STANDARDS ACT
The MQSA, a federal law regarding mammography enforced by the FDA, stipulates that all institutions performing mammogra- phy must be certified by the FDA. A prerequisite to FDA certi- fication is accreditation to perform mammography by an FDA- approved accrediting body, such as the ACR or an FDA-approved state accrediting body. Arkansas, Iowa, and Texas are approved to accredit mammography facilities in their own states. The
MQSA final regulations are listed in the Federal Register. To update facilities on the latest regulation changes and updates, the FDA maintains an MQSA website (http://www.fda.gov), which includes a section to guide users who have questions on MQSA compliance.
The MQSA certification involves an initial application to the FDA and FDA approval to perform mammography, continuous documentation of compliance, and annual facility inspection by an MQSA or state inspector. Noncompliance with regulations may result in FDA citations, with time limits on deficiency correc- tions. Serious noncompliance issues may result in facility closure.
Falsification of data submitted to the FDA can result in monetary fines and jail terms.
The MQSA equipment requirements for mammography are summarized in Box 1.8, and the MQSA qualification requirements for radiologists, technologists, and medical physicists are outlined in Boxes 1.9 to 1.11.
One radiologist at each facility must be designated as the Lead Interpreting Physician to oversee the facility’s quality assurance (QA) program (Boxes 1.12 and 1.13). The Audit Interpreting Physician oversees assessment of mammography outcomes to evaluate the accuracy of interpretation. The facility must have a method for recording outcomes on interpretation of all abnor- mal mammographic findings and tallying these interpretations for each individual physician and for the group as a whole, pro- viding feedback to each radiologist on a yearly basis (Box 1.14). A portion of the medical audit includes review of the pathology in cases recommended for biopsy.
One radiologic technologist, designated as the QC technologist, oversees the quality control (QC) tasks outlined in Table 1.4,
A B C
D
E
FIG. 1.22 Image-processing artifacts unique to screen-film mammography. (A) Magnified view of a minus-den- sity (white) fingerprint artifact (arrow), usually caused by contact with the film before exposure. (B) Magnified view of a plus-density (dark) fingerprint artifact (arrow), usually caused by contact with the film after exposure but before processing. (C) Subtle plus-density tree static artifacts (arrow) caused by static discharge in a limited region of the film. The light emitted from the static discharge causes localized film exposure before processing.
(D and E) Guide shoe marks. Dark lines (D, arrowheads) at the edge of the film in the direction of film travel that are evenly spaced are caused by excessive pressure on the film emulsion from guide shoes as the film travels through the processor. Guide shoe marks can sometimes result in minus-density linear artifacts in the direction of film travel as well. A film guide turns the film as it passes through the processor. Such guides (E, arrowheads) are located at the top and bottom of each tank. Improperly adjusted film guides can lead to excessive pressure on the film emulsion and result in guide shoe artifacts.
A Motion B No motion
FIG. 1.23 Motion artifact on digital mammography. (A) Right mediolateral oblique (RMLO) view shows blurred breast tissue most evident in lower breast (circle). (B) On a corrected RMLO, the breast tissue and Cooper’s liga- ments appears more distinct against a fatty background. Longer exposure times can lead to patient motion.
A B
FIG. 1.24 Hexagonal grid lines on digital mammography. Grid lines on a right craniocaudal (RCC) view (A) disap- peared in a corrected RCC view (B). This artifact may be attributed to the stopping or slowing down of grid oscil- lation in the Bucky, causing the grid lines to be superimposed on the image. To correct this artifact, the technolo- gist should repeat the exposure and, if the artifact persists, a call should be made for servicing the equipment.
A B
FIG. 1.25 Edge of small breast paddle. A unilateral vertical linear artifact (arrows) is seen outside the right breast on a tomosynthesis slice (A) as a tomosynthesis-synthesized 2D image (B). These vertical linear artifacts are the edge of the small breast paddle used to compress small breasts. Usually, the paddle edge is not included on the images.
A
2D Tomo-synthesized 2D Tomo slice
B C
FIG. 1.26 Shadow artifacts on tomosynthesis. (A) Conventional digital 2D. (B) Tomosynthesis-synthesized 2D.
(C) Tomosynthesis slice. There are two small metal BBs and an external skin marker (A). Tomosynthesis im- ages (B and C) show artifactual black lines (arrows) above and below high-attenuation objects such as met- al markers or macrocalcifications caused by the tomosynthesis reconstruction. The shadow artifacts shown in this image are a result of reconstruction of limited angle projections. They occur on relatively small-size ex- tremely bright objects such as clips, pins, BBs, large calcifications, etc. Software is being developed to reduce these artifacts.
