I am seeing such a wide variety of SCV breast prescriptions. What is everyone here using? I have seen 50 Gy in 25 with 6 MV to dmax, 45 in 25 to 3 cm, mix of 6 MV and higher energy, etc? wonder how SCV was prescribed in MA-20?
thanks
thanks
I am seeing such a wide variety of SCV breast prescriptions. What is everyone here using? I have seen 50 Gy in 25 with 6 MV to dmax, 45 in 25 to 3 cm, mix of 6 MV and higher energy, etc? wonder how SCV was prescribed in MA-20?
thanks
Does anyone still use Rx points anymore in this day and age of CT-based planning and 3DCRT?
So we use this philosophy and do things slightly differently. We start by contouring all our target structures including ICV/SCV. Planning starts with the usual half-beam blocked, monoisocentric technique for the breast with iso set at the bottom of the clavicular head.
With regards to the ICV/SCV field, the conventional teaching is the third anterior field prescribed to a depth as Gfunk just mentioned. This works fine for thin people, but as he mentions, you can only get in so deep with an anterior only beam.
So we do it in four fields, adding an opposed posterior beam to the conventional three field technique. Typically for the SCV fields, this is 6MV PAO/APO. This way we can achieve a homogeneous 50 Gy easily to the contoured nodal volume. Of course, it probably makes no clinical difference, but the plans look nice.
We'll treat to 50Gy if we can get it, but skimp down to 45Gy sometimes if needed for constraints. It depends on the circumstances. This most often comes up when doing elective IMN irradiation to spare lung and heart dose.