I have been doing simulations for a 6 MeV LINAC. For this I need to score dose rate. I get energy deposited through usrbin card and then convert it to dose rate incorporating our Pulse width and pulse repetition frequency. But the dose i get through simulation is much less than the dose we measure in lab at 6 MeV LINAC.

So, my question is can we get exact absolute dose through FLUKA Simulations?

Per region [GeV] or through a regular mesh [GeV/cm^3]?

This does not check out: if you multiply GeV/primary (or GeV/(cm^3 primary), see above) by 1.6E-7 mJ/GeV, you get mJ/primary (or mJ/(cm^3 primary)), which is not a dose. The density [g/cm^3] of the scoring material has to be included in the equation.

What is the difference that you see?
What are the uncertainties on the results of the measurements and of the simulations?
Did you take into account the volumes?

Also, it would be good if you could share your input.

I get dose deposited about 10 cGy/min after calculation but in actual for 100 HZ PRF with 100 mA current, we measure 80 cGy/min dose in lab. I am sharing here my input file. Linac6.flair (5.2 KB)

Dear @ceruttif what specifications should I use in the beam card?? As I have a beam spot of 6MeV electrons coming out from electron gun. The diameter of beam spot is 3mm with guassian distribution.

Have you tried looking at the Simple Source lecture from the last course for beginner?
Or at the BEAM card manual?
There it is well explained how to define a simple beam like the one you want to simulate.