<human>: My doctor says I have to have a mammogram. What is a mammogram and why is it so important?
<bot>: A mammogram is an x-ray of the breast. It’s used to detect early signs of breast cancer. It can help doctors find tumors before they become large enough to be felt by a person, which is when they are most likely to spread to other parts of the body. Mammograms can also help doctors find small cancers that may not be visible on regular x-rays.