Ch 36 Designing for radiation Flashcards
What are the radiation protection features of a radiographic imaging system?
- Source-to-Image Receptor Distance Indicator
- Collimation
- Positive-Beam Limitation
- Beam Alignment
- Filtration
- Reproducibility
- Linearity
- Operator Shield
What are fluoroscopic protection features?
- Source-to-Skin Distance
- Primary Protective Barrier
- Filtration
- Collimation
- Exposure Control
- Bucky Slot Cover
- Protective Curtain
- Cumulative Timer
- Dose Area Product
What are factors affecting barrier thickness?
- Distance
- Occupancy
- Controlled Area vs Uncontrolled Area
- Workload
- Use Factor
- kVp
What are materials used for Primary Barriers?
- Lead
- Concrete
What are materials used for Secondary Barriers?
- Steel
- Glass
- Gypsum
- Wood
What are the (2) reasons for protection against secondary barriers?
Leakage radiation
Scatter radiation
What does filtration do?
Reduces exposure to the patient’s skin and superficial tissue by absorbing most of the lower energy photons.
What are the (2) types of filtration available?
- Inherent filtration
2. Added filtration
What is the change in beam quality also referred to as?
“Hardening” of the beam
Inherent filtration is .5mm of what?
Aluminum equivalent
What is added filtration?
Consists of sheets of aluminum (or equivalent) of appropriate thickness
Where is the added filtration located?
Outside the glass window of the tube housing above the collimator shutters
What size should the added filtration be?
At least 2.5mm Al
In radiology, what is the metal that is most widely selected as a filter material?
Aluminum
Why is aluminum used as a filter in radiology?
- It effectively removes low energy (soft) rays
- Lightweight
- Sturdy
- Inexpensive
- Readily available
