Dr. Tu is Chairman, Department of Radiology, United Medical Center, Washington, DC; Partner at Progressive Radiology, Falls Church, VA; and Clinical Associate Professor of Radiology, The George Washington University School of Medicine and Health Sciences, Washington, DC. Dr. Charafeddine is a Staff Radiologist, Department of Radiology, United Medical Center, Washington, DC; and Radiologist at Progressive Radiology, Falls Church, VA. Mr. Williams is Director, Department of Radiology and Cardiology Services, Department of Radiology, United Medical Center, Washington, DC. Mr. Rothenberg is a third-year medical student at The George Washington University School of Medicine and Health Sciences, Washington, DC.
Digital mammography has proven its effectiveness in breast cancer
detection programs for over a decade. From the patient’s perspective the
screening examination is quick, taking less time than prior analog
film-screen technology. From the technologists’ perspective, digital
provides enhanced throughput, eliminating the need for film
manipulation, cassettes, toxic photographic liquids, and mechanical
processors. From the radiologist’s perspective, the streamlined
integration is intuitive with existing plain film, CT, and MRI viewing
systems, with the obvious benefits familiar to any digital modality.
recently there was only one digital mammographic choice. Though
available in Europe and Canada for years, the recent debut of MicroDose
digital mammography in the United States (U.S.) market improves
fundamental mammographic detector technology. Micro-Dose provides all
the benefits of existing digital mammography with high resolution and
lower dose — with 18% to 50% lower radiation dose than used on other
digital mammography systems, with an average dose reduction of 40%*.1-4 MicroDose
competes with standard mammographic technology as a solution to the
film-screen replacement challenge (for those sites which have yet to
replace legacy film techniques). It also addresses concerns over
unnecessary, nondiagnostic radiation exposure in healthy patients while
providing an edge in a competitive provider market.
MicroDose: Low-dose digital mammography
The MicroDose digital mammographic system is the first to use photon
counting technology, a patented technological revolution in x-ray
detector development. The individual x-ray photon is counted by a
50-micrometer detector element, the smallest in the industry (as much as
4 times smaller). The single-layer detector counts individual photons,
creating very low noise during the digital-to-digital data collection,
and eliminating the analog to digital conversion used by other vendors.
The photon counting technology is unique to MicroDose.5 Also
unique to MicroDose is the image acquisition. By using a multi-slit
pre-collimator and a matching multi-slit post-collimator, only those
x-rays perfectly aligned with the detector are allowed to pass through
the breast. All other x-rays are blocked, as that radiation would only
increase patient dose without contributing to image quality; scatter
radiation, which adds to patient dose and degrades image quality, is
minimized. MicroDose reduces 97% of scatter, enabling the system to
achieve excellent image quality at low radiation.6
The measurement of breast radiation exposure was published by the
Irish Breast Screening Program. The purpose of the study was to compare
radiation dose to the breast per exposure and per exam among the digital
mammography systems of 3 common vendors: Philips MicroDose, Hologic
Selenia, and General Electric Essential. The lowest to highest
craniocaudal (CC) doses (mGy per exposure) were 0.90 (Philips Healthcare
(Philips), 1.36 (Hologic), and 1.39 (General Electric (GE). The lowest
to highest mediolateral oblique (MLO) doses (mGy per exposure) were 0.88
(Philips), 1.44 (Hologic) and 1.52 (GE). The mean glandular doses for a
complete examination (MLO and CC) from lowest to highest radiation dose
(mGy per breast) were 1.86 (Philips), 2.91 (Hologic) and 3.03 (GE). The
study found that the Philips MicroDose system had the lowest mean
glandular dose per image and per exam among the 3 vendors (Table 1).7
Price vs value
Considering differences in price vs value, not all mammograms are
created equal. Price (the financial investment) and value (the weighted
multifactorial health benefit) are not synonymous. The various costs of
digital mammography equipment (standard and MicroDose) are fairly
similar. The vendor add-ons, such as viewing software, workstations,
phantoms, service contracts, financing options, and accessories, can
On the other hand, differences in value are
striking. As healthy people are being screened, the consumer’s
perception of harm from radiation exposure cannot be underestimated. As
customers select a provider, variation in price and value are not
necessarily concordant. The patient calculates value—physician
recommendation, geographic proximity, familiarity of the provider,
reputation, and personal communication—and weighs it against
out-of-pocket cost. Mammography providers are accredited by the American
College of Radiology (ACR) and the U.S. Food and Drug Administration
(FDA), removing much of the variability among various sites.
