# Geometry rotation

Dear fluka experts,
I’m facing an issue when I try to rotate my geometry (60°) in order to measure the dose, using ROT DEFI card.
I already calculated the dose for 0° and the simulation was made without issues. When I used the rotation card my geometry is found to be outside the regROOM region.

dose 60 degree.flair (3.2 KB)

Dear @ibtissam.zidouh,

The problem is that the rotation is defined around the y axis passing for the origin and not around the the y axis at the center of your target.
You need to define your transformation in 3 steps:
1-bring the bodies you want to rotate back to the origin;
2-rotate by whichever angle you want;
3-move the bodies back to wherever you want.

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Dear amario
Thank you so much for your explanation I did the translation back to origin and rotation then get bodies back to initial position but you said in your reply to get my bodies to the origin, does it mean that the center of my body has to be the origin or one of the sides should be the origin. Are both cases correct, do they affect my purpose to measure the dose ?

Both cases are correct in principle. They are similar and yield slightly different results. Which one to choose (or if they are equivalent) depends on what precisely you are aiming at.

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Thanks a lot for your help, I an know able to do my calculations