DEAR DR. DONOHUE: I am due to have a mammogram in July, but around the same time I am supposed to have a chest CT as a follow-up to my chondrosarcoma cancer. I have a CT every other year, and an X-ray on the opposite years of both my affected arm and my lungs. Does a chest CT have the potential of showing a similar finding as a mammogram? I would just as soon not have to expose myself to so much radiation all in one month. I'm 66. There is a history of postmenopausal breast cancer in my family, in my mother's mother. -- T.M.H.
ANSWER: A mammogram is an X-ray that is designed specifically to look for abnormalities in breast tissue. Mammograms have been extensively studied and proven to reduce mortality in women between the ages of 50-74 (outside these ages, there remains extreme controversy).