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Best Practices in Digital Radiography

Best Practices
in Digital Radiography

Tracy L. Herrmann, M.Ed., R.T.(R); Terri L. Fauber, Ed.D., R.T.(R)(M); Julie Gill, Ph.D., R.T.(R)(QM);
Colleen Hoffman, R.T.(R)(M)(CT); Denise K. Orth, M.S., R.T.(R)(M);
Paulette A. Peterson, M.Ed., R.T.(R)(M)(QM); Randy R. Prouty, B.S., R.T.(R);
Author Sample, B.S.R.T., R.T.(R)(M)(QM)
Andrew P. Woodward, M.A., R.T.(R)(CT)(QM); Teresa G. Odle, B.A., ELS
After completing this article, the reader should be able to:
 Describe the various biopsy types that require specimen imaging.
 List methods of guiding biopsy procedures.
 Explain the reasons behind specimen imaging.
 Describe various methods for imaging specimens.

©2012 ASRT. All rights reserved.
Published by the American Society of Radiologic Technologists, 15000 Central Ave. SE, Albuquerque, NM 87123-3909. ©2012
American Society of Radiologic Technologists. All rights reserved. ASRT prohibits reprinting all or part of this document
without advance written permission granted by this organization. Send reprint requests to ASRT.

Best Practices in Digital Radiography

RADIATION THERAPIST, Spring 2011, Volume 21, Number
1
i

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Best Practices
In Digital Radiography
Tracy L. Herrmann, M.Ed., R.T.(R); Terri L. Fauber, Ed.D., R.T.(R)(M); Julie Gill, Ph.D., R.T.(R)(QM);
Colleen Hoffman, R.T.(R)(M)(CT); Denise K. Orth, M.S., R.T.(R)(M);
Paulette A. Peterson, M.Ed., R.T.(R)(M)(QM); Randy R. Prouty, B.S., R.T.(R);
Andrew P. Woodward, M.A., R.T.(R)(CT)(QM); Teresa G. Odle, B.A., ELS

he amount of radiation Americans are exposed
to as a result of diagnostic medical imaging
increased about sixfold from 1980 to 2006, and
for the first time in history, estimates of medical
radiation exposure nearly equaled those for background
radiation. The reasons for the increase were varied, and
the highest percentage of collective dose (taking into
account the effective dose and the size of the exposed
population) easily was explained by the corresponding
increase in computed tomography (CT) and nuclear
medicine scanning over the same time period. All the
same, the total number of medical imaging studies rose
dramatically, and radiography was no exception. The
number of radiographic and fluoroscopic studies skyrocketed from 25 million in 1950 to 293 million in 2006.
As reports on medical imaging use have been
released, the focus on cumulative dose from regulatory
bodies, clinical societies and the public has intensified,
leading to concerns about utilization of medical imaging. Historically, radiation exposure from diagnostic
medical imaging was not considered a problem, and
there was no evidence that exposure to low doses of
ionizing radiation increased cancer risk. The benefits
of radiography have remained clear over the more
than 100 years of diagnostic medical imaging history. Another fact that has remained clear is the critical role that radiographers play in ensuring patient
radiation safety during medical imaging procedures.
Radiographers must adhere to the “as low as reasonably
achievable” (ALARA) principle by keeping radiation
Best Practices in Digital Radiography

dose as low as is reasonably achievable when performing digital radiography.
As radiographers have adjusted to the advent of
digital radiography, they have had to refine exposure
technique selection and pay closer attention to radiation protection. Newer digital technologies offer many
benefits over film-screen technology, such as time savings, greater dynamic range, wider exposure latitude
and postprocessing capabilities, plus advantages such
as image manipulation that enable radiologists to adjust
images at their workstations. As a result, there is a tendency to be less concerned about exposure technique
and the opportunity to use more radiation than necessary, a trend that often is referred to as “dose creep.”
Exposure techniques that radiographers can use to
ensure that digital images are of optimal quality and
minimal patient radiation dose differ from those used
for film-screen imaging. Because digital imaging technology is relatively new and rapidly changing, radiographers’ skill levels vary, and resources often are scattered and even conflicting. Radiographers, and their
patients, would benefit from a single source that offers
background information, best practices and recommendations on optimizing digital radiography and patient
radiation safety.

Digital Radiography Background

The first form of digital imaging, digital subtraction
angiography, was introduced in 1977 and put to clinical use in 1980. Today, the term digital radiography in
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the literature and in practice encompasses computed
radiography and direct digital radiography. Computed
radiography (CR) is a system that replaced film with a
storage phosphor plate as the image receptor. The latent
image on the exposed plate is scanned by a laser beam
and converted to digital data to produce the image.
Direct digital radiography (DR), which also might be
further classified as direct and indirect image capture,
involves acquiring image data in digital format, without
laser scanning to extract the latent image.
In CR, storage phosphor image plates were first used
to record general radiographs in 1980. The direct capture of x-rays for digital images was introduced with DR
using of a charge-coupled device in 1990. The technology evolved and improved over the next decade and
by 2001, flat-panel thin-film transistor detectors could
expose and display images in near real time. Growth in
digital image receptors has risen slowly and steadily, and
within a few years could increase to double-digit annual
rates. Today’s technology includes a variety of devices
and materials such as storage phosphor plates, chargecoupled devices, thin-film transistors, photoconductors
and x-ray scintillators. Cassette-based and cassette-less
systems have blurred the lines between CR and DR.
An analysis by the technologies market research firm
Technavio reported that the global digital radiography
market could increase by a compound annual growth
rate of 3.3 percent through 2014. The complexity of the
operation of these systems has created misconceptions
about the best practices for the use of digital radiography.
In general, radiography examinations represent
74 percent of all radiologic examinations performed
on both adults and children in the United States, and
contribute to about 40 percent of radiation exposure.
Although much attention in recent years has focused
on lowering CT dose in particular, the prevalence of
radiographic examinations, exposure and a rise in transition to digital image receptor technology necessitates a
thoughtful and thorough examination of best practices
for radiographers regarding digital exposure techniques
and radiation safety.

Dose

When following the ALARA principle, radiographers should minimize patient exposure from digital

Best Practices in Digital Radiography

radiography procedures. The use of digital image receptors can result in lower radiation dose than the use
of film-screen image receptors, without loss of image
quality. Using digital image receptors requires careful
and consistent attention to institutional protocol and
practice standards, however. Conventional film-screen
radiation exposure techniques are based on the specific
film-screen system and the conditions under which the
radiographer processes the film. Digital radiography
separates acquisition, processing and display, which
enables a radiographer to produce an image that has
acceptable diagnostic quality, but could be underexposed or overexposed. Adjustments to compensate for
exposure technique errors can be made at the time of
display, although doing so is not a best practice. The
best practice is to select the appropriate exposure
technique factors for the patient’s size and condition,
based on a planned exposure system designed in collaboration with radiologists, to determine adequate
image quality for diagnosis.
Image quality depends heavily on contrast, or the relative differences in brightness or density in the image.
Image contrast has two primary components, subject
contrast and display contrast. Subject contrast is related
to the absorption of the x-ray beam by the subject’s tissues. Display contrast can be adjusted in postprocessing
and by adjusting the monitor display’s window width.
Very low contrast (many shades of gray) makes it difficult for a radiologist to differentiate between structures
and identify anomalies or pathologies; an image must
have contrast to demonstrate different structures and to
be diagnostically useful. Very high contrast reduces the
image to a scale of mostly black-and-white brightness
or densities, which hinders visibility of the anatomic
details. In digital imaging, contrast is the ratio of brightness of adjacent structures to one another, and gray
scale represents the range of brightness levels.
Subject contrast is determined by different absorption of the x-ray beam by various tissues, anatomic
thicknesses and tissue densities in the body and the
penetrability of the beam primarily controlled by kVp.
Unlike image contrast, subject contrast cannot be
manipulated or recovered with postprocessing; it is
directly affected by how the x-ray beam is attenuated in
anatomic tissues, such as bone and soft tissue.

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The ability to adjust display brightness and contrast
during postprocessing can affect radiographers’ attention to the primary principle of radiation protection:
optimal image quality with minimal patient exposure.
Radiographers must pay careful attention to all aspects
of radiographic exposure technique to provide diagnostic image quality and minimize patient exposure, helping to maximize benefit over potential harm. In addition, the wider range of radiation intensities that digital
image receptors can detect has allowed for a wider range
of values to be processed digitally to display a diagnostic
quality image. Because image receptor exposure information is not apparent from the examination or recorded for each digital examination, there is a further disconnect between image capture and the resulting patient
exposure. A best practice in digital radiography is
the consistent inclusion of information regarding the
image receptor exposure in the image data provided
throughout the image archiving process.
In digital radiography, the computer automatically
adjusts an image that is overexposed to ensure that the
image is of diagnostic quality. This automatic adjustment, separation of image acquisition and display and
lack of available dose information can contribute to
increased patient exposure. What’s more, an excessive exposure to a patient during a digital radiography
examination does not affect image quality, except at
extremely high levels of exposure. In fact, the decreased
image noise that results from additional exposure can
lead to a corresponding decrease in complaints from
radiologists regarding image quality. In turn, radiographers might be inclined to adjust exposure technique
to slightly increase the amount of radiation and subsequently patient radiation dose.
These factors have contributed to dose creep and a
gradual increase in patient exposure. Radiographers,
often faced with feedback that unwittingly reinforces
slight overexposure and lacking the visual cues that
density offered in film-screen imaging, often choose
the path of least resistance: increased exposure technique, decreased chance of image noise and avoidance
of repeats.
Many standard practices and the control of dose
creep require careful review and strict adherence to
sound radiation safety practices to minimize patient

Best Practices in Digital Radiography

dose. Radiographers also need access to collected and
standardized information at the institutional and national levels to help them better navigate the transition to
the best practices for radiation safety in digital imaging.
Avoidance of repeat exposures, careful use of shielding
and beam restriction, clearly established accepted ranges
for exposure indicators (EIs) and other practices will be
covered in the Best Practices discussion below.

