Skip to main content

What is a Mammogram?


Video available in English, Cantonese, Mandarin & Punjabi

Mammograms are x-rays of the breasts completed in privacy by a specially-trained female technologist.

A screening mammogram consists of four images (two of each breast) that look for hidden cancer in those who are healthy (no symptoms) and have never had breast cancer.

If you are experiencing symptoms including a lump or nipple discharge, you should see your health care provider immediately to determine if other testing is required.

What to expect during your first mammogram


Video available in English, Cantonese, Mandarin & Punjabi

Why do the breasts get compressed during a mammogram?


Video available in English, Cantonese, Mandarin & Punjabi

Why do you need regular mammograms?


Video available in English, Cantonese, Mandarin & Punjabi

Your questions

Body Mass Index (height and weight) has been recognized as a risk factor for breast cancer.  BC Cancer Breast Screening has begun to collect this information to assist in assessing an individual’s breast cancer risk so that it may guide screening accordingly.

How does this affect your appointment?
The technologist will ask if she may measure your height and weight before your mammogram which will be documented on your confidential history form.  

How long will this take?
It shouldn’t take more than a minute for the technologist to measure your height and weight.

Is this a required part of the screening mammogram?
We respect that agreeing to height and weight measurement is an individual decision, just as breast screening is, and it is in no way conditional to you having a screening mammogram. Please remember that all data that the screening program collects is completely confidential.

Where can you find more information about this?
BC Cancer Breast Screening collects personal information under the authority of the Health Act and section 26(c) of the Freedom of Information and Protection of Privacy Act (FIPPA). 
BC Cancer Breast Screening doesn't recommend the use of thyroid guards for screening mammograms because they can interfere with capturing a clear breast image. The guard can limit the technologist’s ability to place all of the breast tissue on the compression plate. As a result, some breast tissue may be missed or more x-rays may need to be taken. 

Also, the screening mammography x-ray directs the radiation beam towards the breast tissue, so the thyroid isn't directly exposed to the radiation beam. The thyroid can be exposed to "background scatter radiation”, which is the same amount of radiation a North American would be exposed to from 30 minutes of natural background radiation. 

At this time, only essential companions are permitted. An essential companion is someone considered paramount to the patient's physical care and mental well-being.‎


Screening mammograms can find most types of breast cancer early, but like all screening tests, they aren't perfect. Some cancers can't be seen on an x-ray and some cancers can develop quickly between 2-year intervals. Learn more about the benefits and limitations of screening mammography.


Screening mammograms are for those with no symptoms of breast cancer (no apparent breast problems). Diagnostic mammograms are ordered by a doctor to look at an area of concern in the breast; which may lead to more tests; such as an ultrasound or a biopsy.

The effectiveness of screening mammography has been well established by several large clinical trials across the world. These trials have found a relative risk reduction of breast cancer deaths of between 15-25% for women aged 50-69. Of eight randomized control trials for screening mammography, seven showed that screening mammography is beneficial.

In February 2014, the British Medical Journal published 25-year follow-up results from the Canadian National Breast Screening Study – the only randomized control trial suggesting that annual screening in women age 40-59 does not reduce breast cancer mortality beyond that of physical examination (for the 50-59-year-olds) or usual care (for 40-49-year-olds). BC Cancer does not agree with the findings in this study, and other credible evidence does not correlate with the findings.

Tomosynthesis is a new technology available to improve investigation of breast problems. The quality of all mammograms in the BC Cancer Breast Screening program is of the highest standard. Further assessment is needed to determine the optimal use of breast tomosynthesis in breast health. Until more information is available, the primary use of this technology will remain in the diagnostic setting.

Woman looking at phone with computer in front of her
​Book a mammogram
Find your closest screening location and book by phone or online

SOURCE: What is a Mammogram? ( )
Page printed: . Unofficial document if printed. Please refer to SOURCE for latest information.

Copyright © Provincial Health Services Authority. All Rights Reserved.

    Copyright © 2024 Provincial Health Services Authority