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2
Background
T
his chapter contains background factual information, much of which
was distilled from remarks made by workshop committee members
and workshop presenters.
2.1 TRENDS IN DIAGNOSTIC IMAGING
Dr. Hedvig Hricak, workshop committee vice-chair and chairman,
Department of Radiology, Memorial Sloan-Kettering Cancer Center,
explained the workshop’s scope and discussed the current advances and
trends in diagnostic imaging.
Advances in medical imaging in the past few decades using procedures
such as computed tomography (CT), fluoroscopy, and nuclear medicine
imaging exams have dramatically improved health care. Tissues deep within
the body can be easily accessed using these procedures, permitting radiolo-
gists to make diagnoses that previously would have necessitated exploratory
surgery (Wittenberg et al., 1978). Other direct benefits of modern imaging
procedures include more effective surgical treatment (Godoy et al., 2011),
potentially shorter hospital stays (Batlle et al., 2010), safer discharge of
patients (Litt et al., 2012), better diagnosis and treatment of cancer (Wagner
and Conti, 1991), more efficient treatment after injury (Philipp et al., 2003),
better treatment of stroke and cardiac conditions (Saini and Butcher, 2009;
Winchester et al., 2010), and rapid diagnosis of life-threatening vascular
conditions (Furukawa et al., 2009). Today in the United States, medical
5
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6 TRACKING RADIATION EXPOSURE
imaging occurs in hospitals and imaging centers, as well as free-standing
private physician, dental, and chiropractor practices.
A report released in early 2009 by the National Council on Radiation
Protection and Measurements (NCRP)1 titled Ionizing Radiation Exposure
of the Population of the United States indicated that in 2006 Americans
were exposed to more than six times as much ionizing radiation from medi-
cal diagnostic procedures than in 1980 (NCRP, 2009). The average effective
radiation dose2 to which the U.S. population is now exposed is estimated
to be 3 mSv,3 which is comparable to the annual exposure from natural
background radiation which has remained unchanged for the past 20 years.
The most significant changes in medical diagnostic imaging were attrib-
uted to rapid increases in usage of higher-dose procedures particularly CT
and nuclear medicine (especially nuclear cardiology [Mettler, 2009]). Close
to 82 million CT exams are now performed annually in the United States
(IMV, 2011), up from 46 million in 2000 and 13 million in 1990 (Brenner
and Hall, 2007). Cardiac diagnostic nuclear procedures increased from 1
percent of the total number of diagnostic nuclear medicine examinations
performed in 1973 to 57 percent in 2005 (Mettler et al., 2009).
Many factors have been suggested as explanations for the sharp
increase in CT use (Baker et al., 2008; Iglehart, 2009), such as advances in
CT technology that have increased ease of use for physicians and comfort
for patients during testing; increased CT scanner availability; favorable
financial reimbursements for imaging procedures; and shifts in the practice
of medicine including more time constraints and promotion of defensive
medicine. Newer radiographic imaging modalities such as positron-emis-
sion tomography/CT (PET/CT), single-photon emission CT (SPECT/CT),
and potentially CT for screening of high-risk asymptomatic patients (for
example, smokers screened for early lung cancer detection) are likely to
further increase the population’s exposure (Brenner and Hricak, 2010).
1 The NCRP is a congressionally chartered organization that formulates and disseminates
information and research data related to radiation exposure and protection.
2 Effective dose is a dose parameter used to normalize partial-body radiation exposures
relative to whole-body exposures to facilitate radiation protection activities (ICRP, 1991).
Effective dose can also be used to enable comparison of risks between procedures that utilize
ionizing radiation. The International Commission on Radiological Protection (ICRP) does not
recommend use of effective dose for estimating population or individual risks. Effective dose
is expressed in sieverts (Sv).
