Cyberknife VSI, one touched recently, another about to be...

The CyberKnife® Robotic Radiosurgery System (Accuray Incorporated, Sunnyvale, CA, USA) has undergone almost twenty years of technical development from its conception (1) to its most recent version, the CyberKnife VSITM System, the first of which was installed in April 2010. The CyberKnife System, as described in a series of technical papers in the late 1990s (2-7), began as a frameless alternative to existing stereotactic radiosurgery systems such as the Gamma Knife (Elekta AB, Stockholm, Sweden) and conventional linear accelerators (LINACs) equipped with head frames and stereotactic beam collimators. In the original CyberKnife configuration, a LINAC mounted on a robotic manipulator delivered many independently targeted (non-isocentric) and non-coplanar treatment beams with high precision under continual X-ray image guidance

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Treatment planning begins with obtaining one or more three-dimensional (3D) images that allows the target volume and nearby organs at risk (OARs) to be visualized. Once acquired the 3D images are transferred to the MultiPlan® Treatment Planning System (TPS) via a dedicated database server.

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The number of nodes in the different path sets ranges from 23 to 133.

Direction points are determined automatically based on the beam generation mode, which is either isocentric or non-isocentric. The isocentric mode allows the user to position one or more pseudo-isocenters within the patient model resulting in one candidate beam from each node to each pseudo-isocenter. The non-isocentric mode takes advantage of the ability of the robotic manipulator to direct each beam at a unique point within the patient, without any need to reposition the patient between beams, by generating a large number of direction points (typically 1,000–6,000) semi-randomly within the target volume and distributes these uniformly among the nodes to form the candidate beam set. The user can choose to prevent candidate beams from passing through OARs, which can be a method to minimize the dose delivered to small radiosensitive structures such as the lens of the eye or the thyroid gland.

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The user then selects between one and three fixed collimator sizes, or between one and twelve Iris Collimator field sizes, which are assigned to subsets of the candidate beam set.

Sounds interesting and promising. Just to clarify, does this allow a surgical procedure without an actual incision by focusing the energy (um, or whatever it is) past the skin and toward a specific point, or is it more that it allows for a finer or more delicate touch to perform surgery with better precision through a smaller incision?

As for CN VIII, like all except one cranial nerve, it originates on the brain, and in this case, the brainstem. So for a short distance, it is surrounded by all three layers of the meninges. This one pretty quickly reaches its hole in the skull (when Mom told you she needed something like another hole in the head, she wasn't kidding! We have a LOT of holes in the head where cranial nerves travel), so has a fairly short "intradural" course before traveling through its own tunnel to the ear. That nerve carries information for both hearing and balance/equilibrium, so I'm sure your friend is more concerned about dizziness caused by the tumor compressing the nerve than hearing loss in one ear! I hope his procedure goes well!

Just to clarify, does this allow a surgical procedure without an actual incision by focusing the energy (um, or whatever it is) past the skin and toward a specific point, or is it more that it allows for a finer or more delicate touch to perform surgery with better precision through a smaller incision?

Mounted on the Robot is a compact X-band linac that produces 6MV X-ray radiation. The linac is capable of delivering approximately 600 cGy of radiation each minute - a new 800 cGy / minute model was announced at ASTRO[6][7] 2007. The radiation is collimated using fixed tungsten collimators (also referred to as “cones”) which produce circular radiation fields. At present the radiation field sizes are: 5, 7.5, 10, 12.5, 15, 20, 25, 30, 35, 40, 50 and 60 mm. ASTRO 2007 also saw the launch of the IRIS[7] variable-aperture collimator which uses two offset banks of six prismatic tungsten segments to form a blurred regular dodecagon field of variable size which eliminates the need for changing the fixed collimators.

I had a family member go for this treatment just last week, I never knew much about the procedure actually, but it was talked about alot.

mcknia,

I wish your loved one the best.

Rhody...