The tech is available with most modern CT scanners used on people. Slices of about 0.5 mm are easy to achieve (without massive doses of radiation), and 3D work like that can be done fairly easily (I'm a radiologist, and I do things like that daily).
The main difference between the mummy and (living) people is you can decrease the slice-thickness of each image (which makes the reconstructed images look better) by increasing the radiation dose. Don't like to do that to people... too much.