Indications for Single Fraction or Multi-Session Radiosurgery
Advantages of Single Session Radiosurgery
Advantages of Multi-Session Radiosurgery
Determination of Number of Sessions
Multi-Session_Radiosurgery_Procedure 

Indications for Single Fraction or Multi-Session Radiosurgery

The CyberKnife® can be used for single session and multi-session radiosurgery. When used for single session treatment it offers a non-invasive highly accurate alternative to frame-based systems, but also allows for delivery of multiple sessions when tumor size, tumor location, or presence of critical normal structures makes multi-session treatment desirable. When used for single fraction treatment, it offers accuracy at least as good as any other system (0.5 mm for static targets).

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Advantages of Single Session Radiosurgery

When used for single session radiosurgery, CyberKnife is completely non-invasive and offers comfort and convenience not available with other systems. Treatment efficacy for tumors throughout the body is documented in a large body of medical literature, with over 60,000 thousand patients treated thus far. 

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Advantages of Multi-Session Radiosurgery

Multi-session radiosurgery is sometimes used for large tumors, tumors in critical locations, or tumors adjacent to critical normal structures where the dose to the critical normal structure is of concern. Multi-session treatment is based on biologic principles that damage to normal structures is likely less with fractionated treatment in some circumstances.

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Determination of Number of Sessions

The number of sessions that a physician might recommend is based on a variety of circumstances but especially tumor size and location. Generally it is not the tumor itself, (i.e. pathologic diagnosis) but rather its proximity to critical structures such as the hearing (cochlear) or vision (optic) nerve that determines the number of stages.

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Multi-Session Radiosurgery Procedure

The process for multi-session radiosurgery on the CyberKnife is very similar to a single session treatment. The patient is placed on the treatment table and treated with radiosurgery. However, in the case of multi-session radiosurgery, only a portion of the total dose is administered during a given treatment. The remaining dose is delivered in identical fashion on subsequent days. Some centers opt to treat on successive days, while others may allow a day or two to pass between treatments. The optimal timing has not yet been determined.

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