Radiation Protection And Dosimetry Flashcards
1
Q
What units is Absorbed dose measured in, and what type of effects does it effect?
A
- Gy (Greys)
- Absorbed dose is used to relate deterministic effects
2
Q
What unit is effective dose measured in, and what type of effects does it relate to?
A
- Sv (Sieverts)
- Effective dose relates the probability of stochastic effects occurring?
3
Q
What factors effect the uniformity of dose in CT?
A
- Patient thickness
- Scan Field of View
4
Q
What is Automatic Tube Current Modulation?
A
- Balances patient dose and image quality by altering the mA.
- uses the scout scan to to calculate the changes
5
Q
What are the types of shielding in CT?
A
- Bismuth
2. Lead
6
Q
Describe bismuth shielding.
A
- Used for anterior dose reduction
- In plane shielding
- Must be outside the SFOV for the scout scan, otherwise useless
- Effects ATCM
7
Q
Describe lead shielding?
A
- Enhances perception of safety
- Out of plane shielding
- Must be wrapped 360 degrees around the patient
- No effect on image quality
8
Q
What is over ranging?
A
In order to ensure that the entire area of interest is scanned, a scan will start slightly above the anatomy of interest and proceed below the anatomy.