Posted by Windfall, a resident of the Old Mountain View neighborhood, on Jan 13, 2011 at 8:32 pm
Kudos to El Camino Hospital for: (1) keeping up with the latest medical device technologies; (2) sorting through the often confusing and distorted claims of the various device manufacturers; and ultimately (3) bringing CyberKnife to their patient community.
This is a great story both for the Stuetzles as well as El Camino Hospital. Many others, however, have not been as lucky as the Stuetzles.
A recent expose in the New York Times underscores in horrific detail what the data has shown for some time now. Gantry-mounted machines – all of which have the design limitation of only being able to fire from within a single plane - are neither designed for nor safe nor appropriate for stereotactic radiosurgery (SRS).
Varian has a large installed base and the political clout that goes with it. They have been able to use their “research grants” and other lobbying efforts to manipulate multiple Certificate of Need processes as well as CMS code designations and ASTRO positions and thus delay the wider adoption of competing treatments; however, they have one major problem. Their basic technology is inferior perhaps even obsolete and new advances in imaging technologies are beginning to make this fact ever more obvious.
The basic problem is that all of Varian’s various radiation devices (various meaning in reality various marketing names) rely on large, heavy linear accelerators that are mounted on large, heavy gantries and therefore are only capable of moving (essentially rotating) around a single plane. This allows their radiation devices to fire at a target from two to seven different angles or directions.
Accuray Incorporated (ARAY) has introduced a proprietary miniature linear accelerator which is small and light enough to be incorporated into a robotically controlled system which allows their device (the CyberKnife) to fire at its target from 100 to 200 different angles or directions.
Accuray has moved radiation delivery from a two-dimensional paradigm into a three-dimensional one.
Why is this important?
To understand why this is a game changer you first need to understand just a few basics about therapeutic radiation.
First, with a sufficient dose, any living tissue can be destroyed. Put enough radiation on it and it dies. The trick is: how do we get enough radiation on the target without burning a hole through the patient.
Second, there are critical structures (such as the spinal cord, the chest wall, the bladder, the optic nerve, etcetera) which you need to avoid altogether.
Third, there are always toxicities associated with therapeutic radiation; therefore, minimizing doses to healthy tissues (and avoiding critical structures) is always important... at least to the patient if not the doc.
Fourth, radiation passes completely through the body. A beam fired from one angle will penetrate the body and go in one side and out the other. The reason the tumor (or other target) is destroyed is because it gets a higher dose than surrounding tissue due to the cumulative effect of multiple convergent beams.
Here is where CyberKnife’s competitive advantage becomes quite apparent. Just to keep the math simple, if we have five beams converging on a target and each beam fires 5 Gys, in one session we can drop in 25 Gys on the tumor while the surrounding tissue will receive a dose of only 5 Gys.
But now what happens if we can fire from 100 angles? Again, keeping the math simple, we can now drop in 25 Gys with beams holding a dose of only 0.25 Gys. Thus the radiation delivery “drop off” is greatly enhanced and the surrounding healthy tissue is spared. The greater drop off also allows CyberKnife to effectively attack tumors located proximate to critical structures.
Further, Accuray has leveraged its three dimensional capability to develop a system that tracks, detects and corrects for tumor movement in real time. This feature is extremely important because extracranial tumors move due to respiration, gastrointestinal processes and other factors.
Varian, true to form, has lifted Accuray’s press releases (in some cases word for word) and claimed that its TrueBeam (trademark of the month) system can also track for tumor movement.
They are playing the investment as well as medical community for fools.
Obviously, a device which itself is only capable of moving in two dimensions cannot possibly correct for tumor movement which occurs in three. Nevertheless, this is what Varian management has claimed and continues to claim and will continue to claim until some analyst on some quarterly conference call wakes up and goes, “Hey, wait a minute…”
New diagnostic software is being introduced that allows MRI images to be read in such a manner as to predict the occurrence and location of microscopic disease that could not otherwise be seen or located. Dr. Don Fuller (San Digeo) is already using these images to create customized radiation treatment patterns using CyberKnife for prostate cancer in both stereotactic radiosurgical (SRS) and intensity modulated radiotherapy (IMRT) treatment modalities.
This is the future of cancer imaging and treatment, i.e., greater accuracy and precision both in the imaging and treatment phase. But only Accuray’s CyberKnife has the accuracy and precision necessary to take advantage of this new imaging data.
Varian is still attacking tumors with 1950s style gantry-mounted radiation sprayers and are so far behind Accuray’s trailblazing development curve that they don’t even have a miniature linear accelerator much less a robotic guidance and control system to put it in.
Varian shareholders tout proton therapy as the next development in radiotherapy. Proton therapy does have the advantage of having the beam release most (though not all) of its energy before passing completely through the body; however, that beam still needs to be aimed at its target and multiple beams still need to be converged on the target. Since Varian’s proton beam devices are also gantry-mounted, they still bring with them all of the limitations inherent with 2D treatment plans including the obvious inability to compensate for tumor movement that occurs in three dimensions with a device that only moves in two.
A lot of Varian shareholders make big noises about Dr. John Adler (the neurosurgeon and Accuray founder who had the initial idea to liberate the radiation source from the gantry) joining Varian as VP Clinical Applications. What they are missing is that while Adler provided the initial concept for CyberKnife, he never had (and still doesn’t have) the technical background or genius to actually build a gantry-mounted system much less a robotically controlled one.
That distinction belongs to the late Dr. Russell Schonburg who invented the miniature linac, Dr. Joseph Depp who designed the three dimensional guidance system, and Dr. Mohan Budduluri who combined Dr. Schonburg’s linac with Dr. Depp’s guidance system and actually made the thing work. And all that was years ago. Today’s CyberKnife is a highly evolved and advanced robotic system which is so far ahead of Varian’s gantry-mounted systems as to have a technological mote which is insurmountable in even the distant future.
The bottom line here is that Varian has a huge advantage in terms of installed base and docs and hospitals with vested interests tied to that base.
Accuray has a huge technological advantage which, at some point, Varian’s campaign of obfuscation notwithstanding, is going to become obvious to everyone including the patient community.
When that happens, who is going to want to be treated with a gantry-mounted radiation sprayer?
El Camino Hospital is leading the charge into more accurate, more precise, less invasive, more effective radiotherapy and the big winner is the patient community.
Not every hospital, however, has the same level of integrity as El Camino. There are more than a few horror stories out there. None of which should be happening. For more, see: