[ RadSafe ] NCRP report: CT drives massive increase in medicalradiation dose
Ludwig E. Feinendegen
feinendegen at gmx.net
Wed Mar 4 02:54:48 CST 2009
Thanks very much for sending the AuntMinnie report on the recent NCRP
assessment on US population exposure, mainly from medical applications,
----- Original Message -----
From: "ROY HERREN" <royherren2005 at yahoo.com>
To: <radsafe at radlab.nl>
Sent: Wednesday, March 04, 2009 2:43 AM
Subject: [ RadSafe ] NCRP report: CT drives massive increase in
> NCRP report: CT drives massive increase in medical radiation dose
> By Eric Barnes
> AuntMinnie.com staff writer
> March 3, 2009
> The U.S. population's exposure to ionizing radiation from medical
> procedures grew more than sevenfold between the early 1980s and 2006 -- an
> increase largely attributable to spectacular growth in the use of CT,
> according to a new report released today by the National Council on
> Radiation Protection and Measurements (NCRP) of Bethesda, MD.
> The increase in radiation exposure was due mostly to the higher
> utilization of CT and nuclear medicine, said Kenneth Kase, Ph.D., NCRP
> senior vice president and chair of the committee that produced the report,
> which was released in conjunction with the NCRP's annual meeting on March
> 2 and 3 in Bethesda.
> "These two imaging modalities alone contributed 36% of the total radiation
> exposure and 75% of the medical radiation exposure of the U.S.
> population," Kase said in a statement accompanying the report's release.
> The report found that in 2006 the U.S. population of 300 million
> individuals received a collective effective dose from medical radiation of
> 899,000 person-Sv and an effective dose per individual of 3 mSv. That
> compares to a collective effective dose of 123,700 mSv and an effective
> dose per individual of 0.53 mSv in the early 1980s.
> The number of CT scans and nuclear medicine procedures performed in the
> U.S. during 2006 was estimated to be 67 million and 18 million,
> respectively. In contrast, only an estimated 18.3 million CT exams were
> conducted in the U.S. in 1983, the report stated.
> The 2006 results show a marked increase (by a factor of 7.3) in the
> collective effective dose over 25 years, with a corresponding 5.7
> effective dose increase per individual in the U.S. population, the authors
> wrote. (The report did not include dose from radiation therapy and other
> specialized imaging procedures -- see chart below.)
> The following chart shows the annual effective dose per individual for a
> variety of medical imaging procedures from the early 1980s to 2006:
> Procedure Effective dose per individual -- 1980s (mSv) Effective dose per
> individual -- 2006 (mSv)
> CT 0.016 1.47
> Radiography and fluoroscopy 0.36 0.33
> Interventional fluoroscopy 0.018 0.43
> Nuclear medicine 0.14 0.77
> Total 0.53 3.00
> Data does not include radiation dose from radiation therapy, PET/CT,
> SPECT/CT, CT/fluoroscopy, and interventional applications. Data from the
> National Council on Radiation Protection and Measurements, "Ionizing
> Radiation Exposure of the Population of the United States," March 3, 2009,
> table 4.19.
> Background radiation accounted for 3.1 mSv of effective dose per
> individual in 2006, compared to 3.0 mSv in the early 1980s, the report
> Medical sources of radiation in 2006 resulted from:
> * CT - 49%
> * Nuclear medicine - 26%
> * Interventional fluoroscopy - 14%
> * Conventional radiography and fluoroscopy - 11%
> CT dose booms
> The report blamed skyrocketing CT use as the main factor contributing to
> rising individual dose.
> "Technological advances in CT and the ease of use of this technology have
> led to many clinical applications that have increased the use of CT at a
> rate of 8% to 15% per year for the last seven to 10 years," they wrote.
> The report cites data from market research firm IMV Medical Information
> Division of Des Plaines, IL, indicating that the number of MDCT scanners
> in the U.S. increased from nearly 51% of total scanners in 2004 to 71% in
> In 2006, the average CT exposures, taken from medical literature, included
> the following:
> CT procedure Range for effective dose (mSv) Effective dose (per scan) used
> in calculation (mSv)
> Head 0.9-4 2
> Chest 4-18 7
> Abdomen and pelvis 3-25 10
> Extremity 0.1-10 0.1
> Virtual colonoscopy 5-15 10
> Whole-body screening 5-15 10
> Calcium scoring 1-12 2
> Angiography: head 1-10 5
> Angiography: heart 5-32 20
> Other scans 1-10 5
> Data from the National Council on Radiation Protection and Measurements,
> "Ionizing Radiation Exposure of the Population of the United States,"
> March 3, 2009, table 4.2.
> "While the greatest growth in the number of CT procedures occurred in the
> late 1990s and early 2000s, the use of CT technology in the U.S. is likely
> to continue to increase over the next 10 years," the report stated. "Many
> new clinical applications are being developed; CT technology can be used
> with ease, perform a patient scan in a very short time ... and provide
> high-quality images for diagnosis."
> While conventional radiography and fluoroscopy comprise the largest number
> of exams in the U.S., the collective effective dose from these exams
> represents only a small percentage (11%) of the total medical dose, the
> authors wrote. Migration to CT studies is responsible for a steady decline
> in the contribution of this category to total radiation dose.
> "Some particular radiographic examinations did increase, such as
> mammography, which was also just becoming accepted medical practice in
> 1980, and chest imaging, which as a screening tool for admissions may
> simply reflect an increase in the number of patients in the healthcare
> system," they wrote. "Thus, most of the increase in [individual exposure]
> for medical applications represents utilization of new tools since the
> assessment in NCRP."
