).

Results:

In Fig.1 two examples of Timmerman dose constraints as function of nf are depicted and compared with the LQ model. Using the standard α/β=3Gy, conversion curves deviate significantly from the clinical data (RMSE=10-30%), but using fitted α/β the RMSE<4%. The data below show the fits for all OARs with equal critical volumes for all nf (Dmax or dose-volume). Average α/β becomes 6-9Gy, but there are significant outliers.