Social Marketing and Radiation Safety
Initiatives

Issues such as dose creep have not gone unnoticed.
National and global attention have focused on medical
radiation, and several initiatives have begun educating
radiographers, physicists, radiologists, referring physicians and the general public. One such initiative, the
Image Gently campaign sponsored by the Alliance for
Radiation Safety in Pediatric Imaging, began in 2008
to promote radiation protection for children who have
received medical imaging procedures. With an initial
focus on reducing radiation dose to children undergoing CT examinations, the campaign soon progressed
to fluoroscopic and interventional procedures, nuclear
medicine and other medical imaging including routine
digital radiography. In 2011, the campaign released a
safety checklist for performance of DR examinations
on pediatric patients. More than 14,000 medical professionals have taken a pledge to minimize radiation
dose to children and the campaign’s pediatric CT protocol has been downloaded from its website more than
26,000 times. More recently, the American College
of Radiology (ACR), ASRT, American Association
of Physicists in Medicine (AAPM) and Radiological
Society of North America jointly developed the Image
Wisely campaign to lower the amount of radiation used
in medically necessary imaging and to eliminate procedures that are unnecessary.
Much of this change was brought about by media
reports linking CT scans to childhood cancer. However,
once ionizing radiation from medical imaging moved
into the public arena, medical professionals could no
longer deal with the matter in isolation. According to
the ACR, the radiology community alone had focused
on patient radiation safety issues until these potential
hazards were publicized. Other members of the medical

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community and the public now see the issue more
clearly. Multiple organizations and individuals have
worked together to address the problem. The Alliance
for Radiation Safety in Pediatric Imaging, which was
founded by four imaging organizations, continues to be
a leader in radiation safety initiatives.
There also have been international efforts to
improve medical radiation safety. The United Nations
Scientific Committee on the Effects of Atomic
Radiation (UNSCEAR) published a report in 2010 that
described a strategic plan through 2013. UNSCEAR
asked the public, authorities and scientists to be more
aware of radiation dose in medicine. At a 2010 meeting, UNSCEAR called for improved data collection,
analysis and dissemination of information for patients
and those exposed to radiation occupationally. The
International Commission on Radiation Protection
has updated reports and recommendations and the
International Atomic Energy Agency launched an
action plan in 2002 aimed at reducing patient exposure
to radiation. The plan included an informational website for patients about radiation protection.
The World Health Organization (WHO) joined
with other organizations and agencies in 2010 in calling
for global sets of evidence-based referral guidelines for
medical imaging. The European Commission committed to developing guidelines for its member states
and has aimed to compel member states to adapt their
national regulations and quality assurance programs to
meet more standardized and stringent requirements.
The Society for Pediatric Radiology held a 2004
white paper conference on Feb. 28, 2004, in Houston,
Texas, that summarized the need to emphasize the
ALARA principle in digital imaging. The white paper
conference faculty recommended a team approach to
dose management. Other recommendations included
improved training of radiographers and standardization of nomenclature among manufacturers to assist in
understanding and minimizing dose, improved dose
feedback, and development of standards in digital
radiography. The findings and recommendations were
published in an October 2004 supplement to Pediatric
Radiology, the December 2004 issue of Radiologic
Technology and the February 2005 issue of the American
Journal of Roentgenology.

Best Practices in Digital Radiography

In 2010, the U.S. Food and Drug Administration’s
(FDA) Center for Devices and Radiological Health
began an initiative to decrease unnecessary exposure
from medical imaging procedures. As a result the
FDA has supported the development of educational
materials and a safety checklist for digital radiography
via the Image Gently campaign. The FDA also has
recommended that manufacturers design medical
imaging equipment with pediatric populations in mind.
Through education, research and reports in the literature and change in practice, culture change can occur.
Much work still can be done to compel the culture and
practice changes needed to ensure radiation safety and
minimize patient dose in digital radiography.

ACR Practice Guideline for Digital
Radiography

The ACR developed a practice guideline for digital
radiography in 2007. The document’s intent was “to
provide guidance and assistance in the understanding
and clinical use of digital radiography equipment in
order to deliver optimal image quality at appropriate radiation doses, and to ultimately provide excellent safety and care for patients undergoing digital
radiography examinations.” In general, ACR practice
guidelines for any examination or process undergo
literature and field review, summary of expert opinion
and informal consensus that results in recommended
conduct. The guidelines are not intended to be legal
standards of care; providers can use them as the basis
for practice and modify them according to individual
circumstances and resources.
The ACR guideline on digital radiography provides
information lost in the gap between film-screen and
digital imaging, and some of the key points of the
guidelines are included in this paper. By clearly outlining information such as personnel qualifications, grid
use, prevention of dose creep and determining proper
exposure factors, the guidelines laid the groundwork
for facility protocols and standardization of digital
exposure technique. The ACR guidelines also compare film-screen and digital technologies, helping
radiographers and other medical professionals better
understand the nuances they face in working with
digital imaging.

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Scope of White Paper

The ASRT has championed radiation protection in
digital imaging for all age groups through its support
of and participation in the Image Gently and Image
Wisely campaigns. In addition, ASRT has a continued
history of promoting these areas of professionalism
through publication of educational and promotional
materials for the public and the medical imaging community. The Consistency, Accuracy, Responsibility and
Excellence in Medical Imaging and Radiation Therapy
(CARE) bill can help provide the foundation for national uniformity of licensure laws. The ASRT supports
efforts toward the passage of the CARE bill to promote
minimum standards in each state that ensure only educationally prepared and clinically competent radiologic
technologists perform radiographic examinations and
radiation therapy procedures. This white paper is a
significant continuation of ASRT’s dedicated efforts in
promoting radiation protection for patients and professionalism for radiologic technologists.
This white paper combines information from trusted
sources such as the ACR guidelines, textbooks, professional and government organizations and periodical
literature on exposure technique and patient exposure.
The information gathered aims to support preparation
of radiographers for digital radiography practice and to
examine digital radiography’s best practices for a balance
of optimal image quality and patient radiation safety.
Radiographers assume extensive responsibility in the
radiation safety of patients. The ACR white paper on
radiation dose in medicine places final responsibility for
additional action before radiation exposure on radiographers. Further, the paper states that “technologists are
responsible for limiting radiation exposure to patients
by ensuring that proper procedures and techniques are
followed… .”
Radiographers who perform digital radiography
examinations must recognize their responsibility in
understanding how to optimize digital images while
minimizing radiation dose to patients. As the “experts”
on exposure technique in radiology teams, radiographers should be proactive in remaining up-to-date on
the basics of radiation protection and new technologies.
The best practices and recommendations included
in this white paper serve as a resource for radiographers

Best Practices in Digital Radiography

who perform digital radiography examinations. This
white paper is not, however, an all-inclusive document,
nor should any of these recommendations be taken as
superseding institutional policy or state regulations. In
addition, much like digital technology, it is meant to be
a fluid, living document.

Step-by-Step Best Practices

Radiographers need to take responsibility for understanding and appropriately performing digital radiography procedures because it is their professional duty and
an essential component of the radiographers’ practice
standards and code of ethics. Aside from preparing for
digital radiography examinations through attainment of
proper education and skills sets, there are a number of
ways before, during and after examinations that radiographers can optimize exposure technique and minimize
radiation exposure.

Before the Exam Begins

Because radiographers usually are the first, and often
the only, medical professional to interact with patients
who are scheduled for radiology examinations, radiographers are charged with a great deal of responsibility
even before examinations begin. Ensuring that patient
radiation safety is maintained and exposure minimized
requires regular attention to several matters before capturing the images. Some of the issues are common to
the film-screen environment, but reiterated here.
Procedure Validity
As a patient advocate and the last medical professional to potentially screen for appropriateness before
performing an examination, the radiographer has
a responsibility to recognize and take action when
an incorrect exam is ordered. In an ASRT survey of
radiographers conducted for the Image Gently campaign, nearly 12 percent of respondents cited “unneeded
exams ordered by doctors” as contributing to or causing
excess radiation exposure when performing pediatric
digital radiography. Inappropriate diagnostic imaging
examinations unnecessarily add to cumulative radiation
dose in patients. The radiographer might be the only
person who has the opportunity to recognize that the
examination is a duplicate or is questionable in terms

