What are your dose constraints for SBRT pancreas (absolute and relative) when treating with 5 fractions?

We contour duodenum, other small bowel, and stomach separately and for each allow V33 < 1cc and max 0.035 cc < 36-38 Gy. We will sometimes also add a 3mm PRV for these organs (if close) and try to keep this v35 < 1-2 cc. Of note, some protocols allow for higher dose to these structures...but on protocol for now.

Our other UTSW institutional 5 fraction metrics are (these are usually not tough to meet, unless need to make big expansion):

Esophagus - V32.5<5 cc, max 0.035 cc < 38 Gy

Colon - V32.5<20cc, max 0.035 cc < 52.5 Gy

Kidney - at least 200 cc less than 17.5 Gy

Our most commonly used SBRT fractionation off protocol is 40 Gy in 5 fractions to the tumor + tumor vessel interface (including vessel a few slices above and below tumor) with a 2...

I use a similar approach to Dr. @Dr. First Last.

We deliver 40 Gy in 5 fractions to the GTV + TVI. The pancreas and an elective nodal volume get 33 Gy in 5 fractions. A PTV-eval is created cropped 2mm from all bowel structures for planning the 33 Gy volume.

I deliver pancreatic SBRT with the CyberKnife system so interventional GI will place fiducials via EUS. I typically need 4.

All my patients are simulated and treated NPO for 4 hours. They all get SL Zofran 1 hr before treatment and I put everyone on a PPI before treatment starts, continue daily for 6 months total.

Constraints are as follows:

PTV40: V40 >= 100%

PTV-Eval 33: Dmin >29.7 Gy

Stomach:

Dmax < 35 Gy

V26.5Gy < 5 cc

Duodenum

Dmax < 33 Gy

V18.5Gy < 5 cc

V14.5Gy < 10 cc

Jejunum/Ileum

Dmax <...

We have a Varian Truebeam with RPM so I've been treating and utilizing an exhale-breath hold technique with fluoroscopic visualization of fiducials during RT. As above, NPO 4 hours before tx.

During simulation, I obtain multiple exhale breath hold scans to contour my GTV, TVIs, and OARs described above. Similar technique is described in Colbert et al Adv RO 2018 except, I decided to use exhale (rather than comfortable inhale technique) due to potential OAR sparing benefit noted on exhale breath hold. I'll also obtain a 4D-CT scan as a safety precaution in case patients can't consistently hold their breath.

I've been using the constraints recommended in the recent PRO paper for SIB-IMRT from the MR-Linac consortium. They also outline SBRT se...