Associating dose-volume characteristics with theoretical radiobiological metrics for rapid Gamma Knife stereotactic radiosurgery plan evaluation.

Purpose: To examine general dose-volume characteristics in Gamma Knife (GK) plans which may be associated with higher tumor control probability (TCP) and equivalent uniform dose (EUD) using characteristic curve sets.

Methods: Two sets of dose-volume histograms (DVHs) were exported alongside an analytical purpose-generated DVH: (a) single-shot large collimator (8 or 16 mm) emulated with multiple shots of 4 mm collimator. (b) shot-within-shot (SWS) technique with isodose lines (IDLs) of 40-75%.

The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery.

OBJECTIVE Functional Gamma Knife radiosurgery (GKRS) procedures have been increasingly used for treating patients with tremor, trigeminal neuralgia (TN), and refractory obsessive-compulsive disorder. Although its rates of toxicity are low, GKRS has been associated with some, if low, risks for serious sequelae, including hemiparesis and even death. Anecdotal reports have suggested that even with a standardized prescription dose, rates of functional GKRS toxicity increase after replacement of an old cobalt-60 source with a new source.

A technique to re-establish dose distributions for previously treated brain cancer patients in external beam radiotherapy.

Tumor recurrences or new tumors may develop after irradiation of local lesion(s) in the brain, and additional radiotherapy treatments are often needed for previously treated patients. It is critical to re-establish the dose distributions delivered during the previous treatment in the current patient geometry, so that the previous dose distributions can be accurately taken into consideration in the design of the current treatment plan. The difficulty in re-establishing the previous treatment dose distributions in the current patient geometry arises from the fact that the patient position at the time of reirradiation is different from that at the previous treatment session.

Comparison of an image registration technique based on normalized mutual information with a standard method utilizing implanted markers in the staged radiosurgical treatment of large arteriovenous malformations.

Purpose: To compare a noninvasive technique based on normalized mutual information for registering image sets associated with staged radiosurgical treatments of large arteriovenous malformations (AVMs), with a gold-standard method using radiographically evident markers implanted in the skull.

Methods: Nine patients receiving multistage treatment of large AVMs at the University of California at San Francisco (UCSF) gamma knife facility were included in this study. For each patient, the transformations of shot coordinates between a reference treatment stage and subsequent treatment stages were determined at UCSF, based on radiographically defined coordinates of implanted markers in each stereotactic space.