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of indication or appropriateness. Radiographers should
consult with the radiologist or ordering physician or
request additional information from the ordering physician that can further indicate the correct procedure to
be performed when there is a suspicion of an inappropriate exam order.
On a broader scale, increased utilization of diagnostic medical imaging has added to increased patient radiation doses. A higher frequency of high-dose examinations can directly affect individual and collective dose.
The issue of imaging overutilization is being addressed
globally with calls for standardizing of image justification, along with social media campaigns and intervention of payers or other third parties.
Organizations such as the ACR have addressed
utilization by developing guidelines to help referring
physicians select the appropriate imaging procedure.
An example is the ACR Appropriateness Criteria,
evidence-based guidelines developed by panels of
experts in imaging; the criteria cover several types of
diagnostic imaging and therapeutic uses of imaging and
ionizing radiation. The World Health Organization has
proposed development of global guidelines for appropriate referrals to medical imaging. WHO hosted a
conference in March 2010 with 36 experts from around
the world; the experts recommended development of
the guidelines under WHO’s umbrella. The guidelines
are expected to include radiation dose level for examinations, along with efficacy ratings and a grade for
strength of existing evidence regarding each examination’s efficacy.
Tracking of previous examinations also can help
radiographers identify duplicate examinations before
beginning the procedure. Reviewing health records
can help spot duplicate examinations, but patients may
have imaging examinations performed by any number
of providers within a given time period. Many international organizations and agencies have approved or
developed systems that track radiographic procedures
in a fashion similar to vaccination records. Using a
system-based approach that standardizes input from
providers rather than patients could help facilitate identification of duplicate examinations and recording of
cumulative dose. In addition to identifying duplicate
examinations, a radiographer must review the patient’s

Best Practices in Digital Radiography

health history with the patient. Important information can be obtained by asking routine questions of the
patient to further validate the ordered examination and
to determine whether the patient should have an examination that involves radiation. It is a best practice in
digital radiography for the radiographer to carefully
review the examination ordered to prevent potential
duplication and to ensure appropriateness as related
to the patient’s history. If there is a possibility that the
examination might be inappropriate, the radiographer then should consult with the radiologist and/or
ordering physician to ensure the appropriate examination is being obtained.
Departmental Standards and Protocols
National or international guidelines and accreditation requirements provide the foundation upon which
radiology departments can base their specific protocols for all imaging examinations, including digital
radiography examinations. For example, if a radiology
department does not develop exposure technique
charts or make them available to radiographers, it is
more difficult for radiographers to manually set milliampere seconds (mAs) and optimal kilovoltage peak
(kVp). When systems have automatic exposure control
(AEC), other variables such as AEC detector cell configuration and backup time also can be standardized.
Departments should establish protocols for common
digital radiography examinations and conspicuously
post them for radiographers’ use.
Radiographers should expect to consult with radiologists and vendors to refine information provided
by vendors for exposure techniques and protocols.
Nuances in equipment, personal preference and learning curves for digital technology all could be factors
that contribute to inconsistencies in exposure techniques. The best way for a radiographer to ensure consistency is by following department protocols that are
based on established clinical research and guidelines.
Advantages of digital radiography include the ease
of incorporating images and order entry into existing radiology information systems (RIS) and picture
archiving and communication systems (PACS). In
many ways, this has positively affected radiology
department workflow, eliminating many manual

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steps and improving patient care and efficiency.
For example, in facilities that have a RIS, electronic
health records (EHRs) and a PACS, the process from
order entry to report generation involves little to no
human interaction. The RIS and modality worklist
system schedules a worklist for the digital radiography
equipment, which bundles the information with the
acquired images and sends it to the PACS. This information is available at the radiologist’s workstation, and
if the radiologist uses speech recognition software,
the report is generated automatically for radiologist
approval, then archived and distributed to referring
physicians through the EHR.
The lack of human interaction is one reason that
adopting a new technology and automating various
ordering and hand-off processes can be less disruptive to patient care and decrease the potential for
errors. Another is that the transition to a digital
environment streamlines workflow. The transition
from a film to a digital radiography environment can
initially be very daunting when digital radiography
is the first, only or final modality transitioned in a
given radiology department, it is imperative to take
steps to assess, prepare and establish procedures for
digital image interpretation and storage. This preparation should involve technologists, who must have
the proper tools and procedures in place to do their
jobs correctly.
Though digital technologies simplify workflow,
planning for workflow adjustments is critical. It begins
with looking at current workflows for acquiring and
interpreting images, along with quality assurance
(QA). Radiographers and other team members must
decide whether to attempt to duplicate workflow with
digital technologies or improve them. They also must
work together—and with vendors—to identify potential gaps in workflow or function. The team must then
document the workflow and standardize protocols
and procedures. Radiographers must follow the
protocols and standards set by their departments
and actively participate in establishing and further
developing protocols that ensure consistency of
diagnostic quality images and improved practices
to reduce patient radiation dose. This is a critical
best practice in digital radiography.

Best Practices in Digital Radiography

Screening for Pregnancy
As with film-screen radiography, the radiographer
needs to carefully review the patient’s history before
beginning the digital examination to determine whether the patient is pregnant. How to verify pregnancy
varies slightly according to department protocol, but
typically includes asking women of childbearing age if
there is any possibility they are pregnant. The radiographer can use physical signs and lead-up questions to aid
in determining possible pregnancies. Tact and professional communication help put the radiographer and
the patient at ease.
The exact protocol for proceeding once a patient
responds that she might be pregnant is specific to the
department. Departments often require written documentation before pregnancy screening can occur, and
the patient’s referring physician or radiologist generally
decide whether pregnancy testing is necessary. The
physicians also decide whether the patient should have
an alternative imaging examination to avoid radiation
exposure. The screening of patients for potential
pregnancy is an essential best practice for radiation
safety in digital imaging.

Image Acquisition

The foundations of radiographic exposure technique
selection don’t change simply because a radiographer
uses a different type of image receptor. When producing images using digital technologies, radiographers
still must determine the radiation exposure needed to
produce a quality image for diagnostic interpretation. A
quality image has sufficient density/brightness to display anatomic structures, an appropriate level of subject
contrast to differentiate among the anatomic structures, the maximum amount of spatial resolution and a
minimal amount of distortion. In addition, limiting the
amount of quantum noise/mottle as a result of too few
x-rays reaching the image receptor is a common concern
in digital imaging. Many variables affect the acquisition,
processing and display of a quality image and the advent
of digital imaging has created new challenges for the
radiographer.
Digital imaging technologies continue to evolve and
vary in their construction and how the latent or invisible image is acquired. Common digital image receptors

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in routine radiography include computed radiography
photostimulable image receptors, charge-coupled
devices and flat-panel thin-film transistor detectors.
Because the technology is changing rapidly, digital
image receptors will be discussed in general and specific differences among detectors will be described when
appropriate. Standardizing exposure technique and
emphasizing sound practices can help ensure a radiographer follows the ALARA principle when performing
digital examinations.
Standardized Exposure Technique
A digital image receptor responds to a large variance
in x-ray intensities exiting the patient. As a result, the
digital image receptor also has a wide dynamic range.
In addition, computer processing produces “acceptable” images even when significant overexposure has
occurred. Because of this, the standardization of exposure techniques used in a radiology department has
become even more essential. Digital technologies are
progressing rapidly, and departments cannot rely solely
on vendors and professional organizations to set technical standards. Setting department policies and protocols
helps the radiology department ensure consistency in
diagnostic quality of digital examinations and minimizes
the potential for exposure technique selection errors.
Standardizing exposure techniques, however, does
not mean that radiographers use the same protocols for
all patients in all situations. Exposure techniques must
be adjusted for a patient’s specific history and condition.
Appropriate and consistent use of exposure technique
charts, adequate kVp and AEC is essential to consistently producing diagnostic images while minimizing
patient radiation exposures.
Kilovoltage Peak (kVp)
Image quality is dependent on a sufficient amount
and energy of x-rays reaching the image receptor. As a
general rule, kVp and mAs should be selected for digital
radiography in the same manner as the exposure factors
are selected for film-screen image receptors. However,
the amount of exposure (mAs) to the digital image
receptor does not directly affect the amount of density/
brightness produced as a result of computer processing. Adequate penetration of the anatomic part (kVp) is

Best Practices in Digital Radiography

needed to create the differences in x-ray energies exiting
the part to produce the desired level of contrast. Given
adequate penetration of the part, kVp has less of an
effect on the contrast of the image because of computer
processing. A quality digital image is produced following adequate penetration (kVp) along with enough mAs
to produce a diagnostic image with a minimal amount
of quantum noise/mottle.
The use of higher kVp values along with an appropriate decrease in mAs is a practice advocated by some
imaging professionals for many adult digital exams.
Increasing the kVp by 15% with a corresponding
decrease in mAs reduces patient radiation exposure.
Because increasing kVp decreases image contrast and
increases scatter radiation reaching the image receptor,
the use of a grid may be necessary. Specifying the kVp
level for digital exams along with grid use are important
exposure technique variables to standardize in a radiology department. A best practice in digital imaging is
to use the highest kVp within the optimal range for
the position and part coupled with the lowest amount
of mAs needed to provide an adequate exposure to
the image receptor.
Automatic Exposure Control
The AEC for digital radiography systems operates
identically to AEC used for film-screen systems. It is
critical that the AEC be properly calibrated to match
the image receptor system before clinical use. AEC systems use radiation detectors called ionization chambers
that are preprogrammed based on phantoms. These
systems traditionally come equipped with three ionization chambers; some newer AEC systems have five
detectors from which to choose. It is important that
radiographers choose the appropriate detector configuration for the examination.
The purpose of AEC is to control exposure time, so
use of this feature is critical to patient radiation safety.
AEC helps control total mAs, but the radiographer
still is responsible for selecting optimum mA (if set)
and kVp for an examination when using AEC, and
technique charts help ensure consistent use of these
factors with AEC. Although AEC use is recommended
in most radiographic examinations to help reduce
patient radiation exposure, there are times when it

