Transcript ABCs of Radiation Safety

2009 Pediatric and
Congenital/Structural
Fellows Course
Fluoroscopy and
Radiation Exposure
Thomas K. Jones, MD
Professor, Pediatrics and Medicine
University of Washington School of Medicine
Director, Cardiac Catheterization Laboratories
Seattle Children’s Hospital
2009 Pediatric and
Congenital/Structural
Fellows Course
Conflicts of Interest
None for purposes of this presentation
Acknowledgements
Thomas Bashore, MD, FSCAI
Stephen Balter, PhD, FSCAI
Joseph Babb, MD, FSCAI
Message
• Keep the x-ray source (the tube) as far
away from you (the operator) as possible
consistent with optimal imaging.
Radiation Safety Principle
• Use the least amount of magnification
consistent with seeing the object
adequately.
• BIGGER IS NOT ALWAYS BETTER!!
• A larger image means more radiation
– If it is necessary for adequate visualization, fine
– If it does not improve procedure safety or
performance, reduce the magnification
Stochastic effects
• Probability proportional to dose
• Severity independent of dose
• Assumed zero threshold
Risks are Radiogenic Cancer and
Genetic Damage
Deterministic effects
• Certainty of effect
• Severity is a function of dose
• Substantial threshold
High dose risks are:
hair loss, skin damage, cataracts,
and congenital abnormalities
Time
• Radiation is only produced
when the beam is on!
• Irradiate only when it is
necessary to observe motion.
• Last-image-hold and instant
replay can usually save dose.
Distance effect
Use the inverse square law to your advantage and
whenever possible move away from the x-ray source
as far as safety allows.
Distance
from Beam
Relative
Exposure Rate
1 step 2 steps 3 steps 4 steps
100
25
11
6
Shielding
Protective shielding can markedly reduce
staff risk. (when used!)
• Structural Shielding
• Mobile Shielding
• Personal Shielding
Protective Clothing
• Well tailored apron
• Thyroid collar
• Eye protection
Collimation
Wear Your Exposure Badge
• It is for your benefit
• The readings should correlate with your
workload
• Over-lead monitor on midline at neck level
• Under-lead monitor on midline at waist
level
• Weighted average for estimating
stochastic risk
Summary
• Safe use of radiography demands understanding
of basic radiation physics
–
–
–
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Sources of radiation
Proper positioning of patient in x-ray beam
Maintenance of I.I. close as possible to patient
Proper use of shielding
• Use the inverse square law of radiation exposure
to your advantage
• Use the least magnification consistent with
adequate visualization
• Only activate the x-ray when moving a device or
assessing and injection!
• Always wear your film badge and change it
monthly