> Cardiac imaging dominates nuclear medicine
> Between 1982 and 2006, the estimate of radiation to individuals in the
> U.S. from in vivo diagnostic nuclear medicine increased by 460%, and the
> collective effective dose increased by 620%, the authors noted. Between
> 1972 and 2006, diagnostic nuclear medicine procedures increased by a
> factor of 5.5, while the U.S. population increased by approximately 50%.
> And during the past decade, there was 5% annual growth in the number of
> nuclear medicine procedures, while the U.S. population grew less than 1%
> annually, the authors reported.
> "Nuclear medicine has grown steadily since the end of World War II. There
> has been continuing evolution of instrumentation, development of new
> radiopharmaceuticals, and competition with other imaging techniques," the
> authors wrote. In 2006, the annual number of nuclear medicine patient
> visits in 2005 was slightly more than 17.2 million, resulting in 19.7
> million procedures performed.
> Cardiac imaging alone accounted for 85.2% of all nuclear medicine
> radiation in 2005, whereas the next highest contender, bone imaging,
> contributed just 9.3% of the total radiation. Tumor imaging, at 1.8% of
> the total, was a distant third.
> For example, a cardiac perfusion study was estimated to deliver an
> approximate effective dose of 12.6 mSv with the use of a technetium-99m
> sestamibi radiopharmaceutical and 33 mSv with the use of thallium
> The report cited cardiac interventional procedures across modalities as
> another big source of ionizing radiation. "It is of interest to note that
> the cardiac procedures comprise only 28% of the total number of
> procedures, yet the collective effective dose is 53% of the total for all
> interventional procedures," they stated.
> Excluding nuclear cardiology, the number of nuclear medicine procedures
> increased only by approximately 1,000 procedures over 24 years, while the
> U.S. population grew by 30%, they said.
> ACR blames self-referral
> Weighing in on the report, the American College of Radiology (ACR) in
> Reston, VA, cautioned that medical imaging provides benefits that must be
> carefully weighed against the risks of intervention.
> "It is essential that this report not be interpreted solely as an increase
> in risk to the U.S. population without also carefully considering the
> tremendous and undeniable benefits of medical imaging. Patients must make
> these risk/benefit decisions regarding their imaging care based on all the
> facts available and in consultation with their doctors," said Dr. James
> Thrall, chair of the ACR board of chancellors.
> The ACR said the evidence shows that in-office imaging is responsible for
> significant unnecessary radiation exposure, and that new laws are needed
> to curb self-referral by nonradiologist providers who are too quick to
> image and too slow to adopt dose-reduction measures.
> Peer-reviewed studies "have shown that when physicians refer patients to
> facilities in which they have a financial interest, imaging utilization is
> significantly increased," the ACR wrote.
> Medicare data from 1998 to 2005 show that the number of self-referred,
> in-office CT, MRI, and nuclear medicine scans performed grew at triple the
> rate of the same exams performed in all settings, the ACR stated.
> "Private insurance studies indicate that as much as half of this
> self-referred imaging is unnecessary, in many instances needlessly
> exposing patients to radiation," the ACR wrote. "Provider fear of
> litigation, advancing technology, and patient demand may have also
> contributed to this increase in exposure."
> The organization advocates federal standards for in-office high-tech
> medical imaging providers or for imaging facilities not registered as
> independent diagnostic testing facilities. Most nonradiologist providers
> receive little, if any, radiation physics or imaging training.
> "Self-referral is a concern," NCRP executive director David Schauer,
> Sc.D., told AuntMinnie.com, citing a study that identified $16 billion
> wasted each year from self-referred imaging studies. Another study
> identified dose reductions of 44% when ACR appropriateness criteria were
> followed (Journal of the American College of Radiology, March 2004, Vol.
> 1:3, pp. 169-172; American Journal of Roentgenology, April 2006, Vol.
> 186:4, pp. 937-942).
> Radiologists are working to lower dose and to educate elected officials,
> government agency staff, and referring physicians of the need for further
> steps toward the goal of ALARA (as low as reasonably achievable) dose
> levels for medical imaging.
> The ACR cited a number of programs it has developed to counteract
> overimaging and overuse of radiation, including its imaging
> Appropriateness Criteria, a white paper on radiation dose in medicine, and
> other information available on the ACR Web site.
> Meanwhile, the Alliance for Radiation Safety in Pediatric Imaging offers
> information on the popular Image Gently campaign, which is designed to
> make providers aware of opportunities to lower the radiation dose used in
> the imaging of children and encompasses 34 medical organizations
> NCRP faults defensive medicine
> NCRP executive director Schauer told AuntMinnie.com that the role of
> so-called "defensive medicine" in excessive radiation exposure is every
> bit as important as the problem of self-referral by nonradiologists -- as
> evidenced in a 2008 survey study by the Massachusetts Medical Society (the
> full survey report is available on the society's Web site).
> "They asked physicians why they were ordering exams, and they concluded
> that a full one-third were ordered just because they didn't want to be
> sued," Schauer said.
> "When you talk about the philosophy of radiation protection, before you
> expose a person to ionizing radiation you must first justify its use by
> weighing the benefit to the patient with the risk," he said. Once you
> decide to perform an exam, the dose must be optimized to maximize the
> benefit and minimize the risk.
> Adherence to ACR guidelines, "evidence-based criteria that in effect you
> might call a standard of care," he said, is key to reducing radiation
> exposure. In doing so, "issues like self-referral and defensive medicine
> may be reduced -- this is our hope," Schauer said.
> The timing of the NCRP report is also interesting because the Obama
> administration wants to save money on healthcare -- and careful adherence
> to imaging standards will accomplish just that, Schauer added. The
> Massachusetts survey estimates a potential annual savings of $1.4 billion
> in that state alone.
> By Eric Barnes
> AuntMinnie.com staff writer
> March 3, 2009
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