Thank you for this. I have some experience in breast DIBH, but none yet with lung SBRT. Would you please elaborate on the process for CBCT couch shift if the ISO is too far off axis? My thoughts (without any experience) to ensure we don’t VRT any errors back to zero is as follows: set up to FB as close to all zeros as possible. Then set up to BH all green (minor shifts allowed, too large of shifts require re-set up). In order to shift to CBCT ISO and not lose valuable positioning data, would we BH to all green then shift to CBCT ISO while still in that BH and acquire a new VRT? Monitor new green on BH VRT at CBCT ISO during imaging and image analysis. Then repeat the process to go back to treatment ISO: BH VRT to all green at CBCT ISO then shift to treatment ISO with applied shifts from CBCT marching while still in BH and record a new VRT. Then this newest VRT is used for treatment. Does this sound reasonable for necessary shifter CBCT ISO?
Would it make more sense to plan the king sbrt with an isocenter not inside the GTV so that no shift is necessary with CBCT? That way the alignrt wirkflow is less prone to missed and hidden errors with VRT!
last question: lung sbrt patient with hands over head. Patient DIBH is predominately from stomach (chest doesn’t move much—this if your tracking region is on the chest wall and ribs, BH is not much different from FB. What region of interest in alignrt would you use for a patient like this, ribs + belly
thanks for your help! If you know of any good papers or videos on starting an sbrt program with alignrt, I would love to know! I just changed hospitals last week. I previously used only breast but will soon need to use alignrt for other sites with my new position. Thanks!