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ABCs of Radiation Safety
Joseph D. Babb, MD FACC FSCAI
Professor of Medicine
East Carolina University
Conflicts of InterestNone for purposes of this presentation
AcknowledgementsThomas Bashore, MD FSCAIStephen Balter, PhD FSCAIFor allowing me to use some of their illustrations
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 monthly