3 The exposures of particular individuals could be higher or lower than these reported aver-
ages depending on how many medical imaging procedures that use ionizing radiation they
undergo. As discussed in Section 2.2, a number of individuals undergo multiple imaging exams
in their lifetime. Others may not undergo any. Therefore, their exposure would be higher or
lower than the estimated average.
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7
BACKGROUND
2.2 POTENTIAL HEALTH RISKS FROM DIAGNOSTIC IMAGING
Although the growing use of medical diagnostic procedures is corre-
lated with tremendous and undeniable benefits in care of most patients, it
comes with growing concerns about risks associated with the use of ionizing
radiation. A 2001 article in USA Today generated visibility and publicity
and became a critical component in changing the prioritization of image
quality alone to image quality balanced with radiation dose in both adults
and children (Sternberg, 2001). Dr. David Brenner (Columbia University)
noted that ionizing radiation is an initiator and promoter of carcinogenesis.
In the absence of sufficient empirical knowledge regarding radiation effects
at low doses4 typically encountered in medical diagnostic procedures, it
is assumed that the probabilistic (stochastic) risk of cancer proceeds in a
linear fashion at lower doses without a threshold. Scientific groups such
as the International Commission on Radiological Protection (ICRP), the
United Nations Scientific Committee on the Effects of Atomic Radiation
(UNSCEAR), NCRP, and the National Research Council Committee on
the Biological Effects of Ionizing Radiation (BEIR), repeatedly review and
endorse the use of the linear-no-threshold (LNT) model for assessing risk
(NCRP, 1993; ICRP, 2005; NRC, 2006; UNSCEAR 2008). The LNT model
is often considered to be conservative and gives emphasis to public health
and is currently used to set radiation protection standards and operating
policies, such as the “as low as reasonably achievable” (ALARA) policy.
There is large scientific debate, however, on the nature of the shape of the
dose-response curve for radiation-induced cancers at low doses.
Assuming a linear relationship between dose and cancer risk at low
doses, a potential small increase in the chance of developing cancer is the
main health effect of concern associated with the use of medical diagnostic
procedures. The level of risk depends on the type of imaging procedure.
For example, the typical radiation exposure from a CT examination is
~100 times larger than that from an x-ray examination.5 The theoretical
individual risk of fatal cancer from a single CT for a dose of 10 mSv is
estimated to be around 1 in 2000 (Mettler et al., 2000).6 For comparison,
the natural occurrence of fatal cancer in the U.S. population is about 1 in 5.
When a diagnostic procedure is medically justified (e.g., in a symptom-
4 There is near-universal agreement that epidemiologic studies have demonstrated that radia-
tion doses above 100 mSv are associated with increased risk of developing cancer. However,
scientific debate on the potential cancer risks exists at low doses (< 100 mSv).
5 The average effective dose for a typical chest CT exam is 7 mSv and for a chest x-ray 0.1
mSv; an x-ray of the shoulder is around 0.01 mSv; the average effective dose for most nuclear
medicine procedures varies between 0.3 and 20 mSv (Mettler et al., 2008).
6 See also: http://www.fda.gov/radiationemittingproducts/radiationemittingproductsand
procedures/medicalimaging/medicalx-rays/ucm115329.htm.
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8 TRACKING RADIATION EXPOSURE
atic patient), it is apparent that the likely benefit to the patient is greater
than the risk, although the imaging exam should be optimized to the low-
est dose that provides acceptable diagnostic information (ICRP, 2008).
Special care is needed, however, for evaluating nonsymptomatic screening
protocols, such as for CT lung screening, where the estimated annual risk
from low-dose protocols is ~1.8 percent (upper limit is 5 percent) (Brenner,
2004) and the estimated benefit (measured as reduction in mortality from
lung cancer) among current or former heavy smokers is ~20 percent (NLST
Research Team et al., 2011). Because large numbers of individuals receive
radiation doses from medical imaging, whether for screening or diagnostic
purposes, the possibility exists that even small potential risks per individual
attributed to these exams could translate into many cases of cancer.
