Dr. Cori Cross (Host): This is Pediatric Insights: Advances and Innovations with Children's Health, where we explore the latest in pediatric care and research. I'm your host, Dr. Cori Cross. Today, we'll be discussing how non-invasive Gamma Knife surgery is transforming care for patients with brain tumors and arteriovenous malformations, otherwise known as AVMs.

With us today we have Dr. Bradley Weprin, who is the Division Chief of Neurosurgery at Children's Health and a professor at UT Southwestern. Dr. Weprin, thank you so much for joining us today.

Dr. Bradley Weprin: Thank you for having me.

Host: So, let's jump right in. What is Gamma Knife surgery, and how does it differ from traditional brain surgery?

Dr. Bradley Weprin: So, Gamma Knife radiosurgery is a particular form of the delivery of focused radiation. So, it's not actual surgery, it doesn't require a knife. Unlike traditional brain surgery where we may make an incision, take a piece of bone off, put bone back on, and make an incision, and directly operate on your brain, the gamma knife tends to deliver precise beams of radiation to an exact target within your head and without opening your skull. So essentially, there's no cutting. Recovery is much easier.

Host: So, would calling it Gamma Knife almost be like a misnomer? Like, it's almost like gamma laser.

Dr. Bradley Weprin: It is not even a laser per se. And it all really depends on what your definition of surgery is. Classically, people think that surgery is being cut upon, but it's not.

Host: Got it. So, you would have this type of surgery done and you would literally have no opening in your skin. The radio frequencies or the radiation-- I guess it's not radio frequencies, right? The radiation.

Dr. Bradley Weprin: Correct. It's focused radiation.

Host: So, the radiation is just like normal radiation. When we get treated for chemotherapy, it's just going straight through your body to a precise location in order to deal with either the AVM or the tumor.

Dr. Bradley Weprin: Yes, ma'am.

Host: So, does that mean that you're collaborating very closely with Radiology to be able to deliver this to the proper location

Dr. Bradley Weprin: So, the process or workflow for Gamma Knife radiosurgery is the collaboration of a radiation-oncologist, a specialist who treats individuals with radiation, and a proceduralist, in this instance, a neurosurgeon like myself.

Host: Got it. And so, my understanding is that this particular type of surgery specifically benefits patients with brain tumors or AVMs. Can you explain to us why that is?

Dr. Bradley Weprin: So, not everyone with an AVM or a brain tumor is necessarily a candidate for Gamma Knife radiosurgery, but those that we believe are, the main benefits are safety, comfort, speed of recovery. Patients generally go home the day of the procedure. There's no scar. And most can return to normal activities within a day or two.

Host: So, is this replacing, I would say, like traditional radiation? Or is this replacing traditional surgery for patients who, you know, would have a tumor in the past?

Dr. Bradley Weprin: It is both. Gamma Knife radiosurgery is a way of utilizing radiation to treat a specific problem and, in this instance, an arteriovenous malformation or an AVM. It's different from conventional radiation in that it's much more precise. It is different from surgery, because of its precision and because of the things that we just spoke of earlier, regarding the lack of making an incision in your scalp, your skull, and your brain.

Host: So, say, you had a tumor in your head. And obviously, the issues with that is, one, you have a tumor in your head; two, it's taking up space, right? So even if it wasn't a tumor, it's something that's taking up space. Will doing this type of treatment, when you do the radiation, it will shrink it? When would you need to use surgery instead? Like if you had something massive and you need to remove that because of the space-occupying lesion, would you be able to use this? Would this be something that you could use in that instead? Or in that case, you would have to go to traditional surgery?

Dr. Bradley Weprin: In those instances, when we are trying to more acutely address, the problem related to mass effect. So, acute weakness, sensory change, seizures, we would consider open surgery, resective surgery. But when a lesion doesn't respond to surgery, when a patient has comorbidities or issues that make surgery even more dangerous, or maybe it's in a location that's difficult to get to, radiosurgery may become an option.

Host: Could you walk us through, if a patient decides to go this route, what a typical treatment experience looks like from basically consultation to recovery?

Dr. Bradley Weprin: Sure. So, the typical Gamma Knife treatment experience usually starts with a couple of consultations between myself, my colleague in Radiation-Oncology. And sometimes even an additional cerebrovascular surgeon where we're considering open resective surgery for the AVM or whether we're considering radiosurgery.

