“Screening” means looking for an illness before an individual has any symptoms. The mainly well-known use of medical image screening is for breast cancer. Here are guidelines from NIH’s National Cancer Institute for ruling breast cancer early:

• Women who are younger than 40 and have risk factors for breast cancer (for example, a family record of breast cancer or certain breast changes on biopsy) should discuss how frequent to have mammograms with their health care provider.
• Women 40 and older must have mammograms each 1 to 2 years.
• Plan clinical breast exams as well, to have your health care provider examine your breasts.
• Carry out monthly breast self-exams to test for any changes. Breast self-exams should not replace mammograms and clinical breast exams.

Also read: What Is Breast Screening?