Not surprisingly, because CT is used to not only diagnose disease but
also follow the course of therapy and complications, a number of individu-
als have multiple CT scans in their lifetime. Wiest et al. (2002) reported
that in 2001 approximately 30 percent of their patients had more than three
CT exams in their medical histories, 7 percent had more than five, and 4
percent had more than nine. The percentages of repeated exams were higher
in a more recent study at one institution (33 percent of patients had 5 or
more lifetime CT exams and 5 percent had between 22 and 132) (Sodickson
et al., 2009). The patients who underwent large amounts of recurrent imag-
ing in the study generally had substantial underlying disease such as cancer
diagnosis (Sodickson et al., 2009). Irrespective of the presence or severity
of underlying disease, multiple CT scans of a patient can result in absorbed
doses that have been empirically shown to increase the risk of cancer. This
may be one of the reasons why for tracking radiation exposure from medi-
cal diagnostic procedures, CT scanning has received the majority of interest.
In contrast to the stochastic effects following radiation (e.g., develop-
ment of cancer and some cardiovascular diseases), accidental exposure
to very high levels of radiation can cause acute effects such as skin red-
dening, skin necrosis, hair loss, and severe tissue damage. These acute
effects are known as “deterministic” or “non- stochastic” radiation effects.
The problem of skin reactions following fluoroscopy were reported and
summarized by Shope (1996). Recently, several unfortunate and highly
publicized radiation overexposure events have been reported, especially
involving CT exams. In 2009 officials of the Cedars-Sinai Medical Center
in California notified the Food and Drug Administration (FDA) of acci-
dental overexposure of about 200 patients undergoing brain-perfusion CT
examination, resulting in hair loss and skin redness. The FDA identified
additional patients who received overexposures at other hospitals7 and
has subsequently issued advisory warnings to initiate preventive actions
7 See: http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm185898.htm.
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9
BACKGROUND
(Kuehn, 2010). These events have heightened the awareness of radiation
dose among radiologists, technologists, patient populations, regulators, and
international agencies.
Assuming compliance from both the medical provider and patient,
confirming and reporting the visible events of direct radiation injury may
be a relatively straightforward task. However, measuring the potential long-
term risks associated with low-level radiation doses from medical diagnostic
procedures is challenging and therefore the risks have not been fully quanti-
fied. This is because the number of excess cancer cases expected to result
from exposure to ionizing radiation from medical diagnostic procedures
is low and difficult to differentiate from background cancer rates, which
normally affect 42 out of every 100 persons.8 Studies to assess these small
risks would require very large numbers of individuals and long follow-up
periods (Land, 1980). Because any radiation-induced cancer would not
appear for years, it would be difficult, if not impossible, to relate it to past
imaging procedures. Results from large-scale epidemiologic studies assess-
ing the risks of medical diagnostic procedures that utilize ionizing radiation
are not available yet. However, a number of epidemiologic studies of risks
associated with CT exams are underway (see Section 3.5.1). CT exams are
likely the high-dose medical diagnostic imaging exams associated with the
easiest exposures and dose parameters to collect both in terms of equipment
output and in terms of estimation of actual patient doses.
An alternative to directly examining cancer occurrence or death from
cancer in the exposed populations is use of risk projection models. Such
models use population dose estimates and existing risk coefficients to
extrapolate the effects of medical diagnostic procedures. Typically popula-
tion risk estimates are derived from the atomic-bombing survivors cohort
in Hiroshima and Nagasaki; today, this cohort is widely considered the
“gold standard” in the assessment of radiation-induced cancer risks at low
doses.9 Medically exposed cohorts are also used to provide risk estimates
for risk projection studies.
The risks determined from projection models represent theoretical risks
rather than empirical observed risks and rely upon the assumption of a
linear relationship between radiation dose and risk at low doses. A study
with frequency data from Medicare claims and data from the IMV Medical
Information Division estimated that 29,000 future cancers could be related
to CT scan use in the United States in 2007 (Berrington de González et al.,
8 See: http://www.cancer.org/Cancer/CancerBasics/lifetime-probability-of-developing-or-
dying-from-cancer.
