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MDCT Safety Issues
Kimberly E. Applegate, MD, MS
Riley Hospital for Children
Indiana University
Financial disclosures: none
Overview
FDA warning on devices
Contrast injectors
Creatinine in children
(Sedation)
CT and medical radiation

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!
Things I used to know…
Iodinated contrast is bad for kidneys
Gadolinium contrast is safe for patient with renal
insufficiency
MRI is unsafe for patients with pacemakers and
similar devices
Under controlled condition, MRI may be safe
including with deep brain stimulators
CT is safe for patients with pacemakers and
similar devices
Recent FDA advisory – Occasional discharge of
devices, including vagal stimulators from
multidetector CT
Pacemakers and MDCT
FDA warning July 14, 2008:
Unintended “shocks” (i.e., stimuli) from
neurostimulators
Malfunctions of insulin infusion pumps
Transient changes in pacemaker output
pulse rate
McCollough et al. Radiology 2007; 243
 Phantoms, defib and pacer devices

Oversensing 20/21 at max dose (17/20 std dose)
Recommendations
Determine device type (after scout?)
If practical, move external devices out of
scan range
Shut off neurostimulators
Minimize x-ray exposure to device by:



Using the lowest possible x-ray tube current
consistent with obtaining the required image
quality
Minimize x-ray beam dwell time over the device
SCBTMR: Bismuth shield over device
Creatinine in Children
Suggested cut-off levels
Neonates* to 6 months: >0.3
6 months-1 year: >0.6
1-5 yrs: >0.8
6-12 ys: >1.0
For children >12 years old: creat >1.1
For adults >21 years old: creat >1.5
based on Schwartz formula (muscle mass)
Power-Injectable Venous Catheters:
Quality of enhancement &
Quality of life issue for patients
Children:
• PICCs (4,5 Fr)
• Central lines
(8-10 Fr)
IV flow rates 0.75-2 ml/sec
Question 1
There is direct evidence that radiation
from medical imaging causes cancer.
A. True
B. False
Answer: False
Indirect evidence from Hiroshima
Atomic Bomb survivors
Linear No Threshold Model
UNSCEAR 2000
“It should be noted, however, that
the inability to detect increased
[cancer] risks at very low doses
does not mean that those
increases do not exist.”
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: 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
• 1:100,000
Risk of fatal cancer induction from 1
(adult dose) abdominal CT scan in a
child:
• 1:1,000 (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 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
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
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
The “Image Gently” Campaign
Launched Jan. 2008 by SPR in
alliance with:

Radiologists, Physicists,
Technologists, Pediatricians
Education focuse 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 33 organizations
International (CAR, ESPR, RANZCR, SLARP)
Represent >500,000 members
Five Initiatives

CT, NM, IR, CR/DR, Fluoro
Three Components



Radiologists, Physicists, Technologists
Referring Physicians – ALARA,
presentations
Parents
The Message
Campaign Impact
>1500 imaging providers took pledge
Website


> 72,000 visits
> 6,000 downloads of guidelines on pediatric
CT protocols
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
CTA of Aortic Stents
Lack of Understanding of Dose:
2004 UK survey
Contrast Reactions
Who is at increased risk?
Prior reactions, allergies– not shellfish
Prophylaxis regimens:

Methylprednisolone (Medrol) 32mg p.o. 12
and 2 hours prior to contrast
administration
Procedures for Hydration
Saline 10 ml/kg IV bolus over 30-60 minutes
prior to CT (or 500ml)
No benefit: ½ NS, lasix, dopamine, mannitol,
aminophylline, ?fenoldopan,
?N-acetylcysteine;
Clear benefit of low vs hi osmolar, non-ionic
vs ionic contrast agents; ? isosmolar benefit
if renal dz (visipaque)
Bicarb may help
Why are Pediatric Radiation Doses so High?
• Unfamiliarity = high detail
-
pediatric disorders
normal variations
growth
complicated equipment
• Few guidelines, no regulation
• Most pediatric imaging is done
- not in academic centers
- not by subspecialists
Lack of understanding of Dose
Abdominal CT vs CXR
An abdominal CT deposits the equivalent
dose of about how many chest
radiographs?
A.
B.
C.
D.
10
50
100
500
Steering Committee
Marilyn Goske, MD, Alliance Chair SPR
. Marta Hernanz-Schulman, MD,
Kimberly Applegate, MD,
SPR and ACR
Jennifer Boylan
SPR
Penny Butler
ACR and AAPM
Michael Callahan, MD,
SPR
Brian Coley, MD,
SPR and ACR
Shawn Farley
ACR
Donald Frush, MD
ACR and SPR
SPR and ACR
Diego Jaramillo, MD, MPH,
SPR
Neil Johnson, MD
SPR
Sue Kaste. DO
SPR
Greg Morrison
ASRT
Keith Strauss, MD
AAPM and SPR
Nora Tuggle
ASRT
FACR
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)
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
Imaging service volume will continue to
increase as use of high-tech procedures
drive growth
Projected Growth in Imaging Procedures (2000-2008)
Volume of Imaging
Procedures (M)
600
500
400
281
299
2000
2001
323
349
374
401
430
450
471
300
200
100
0
2002
2003
2004
2005
2006
2007
2008
Projected Growth 2002-2008
Source: Sg2
MRI
133%
CT Scan
122%
Ultrasound
57%
X-RAY
(9%)