Imaging study · Low dose
Mammography
Also known as: mammogram, breast screening, breast X-ray, tomosynthesis
A low-dose X-ray of the compressed breast that can detect cancers years before they can be felt, used for screening programmes and for investigating breast symptoms.
How it works
A low-dose X-ray of each breast, compressed between two plates for a few seconds to spread the tissue thin and hold it still. Two views are taken of each side. Digital tomosynthesis takes a sweep of images to reconstruct thin slices, reducing overlap. Cancers show as masses, distortions or clusters of tiny calcifications, often years before they can be felt.
What it shows
- Breast cancer, including ductal carcinoma in situ (calcifications)
- Benign lumps: cysts, fibroadenomas (with ultrasound to tell them apart)
- Breast density, which affects both risk and how easily cancers are seen
Best for
- Population screening of women aged roughly 50-70, every 2-3 years depending on country
- Investigating a new lump, nipple change or skin change in women over 40
- Follow-up after breast cancer treatment
Not the right tool for
- Younger women with dense breasts, where ultrasound and MRI see more
- Assessing implants (MRI)
- Ruling out cancer completely: about 1 in 8 cancers is missed, so a new lump is always investigated even after a normal screen
What to expect
- Modality
- Mammography
- Preparation
- No deodorant or talc on the day (they mimic calcifications); book after a period if breasts are tender.
- Duration
- About 10-15 minutes, with each compression lasting a few seconds.
- Radiation
- About 0.4 mSv for two views of both breasts, similar to seven weeks of natural background radiation.
- Contrast
- Contrast-enhanced mammography with iodine is an emerging alternative to breast MRI.
- Risks
- Discomfort from compression; a small radiation dose; false alarms leading to recalls and biopsies; overdiagnosis of cancers that would never have caused harm.
Common uses
| Region | Typical question |
|---|---|
| Screening | Asymptomatic women in the screening age range |
| Symptomatic | Lump, discharge, dimpling, in a one-stop clinic with examination, ultrasound and needle biopsy |
| High risk | Earlier and yearly screening for BRCA carriers, usually with MRI |
Studies this page covers
Named studies of the master test taxonomy that this modality page covers; each links to its test category.