The Digital Mammographic Imaging Screening Trial (DMIST) established the benefits of digital mammography over film-screen, indicating that 65% of women -- those younger than 50, who are pre- or perimenopausal, who have dense breasts -- would benefit from the digital technology. But even so, the process of transitioning to digital can be challenging for facilities on many levels: financially, operationally, and legally.
At the 2007 American Healthcare Radiology Administrators (AHRA) meeting in Orlando, FL, Bonnie Rush, president of Breast Imaging Specialists (BIS) of San Diego, gave attendees an overview of the legal and regulatory issues that arise from the process of converting to digital mammography.
The digital divide
What happens if a facility is "living in the digital divide" -- offering both digital and analog mammography? There are patient issues, legal issues, and productivity issues in this situation, Rush said. If a facility has digital units to which it could refer a woman in the particular patient subset identified by DMIST, it's better to do so; otherwise, the facility opens itself up to accusations of delayed diagnosis if an analog exam doesn't find cancers that a digital one finds later.
The key question, Rush said, is how a facility in the digital divide triages its patients.
Some centers have installed one digital unit and tried offering digital mammography on a first-come, first-served basis, performing annual digital follow-ups if a patient's prior studies were done digitally. But as more and more women ask for the technology, accommodating those requests can become challenging. Other centers have their radiologists look at each woman's previous year's films to determine whether she would benefit from digital imaging.
But prescreening each patient is time-consuming, and the facility becomes open to the potential of legal risk if cancer is found the next year on a digital scan after the previous year's analog mammogram. And toggling back and forth between analog and digital decreases radiologists' overall productivity, Rush said. Often these factors can tip a facility over the divide -- to digital.
"If you can afford it, make the jump all at once," Rush said.
Accreditation and certification
Once a facility decides to go digital, it enters into a complex process. Only Mammography Quality Standards Act (MQSA)-certified facilities can lawfully provide mammography services, Rush said. A facility is issued an MQSA certificate after the accrediting body (AB) notifies the certifying agency (CA) that the facility's accreditation application is acceptable. The AB accredits the facility once it meets the quality standards under MQSA, which is established through a review of the facility's equipment, personnel, and practices (including clinical images, phantoms, and dose).
The accreditation process includes the following steps:
- A medical equipment evaluation (MEE) by a medical physicist (MP).
- Application is sent to the AB with fees.
- The AB notifies the CA within two business days of acceptance of application.
- Facility receives six-month certificate.
A facility must have its MQSA certificate before beginning patient exams, Rush said. What about adding a new digital mammography unit to the workload? The Centers for Medicare and Medicaid (CMS) will not reimburse a facility for exams performed until the certifying agency has been notified by the accrediting body that they've received the application materials for the new device. File those, wait three business days, contact the accrediting body to confirm that the certifying agency received the information, then proceed with patient exams, Rush advised.
After filing its application, the facility will receive an accreditation packet, which requires it to submit hard-copy clinical and phantom images and TLD (dosimeter) within 45 days. After a 60-day wait, it will receive a three-year accreditation and certification.
Submission considerations for images to be aware of include:
- For digital, the American College of Radiology (ACR) accepts only hard-copy images for accreditation.
- For phantom images, do not zoom or rotate, and print as close to true size as possible.
- Clinical images must be of final interpretation quality, entire breast must fit on the image, no tiling, print as close to true size as possible, and they must contain patient ID information.
- Lead interpreting physician must review and approve all hard-copy images.
Who accredits? The ACR, and the states of Arkansas, Iowa, and Texas.
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Who certifies? The U.S. Food and Drug Administration (FDA), Illinois, Iowa, and South Carolina. A facility must use the state certifying agency, Rush said; their requirements are the same as the FDA's.
Computed radiography (CR) accreditation and certification are specific to the mammography unit, according to Rush: If a facility has multiple film-screen units and plans to use CR with more than one, it must submit applications for each unit, even if they are the same make and model.
The medical physicist's job
A facility's medical physicist performs an initial survey upon installation of the digital device, the mammography equipment evaluation (MEE), as well as annual surveys and software upgrades. MPs need to have met the eight-hour, new modality training requirement, but should also be trained on any unique features to the equipment before performing evaluations on other units. Facilities should document the full-field digital mammography (FFDM) training their MPs receive, Rush said. MEE and annual survey forms are available from the ACR. Annual surveys must be performed once per year (up to 14 months in between surveys is acceptable) and signed by the MP that performed or supervised the survey. As of July, annual surveys no longer need to be sent to the AB each year, she said.
Keep in mind that the quality control tests vary from vendor to vendor: For example, for the flat field test, GE Healthcare's and Fischer Medical Technologies' manuals call it "flat field," but Lorad/Hologic calls it "artifact evaluation" and Siemens Medical Solutions calls it "detector calibration."
Software changes and upgrades are considered major repairs, and the equipment manufacturer will list the tests and who must perform them: some must be done by the MP or under direct supervision of the MP, while some can be performed by the QC technologist under MP oversight.
Personnel training requirements
A facility's personnel need to have initial modality-specific training and continuing education, Rush said. Modality-specific training should be at least eight hours (those staff members who used FFDM prior to January 1, 2006, are considered to have met this requirement). For CR or DR, personnel should be trained on component differences before they use the equipment clinically -- positioning applications training is especially helpful for DR, since it has only one receptor size, Rush said.
"Every technologist pines for positioning classes," Rush said. "You can never offer too many."
All this training must be documented; acceptable documentation includes modality-specific CME/CEU courses (plus the agenda, outline, and syllabus), confirming letters from the CME/CEU provider, or letters, certificates, or other documents from the manufacturer or other formal training providers.
