Magnitude of Medical Radiation Exposures to US population
Mahadevappa Mahesh, MS, PhD, FAAPM.
Assistant Professor of Radiology & Cardiology
Chief Physicist - Johns Hopkins Hospital
The Russell H. Morgan Department of Radiology and
Radiological Science
Johns Hopkins University, Baltimore, MD
AAPM Annual Meeting, Houston, TX 2008
Outline
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Purpose and Goals of NCRP SC 6-2
Data Sources & Results*
How should regulatory agencies
react?
Discussions & Conclusions
NCRP Scientific Committee 6-2
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Kenneth R. Kase - Chairman
Subcommittees:
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Industrial Exposures
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Occupational exposures
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Medical Patient Exposures
NCRP SC 6-2: Purpose
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To update NCRP Report 93 published in 1987
Evaluate total effective dose equivalent to members
of U.S. public exposed annually from
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Medical sources
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Radon
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Cosmic and Terrestrial Radiation
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Consumer Products and
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Other Radiation Sources (occupational, nuclear fuel
cycle, radioactive fallout and miscellaneous sources)
NCRP SC 6-2:
Radiation Exposure of U.S. population
• Dennis M. Quinn - Chairman
• Kenneth L. Miller - Chairman
Medical
• Bruce Thomadsen - Chairman
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Natural Background Radiation
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Consumer Products and Miscellaneous Sources
Occupational
Published in
1987
• Daniel J. Strom - Chairman
• Orhan H. Suleiman - Chairman
Natural
Technologically enhanced
New report expected to be published in 2008
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
NCRP Report 93*:
Annual effective dose equivalent to US population circa 1980-82
• Natural Sources
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Radon
2.0 mSv
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Other
1.0 mSv
• Man-made Sources
1987
Natural 82%
Man-made 18%
3.0 mSv
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Medical
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Last major medical data used in NCRP Report
No. 93 are from 1982 or earlier
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0.53 mSv
• X-rays
To update NCRP Report 93 published in 1987
and NCRP report 100 published in 1989
0.6 mSv
Occupational, Consumer
products, nuclear fuel cycle
and other miscellaneous
products
0.07 mSv
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1989
Purpose
Evaluate the current total effective dose to
members of U.S. public exposed annually from
0.39 mSv
• Nuclear Medicine 0.14 mSv
Medical Radiation Exposures
* Published in 1987
NCRP SC 6-2: Medical Subgroup Members
Chairperson: B. Thomadsen,University of Wisconsin
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Goals
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Estimate current radiation exposure to US population
M. Bhargavan
American College of Radiology
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Number and types of medical procedures
D. Gilley
State of Florida
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Effective radiation dose per procedure
J. Gray
DIQUAD, LLC
J. Lipoti
State of New Jersey
M. Mahesh
Johns Hopkins University
J. McCrohan
US FDA
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Radiography, Fluoroscopy, Mammography, Dental
F. Mettler
Univ of New Mexico VA
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Interventional
T. Yoshizumi
Duke University
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CT
M. Rosenstein
Scientific NCRP Consultant
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Nuclear Medicine
K. Kase
Stanford SC 6-2 Chair
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Radiation Therapy
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Examine past and future trends of medical exposures
Modalities
Assumptions
Methods
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Collective doses estimated independently for each
modality
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Modality groups:
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report
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CT, Nuclear medicine, Radiography & Fluoroscopy,
Mammography, Interventional, Dental, Chiropractic
Radiology, Bone Densitometry, and Radiation Therapy
Procedures within each modality categorized by
body part or organ system
Benefit exceeds risk: Issue not examined in this
Data sources:
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Multiple data sets
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Incomplete data sets required assumptions and cross
checking between data sets
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Weighting Factors: Used ICRP 60 (1990). Past
reports used older ICRP 26 (1977) and new
factors are suggested
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Modalities & procedures considered in the report
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Major and minor data sources
Computed Tomography (CT)
Nuclear Medicine Procedures
Radiography and Fluoroscopy
Interventional Radiography
Mammography
Dental and Chiropractic
Bone Densitometry
Radiation Therapy
IMV Benchmark Reports
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Based on responses from hospitals and estimated
to identified universe of US hospitals (~7000)