FIG. 1.27 Out-of-plane artifacts on tomosynthesis. Tomosynthe- sis-synthesized two-dimensional (2D) image shows multiple lines (arrows) under the linear scar marker that were caused by ghost artifacts from the metallic marker in out-of-focus planes.
BOX 1.8 Mammography Quality Standards Act Equipment Requirements for Mammography Be specifically designed for mammography
Have a breast compression device and have additional hand- operated compression to augment motor-driven compression Have image receptors, moving grids, and compression paddles
for both 18 × 24-cm and 24 × 30-cm image receptors (screen- film only)
The mean glandular dose to a 4.5-cm thick breast is less than 3 mGy (0.3 rad) when the site’s clinical technique is used Can angulate 180 degrees from craniocaudal orientation in at
least one direction
X-ray system must have a functioning postexposure display of the actual x-ray focal spot and the target material used during each exposure.
Other minimum standards for beam limitation and light field, magnification capability, automatic exposure control, and, for screen-film mammography, requirements for x-ray film, in- tensifying screens, film processing solutions, lighting and hot lights, film masking devices
Modified from the Federal Register. Available at http://www.fda.gov
BOX 1.9 Mammography Quality Standards Act Qualifications for Interpreting Physicians
Be licensed to practice medicine in a state, and
Be certified by a body approved by the Food and Drug Administration to certify interpreting physicians or have 3 months’ full-time training in mammography interpretation, radiation physics, radiation effects, and radiation protection, and
Have earned 60 hours of documented mammography continuing medical education (CME) (time in residency will be accepted if documented in writing) and 8 hours of training in each modal- ity (such as screen-film or digital mammography),
and
Have read at least 240 examinations in the preceding 6 months under supervision or have read mammograms under the su- pervision of a fully qualified interpreting physician (see the Federal Register for exact requirements),
and
Have read 960 mammograms over a period of 24 months, and
Have earned at least 15 Category 1 CME credits in mammography over a 36-month period, with 6 credits in each modality used, and
To perform a new imaging modality (eg, digital mammography, digital breast tomosynthesis), the interpreting physician must have 8 CME credits specific to that modality before starting the modality.
To reestablish qualifications, either interpret or double read 240 mammograms under direct supervision or bring the total to 960 over a period of 24 months and accomplish these tasks within the 6 months immediately before resuming indepen- dent interpretation. Regarding CME, if the requirement of 15 hours per 36 months is not met, the total number of CME hours must be brought up to 15 per 36 months before resum- ing independent interpretation.
Modified from the Federal Register. Available at http://www.fda.gov
BOX 1.10 Mammography Quality Standards Act Qualifications for Radiologic Technologists
Have a license to perform radiographic procedures in their state or be certified by one of the bodies (such as the American Registry of Radiologic Technologists) approved by the Food and Drug Administration,
and
Have undergone 40 hours of documented mammography train- ing, with 8 hours of instruction in each modality used, and have completed at least 25 mammography examinations, and
Complete 200 examinations in the previous 24 months and com- plete (or teach) at least 15 continuing education units (CEUs) in the past 36 months, including 6 in each modality used.
Modified from the Federal Register. Available at http://www.fda.gov
Note: To reestablish qualifications, must complete 25 examinations under direct supervision and complete 15 CEUs per 36 months.
BOX 1.11 Mammography Quality Standards Act Qualifications for Medical Physicists
Have a license or approval by a state to conduct evaluations of mammography equipment under the Public Health Services Act or have certification in an accepted area by one of the accredit- ing bodies approved by the Food and Drug Administration, and
Have at least a master’s degree or higher in a physical science with at least 20 semester hours (30 quarter hours) of graduate or undergraduate physics,
and
Have at least 20 contact hours of mammography facility survey training,
and
Have the experience of conducting surveys of at least 1 mammog- raphy facility and at least 10 mammography units,
and
Before independently performing surveys or mammography equipment evaluations on any new mammographic modality, have at least 8 hours of training in the modality,
and
Have conducted a minimum of two mammography facility sur- veys and a total of six mammography unit surveys during the 24 months immediately preceding the date of the facility’s an- nual MQSA inspection,
and
Have taught or completed at least 15 continuing education units (CEUs) in medical physics or mammography during the 36 months immediately preceding the date of the facility’s annual MQSA inspection.
Modified from the Federal Register. Available at http://www.fda.gov
BOX 1.12 Quality Assurance Program for Equipment
All facilities must establish and maintain a quality assurance (QA) program with written designation of a lead inter- preting physician, medical physicist, and quality control technologist.
