There are cheaper solutions than surface tracking that you can implement very quickly in order to carry out DIBH-RT.
pubmed.ncbi.nlm.nih.gov
What’s the worry
I guess not much per se, but if no worry free breathing, why a worry with dibh? It seems like a shell game either way.
I would imagine the worry with DIBH is simply reproducibility from sim to table, and day-to-day; whether one were using IMRT or not, reproducibility is going to always be a worry if you put patient in “unnatural” positions eg like a breath hold.
We do a daily cone beam fwiw. Also re free breathing and arcs, I know people are making the comparison to lung. However, in lung, we do 4D scans to eval target motion, and can make asymmetric expansions, etc to account for it. We can't or don't do either in RNI. I'm already uncomfortable enough with a PTV_Eval (for instance, I crop in from the skin less in TN), but the concept of a PTV in free breathing breast arcs is a lot of looking the other way as far as I'm concerned. In the end, though, it's breast and it's probably fine.
Not being antagonistic here, but how do you account for it? Contour on the MIP?
One thing you mention piques my interest. Why do crop less from skin in TNBC? Is there any data to support that practice/more skin relapses in TNBC?
No reason I can explain other than the standard decision to err on the side of less-conservative with TN. Some of the trials I rely on allow for cropping of 2-5 mm for PMRT, so I do some of both. Fwiw, I generally just do 5 mm when doing WBRT, and I can't say any of this would've impacted your case, or impacts anything.
Totally. I usually use 5mm as well with the exception of skin involvement, obvious glandular tissue in that range, etc. I think it was just bad disease, but one never knows for sure. Thanks for your thoughts.
We’ll throw it on for skin invasion, inflammatory, etc. We add it after sim, either with 5mm super flan or wax if tricky anatomy. We’ve shied away from bolus for most routine cases now though
Weird that MHD doesn’t track well with LADI think we are still all recovering from Darby but it seems a few are relentlessly closing in on a decision!
I would guess there are probably independent toxicities: CAD, arrhythmia, pericarditis, CHF, ?immunosuppression -each likely has an avoidance structure and relevant DVH metric. CAD -obvious. Arrhythmia -anecdotally, afib seems more common with treating near the base of the atria. Pericarditis -probably a high dose to the surface. CHF/immunosuppression-would guess something like MHD
Precisely.
Why you guys all want to do same way? Efficiency for planners and physics ?
In a large dept such as ours, there’s something to be said about process safety with standardization. That’s something I do buy into.
Hard to make it work... Some people do sequential, some so dose painting, some like 60 for stage 3 lung, some like to do a little higher etc
What is the data driven argument for using it with skin involvement?
This is ridiculous !
Non-coplanar "inverse pyramidal" 4 field photon beam approach works well for the boosting. If 0° gantry (g) and 0° couch (c) are gantry pointing straight down and head of couch pointing at gantry, a 315°c/45°g 315°c/315°g 45°c/45°g 45°c/315°g beam arrangement has been my go-to for nearly two decades. Adjust as necessary to miss things you want to miss, or "translate" the whole shape in space and keep the shape but use different angles, etc. You can also play this as two 90° arcs from 45°->315°g at 45°c and 315°c (hopefully your dosimetrist swings the moving gantry in non-coplanar, non-cranial arcs away from the patient's head... that just makes me more comfortable). Although I can usually almost entirely miss lung with 3/4 of the static beams.
Evicore probs a lost cause
