1. Occupational Radiation Dose Management

2. Basis for Protection Requirements
Limit stochastic and non-stochastic effects
STOCHASTIC
Probability of an effect occurring, rather than its severity
Regarded as a function of radiation dose without a threshold
NON-STOCHASTIC
Severity is affected by dose
A threshold dose may need to occur before effect is recognized

3. ALARA A L R s ow s
easonably
chievable

4. Operator Radiation Sources
Sources of radiation for operator:
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.
Primary
Scatter
Leakage

5. Occupational Exposure: Scatter
Isoexposure lines during fluoroscopy

6. Scatter Radiation Levels
Effects of scatter radiation during mobile/portable fluoroscopy (C-arm procedures) and fluoroscopy exams.
Scatter radiation during portable fluoroscopy is more intense with the x-ray tube over the patient

7. 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.
Beam time =
Exposure

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

9. Tenth Value Layer (TVL)
Shielding
Half Value Layer (HVL)
Tenth Value Layer (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

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

11. 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

12. Find the cardinal principals at work in this picture.

13. Occupational Radiation Monitoring
Film Badges

14. Occupational Radiation Monitoring
Thermoluminescent Dosimetry (TLD)

15. Occupational Radiation Monitoring
Optically Stimulated Luminescent (OSL)Dosimeters

16. Legal Dose Limits in the United States
Annual
50 mSv/yr (5000 mrem/yr)
Lens of the eye
150 mSv/yr (15 rem/yr
Other organs
500 mSv/yr (50 rem/yr)
Cumulative whole body
10 mSv (1000 mrem)×age
Pregnancy, entire
5 mSv (500 mrem)
Pregnancy, monthly
0.5 mSv (50 mrem)

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What’s Next?
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