Chestwall (6MV & 18MV):
This patient had a malignant neoplasm of the left breast and came to our department after a post-mastectomy to receive radiation to the left chest wall (bolus QOD), SCF, IM nodes and PAB. This was followed by a chestwall scar boost of 9Gy for a total dose of 59.4Gy.
Composite plan to 50.4Gy.
Composite DVH to50.4Gy
I used a mixed beam technique: 6MV and 18MV. Typically, the 18MV beams are open or a wedge may be added to the lateral tangent. I try to never weight the 18x beams above 15% each. The SCF field has the collimator at 90 degrees. This enables me to do a field-in-field technique on the SCF inferior border region which becomes hot from the contributing scatter of the tangent fields.
This is a screen shot of the pre-merged field-in-field technique. The sub field, on the right, is weighted 10% to remove some of the inferior hot spot.
This is a screen shot of the pre-merged field-in-field technique. The sub field, on the right, is weighted 10% to remove some of the inferior hot spot.
