The Linac 2! Flashcards
1
Q
What does FFF stand for?
A
- Flattening filter free
2
Q
What are the advantages of FFF?
A
- It is more efficient, it is not being attenuated
3
Q
What is the role of the ionisation chamber?
A
- It shuts off radiation when desired MU are reached
- It contains a feedback mechanism to other parts pf the machine involved in beam production
4
Q
What does the ion chamber consist of ?
A
- Thin parallel plate chambers - which monitor radiation doses in electron therapy mode
- Two separate channels - just in case one fails
5
Q
What does the feedback mechanism from the ion chamber do?
A
- It alters the current to the steering coils to restore beam symmetry
6
Q
How does the light field system work?
A
- A mirror reflects light from a bulb
- The light is projected along the beam path
- It diverges the same as the photon beam
- It can show the radiation field on the patient surface
- Will show MLC position and field size
7
Q
What is a mylar mirror?
A
- A very thin mirror used to bend the beam