9 The effective dose from a typical CT exam is estimated to be about 8 mSv. This dose is
comparable to the lowest doses of 5 to 20 mSv received by some of the Japanese atomic-
bombing survivors.
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10 TRACKING RADIATION EXPOSURE
2009). Fifty-seven million CT scans were used for the calculation of the
potential future cancers. A second study showed that the lifetime cancer
risk estimates for standard cardiac scans varied widely depending on age
and gender, from 1 in about 3,000 for an 80-year-old man to 1 in about
140 for a 20-year-old woman (Einstein et al., 2007).
The risk estimates in the projection models used in the above-mentioned
studies deal with particularly challenging problems related to uncertainty
from various sources, in terms of both the dose for a given examination and
the cancer risk per unit dose in the estimations. Moreover, the magnitude
of cumulative individual doses from single or multiple procedures has not
been fully characterized because of limited medical recording and the lack
of sharing of medical information across different health care facilities.
2.3 APPROPRIATENESS OF DIAGNOSTIC IMAGING
The appropriateness of diagnostic imaging in terms of justification and
optimization were discussed by Dr. Donald (Don) Miller, acting chief, Diag-
nostic Devices Branch, Division of Mammography Quality and Radiation
Programs, Center for Devices and Radiological Health, FDA, and other
workshop participants.
There are two ways to reduce doses from diagnostic imaging: (1) do
imaging only when justified and appropriate and (2) for any given examina-
tion, use dose reducing approaches consistent with acceptable image quality
and diagnostic performance.
Although based on limited data, one in four procedures is believed to
be unjustified and therefore associated with unnecessary potential radia-
tion risk. Examples include unnecessary CT scanning of the chest both
with and without contrast or multi-phase scanning for patients undergoing
abdominal and pelvic CTs (Guite et al., 2011). It is estimated that each
year approximately 75,000 patients across the country have unnecessary
pre- and post-contrast chest CT scans (Bogdanich and McGinty, 2011). A
straw poll among pediatric radiologists indicated that about 30 percent of
CT examinations in children were unnecessary or could have been replaced
by imaging exams not using ionizing radiation such as ultrasound-based
imaging modalities (Berdon and Slovis, 2002). Although the outcome of
the straw poll does not constitute scientific evidence, it is an indicator that
the issue of unnecessary exams is recognized by the medical community.
Lack of training regarding clinical decisions is one cause of the use
of inappropriate examinations. In addition, ordering physicians may be
unaware that recommended criteria can guide them in particular clinical
decisions. Various professional organizations (e.g., the American College
of Radiology [ACR]) have produced evidence-based guidelines, but several
studies suggest that these guidelines have not been widely adopted by the
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11
BACKGROUND
medical community. In a retrospective study of 200 trauma patients, for
whom imaging decisions were made without the use of formal decision
rules, 169 of 200 patients underwent one or more CT scans, resulting in
an overall total of 660 CT scans. The authors found that application of the
ACR appropriateness criteria could have prevented 44 percent of those CT
scans from being ordered (Hadley et al., 2006). Other studies have found
that similar percentages (20-40 percent) of CT scans could be avoided by
following decision guidelines (Garcia Pena et al., 2004; Kuppermann et
al., 2009; Holmes et al., 2009; Stein et al., 2009). A pilot study showed
that two out of three nuclear cardiology scans performed were appropriate
according to the American College of Cardiology criteria, while the remain-
der were either inappropriate or of uncertain appropriateness (Hendel,
2009).
A successful approach to increasing the use of decision guidelines has
been to incorporate them into computerized imaging order entry systems
(Sistrom et al., 2009). However, even when decision guidelines are readily
accessible, a variety of factors may contribute to the ordering of unjustified
CT scans such as emergency department patient throughput, fear of liability
for a missed diagnosis, lack of information from other sources, and patient
and physician self-referrals (Dunnick et al., 2005).
