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Radiation Dose Reduction:
Where are we headed?
Kimberly E. Applegate,
MD, MS
Emory University
Financial disclosures:
AIM (American Imaging Management) radiation
protection advisory board;
Springer book contract: Evidence-based Pediatric
Imaging
Overview
Rapid increase in utilization CT, nuclear
medicine
Increased technologic complexity
Decreased oversight and RP training
Public awareness
„
FDA warning CT brain perfusion
CT and medical radiation: Consent?
„
The “Image Gently Campaign”
CT is a popular tool
1st clinical use: 1972
Poorly monitored but rapid increase in use
25% worldwide CT use is in USA
Estimate*: 260,000,000/yr World
65,000,000/yr USA
Estimate: >7 million CTs in children
1 in every 4-10 Americans get CT annually
*NRCP 2002
CT and MRI rated most important
innovation in 20th century
healthcare
Fuchs VR, Sox HC. Health Affairs 2001;20:30-42
Survey of leading general internists in practice
274/387 responses, anonymous
Ranked 30 innovations
„ Based on “importance to your patient population”
CT and MRI ranked number 1!
Growth in high-tech services have made
diagnostic imaging the fastest growing
physician service in the United States
Distribution of Imaging Services (2003)
Growth rate for Imaging
Services (1997-2003)
CAGR (%)
20%
Low-tech
80%
15.8%
13.9%
15%
High-tech
20%
11.4%
9.2%
10%
8.3%
7.2%
2.5%
5%
High-tech 12.9%
Low-tech 4.5%
0%
MRI
NUC
MED
CT
INT
MAM
US
X-RAY
THE RADIATION BOOM
As Technology Surges, Radiation
Safeguards Lag
NY Times: January 26, 2010
„
„
Walt Bogdanich, investigative series on dx rad, rad
onc patient safety events
‘At a 2007 conference on radiation safety, medical
physicists went so far as to warn that radiation
oncology “does indeed face a crisis.” The gap
between advancing technology and outdated safety
protocols leaves “physicists and radiation oncologists
without a clear strategy for maintaining the quality and
safety of treatment,” the group reported.’
…As Technology Surges, Radiation
Safeguards Lag
‘Part of the problem is that hospitals may
skimp on quality assurance because,
depending on the state, it is voluntary,
medical physicists say’
“There are no limits about what can be
done, how it can be used, when it is
considered unsafe.”
Clinical Radiology
October 2004; 39:928-934
Question 1
There is direct evidence that radiation
from medical imaging causes cancer.
A. True
B. False
Answer: False, with caveats
Indirect evidence from Hiroshima
Atomic Bomb survivors
Hiroshima survivor studies in 5-100
mSv belt have small but stat sig
increased cancers
Linear No Threshold Model
Pierce and Preston (2000)
50,000 survivors
(1988-1994)
Risk of cancer at
low dose
„
50-150 mSv
Excess cancer
deaths
BEIR VII Summary - June, 2005
Excess Cancer & Leukemia
Cases/Deaths per 100,000 Exposed
What is Low-level
Radiation?
< 100-150 mSv
…or 3-10 abdominal CTs
Pierce and
Preston (2000)
50,000 survivors
(1988-1994)
Measurable risk
of fatal cancer at
low dose
„
50-150 mSv
Monument to martyrs of radiation
Low-level Radiation Harmful?
Support:
NAS—BEIR VII
NCRP
ICRP
NCI
FDA
Radiology: ACR,RSNA,SPR
Question 2
What is the relative risk of a severe allergic
reaction to iodinated contrast versus
fatal cancer induction from an abdominal
CT in a child?
A.
B.
C.
D.
E.
100:1
10:1
1:1
1:10
1:100
Understanding Risks
Risk of severe allergic reaction from
low osmolar IV contrast:
• lower in children than adults
• 1:10,00 to 1:100,000
Risk of fatal cancer induction from 1
(adult dose) abdominal CT scan in a
child:
• 1:1,000 to 1:2500 (Brenner, AJR 2001)
Question 3- Radiography
Is there an added risk of breast cancer after
adolescent exposure to spine
radiographs for scoliosis evaluation.
A. Yes
B. No
Answer 3: Yes
Scoliosis Radiographs and
Breast Cancer Risk
M Morin-Doody et al. Spine 2000
NIH study of 138,000 radiographs
Dose dependent excess risk of later
breast cancer*
*Most were AP rather than PA
CT exams represent
2/3 pediatric medical
radiation
exposure in USA
Our very own
CatScan
Bismuth Shields
Chest CT & female breast dose
Breast, thyroid, & eye
bismuth shields reduces
dose by 30% (F&L Medical,
Vandegrift, PA)
Lead apron shielding
outside of scan areas
(politically correct)
AJR 2005; Parker et al.
CTA for PE studies: 20
mSv
2 view Mammogram: 2
mSv
Technique--Bismuth Shields
Coursey C et al. AJR 2008;190(1)
Pediatric chest MDCT using tube current
modulation: effect on radiation dose with
breast shielding (GE)
Place shield after obtaining scout image
to avoid Auto mA compensation due to
density of shield
ED 35% lower; breast dose 26% lower
Question 4 - Radiosensitivity
Boys and girls are at equal risk of cancer
induction from radiation.
A. True
B. False
Differential radiation risk
NAS 1990: women 5% higher cancer
death risk than men
BEIR VII 2005:
„
„
„
women 38% higher cancer death risk than
men
Infants 3-4x higher risk compared to adults
aged 20-50
Girl infants double risk of boy infants!
www.ieer.org/comments/beir/beir7pressrel.html
Lack of understanding of
CT doses
Lee et al 2004
Lee et al radiology 2004
UK Lack of Understanding of Dose:
A global concern
Question 5 - CT
What is the estimated contribution of
CT to future cancer risk in the
USA?
A.
B.
C.
D.
.01%
.1%
1%
10%
Answer: 1-2%
Future Cancers from CT
Brenner D and Hall E. Computed tomography-an increasing source of radiation exposure
NEJM 2007 29;357
Estimate that up to 2% future cancers in USA
population due to current use of CT
Marie Curie: Martyr to Radiation?
First winner of 2 Nobel
prizes:
-Physics (1903,w/ husband)
-Chemistry (1911)
-Only mother-daughter Nobel
laureate pair (daughter Irene
continued her research)
--Discovered Radium,
Polonium
--Died of leukemia, age 67,
presumed from radiation
exposure
New York Times 2002
Alice Stewart’s fetuses
are today’s premature
infants who we may
irradiate several times
each day.
ACR guideline on imaging
pregnant women (2007)
Table 5: Summary of Suspected In-Utero Induced Deterministic Radiation Effects*
Menstrual or
Gestational
age
Conception age
<0.05 Gy
0.05-0.1 Gy
>0.1 Gy
0 - 2 weeks
Prior to conception
None
None
None
3rd and 4th weeks
1st - 2nd weeks
None
Probably none
Possible spontaneous abortion.
None
Potential effects are
scientifically uncertain
and probably too subtle
to be clinically
detectable.
Possible malformations
increasing in likelihood as
dose increases.
None
Potential effects are
scientifically uncertain
and probably too subtle
to be clinically
detectable.
Increased risk of deficits in IQ
or mental retardation that
increase in frequency and
severity with increasing
dose.
None
IQ deficits not detectable at
diagnostic doses.
None
None applicable to diagnostic
medicine.
5th - 10th weeks
11th - 17th weeks
th
th
18 - 27 weeks
>27 weeks
3rd - 8th weeks
9th - 15th weeks
th
th
16 - 25 weeks
>25 weeks
None
None
*Taken from “ACR Practice Guideline for Imaging Pregnant of Potentially Pregnant Adolescents and Women with Ionizing Radiation”, derived from ICRP
Publications 84 (2001) and 90 (2004).
Radiation exposure in pregnancy
Mossman, KL, Hill LT. Obstet Gynecol. 1982;60:237-42.
… Approximately 1% of all pregnant women
are given abdominal x-rays during the first
trimester of pregnancy…In the authors'
experiences, radiation exposures usually
result in doses to the embryo of less than 5
cGy (rad); the resulting radiation risks are
usually small compared with other risks of
pregnancy.
Question 6
Radiologists today are at increased risk
of cancer.
A. True
B. False
Answer: False
…with caveats
Radiology 2004; (233)Yoshinaga S et al.
NIH review--8 cohorts of >270,000
radiologists and technologists
If employed after 1950, no added leukemia
risk (stochastic)
„
But short follow up of current workers and
increased uses of medical radiation
Cataract risk for IR and interventional
cardiologists (deterministic)
Radiation Safety
American College of Radiology white
paper on radiation dose in medicine. Amis
ES Jr, Butler PF, Applegate KE,etal; JACR 2007
Collaboration and Steps for all stakeholders
„
Consumers, vendors, physicists, techs…
Dose reference levels in new guidelines and all
Appropriateness Criteria
Special Focus on Children
Radiosensitivity
Longer Life Expectancy
CT scans in children
often performed using
“adult” techniques
resulting in higher
radiation dose
CTA of Aortic Stents
One PET CT in a 5 yr old…
23.3 mSv
1165 chest x rays, or…..
7.5 years of background
radiation
The “Image Gently” Campaign
Launched Jan. 2008 by SPR in
alliance with:
„
Radiologists, Physicists,
Technologists, Pediatricians
Education focus to decrease
radiation exposure in children
„
Www.ImageGently.org
CT first module
Image Gently Campaign
Marilyn J. Goske, MD, Alliance Chair and
Chair, SPR Board of Directors – Cincinnati
Children’s Hospital
Goals/ Background of Campaign
Scientific Background and Rationale
Education/Marketing campaign overview
and rollout
The Website
Alliance Members
4 Founding: SPR*,AAPM,ACR,ASRT
Now 50+ organizations
International (CAR, ESPR, RANZCR, SLARP)
Represent >500,000 members
Five Initiatives
„
CT, IR, CR/DR, Nucs,
Fluoro
Three Components
„
„
„
Radiologists,
Physicists,
Technologists
Referring Physicians
– ALARA,
presentations
Parents
The Simple Message
Campaign Impact
>2000 imaging providers taken pledge
Website
„
„
> 98,000 visits
> 9,400 downloads of guidelines on pediatric
CT protocols
New Collaborations: WHO, CDC, IAEA,
IRPA, others
Promoting Health Literacy:
free parent brochures
What Parents Should Know About CT Scans for Children:
Medical Radiation Safety
„
„
„
„
What is an xray?
What is a Cat scan?
Relative doses and risk
Web site references
Parent Brochure
Source Estimated effective dose (mSv)*
Natural background radiation.............................................. 3 mSv/yr
Airline passenger (cross country)......................................... 0.04 mSv
Chest X-ray (single view) ...................................................... up to 0.01 mSv
Chest X-ray (2 view) ............................................................. up to .1 mSv
Head CT ................................................................................ up to 2 mSv
Chest CT................................................................................. up to 3 mSv
Abdominal CT ....................................................................... up to 5 mSv
*imaging doses for children
Parent Brochure: Cancer Risk
Overall risk of a cancer death over
a person’s lifetime: 20-25%.
Estimated increased risk of cancer
over a person’s lifetime from a
single CT scan is estimated to be
a fraction of this risk (0.03- 0.05
%).
Estimated risk of one abdominal
CT has been compared to:
• driving 7,500 miles (accident
risk)
• motorcycling for 1,000 miles
(accident risk)
New downloadable pamphlets on
www.imagegently.org
8 page LONG Version
on Medical Radiation
Safety for parents „
„
„
detailed information
web sites
references
www.imagegently.org
2 page SHORT Version
on CT radiation safety
for parents
Useful as a handout for
„
„
„
Radiology departments
Emergency departments
Pediatric offices
My Child’s Medical Imaging
Record
Downloadable
Two sizes
„
„
2x 3.5 Wallet
8.5 x11
Date/ type of exam/
where performed
IAEA’s Smart Cards
International goals
Develop international working group to
augment both the web info and ideas for
the Campaign
„
„
„
„
Share information and strategies for
radiation protection
Promote communication of IGC messages
Translate web page and parent brochure
into Spanish
Parent brochure translations:10+ languages
Campaign Impact
>2000 imaging providers taken pledge
Website
„
„
> 98,000 visits
> 9,400 downloads of guidelines on pediatric
CT protocols
New Collaborations: WHO, CDC, IAEA,
IRPA, others
0.15
200
mAs
200 mAs
0.10
0.05
Head
Abdominal
0.00
0
10
20
30
40
50
60
70
Age at CT Examination (Years)
80
Estimated Lifetime Attributable Risk (%)
Estimated Lifetime Attributable Risk (%)
Image Gently CT protocol use impact:
Estimated % lifetime attributable cancer mortality risk,
as a function of age at exam, for a single CT exam
0.15
Adult: 200 mAs
Pediatric Abdomen: 50 mAs
Pediatric Head: 100 mAs
0.10
0.05
Abdominal
Head
0.00
0
10
20
30
40
50
60
70
80
Age at CT Examination (Years)
David Brenner
Interventional Radiology Module:
Summer 2009 Image Gently
• Checklist
for
performing IR
procedures in children:
How to decrease the
dose
• Power Point slide
presetation
• Parent brochure
• References
Next Step: CR/DR Summit Feb 4,
2010
Multidisciplinary conference—vendors,
regulators, scientific radiology
organizations
To understand needs of imaging
community in terms of dose, equipment
optimization, and training for imaging
infants and children
To follow: educational module roll out
Our Future: CT consent forms?
