Mammography Quality Control and MQSA Physics Testing: A Medical Physicist's Guide

Introduction

Mammography quality control (QC) under the Mammography Quality Standards Act (MQSA) is a layered, legally required program: routine tests run by technologists from daily to annually, plus a comprehensive annual survey performed by a qualified medical physicist. Together these confirm that every mammography unit produces adequate image quality at an acceptable radiation dose, and that the facility stays accredited and FDA-certified. Without a passing annual physics survey and current accreditation, a facility cannot legally perform mammography in the United States. ^{1, 2}

Mammography is the most tightly regulated imaging modality in the country. Unlike general radiography or CT, where state and FDA equipment rules set a performance floor, mammography is governed by MQSA, a federal law with its own implementing regulation at 21 CFR Part 900 that the FDA enforces through annual inspections, accreditation bodies, and certification. ¹ The reason is clinical: screening mammography looks for subtle, low-contrast findings, microcalcifications, small masses, architectural distortion, in a dense, superimposed organ, often at the limit of what the imaging system can resolve. A small drift in dose, contrast, sharpness, or artifact behavior can hide a cancer or trigger an unnecessary recall.

This guide explains how the mammography QC program is structured, what the medical physicist tests during the annual survey, how mean glandular dose is calculated and limited, and how the program maps onto MQSA, the ACR accreditation process, and the FDA's EQUIP initiative. DRPS performs these surveys and supports accreditation as part of its medical physics consulting and accreditation support services across Florida, Maryland, Virginia, Washington DC, California, and Nevada.

Topic Explanation

What is MQSA?

The Mammography Quality Standards Act (MQSA) is the federal law, implemented in regulation at 21 CFR Part 900, that requires every facility performing mammography in the United States to be accredited and certified, to use qualified personnel, and to meet defined equipment, QC, and image quality standards. ¹ It is administered and enforced by the FDA. A facility that is not certified cannot legally image patients, and certification depends on a current accreditation from an FDA-approved accreditation body, most commonly the American College of Radiology (ACR).

MQSA sets requirements in several areas that work together:

• Personnel — minimum qualifications for interpreting physicians, radiologic technologists, and the medical physicist.
• Equipment — performance standards for the mammography unit, image receptor, AEC, and display.
• Quality assurance and QC — routine technologist tests and the annual medical physicist survey.
• Medical records and reporting — including communication of results to patients.
• Accreditation and certification — the external review that confirms the facility meets the standards.

For the broader accreditation picture across modalities, see our companion guide on ACR accreditation physics requirements.

What is mammography quality control?

Mammography QC is the structured set of measurements and reviews that confirm a unit's image quality and dose remain within established limits over time, with defined action levels and corrective steps when a test fails. It is not a single annual event. It is a continuous program with two tiers:

• Routine (technologist) QC — frequent tests, from daily to annually, run by the lead or QC technologist to catch day-to-day drift before it affects patients. Examples include phantom imaging, artifact checks, compression, and display monitor evaluation.
• The annual medical physicist survey — a comprehensive evaluation of the full imaging chain (dose, AEC, kVp, HVL, image quality, artifacts, and display) performed by a qualified medical physicist, along with a mammography equipment evaluation (MEE) whenever a unit is installed, relocated, or significantly serviced. ^{2, 3}

Modern digital systems follow a QC manual specific to the unit: most facilities use the ACR Digital Mammography QC Manual or the manufacturer's QC manual that the FDA has accepted as an alternative standard. ^{2, 4} The tests, frequencies, and action limits in this guide follow the structure of those manuals; the exact tolerance for a given test is defined by the manual the unit operates under, and the physicist must use the correct one.

Digital mammography, DBT, and the standard phantom

Nearly all mammography in the United States is now full-field digital mammography (FFDM), and a large and growing share of units also offer digital breast tomosynthesis (DBT), which acquires a limited-angle series of projections and reconstructs thin slices to reduce the masking effect of overlapping tissue. DBT units carry their own QC tasks layered on top of the 2D requirements. ^{5, 6}

Image quality is anchored to a standardized phantom. The ACR accreditation phantom simulates a 4.2 cm compressed breast of roughly 50% adipose and 50% glandular tissue and contains embedded test objects, fibers, speck (microcalcification) groups, and masses, used both for accreditation scoring and for routine QC. ^{2, 3}

Key Technical Principles

The annual medical physicist survey test set

The annual survey is the physicist's core MQSA responsibility. The table below summarizes the major tests, what each one verifies, and the general nature of the tolerance or action level. The specific numeric limits are defined by the QC manual the unit operates under (ACR Digital Mammography QC Manual or the accepted manufacturer's manual), so they are described here in general terms rather than as universal thresholds.

Test	What it checks	Tolerance / action level
Mean glandular dose (MGD)	Radiation dose to the standard phantom per CC exposure	≤ 3.0 mGy (0.3 rad) per exposure for the standard ACR phantom under MQSA 1
Phantom image quality	Detection of fibers, specks, and masses in the ACR phantom	Minimum object scores per the unit's QC manual; ACR accreditation historically requires the four largest fibers, three largest speck groups, and three largest masses on the historical ACR phantom 3
Signal-to-noise / contrast-to-noise ratio (SNR/CNR)	Detector response and low-contrast performance	Within the baseline range and percentage tolerance set by the QC manual
Automatic exposure control (AEC)	Consistent detector signal across phantom thicknesses	Signal/AEC output held within the manual's tolerance across the thickness range 2
kVp accuracy and reproducibility	Tube voltage is correct and stable	Accuracy and reproducibility within the manual's stated percentage (commonly expressed as a small percent of nominal)
Half-value layer (HVL)	Beam quality / adequate filtration	HVL at or above the minimum for the kVp and target/filter, consistent with FDA 21 CFR 1020.30 7
Artifact evaluation	Detector, grid, or processing artifacts	No clinically significant artifacts; investigate and correct any found 2
Collimation / beam–image receptor alignment	Beam covers the receptor and aligns at the chest wall	Within the alignment tolerance of the QC manual and 21 CFR 1020.30 7
Compression force	Adequate, safe compression	Within the required force range (a powered-drive maximum near 200 N / ~45 lbf is commonly referenced)
Display monitor (review workstation)	Luminance, uniformity, and grayscale calibration	Luminance and DICOM GSDF calibration within the manual's limits 8
DBT-specific tests (if applicable)	Reconstructed-slice quality, z-resolution, artifact spread, DBT dose	Per the DBT unit's QC manual; baseline-relative limits are common 5, 6

The display-monitor portion overlaps conceptually with general diagnostic display QC; for the underlying calibration pattern logic, see our note on the SMPTE pattern for monitor QC.

Worked example: mean glandular dose

Mean glandular dose is not measured directly inside the breast. Instead, the physicist measures the incident (entrance) air kerma at the phantom surface for the exposure factors the unit selects for the standard phantom, then converts it to glandular dose using published conversion coefficients that depend on beam quality, breast (phantom) thickness, and glandularity. Based on articles retrieved from PubMed, the conversion-coefficient framework most widely used internationally is the Dance formulation, refined across several papers. ^{9, 10, 11}

A convenient general form is:

$$\mathrm{MGD}=K\cdot g\cdot c\cdot s$$

where:

• $K$ is the incident air kerma at the upper surface of the breast (or standard phantom), with no backscatter, for the clinical exposure;
• $g$ is the conversion factor from incident air kerma to MGD for a standard-glandularity breast, indexed by HVL and compressed thickness;
• $c$ corrects for breast composition (glandularity) differing from the reference; and
• $s$ corrects for the target/filter spectrum relative to the reference spectrum. ^{9, 10, 11}

As a simplified illustration, suppose the unit's standard-phantom exposure yields an incident air kerma of $K=6.0\mathrm{mGy}$, and the appropriate coefficients for that beam quality and the 4.2 cm, ~50% glandular standard phantom are $g=0.40$, $c=1.00$ (already at reference glandularity), and $s=1.00$:

$$\mathrm{MGD}=6.0\mathrm{mGy}\times 0.40\times 1.00\times 1.00=2.4\mathrm{mGy}$$

That result, $2.4\mathrm{mGy}$, sits below the MQSA limit of $3.0\mathrm{mGy}$ per CC view of the standard phantom, so it would pass on dose. ¹ The numbers above are illustrative; in practice the physicist reads $K$ from a calibrated dosimeter at the unit's actual clinical technique and looks up $g$, $c$, and $s$ from the conversion tables matched to the measured HVL, target/filter, and thickness.

Worked example: AEC and kVp reproducibility

Reproducibility tests confirm that the unit delivers consistent output when nothing about the setup changes. A common metric is the coefficient of variation (CV) across repeated exposures, or the normalized range:

$$\mathrm{Reproducibility}=\frac{X_{\max }-X_{\min }}{X_{\max }+X_{\min }}$$

For kVp, mAs, AEC signal, or air kerma, a typical acceptance is that this value stays at or below 0.05 (i.e., within ±5% of the mean). For example, five repeated kVp readings of 28.4, 28.2, 28.5, 28.3, and 28.4 give:

$$\frac{28.5-28.2}{28.5+28.2}=\frac{0.3}{56.7}\approx 0.005$$

which is comfortably within a ±5% reproducibility window.

Clinical Impact

Why dose and image quality must be balanced, not just minimized

Mammography QC is fundamentally a balancing act: enough dose and contrast to detect early cancers, but no more dose than necessary. Driving dose too low degrades the contrast-to-noise ratio and can hide microcalcifications or low-contrast masses; allowing dose to creep up adds risk without diagnostic benefit. The annual survey checks both ends of that balance, the MGD ceiling and the image-quality floor, because passing one without the other does not protect patients. ^{1, 2}

This is why the standard phantom scoring matters. A unit that meets the dose limit but no longer resolves the smallest required fibers, specks, and masses is failing at its actual job, finding subtle disease. Conversely, a unit producing beautiful phantom images at an excessive MGD is exposing every screened patient to avoidable dose. The physicist's report ties these together and gives the facility defensible, documented evidence for both. ³

What happens when QC catches a problem

Routine QC and the annual survey are early-warning systems. A drifting AEC, a rising MGD, a new detector artifact, or a slow loss of phantom score often shows up in QC before a radiologist notices it on clinical images. Detector-based studies of automated phantom QC have shown that systematic analysis can track unit performance over time and flag degradation in a multi-unit center. Based on articles retrieved from PubMed, automated daily phantom QC has been demonstrated to monitor multiple mammography systems in a centralized, repeatable way. ¹² When QC catches a failure, the unit is taken out of clinical service for that issue until it is corrected and re-verified, which is exactly the point: the program prevents bad images from reaching patients rather than discovering problems after the fact.

DBT changes the picture, literally and for QC

Digital breast tomosynthesis reduces tissue superimposition and can improve cancer detection and reduce recall rates, but it adds acquisition modes, reconstruction algorithms, and dose considerations that 2D QC alone does not cover. Based on articles retrieved from PubMed, the harmonized QC program for the large TMIST tomosynthesis trial defined tomosynthesis-specific weekly tests, signal-difference-to-noise ratio of a low-contrast mass, artifact spread, spatial resolution, and noise power spectra, and reported standard-phantom mean glandular doses for single tomosynthesis exposures in the range of roughly 1.2–1.7 mGy across systems (5th–95th percentile). ¹³ The practical lesson for any DBT site is that QC limits are often best evaluated as deviations from a unit-specific baseline, because reconstruction algorithms differ enough between vendors that a single universal threshold is not appropriate. ¹³

Practical Optimization Tips

A defensible mammography QC program runs on the same disciplined cadence year after year. The following practices keep a program audit-ready and clinically sound.

1. Use the correct QC manual, and only one per unit

Each unit operates under a single QC manual, the ACR Digital Mammography QC Manual or the FDA-accepted manufacturer's manual. Mixing tests or tolerances from different manuals on the same unit is a common finding. Confirm which manual applies before running or interpreting any test. ^{2, 4}

2. Keep the technologist QC current and documented

The annual physics survey is only one layer. Daily and weekly technologist tasks, phantom imaging, artifact checks, and review-workstation checks, catch most real-world drift. Logs should be complete, signed, and reviewed; gaps in routine QC are among the most frequent inspection observations.

3. Track trends, not just pass/fail

Single passing values can mask a slow slide toward an action limit. Plotting MGD, SNR/CNR, AEC output, and phantom scores over time reveals degradation early, often before a hard failure. This is the core idea behind automated and centralized QC monitoring. ^{12, 13}

4. Treat the review workstation as part of the imaging chain

A perfectly calibrated acquisition unit feeding an uncalibrated or aging interpretation monitor still produces missed findings. Display luminance, uniformity, and DICOM grayscale calibration belong in the QC program. ⁸

5. Plan ahead for the MEE

A mammography equipment evaluation is required before a new, relocated, or significantly serviced unit returns to clinical use. Scheduling the physicist promptly avoids downtime, because the unit cannot image patients until the MEE confirms it meets standards. ^{2, 3}

Common pitfalls to avoid

• Letting MGD creep. A unit that drifts upward in dose can still pass clinically while exposing every patient to avoidable dose. Trend it.
• Skipping artifact evaluation. Detector and grid artifacts can mimic or obscure pathology and are easy to miss without a deliberate check.
• Ignoring the display side. Review-workstation QC is part of the program, not an optional extra.
• Assuming DBT is covered by 2D QC. Tomosynthesis adds its own tests; running only 2D QC leaves the reconstruction unmonitored.
• Weak corrective-action documentation. EQUIP inspections focus on whether the facility actually acts on QC findings, not just whether tests were run.

Regulatory Considerations

Mammography is regulated differently from the rest of diagnostic imaging: it is governed by MQSA (21 CFR Part 900), a federal statute enforced directly by the FDA, in addition to the general X-ray equipment performance standard at 21 CFR 1020.30 and applicable state rules. ^{1, 7} A facility must be accredited by an FDA-approved body and certified by the FDA (or an FDA-approved state certifying agency) to legally perform mammography.

Key frameworks to reference:

• MQSA, 21 CFR Part 900 — the federal regulation setting accreditation, certification, personnel, equipment, QC, recordkeeping, and the mean glandular dose limit; enforced by the FDA. ¹
• FDA 21 CFR 1020.30 — the federal performance standard for diagnostic X-ray systems, including beam quality (HVL), collimation, and reproducibility requirements that the mammography survey also touches. ⁷
• ACR Mammography Accreditation Program — the most widely used FDA-approved accreditation route, which reviews clinical and phantom images, dose, and QC documentation. ³
• ACR Digital Mammography QC Manual — the QC program most facilities operate under, defining the tests, frequencies, and action limits for technologists and the physicist. ²
• ACR–AAPM Technical Standard for Diagnostic Medical Physics Performance Monitoring of Mammography Equipment — the professional standard describing the qualified medical physicist's role and the scope of the survey. ¹⁴
• FDA EQUIP — Enhancing Quality Using the Inspection Program, the FDA inspection emphasis on whether facilities have, and act on, effective QC and image-quality review processes. ¹⁵

Jurisdiction note. Mammography units are X-ray machines, so they fall under FDA and state radiation-control authority rather than the NRC. MQSA layers a federal certification scheme on top of that. Of the states DRPS serves, Florida, Maryland, Virginia, California, and Nevada administer their own radiation-control programs, while Washington, DC is within the NRC's direct regulatory authority for byproduct material; in all of them, mammography certification flows through MQSA and an FDA-approved accreditation body. A facility should confirm both its MQSA certification status and its state X-ray registration. For how occupational dose monitoring fits the broader safety program, see occupational exposure monitoring; for imaging pregnant or potentially pregnant patients, see fetal dose in medical imaging.

