Occupational Radiation Dose Management

Basis for Protection Requirements Limit stochastic and non-stochastic effects Stochastic = Probability of an effect occurring, rather than its severity. Non-stochastic = Severity is affected by dose.

ALARA As Low Reasonably Achievable

Operator Radiation Sources Sources of radiation for operator Primary Scatter Leakage Operators of fluoroscopes receive their exposures through three distinct mechanisms. Each will be described in detail in the following slides. Operators of fluoroscopes are required by regulation to wear a personnel dosimeter or radiation monitor. The most common type of dosimeter is the film badge. The darkness or density of the film in the badge indicates the amount of radiation detected by the film badge. Badges are distributed by companies who maintain high quality control for accurate radiation measurement. There are several important features one should know about personnel dosimeters: 1. The dosimeter's only function is to detect radiation. In no way does it directly protect the operator. 2.Dosimeters are mailed in groups along with control dosimeters so that radiation received in transit can be subtracted from actual personnel exposures. This only occurs if personnel dosimeters are returned with the control dosimeter. When a personnel dosimeter is turned in late, the dosimeter does not get mailed with the control dosimeter. 3. There is a right way and wrong way to wear dosimeters. In most cases it is recommended that the dosimeter be worn outside the lead apron on the collar. When film is used it must be worn properly installed in the badge holder with the film (name) side out. There are various filters in film badges which allow an approximate determination of beam energy. These filter patterns must be visible on the film to obtain a valid radiation measurement.

Occupational Exposure: Scatter Isoexposure lines during fluoroscopy

Operator Protection: Time Minimize “beam-on” time Your exposure is directly proportional to beam time Although we must always be concerned about patient exposures, our operators are present day in and day out in a radiation environment. The four cardinal principles of operator protection are time, distance, shielding, and collimation. Each is explained in the following slides.

Operator Protection - Other Distance Stand as far away from table as possible Shielding Lead drapes (except on C-Arms) Bucky slot cover Intensifier is primary barrier Protective garments ( aprons, thyroid) Collimation Anything that reduces patient exposure

Shielding HVL TVL Tube Potential Lead (mm) Concrete (in) 40 kVp 0.03 0.13 0.06 0.40 60 kVp 0.11 0.25 0.34 0.87 80 kVp 0.19 0.42 0.64 1.4 100 kVp 0.24 0.60 0.80 2.0 125 kVp 0.27 0.76 0.90 2.5 150 kVp 0.28 0.86 0.95 2.8

X-Ray Attenuation of Lead Aprons Equiv Thickness (mm Lead) Wt (lb) 50 kVp 75 kVp 100 kVp 0.25 3-10 97 66 51 0.50 6-15 99.9 88 75 1.00 12-25 99 94

Weighting Factors for Various Types of Radiation Type of Energy Range Radiation Weighting Factor (Wr) X- and gamma rays, electrons 1 Neutrons, energy < 10 keV 5 10 keV to 100 keV 10 >100 keV to 2 MeV 20 > 2 MeV to 20 MeV >20 MeV Protons 2 Alpha particles

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