What dose constraints do you use for the pulmonary vein, pulmonary artery, and superior vena cava for thoracic reirradiation after prior conventional fractionation to a central lung tumor?  

In my opinion, the best paper to address this is from Stanford University. The authors describe normal tissue toxicity after thoracic reirradiation. Various dose fractionation schedules were used for both the 1st and 2nd courses of radiation, with dose converted to conventional fractionation (2 Gy e...

After completing an in house prospective trial of SBRT boost (most frequently 650cGyX 3) to the residual primary mass in stage III lung patients who had already received 60Gy standard chemoradiation, we assessed doses received by the pulmonary vasculature in an effort to estimate the tolerated BED. ...

Re-irradiation of the chest has been specifically studied by MD Anderson in a 2018 PRO journal paper using Intensity Modulated Proton Therapy (IMPT).  81% of patients had centrally located tumors.  Based on their results and others, <120 Gy to great vessels appears to be reasonably safe...