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can’t be used. For example, if the anatomy of interest
is too small to cover at least one of the AEC’s detector
cells, AEC will not work and should not be used.
If AEC is used when the anatomy of interest is too
small, those areas of the detector not covered by the
patient’s anatomy receive more radiation than the area
of interest, causing the AEC to terminate the exposure
time prematurely and causing quantum noise in digital
images. This is especially important to consider when
performing pediatric radiography. Using AEC to image
anatomy close to the edge of the patient’s body, such
as the clavicle, also can cause the time of exposure
to prematurely terminate and result in insufficient
exposure to the image receptor resulting in increased
quantum noise. Finally, presence of large metal artifacts
such as orthopedic hardware can contraindicate the
use of AEC. Unless large metal objects can be moved
away from the area of interest, they create unexposed
areas over the AEC detectors that can affect the time of
exposure and potentially overexpose the patient.
Although use of the unit’s AEC is the best way to
control the amount of radiation exposure regardless of
the type of image receptor, doing so requires accurate
positioning and systematic calibration of the AEC.
Radiographers should ensure that the anatomy of
interest covers most of the AEC detector(s) used, and
place emphasis on proper positioning for an examination. It is important for radiographers to follow
department protocols and exposure technique charts
regarding use of AEC. A best practice in digital radiography is to use AEC when indicated and to use
AEC that has been calibrated to the type of image
receptor to provide a consistent exposure to the
image receptor.
Anatomically Programmed Radiography and
Exposure Technique Charts
Anatomically programmed radiography (APR) is
a system of preprogrammed exposure technique settings that is organized by position and procedure and
set through the control panel of the radiography unit.
APR settings commonly provide recommendations
for small, medium and large adult patient sizes and
include a combination of AEC and manual exposure
technique settings. It is important for the radiographer

Best Practices in Digital Radiography

to assess the programmed exposure technique for its
appropriateness to each radiographic examination.
An exposure technique chart also can be used to
standardize exposure techniques according to patient
size, procedure and position. Use of exposure technique
charts is required in some states and as a standard of
care per The Joint Commission. Departments can provide the charts with relatively simple spreadsheets that
are posted and accessible to radiographers. Although
exposure technique charts take time and effort to
develop accurately, they prevent exposure technique
errors. Routine use of the charts can provide consistent
and accurate radiation exposure to the image receptor,
thereby reducing patient dose.
Providing exposure technique charts establishes
department standards and eliminates much of the
confusion and concern regarding appropriate use
of variables such as kVp, mA, grid use and SID. The
charts also allow radiologists and technologists to work
together to determine an acceptable level of radiation
exposure that provides diagnostic quality images within
the ALARA principle. A thorough exposure technique
chart includes, at a minimum, the following variables
for each x-ray tube:
 Backup exposure time or mAs (if set).
 Source-to-image receptor distance (SID).
 kVp.
 Focal spot size.
 mA (if set).
 Use of a grid and the grid ratio.
 AEC detector(s).
 Acceptable exposure indicator range.
Typically, exposure technique charts are developed
based on patient thickness. Although measuring patient
thickness in adult imaging may not be practical in all
departments, well-developed charts that are consistently used can reduce the variability in exposure techniques that occurs during digital imaging. The charts
don’t take the place of radiographers carefully assessing
individual patient pathology, condition and unusual
circumstances because exposure technique charts are
designed for the average or typical patient. Exposure
technique charts should be monitored and revised continuously to ensure exposure techniques are producing
diagnostic images within the ALARA principle. A best

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practice in digital radiography is to use exposure
technique charts that are continuously improved and
applicable to a wide range of patient sizes.
Collimation and Electronic Masking
It is essential that radiographers carefully use collimation to the appropriate anatomy of interest when
performing digital examinations to minimize patient
exposure and prevent errors in processing of the digital
image data. By limiting the anatomy that receives radiation, a smaller area of the patient’s tissue is exposed,
thereby reducing patient dose and minimizing scatter
radiation to the image receptor. Collimation is very
important in digital radiography because digital image
receptors are more sensitive to low levels of radiation,
and the resulting digital image might demonstrate
reduced image contrast because of excess scatter radiation striking the receptor.
Digital radiography systems have software that provides electronic masking (collimation) based on recognition of the borders of the exposed area of the image
receptor; radiographers may need to adjust the electronic masking to accurately align it to the exposure field.
The unexposed area of the image outside of the collimated exposure field has a bright appearance on the display
monitor that affects viewing conditions. The purpose
of the masking is to reduce the eye strain of the viewer
caused by high brightness levels. To document appropriate collimation for an examination, the mask should be
applied to the image with a small distance between the
exposure field and the start of the mask overlay.
Masking, shuttering or cropping should not be used
as replacements for beam restriction achieved through
physical collimation of the x-ray field size. The appropriate use of masking is to act as an overlay on the areas
outside of the collimated exposure field; masking never
should be used to cover anatomy that is contained within the exposure field at the time of image acquisition
because of legal and radiation safety concerns.
The appropriateness of including multiple exposures
on one image receptor depends on the type of image
receptor being used. If the image receptor is capable of
acquiring more than one image prior to image processing, the decision to do so should be determined by the
department protocol established in consultation with

Best Practices in Digital Radiography

the radiologist. When multiple fields are included on one
image receptor, radiographers should keep the exposure
fields aligned, avoid overlapping fields and use flexible lead shielding on all areas of the receptor not being
exposed by the x-ray beam, regardless of image receptor
technology. The literature includes several reports stating that the use of collimation that uses a smaller field
size could help lower radiation doses to patients.
A best practice in digital radiography is to collimate the x-ray beam to the anatomic area appropriate
for the procedure. Electronic masking to improve
image viewing conditions should be applied in a manner that demonstrates the actual exposure field edge
to document appropriate collimation. Masking must
not be applied over anatomy that was contained in
the exposure field at the time of image acquisition.
Shielding
Lack of patient shielding can contribute to increased
patient dose. Shielding is particularly important to protect
anatomic areas near the exposure field, but should not
interfere with obtaining diagnostic information. At a minimum, a patient’s gonads should be shielded when within
5 cm of the edge of a properly collimated x-ray beam.
Radiographers should follow department guidelines
for proper shielding. This is particularly critical for
digital examinations because shielding can interfere
with the equipment’s ability to optimize display for the
region of interest if the shielding material is included as
part of the data used for processing the image. Shielding
is a fundamental radiation safety practice that remains
important when performing digital radiography. A
best practice in digital radiography is the use of lead
shielding for anatomic parts that are adjacent to the
x-ray field.
Anatomic Side Markers
Radiographers should use lead anatomic side
markers that are placed on the image receptor
for digital radiography examinations. Electronic
annotations of anatomic side on the image during
postprocessing are not an acceptable substitute for
lead markers captured during the exposure to the
image receptor as part of the original image. Failing
to use lead markers to denote the side or to identify

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the radiographer performing the examination can be
a legal issue. The ACR also emphasizes consistent
use of lead markers in its digital practice guidelines. A
best practice in digital radiography is the consistent
use of lead anatomic side markers captured on the
original image during the x-ray exposure.
Grids
The fact that digital imaging technology is more
sensitive to low-level radiation exposure makes the use
of antiscatter grids critical to ensuring quality images.
A major disadvantage of using a grid is the required
increase in radiation exposure to the patient. However,
using a grid decreases the amount of scatter radiation that reaches the image receptor and improves
image quality. Department guidelines and exposure
technique charts should assist radiographers in determining whether to use grids for specific radiographic
examinations. As a general rule, grids are appropriate for anatomy that is 10 cm thick or more and for
examinations using kVp settings of 70 or higher. Grid
use could vary for pediatric patients, however, or
based on department protocol or recommendations of
the equipment vendor. In addition, it is important to
consult with the vendor to match the appropriate grid
design to the digital imaging system to prevent artifacts. A best practice in digital imaging is the use of a
grid with specifications recommended by the digital
imaging equipment vendor, generally for body parts
that exceed 10 cm.
Positioning
Accurate positioning is critical to radiographic
image quality. Positioning errors have been identified
in several studies as the number one reason for having to repeat digital radiography examinations. The
increase in exposure latitude in digital radiography
seems to have led to an overall reduction in repeats,
and the cause of most repeat imaging has shifted to
positioning errors. Inaccurate positioning of the part
relative to the image receptor, along with a poorly
collimated exposure field, often results in poor quality digital images. Independent of the image receptor
system, it is critical that all positioning be performed
accurately according to national standards and depart-

Best Practices in Digital Radiography

ment protocol with accommodation for the patient’s
condition to prevent the need for a repeat exposure.
Immobilization is a critical component of positioning that helps to prevent retakes, particularly in examinations of pediatric patients. The radiographer must
note that some immobilization devices used in positioning patients, such as sandbags and sponges with
plastic coverings, can cause artifacts in digital imaging and must be kept out of the exposure field. A best
practice in digital imaging is to use immobilization
devices when needed and prevent repeat exposures
by appropriately positioning the patient.

