set isocentre to PTV

Question 1

for half block tecnhique

Answer 1

-2 field
-6MV
-approx even weightings
-similiar ish wedging
-collimator @ 90

Question 2

when do we introduce the segmented beams

Answer 2

if dmax is over 107% and we need to reduce in order to reduce hotspots

Question 3

how to create the segmented beam:
creating the isodose structure

Answer 3

-RC dose —– convert isodose level to structure. eg 109
-create structure from the % that you added , THIS CAN BE SEEN FROM CORONAL PLANE
-for better view , RC top screen —- beams eye view

Question 4

how to create the segmented beam:
shielding out the new structure

Answer 4

-copy and paste field and name it segment
-go into properties of segment–> geometry tab
-tick asym x and apply
-drag jaws down to remove the new structure from the field

Question 5

final things to check

Answer 5

-ICRU cant be under 2cm from beam edge
-lat seg will have v little weighting
-less than 110% is standard for breast planning w/o PTV
-monitor units must be over 20 MU for segment beam.