The annual survey, MEE reports, and routine QC logs should be retained and presented as a coherent package. Under EQUIP, the inspector wants evidence that the facility not only runs the tests but reviews image quality and takes corrective action when something fails. ¹⁵ DRPS aligns the survey, documentation, and accreditation submission as part of medical physics consulting and accreditation support.

Frequently Asked Questions (FAQs)

What is mammography quality control under MQSA?

Mammography QC under MQSA is the required, layered program of routine technologist tests and an annual medical physicist survey that confirms each mammography unit produces adequate image quality at an acceptable radiation dose. The Mammography Quality Standards Act is enforced by the FDA, and a facility must remain accredited and certified to legally perform mammography.

What does the annual medical physicist mammography survey include?

The annual survey evaluates the full imaging chain: mean glandular dose, automatic exposure control performance, kVp accuracy and reproducibility, half-value layer, phantom image quality, signal-to-noise and contrast-to-noise ratios, artifact evaluation, collimation, compression force, and display monitor performance. The exact test set follows the unit's QC manual, typically the ACR Digital Mammography QC Manual or the manufacturer's manual.

What is the mean glandular dose limit in mammography?

Under MQSA, the mean glandular dose for a single craniocaudal view of the standard ACR accreditation phantom (simulating a 4.2 cm compressed breast of 50% glandular tissue) must not exceed 3.0 mGy (0.3 rad) per exposure. A unit exceeding this limit cannot be used for clinical imaging until corrected.

What is the difference between technologist QC and the physicist survey?

Technologists perform frequent routine QC (daily to annually) to catch day-to-day drift, such as phantom imaging, artifacts, and monitor checks. The medical physicist performs a comprehensive annual survey, plus a mammography equipment evaluation (MEE) on new or modified units, that verifies the unit meets MQSA performance standards before and during clinical use.

Does digital breast tomosynthesis require separate QC?

Yes. Digital breast tomosynthesis (DBT) systems are tested under the QC manual specific to that unit, which adds tomosynthesis tasks such as reconstructed-slice image quality, z-axis resolution, artifact spread, and dose for the tomosynthesis acquisition. DBT does not remove the standard 2D mammography QC requirements.

What is the FDA EQUIP initiative?

EQUIP (Enhancing Quality Using the Inspection Program) is an FDA initiative under MQSA in which inspectors ask facilities to demonstrate that they have effective QC procedures, that images are reviewed for quality, and that corrective action is taken when problems are found. It emphasizes ongoing clinical image quality, not just the pass/fail of phantom tests.

Who can perform mammography QC physics testing?

The annual survey and equipment evaluations must be performed by a qualified medical physicist who meets the MQSA personnel requirements, including board certification or equivalent qualifications, mammography-specific training, and continuing education. Many facilities contract this work to an independent consulting medical physicist.

Key Takeaways

• Mammography QC is a layered, legally required program. Routine technologist tests (daily to annually) plus an annual medical physicist survey keep each unit accredited and FDA-certified under MQSA.
• The MGD limit is firm. Mean glandular dose for a single CC view of the standard ACR phantom must not exceed 3.0 mGy (0.3 rad); a unit over the limit cannot image patients until corrected.
• Dose and image quality are balanced, not just minimized. The survey verifies both a dose ceiling and an image-quality floor, because passing one without the other does not protect patients.
• Use the correct QC manual. Each unit runs under one manual (ACR Digital Mammography QC Manual or an accepted manufacturer's manual), which defines the specific tolerances and frequencies.
• DBT needs its own QC. Tomosynthesis adds reconstructed-slice, z-resolution, artifact-spread, and dose tests, and limits are often best judged against a unit-specific baseline.
• EQUIP focuses on action. FDA inspections increasingly check that the facility reviews image quality and acts on QC findings, not just that tests were performed.

Conclusion

Mammography QC is the most prescriptive QC program in diagnostic imaging, and for good reason: the modality hunts for subtle, early disease in a difficult organ, and the cost of a missed cancer or an unnecessary recall is high. MQSA turns that clinical stake into a federal requirement, with an annual medical physicist survey, routine technologist QC, a hard mean glandular dose limit, accreditation, and FDA certification all working together.