For screen-film systems, the QA program is the same as described in Hendrick et al. (1999); for digital and digital breast tomosyn- thesis units, a QA program as described by the image receptor manufacturer’s QC manual.
Maintenance of log books documenting compliance and correc- tive actions for each unit.
Establish and maintain radiographic images of phantoms to assess performance of the mammography system for each unit.
Major changes from the interim regulations include weekly phan- tom image quality testing and mammography unit perfor- mance tests after each relocation of a mobile unit.
Modified from the Federal Register. Available at http://www.fda.gov
BOX 1.13 Quality Assurance for Clinical Images Monitoring of repeat rate for repeated clinical images and their
causes
Record keeping, analysis of results, and remedial actions taken on the basis of this monitoring
Modified from the Federal Register. Available at http://www.fda.gov
BOX 1.14 Quality Assurance for Interpretation of Clinical Images
Establishment of systems for reviewing outcome data from mam- mograms, including
Disposition of all positive mammograms
Correlation of surgical biopsy results with mammogram reports Designation of a specific physician to ensure data collection and
analysis and show that the analysis is shared with the facility and individual physicians
Modified from the Federal Register. Available at http://www.fda.gov
TABLE 1.4 Technologist Quality Control Tests for Screen-Film Mammography
Periodicity Quality Control Test Desired Result Daily Darkroom cleanliness No dust artifacts Daily Processor quality
control Density difference and mid-density changes not to exceed control limits of ±0.15 Weekly Screen cleanliness No dust artifacts on films Weekly Viewbox cleanliness No marks on panels,
uniform lighting Weekly Phantom image
evaluation Film density >1.4 with control limits of ±0.20 Densities do not vary
over time or between units
Minimum test objects seen: four largest fibers, three largest speck groups, three largest masses
Monthly Visual checklist Each item on checklist present and functioning properly Quarterly Repeat analysis Overall repeat rate of <5%
Percent repeats similar for each category Quarterly Analysis of fixer
retention Residual sodium thiosulfate (hypo)
≤0.05 μg/cm3
Semiannually Darkroom fog Fog ≤0.05 optical density difference for 2-minute exposure in darkroom Semiannually Screen-film contact Large areas (>1 cm)
of poor contact unacceptable Semiannually Compression Power mode: 25–45 lb
Manual mode: >25 lb From Hendrick et al: Mammography quality control manual, Reston, VA, 1999, American College of Radiology, p. 119.
which specifies the minimum frequency of each QC test and action limits for test performance. One important test per- formed by the QC technologist and reviewed by the interpret- ing physician is acquisition and evaluation of the mammogra- phy phantom image; this test is performed at least weekly and evaluates the entire imaging system. The phantom consists of fibers, speck clusters, and masses of various sizes imbedded in a uniform phantom material. The technologist takes a phantom radiograph using the site’s clinical technique for a 4.5-cm thick compressed breast, the radiograph is processed on the site’s film
processor or produced by the digital system, and the image is evaluated for the number of objects seen in each category. To pass accreditation and meet MQSA requirements, the phantom should show a minimum of four fibers, three speck groups, and three masses (Box 1.15). The phantom image should also be free of significant artifacts. These and other tests are used to evaluate the entire imaging system.
The medical physicist surveys the equipment just after instal- lation, after important major equipment repairs or upgrades, and at least annually, performing the QC tests outlined in Box 1.16.
The medical physicist’s survey report is an important component of the QA program and is reviewed by the supervising physician to ensure high-quality mammography. The facility is responsible for correcting deficiencies pointed out by the site medical physi- cist and documenting corrective actions.
Each year, the mammography facility is inspected by state or federal inspectors who evaluate compliance with MQSA regula- tions. Site QA records and site personnel qualifications are rou- tinely checked by the MQSA inspector. Correction of deficien- cies specified in the medical physicist’s report is an important item checked by MQSA inspectors. Noncompliance with MQSA requirements may result in warnings requiring corrective actions or, in extreme cases, facility closure.
Screen-Film Mammography Quality Control For SFM, MQSA specifies the QA/QC tests to be performed by the QC technologist and the site medical physicist, as well as how frequently these tests must be performed. Technologist test frequencies range from daily to semiannually, as speci- fied in Table 1.4. Medical physicist tests are required annually, on acceptance of new equipment, or after major equipment changes and before its use on patients or volunteers (see Box 1.16). The technologist and medical physicist tests for SFM are described in detail in the 1999 edition of the ACR Mammogra- phy Quality Control Manual (Hendrick, 1999).
