1. Radiation Monitoring and Protection
Rad T 110
Radiation Monitoring and Protection

2. Personnel Monitoring
Required when a worker may receive 10% or more of the annual MPD
Typically monitoring is done when 1% is expected
Placement
Collar level
Outside the apron if used
Second may be used for pregnancy
Extremity monitors also

3. Types Film badges OSL; MC device today 10 mrem to 500 rem Cheap
Aluminum oxide which is read by a laser
Typically worn for 2 months
1 mrem and sensitive to 5 keV to 40 MeV of energy

4. Types cont. TLD Pocket ionization chambers Lithium floride
Reasonably sensitive
Cannot be re-read
Pocket ionization chambers
Good for immediate feedback
Not very reliable
Sensitive to mechanical energy

5. Dosimetry Reports
Deep
Eye
Shallow doses

6. Patient Protection Effective Communication Verbal messages
Concise instructions
Appropriate communication

7. Immobilization Voluntary motion Involuntary motion Lack of control
Immobilization devices work with this group
Involuntary motion
Fast exposure times with high mA helps
Possibly increasing kVp will help
15% rule shorter exposure
Fast film/screen combinations

9. Beam Limiting Devices Diaphragms Cones Collimators
Limit the amount of tissue the beam exposes
Also, limit the amount of scatter produced
Our exposure

10. Variable Collimator
2 sets of lead shutters limit the divergence of the beam
Collimator and light field
+/- 2% of the SID
Positive beam limitation (PBL)
Automatic collimator, collimates to the field size put in the bucky tray

11. Filtration Total filtration Inherent Added
Inherent plus added filtration
Inherent
Glass envelope
Oil
Window of the tube housing
0.5 mm Al
Added
Aluminum added to meet requirements

12. Total Filtration 2.5 mm Al > 70 kVp 1.5 mm Al 50 – 70 kVp
Mobiles/portables and Fluoro units are required to have at least 2.5 mm Al

13. Long wavelength photons
Filter
Short wavelength photons

14. Half Value Layer (HVL)
This is the amount of aluminum required to reduce the beam intensity to half its original value.
This is variable based on the selected kVp
As kVp is increased the penetrability of the beam increases
Therefore, the amount of Al necessary to halve the beam intensity will have to increase as well.

15. Protective Shielding Gonadal shields
Gonads need to be shielded when they are within 5cm of the beam
Unless shielding will obscure anatomy
Required to have at least 0.5 mm Pb

16. Types of Gonadal Shields
Flat contact
Shadow
Shaped contact
Clear lead

17. Specific area shielding
Breast during scoliosis screening
Clear lead filter
PA instead of AP

18. Compensating filters Trough or bilateral wedge Wedge filter
For chest images
Wedge filter
Specialized metal filters
Copper

20. Technical Factors Technique charts High kVp low mAs techniques
This is within a specific body part or region

21. Film Processing and QC
The processor has to work correctly. If not, films will be poor and repeats necessary.
QC insures that the processor is maintained to a standard level of acceptance

22. Film/Screen Rare earth screens are generally faster
This occurs due to their higher atomic number which results in a higher absorption of photons. Consequently, more light is produced per photon meaning less photons have to be used for a good film.

23. Grids Prevent scattered radiation from reaching the film.
They actually increase pt dose.
However, film quality is dramatically improved.

25. Repeat Analysis
Systematic review of repeated films to determine trends that can be eliminated thru education, procedural changes, or equipment maintenance.

26. Unnecessary Procedures
Make sure films are completed and recorded.
Listen to pts about possible previous exams.
When in doubt ask.

27. SID Must be a minimum of 12 inches
The longer the SID the lower the pt dose

29. Digital Imaging
CR and DR are the two methods currently used for digital diagnostic imaging
Images are displayed on a computer for viewing
Analogous to digital pictures at home
Image quality can be manipulated post acquisition
Possible reduction in repeats

30. Fluoroscopy Procedures
High pt dose
Potentially high tech exposure
Exams provide dynamic info
‘real time’ feedback for positioning of devices

31. Dose recording to patients
ESE
Entrance skin dose
GSD
Genetically significant dose
Bone marrow dose

32. Pregnant pts Should not be radiographed
If necessary, informed consent should be obtained
Pts needed to be asked about potential pregnancy before the exam begins

33. Pediatrics More radio-sensitive than adults More likely to move
Need to get instructions they understand not fear
Gonadal shielding collimation

34. Protection of Personnel
MPD
ALARA

35. Dose Reduction Methods
No repeats
Patient is the source of scatter
Filtration
Protective apparel
Technical factors

36. Pregnant personnel Lower MPD Protective apparel Additional monitoring
Work schedule alteration

37. Basic Principles of Protection
Time
Distance
Shielding

38. Structural Shielding Primary Secondary Operator booth 7 feet high
1/16 in Pb
Secondary
1/32 in Pb
Operator booth
Photons should scatter at least twice before entering the booth area
Secondary barrier