Recordkeeping and reading
Recordkeeping has been changed by FFDM's introduction in two ways, according to Rush: how records are retained and in what format, and how images are transferred. A facility must keep, in retrievable form, either the original, raw mammographic image as well as the lossless compressed data, or hard-copy films that duplicate the soft copy's interpretive quality. Identifying information must be on each mammographic image, as it is with hard-copy film.
Facilities may transfer, with the recipient's permission, the original or lossless compressed images electronically, Rush said. When comparing digital images taken from different units, it's understood that there may be modest and acceptable variations; the Integrating the Health Enterprise (IHE) mammography subcommittee has been working with vendors to determine how to ensure consistent image display.
As for hard-copy image transfer, facilities must be able to provide a medical institution, physician, healthcare provider, or patient with hard-copy films of primary interpretation quality -- and so all facilities need access to a printer. Printers no longer have to be cleared by the FDA, Rush said, but they must pass all applicable QC tests established by the FFDM manufacturer, as well as the facility's AB's phantom and clinical image review process.
Printers should be dry laser, with a Dmax of 3.5 or greater, a base plus-fog level of less than 0.25, and 16-bit images with at least 12-bit gray levels. They should support true-size printing, and images should be justified so that the chest wall is printed as close to the edge of the film as the printer server is capable. Monitors must be 5K to achieve the resolution required for mammography images.
For DR and CR quality control, each manufacturer's manual will explain the appropriate QC procedures, Rush said. The elimination of wet processing immediately reduces many of the daily QC concerns. Keeping a copy of the most updated QC manual from the manufacturer and following its testing procedures are key, she said. Facilities can also check the ACR's Web site for a list of mandated tests and QC forms for each manufacturer.
QC test retention time frames vary:
- Daily QC tests: Previous 30 days
- Weekly QC tests: Previous 12 weeks
- Monthly and quarterly QC tests: Since last inspection
- Semiannual QC tests: Since last inspection, and/or until the test has been performed two additional times at the required frequency, whichever is longer
Keep records for the last 12 months, since the last annual inspection, or until the test has been carried out an additional two times at the required frequency, whichever is longer, Rush said.
For DR and CR inspections, all tests are similar to film-screen and are performed by the inspector, who, in addition to performing a phantom test, will check the following:
- The MEE or survey performed by the MP
- Personnel training documents
- The latest version of all QC manuals for the equipment
- Whether all QC tests listed in the manuals have been conducted
- Whether all monitor and printer QC tests have been performed per manufacturer's manual
- Whether timely corrective actions have been taken for the tests that failed
Legal considerations
Legal issues surrounding digital mammography are legion, Rush said, particularly since an electronic image can be manipulated in any number of ways, which opens a facility to charges that its radiologists did not interpret an image properly. A facility can show that it is attempting to make image interpretation consistent in numerous ways.
Room lighting: One way to address the interpretation issue is to pay attention to the room lighting in the reading rooms: matching ambient room light to monitor light can reduce radiologists' fatigue, as well as the tendency to window or level images in a room where the light is unbalanced.
Magnification: Also of concern is magnification, whether electronic or geometric: Electronic magnification for the diagnostic analysis of a specific focus can be contested when standard of care concerns would prompt geometric magnification views, according to Rush.
Digitizing prior analog studies: Digitizing film studies and storing them in the PACS can reduce transition time and sensitivity for radiologists when they compare prior analog exams to current digital ones. MQSA requirements allow the digitization of hard-copy priors for comparison, but the interpreting physician must approve their quality, they cannot be used for primary interpretation, and they can't take the place of the hard copy for retention purposes. Digitizers must be cleared by the FDA's Office of Device Evaluation, and images must be of sufficient quality to pass phantom and clinical review if they were submitted to an AB.
Conversion considerations include:
- "Mammogram for presentation" DICOM format
- Lossless, not lossy image compression
- Evaluating digitized image quality by scanning previous true positive images and scan phantom
- Determining which films to digitize
- Whether to perform on-demand conversions or to do a complete conversion
Skin marking: Using standardized skin marking protocols increases both the viability of the interpretation and radiologists' productivity, Rush said. The focus should be on consistent marking -- for example, using a circle for a raised mole, a triangle for a palpable mass, a line for surgical scar, and a pellet as a nipple marker -- since inconsistent use of markers can actually harm patients.
Archiving: For basic operations, archiving only the "for presentation" images is adequate for most facilities. Regarding the "for processing" or raw data, remember that both review workstation and CAD systems may change their processing algorithm over time, so it is important to keep a log of the software version used at the time of the original interpretation.
Computer-aided detection (CAD): Despite the recent negative study on CAD published in the April 5, 2007, issue of the New England Journal of Medicine, CAD has been strongly supported by insurance companies, and offers a double-reading protocol that can be useful in legal situations, according to Rush. If CAD finds a lesion, eliminate the concern or work it up to avoid being held accountable for negligence in court, she said. Should the CAD studies be saved? There are currently no cleared established medical-legal decisions or regulatory requirements that settle this question; traditionally, most facilities have not archived CAD findings, but more and more are choosing to do so.
The bottom line when it comes to walking the legal tightrope of digital mammography? Mind your quality control, Rush said.
"It all comes down to the quality of the image, the adequacy of the equipment, and the competency of the reviewer," she said.
By Kate Madden Yee
AuntMinnie.com staff writer
October 11, 2007
Related Reading
Top 10 considerations for FFDM and PACS integration, October 4, 2007
ACR's withdrawal from NAPBC draws mixed response, August 30, 2007
Digital technology makes headway for breast cancer screening, August 29, 2007
Managing the transition to digital mammography, March 1, 2007
Digital mammography: Not just plug-and-play, October 23, 2006
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