2.4 REDUCTION IN RADIATION DOSES
Reducing the dose per exam is the second way to reduce unnecessary
exposure to radiation from medical diagnostic procedures, and this is dis-
cussed in the context of optimization10 and the need to create reference
values based on best practices (ICRP, 2008). Interest in this area has arisen
because wide variations have been observed among radiation doses associ-
ated with particular imaging exams both within and across medical centers.
Again, there is a specific interest in CT scanning, because of its amenability
to significant dose reductions (or increases) by the ease of manipulation of
technical factors during protocol adjustments.
One study in four San Francisco Bay Area institutions showed that
radiation doses varied significantly among different types of CT studies
performed on adult patients. A mean 13-fold variation between the highest
and lowest doses for routine head CT exams and multiphase abdomen and
pelvis CT exams was reported (Smith-Bindman et al., 2009). The authors
state that this observed variation cannot be entirely explained by differ-
ences in patient size (which were not accounted for in the analysis) or the
specifics of the clinical question that was being addressed. Large variability
10 Radiation dose is optimized when imaging is performed with as low as possible amount
of radiation required to provide adequate image quality for diagnosis or intervention.
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12 TRACKING RADIATION EXPOSURE
in doses was also observed in a recent multicenter study in France that
included children aged 0-5 years undergoing at least one CT scan between
2000 and 2006 (Bernier et al., 2012). In regard to nuclear medicine, a
survey of 13 pediatric hospitals in North America identified a broad range
of administered doses from institution to institution; these administered
doses would directly lead to variability in radiation-absorbed doses to the
pediatric patients (Treves et al., 2008).
Optimization of the techniques is viewed as a joint responsibility and
effort of the radiology facilities and equipment designers. For example,
manufacturers of CT scanners and fluoroscopy equipment have made many
successful attempts to reduce the doses associated with particular exam
types. These reductions have been accomplished through technological
advances in equipment design, implementation of features such as auto-
matic exposure control, and efforts to educate physicians and technologists
and create awareness of potential adverse radiation effects. A comprehen-
sive review of dose reduction efforts in nuclear medicine is presented else-
where (Hricak et al., 2011).
One of the earliest success stories of procedure optimization was an
effort to improve technical aspects of mammography, which culminated in
the passage of the Mammography Quality Standards Act in 1992 (Spelic et
al., 2007). This legislation set national standards for high-quality mammog-
raphy, including standards for mammographic x-ray equipment, patient
dose, and image quality and ensured that facilities in the United States
would meet those standards.
Radiologists attempt to reduce dose through use of optimized protocols
in accordance with national and international guidelines (ICRP 2000a,b,
2007a; McCollough, 2011). However, the information available to them
is frequently inadequate. For example, on the technical side, although new
CT and fluoroscopic devices include displays of dose metrics, some lack
other safeguards, such as default parameter settings that optimize radiation
dose or alerts when the radiation dose in a given exam exceeds a particular
reference level or range. Even when these safeguards are in place, users may
not have received adequate training in the proper use of these features and
the importance of optimizing radiation dose. Additionally, training often
takes place in the hospital or imaging center with all the concomitant dis-
tractions and without a verification of acquisition of knowledge at the end
of the training sessions (Slovis, 2002) or quality assurance practices within
the imaging facility.
On the dose side, Lee and colleagues (2004) performed a survey to
determine the awareness of emergency department physicians and radiolo-
gists of the radiation exposure from the CT scans that they order. About
75 percent of the entire group significantly underestimated the radiation
dose from a CT scan, and 53 percent of radiologists and 91 percent of
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13
BACKGROUND
emergency department physicians did not believe that CT scans increase
the lifetime risk of cancer. The risks and benefits of imaging procedures are
rarely communicated to patients (Lee et al., 2004) and are not recorded
in the patient’s medical record. In addition, many medical imaging devices
that communicate with radiology information systems do not forward data
on radiation dose despite recommendations to the contrary from the ACR
(Amis et al., 2007).
