Validation, Commissioning and Early Clinical Results for Beam Guide – a Tool for Radiation Dose Visualization

Yeah. So talking about BeamGuide today. I’m a physicist in the NHS down on the South Coast. This is near where I live. It’s beautiful. So yeah, before we go on, some of you may not have heard of BeamGuide or seen it. So a picture tells a thousand words. It’s an enhancement postural video, and you’ve got this orange projection and the white outline, and it lets you see the beam in a new way. It’s the dose.

It kind of works in partnership with Dose RT. I’ll come back to this and go into more detail on that, but it’s just to get us all on the same page. I thought I’d start with an analogy, like a simile, to help us understand what this is adding and what Dose RT is as well. So we all, in our cars now, have this lane assist. So this is on your, we say motorway, but on the interstate, you’re keeping your vehicle in the right place. The position on the motorway is in that lane, and it’s watching the position and alerting you if the truck here goes out of position. And Dose RT and BeamGuide, there’s this whole new dimension. And it’s not just focusing on the position, but it’s the kind of consequence and the thing that really matters, in the case of this analogy, is the vehicle next to you. That’s why you need to stay in the right place in the lane, is so you don’t hit the vehicle beside you.

And Dose RT is a little bit like that and a bit more of a silly analogy. Of course, in the UK, we just have afternoon tea and scones and clotted cream and drink tea. But if you imagine you’re in this posh hotel, and they’ve set everything up and laid the cup out in front of you and placed all this arrangement in front of you and gone to all that care positioning that, but then they pour the tea into your lap or miss the cup and pour it on the table. That’s a bit like what’s happening if we’re positioning our patient on the couch, but then we’re getting the dose to the wrong place, and Dose RT and BeamGuide are helping us to get the dose to the right place as well as the position.

So a trip back in time. It wasn’t quite like this, but in 2001, SGRT was invented, and it’s come a long way in that 25 years. And alongside that, we’ve had massive changes in radiotherapy, haven’t we? We’ve gone from conformal treatments and the dose conformity’s got better and better. So that’s necessitated an evolution in IGRT as well. We’ve gone from kind of setting the patient up and hoping they stay in the right place. And then we’ve had, I’d say, cone beam imaging was the biggest leap because you’ve got internal anatomy, and of course, we still rely on that quite a lot. And SGRT is as big a leap again. And then I think Dose RT really is a whole new era as well because you’ve got the live imaging of, or visualization of the dose, and I’m looking forward to David’s talk next actually to learn more about what they’re doing at Dartmouth with that. But BeamGuide is kind of in partnership with Dose RT.

So normal AlignRT, SGRT, the conventional sense is completely widespread and standard of care now. It’s all over the USA and indeed the world, over 3,000 systems. But Dose RT is still smaller, a lot smaller compared to that. And some of the key events along the way since this 2001 invention, key events for BeamGuide is postural video in 2020, and then, of course, Dose RT kind of—and some centers were using it before that, but 2023 for kind of mainstream use.

So then now we come to BeamGuide. And in this workflow that we’re kind of familiar with, the VisionRT products across the patient pathway, BeamGuide is at this treatment and dose stage. The positioning of the patient, that’s where you’re really using it, and then you can keep an eye on the patient through the dose delivery. Of course, if you’ve got Dose RT, we don’t yet, unfortunately, you can visualize it while the beam is on, actually on the patient. So I keep referring to Dose RT, and I said it is kind of smaller use at the moment than AlignRT. But back in 2021, there was this first publication with around 60 patients, and then a few years ago, we had a much bigger study, over 600 patients. And then this year, a publication from Adi and his co-authors, more routine use, in Germany, a couple of centers in the US, including here, and a mix of Linacs. So there’s quite good evidence now for this, and as I’ve said a few times, BeamGuide is kind of a version of this.

So coming back to this view, kind of look at some of the aspects in more detail now. You have the white outline showing you where the beam should go, and then the orange is live updating on the patient’s position, where it’s going to go. So this CAAO phrase summons up images of the Mediterranean to me, but unfortunately, it’s not that use. Slightly more boring or dry use of the word, no beaches. This completed irradiated area outline is an important concept when we’re thinking about BeamGuide. I’m not sure if they coined the phrase, but I came across it first of all, in Varian Eclipse. You’ll recognize this if you’re a physicist analyzing PDIPs. So the CAAO is nicely illustrated. I’ve got a video on the next slide. Hopefully, it will advance.

So the CAAO is—this video is from VisionRT. If you get BeamGuide, this training video is excellent. So watching the MLC shapes move there, this one’s prostate VMAT, and then we had an IMRT breast field. The Chao is the sum of all of those kind of beamlets, the different control points. So if you’ve got the dynamic MLCs moving, you can’t just rely on the light field because the first position of the MLCs for a VMAT or IMRT is of course going to change, and they’re moving throughout the treatment. So that’s one of the benefits of BeamGuide over a light field. It’s showing you that white outline you can see on the patient there, is showing you the sum of all of those control points where the MLC positions are going to be. And this slide from Mike kind of addresses that question, too. I think I’ve probably explained it, but the light field’s missing quite a lot in this world of IMRT and VMAT. And you’ve got a nice video there from him of their DoseRT use.

