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