Considerations for Pediatric Patients

Pediatric patients are not just small adults; they
require special attention from the radiographer.
Therefore, many of the factors radiographers must consider during adult radiographic examinations should be
given special consideration when performing radiography of pediatric patients. Pediatric patients have developing organs and are up to 10 times more sensitive to
ionizing radiation than are adults. They also have longer
life expectancies, so attention to ALARA for pediatric
digital examinations is essential.
Beam Attenuation and Tissue
Tissue thickness, body habitus and tissue composition result in differences in x-ray beam attenuation.
This is the basis on which digital and all radiologic
imaging creates radiographs. For example, muscle tissue
is more dense than fat tissue, and requires an increase
in technique so that the beam can adequately penetrate the muscle tissue, regardless of the patient’s size.
Reconfiguring techniques applied to adult tissues for
use on children does not work; the dimensions of children’s anatomies vary much more than those of adults.
This makes it difficult to estimate exposure technique
because patient thickness depends not only on a child’s
age, but also on the child’s individual characteristics.
In addition to the variation in growth along the age
continuum and from one child to another, children’s
body parts grow at different rates. For example, the
femur of an infant is one-fifth the size of an adult femur,
and represents the extreme in development from birth
to adulthood. On the other hand, an infant’s skull grows

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more slowly, only tripling in size by adulthood. Grids
typically are not used when anatomy is less than 10 cm
thick, so radiographers must carefully consider whether
to use grids based on the patient’s actual size and tissue
composition. Because the tissue composition is different in pediatric patients, a grid should not be considered
for body parts less than 12 cm in thickness.

systems that shields not interfere with the software’s
ability to identify the exposure field. Protocols may
be established that allow for the use of a shield on one
projection when multiple projections in the same area
of the gonads are required. Radiographers should follow department protocols regarding collimation and
shielding for pediatric examinations.

Exposure Technique
In pediatric radiography, APR and exposure
technique charts must be adjusted for patients who
may vary from premature infants to obese adults.
Radiographers must carefully select optimal kVp
to penetrate the pediatric patient’s anatomy under
study. Selection of appropriate kVp is more critical
with exams of infants and children because their bodies typically display less subject contrast. Infants and
young children have bones with less calcification than
adult bones, which requires lower kVp compared to
that required in adult exams. As a result, radiographers
can reduce kVp, but still adequately penetrate the bone
with the x-ray beam for a diagnostic-quality image.
Adult AEC settings cannot be used for pediatric
patients. Radiographers who use AEC settings for
imaging pediatric patients should follow the Imaging
Gently digital safety checklist, which emphasizes
that radiographers must be diligent in ensuring that
the appropriate kVp, backup time, image receptor and detector (or detectors) have been selected.
Radiographers may need to use manual technique
selection in pediatric radiography when the part is
smaller than the ionization chamber.

Positioning and Immobilization
Because pediatric patients have more trouble complying during positioning and image capture, the
anatomy might not be centered accurately or consistently within collimation boundaries compared with
adult positioning. In some digital imaging systems,
improper centering affects how the digital system software forms the image. Immobilization devices may
help ensure that the pediatric patient can be imaged
without need for repeat. However, care needs to be
taken when using some standard immobilization aids
that can create artifacts on digital image receptors. A
variety of toys, books and other distraction tools also
can be used to help comfort or focus pediatric patients
to support their compliance with the positioning
requirements of the procedure.
A best practice in pediatric digital radiography is
to take appropriate actions to use ALARA principles,
radiation protection, and size-appropriate exposure
techniques. Proper positioning and immobilization
also are necessary to decrease repeat exposures.

Collimation/Shielding
Appropriate collimation and minimizing the anatomy exposed to radiation can reduce radiation dose to
pediatric patients. As with adult examinations, proper
alignment is critical to ensure essential anatomy is
included in the image. Studies have found that poor
collimation of lumbar spines led to unnecessary radiation exposure for children. Proper shielding also can
help reduce dose. Lap shields and half-shields can help
protect children’s gonads. Specially shaped shields
can be helpful for male gonads or female breasts. It is
important, however, with some digital radiography

Best Practices in Digital Radiography

Image Critique

Radiographers must ensure that they thoroughly
critique their radiographs to review each image for the
following:
 Correct patient and examination information.
 Brightness/contrast.
 Exposure indicator.
 Processing errors.
 Required anatomy.
 Positioning accuracy.
 Artifacts.
In short, the radiographer’s review is important to
ensure that the images contain the information the radiologist needs to interpret the image for pathology and
clinical reporting.

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Image Appearance
The visual cues of underexposure and overexposure
errors are more difficult to recognize or are missing
in digital radiography as a result of what happens to
the image data during imaging processing. A common misconception is that the digital system “fixes”
exposure errors, when in fact it does not. During the
analysis of the image data, the potential exists for the
digital system to make adjustments to the image data
so that the image has an acceptable brightness level in
the presence of underexposure and overexposure. The
exposure error remains regardless of what occurs during imaging processing. Underexposure appears on the
digital image as quantum noise/mottle that is clearly
visible in the thicker portions of the anatomy contained
in the image. Overexposure results in a loss of image
contrast throughout the image because of the increase
in radiation striking the image receptor. In the event of
significant overexposure, the result is the radiologist’s
inability to see all anatomical structures normally visible in the image because of saturation. The saturation
can be seen regardless of image brightness and contrast
settings. It is up to the radiographer and radiologist to
determine whether an underexposed or overexposed
image is of diagnostic quality.
Exposure Indicator
Digital systems lack the visual cues that lead to the
recognition of exposure errors when working with filmscreen imaging systems. As a result, the radiographer
needs to monitor the exposure indicator (EI) associated
with the digital imaging system. Monitoring the EI for
each image helps to track and eliminate trends that can
lead to dose creep. Radiographers should assess EIs as
part of image critique, keeping in mind the variability
among vendors and the limitations of the EI.
Exposure indicators have been developed by most
equipment manufacturers. The purpose of the EI is to
allow the radiographer to assess the level of exposure
the receptor has received and thereby determine if the
correct exposure technique for the image was used.
At the present time, the name of the EI varies widely
among manufacturers. In addition to the variations in
name between manufacturers, the relationship between
a change in the level of exposure and the corresponding

Best Practices in Digital Radiography

change in EI is anything but uniform among manufacturers. The lack of a standardized name and response
relationship between dose and exposure indicator creates confusion for radiographers who work with equipment from multiple manufacturers, or of different ages
from the same manufacturer. It is critical to note that
EIs are not measures of radiation dose to the patient
and reiterate that EI records the level of exposure to the
image receptor.
The vendor community has responded, and by
a joint effort of the International Electrotechnical
Commission, the Medical Imaging and Technology
Alliance (MITA) and the American Association of
Physicists in Medicine (AAPM), manufacturers are
implementing an international standard for EIs called
IEC 62494-1. The IEC standard provides common
EI values for use with all types of digital image receptors. The standard EI values do not provide an actual
patient dose, but instead provide an estimated value of
the incident radiation exposure to the detector for each
acquired image.
In 2009, the AAPM published AAPM Report 116:
An Exposure Indicator for Digital Radiography. The
report contains multiple recommendations regarding
the standardization of an exposure indicator. The recommendations of greatest significance to the radiographer are the use of consistent terminology among manufacturers; a uniform response relationship between
receptor exposure and exposure indicator; identification of target exposure values for examinations and a
clinically relevant exposure level indicator. Another of
the many recommendations contained in the report is
that each technologist workstation include a prominent
display of the DI following each image.
The deviation index (DI) is an important term to
recognize and understand. The deviation index is
based upon the established target exposure index values for the examination. The purpose of the deviation
index is to provide the radiographer with feedback
related to the level of exposure used to create the
image and to aid in determining whether corrective
action is required.
As a best practice in digital radiography,
radiographers must become familiar with the
specific EI standards for their equipment, and with
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the newer standardized EI and DI as they become
available in new and upgraded equipment used for
digital radiography.
Exposure Indicator Limitations
It is important to remember that currently the EI is
an indication of incident exposure at the image receptor
and not the radiation dose to the patient. A radiographer must understand the exposure technique factors
that lead to the EI value. During the processing of the
image data, a portion of the sequence involves the
identification of exposure field borders. Errors during
exposure field recognition can cause inaccurate standard deviation readings, and causes of exposure field
recognition errors vary among vendors.
Other limitations are the varying methods that
manufacturers use to determine relevant image regions
to analyze when generating EI values. Further, the
wide exposure range afforded by digital imaging and
issues such as poor collimation, patient positioning or
a patient’s unusual body habitus can cause EIs to be
higher or lower than expected. Completing an examination with an acceptable EI should not automatically
be accepted as verification of proper technique. A best
practice in digital radiography is the effective use of
the EI to determine whether adequate exposure has
reached the image receptor. The EI provides valuable
information about exposure to the image receptor,
and when evaluated along with image quality, assists
the radiographer in determining whether the digital
image meets departmental standards. Because the
EI has limitations, the radiographer must carefully
assess whether a repeat exam is necessary.
Artifact Analysis
Artifacts are unwanted densities in the image that
are not part of the patient’s anatomy and may negatively affect the diagnostic quality of the image. The
classification of artifacts with film-screen imaging are
based upon how and when the artifact is recorded on
the image. Radiographers are accustomed to identifying artifacts in film-screen radiographs, along with
their causes. Artifacts are classified according to cause:
exposure, processing and handling/storage. Artifacts
on digital images also can be classified into exposure,

