Should density overrides for VMAT lung SBRT planning be utilized for small mobile tumors?
Recently, while planning a patient for lung SBRT it was suggested by the physicist that we change the density of the PTV to higher density to improve dose conformity and lower the dose in the normal lung. Is this a recommended approach for patients undergoing lung VMAT SBRT for small mobile lesions?
Answer from: Radiation Oncologist at Academic Institution
The following reference offers a word of caution: Zou et al, Dynamic simulation of motion effects in IMAT lung SBRT., Radiat Oncol, 2014 9:225.
This study calculated the magnitude of dose deviation which can be attributed to the "interplay effect" for both the target and organs at risk...
Answer from: Radiation Oncologist at Academic Institution
The paper referred to by @Kenneth Olivier is Xiao et ao, IJROBP, 2009, 73(4): 1235-1242
It actually showed that with heterogeneity correction applied, the percent of PTV receiving 60 Gy was reduced, largely due to the physical issue of not having so much depth of high density tissue in the ITV...
Comments
Radiation Oncologist at Mayo Clinic
Doh. Good point Brian. I was thinking of the iso...
Doh. Good point Brian. I was thinking of the iso...
Radiation Oncologist at University of Colorado School of Medicine
you are correct, Ken The isocenter max point dose...
you are correct, Ken The isocenter max point dose...
Agree completely. But Dr Olivier don't see a lot o...