Radiation

Radiation

Screening mammograms and their radiation risks

Natural background radiation

Radiation occurs naturally all around us from sources such as the sun, rocks, soil, buildings, air, food and drink. This is known as ‘background radiation dose’.

The scientific unit of measurement for radiation dose is millisieverts (mSv). In Australia the average background radiation dose is about 2.0 mSv per year.

Diagnostic imaging and radiation

X-rays are a form of ionising radiation which penetrates the body to form pictures on film or digital imaging (eg. a computer screen). This type of radiation is used widely in medical facilities to perform diagnostic imaging procedures.

X-rays provide valuable information about the inside of your body and are important in helping your doctor make an accurate diagnosis.

Diagnostic imaging with no radiation

Other forms of diagnostic imaging such as magnetic resonance imaging (MRI) and ultrasound are procedures that do not expose you to ionising radiation.

Radiation exposure

Studies have linked high doses of ionising radiation (>50mSv) to an increased risk of cancer. Living cells can be damaged by X-rays.  However, the risk is extremely low with the radiation dose you will receive from a mammogram.

Table 1 compares the radiation dose of a screening mammogram, (which involves 2 X-rays of each breast), to other imaging tests.

Radiology

Typical effective
dose (mSv)

Equivalent period of natural background  radiation

X-ray Examination

Chest

0.02

5 days

Mammogram

0.7

24 weeks

Abdomen

0.7

24 weeks

Pelvis

0.7

24 weeks

Lumbar spine

1.0

35 weeks

CT Examination

Head

2.0

1.3 years

Chest

8.0

5.3 years

Abdomen

10.0

6.7 years

Table 1 Source: Towards appropriate use of diagnostic imaging: A guide for medical practitioners and their patients. Cancer Council WA, 2011.

Screening mammography and radiation

A screening mammogram is an X-ray of the breast tissue for women without any breast symptoms. It uses low doses of radiation (about 0.7mSv for 4 X-rays).                                                                         

X-ray safety

X-rays are produced only when a switch is momentarily turned on, like a light switch. No radiation remains after the switch is turned off.

BreastScreen WA contracts licensed medical physicists (a scientist specialising in physics in medicine) to routinely evaluate the radiation dose from X-ray equipment used to ensure it is as low as possible and does not exceed regulatory limits.

Factors affecting X-ray dose

The radiation dose from a screening mammogram is the amount of X-rays that are absorbed in the breast tissue. Two of the major factors affecting radiation dose are the amount of compression and the thickness and structure of the breast.           

Breast compression during a screening mammogram reduces the radiation dose significantly since a thinner amount of breast tissue absorbs less radiation. It also separates overlapping folds of breast tissue that may obscure small abnormalities.

Breast implants can block a clear view of the breast tissue making mammograms less effective in breast cancer detection.

Therefore, radiation exposure will be greater in women with implants, because more X-rays need to be taken (between 6 - 8) and less compression is used.

Risks and benefits

Risks

The risk of getting cancer from a screening mammogram is considered to be very low. Table 2 below shows the additional risk in a person’s lifetime of developing cancer from X-ray procedures at each examination.

Examination Lifetime additional risk of cancer per exam*
  Negligible Risk
Chest, teeth, arms & legs, hands & feet x-rays Less than 1 in 1,000,000

 

Minimal Risk

Skull, head, neck x-rays 1 in 1,000,000 to
1 in 100,000
  Very Low Risk

hip, spine, abdomen, pelvis x-rays, CT head, breast mammography

1 in 100,000 to
1 in 10,000

  Low Risk

Kidney & bladder [IVU], Stomach – barium meal, CT chest, CT abdomen

1 in 10,000 to 1 in 1,000

Table 2 Source: Adapted from UK National Radiological Protection Board (2001).

* These risk levels represent very small additions to the 1 in 3 chance we all have of getting cancer throughout our life time.

If you are pregnant, it is advisable you postpone your screening mammogram until after the birth. A screening mammogram is not recommended for women who suspect they are pregnant.

Benefits

The low dose of radiation used in a screening mammogram has not been proven to cause harmful effects. The benefit of early diagnosis and treatment of breast cancer far outweighs the risk of the small amount of radiation received during a screening mammogram.

How often should I have a mammogram?

At least every two years unless there are reasons for more frequent mammograms. If breast cancer is detected early, there is a good chance it can be treated successfully.

Book online or phone 13 20 50

When making your appointment, please let us know if you

  1. have breast implants
  2. require an interpreter
  3. use a wheelchair.

These things may make your appointment a little longer.

If you need an interpreter, please call the Translating and Interpreting Service (TIS) first on 13 14 50 and ask to be connected to the BreastScreen WA call centre on 13 20 50.

NOTE:

Wheelchair access is available at all BreastScreen WA services.

Appointments are available 7:30am-5:45pm on weekdays and 8:15-11:30am on Saturdays at most BreastScreen WA clinics.

BreastScreen WA has metropolitan, regional and mobile screening services located at:

Bunbury South West Health Campus
Corner of Bussell Highway and Robertson Drive

Cannington      Unit 15, Prime West Cannington,
                         1490 Albany Highway, Beckenham, 6107

Cockburn Cockburn Integrated Health and Community Facility,
                        Suite 4, Corner Beeliar Drive and Wentworth Parade, Success, 6164

David Jones Rose Clinic
Level 3, Perth City store, 6000  

Mandurah Level 1, 3/61 Sutton Street, Mandurah 6210

Midland 14/27 Old Great Northern Highway, Midland, 6056

Mirrabooka      29 Yirrigan Drive, Mirrabooka, 6061

Padbury           Hepburn Heights Shopping Centre,
 Unit 8/6 Blackwattle Parade, Padbury, 6025

Perth City        50 Murray Street, Perth, 6000

Rockingham    Unit 2, 12 Leghorn Street, Rockingham, 6168

Wanneroo       ECU Health Centre, L2
30 Dundebar Road, Wanneroo, 6065

Appointments are available 7:30am-5:45pm on weekdays and 8:15am-11:30am on Saturdays at most BreastScreen WA clinics.

Mobile breast screening services visit outer metropolitan areas and country towns every two years. Some towns are visited annually.

  • Please bring your Medicare card with you to your appointment.
  • Women whose breasts become tender before their periods find it more comfortable to have a mammogram during or just after a period.
  • If you’ve had a previous mammogram elsewhere, please bring these images with you.
  • Please don’t wear talcum powder or deodorant on the day of your appointment. It may show on the X-ray picture.
  • Please be aware you will be reading information and signing a consent form at the appointment.

Get to know your breasts and what is normal for you. Look in the mirror at your breasts and feel your breasts from time to time.

If you notice any unusual changes in your breasts such as lumps, nipple discharge, or persistent new breast pain, even if your last screening mammogram was normal, please see your GP promptly.

Ask your GP to check your breasts regularly.

Contact your GP or phone:

BreastScreen WA

13 20 50 for appointments

(08) 9323 6700 for information or

1800 800 033 toll-free for country women

National Relay Service

Last Updated: 27/05/2014