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