Optimizing Prone Breast Simulations and Treatments

Good afternoon, everyone. I’m just going to start with a quick introduction of who we are and where we work. My name is Gabrielle Arras. I have been a radiation therapist for six years. And my name’s Danielle Lamachko. I’ve also been a therapist for six years, and I’ve been the lead for almost two. And I just want to point out these slides were very beautiful and aesthetically pleasing, and it did not transfer over. So bear with us. We’re going old school, black and white.

We both work at Stanford Hospital in Stanford, Connecticut. We are a small community hospital, but we are in collaboration with Brigham and Women’s Hospital and Dana-Farber’s Cancer Institute out of Boston. We run on two TrueBeam Linacs, one Toshiba CT sim. We have about a 30 to 40 average patient load, and we are a completely markless center.

Today, we’re going to walk you through a practical step-by-step approach on using Aligner T to set up a prone breast with a focus on workflow, troubleshooting, and some key techniques to get your positioning right.

So, we all know that prone breasts can be a struggle nearly everywhere, so much so that some centers avoid it altogether. But we do feel like it does offer some key benefits, especially for women with pendulous breasts, that we feel like it’s really worthy keeping it as a treatment option. And to be honest with you, a few years ago, we were also in that struggle phase. We found ourselves taking multiple port films daily, having to reset up patients, sometimes even re-sim, so much so that we amended our imaging guidelines from weekly ports to daily CBCTs. And while that helped, definitely, it was not a magic fix. We were still having some setup issues, and our shifts were a little larger than we wanted to be, and it just wasn’t really up to our standard.

It really wasn’t until we went fully markless and we had to dive completely into the Aligner T to get our setups right, that everything changed. We got to a point where we see very minimal shifts. We never have to reset our patients. We never have to re-sim anyone. And our workflow is just so much smoother, so much faster, and we’re getting to a point where we want to go back to just weekly imaging.

We don’t have the vision product for CT sim, but I do want to walk you through our process anyway, because in reality, I don’t care how good you are at using this. If you have a bad sim, if you don’t have a good foundation, you’re going to struggle with your setup regardless.

So, some key considerations that we take into account when we are simming patients. The first thing is we like to pull the arms really forward, like almost straight. And we do that because we find that it makes it harder for the patient to tense themselves up and prop themselves up like this. Reproducing a relaxed patient is much easier than reproducing a tense patient. We use this fun little spa cushion that just makes our patient more comfortable. They don’t wiggle around as much. For the rib placement, on our board specifically, if they’re too high up, the bottom of their rib tends to hook right into that inferior aspect of the board, and they are super uncomfortable. They’re always moving around, and they’re tensing their shoulder. So we like to pull them down, so their rib is kind of sitting on top of that.

The lateral placement of the breast, we like to do about two to three fingers between the board and their breast tissue. If they’re too close to the board, you’re going to compromise some medial coverage. If they’re too far away, the patient can start to roll a little bit more in that direction.

The tabletop measure is actually really important because if you get too high and too close to that gantry with your tabletop, your ROI is going to be compromised because the cameras can’t see it. So for our center, it might differ for everyone else. We found that keeping it at 20 or above is kind of the sweet spot there, that we can always see the entire ROI. We don’t have to drop and capture an SGRT. Everything just flows a lot more smooth, and then we try to stick to that tabletop throughout the entirety of our treatment.

And then last one is just to minimize tissue variation between therapists and your sim and your treatment. We like to have everyone just pull the tissue down under the breast to smooth out that belly fold underneath. We like to look underneath with a mirror to make sure that that breast tissue isn’t actually being tugged towards the contralateral side. We pull it out to make sure it’s hanging freely, and the contralateral breast has to always be pulled out laterally and inferiorly. If every therapist does that the same way, your variance is going to be a lot smaller. I’m going to throw it over to Danielle. She’s going to go over how to draw an ROI, how we do our V-sim day, and how we troubleshoot a difficult patient. Thank you.

Okay, so drawing the ROI. It’s been said many times over the last two days that Aligner T is an amazing tool in our toolbox, but it’s only as effective and efficient and accurate as a well-drawn ROI. So, the first thing we’re going to do is ask our planning team to include the prone breast board itself in our body structure set here. And the logic behind that is it acts as another way to verify that the patient and the board are where they were at time of sim. So, I’ll try not to mess this up.

So we found through trial and error that the best ROI for us is a horseshoe shape. So you’ll see here we’re just going to draw a big U on the patient’s back. We like to rotate here, extend down to about midline on each lateral side, and then we also like to include the shoulders pretty high up. And this just adds some topography since a patient’s back when their arms are forward is pretty smooth. It might be a little difficult for AlignRT to determine what it actually is looking at. And then you’ll see here, once we have that ROI all set, we’re going to name it, and then we’ll just rotate that structure 180 degrees. And the snapshot here that you see, that’s another reason why we want that prone breast board included in the structure set. We’re going to use this to mimic that lateral placement of the patient on the board every day before treatment.

