how to set user origin

Question 1

What is it

Answer 1

FIRST STEP

telling where tattoos and skin are
do before beams as these co-ordinates define x.y.z of centre

Question 2

what does user origin look like

Answer 2

green plus

Question 3

how to set user origin

Answer 3

scroll trough slices and find fiducials
drag lines to markers
RC user origin and set it to intersectioning plans

Question 4

how to set isocentre to centre of PTV

Answer 4

-click on field and click align to structure
-click structure projection then PTV
-round coordinates

Question 5

what is reference point

Answer 5

representative of dose through out PTV

Question 6

if you want to normalise away from isocentre

Answer 6

-RC ICRU reference point—– new location for existing ref
- patient volume to PTV

NB IF BREAST, PATIENT VOLUME = BODY VOLUME

Question 7

creating a new reference point for breast

Answer 7

-RC reference points — new ref point and location
-call it test and make patient volume = body
-this will put ref point on isocentre

Question 8

ICRU50 tells us

Answer 8

-ref point cant be normalised at beam edge (as this is where the isocentre was when ref point was added)
-tf click arrow with blue x and move ref point perpendicular to isocentre

Question 9

if you want to make your new location of reference point your new primary ref point of the plan

Answer 9

change ID to test (done)
now you can calculate plan and normalize to new reference point