Coverage and reimbursement are usually driven by third-party payers
and local carrier determination, and are not a factor unless a
non-covered service, such as tomosynthesis, is added on. A customer will
weigh value against cost: time, distance, money, and radiation. The
radiation savings will attract informed customers to the lower-radiation
option. An analogous exploited marketing benefit of lower radiation was
used to promote digital mammography during the analog film-screen to
digital transition. The lower-radiation advantage of MicroDose provides
similar value to an imaging business seeking to enter or expand its
digital mammographic service.
Patients are pleased with the
brevity of the MicroDose exam. The breasts are compressed on a curved
MicroDose patient support assembly warmed above room temperature rather
than to the typical flat, cold ergonomic plate. The warmed support and
compression device provide comfort and reduce the shock of having one’s
breast placed on a cold tray.8 Patients who have returned
from other mammogram studies have been complimentary of their experience
on MicroDose. They request MicroDose realizing the added benefit of 18%
to 50% less dose than other breast imaging practices. Many patients are
fearful of radiation; offering a lower radiation option enhances
patient emotional comfort with the study.
mammography can elevate the reputation of the department and hospital.
The perception of providing cutting-edge technology and lower radiation
dose at the high resolution results in more referrals from healthcare
providers. Lower radiation dose breast cancer detection with the high
resolution provides cache and exclusivity to a facility’s portfolio of
imaging services. Patient feedback to referring providers will attract
more patients to a low dose exam.
Positioning a patient in
the MicroDose machine is similar to placing her in standard mammography
machines. Adjustment controls for the patient support tray are easy to
access and operate with ergonomic foot control paddles. The computer
interface is similar to that of any other computer data entry system.
The elimination of film cassettes, film handling, and the processor
streamlines the exam.
Installation of the
MicroDose machine is simple; the system’s footprint is similar to that
of other vendors. Elimination of the analog filmscreen dark room,
processor, and chemicals does not necessarily enlarge the clinical
space, as a power conditioner and cooling system is needed for the
buildout. The cooling and power conditioner system must be constructed
as a separate, self-contained room to maintain a quiet environment for
the patient. Though not as obtrusive as a magnetic resonance computer
room, there are added installation details for electronic components.
Radiologist image interpretation of the digital mammogram is very
satisfying, commensurate with the recent 2012 study by Cole et al, which
concluded that photon-counting, full field digital mammography is not
inferior to conventional digital mammography. The 50-micron resolution
provides incredible diagnostic-quality images (Figures 1 and 2). The
full-field digital mammograms provide exceptional image quality so that
focal asymmetries are easy to identify, whereas on prior examinations
the opacities were perhaps seen only on one view in prior years (Figures
3 and 4). The detail in dense breast tissue is superb, as well. Border
delineation, microcalcifications, and architectural distortion are easy
to identify with MicroDose. Post-procedure architectural distortion and
fat necrosis, while subtle on prior studies, are very obvious with the
MicroDose 50-micrometer resolution.9
MicroDose improves digital mammography technology by providing high
image quality at low radiation dose. In analog-to-digital conversion,
MicroDose full-field digital mammography is an excellent solution in
replacing a legacy film program, decreasing unnecessary radiation
exposure to otherwise healthy patients while providing market share
advantage in a consumer-driven examination.
The lower dose and
high resolution of MicroDose will be the standard of digital mammography
as imaging centers add more units and replace older equipment with new
- Oduko, J.M. Young, K.C., Burch, A.,: A Survey of Patient Doses from Digital Mammography Systems in the UK in 2007 to 2009. Digital Mammogr. 2010;2:365-370.
- Baldelli P, et al, Comprehensive dose survey of breast screening in Ireland. Radiation Protection Dosimetry. 2010;145:52-60.
Leitz W, Almén A. Patientdoser från röntgenundersökningar i Sverige –
utveckling från 2005 till 2008.
SSM 2010-14, ISSN 2000-0456. Accessed October 9, 2012.
- White paper. Comparison of Dose Levels in a National Mammography Screening Program, Philips Healthcare.
- Sectra microdose mammography. Highest image quality, Half the radiation. 2010.
- Åslund M, Cederström B, Lundqvist M, Danielsson M. Scatter rejection in multi-slit digital mammography. Medical Physics. 2006;33:933-940.
- Baldelli P, McCullagh J, Phelan, N, Flanagan F. Comprehensive dose survey of breast screening in Ireland. Radiation Protection Dosimentry. 2012;145:52-60.
- Philips MicroDose mammography system, technical data sheet, US/Canada. 2012.
Cole EG, Toledano AY, Lundqvist M, Pisano ED. Comparison of radiologist
performance with photon-counting full-field digital mammography to
conventional full-field digital mammography. Acad Radiol. 2012;19:916-922.