2.5 RECENT PROGRESS IN RADIATION SAFETY IN MEDICINE
A number of initiatives in radiation safety in medicine have taken place
in the United States and internationally and were discussed by the work-
shop invited speakers. Each of these initiatives serves different purposes.
The ultimate goal is to provide better quality clinical management of the
patient and to reduce dose by adhering to the ALARA principle, without
compromising diagnostic efficacy (ICRP, 2007b).
2.5.1 Image Gently and Step Lightly Campaigns
The Alliance for Radiation Safety in Pediatric Imaging11 launched the
Image Gently (in 2008) and Step Lightly (in 2009) campaigns aiming to
reduce unnecessary exposure to radiation during pediatric imaging and
interventional radiology, respectively. The campaigns’ goal is to promote
the special precautions required for children who undergo medical imag-
ing that utilizes ionizing radiation (Sidhu et al., 2009; Goske et al., 2010).
Through separate education material directed to patients, the health care
team (radiologists, technologists, and pediatricians), physicists, and the
news media, the Image Gently campaign has successfully disseminated its
message by partnering with prominent medical organizations and agencies.
2.5.2 Image Wisely Campaign
In 2010, the ACR and the Radiological Society of North America
(RSNA), together with the American Association of Physicists in Medi-
cine and the American Society of Radiologic Technologists, established
the Image Wisely campaign for minimizing radiation exposure in adults.
The campaign resembles but does not exactly mirror the Image Gently
campaign. The mission of the Image Wisely campaign is to raise aware-
ness of opportunities to eliminate unnecessary imaging examinations and
11 The Alliance for Radiation Safety in Pediatric Imaging is an organization of more than
60 national and international professional societies and agencies with the goal of promoting
radiation safety for children.
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14 TRACKING RADIATION EXPOSURE
to optimize the amount of radiation used in imaging examinations to only
what is necessary to acquire appropriate medical images. Image Wisely
has developed a web site with selected and logically indexed educational
material for imaging professionals, referring practitioners, and the public
and has partnered with imaging equipment vendors through the creation of
vendor-specific web pages to provide the most current information on dose
reduction techniques available on specific equipment. Participants in the
program are asked to demonstrate their commitment to the Image Wisely
principles by taking a pledge, pursuing accreditation, and participating in
national dose index registries (Brink and Amis, 2010).
2.5.3 ACR’s Dose Index Registry
The ACR launched the Dose Index Registry in May 2011 to address
the lack of a substantial database for determining the average dose indices
for a CT exam in the United States. Once these are determined, the data
can be used to establish national benchmarks and practice patterns in dose
indices and provide feedback to the participating facilities as to where they
stand compared to those benchmarks and how far they are from achiev-
ing optimal practices. The Dose Index Registry collects and compares CT
dose index information from facilities across the country and internation-
ally. Information is collected using automated standardized techniques and
includes exposure parameters (kVp, mAs) and dose indices (CT index vol-
ume [CTDIvol],12 dose length product [DLP]13). Currently the Dose Index
Registry does not collect information on dose estimates because they are
not available.
2.5.4 IAEA Smart Card
In 2006 the International Atomic Energy Agency (IAEA) initiated an
ambitious program named Smart Card with the purpose of tracking the
radiological procedures of individual patients and radiation dose. The pro-
gram, launched in 2009, will be implemented in some countries in three to
five years. Until the program was launched, the only way to track a patient’s
lifetime (cumulative) exposures was by manual search of physical or elec-
tronic records in a hospital or hospitals or reliance on the patient’s memory.
The Smart Card program emphasizes the need for a more systematic track-
ing method resulting from the substantial increase in the use of high-dose
radiation exams (Rehani and Frush, 2011). The major goals of tracking are
12 CTDI describes the amount of radiation that machines emit during one scan; that is, CTDI
is not the amount of radiation that enters the body.
