Static Junctions Flashcards
1
Q
What is a mono isocentric technique?
A
two beams are matched at a common isocentre with both beams having a zero jaw at the junction
2
Q
Advantages of mono-isocentric techniques?
A
- Eliminating beam divergence
- eliminating the use of heavy cerrobend blocks
- ease and reproducibility of set-up
- obtaining the ideal match line dose distribution at the abutting fields
3
Q
Disadvantages of mono-isocentric techniques?
A
-uncertainty in dose at the junction region (therefore do not put junction in high risk area of disease) (+/- 5-7%)
(overcome with one common field for both areas and also having a junctioning set of fields)
-limited to max field length of 20cm
4
Q
What are the common areas that use mono-isocentric techniques?
A
breast/ chestwall with SupraClav +/- nodes
Head and Neck (though IMRT used more commonly)
5
Q
Why should we allow a 1cm tolerance for the jaw size?
A
