Wikipedia describes the process used in a Mammography this way:

During the procedure, the breast is compressed by a dedicated mammography machine to even out the tissue, to increase image quality, and to hold the breast still (preventing motion blur). Both front and side images of the breast are taken.

Notice it says the breast is compressed? Wow! I'll say. I always expect to find bruises the next day, but I've never seen any. But there's no doubt that, if not really painful, it's downright uncomfortable.

Well, we women may not have to suffer through mammograms if a new test method of analysis proves out. A story in the Geelong Advertiser out of Australia tells us:

DETECTING breast cancer could soon be a simple as analysing a strand of hair, if a new method being trialled in Geelong proves successful.

Nurses at the medical imaging clinic have already begun collecting strands of hair from women taking part in the trial.

These strands are then sent to Chicago where researchers use a powerful X-ray microscope called a synchrotron to look for minute differences in the hair structure which indicate the presence of breast cancer.

Sounds much quicker and simpler than mammography. Quoting the Advertiser, the results so far are "very, very good" and if all goes well, the test could be available in Australia within the year.