13 DLP combines all the scans from an examination into one value.
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15
BACKGROUND
stated in the recent Joint Position Statement on patient exposure tracking14
and include: supporting accountability for patient safety, justification, and
optimization; providing information for assessment of radiation risks; and
establishing a tool for use in research and epidemiology.
The original name of the Smart Card program tended to give the
impression that the card would contain the patient’s estimated dose data;
thus, the name Smart Card/SmartRadTrack was subsequently adopted to
place the emphasis on tracking. The estimated patient doses are not avail-
able on the card. Instead, like an ATM card or a credit card, the card simply
provides the methodology (digital signature) to access dose information,
which is available online. The IAEA Smart Card/SmartRadTrack is con-
sidered to be an improvement over a more basic tracking approach such
as a vaccination card, which stays in the possession of the patient. Such a
method would rely fully upon compliance and maintenance by the patient
and may not have an impact on the quality of radiation dose management.
2.5.5 National Institutes of Health Clinical Center Initiative
The National Institutes of Health (NIH) Clinical Center has mandated
that imaging equipment manufacturers provide for electronic reporting
of patients’ radiation exposures from their equipment in this setting. The
information on radiation exposure reports will be logged into the patient’s
electronic medical record (EMR). Exposures from CT and PET/CT will be
the first to be recorded using this system, because CT and PET/CT scan-
ners already output this information (Neumann and Bluemke, 2010). The
goal of this policy within the NIH Clinical Center is to achieve an accurate
assessment of whether low-dose radiation exposure from medical imaging
exams increases the patient’s risk of developing cancer. It is understood
that steps taken within a single institution will not be sufficient to allow a
precise population-based assessment of cancer risk from lose-dose radiation
and that tracking of medical imaging doses from a truly large number of
individuals in the United States will ultimately be necessary. This initiative
is, however, necessary to begin building a prototypical data set (Neumann
and Bluemke, 2010).
Besides building a database for population-based risk assessment, the
NIH Clinical Center will require that vendors ensure that radiation expo-
14 The joint statement was endorsed by the World Health Organization, FDA, the European
Society of Radiology, the International Organization for Medical Physics, the International
Society of Radiographers and Radiological Technologists, and the Board of Directors of the
Conference of Radiation Control Program Directors. See: https://rpop.iaea.org/RPOP/RPoP/
Content/Documents/Whitepapers/iaea-smart-card-position-statement.pdf.
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16 TRACKING RADIATION EXPOSURE
sure can be tracked by patients via personal electronic health record plat-
forms such as Google Health and Microsoft HealthVault.
2.5.6 California Legislation
California became the first state in the United States to regulate CT
scans.15 The law dictates that facilities with CT systems capable of cal-
culating and displaying radiation dose index document the dose index of
each CT exam within the patient’s radiology exam report. (The deadline
for meeting the requirement is July 2012.) The law also requires that a
medical physicist verify annually the dose index for each protocol and that
any reported errors are communicated to patients and physicians. (The law
does not set a limit as to what the dose indices should be.) For the purposes
of this bill, the radiation dose that should be recorded is defined as any
metrics such as CTDIvol and DLP or a dose unit as recommended by the
American Association of Physicists in Medicine (AAPM).16 This legislation
was enacted in response to multiple events where patients were exposed to
excessive radiation by diagnostic CT scanners, with the intent to prevent
such events.17
15 Florida, New York, and Texas are also considering similar legislation (Schmidt, 2012).
16 AAPM is a member society concerned with the topics of medical physics, radiation oncol-
ogy, and imaging physics with a primary goal of identifying and implementing improvements
in patient safety for the medical use of radiation in imaging and radiation therapy.
17 See: http://www.leginfo.ca.gov/pub/09-10/bill/sen/sb_1201 1250/sb_1237_bill_20100929_
chaptered.html.