So these are just some tips to keep in mind. It’s also been mentioned multiple times. Just because you start with an ROI doesn’t mean it’s set in stone. You don’t have to be stuck with that throughout the entire treatment course. If something’s not working, always feel free to change it. So this is just an example of how the gantry, you can see in that yellow circle, it was blocking a very small portion of our patient’s back, and it wasn’t interfering with the ROI at all. So we just left it as is. That won’t always be the case, so you may need to shave it or just alter the shape entirely so that it works and that the cameras can really see the ROI from all angles. And then another tip that we personally have found very helpful is if you plan on capturing an SGRT reference, you may want to place a piece of paper or just a plain pillowcase on the board underneath the patient’s breast. And that just acts as a blank background so that when AlignRT captures that screenshot or that reference, it could just very clearly define the affected side breast tissue contours.

So VSim day. This is the day we want to really take our time, work out any kinks, and just see the whole picture, and set you and your patient up for success throughout their whole treatment course. So the first thing we’re going to do, we’re going to get the patient on the prone breast board. We want to clinically straighten them. You want to try to have their arms relaxed forward. If they have any skin that’s bunching up, try to smooth that out. Your partner’s going to pull out their contralateral breast. We pull it out in inferiorly just to replicate what we did in the sim. And then lastly, we’re going to grab that mirror. We’re going to rotate the structure set 180 degrees and just really try to mimic that lateral placement on the board.

So once that is all set, we’re going to drive the table up and in. We’re going to go to our tabletop vertical as well as the longitudinal. You can see here, you can use the contours on the prone breast board as another way to verify. So in this case, we’re driving that table up and in. We’re going to match the lateral so that the delta and the contours are aligned. And then we’re just going to start putting in the work to get the deltas and the contours to fully match. So in this case, we notice our longitudinal and our pitch are both negative, so we want to pull that patient down, and we can see the board is exactly where it’s supposed to be. So we wouldn’t want to drive that board.

So now we’re just looking at all the contours, making sure we like how everything looks. We’re going to notice that her breast tissue isn’t quite lining up to that contour, so we went in, and we just tried to pull it out more laterally. At this point, our deltas are all looking pretty close. We’re going to ascend to couch. And then you’ll see that the deltas and the contours are all in sync. We’re happy with that. So we’re going to check our lateral SSD. That is always the last step before we leave the room to image. I went too fast. All right, so we’re going to check the SSD here, and we’ll see that it is on the right lateral setup. We’re only a millimeter off of what it’s supposed to be. We’re very happy with this. We’re going to step out and do our imaging.

So here you’re just going to see in comparison the pre-shift versus post-shift. We do a daily cone beam for our prone breast patients. So this is with no shifts applied. Really doesn’t look too bad. And then this is after we applied some small shifts. I’m not sure if you can see the numbers, but all of our vertical, longitudinal, and lateral are below 0.3 centimeters, and all of the rotation, pitch, and roll are less than two. And you can see both of these images are very acceptable.

So that was an example of the potential of what a prone breast can be. I understand they are not always that easy. So on the contrary, I’m going to show you a more difficult and challenging patient setup and how we went about troubleshooting it. So in this particular patient’s case, you can see her deltas and her contours are all looking very good and spot on. But when we proceeded to our cone beam, for the first couple of days of her treatment course, she did have some large lateral shifts. At our center, a large shift typically is over half a centimeter. So we applied those shifts to try to solve this issue. We captured a permanent SGRT reference. But unfortunately, in the following days, we still had the same issue. And this is just a video. You can see our cone beam. Everything looks good, but there is an almost 0.9 centimeter lateral shift.

So in our next troubleshooting attempt, we decided to go back to the CT sim reference. We did the normal setup to the deltas, setup to the contours until they match, and then we decided, let’s check the lateral SSD. The reason why we wanted to check this is because a prone breast is one of, or maybe the only area that we set up to where the ROI is not on the actual treatment site. So we’re very heavily reliant on the body contours and the postural alignment and the SSD. So you could see here, we got our SSD within 0.2 centimeters, but the delta on the lateral was way off. Because we trusted the SSD a little more at this point, we decided to leave the room and proceed to our imaging. That method we did for a few days, and our images looked decent, but we still weren’t happy with the fact that the SSD and the deltas were not in sync with each other. So on our third and final troubleshooting attempt, we decided to have some fun and have some alternate ROIs to experiment with.

So you could see here with that, I know it was a little quick, with the original left breast ROI, we had a really large lateral shift as well as a large roll. As soon as we altered it and went to this new ROI, our lateral and our roll disappeared. So you can see here, we basically just chopped off half of that horseshoe shape, and then we extended her affected side way down laterally past midline, and that was just to really capture the curvature of her body. And then here, this is us setting up in the following day to that new ROI. And we’re just going to kind of go to war with that rotation for a few seconds. We’re going to get there. During this process, we kind of became slight perfectionists. But you see there, the deltas are all green. Our contours were on. We’re doing our final step of checking the lateral SSD, and we got this patient within 0.3 centimeters. So we were happy with that, and we proceeded to our imaging. And this was our happy ending. We finally got zero shifts. So I will admit it took probably eight or nine days to get to this point of zero shifts. But for the remainder of this patient’s treatment course, we had zero shifts every day. So at this point, I’m going to pass this back to Gabby, and she’s going to go over some setup tips and tricks that we learned along the way.

