Breast Screening FAQ

Mammography screening is a low-dose x-ray examination of the breast that can pick up very small breast cancers. During mammography screening, the breast is gently flattened between two plates of the X-ray machine for a few seconds, to spread the tissue apart and get a good image of the breast.

Images of the breast are taken and developed by a radiographer (a technician) who then hands the X-ray films to a radiologist (a doctor) to check for abnormalities.

It is recommended that women aged over 40 should go for mammography screening once every 2 years.


  1. I’ve already had my breasts examined during the whole body check-up/gynaecological check-up. Does it mean that I don’t need a Breast Screening Programme then?
    An effective and comprehensive breast health check-up exercise should include Self-Breast Examination, Clinical Breast Examination and Mammography Screening. A general body check-up or gynaecological check-up package may not necessarily include these three modalities. To safeguard breast health and protect yourself from the threats of breast cancer, the best way is to start your regular Breast Screening Programme as we recommend.

  2. How does the mammography screening work?
    During the process, you will have to expose your upper body and stand in front of a mammography screening machine. The female radiographer will help put your breast on a platform with an X-ray negative. Plastic sheets will move downwards and horizontally to press the breast so that an X-ray radiograph of the breast tissues can be taken. You might feel uncomfortable for a few seconds when the pressure is applied. One breast is done at a time, allowing two different views of radiograph for each breast. This constitutes a comprehensive examination.

    The radiographer needs to confirm that the X-ray radiographs clearly show the breast tissues, and sometimes more images need to be taken. A report is written by a radiologist. If the X-ray radiographs show any tumours or abnormal images, the doctor will follow up.

  3. Is mammography screening safe?
    As an internationally recognized tool for detecting breast cancer, the mammogram can detect abnormalities which cannot be seen by the eye or felt by the hand. The benefits of saving a life by early detection are much greater than the risks of radiation. In fact, the radiation risk is very low, with a dose of about 0.36 millisieverts per test, which is equivalent to one-eighth of the radiation absorbed annually from natural background radiation, or the radiation exposure from four round-trip flights between Hong Kong and London. (Source: Radiation Health Unit of the Department of Health)

  4. Why do women over 40 need mammography screening every two years?
    The incidence rate of breast cancer increases among women aged over 40. Research has proven that screening can reduce the breast cancer mortality by 20 -30 percent, due to early detection and treatment.

  5. Can ultrasound imaging substitute for mammography screening?
    No. The principles and functions of the two imaging methods are different. They cannot replace each other but are mutually complementary.

    Ultrasound imaging transmits high-frequency sound waves to the breast tissues through an apparatus, and then converts the feedback from the sound waves into an image. Ultrasound can distinguish between a substantial tumour and a cyst, but only mammography screening can detect a tumour which has not yet fully developed, and only a mammogram can detect cancerous cells in the micro-calcification.

  6. When is an ultrasound imaging needed?
    The image of dense tissues may sometimes be unclear on a mammogram. A doctor generally uses ultrasound imaging to examine the breasts of younger women under the age of 40, whose breast tissue is generally higher in density.

    Ultrasound imaging does not release radiation. It is suitable for pregnant women. It can act as a diagnostic tool.
    - if a mass is detected in a breast through palpation, but no images are shown in the mammogram, the doctor will use ultrasound imaging.
    - if a mass is detected in a mammogram, the doctor may use ultrasound imaging to determine whether the mass is a hard substance or a cyst.
    - during extraction of tissue from a mass for tests, the doctor sometimes uses ultrasound imaging as a tool to identify the location.

  7. If micro-calcification or a lump is found inside the breast on a mammogram or in ultrasound screening, what should I do?
    If a lump is found inside the breast through the mammogram or ultrasound screening, the doctor will extract samples of cells from the lump for diagnosis. If the results show that a tumour is malignant, the doctor will conduct further tests to identify the stage of breast cancer and will suggest appropriate treatment options. If the mass is benign, the doctor will propose follow-up actions or treatments.


If you are aged 40 and above, please make an appointment for a mammogram screening here.