lung demo

Question 1

energy=
isocentre=
normalization=
beam=

Answer 1

6-10
centre of PTV
unlikely at isocentre
ant, lat oplique ,post oplique

Question 2

large PTV

Answer 2

no. of fields to get adequate dose conformity and low dose to lungs

Question 3

fields

Answer 3

5
add collimator straight away
start of beam can only enter through effected lung

Question 4

futhermore

Answer 4

-RC any field and align field isocentre group to PTV
-round pff xyz
-add MLC x=1
-maybe wedge on ant and post (start w midrange)

Question 5

to check if isocentre satisfy ICRU 50

Answer 5

RC field
move viewing plane to isocentre

Question 6

then

Answer 6

calculate plan
normalize to field isocentre

if max and min not good
add a new reference point (norm pt) and make it a primary
-move the norm pt to the isocentre
-move norm pt to 100% isodose line but as close as possible to isocentre
then normalize to norm pt

Question 7

look at DVH

Answer 7

D100 of PTV should be greater than 90

Dx= y axis (ratio of total structure)

if still less than 90% increase MLC on inf+sup borders

Question 8

to increase MLC aperature

Answer 8

click top right screen
change to beams eye field to a field
click MLC on LHS
if MLC moves out of field, move the jaws so it covers aperature