Okay. So I think the main thing that I want to emphasize to you guys today is that when you are using a Line RT in general, but definitely for prone breasts, you cannot look at your deltas as individual adjustments. You have to see how everything works together. How does your longitudinal affect your pitch? How does your roll affect your vertical? How does your rotation affect your lateral? And then look at your postural alignment to see what it’s telling you. We’re going to start with everyone’s favorite, the dreaded pitch, and how we go about fixing that. All right. I’m going to play this, and if you can pause it immediately for me. Okay. So as you can see here, this all actually looks pretty good. But she does have a -1.5 pitch. And the pitch, if it is about 1.5 to 2, can really affect her chest wall. So we really do want to try to get that as low as possible. She has a little bit of a positive longitudinal and a negative pitch. You look at her body contours, that looks fine. You look at her arm, there’s a little bit of a gap there. So you can go ahead and play that again. So on this patient, all we’re going to do is we are going to go ahead and just move her arm forward, and you will see that pitch disappear. Okay. So then we’ll go ahead and put all that on, and we’ll step out of the room. For this next one, Danielle touched on this one a little bit. Negative pitch, negative longitudinal. As you can see here, you can be tempted to drive that. But then you’re going to be left with a little bit of a pitch. But if you just pull the patient down, both of those things will disappear.

Arms. Arms are maybe the most important part of a prone breast setup. It is going to affect your roll, it’s going to affect your rotation, it’s going to affect your pitch. And this next video is kind of my favorite on how you can’t look at your deltas as individuals. So I’m going to go play it. If you can just pause this for me one more time. On this video, if you look at this, you’re like, “All right, I’m going to move the patient up because my longitudinal is 0.86,” or, “I’m going to pull hips to the right,” or, “I’m going to try to physically roll that patient.” But if you actually look at what it’s telling you, if you look at your contours, her waist, her body contour is actually on. So she doesn’t need to move up. But if you go over– Oh, go back. Play that. Can you play that again for me, please? Okay. So just going to walk over. If you look over at her arm contour, there is a big gap on her arm. Right? So, on this case, again, all we’re going to do is move that arm forward, and you will see magic happen. There you go. Right? If you had moved that patient up, she would’ve been in a completely wrong place. You would’ve had all of your rotations still be a problem, and you’re like, “How do I go about fixing this?” So look at what it’s telling you. Don’t rush. Don’t just jump in and start moving in and out, left, right.

The kickstand. This is something that we just kind of coined as a different way of rolling a patient instead of just kind of going like this or going like that. That’s not exactly always what it needs. The kickstand is– I will play this video, is she has a little bit of a roll here, right? What we’re going to do, we’re going to use the arm as a kickstand, as a little bit of a prop-up to help hold that roll. So as you can see, I do that, I go over, I prop up her arm, and it’s going to roll her to the contralateral side. And this next video is much clearer. See that big roll? We’re going to go over, we’re going to pick up that arm, slide it up in that arm cup, and bring it back down. Disappears. Right? And Danielle touched a little bit about on this earlier, that the prone breast, I do think, is the only thing that we’re setting up for the back, essentially, but we’re treating the breast. So that’s, I think, the biggest reason why you can have a lot of discrepancies. I’m going to go ahead and play this one. This is a little bit of what we touched on earlier with the SSD. Right? So in this, you see the lateral was at zero, but our SSD was off by 0.8. So what we’re going to do in this case is we’re going to take our handy little mirror, highly suggest getting a mirror if you don’t have one already for your prone breasts. Right? Going to walk over, any minute now, and I’m going to look underneath to see what’s happening. Right? Why is my lateral and my SSD not matching? And in this case, I see that her contralateral breast actually has to be pulled out further. She moved too far over on the board. So we go ahead and make that adjustment. We fix everything else that needs to be fixed, and it’s going to take us a minute. So I’m just going to– Spoiler alert, we get it to about 0.2, and we walk out of the room and everything looks great. And this one also, you can pause that for me, please. Okay. What this one was, her deltoids were on, her breast contour was off. So once again, we walk over, I pull that tissue out, let it hang a little bit more freely, and then it allows us to make any adjustments, and then her deltoids and her contours also match.

This is a little cheat sheet that we made for you guys, if you want to snap a little picture of it to reference back of how to read your deltoids together. Good.

So moral of the story, do not be afraid of prone breasts, okay? Just take your time and make sure your patient is comfortable and that tissue is hanging freely. Make sure you have a good ROI. Don’t be afraid to change it. Make sure all of the therapists are on the same page. You follow a standardized procedure. You know how to fix issues that are coming up. Troubleshoot. We still struggle sometimes. You’re going to struggle. We’re going to struggle. Don’t give up. She showed you that you can go from a very difficult patient to a flawless setup. Right? Take your time. Right? Look at the whole picture. See the story that this wonderful tool is telling you, and then proceed with your shifting and movements. Thank you.