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A mammogram is a procedure that uses low-dose x-rays to image breasts. Mammograms are used to aid in the early detection and diagnosis of breast diseases in women and men.

Mammograms are used as a screening tool to detect early breast cancer in women experiencing no symptoms and to detect and diagnose breast disease in women experiencing symptoms such as a lump, pain or nipple discharge.

Mammograms are performed by Medical Radiation Technologists with specific training in mammography

The Ontario Breast Screening Program (OBSP) is offered at all Trillium Health Partners locations.

Who We Help

Women Eligible for Screening in the OBSP:

  • Ontario residents
  • 50 years of age and over
  • No acute breast symptoms
  • No personal history of breast cancer
  • No breast implants

Please note: Patients who have had a previous mammogram through their family physician or are already in the OBSP program, it must have been at least 1 year since their last mammogram to qualify.

Contact Information

To book or find out the status of your appointment, please contact:

Mississauga Hospital or Queensway Health Centre
Phone: 416-521-4069
Fax: 416-521-4014

Credit Valley Hospital
Phone: 905-813-2731
Fax: 905-813-4418


A referral from a doctor is required.

Resources for Patients & Their Families

How to Prepare for Your Procedure

  • The best time for a mammogram is one week following your period.
  • Do not schedule your mammogram for the week before your period if your breasts are usually tender during this time.
  • Always inform your doctor or x-ray technologist if there is any possibility that you are pregnant.
  • Please allow a minimum of 30 minutes for your appointment.
  • Do not wear deodorant, talcum powder or lotion under your arms or on your breasts on the day of the exam. These can appear on the mammogram as calcium spots.
  • Wear a 2 piece outfit.
  • Describe any breast symptoms or problems to the technologist performing the exam.
  • If possible, obtain prior mammograms and make them available to the radiologist at the time of the current exam.

What to Expect from Your Procedure

  • A specially qualified radiology technologist will position your breast in the mammography unit.
  • Your breast will be placed on a special platform and compressed with a paddle (often made of clear Plexiglas or other plastic). The technologist will gradually compress your breast.
  • You will be asked to change positions between images. The routine views are a top-to-bottom view and an oblique side view. The process will be repeated for the other breast.
  • You must hold very still and may be asked to keep from breathing for a few seconds while the x-ray picture is taken to reduce the possibility of a blurred image.
  • The technologist will walk behind a wall or into the next room to activate the x-ray machine
  • When the examination is complete, you will be asked to wait until the radiologist determines that all the necessary images have been obtained.
  • The examination process should take about 30 minutes.

How It Works

The mammogram compresses the breast to even out the breast thickness so that all of the tissue can be visualized and hold it still to minimize blurring of the image caused by movement.
Spreading out the tissue makes it less likely for small abnormalities to be obscured by overlying breast tissue

It also allows the use of a lower x-ray dose since a thinner amount of breast tissue is being imaged.