How to label segmented organs?

I want to calculate a dose absorption for some organs from PET and CT images. for this goal, I need to label segimented organs. which module can help me?
thank you.

You can segment (a.k.a. label, contour) images using Segment Editor module.

hi again
I require to produce a dat file for assessing dose by GATE. an example of dat file:
1 1 kidney
2 2 spleen
I require to assess dose in these organs. in addition of dat file, GATE needs images.
I don’t know how to produce this interfile.
can you any guidance to me?
Thank you.

Gate can use MetaImages (mhd) images as long as they are uncompressed. you can save youir images in that way