by Gus Iversen
, Editor in Chief | February 24, 2015
From the January/February issue of HealthCare Business News magazine
One such study is entitled, Comparison of Plan Quality and Delivery Time between Volumetric Arc Therapy (RapidArc) and Gamma Knife Radiosurgery for Multiple Cranial Metastases, and was published online and in the October 2014 issue of the journal, Neurosurgery. That study, conducted at the University of Alabama, illustrates drastically reduced treatment times for the latest VMAT-capable linear accelerators.
The study also indicates equivalent conformity and moderate iso-dose spill between Gamma Knife, Novalis, and TrueBeam. However, it is noteworthy that the Gamma Knife in the study is a Leksell Model C, which is an older model than the current Perfexion.
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The capability to deliver 2400 monitor units per minute means giving a dose 3 to 6 times higher than competing technologies, says Schulz. In the case of Henry Ford Hospital, the combination of throughput, accuracy, whole-body versatility, and positive clinical outcomes with Varian’s Edge has been invaluable to their practice.
With the brain in mind
Like Gamma Knife, the CyberKnife was designed for treating intracranial lesions. David Schaal, senior director of clinical publications at Accuray says, “From the start, John Adler, the inventor of CyberKnife, wanted to design a device that would be able to deliver many beams of radiation from multiple non-coplanar angles around the patient, but without a head frame.”
He says the company achieved that goal with the implementation of their robotic, motion-sensing system. To get a better understanding of the CyberKnife’s capabilities we spoke to a physician from Stanford Health Care, where they have a Varian TrueBeam linac as well as two CyberKnifes, and perform stereotactic radiosurgery in an average of 2.5 fractions.
In favoring X-rays over gamma rays, Dr. Steven Chang, a neurosurgeon at Stanford Health Care, points to the evolution of the machinery. “A lot of radiation oncology machines now use image guided tracking,” says
Chang, “It has sort of become a de facto standard for radiation delivery compared to older methods using rigid immobilization.”
Chang believes that for treating certain indications, some radiation delivery devices do not have sufficient accuracy. “The primary two machines that have an established long term track record regarding sub-millimeter accuracy are Gamma Knife and CyberKnife,” says Chang, who also points to trigeminal neuralgia as a disease that should specifically be treated with those platforms.
Chang says that with CyberKnife you have many of the benefits that are associated with linacs: you can treat the entire body, you can break up treatment into multiple fractions, and you can treat infants who have soft skulls. In weighing the benefits of CyberKnife over Gamma Knife, Chang says it’s in the lack of head frame and the option to treat the entire body.