Courtesy of Perth AU public hospital radiology dept
Conclusion
“Medical technology (including
radiology) itself is not the problem. It is
why, how and how often it is used and
by whom which creates the problem.”
Chisholm R. Guidelines for radiological investigations
[editorial]. BMJ 1991;303:797-780
Thank you!
Questions: [email protected] 317-278-6304
Cancer and other causes of mortality among radiologic technologists in the
United States
Mohan AK, Int J Cancer. 2003 Jan 10;103(2):259-67.
Data are limited on the role of chronic exposure to low-dose ionizing radiation in the etiology of
cancer. In a nationwide cohort of 146,022 U.S. radiologic technologists (73% female), we
evaluated mortality risks in relation to work characteristics. Standardized mortality ratios (SMRs)
were computed to compare mortality in the total cohort vs. the general population of the United
States. Mortality risks were low for all causes (SMR = 0.76) and for all cancers (SMR = 0.82)
among the radiologic technologists. We also calculated relative risks (RR) for the 90,305
technologists who responded to a baseline mailed questionnaire, using Poisson regression
models, adjusted for known risk factors. Risks were higher for all cancers (RR = 1.28, 95%
confidence interval [CI] = 0.93-1.69) and breast cancer (RR = 2.92, 95% CI = 1.22-7.00) among
radiologic technologists first employed prior to 1940 compared to those first employed in 1960 or
later, and risks declined with more recent calendar year of first employment (p-trend = 0.04 and
0.002, respectively), irrespective of employment duration. Risk for the combined category of
acute lymphocytic, acute myeloid and chronic myeloid leukemias was increased among those
first employed prior to 1950 (RR = 1.64, 95% CI = 0.42-6.31) compared to those first employed
in 1950 or later. Risks rose for breast cancer (p-trend = 0.018) and for acute lymphocytic, acute
myeloid and chronic myeloid leukemias (p-trend = 0.05) with increasing duration of employment
as a radiologic technologist prior to 1950. The elevated mortality risks for breast cancer and for
the combined group of acute lymphocytic, acute myeloid and chronic myeloid leukemias are
consistent with a radiation etiology given greater occupational exposures to ionizing radiation
prior to 1950 than in more recent times.
Typical Radiation Doses
(mSv)
•
•
•
•
•
•
•
•
•
Average annual technician dose
Natural background
Dental x-rays
BE (marrow)
CXR (marrow)
Mammogram (breast)
Airline passenger
Flight crew / attendants
CT
3.2
3.5
.09
8.75
.01
.5 - 7.0
.03
1.6
< 1.0 – 30 mSv
Typical Medical Radiation
Doses: 5 year-old
CXR
(mSv*)
Equivalents
•
•
•
•
•
•
•
•
•
3-view ankle
2-view chest
Tc-99m radionuclide gastric emptying
Tc-99m radionuclide cystogram
Tc-99m radionuclide bone scan
FDG PET
Fluoroscopic cystogram
Chest CT
Abdomen CT
.0015
.02
.06
.18
up to 6.2
15.3
<.33
up to 3
up to 5
* This is effective dose; organ doses (in mGy) will differ
1/14th
1
3
9
310
765
16
150
250