Breast Care A-Z · Procedure · TOMO

Tomosynthesis (3D mammography)

also: 3D mammography, digital breast tomosynthesis, DBT · pronounced toh-moh-SIN-the-sis

Tomosynthesis, or 3D mammography, takes multiple low-dose X-ray images and reconstructs them into thin layers, helping separate overlapping tissue and improve accuracy in dense breasts. You may have been told it is being added to your mammogram, or seen the term in a report — it is widely available in modern breast units.

Quick answers

Is tomosynthesis better than a standard mammogram?

Yes, in specific situations — particularly in dense breast tissue and for characterising lesions whose shape and edges matter. For routine screening of patients with non-dense tissue, standard mammography remains highly effective and adding tomosynthesis offers a modest but real improvement.

Does tomosynthesis use more radiation?

A small amount more than a standard 2D mammogram alone. Modern systems often use a synthesised 2D image generated from the tomosynthesis data, which keeps the total radiation dose similar to a conventional 2D-plus-2D protocol. The dose is well within safety limits in either case.

Can tomosynthesis pick up cancer that a 2D mammogram would miss?

Sometimes, yes — particularly small cancers in dense breast tissue that would be obscured on a 2D image. This is one of the reasons tomosynthesis is increasingly used. It does not pick up everything — MRI is more sensitive for soft-tissue lesions, and some cancers (particularly some lobular cancers) are subtle on any imaging.

Tomosynthesis -- Breastory Encyclopaedia Plate LXXV Plate covering digital breast tomosynthesis (DBT / 3D mammography): acquisition, reconstruction, clinical benefits, and comparison with 2D mammography. RADIOLOGY · DIAGNOSTIC IMAGING PLATE LXXV tomosynthesis digital breast tomosynthesis · DBT · 3D mammography three-dimensional mammographic acquisition that reduces tissue overlap and significantly improves cancer detection and recall rates compared to standard 2D mammography FIG 01 -- 2D mammography vs digital breast tomosynthesis (DBT) 2D Mammography tissue overlap (creates false shadow) X-ray source (single position) flat image detector Single flat image (overlap unresolved) 2D: tissue overlap reduces accuracy DBT (3D Tomosynthesis) lesion clearly isolated flat detector (multiple acquisitions) 1mm slices -- lesion isolated in one plane DBT: arc sweep + 1mm slices + no overlap Synthesised 2D (s2D): reconstructed from DBT data -- replaces standard 2D view, reducing total dose i -- X-ray tube arc motion (±15° sweep) ii -- multiple low-dose acquisitions (15 angles) iii -- reconstructed 1mm slices (no tissue overlap) iv -- improved lesion conspicuity v -- synthesised 2D image from DBT data (reducing dose) How DBT works Arc: X-ray tube moves ±15° acquiring 15 images Dose: Each acquisition at low dose Reconstruction: Computer builds multiple ~1mm slices Total dose: ~2x standard mammogram Mitigated: Synthetic 2D replaces standard view Result: Tissue overlap eliminated Clinical benefits Detection: ~20-40% more cancers vs 2D Recall reduction: ~15-30% fewer false recalls Arch. distortion: Significantly better detected Dense breasts: Overcomes tissue overlap FIG 02 -- 2D mammography vs DBT: detailed comparison Feature 2D Mammography DBT (3D) Images produced Single flat image per view Multiple 1mm slices per view Tissue overlap Yes -- reduces sensitivity Eliminated Recall rate ~5% ~3-4% (reduced) Cancer detection Standard +20-40% relative improvement Arch. distortion Often missed Much better detected Radiation dose 1x ~1.5-2x (reduced by synthetic 2D) Calcifications Well-detected Equal (sometimes better) Dense breasts Limited Improved Scan time Shorter Slightly longer Availability Widespread (standard NHS) Growing but not universal FIG 03 -- DBT indications, benefits, and evidence Indication Benefit Evidence Dense breasts Overcomes tissue overlap High Architectural distortion Superior detection High ILC detection Better than 2D Moderate Screening Reduced recalls STORM, OSLO trials Diagnostic workup Characterise mammographic findings High Heterogeneous tissue Resolves summation artefacts High Prior cancer Detection of second primaries Moderate High-risk surveillance As adjunct to MRI Emerging Screening programme NHS pilot (OPTIMAM) Ongoing FIG 04 -- DBT screening and diagnostic pathway 1 Woman attends screening 2 DBT acquisition (CC + MLO views with arc sweep) 3 Computer reconstruction (1mm slices) 4 Radiologist reads DBT slices + synthetic 2D 5 If abnormality: BI-RADS category assigned 6 Recall if BI-RADS 3-5 -- Assessment clinic FIG 05 -- DBT modes and applications DBT (standard 2-view) DBT + synthetic 2D (s2D) Combo mode (DBT + FFDM) DBT-guided biopsy DBT for architectural distortion DBT in dense breasts FIG 06 -- Key statistics ~20-40% more cancers detected vs 2D [1] ~15-30% reduction in false recall rate [2] Architectural distortion detection significantly improved [3] NHS OPTIMAM programme ongoing evaluation [4] References 1. Friedewald SM et al. DBT screening. JAMA 2014;311:2499 2. Ciatto S et al. STORM trial. Lancet Oncol 2013;14:583 3. Svahn TM et al. OSLO tomosynthesis trial. Radiology 2012 4. NICE NG12. Suspected cancer 2023 5. NHS England. OPTIMAM DBT programme 2023 Clinically authored by Dr Fiona Tsang-Wright , FRCS (Gen Surg) GMC 4549831 · ORCID 0000-0003-4801-026X
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Definition
Tomosynthesis is a refinement of mammography that takes multiple thin-slice X-ray images of the breast at different angles and reconstructs them into a 3D image, improving the detection of cancers in dense breast tissue and reducing unnecessary recalls.

