fluoroscopy and radiation exposure thomas k. jones, md professor, pediatrics and medicine university...
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Fluoroscopy and Radiation Exposure
Thomas K. Jones, MDProfessor, Pediatrics and Medicine
University of Washington School of MedicineDirector, Cardiac Catheterization Laboratories
Seattle Children’s Hospital
2009 Pediatric and Congenital/StructuralFellows Course
Conflicts of InterestNone for purposes of this presentation
AcknowledgementsThomas Bashore, MD, FSCAIStephen Balter, PhD, FSCAIJoseph Babb, MD, FSCAI
2009 Pediatric and Congenital/StructuralFellows Course
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
Distancefrom Beam 1 step 2 steps 3 steps 4 steps
RelativeExposure Rate 100 25 11 6
Use the inverse square law to your advantage andwhenever possible move away from the x-ray sourceas far as safety allows.
ShieldingProtective 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– 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
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