Alan Pollack, M.D., a radiation oncologist at Sylvester Comprehensive Cancer Center in Miami, Florida talks about a new more precise way of delivering radiation to tumors.
Interview conducted by Ivanhoe Broadcast News in June 2016.
Tell me about this newest MRI guided technology for radiation treatment. First of all how long has it been around, let’s start there.
Dr. Pollack: The MRI device is called the View Ray meridian system and it’s the fourth unit in the United States, I think sixth worldwide. What it allows us to do is to take real time MRI images while we’re delivering radiation. We get a high resolution view of the soft tissues, most of the time we can see the cancer and we can see where—if it’s moving during the treatment. It’s really the only device that allows you to image in real time while you’re treating the patient with radiation.
What’s the advantage of that, of being able to see where you’re delivering radiation in real time?
Dr. Pollack: In radiation oncology there are really two main ways that we have made improvements over the years and that resulted in better tumor control and more cures and less toxicity. One of them is on the delivery side, new techniques to conform the radiation to the target. And the other has to do with the imaging in order to do that and imaging in treatment delivery. On our standard machines we use something called cone beam CT which is a CT like image, it’s very fuzzy but it’s revolutionized how we give the treatment to being able to see the target. But it doesn’t allow us to see the target during the treatment. There’s some other methods to do that but none that image greater than four times a second and which is what we have now in the View Ray system. It just allows us to use tighter margins to be able to more directly visualize the tumor and make sure we don’t miss it and to minimize the normal tissue that’s being treated. It’s a win, win, you get a better tumor control and less toxicity.
Are there any disadvantages to this system?
Dr. Pollack: It’s new technology so everything is more labor intensive and the software is a first generation. I would say that it takes longer to treat a patient so it’s more costly. But with every new technology like this we’ve seen that that’s the case and then over time there are less expensive ways of doing the same thing, costs come down and the speed of the delivery goes up. On our standard treatment machines, our treatments have gotten very fast using something called art based delivery which really didn’t come in to play clinically until about five years ago. As this technology becomes more popular I think we will see more development in the delivery as also in the dosimetry that we can achieve, that is how the dose conforms to the target and the speed of the imaging will improve. This means that patient throughput will then increase.
When did the technology go in to use?
Dr. Pollack: The first unit was probably a couple of years ago at Washington University, St. Louis, I’m not sure exactly on that but they had the first. The first unit was developed and put in there and tested. Then soon after that two other sites installed it and then we were the fourth site in the United States.
We started about two months ago, maybe two to three months ago.
What kind of results are you seeing?
Dr. Pollack: The images are spectacular. Yeah we see soft tissue resolution that it’s MRI resolution so it’s a point three five tesla magnet but the images are gorgeous. We can tell where the tumor is, we can tell each day if the tumor is shrinking to a degree that we’ve never been able to see before. The tracking on the system is really state of the art. What we can do is at least in one plain we can visualize the tumor during the treatment. We can set a boundary around it and if the tumor moves outside of that boundary by a certain percent let’s say we set it at five percent and six percent of the tumor moves out that boundary it will shut itself off automatically. This is incredibly valuable to us because as I mentioned before we can shrink the margins that we have to place on the tumor for uncertainties so this reduces uncertainties in treatment delivery.
Have there been any studies to quantify the benefits of this system?
Dr. Pollack: It’s brand new and all I can say is that every time we’ve made an advance like this in either the ability to deliver the radiation in a more tightly controlled way we want ability to image so that we reduce uncertainties. We have seen benefits so control rates go up. It’s really all about dose and volume for us, getting the dose where we want it to get and reducing the volume in the normal tissue that see the higher doses so that we keep toxicity low. This unit allows us to do that. It addresses those problems directly.
When you talk about toxicity what kind of damage might we expect in the surrounding tissue?
Dr. Pollack: For example for abdominal and pelvic tumors, we have bowel, bladder, liver, things like that that can be damaged from the radiation. This will allow us to minimize that. For moving sites like lung and liver it allows us to reduce the amount of normal lung that gets treated or liver. There are certain tolerances and by tracking and only turning the machine on when the target is within a certain window we can minimize the normal tissue doses and the result in toxicity.
Who is a good candidate for this kind of therapy?
Dr. Pollack: I would say most patients are good candidates. We are being selective because it takes us longer to treat but moving targets especially. I mentioned lung and liver, pelvic tumors, recurrences where we need to see the normal tissue anatomy more clearly and make sure we avoid previously treated areas. The other thing that it’s very valuable for is something called stereotactic body radiotherapy where we give very high doses in fewer fractions, one to three fractions. Treating in the abdomen and in the pelvis or in the chest with these very high doses which have been shown to be more efficacious we really have to be careful that we don’t miss the target and that’s where this technology comes in.
Is there anything that you want to say that I did not ask you?
Dr. Pollack: I think one of the things if I could just give you a little background, maybe there’s a snip that you might use from this is that we’re very vested at the University of Miami in imaging technology in the Department of Radiation/Oncology. We have NCI funding on how to use something called multi parametric MRI and so we’ve been developing methods to better use imaging and how we plan and treat patients. This is a natural step for us and it is to adopt MRI in the treatment paradigm by applying it during the treatment. There’s a lot of research that will go on regarding how to use this device and how to use the MR images that we get from the device every day to enhance our ability to better control tumors and minimize side effects.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Patrick Bartosch
Patrick.bartosch@med.miami.edu
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