Precisely!
Do you use Dmax 2 x 8.5 Gy for spinal cord?
What I have been discussing with colleagues is the target volume definition issue.
Contouring guidelines call for a rather large CTV. For example with a 1cm well lateralized lesion in the vertebral body you should still contour the entire vertebral body as a CTV and prescribe the dose to it.
Sorry for my bad MS Paint skills...
Green is GTV, you can make it bigger if you want to.
Red is the cropped CTV, I didn't add the pedicle here but you could probably add it to depending on how close the GTV goes to the edge of the vertebra.
View attachment 308900
Do you feel that the risk of microscopic tumor for example in the purple area which is something like 1.5-2 cm away from the GTV is high enough to justify that area receiving the full dose?
Wouldn't it be better to prescribe a higher dose to the GTV with a small PTV margin and then cover the rest of the CTV (as per recommendation) with a lower dose? In other words: why should macroscopic disease receive the same dose as microscopic disease? Could such an approach perhaps lower the risk for fracture.
Now, this is pretty "simple" case, where the lesion is well confined. Certainly in a bigger lesions involving most of the vertebra or when you cannot really see its boundaries well even with a good MRI, I understand that declaring a part of the vertebra as "uninvolved" may be difficult, but what about cases of small mets like this one?