Common questions The questions patients ask first

Is tomosynthesis better than a standard mammogram?
Yes, in specific situations — particularly in dense breast tissue and for characterising lesions whose shape and edges matter. For routine screening of patients with non-dense tissue, standard mammography remains highly effective and adding tomosynthesis offers a modest but real improvement.
Does tomosynthesis use more radiation?
A small amount more than a standard 2D mammogram alone. Modern systems often use a synthesised 2D image generated from the tomosynthesis data, which keeps the total radiation dose similar to a conventional 2D-plus-2D protocol. The dose is well within safety limits in either case.
Can tomosynthesis pick up cancer that a 2D mammogram would miss?
Sometimes, yes — particularly small cancers in dense breast tissue that would be obscured on a 2D image. This is one of the reasons tomosynthesis is increasingly used. It does not pick up everything — MRI is more sensitive for soft-tissue lesions, and some cancers (particularly some lobular cancers) are subtle on any imaging.
Will I need an extra appointment for tomosynthesis?
No — tomosynthesis is performed on the same machine, in the same appointment, as standard mammography. It is part of the imaging protocol rather than a separate test.

Tomosynthesis is a refinement of mammography that takes multiple thin-slice X-ray images of the breast at different angles and reconstructs them into a 3D image, improving the detection of cancers in dense breast tissue and reducing unnecessary recalls.

Tomosynthesis is performed on the same machine as a standard mammogram — the patient experience is essentially identical. The difference is what the machine does: instead of one image per view, the X-ray tube sweeps through an arc and captures many thin slices, which the radiologist reads as a 3D reconstruction. Particularly useful in dense breast tissue and increasingly part of the standard mammographic toolkit.

Orientation Why you might be reading about this

You may have been told that tomosynthesis is being added to your mammogram, or you have seen the term in a report. The technology is widely available in modern breast units and improves diagnostic accuracy in specific situations. This page explains how it differs from a standard mammogram and when it is most useful.

Related terms: Mammogram · Microcalcifications · Core biopsy · Breast MRI

How it differs How tomosynthesis differs from standard mammography

A standard 2D mammogram takes a single X-ray image of the breast from each angle (typically two views: top-to-bottom and side-to-side). The image is essentially a flattened projection of the entire breast thickness — overlapping tissue can hide small abnormalities or create false impressions of abnormalities that are not really there.

Tomosynthesis takes the same patient position and the same compression but adds a different acquisition: the X-ray tube sweeps through a small arc above the breast, taking many thin-slice images at different angles. A computer reconstructs these slices into a series of slices typically around 1 mm thick through the breast, which the radiologist reads slice by slice — like turning the pages of a book.

The result is a more detailed view that distinguishes overlapping tissue layers, particularly useful when:

  • Breast tissue is dense — younger women and a meaningful proportion of older women have dense breast tissue that obscures small lesions on standard mammograms.
  • There is a question about whether something is real — tomosynthesis distinguishes overlapping normal tissue (which “disappears” between slices) from a true lesion (which remains visible across multiple slices).
  • A small lesion needs to be characterised — its precise shape and edges can be assessed more reliably.