So moving on to the kind of validation and commissioning. Last summer, a team from VisionRT came down to my center, and we did some film measurements. So this is gafchromic film. I’ve highlighted with the white lines there the irradiated area. And this view is actually from the central camera pod. When I’ve done film in the past, I’ve scanned the film and analyzed it in that traditional way. But we actually used this view from the camera pod to look at where the radiation was going on the film, and then compared that we had the irradiated area on the film and then the light field as you normally would. That’s kind of one of the classic physics tests. But now with the addition of what the BeamGuide projection, that orange mask is a filtered image there compared to the light field. And it had really good agreement, which was reassuring, and we did that for a bunch of different field shapes.

That was last summer. When we installed the clinical version at my center a couple of months ago, a colleague and I did some basic functional testing as well. So that last view was in Eclipse, and then we put deliberate errors on the position of the patient, or the phantom rather. This is obviously a breast field, and then we did that for pelvis-type fields as well. We are going to do some more commissioning measurements, but we actually wanted to kind of do some basic tests, but then crack on and use it with patients because the real important part of the commissioning, we felt, was to get that qualitative feedback from radiographers, therapists, and how they were finding it. So we quickly just brought it into use and moved on to it with patients, which is not the normal way we do things with new equipment, but we felt that was right for BeamGuide.

So this is from Adi, and he and Mike have done this because they have DoseRT. They can do, I think this one’s got a little video. So doing different projections on the BeamGuide and then comparing that with the various different shapes to DoseRT, and they had very good agreement when they did that testing. And it’s quite nice to be able to compare those two parallel and similar ways of viewing the dose.

So onto the case studies. I think that’s the most important part here, isn’t it? Is how it actually is with patients. So, this is a summary of our use of it at my center. Unfortunately, I wasn’t able to get permission to share the images. I’ve got lots of screenshots, and it’s quite a visual tool. But thankfully, Adi and Mike, and Florian have kindly shared some with me, so I’ll get onto them shortly. But we mainly focused on breast patients. We’ve done kind of 20 or 30, all different techniques, so classic tangents and then mini VMAT arcs and IMRT. And it’s been really useful for breath hold. Of course, the position is kind of that much more complex and critical because the patient’s moving into a breath hold position. Once or twice, we’ve had some issues with bolus. Just the shiny surface of the bolus has caused the projection, that orange projection, to get some holes in it, kind of. You can just turn that off, and I’ve got an example. I’ll save it for the illustration when I’ve got the image up. But the white outline is still really useful for bolus. And the key case studies I’ve put there, I’ll move on to.

As I said, this is an image from Adi. So it’s not the actual patient we saw it on, but it’s the same issue. Positioning the arm and those kind of gross body position stuff, postural things, are really good for BeamGuide. So a colleague of mine setting up a patient and the lady’s arm was in slightly the wrong position, and it hadn’t been picked up by the RTDs where the region of interest was. That didn’t catch it, and the postural video wasn’t really showing it, but he noticed the projection, the orange color wash on their armpit and was able to move their arm into the right place and get that projection inside the outline, which is great. This is another excerpt from the training video that I used earlier, and moving the chin is really affecting where the dose is going. And we’ve seen exit dose on patients that we’ve been treating, and we wouldn’t have previously been able to see that without the BeamGuide, and I know that’s been the case with some of the DoseRT centers. They’ve picked up on stray radiation, which they wouldn’t have got previously.

So this is, as I said, some examples from Adi. So on a pelvis, you can nicely see the color wash going all the way around. And here’s a video version. The lateral views are really nice with BeamGuide because you get a good angle on the patient, as you can see there. And it’s an added bonus to the postural video. And of course, postural video is such a game-changing feature. It’s great to have that, both the fields and updating where the patient is with the orange projection. And there, you can turn it off if you need to view where the orange part is covering.

And then for breath hold, as I said, it’s very useful. It’s just another piece of information to help you confirm that the patient is in the right place as they’re taking their breath in. And here’s that bolus example I mentioned. So if you look in the bottom right-hand side, you can see the bolus, and on the middle image at the bottom, you can see the orange projection is—actually, this is an older version, and it is better now. And I’m sure the next version will be even more so. But you can just turn off the orange projection and then actually use the white outline to make sure that your bolus is fully covering that chow, where the fields are going. So it’s a really nice way to check that you’re fully covering the entrance of the beams where the bolus is.

So this is from Florian, and it’s just a really good illustration of that gross body position. The patient’s obviously got their arm down on the left-hand side, and it’s shown so clearly with that orange projection. And then once they put their arm up, it’s perfect. It’s in the right place. And it just makes it very obvious to the therapists who are setting up the patient. And then here’s another breast treatment, this time a VMAT, and you can see with the red arrows highlighting that there’s a mismatch between the projection and the outline, and it just nicely shows that roll on this one, and then highlighting the lateral position on this one. You can see that the roll is actually within tolerance, so you might just think, “Oh, that’s okay, it’s green, I’m going to crack on.” And actually, no, we need to change the patient’s position a bit and fine-tune that.

And then, oh yeah, that’s the one with the roll. So here’s a lung patient, and they weren’t able to actually correct the position. It says the patient, their chin position couldn’t be moved, but actually, they were then, because he has DoseRT at Florian Center in Germany, they could monitor the patient’s position from fraction to fraction with that.

So that wraps it up, and there’s some conclusions there. Happy to answer questions if anyone has any, or you can grab me in the next break or tonight. Thank you.

 

 

 

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