Best Practices in Digital Radiography

processing and handling/storage. Regardless of the
acquisition method, radiographers should determine
the cause of any artifact on a digital image and report it
according to departmental policy.
Storage Phosphor Artifacts
Storage phosphor based image receptors used in CR
may be cassette-based or cassette-less. Because of the
manner in which the image data is captured and subsequently processed, storage phosphor based receptors
present artifacts that are unique to their design. The
phosphor plate may be the source of the artifact. Dust,
stains, cracks and scratches are some of the causes of
artifacts in the image. Identifying plate artifacts is a
straightforward process because the artifact only occurs
with one particular plate. Removing the damaged
plate or cleaning the dirty plate corrects the problem.
Cleaning of the phosphor plate should be done in accordance with the manufacturer’s directions.
When artifacts occur routinely across multiple examinations, they most likely are caused by problems that
occur during the reading of the plate. A description of
the components of the plate reader is beyond the scope
of this paper. However, a few key components that often
are involved with artifacts that occur at the time of plate
processing are the light guide, mirror optics, laser system and plate transport mechanism. Determining the
source of a plate reader artifact can be challenging. The
artifact needs to be described in terms of its brightness,
size, shape and location on the image.
Another source of image artifacts that occur across
multiple examinations involves the electronic and software components associated with the image creation.
Identifying the specific source of this type of artifact is
particularly difficult because of the frequency of their
occurrence and the complexity of the electronic circuitry. The appearance of these types of artifacts also
should be described in terms of their brightness, size,
shape and location on the image.
Finally, some CR image artifacts are caused by problems with the hardcopy printer; these closely resemble
film-screen artifacts. Fog, pressure marks and static
electricity can appear on printed images. Image distortion, abnormal shading and uneven distribution of
line scans can occur when the printer’s film conveyor

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system malfunctions. Radiographers also can cause
artifacts on the printed CR image if they place singleemulsion film upside down in the printer.
Direct Digital Receptor Artifacts
The flat-panel TFT and CCD-based receptors are
highly integrated and use complex electronic systems.
The flat-panel TFT receptors may be cassette-based
or cassette-less. At the time of this writing, the CCDbased receptor is cassette-less. The appearance of
artifacts on these systems is described in terms of their
brightness, size, shape and location on the image. The
appearance of an artifact with direct digital systems can
be the loss of an individual pixel within the image or the
loss of rows or columns of pixels. In addition, system
calibration issues can affect the entire image, resulting
in an image that does not have the proper brightness
and gray scale. Correction of the artifacts associated
with direct digital systems may occur by using a built-in
calibration software or may require contacting service
personnel to repair the equipment.
Image Processing Software Artifacts
Digital systems have elaborate software that is used
to process the image data to produce a specific image
appearance. The radiographer’s selection of the processing menu (specific to the body part and examination)
is a critical step during the imaging process that helps
minimize the likelihood of image processing artifacts.
Each examination menu has associated computer
analysis codes that are specific to the examination and
designed to determine the image appearance.
On some systems, the processing menu also determines how the EI is calculated for that examination. It is
because of this specificity that the radiographer needs to
select the appropriate processing menu to avoid processing artifacts and miscalculation of EIs. The selection of
the processing menu affects the display qualities of the
image, and in some systems menu selection can affect
the spatial resolution of the image. The common display
qualities of the image that menu selection can control
are brightness, contrast, edge enhancement and equalization. The specifics of how each of these display characteristics is manipulated are beyond the scope of this
paper. In the circumstance that a selected processing

Best Practices in Digital Radiography

menu does not produce the desired image appearance,
the radiographer needs to determine whether how the
exam was performed caused the poor quality image or
whether the menu needs correction. The menu should
only be corrected by someone with a thorough understanding of image processing as it applies to the specific
piece of equipment. It is important to note that when
used inappropriately, edge enhancement and equalization can degrade the diagnostic quality of the image submitted to PACS and therefore potentially affect the final
image interpretation.
A best practice in digital radiography is to recognize image artifacts and prevent future artifacts from
occurring by properly maintaining or acquiring service for the digital radiography equipment. In addition, a best practice in digital radiography is selection
of the correct processing menu for an examination to
ensure image quality.
Medical-legal Considerations
The radiographer must review the image from a
medical-legal standpoint, taking into consideration
such indications as ensuring that lead markers were
used and are visible on the digital image, and that
patient name and date of exam are imbedded in the
image. All departments should have documented
policies and procedures regarding digital imaging.
Radiographers should adhere to these policies and
should document sound reasons for deviations from
these policies and procedures for a given examination. Radiographers must review the image not only
for adequate exposure technique and image quality
with radiation safety in mind, but also for medicallegal implications.

Following Examination Completion

It is helpful for radiographers to remember that
image acquisition, processing and display are separate
stages in digital imaging. As a result, images can be
evaluated and optimized throughout each stage. As a
best practice, however, radiographers should resist the
urge to modify image features after images have been
processed and displayed. There are steps radiographers should take after the examination is completed,
though, to ensure that data associated with the image

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(dose and demographics) are recorded and that the
final image is prepared for diagnostic interpretation.
Postprocessing
Digital imaging offers postprocessing capabilities
that are not possible with film-screen radiography.
Regardless, radiographers should perform postprocessing of digital images only if necessary. Any electronic
masking that the radiographer performs on the image
should take place only outside of the actual exposure
field, and not be confused with collimation during the
image acquisition stage.
The digital image has original, raw data that should
be kept intact. Postprocessing can change the original
raw data and the set point that establishes the levels of
gray scale assigned to the pixels. A change in the raw
data can cause loss of information and thereby affect
the viewing capabilities in the PACS where it will be
accessed by the radiologist or referring physician for
diagnosis. Therefore, radiographers should adjust
window level or width settings only if absolutely necessary. As described in the previous section on image
processing software artifacts, if radiographers find that
the processing menu chosen does not provide adequate
image quality, they should identify the cause of the
poor image quality and determine appropriate corrective action. The processing menus are designed to provide optimum image quality relative to the anatomical
part exposed to x-rays. If the processing menu consistently provides inadequate image quality, the radiographer should report the problem for adjustment.
Recording of Exposure and Dose Data
All EI and exposure technique information (such
as mAs and kVp) should be included with the digital
image. All exposure information should be displayed
for the radiographer upon image review, and should
be retained as part of digital imaging and communications in medicine (DICOM) information imbedded
in the DICOM header. In digital radiography systems
where the x-ray control panel is not connected to
the image receptor electronically, such as with many
cassette-based systems, the radiographer should record
the technical factor information in the electronic data
associated with the image.

Best Practices in Digital Radiography

It is best practice that all radiation exposure information be recorded without radiographer intervention to eliminate errors or incomplete records, and
international standards have been issued to ensure
this occurs. The standards may not apply, however,
to all types and brands of equipment, particularly
cassette-based systems. Radiology departments
should work closely with vendors and PACS administrators to determine how EIs and technique factors
can be recorded according to departmental policy and
attached to and transmitted with the image. Currently,
radiographers can add missing information only in
technologist notes.
Inclusion of exposure information on every final
digital radiograph will help radiographers to take note
of and use the information for refinement of exposure
technique selection. Inclusion of data related to technical factors on every final exam’s DICOM header
should ensure that the radiology department can
maintain quality and adherence to the ALARA concept. It is essential that EI values and exposure technique factors be recorded and tracked along with dose
information. It is a best practice in digital radiography to electronically record exposure technique, EI
and dose data with the radiographic image to allow
for assessment and refinement of technique selection practices.

Quality Assurance

The need for sound quality control (QC) practices
as part of a quality management program is important
in digital imaging. Radiographers are the operators
of complex imaging equipment and therefore are
the individuals who may first recognize equipment
malfunction. In addition, as with film-screen radiography, human error can occur with digital imaging,
and these errors must be acknowledged and corrected
to prevent trends that could jeopardize patient radiation safety. Even more important, problems that
occur in digital acquisition or processing equipment
tend to be systematic problems, which can affect the
quality of every image and the radiation exposure of
every patient until the problems are identified and
corrected. Acceptance testing, regular calibration
and proactive and consistent QC can prevent these

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systematic errors; repeat analyses can contribute to
overall department quality improvement.
Equipment Acceptance Testing and Calibration
Digital equipment is calibrated at the manufacturer’s site, but conditions change when the equipment
is installed on site. A sound QC program begins with
thorough and organized acceptance testing immediately following equipment installation and before
clinical use. The facility’s medical physicist should be
actively involved in the acceptance testing, following
the most current AAPM task force recommendations
for establishing standards of performance for digital
equipment. Initial testing and equipment calibration
often is followed by a period of observation while the
device undergoes routine use. Initial acceptance testing
and calibration also helps the physicist establish a baseline performance for the equipment and subsequent
QC testing, which should occur systematically to reestablish a baseline.
Systematic Quality Control
Generators and x-ray tubes generally remain the
same when converting to digital systems, but other
parts of digital systems are new to radiographers
and require updated QC policies and procedures.
Departments transitioning to digital may have to
revise their QC procedures to accommodate digital
imaging. Regular performance testing and calibration of equipment should be done in accordance with
equipment manufacturer specifications, industry standards and any applicable state and federal regulations.
ACR guidelines recommend that a medical physicist
assist in establishing the systematic QC program,
monitor results and assist with corrective actions. In
addition, radiographers must become familiar with
the performance operation of the equipment in an
effort to identify potential equipment malfunction and
report their concerns to the appropriate individuals.
The guidelines also recommend that an on-site
radiographer be responsible for conducting routine
QC noninvasive activities. Radiographers should perform daily and periodic checks of equipment that do
not require physicist involvement. For example, the
radiographer should inspect the digital system daily