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Surveys had high response rates (~60%)
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Reports used: CT, nuclear medicine, cardiac
catheterization, radiography-fluoroscopy,
angiography, mammography, PET and radiation
therapy
Reports between 2003-2006
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Procedure counts available for 1991-2006
Grouped by HCPCS-CPT, patient age and
gender
Summarized data for 2003-2006 used for
comparisons
4 to 7 million enrollees, mostly male
Women and children under-represented
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Commercial (IMV Benchmark)
Medicare payment data (2003-2005)
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VA Health Care System
Claims data from large national employer plan
US FDA
CRCPD
State radiation programs
Large hospitals
American College of Radiology
Literature
Medicare Payment Data
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Claims data for Medicare fee-for-service enrollees
Summarized procedure counts for each modality and
sorted by Common Procedure Coding System (HCPCS)
Common Procedural Terminology (CPT) code
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100% medical claims from 1997-2004
Accounts for nearly 40 million enrollees
Mainly covers persons >65 years old and disabled
Represents one-third of all utilization and one-seventh of
US population
Data includes all ages
Veterans Administration (VA)
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Large National Employer Program (LNEP)
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Claims data available for 2003
Data summarized by modality and body part
4 millions nationally distributed
All ages and gender included
Data used for spot-check distributions of
procedures for certain modalities
Data: Reconciliations and Limitations
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Results
Procedure counts and distribution from IMV reports
Distribution of procedure counts across body part
or organ system was matched with data from other
data sources
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Limited data available on volumes of chiropractic
and dental imaging
Computed Tomography (CT)
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Annual growth over 1993-2006:
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Computed Tomography
Number of CT procedures in US
IMV Benchmark Report on CT, 2006
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
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CT Procedures > 10% vs US population < 1%
Nearly 67 million CT procedures in US in 2006
Data correlated to nearly 7649 hospitals in US
Pediatric CT ~ 8-10% of total procedures
Categories of CT procedures
(62.0 million in 2006)
HCAP: ~80% of all CT procedures
IMV 2006
Distribution Pattern of CT Scanners in US*
CT scans of Abdomen and Pelvis
Exam distribution vs US Population*
~ 20% of population >55 years, receives >55% of CT scans
IMV 2006
* LNEP 2003
CT: Procedures vs Collective Dose
Preliminary Results for CT (2006)
Number
(millions)
%
Collective dose
Person Sv
%
Head
19.0
28
38,000
8.7
Chest
10.6
16
74,000
17.0
Abd/Pelvis
25.4
38
254,000
58.0
Extremity
3.5
5
500
0.1
CT Angiogram
4.3
6
56,000
12.8
Miscellaneous
4.2
6
15,000
3.4
TOTAL
67
84%
438,000
Preliminary results not yet reviewed and approved by NCRP Council
Collective dose
Effective dose per person from CT
~438,000 person Sv
~1.46 mSv
Preliminary results not yet reviewed and approved by NCRP Council
Radiation dose from CT:
Then (1980) and Now (2006)
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According to NCRP report 100
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According to current estimations
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Collective dose for CT
3,700 person Sv
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Collective dose for CT
440,000 person Sv
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Effective dose per capita
~1.5 mSv
and some radiation exposure
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Nuclear Medicine
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Annual growth over 1993-2005:
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Nearly 17 million nuclear medicine procedures in US
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Nuclear Medicine
in 2005
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Data correlated to nearly 7200 hospitals in US
Largest increases in cardiac procedures
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Number of nuclear medicine procedures in US
Nuclear Medicine Procedures > 5% vs US population < 1%
1% in 1973 to 57% in 2005
Type of Nuclear Medicine Procedures
IMV 2005
IMV Benchmark Report on NM, 2005
Nuclear Medicine: Procedures vs Collective Dose
Procedures by categories (%)
Collective dose
Effective dose per person
Preliminary Results for Nuclear Medicine (2005)
Collective dose by categories (%)
~231,000 person Sv
~0.80 mSv
Preliminary results not yet reviewed and approved by NCRP Council
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Number
millions
%
Collective dose
Person Sv
%
Brain
<0.1
<2
260
0.1
Thyroid
< 0.1
<2
400
0.2
Lung
0.74
4
2,000
0.9
Cardiac
9.80
57
188,000
85.2
GI
1.21
7
3,500
1.6
Renal
0.47
3
650
0.3
Bone
3.45
20
20,500
9.3
Infection
0.38
2
1,300
0.6
Tumor
0.34
2
3,900
1.8
Total
17.2
220,500
Radiation doses from Nuclear Medicine:
Then (1980) and Now (2006)
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According to NCRP report 100
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Collective dose for Nuclear Medicine
32,000 person Sv
Radiography & Fluoroscopy
According to current estimations
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Collective dose for Nuclear Medicine