A strong program does more than pass an annual phantom test. It trends dose and image quality over time, keeps technologist QC complete and reviewed, treats the review workstation and any DBT capability as part of the imaging chain, and documents corrective action so the facility can demonstrate quality under EQUIP. The medical physicist's survey is the backbone of that program: it verifies the physics, anchors the documentation, and gives the facility defensible evidence that every patient is imaged safely and well.

How DRPS Can Help

Diagnostic Radiation Physics Services performs the annual MQSA medical physicist survey and mammography equipment evaluations, reviews technologist QC programs, evaluates dose and image quality, and prepares facilities for ACR accreditation and FDA inspection. This work fits within medical physics consulting, accreditation support, and broader CT and diagnostic physics testing for multi-modality imaging centers.

DRPS supports facilities across our service locations, including Florida, Maryland, Virginia, Washington DC, California, Nevada, New York, Pennsylvania, New Jersey, and Delaware. If you are starting a new mammography service, adding a DBT unit, or preparing for accreditation or an EQUIP inspection, contact DRPS to schedule a survey.

A well-run mammography QC program makes the safe, high-quality image the routine result, not the lucky one.

Related Resources

• ACR accreditation physics requirements
• SMPTE pattern for monitor QC
• Occupational exposure monitoring
• Fetal dose in medical imaging
• Accreditation support
• Medical physicist consulting
• CT physics testing

References

1. U.S. Food and Drug Administration. Mammography Quality Standards Act (MQSA); 21 CFR Part 900. ecfr.gov
2. American College of Radiology. Digital Mammography Quality Control Manual. American College of Radiology. acr.org
3. American College of Radiology. Mammography Accreditation Program Requirements. acr.org
4. U.S. Food and Drug Administration. Alternative Standards and Approved Mammography QC Manuals under MQSA. fda.gov
5. American Association of Physicists in Medicine. AAPM mammography and breast tomosynthesis quality control guidance and task group resources. aapm.org
6. U.S. Food and Drug Administration. Digital Accreditation and Digital Breast Tomosynthesis under MQSA. fda.gov
7. U.S. Food and Drug Administration. 21 CFR 1020.30: Diagnostic X-ray Systems and Their Major Components. ecfr.gov
8. American Association of Physicists in Medicine. AAPM TG-18: Assessment of Display Performance for Medical Imaging Systems. aapm.org
9. Dance DR, Skinner CL, Carlsson GA. Breast dosimetry. Appl Radiat Isot. 1999;50(1):185-203. doi:10.1016/s0969-8043(98)00047-5. PubMed
10. Dance DR, Skinner CL, Young KC, Beckett JR, Kotre CJ. Additional factors for the estimation of mean glandular breast dose using the UK mammography dosimetry protocol. Phys Med Biol. 2000;45(11):3225-3240. doi:10.1088/0031-9155/45/11/308. PubMed
11. Dance DR, Young KC. Estimation of mean glandular dose for contrast enhanced digital mammography: factors for use with the UK, European and IAEA breast dosimetry protocols. Phys Med Biol. 2014;59(9):2127-2137. doi:10.1088/0031-9155/59/9/2127. PubMed
12. Sundell VM, Mäkelä T, Meaney A, Kaasalainen T, Savolainen S. Automated daily quality control analysis for mammography in a multi-unit imaging center. Acta Radiol. 2019;60(2):140-148. doi:10.1177/0284185118776502. PubMed
13. Maki AK, Mawdsley GE, Mainprize JG, et al. Quality control for digital tomosynthesis in the ECOG-ACRIN EA1151 TMIST trial. Med Phys. 2023;50(12):7441-7461. doi:10.1002/mp.16786. PubMed
14. American College of Radiology and American Association of Physicists in Medicine. ACR–AAPM Technical Standard for Diagnostic Medical Physics Performance Monitoring of Mammography Equipment. acr.org
15. U.S. Food and Drug Administration. Enhancing Quality Using the Inspection Program (EQUIP). fda.gov