Geometric Verification - Breast

Question 1

SGRT : Positioning

Answer 1

-position patient according to reference surface
-verivfy / adjust position w IGRT (2D,3D,MV,KV)
-Breath hold / Free breathing gating (confirming position of baseline and amplitude)

Question 2

Following set up what steps will you take before
acquiring an image?

Answer 2

-ask patient to confirm laterality
-the light field outline is on the skin
-SSDs (if not correct shifts could be out)
-Anterior coverage is adequate (daily check)
-posterior check

Question 3

Treatment Approaches – will guide your IGRT strategy

Answer 3

PHASE 1:
breast :whole or partial
nodal volumes: SCN or IMN

phase 2:
chest wall (mastectomy)
intact breast (BCS) target volume is based on clips

Question 4

OAR

Answer 4

heart
lung
spinal cord
brachial plexus

Question 5

scanning margins in CT

Answer 5

cover both lungs inferiorly for calculating DVH
no GTV
CTV is entire breast
PTV is adding a 2cm margin

Question 6

field borders:
sup
ant
inf
medially

Answer 6

-covering breast
-2cm due to swelling
-2cm due to mobility of breast
-midline , not covering contralateral breast

Question 7

Whole Breast - Wide field tangential

Answer 7

2D MV images

-field aperture is image - can see the MLC and field borders
-match in longi and vertical directions
-good for soft tissue match

Question 8

Partial Breast or more complex treatment planning techniques

Answer 8

2D KV orthogonal images
-match to clips as its more accurate than matching to bony match
-if no clips .. increase CTV-PTV margins from 5 to 8mm

Question 9

Supraclavicular treatment : Considerations

Answer 9

dual isocentric tx