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Effective dose per capita ~0.80 mSv
231,000 person Sv
Radiography & Fluoroscopy
Radiography: Procedures vs Collective Dose
Procedures by categories (%)
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Collective dose by categories (%)
Data includes mammography, dental,
chiropractic radiographic procedures,
bone densitometry & certain fluoroscopy
procedures
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Limited data available for dental and
chiropractic procedures
Collective dose
Effective dose per person from Radiography
~98,000 person Sv
~0.30 mSv
Preliminary results not yet reviewed and approved by NCRP Council
Radiation dose from conventional radiography and
fluoroscopy: Then (1980) and Now (2006)
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According to NCRP report 100
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Collective dose
71,000 person Sv
According to current estimations
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Collective dose
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Effective dose per capita
98,000 person Sv
~0.32 mSv
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Interventional
Interventional Fluoroscopy
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Preliminary Results for Interventional
Procedures considered
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Procedures
Number
(millions)
%
Collective dose
Person Sv
%
10
12,900
10
Non-coronary angiography diagnostic and
therapeutic procedures
Non-coronary
diagnostic
1.7
Cardiac catheterization procedures
Non-coronary
therapeutic
1.4
9
21,930
17
Cardiac
catheterization
4.6
28
63,210
49
Other
interventional
fluoroscopy
9.0
53
30,960
24
TOTAL
16.7
Other interventional fluoroscopy procedures
such as ERCP, Urinary studies, …
Effective dose estimations varies by order
of magnitude
129,000
Preliminary results not yet reviewed and approved by NCRP Council
Interventional: Procedures vs Collective Dose
Procedures by categories (%)
Collective dose by categories (%)
Radiation Therapy
Collective dose
Effective dose per person
~129,000 person Sv
~0.4 mSv
Preliminary results not yet reviewed and approved by NCRP Council
Radiation Therapy
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Different source of exposure to population than other
medical exposures
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Form of risks are different from diagnostic applications
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Concern for failure of function of target organ due to high dose
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Likelihood of secondary cancer
Even though data on number of radiation therapy
procedures are available, the dose delivered varies widely
and often unknown
Uncertainty in estimating an average dose is very high,
therefore not included in final estimation of radiation
exposure to US population
Preliminary Results*
Number
Procedures
%
Collective dose
(Person-Sv)
%
Per
capita
(mSv)
CT
67 million
16
440,000
49
1.50
Nuclear
Medicine
18 million
4
231,000
26
0.80
Radiography &
Fluoroscopy
324 million
76
99,000
11
0.30
Interventional
17 million
4
129,000
14
0.40
Modalities
Total
~426 million
899,000
~3.0
*NCRP SC 6-2
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Procedures vs Effective dose contributions
Radiation dose from Medical Exposure:
Then (1980) and Now (2006)
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Percent Procedures
Effective Dose Contributions
Effective dose per capita from medical radiation exposure is ~ 3.0 mSv
* Includes mammography & dental procedures
According to NCRP report 93
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Collective dose
123,000 person Sv
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Effective dose
0.54 mSv per capita
According to current estimations
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Collective dose
899,000 person Sv
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Effective dose
3.0 mSv per capita
Results not yet reviewed and approved by NCRP Council
NCRP SC 6-2 Preliminary Results*:
Medical Radiation Exposure to US population
Per capita radiation dose has increased ~ 500%
Radiation exposure to US population from all sources
The new pie chart!
US 1982 (NCRP 93)
x 5.5 =
3.0mSv
3.2
mSv
0.54 mSv
1980
CT contribution ~1.5 mSv
Medical 0.54 mSv per capita
Total 3.6 mSv per capita
2006
* These results have not been reviewed and approved by Council
Not to be disseminated or referenced
Discussions
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Results are snapshots, however, provides
insight regarding current and future trends
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Doses for procedures are averages and
individual doses may vary by a factor of 3-20
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US 2006
Final report expected in 2008
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Medical 3.0 mSv per capita
Total 6.25 mSv per capita
These results have not been reviewed and approved by NCRP Council
Not to be disseminated or referenced
Probable causes for increase in medical exposures
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Advances in medical technology
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Easy to use -
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Accessibility
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Economics in medical imaging
Demand of improved patient care
Challenges in early diagnosis
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Demand for improved temporal and spatial resolution
Out of the box solution, for ex: CT
Emergency Rooms - Outpatient - Doctor’s offices - …
Benefits from Medical Imaging
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Benefits outweighs the risks!