But in any event, when you meet with each of us, we review imaging, we evaluate the exam and kind of discuss the different options. Now, on treatment day, the patient is generally, at least for AVMs, not for all tumors, but for AVMs, undergoes general anesthesia following which we place a frame to the skull. So, I affix a frame on your skull while you're asleep or while the child is asleep. And that's to keep the head steady. From there, we go to have an MRI, a high resolution MRI, to help localize the target. We then go to angiography where one of my colleagues performs a cerebral angiogram. Then, we take the patient back down to the radiation suite. During the next 30 to 45 minutes, the radiology images are imported into a computer software program that allows us to localize the target, whether it be AVM or the tumor. We create a treatment plan. The patient is then brought into the Gamma Knife suite where they lie comfortably on the treatment table and where the Gamma Knife delivers the radiation based on the plan, the map that the radiation-oncologist and I have created. And that treatment in and of itself takes anywhere from 20 to 90 minutes in general. The patient then goes to a recovery area where we remove the frame. They're allowed to wake up. And once they're awake and drinking, they go home that day. No hospital stay, no incision, perhaps a little fatigue.

Host: So, I've had patients before who have had to do both chemotherapy and radiation. And usually, the radiation isn't a one-time thing. They're usually going back and getting it repeatedly. This sounds like it's a one-time experience.

Dr. Bradley Weprin: It can be both. Historically, the Gamma Knife-treated individual's only one time, which obviously limits the amount of radiation that you can use, as well as the size of the target that can be treated. The newer Gamma Knife models have established means to be able to divide treatment so you can provide lower dose radiation treatments in hopes of lessening the risk of radiation to surrounding brain tissue. If you give that in multiple doses, then you can ultimately give a much higher dose. We will do that with some large tumors and some large AVMs. Our preference is to try to treat in one day if we can.

Host: So, I have a question for you. You bring up a really good point. So, one of the issues that we have with radiation is, you know, the sequela, what's going to happen to this patient down the line, what are we possibly inducing that they wouldn't normally have the risk of later. And you think about that a lot in pediatrics, because if the children survive, then they're going to live for quite a long time. And you don't want to cause other damage down the line. When you think about things like treating an AVM and a pediatric patient, does that come into play when you think about radiation versus traditional surgery?

Dr. Bradley Weprin: Absolutely. So, radiation can obliterate, kill almost any target in the brain. The problem with radiation is that it can do some damage to normal tissue while it's attacking the abnormal tissue that you're trying to treat. Gamma Knife Radiosurgery is unique in that it allows us to use radiation beams to treat with millimeter accuracy very small targets, and avoid treating or injuring surrounding brain tissue so we can deliver a strong dose of radiation to a target like a tumor or an AVM while minimizing exposure to the healthy brain tissue around it. And this precision ultimately reduces the side effects that you just mentioned and keep critical functions safe.

Host: That's amazing. So with all that being said, are there other innovations or research efforts underway to expand the use of Gamma Knife?

Dr. Bradley Weprin: Yes. And so, one of those just happened to be what I kind of mentioned was that previously, the Gamma Knife radiosurgery was basically a one-time treatment. Now, there are instances where we can, one, treat without the use of affixing a frame to your head, and we can fractionate therapy, which means we can deliver small doses at multiple treatments so as to give a larger dose of radiation that maybe we couldn't have done 10 years ago.

Host: Amazing. This might be not the right question for you as you're a neurosurgeon, but just as like a geeking out question, this sounds like amazing technology, is it being used in other areas? Like, are other surgeons sort of using this same type of technology for their areas of expertise?

Dr. Bradley Weprin: Sure. So, Gamma Knife radiosurgery is a form of what we call stereotactic radiation delivery. And again, that's just utilizing different modalities to deliver radiation in a very focused way. This all started in the brain, and it has now metamorphosized to other areas of the body to include pathologies, not just in your brain and in terms of the real innovators and the really bright people, those happen to be the radiation-oncologist that I have the opportunity to work with at UT Southwestern.

Host: That's amazing. And it's my understanding that Children's Health is the only Pediatric Neurosurgery program in North Texas that is using this non-invasive Gamma Knife technology.

Dr. Bradley Weprin: That is true.

Host: Well, we are very lucky to have you with us. Is there anything else you would like to add before we wrap up?

Dr. Bradley Weprin: With my colleagues in Radiation-Oncology, I think we're constantly trying to improve what we do with regards to our imaging techniques, the software, the different ways we deliver the radiation to make treatment more personalized and more precise.

Host: Well, thank you, Dr. Weprin, for speaking with us today. It was so educational, and I really appreciate your time.

Dr. Bradley Weprin: Thank you for having me.

Host: As you heard, Children's Health is the only Pediatric Neurosurgery Program in North Texas that offers non-invasive Gamma Knife technology. If you would like more information about the Gamma Knife surgery and the Pediatric Neurosurgery Department at Children's Health, you can go to childrens.com/neurosurgery. That's children.com/neurosurgery.

Thank you so much for your time with us today and to our audience for listening to Pediatric Insights, advances and Innovations with Children's Health, where we explore the latest in pediatric care and research. You can find more information at childrens.com. And if you found this podcast helpful, please rate and review or share this episode and please follow Children's Health on your social channels.