Cristen Bolan, Editor, Applied Radiology; Roundtable participants: Dianna
M. E. Bardo, MD; George M. Ebert, MD, PhD; Johnsey Leef, MD; Claudio
Smuclovisky, MD; Richard Towbin, MD; Chip Truwit, MD; Michael
Vannier, MD; and Charles White, MD
This year, the
medical community has witnessed significant strides in computed
tomography (CT) imaging through the adoption of ground-breaking
iterative reconstruction (IR) techniques. Physicians are now able to
improve image quality and diagnostic confidence at low dose levels.
Adoption of these techniques, particularly iDose4 from
Philips Healthcare, has allowed clinicians to push the clinical
capabilities of their scanners in order to enter a new era in CT imaging
where outstanding image quality can be achieved with images scanned at
Bringing solutions to the table
In the second part of an Applied Radiology low-dose supplement series, the publishers at Applied Radiology
invited leading radiologists and nuclear medicine physicians to a
roundtable discussion to share their clinical experiences implementing
new IR technology on the latest generation of CT systems.
These doctors have been working with the Philips iDose4,
an IR technique that gives them control of the dial so they can
personalize image quality based on their patients’ needs at low dose.
When used in combination with the advanced technologies of the iCT,
Ingenuity, and Brilliance scanner families, this provides a unique
approach to managing important factors in patient care—a new era in
low-energy, low-dose and low-injected contrast imaging (Figure 1).
Striking a balance
don’t realize how much dose a patient is getting,” said Dianna M. E.
Bardo, MD, Associate Professor of Radiology and Cardiovascular Medicine,
and Director of Cardiac Radiology, at Oregon Health and Science
University, Portland, OR. “It really is a challenge to show that we are
actually able to do an adequate examination while still imaging ALARA.”
the inequality between dose management and image quality is balancing
out. Recently, a different approach to standard image reconstruction was
explored through the clinical implementation of IR techniques. IR
techniques treat noise at very low signal levels, and consequently
reduce the noise and artifacts present in the resulting reconstructed
image. The noise can also be controlled for high spatial resolution
reconstructions; thus providing low noise, high spatial resolution, and
low-contrast resolution within the same image. This results in an
overall image quality improvement at low dose.
techniques have been used for many years in PET and SPECT imaging, only
recently have innovations in computational hardware design and algorithm
optimizations permitted the clinical use of an IR technique in CT. In
fact, applying an IR technique in combination with the iCT system can
improve spatial resolution by up to 50% and by up to 57% with the
Ingenuity CT (Figure 2).
Every patient is unique
number of IR techniques are available, each with its own design. Among
the various designs, the resultant image quality and reconstruction time
may vary considerably. Although a hospital may have an IR technique
available on its CT system, if its reconstruction times are lengthy,
practitioners may avoid using the technique. “Everybody wants to see the
images immediately,” noted Johnsey Leef, MD, Chief of Radiology,
Charleston Area Medical Center (CAMC), Charleston, WV.
addition—because every patient is unique individual protocols should be
“right-sized” and adjusted according to a patient’s age, height, weight,
body mass index (BMI), and clinical indication. By taking a more
holistic approach with iDose4, reconstruction is achieved in seconds rather than minutes (Fig-ure 3).
lowering our mA across the board in pediatric patients, we really
improved our pediatric doses substantially,” said Dr. Bardo.
imaging benefits from faster acquisition times—such as those provided
by the Brilliance iCT—as pediatric patients have a tendency to move and
“In some cases, exam speed may eliminate the
need for sedation or for anesthesia, which is highly prevalent in the
pediatric population, particularly with children under the age of 6,”
indicated Richard Towbin, MD, Radiologist-in-Chief, Division Chief,
Neuroradiology, Radiology, Phoenix Children’s Medical Group, Phoenix,
Speed also supports other indications, particularly in patients with rapid heart rates.
indications for cardiac CT are different in children and adults. Since
the neonates have very fast heart rates, it’s a challenge to do certain
types of studies unless the scanner is very fast. Our challenge is to go
fast enough to get accurate anatomy to see abnormal connections between
chambers and the abnormal development of structures that comes along
with the congenital heart disease population (Figure 4),” explained Dr.
Towbin. He added that faster acquisition times has the potential reduce
the number of repeat images exams.
Dose management best practices
are many strategies for modifying CT protocols to reduce overall
effective dose. Automated exposure control, dynamic collimation, and
prospectively-gated cardiac imaging are technologies that facilitate
dose management; however, other techniques, such as decreasing the
number of scanning phases, increasing the section thickness, reducing
the peak tube voltage (kVp), reducing the tube current–time product
(mAs), and increasing the pitch, also help manage dose.
described how he is also managing dose levels in pulmonary embolism
(PE) exams. “Low dose really comes into play with pulmonary embolism
studies. If you can get away with a 100 kVp instead of the 120 kVp or
even the 140 kVp, that is going to really raise your attenuation,” he
“We are increasingly going to the 100 kVp, the low-energy approach.”
UVM College of Medicine, radiologists have been applying a variety of
dose management techniques, including lower energy (kVp), longitudinal
(Z-DOM) and rotational (D-DOM) tube-current modulation, and automatic
current selection to adapt to patient sizes.
Dr. Smuclovisky has
taken a similar approach in cardiac imaging. “We’ve been able to take
the large patients from 140 kVp to 120 kVp (Figure 5), the average size
patients from 120 kV to 100 kV and with a mAs in the range of <200 to
300 (Figure 6). And we’re getting excellent diagnostic quality images.
For cardiac CT, we’ve reduced the radiation dose from an average of 3.5
mSv to 2.5 mSv and less,” he said.
United front on dose management
the medical imaging community has long supported imaging with radiation
doses as low as reasonably achievable (ALARA), the government has
recently begun to play an increasing role in the practice of medical
imaging, particularly as it relates to the use of CT.
of California enacted a law (SB 1237) last October requiring
radiologists to record the radiation dose that each patient receives for
a CT scan, effective July 1, 2012. In addition, as of January 1, 2013,
the bill mandates accreditation by one of 3 professional groups for
scanners at every facility that performs CT.
dose continues to be the responsibility of those administering medical
imaging procedures—the doctors and technologists.
there had been no standardized method in the United States for tracking
levels of dose delivered in imaging procedures. Yet, according to the
literature, to accurately assess radiation risks and keep radiation
doses as low as reasonably achievable, radiologists must be
knowledgeable about the doses delivered during various types of CT
studies performed at their institutions.1
national benchmarks for CT dose, the American College of Radiology
(ACR) launched the National Radiology Data Registry, which includes the
Dose Index Registry (DIR). This data registry allows facilities to
compare their CT dose indices to regional and national values. The dose
indices for all CT exams are collected, anonymized, transmitted to the
ACR, and stored in a database. Institutions are then provided with
periodic reports comparing their results by anatomical region and exam
type to aggregate data.2
“The new ACR registry allows
imaging providers and the imaging community to measure the effectiveness
of dose reduction efforts over time. The imaging community is committed
to optimizing CT dose and ensuring that patients receive only the
amount necessary to get an effective medical image,” said Richard L.
Morin, PhD, Chair of the ACR Dose Index Registry. “The registry is a
significant new tool to ensure proper CT dose use and that patients
receive safe, quality imaging care moving forward.”3
the ACR has launched other dose reduction initiatives, such as
mandatory accreditation of all medical imaging providers and the
adoption of computerized decision support/imaging ordering systems based
on ACR Appropriateness Criteria®, the DIR represents a
landmark move that enables imaging facilities to track, compare, and
manage radiation dose from CT scans.
“Dose optimization is
paramount to the ACR and the larger imaging community. This registry is a
leap forward in the process of optimizing patient dose and the practice
of safe, quality imaging care for patients. We are proud to offer this
groundbreaking medical tool to the benefit of Americans and the American
healthcare system,” said Harvey L. Neiman, MD, ACR Chief Executive
The pediatric radiology community has been a
natural leader in the campaign to reduce dose exposure, which may pose a
greater health risk to the pediatric population than to adult patients.
One of the most successful programs spearheaded by pediatric
radiologists is the Image Gently campaign, an initiative to promote the
use of appropriate dose reduction techniques by raising awareness in the
medical imaging community about the opportunities to reduce radiation
in the imaging of children. The Image Gently campaign, which is
conducted by the Alliance for Radiation Safety in Pediatric Imaging, and
founded by the Society for Pediatric Radiology, the ACR, the American
Society of Radiologic Technologists, and the American Association of
Physicists in Medicine, now encompasses 44 medical organizations serving
more than 500,000 health care providers world-wide.
recent endeavor in pediatrics is the establishment of the first
pediatric Quality Improvement Registry in CT Scans in Children, marking
another milestone in monitoring and reducing dose. The concept of the
registry is to form a coalition of 6 children’s hospitals that will
develop a consensus for “best practices” of optimal CT scan techniques
and design a dose index based on patient size for children undergoing CT
scans for common medical indications.
“Through the use of
well-tracked data, this group will identify the current state of CT
practice at their own institution and within the coalition, promote
transparency of practice within the group through sharing of
de-identified data through the American College of Radiology National
Radiology Data Registry, create a process of continuous improvement,
enact change locally through the development of a quality team at each
site to standardize performance of the CT scans across the coalition.”4
strengthen the drive to provide safe, appropriate, and effective
medical imaging, physicians have gone a step further, reaching out to
manufacturers to help in implementing dose-management strategies
nationwide. Manufacturers have responded by setting equipment safety
standards, developing protocols, performing quality and safety checks,
providing education programs and physician-developed medical guidelines.