Early diagnosis have led to
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Increase in life expectancy
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Decrease in deaths due to cancers, cardiovascular and other
What should we do?
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Aware of risks of radiation when ordering x-ray
based examinations
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Essential to use most accurate information
when making risk benefit decisions
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Often risks are either underestimated or
massively overestimated
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Well-informed investigative decisions are key!
diseases
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Decreases in childhood mortality - not only in US but
globally - due to early diagnosis
Are more regulations required – Yes & No
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Yes, Appropriate regulations are required to
hinder/stop misuse of medical x-ray technology
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Yes, appropriate regulations are required to ensure
x-ray technology is operated at optimal settings with
proper QA in place and only qualified individuals
operates/uses the technology
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No, should not curb the development of new
technology or protocols or stop clinicians from
finding new ways to better care for their patients
What can we do?
• Examine radiation doses for different
procedures
• Identify and optimize factors
contributing towards radiation doses
• Image quality should not be
jeopardized when reducing dose
• Management of radiation dose is key!
Effective doses in CT procedures*
Computed Tomography
* Mettler, Huda, Yoshizumi and Mahesh, Radiology, July 2008
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Many patients have more than one CT examination
Sinus CT in Post Bone Marrow Transplant
Pediatric Patients
2002
Table 1: Number of CT scans performed for various age groups along with the average
and range of effective dose estimation.
2003
No. of CT scans
Age group
2004
2004
2005
Radiation Dose Report for a CTA Procedure
18.4
9.8
39.2
2 to 5
19
3.8
2
13
16.9
8.8
57.2
6 to 10
10
3.4
2
6
11.2
6.6
19.8
11 to 15
15
3.1
2
7
7.8
5
17.5
16 and above
16
3
2
6
6.6
4.4
13.2
Optimize CT settings
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1.0 mSv
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18.3 mSv
21.7 mSv
General Implications
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For example, digital vs screen-film mammography, 64 vs 4 MDCT
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As scan time becomes shorter, and more information can be gathered per visit, tendency
is to add more exams per visit
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A chest x-ray may be followed by a chest CT scan and chest CT scan may further include
with and without contrast scans
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Similarly, CT Angiography may be followed by CT Perfusion
• ‘How many of the medical exams are appropriate?’
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Maximum
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Recommendations to reduce radiation risk from CT
2.4 mSv
• However, number of exams performed per patient visit seems to increase
• For example:
Average Minimum
2
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exam can decrease
Effective dose (mSv)
Maximum
3.8
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• Advances in technology leads to increase in protocols
• With technological advances and optimization, often radiation exposure per
Average Minimum
4
Effective
dose (mSv)
Total effective dose (mSv)
No of patients
0 to 1
Reduce tube current (mA)
Use dose modulation techniques
Increase pitch
Reduce number of multiple scans with
contrast material
Eliminate inappropriate referrals for CT
Adopt Image Gently Campaign for
lowering dose
What can we do?
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Is educating public regarding radiation exposures
better? YES
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‘Web’ - can be a useful tool or a distracting tool
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Often when patients ask about their medical
exposures, clinic pays special attention regarding
their protocol settings
Delicate balance necessary - educating versus
scaring population about radiation exposures
Conclusions
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Advances in medical technology, clinical
applications, proliferation of imaging systems and
easiness to use and many other factors have
contributed to the overall increase in medical
radiation exposure
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Justify appropriateness of x-ray imaging procedure
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Understanding associated radiation dose and risks
are essential to obtain optimal benefit
Conclusions
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Overall, medical radiation exposure to US population
has increased significantly from last report
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Advances in medical technology, clinical
applications, proliferation of imaging systems and
easiness to use and many other factors have
contributed to the overall increase in medical
radiation exposure to US population
© Mahadevappa Mahesh, MS, PhD, FAAPM.
mmahesh@jhmi.edu
Johns Hopkins University, Baltimore, MD
Conclusions
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Results are snap-shot of radiation exposure to US
population from various medical procedures
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Doses for procedures are averages and individual
doses may vary by a factor of 3-20
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Benefit exceeds risk - however, this issue is not
examined in this report
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Final report is expected in 2008
Slice Wars!
Dose Wars!
Past – Present - Future