Feature | October 13, 2006

With the introduction of recently FDA cleared MVision megavoltage cone-beam imaging package by Siemens Medical, Imaging Technology News (ITN) spoke with Andreas Schlatter, director of Marketing Development for Siemens Medical Solutions Oncology Care Systems, about the highlights of the first commercial implementation of cone-beam technology utilizing a standard radiotherapy treatment beam.
ITN: Could you tell me a little bit about the MVision megavoltage cone beam imaging package that was recently FDA cleared, and how the MVision package for adaptive radiation therapy improves accuracy?
Andreas Schlatter: The MVision megavoltage cone-beam package enables you to take three-dimensional (3-D) images of the patient in the treatment position. That means we are doing the imaging with the linac radar at the time when we want to treat the patient and we do it in a way that we take a series of up to 200 images, while the gantry rotates at about an angle of 200 degrees, taking regular low dose portal images.
Out of the 200 images we are creating, we calculate a 3-D image of the patient anatomy. With that we get not only the anatomy of the bone structure, but we can see soft tissue differentiation as well. This is, of course, important because you want to see exactly where the tumor is located or where the target is located in relation to your treatment so that when you start your treatment, whether it is an IMRT treatment or whether it is just a conformal treatment, you know exactly that you are hitting the target and sparing the healthy tissue.
The big difference is that now you are able to create a 3-D image, which, of course, gives you much better information about the location of the tumor and so you can really increase the patient positioning accuracy.
ITN: How fast are your competitors rendering 200 images?
AS: Well there is maybe a difference in a minute or so. You have to calculate the 3-D image and you have to acquire first the 200 images so it takes about 1.5 minutes until you see the 3-D image on the screen. The whole process from acquiring the image to getting the calculation done and how much you have to shift the patient on the table is done in less than three minutes with the MVision. I think this is really the fastest on the market, and, of course, speed is important.
ITN: The system has cone-beam technology utilizing a standard radiotherapy treatment beam. How is this advantageous to the user?
AS: I think there are several points. Number one, when using the treatment beam, that means we do not add additional technology like what the competition is doing with the kilovoltage imaging source and detector. No additional hardware is really required, so that is an effective and efficient solution.
There is a difference in the image quality using megavoltage instead of kilovoltage. When you have patients that have metal implants like teeth or hip prosthesis, megavoltage does not give you any artifacts. With the kilovoltage cone beam you get very poor image quality due to the metal implant. There are some clinical cases where the image quality is better compared to kilovoltage. Typically, if there is no metal, kilovoltage gives you at least as good of an image quality as megavoltage.
There are some pros and cons for each of the different technologies and we are saying when we talk about image-guided radiation therapy or adaptive radiation therapy, there is not just one technical solution for it.
The competition is working with kilovoltage cone beam; actually we do this as well. We have just introduced our megavoltage cone-beam solution MVision and we have some other solutions. We want to provide different technology for the different needs in the hospital.
ITN: How is MVision designed to complement a clinician’s oncology workflow?
AS: Part of our goal to ensure that this will be used in clinical routine is to implement or to include the whole workflow into the regular workflow. For our linacs, we provide one software, Encore, which is Coherent Software, and which supports the workflow during the treatment. When we designed the MVision megavoltage cone-beam imaging package, we included all these additional steps with the fusion and the calculation of the offset into that work flow, so it is still one monitor and one key vault and one mouse that you are using to perform all these steps. You don’t need an extra computer. You don’t need extra software. This all included in one workflow and I think that is important to customers.
ITN: Are you saying that any new technology has to be integrated into the workflow in order for the institute to really adopt it?
AS: Yes. Our philosophy from the very beginning when we started to develop the Coherence workflow solution was that all different applications and solutions, whether this is a 4-D gating or IGRT solution, has to be integrated into the software.
One of Siemens’ strengths is that we have one common software platform, whether this is at the linacs or for virtual simulation at the CT or treatment planning area.
ITN: What technology will Siemens focus on for the future of adaptive radiotherapy?
AS: We have several issues that we are working on right now. Number one, of course, is taking the next step with MVision, which is not only using MVision for imaging but for dose-guided radiation therapy to calculate the delivered dose to the patient.
From the technology point of view, we are working as well on kilovoltage cone beam in a little bit different way from the competition.

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