The meaning of DOSE-H2O

Dear Fluka experts,

As in the title, what does DOSE-H2O score in RAD-BIOL and TPSSORE? what’s the difference between DOSE and DOSE-H2O?
I tried thses two scoring in the same run. There are two materials: first in the front depth of 3 cm; the second material start from the depth of 3 cm to the end. There is an obvious difference in two scores between the two materials, which is marked with the red circle of the figure. Why DOSE-H2O is smooth but DOSE with a decrease?
Thanks in advance for your help.

Best regards,

Jingfang

DOSE-H2O corresponds (as the name says) to dose-to-water, calculated by weighting the tracklength with the stopping power in water at every step (no matter if the material at the step location is different).

While DOSE is calculated as the real energy deposition per mass.

DOSE-H2O is typically used in the medical environment to compare with the output of TPS systems as well for the calculation of the RBE

Please look the post

especially the appendix of the quoted paper.