Best Practices in Digital Radiography

for possible physical defects, perform weekly phantom
testing for image quality and artifacts, and inspect
and clean image receptors routinely. It may not be
possible to perform every QC test daily, but periodic
testing can identify potential equipment malfunction.
Examples follow below, but each department may
vary, depending on the established quality assurance
program, along with institutional, state and federal
regulations or accrediting standards.
Image Receptors
QC procedures on image receptors may vary
depending on the type of digital imaging equipment
and manufacturer. It is important for the radiographer
to follow the manufacturer’s recommendations and
recognize performance malfunctions. At a minimum,
radiographers should perform routine equipment selftests and calibration procedures where appropriate
or image a QC phantom to assess equipment performance on a regular basis. In addition, CR imaging
plates should be visually inspected for damage or artifacts and cleaned appropriately. Radiographers also
should perform secondary erasure of plates daily at the
start of their shifts to prevent exposure artifacts.
Display Monitor
Display monitor performance has taken on added
importance because digital images only are viewed
electronically for quality review and diagnostic interpretation. Though most QC activities for monitors
are not the responsibility of radiographers, it is helpful to understand the basics of monitor performance.
Radiologists’ display monitors used for interpretation
(primary) should be tested and monitored according
to specifications set forth by the manufacturers and
the ACR Quality Control Manual, along with applicable state and federal regulations. Devices degrade at
different rates, but generally should be tested at least
monthly, and more frequently as they become older.
There are more stringent guidelines in place for diagnostic monitors than for secondary display monitors,
which are found at the radiographer workstations. It
is important that monitors throughout a work area be
consistent in terms of spatial resolution, luminance
(the amount of light emitted) and contrast resolution.

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Radiographers should physically inspect their
digital workstation monitors daily. Physicists use
Society for Motion Picture and Television Engineers
(SMPTE) or AAPM test patterns as minimum QC
checks for display monitors as well. A QC test pattern
should be imaged and displayed to test normal operation and stored to compare results over time.
Repeat Analysis
A repeat analysis should be a component of any quality assurance program in radiology. The monitoring of
repeats allows for the assessment of overall image quality, modification of examination protocols, the need for
in-service education, and tracking of patient radiation
exposures. Radiographers need to accurately identify
and document the reason for a repeat image. Analysis of
the department’s repeat rate provides valuable information for process improvement and the overall performance of the radiology department, and helps minimize
patient radiation exposure.
It is a best practice in digital radiography to implement a comprehensive quality assurance program
that involves aspects of quality control and continuous quality improvement, including repeat analyses
that are specific to the digital imaging system.
Workplace Culture
When departments convert to digital environments, the effects are felt beyond the demands of
learning to operate new equipment. Digital imaging
affects workflow within and outside of the radiology department. Although numerous personnel
must adjust, the implementation of digital radiography affects radiographers more than any other staff
members. The electronic transmission of images
from radiographer to radiologist and other workflow
issues have significantly reduced the amount of direct
contact between the radiographer and the radiologist, thereby affecting their working relationship.
Radiographers have less opportunity to discuss image
quality or other issues with the radiologist. Only
teamwork and open efforts at communication can
ensure a smooth transition and an ongoing culture
of quality, safety and efficiency. It is up to radiographers to personally emphasize a culture of safety

Best Practices in Digital Radiography

and professionalism and to pursue open discussions
regarding digital radiography to learn from and support radiologists and other technologists.
Safety and Professionalism
Digital radiography is expected to improve workflow
and patient throughput. As a result, radiographers often
are expected to work faster or manage more patients. It
is critical that radiographers continue to adhere to protocols and retain their responsibilities for patients even
in this fast-paced environment. The potential for harm
in performing radiologic examinations is high. A culture of safety and professionalism emphasizes patient
safety and advocacy, and recognizes the radiographer’s
critical role as the professional who delivers radiation to patients. The American Registry of Radiologic
Technologists (ARRT) Code of Ethics and ASRT
Practice Standards for Medical Imaging and Radiation
Therapy both emphasize professionalism and radiographers’ participation in and adherence to patient safety
activities. The ASRT Practice Standards also emphasize
innovation and lifelong learning.
It is essential that radiographers continue to learn
in an industry with technological advancements as the
norm. Radiographers should learn from one another as
well as from vendors, supervisors, physicians and formal
education or continuing education programs. Most
of all, a culture of safety and professionalism recognizes improvement and modification of systems and
operations over punishment of individuals. Successful
safety cultures are proactive, working to prevent error
events. Prevention of errors requires transparent
reporting without fear of reprisal and with the intent
of continuous improvement. Thus, a strong teamwork
environment is imperative.
Promote Collaboration and Radiation Safety in the
Workplace
The culture of safety and improvement must take
place within a fluid workforce. This can be positive
if members approach it professionally and as a team.
For example, ARRT data show that by 2015, the age
of radiologic technologists in the workplace will “balance,” and workers from the baby boom, generation
X and generation Y demographics will each make up

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about one-third of the workforce. In a 2011 ASRT
workplace survey of hospital-based radiologic technologists, 11 percent of registered radiologic technologists said they had left the radiologic sciences field.
Of those 11 percent, nearly 26 percent said they left
because they retired.
Most recent graduates have been educated using
digital radiography, and can contribute to the understanding of practicing radiographers regarding the
technology and workflow. To do so, however, experienced radiographers must be open to the recent graduates’ input. On the other hand, recent graduates must
appreciate and respect the backgrounds and practical
knowledge of experienced technologists.
Donnelly et al implemented a comprehensive
approach to patient safety in a radiology department
that included teamwork with other hospital departments, addressing staffing, opening communication
and feedback mechanisms, teamwork, nonpunitive
error responses and support from supervisors and
hospital management for patient safety. The number
of days between serious safety events increased nearly
fourfold. Emphasizing teamwork and implementing
formal safety programs can shift the culture toward
one focused on overall patient safety instead of simply
reporting errors or concerns about exposure alone.
A best practice in digital radiography is the development of a collaborative and supportive work team
in which team members learn from one another and
practice radiography safely and ethically.

The ASRT Practice Standards state that radiographers should be educationally prepared and clinically
competent to perform their jobs. Education and clinical
preparation include being prepared to perform digital
examinations should their departments use the technology. Managers should support these efforts, but it
is the responsibility of radiographers to take advantage
of the literature, seminars and other educational tools
available to them to become clinically competent. The
radiographer must retain all skills necessary for performing examinations and work cooperatively with
radiologists to reduce radiation exposure.
The variation in vendor-specific features necessitates
thorough and ongoing applications training for digital
equipment. Radiology departments and radiographers
should be proactive in seeking help from vendors, particularly during equipment installations and upgrades to
provide appropriate training; however, vendors also must
ensure that their applications specialists and support personnel are continuously trained and updated on changes
to technology. Vendors and radiology department managers must work together to determine training expectations in advance, which includes preassessment and
postassessment of trainees’ skills and time expectations.
Once applications trainers arrive on site, managers must
support radiographers’ attendance at training, and trainees must remain engaged throughout training completion. It also is essential that all members of the digital
imaging team, including service engineers, have training
and updated competencies in radiation protection.

Applications Training and Support

Review of Best Practices

The ACR guideline for digital imaging recommends
that radiographers performing digital examinations be
trained to properly operate the systems they routinely
use. The training should include image acquisition
technology, image processing protocols, proper selection of protocol options for specific examinations,
image review, EIs and radiation safety during procedures. Though it is appropriate for radiographers and
their supervisors to rely on applications training to supply equipment-specific training in these skills, it is the
responsibility of the radiographer to have base knowledge regarding digital radiography while using radiation
exposure techniques and ALARA principles designed
to minimize patient radiation exposure.
Best Practices in Digital Radiography

The following best practices for digital radiography
have been identified in this paper. This is not an allinclusive list but one that highlights the actions most
pertinent to digital radiography, radiation safety and
ethical practice.
It is best practice to:
 Select the appropriate exposure technique factors
for the patient’s size and condition, based on a
planned exposure system, designed in collaboration with radiologists, to determine adequate
image quality for diagnosis.
 Consistently include information regarding
the image receptor exposure in the image data
provided throughout the image archiving process.
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 Carefully review the examination ordered to
prevent potential duplication and to ensure
appropriateness as related to the patient’s history. If there is a possibility that the examination
might be inappropriate, the radiographer then
should consult with the radiologist and/or ordering physician to ensure the appropriate examination is being obtained.
 Follow the protocols and standards set by
the department and actively participate in
establishing and further developing protocols
that ensure consistency of diagnostic-quality
images and improved practices to reduce patient
radiation dose. This is a critical best practice in
digital radiography.
 Screen patients for potential pregnancy.
 Use the highest kVp within the optimal range
for the position and part coupled with the lowest
amount of mAs as needed to provide an adequate
exposure to the image receptor.
 Use automatic exposure control (AEC) when
indicated and use AEC that has been calibrated to
the type of image receptor to provide a consistent
exposure to the image receptor.
 Use exposure technique charts that are continuously improved and applicable to a wide range of
patient ages and sizes.
 Collimate the x-ray beam to the anatomic area
appropriate for the procedure.
 Apply electronic masking in a manner that demonstrates the actual exposure field edge to document appropriate collimation.
 Electronic masking must not be applied over
anatomy that was contained in the exposure field
at the time of image acquisition.
 Use lead shielding for anatomic parts that are
adjacent to the x-ray field.
 Consistently use lead anatomic side markers
captured on the original image during the x-ray
exposure.
 Use a grid with specifications recommended by
the digital imaging equipment vendor, generally
for body parts that exceed 10 cm.
 Use immobilization devices when needed and
prevent repeat exposures by appropriately positioning the patient.
Best Practices in Digital Radiography

