Lec #4 - Shielding guidlines

Question 1

What is the role of an RSO or RPO?

Answer 1

• RPO usually a physician (most hospitals have RPO instead of RSO)
• Anywhere imaging live pts (need an RPO or RSO)

Anytime you get new equipment or design new lab RPO/RSO needs to ensure safety.
Helps decide pre-set techniques – make sure they are in alignment with proper dose/alara.

Question 2

What is maximum radiation level for a controlled vs uncontrolled area?

Answer 2

control - 20 mSv
uncontrol - 1 mSv

Question 3

What is the primary barrier equation?

Answer 3

𝐾=𝑃𝑑2/𝑊𝑈𝑇

Where:
P = maximum permissible weekly exposure expressed in R/week.
d = distance in metres from the target to the primary area.
W = workload in mA-min/week
U = use factor
T = occupancy factor

K = exposure per unit workload at unit distance, in R/mA-min at 1 metre.

Question 4

What is the value of P for a controlled and uncontrolled area

Answer 4

Controlled – 0.04 R / per week

Uncontrolled – 0.002 R / per week

Question 5

What is the leakage radiation from x-ray equipment assumed to be?

Answer 5

air kerma of 0.876 mGy/h.

Question 6

From the primary barrier equation how would you determine the thickness of lead required?

Answer 6

Use the K value and graph of Primary barrier thickness to determine lead required.