Full-Field Digital Mammography Quality Assurance and Quality Control
To comply with MQSA requirements, all personnel must have 8 hours of training specific to digital mammography, and that train- ing must be documented in writing before clinical use of FFDM units in that facility (Box 1.17). Specifically, the radiologist must receive 8 hours of training in interpretation of digital mammog- raphy, with the strong recommendation from the FDA that train- ing includes instruction from a radiologist experienced in digital mammography interpretation on the specific system used. Tech- nologists and medical physicists also must have documented training by appropriately qualified individuals; for example, the manufacturer’s application specialists or other qualified individu- als should train technologists, and medical physicists qualified in digital mammography should provide hands-on training for medical physicists. After meeting initial education requirements, all personnel involved in digital mammography should receive 6 hours of Category 1 continuing medical education (CME) or con- tinuing educational units (CEU) specifically in digital mammog- raphy every 3 years, which may be part of the required 15 hours of continuing education required for all personnel in mammogra- phy. The completion of the required 15 hours of Category 1 CME in mammography every 3 years must be documented in writing.
The MQSA requires that QC testing for FFDM is performed by the facility “according to the image receptor manufacturer’s specification.” Each digital manufacturer has a detailed QC man- ual specifying tests, test frequencies, and pass–fail criteria. All manufacturers’ QC manuals differ in the specific tests, frequen- cies, and criteria.
For some tests, such as mean glandular dose for the ACR phantom being less than 3 mGy, the FDA specifies that failures must be corrected immediately before that component of the FFDM system (eg, the digital mammography unit, review work- station, laser imager) can be used. Test failures that must be cor- rected immediately include phantom image quality, contrast-to- noise ratio, radiation dose, and review workstation calibration.
For other test failures, such as repeat analysis, collimation assess- ment, and other physics tests, 30 days are permitted for correc- tion after problem identification. Typical digital mammography QC tests are listed in Box 1.18, although these vary somewhat by digital manufacturer.
Digital Breast Tomosynthesis Quality Assurance and Quality Control
As with digital mammography, DBT is considered a new modal- ity. To add DBT capability to an existing mammography unit, the facility must apply to the FDA to have its certificate extended to include the DBT portion of the unit. The certification exten- sion applies only to the DBT portion of the unit. The facility must have the 2D portion of the unit accredited by one of the accredi- tation bodies already approved to accredit digital mammogra- phy systems. In addition, the MQSA requires that all personnel involved in the performance of DBT (radiologists, technologists,
BOX 1.17 Educational Requirements for New Personnel Using Digital Mammography
Eight hours of training specific to digital mammography before its use
Six hours of Category 1 continuing medical education or continu- ing education unit credits in this new modality every 3 years;
the 6 hours can be part of the required 15 hours of continuing education in mammography required by the Mammography Quality Standards Act
BOX 1.15 Phantom Image
Evaluates the entire mammographic imaging chain (other than technologist positioning)
Performed at least weekly
Must see four fibers, three speck groups, three masses Must be free of significant artifacts
From Hendrick et al: Mammography quality control manual, Reston, VA, 1999, American College of Radiology, p 119.
BOX 1.16 Medical Physicist’s Screen-Film Mammography Quality Control Tests
(Annually and after Major Equipment Changes) 1. Unit assembly evaluation
2. Assessment of collimation 3. Evaluation of system resolution
4. Automatic exposure control (AEC) assessment of performance 5. Uniformity of screen speed
6. Artifact evaluation
7. Evaluation of image quality 8. kVp accuracy and reproducibility
9. Assessment of beam quality (half-value layer measurement) 10. Breast entrance exposure, AEC reproducibility, average glan-
dular dose, and radiation output rate 11. Viewbox luminance and room luminance
From Hendrick et al: Mammography quality control manual, Reston, VA, 1999, American College of Radiology.
and medical physicists) must have 8 hours of training specific to DBT, either including or supplemented by training in the unique features of the specific manufacturer’s DBT system(s) used. New modality training must be documented in writing before clinical use of DBT in that facility. After meeting initial DBT educational requirements, all personnel involved in DBT should receive 6 hours of Category 1 CME or CEU in DBT every 3 years, which may be part of the required 15 hours of continuing education every 3 years required for all personnel in mammography.
The MQSA requires that QC testing for DBT, like digital mam- mography, is performed by the facility according to the DBT manufacturer’s specifications. Each DBT manufacturer has a QC manual specifying DBT QC tests, test frequencies, and pass–fail criteria. Most tests are identical to those performed for 2D digital mammography, but may include additional tests unique to DBT.
Both 2D and DBT-specific QC tests should be performed on the equipment used for DBT. A list of QC tests appropriate for a DBT system is given in Box 1.19, although these differ somewhat by manufacturer. These tests should be performed in addition to conventional FFDM QC tests with any DBT-specific hardware or software installed.