 Take appropriate actions to follow ALARA principles, radiation protection, proper positioning,
immobilization and size-appropriate exposure
techniques in pediatric digital radiography.
 Become familiar with the specific exposure indicator standards for equipment and with the standardized EI as it becomes available in new and
upgraded equipment used for digital radiography.
 Effectively use the EI and deviation index to
determine whether adequate exposure has
reached the image receptor.
 Evaluate EI values, along with image quality
to determine whether the digital image meets
departmental standards.
 Recognize that because the EI has limitations
and other variables can affect the value, carefully
assess whether a repeat examination is necessary.
 Recognize image artifacts and prevent future
artifacts from occurring by properly maintaining
or acquiring service for the digital radiography
equipment.
 Select the correct processing menu for an examination to ensure image quality.
 Electronically record exposure techniques, EI
and dose data with the radiographic image to
allow for assessment and refinement of technique
selection practices.
 Implement a comprehensive quality assurance
program that involves aspects of quality control
and continuous quality improvement, including
repeat analyses that are specific to the digital
imaging system.
 Develop a collaborative and supportive work team
in which team members learn from one another
and practice radiography safely and ethically.

Recommendations

This committee makes several recommendations
for the future of digital radiography based on best practices to help ensure continued quality and improved
patient safety:
 Industry societies and vendors must continue
to work together to improve standardization
of exposure indicator values. This includes
consistency in exposure indicators and standard
deviation indexes.
20

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 Equipment manufacturers should provide
radiographers access to EI and DI information
clearly displayed on each image when viewed and
retained as part of the PACS DICOM headers to
ensure accurate exposures and data recording.
 At the institutional level, all radiology departments should develop and post exposure technique charts with radiologist and radiologic technologist involvement; the charts must identify
acceptable exposure indicator ranges.
 Members of the radiology team must collaborate
to promote patient radiation safety. This includes
medical physicists, radiologists, radiologic technologists and radiographers just graduating from
programs who have a more formal education
involving digital imaging skills.
 Radiographers, equipment manufacturers and
physicists should investigate and perform research
into grid construction as appropriate for digital
imaging.
 Radiographers, equipment manufacturers and
physicists should investigate and perform research
to further investigate kVp effects on patient dose
and the use of 15 percent increases (the 15 percent rule) in digital radiography image receptor
systems.
 Ensure that managers, radiologic technologists
and applications trainers collaborate to prepare
for applications training and base knowledge
before training begins on digital equipment.
 Institutions that care for children must develop
radiologic and digital imaging equipment protocols for pediatric radiography.

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Glossary

Bit depth. The number of bits, or binary digits, per
pixel. They encode the signal intensity (gray scale) of
each pixel for the digital image.
Collective dose. A measure of the total amount of
effective dose multiplied by the size of the exposed
population. Usually measured in units of person-rem or
person-sievert, or man-rem or man-sievert.

effective dose totals the absorbed dose to tissues and
the weighting factors that apply to particular tissues or
organs being irradiated.
Exposure indicator (EI). A quantitative method,
expressed as an EI value, to estimate the incident radiation exposure required to acquire a diagnostic-quality
radiograph. The EI is called by many other names,
depending on the vendor.

Computed radiography (CR). The imaging system,
most often cassette-based, that requires the cassette to
be manually inserted into a plate reader. CR uses photostimulable phosphor technology to capture images
that are then scanned by a laser to release the energy
absorbed, which is then to produce digital data that are
converted to an image.

Gray scale. The different shades of gray that a computer system can store and display in relation to the
number of bits the system uses to digitize images.

Contrast resolution: also known as gray-scale resolution. This is a digital system’s ability to display objects
at different signal (x-ray) intensities so that they can be
easily distinguished.

Pixel. A picture element, or the smallest component
of a digital image and piece of information that a digital
monitor can display. Pixels are represented by numerical codes.

DICOM. Digital Imaging and Communications in
Medicine. DICOM is a standard developed to interconnect medical digital imaging devices. The standard is
sponsored by the ACR and NEMA and aims to have
both a standard image file format and a standard communications protocol.

Spatial resolution. Spatial resolution is the ability to
differentiate between small and adjacent objects. It is
measured in line pairs per millimeter (lp/mm).

Digital radiography. Any form of radiography in
which the acquisition and display of the image are electronic in nature; the imaging system may be cassettebased or cassette-less This may include CR or DR as
defined in this glossary.

Luminance. The measure that describes the amount
of light that passes through or is emitted from a surface.
In DR, this is the display monitor.

Standard deviation index (DI). An index that provides feedback based on signal-to-noise ratio and the
target index value for each digital examination. The
purpose of the index is to help radiographers know
if the technique they used for a specific examination
was appropriate for optimal display of the anatomy of
interest.

Direct digital radiography (DR). The imaging system may be cassette-based or cassette-less. DR may use
a flat- panel with thin-film transistor or a charge-coupled device. The image reading process occurs immediately after the termination of the exposure and does not
require the radiographer to initiate the reading process.
Effective dose. Effective dose is the quantity that
relates more closely to stochastic radiation risk. The

Best Practices in Digital Radiography

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Exposure Indicators

Exposure indicators (EIs) vary among manufacturers, and even have different names, symbols and units. This chart
shows a list of select manufacturers and details regarding their EIs as of 2011.

Manufacturer

EI Name

EI Symbol

Units

Exposure Dependence

Detector Calibration
Conditions

Agfa

Log of median of
histogram

1gM

Bels

1gM + 0.3 = 2X

400 speed class, 75 kVp + 1.5
mm Cu; 1gN = 1.96 @ 2.5 µGy

Alara CR

Exposure indicator
value

EIV

Mbels

EIV + 300 = 2X

1 mR @ RQA5, 70 kV, +21 mm
A1 => EIV=2000

Canon

Reached exposure
value

REX

Unitless

for brightess=c1, contrast=c2,
1
REX α X (mR)

brightness = 16, contrast = 10,
1
1 mR = 106

Canon

EXP

Unitless

EXP = X

80 kVp, 26 mm
A1, HVL=8.2 mm
A1, DFEI=1.5

Carestream
(formerly Kodak)

Exposure index

Mbels

EI + 300=2X

80 kVp. 1. 0 mm
A1 + 0.5 mm Cu; EI=2000 @
1mR

Fujifilm

S value

Unitless

200/S X (mR)

80 kVp, 3 mm
A1 “total filtration”
S=200 @ 1 mR

Uncompensated
detector exposure

UDExp

µGy air
kerma

UDExp α X (µ Gy)

80 kVp, standard filtration, no
grid

Compensated
detector exposure

CDExp

µGy air
kerma

CDExp α X (µ Gy)

kVp, grid, and additional filter
compensation

Detector exposure
index

DEI

Unitless

DEI≈ratio of actual exposure
to expected exposure scaled
by technique, system parameters. Expected exposure can
be edited by user.

Not available.

Konica

Sensitivity number

Unitless

for QR=k, 200/S α X(mR)

For QR=200, 80 kVp, S=200 @
1 mR

Philips

Exposure index

Unitless

1000/X (µ Gy)

RQA5, 70 kV + 0.6 mm Cu,
HVL=7.1 mm A1

Siemens

Exposure index

µ Gy air
kerma

X(µ Gy)=EI/100

RQA5, 70 kV+0.6 mm Cu,
HVL=6.8 mm A1

Best Practices in Digital Radiography

WHITE PAPER

Task Force Members
 Tracy Herrmann, M.Ed, R.T.(R), University of Cincinnati, Blue Ash College, Professor and Radiologic
Technology Program Director
 Terri L. Fauber, Ed.D., R.T.(R)(M), Virginia Commonwealth University, Radiography Program Director
 Julie Gill, Ph.D., R.T.(R)(QM), University of Cincinnati, Blue Ash College, Chairperson and Associate
Professor, Allied Health
 Colleen Hoffman, R.T.(R)(M)(CT), Atlantic Medical Imaging, PACS Administrator
 Denise Orth, M.S., R.T.(R)(M), Fort Hays State University, Assistant Professor/Clinical Coordinator
 Paulette Peterson, M.Ed, R.T.(R)(M)(QM), Monroe Community College, Associate Professor/Clinical
Coordinator
 Randy Prouty, B.S., R.T.(R), Regional West Medical Center, Diagnostic Supervisor
 Andrew Woodward, M.A., R.T.(R)(CT)(QM), The University of North Carolina at Chapel Hill, Assistant
Professor

Best Practices in Digital Radiography

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Creator                         : Adobe InDesign CC 2014 (Macintosh)

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Best Practices In Digital Radiography Asrt12 Bstpracdigradwhp

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