1. Stacy Kopso, M.Ed., RT (R)(M)
Radiation Protection
Stacy Kopso, M.Ed., RT (R)(M)

2. Film Badges
Thermoluminescent Dosimeters
Optically Stimulated Luminescence Dosimeters
Pocket Dosimeters
Dosimetry reports
Radiation Survey Instruments
Dose limits
Principles of personnel exposure reduction
Construction shielding
Protective garments

3. Monitoring of personnel

4. Monitoring of Personnel
Late effect of radiation
Exposure to intermittent low doses of radiation over a long period of time
Cancer and genetic effects
Effective dose limits have been implemented to lessen the possibility of the occurrence of early and late effects of radiation

5. Monitoring of Personnel
Monitoring is mandatory when personnel are likely to receive 25% of the annual effective dose-equivalent limit
Dosimetry- measurement of ionizing radiation doses to personnel. Record external doses. Not a protection device!
Film badges
Thermoluminescent dosimeters (TLD)
Optically stimulated luminescence dosimeter (OSL)
Pocket dosimeters
Normally monitored monthly
Records monthly, quarterly, yearly and lifetime exposure
Worn outside lead apron at collar level (different locations for specific badges)
Pregnant woman
2 badges
Collar outside apron
Waist under apron

6. Monitoring of Personnel
Film Badges
Special radiation-dosimetry film (similar to dental) contained in a light proof package
Film is enclosed in a plastic holder
Metal filters shield certain parts of the film that permit estimates of dosage and radiation energy
Shallow and deep doses can be calculated according to the amount of darkening of the film after processing
Worn outside apron at collar level
Worn monthly

7. Monitoring of Personnel
Worn at collar level outside of lead apron
Control badge
kept in a radiation free area
Serves as a baseline when compared with the rest of the film badges
Can only be worn during work hours
Kept away from sources of radiation and excessive heat and high humidity

8. Film Badge Advantages Disadvantages Simple to use Not reusable
Inexpensive
Low limit of sensitivity (10mrem)
Readily processed by laboratories
Accuracy limited to (+ or – )10-20%
Provide a permanent record
Susceptible to heat, humidity and light leaks

10. Monitoring of Personnel
Thermoluminescent Dosimeters
Contain lithium fluoride or calcium fluoride crystals
When exposed to ionizing radiation these crystals store radiant energy when heated
As they are heated the crystals release energy as light
This is measured by a machine that documents the radiation exposure based on how much light is emitted
There is a direct relationship between the intensity of light emitted and the radiation dose received by the crystals
Commonly worn as finger rings by nuclear medicine personnel (handle radioisotopes)

11. Thermoluminescent Dosimeter
Advantages
Disadvantages
Can be made very small
No permanent record (no archive)
Durable
Expensive
Low exposure limit (5mrem)
Accuracy +/- 5%
Less sensitive to heat
Can be worn for three months
Are reusable

12. TLD

13. Monitoring of Personnel
Optically Stimulated Luminescence Dosimeter (OSL)
Contains filters composed of aluminum, tin and copper
Houses a thin strip of aluminum oxide
The strip is stimulated by using a laser light and becomes luminescent in relation to the amount of radiation it has received
Capable of measuring different energy ranges determined by the amount of luminescence detected in the areas underneath the filters
These various ranges of energy correspond to deep, eye, and shallow doses

14. Optically Stimulated Luminescence Dosimeter
Advantages
Disadvantages
Measurement range from 1 mrem to 1,000 mrem (most sensitive reader)
More expensive than film or TLD
Accuracy +/- 15%
Precision within +/- 1 mrem
Energy range 5keV to 40MeV
Complete re-analysis if necessary
Bimonthly readout offered
Tamper proof badge
Not affected by heat or humidity
Whole body, collar, waist (fetal), wrist
Measures exposure to x-rays, gamma rays and beta particles

16. Monitoring of Personnel
Pocket Dosimeter
Sensitive
Instantaneous reading
Must be recalibrated daily
Only for exposures up to 200mR
Ionization chamber inside
Review the dosage by viewing a scale through an eyepiece located on the end of the dosimeter

17. Pocket Dosimeter Advantages Disadvantages
Provides an immediate exposure reading
No permanent record
Measures up to 200mR
Not damage proof

18. Pocket Dosimeter

19. Monitoring of Personnel
Dosimetry report
Measured in mrem
“M” minimal exposure (1mrem)
Must transfer the cumulative total exposures and the remaining dose to new employer

20. Radiation safety officer (RSO)
Determines if an employee has received an overexposure based on the report, the employee is counseled by the RSO
Medical physicist, health physicist, radiologist or any other qualified person

21. Radiation survey instruments

22. Radiation survey instruments
Used to detect and measure radiation
Geiger-Muller detector
Detects alpha and beta radiation
Inert gas-filled tube that briefly conducts electricity when a particle or photon of radiation temporarily makes the gas conductive
Tube puts out a pulse which is displayed by a needle, lamp or audible clicks

23. Geiger-Muller Detector

24. Radiation survey instruments
Gas ionization chamber (cutie pie)
Measures x-ray, gamma, alpha and beta
Used for measuring dose rates
Shielding effectiveness
Source containers
Radiation areas monitoring
Checking results following decontamination procedures

25. Cutie Pie

26. Dose limiting recommendations

27. Dose-Limiting Recommendations
ALARA
As low as reasonably
Time, Distance, Shield
NRC ,State, Joint Commission (JC)
Enforces radiation protection guidelines
State license(varies per state)
Radiation machine registration (yearly)
Effective Dose limit/Dose equivalent limit- the lowest dose of radiation that will maintain health with no ill effects