What it improves What it improves

Compared to standard 2D mammography alone, tomosynthesis:

  • Improves cancer detection — particularly in denser breasts. Large screening studies show a relative improvement in cancer detection rate of approximately 20–30% when tomosynthesis is added to standard mammography13 — benefit is concentrated in dense breasts. The UK TOMMY trial in NHS assessment clinics showed a modest sensitivity gain but a meaningful improvement in specificity and recall reduction.
  • Reduces recall rates — fewer patients are called back for further imaging after a tomosynthesis-included screening, because the radiologist can resolve apparent abnormalities that turn out to be overlapping normal tissue3.
  • Better characterises calcifications — the slice-by-slice review helps distinguish benign-pattern calcifications from those needing biopsy4.

Limitations What it does not change

  • Microcalcification detection — already a strength of standard mammography. Tomosynthesis is similar to standard mammography for detecting microcalcifications themselves, though it sometimes helps characterise their pattern.
  • Radiation exposure — modern tomosynthesis adds a modest amount of additional radiation compared to a standard 2D mammogram alone, though some systems use a synthesised 2D image generated from the tomosynthesis data to keep total dose similar to a standard 2D-plus-2D protocol.
  • Need for biopsy — tomosynthesis identifies areas that may need a biopsy more accurately, but the biopsy itself is still needed for definitive diagnosis.

Availability Where tomosynthesis is offered

Tomosynthesis is widely available in UK breast units — both NHS specialist centres and private hospitals4. Most modern mammography machines have tomosynthesis capability, and it is increasingly part of the standard breast imaging protocol.

Within the NHS Breast Screening Programme, digital breast tomosynthesis (DBT) is not used for routine screening outside approved research trials (notably the ongoing PROSPECTS trial, recruiting around 100,000 women); the UK evidence base includes the completed TOMMY trial and PROSPECTS2. DBT is used in NHS assessment and symptomatic clinics. In private practice and one-stop clinics, tomosynthesis is often added when clinically useful — particularly for symptomatic patients with dense breasts4.

Patient experience What the patient experience is like

For the patient, tomosynthesis feels like a standard mammogram:

  • Same machine — the X-ray equipment and positioning are essentially identical.
  • Same compression — the breast is compressed against a flat plate, briefly and uncomfortably, the same way as a standard mammogram.
  • Slightly longer per view — the sweep takes a few extra seconds compared to a single 2D exposure.
  • Same total appointment time — typically 15–20 minutes.
  • Results — usually available within 1–2 weeks for screening2; the same day for symptomatic one-stop assessment.

There is no separate preparation, no contrast injection, no additional appointment. The tomosynthesis component is simply built into the imaging protocol.

At consultation What to discuss at consultation

If your imaging includes tomosynthesis:

  • Whether tomosynthesis is being added to standard mammography or used alone.
  • What the radiologist is looking for — particularly in dense breast tissue.
  • Whether further imaging or biopsy is indicated based on the findings.
  • Future surveillance — whether tomosynthesis will be part of your routine imaging going forward.

Resources Further reading

Sources & guidance

Every figure on this page is anchored to a published source. Tap a number in the text or below to jump to the reference.

  1. trial Skaane P, Bandos AI, Gullien R, et al. Comparison of digital mammography alone and digital mammography plus tomosynthesis in a population-based screening program. Radiology. 2013 ;267(1):47-56 doi:10.1148/radiol.12121373 Cited for: Tomosynthesis improves cancer detection by ~20-30% over 2D mammography in screening.
  2. programme Public Health England / NHS England. NHS Breast Screening Programme. London: gov.uk. 2024 https://www.gov.uk/guidance/breast-screening-programme-overview Cited for: NHS breast screening invitation age range (50-71), three-year interval, organisation of double-reading mammography.
  3. meta analysis Houssami N, Bernardi D, Pellegrini M, et al. Breast cancer detection using single-reading of breast tomosynthesis (3D-mammography) compared to double-reading of 2D-mammography: evidence from a population-based trial (STORM-2). European Journal of Cancer. 2017 ;76:111–117 doi:10.1016/j.ejca.2017.02.010 Cited for: Tomosynthesis improves cancer detection and reduces recall rate vs 2D mammography; corroboration of Skaane 2013 findings.
  4. guidance Royal College of Radiologists. Guidance on screening and symptomatic breast imaging. 4th edition. London: RCR. 2019 https://www.rcr.ac.uk Cited for: UK practice for adding tomosynthesis selectively in symptomatic clinics, particularly in dense breasts; equivalent patient experience to 2D mammography.