In February of 2010, the Medical Imaging & Technology
Alliance (MITA), introduced a radiation dose check feature that provides
an alert to CT machine operators when a facility’s pre-determined dose
threshold is exceeded.
The Alliance for Radiation Safety in
Pediatric Imaging applauded MITA’s initiative. “The safeguards proposed
by MITA represent a major step forward in managing radiation dose during
CT scans performed on children, who are much more sensitive to
radiation than adults,” said Marilyn Goske, MD, Chair of the Alliance
and Professor of Radiology at Cincinnati Children’s Hospital Medical
Center in Cincinnati, Ohio.
Nevertheless, dose management
presents a unique challenge in CT imaging. As dose is lowered, image
quality suffers. When image quality suffers, so does confidence in
diagnosis. Solutions to this dilemma are of vital importance to
Perhaps the two most significant contributions
from manufacturers thus far have been 1) the development of IR
techniques, which reduce the loss of image quality when imaging at very
low doses, and 2) the introduction of CT systems with fast image
New era of dose management
P. Drayer, MD, President of the Radiological Society of North America
(RSNA), recently called upon radiologists to champion the cause to lower
dose in the medical community as a whole, adding that radiologists
“play an essential part as champions for safe imaging.”
Smuclovisky sees radiologists as the champions of the cause to lower
dose, and encourages them to ally with industry to create awareness and
make a difference.
One such initiative is SMILE—Smart Medical
Imaging Less Exposure—a community health educational program introduced
by Philips Healthcare designed to help clinicians inform their patients
and community about the importance of medical imaging and the risks of
radiation dose. SMILE provides physicians with a variety of tools to
help them generate awareness for imaging services and communicate a
hospital’s commitment to radiation dose management.
supports programs like SMILE. “The goal of the SMILE Campaign is to
increase awareness about dose across the board. It’s critical for
patients to feel safe,” said Dr. Towbin, who stressed the importance of
explaining to patients that CT is an extremely useful tool and should
always be used with patient safety in mind. “It’s important for major
imaging vendors to take leadership and ownership to decrease dose. What
is first and foremost are patients,” he said.
It’s clear the
driving message of the imaging community—imaging ALARA—has been embraced
by practitioners and vendors alike.Now with effective tools at the
radiologists’ disposal, such as low-dose CT, the low-dose campaign has
turned a corner, entering a new era in CT imaging where quality imaging
and patient care go hand in hand.
Portal to the future
is also gaining huge efficiencies through new advances in image data
management systems that provide clinical functionality, workflow, and
For George M. Ebert, MD, PhD, Associate
Professor of Radiology, Chief, Informatics and Imaging Technology,
Co-Director of Clinical MRI, University of Vermont College of Medicine,
Burlington, VT, in affiliation with Fletcher Allen Healthcare, these
types of workflow solutions “open the door between radiology and the
clinical side of medicine.”
One such workflow platform is
IntelliSpace Portal by Philips Healthcare. “IntelliSpace Portal is
automated to the point where a brain perfusion study now requires almost
no input other than to turn on the product (Figure 7),” said Dr. Ebert.
This integrated clinical solution is a multispecialty, multimodality,
and multivendor platform with robust clinical applications in CT, MR and
PET/CT. It supports communication between radiologists and other types
of clinicians, who can access and exchange data from any location
connected to the enterprise through a single applications server
integrated with PACS. This is critical when triaging patients in the
emergency department, says Chip Truwit, MD, Professor and Chief of
Radiology, Hennepin County Medical Center and Hennepin Faculty
Associates Minneapolis, MN. By streamlining data exchange across
hospitals, patients are less likely to undergo repeat imaging exams,
which “makes a difference on the dose, and also makes a tremendous
difference on patient care,” noted Dr. Truwit.
At South Florida
Medical Imaging Cardiovascular Institute, IntelliSpace Portal has
enhanced the clinic’s enterprise-wide workflow. “The automation tools
are fantastic as well, creating all the vessels, and tracking
everything,” said Dr. Smuclovisky. “It has diminished reading time and
improved my workflow tremendously by having everything automated.”
Tamm EP, Rong XJ, Cody DD, et al. Quality initiatives: CT radiation
dose reduction: How to implement change without sacrificing diagnostic
Updated October 3, 2011. Accessed October 14, 2011.
Radiology Data Registry (NRDR). American College of Radiology.
Updated September 29, 2011. Accessed October 14, 2011.
Nation’s CT Manufacturers Unveil New Industry-Wide Medical Radiation
Patient Safety Features. MITA.
Updated February 25, 2010. Accessed October 14, 2011.
Gently™” Alliance to Educate Providers to “Child-Size” Radiation Dose
for Pediatric Imaging Care. American College of Radiology.
Accessed October 14, 2011.