28. Dose-Limiting Recommendations
Diagnostic radiology personnel
Annual effective dose limit
____rem 5
____ mSv 50
_____ mrem
5,000
Negligible individual dose (NID)
1mrem/year
Minimal amount which does not need to be reported on the dosimetry report

29. Dose-Limiting Recommendations
Public
Annual effective dose limit for infrequent exposure
____rem .5
____mSv 5
_____mrem
500
Frequent exposure
.1 rem (1 mSv)

30. Dose-Limiting Recommendations
Occupational Exposures (NCRP # 116)
Dose Limits
Whole-body
5 rem (50mSv)
Lens of eye
15 rem (150mSv)
Skin/Extremities
50 rem (500 mSv)
Whole body cumulative (lifetime)
30 yr old- 30rems
Age x 1 rem (age x 10mSv)
Fetus full gestation
.5 rem (5mSv)
Fetus per month
.05 rem (.5 mSv)

31. Deep Dose Equivalent (DDE) Shallow Dose Equivalent (SDE)
External whole body exposure
Shallow Dose Equivalent (SDE)
External exposure of the skin or extremity
Eye Dose Equivalent (EDE)
external exposure of the lens of the eye

32. mAs and Intensity
Doubling the mAs, doubles the skin exposure, as long as other factors are held constant (factor of 2)
If an original intensity was 200 mR and the mAs value is increased from 10 to 20 mAs, what is the new intensity?
400 mR (increase by a factor of 2) Directly proportional
If an original intensity was 200 mR and the maS value is decreased from 100 mAs to 50 mAs, what is the new intensity?
100 mR (decrease in ½)

33. kVp and Intensity
Changing kVp affects radiation intensity by the square of the ratio
If 50 kVp produces an intensity of 200mR, what is the new intensity at 100 kVp?
400 mR (increase by 4x)

34. Structural shielding construction

35. Structural Shielding Construction
Primary protective barriers
Located perpendicular to the line of travel of the primary x-ray beam
1/16 inch of lead (PB)
Extends up to 7ft from the floor ( height of the upright bucky)

36. Structural Shielding Construction
Secondary Protective Barriers
Located parallel to the line of travel of the primary x-ray beam
Cover areas exposed only to scatter and leakage radiation
1/32 inch lead (Pb)
½ overlap on primary barrier
Plaster or concrete often serves as a secondary barrier without adding lead

37. Structural Shielding Construction
Control booths
Secondary protective barrier
Window 1.5mm lead (Pb)
7 feet high

38. Structural Shielding Construction
X-ray tube
Lead lined metal covering
1.5mm (1/16 inch) Pb
Reduces leakage radiation to not exceed 100mR/hr at 3 feet (1 meter)

39. Structural Shielding Construction
Factors that determine protective barrier thickness include distance, time of occupancy, workload and use.
Time of occupancy
Amount of time a hospital area is occupied by people
Controlled area
Area occupied by radiation personnel (factor of 1)
Reduce the exposure rate to ˂100 mR/week
Uncontrolled area
Area occupied by non-radiation personnel (public)
Reduce exposure to ˂10mR/week
Hallways= factor of ¼
Stairways and elevators= factor of 1/16

40. Structural Shielding Construction
Workload
Weekly average tube current and tube operating time
Measured in milliampere-minutes/week
Use factor
Percentage of time that the x-ray beam is energized and directed toward a particular wall
Primary & secondary wall barriers/use factor of 1
Not a primary/ use factor of ¼

41. Protective Garments

42. Protective Garments Lead apron High atomic number
Evaluated by half-value layers (HVLs)
The lead thickness that will reduce the intensity of radiation to 50%
Worn during fluoro work, portables, holding a patient
Lead thickness of
.25 .5
1mm Pb
X-ray attenuation at 75 kVp for 1mm Pb is 99%
Maternity apron
.5mm Pb + 1mm Pb around abdomen area

43. Lead Apron

44. Minimum lead equivalent NCRP #102
.25 mm Pb
.5 mm Pb
Gloves
Apron
Bucky slot cover
Thyroid
Curtain
Overhead barrier
.35 mm Pb
Glasses

45. Exam considerations

46. Exam Considerations Mobile exam Proper communication Clear room
Shield other patients and pt
Radiographer should position himself at right angles to the patient
Go around a corner if possible
Exposure switch
6 feet

47. Exam Considerations Fluoroscopic Exam Wrap around apron Lead gloves
Bucky slot cover
Lead drape

48. Exam Considerations Fluoroscopic exposure switch
Foot pedal or hand switch
Deadman (requires constant pressure)
Cumulative timing device
Produces an audible signal when 5 minutes of fluoro time has been used. Must be reset.
Intermittent/Pulsed fluoroscopy
Reduces patient exposure
X-ray intensity
≤10 R/min
HLCF ≤5 R/min

49. Exam Considerations
Source to tabletop distance ˃12inches (30cm) for mobile fluoro ˃15 inches (38cm) for fixed fluoro Total Filtration 2.5mm Al Image intensifier 2mm Pb

50. Inverse Square Law
The intensity of radiation at a given distance from a point source is inversely proportional to the square of the distance of the object from the source
When the distance from the x-ray target is doubled, the intensity is ¼ as much as the original exposure
Formula
I1 = d22
I2 d12

51. Inverse Square Law

52. Inverse Square Law
If a radiographer stands 2feet from an xray tube and receives an exposure of 1 mR/hr, what will the exposure be if the radiographer stands 4 feet from the xray tube?
6 feet to 3 feet???
4 mR