MDCT Safety Issues

1
MDCT Safety Issues

• Kimberly E. Applegate, MD, MS
• Riley Hospital for Children
• Indiana University

Financial disclosures none
2
Overview

• FDA warning on devices
• Contrast injectors
• Creatinine in children
• (Sedation)
• CT and medical radiation
• The Image Gently Campaign

3
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 gt7 million CTs in children
• 1 in every 4-10 Americans get CT annually
• NRCP 2002

4
CT and MRI rated most important innovation in
20th century healthcare

• Fuchs VR, Sox HC. Health Affairs 20012030-42
• 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!

5
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

6
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)

7
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

8
Creatinine in ChildrenSuggested cut-off levels

• Neonates to 6 months gt0.3
• 6 months-1 year gt0.6
• 1-5 yrs gt0.8
• 6-12 ys gt1.0
• For children gt12 years old creat gt1.1
• For adults gt21 years old creat gt1.5
• based on Schwartz formula (muscle mass)

9
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
10
Question 1

• There is direct evidence that radiation from
  medical imaging causes cancer.
• True
• False

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Answer False

• Indirect evidence from Hiroshima Atomic Bomb
  survivors
• Linear No Threshold Model

12
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.

13
What is Low-level Radiation?

• lt 100-150 mSv
• or 3-10 abdominal CTs

14
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
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Low-level Radiation Harmful? Support

• NASBEIR VII
• NCRP
• ICRP
• NCI
• FDA
• Radiology RSNA, SPR

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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?
• 1001
• 101
• 11
• 110
• 1100

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Understanding Risks

• Risk of severe allergic reaction from low
  osmolar IV contrast
• lower in children than adults
• 1100,000
• Risk of fatal cancer induction from 1 (adult
  dose) abdominal CT scan in a child
• 11,000 (Brenner, AJR 2001)

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Question 3- Radiography

• Is there an added risk of breast cancer after
  adolescent exposure to spine radiographs for
  scoliosis evaluation.
• Yes
• No

19
Answer 3 YesScoliosis 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

20
Our very own CatScan
CT exams represent 2/3 medical radiation
exposure in USA
21
Bismuth ShieldsChest CT female breast dose

• Breast, thyroid, eye bismuth shields reduces
  dose by 30 (FL 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

22
Technique--Bismuth Shields

• Coursey C et al. AJR 2008190(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

23
Question 4 - Radiosensitivity

• Boys and girls are at equal risk of cancer
  induction from radiation.
• True
• False

24
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

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Lack of understanding of CT doses

• Lee et al 2004

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Lee et al radiology 2004
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Question 5 - CT

• What is the estimated contribution of CT to
  future cancer risk in the USA?
• .01
• .1
• 1
• 10

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Answer 1-2 Future Cancers from CT

• Brenner D and Hall E. Computed tomography--an
  increasing source of radiation exposure NEJM 2007
  29357
• Estimate that up to 2 future cancers in USA
  population due to current use of CT

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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

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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

32
Special Focus on Children

• Radiosensitivity
• Longer Life Expectancy
• CT scans in children often performed using
  adult techniques resulting in higher radiation
  dose

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The Image Gently Campaign

• Launched Jan. 2008 by SPR in alliance with
• Radiologists, Physicists, Technologists,
  Pediatricians
• Education focuse to decrease radiation exposure
  in children
• CT first module

Www.ImageGently.org
34
Image Gently Campaign

• Marilyn J. Goske, MD, Alliance Chair and Chair,
  SPR Board of Directors Cincinnati Childrens
  Hospital
• Goals/ Background of Campaign
• Scientific Background and Rationale
• Education/Marketing campaign overview and rollout
• The Website

35
Alliance Members

• 4 Founding SPR,AAPM,ACR,ASRT
• Now 33 organizations
• International (CAR, ESPR, RANZCR, SLARP)
• Represent gt500,000 members

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• Five Initiatives
• CT, NM, IR, CR/DR, Fluoro
• Three Components
• Radiologists, Physicists, Technologists
• Referring Physicians ALARA, presentations
• Parents

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The Message
38
Campaign Impact

• gt1500 imaging providers took pledge
• Website
• gt 72,000 visits
• gt 6,000 downloads of guidelines on pediatric CT
  protocols

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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 1991303797-780

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Thank you!
Questions kiappleg_at_iupui.edu 317-278-6304
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CTA of Aortic Stents
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Lack of Understanding of Dose 2004 UK survey
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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

45
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

46
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

47
Lack of understanding of DoseAbdominal CT vs CXR

• An abdominal CT deposits the equivalent dose of
  about how many chest radiographs?
• 10
• 50
• 100
• 500

48
Steering Committee

• Marilyn Goske, MD, Alliance Chair - SPR
• 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

• . Marta Hernanz-Schulman, MD,  FACR
• 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

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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
CAGR ()
15
High-tech 20
11.4
9.2
8.3
10
7.2
High-tech 12.9
2.5
5
Low-tech 4.5
0
MRI
NUCMED
CT
INT
MAM
US
X-RAY
50
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)
Projected Growth 2002-2008 Projected Growth 2002-2008 Projected Growth 2002-2008 Projected Growth 2002-2008
MRI CT Scan Ultrasound X-RAY
133 122 57 (9)
Source Sg2