Gamma Knife surgery in the management of radioresistant brain metastases in high-risk patients with melanoma, renal cell carcinoma, and sarcoma.

Object: The purpose of this study was to examine the results of using Gamma Knife surgery (GKS) for brain metastases from classically radioresistant malignancies.

Methods: The authors retrospectively reviewed the records of 76 patients with melanoma (50 patients), renal cell carcinoma (RCC; 23 patients), or sarcoma (3 patients) who underwent GKS between August 1998 and July 2007. Overall patient survival, intracranial progression, and local progression of individual lesions were analyzed.

A dwell position verification method for high dose rate brachytherapy.

Misplacement of dwell positions is a potential source of misadministration in high dose rate brachytherapy. In this work we present a dwell position verification method using fluoroscopic images. A mobile C-arm fluoroscopic machine is used to take a snapshot of the treatment machine's check cable as it reaches the most distal dwell position.

Gamma knife surgery for trigeminal neuralgia: improved initial response with two isocenters and increasing dose.

Object: The authors sought to evaluate the initial response of trigeminal neuralgia (TN) to gamma knife surgery (GKS) based on the number of shots delivered and radiation dose.

Methods: Between September 1998 and September 2003, some 63 patients with TN refractory to medical or surgical management underwent GKS at Upstate Medical University. Ten patients had multiple sclerosis and 25 patients had undergone prior invasive treatment.

Determination of 137Cs dosimetry parameters according to the AAPM TG-43 formalism.

Traditional treatment planning systems calculate dose distributions around 137Cs intracavitary sources by interpolating stored dose rate tables or by Sievert-type integrals. Some of the recently introduced planning systems, such as the Varian BrachyVision and Eclipse (Varian Medical Systems, Palo Alto, CA), have discontinued the use of tables and have implemented instead the AAPM TG-43 formalism as a brachytherapy dosimetry calculation algorithm. In this work we present the dosimetry parameters for 137Cs intracavitary sources as determined according to the TG-43 formalism.

Evaluation of two water-equivalent phantom materials for output calibration of photon and electron beams.

Two commercially available water-equivalent solid phantom materials were evaluated for output calibration in both photon (6-15 MV) and electron (6-20 MeV) beams. The solid water 457 and virtual water materials have the same chemical composition but differ in manufacturing process and density. A Farmer-type ionization chamber was used for measuring the output of the photon beams at 5- and 10-cm depth and electron beams at maximum buildup depth in the solid phantoms and in natural water.

The linear-quadratic model and fractionated stereotactic radiotherapy.

Purpose: To determine the dose per fraction that could be used when gamma knife or linear accelerator-based stereotactic treatments are delivered in 2 or more fractions.

Methods And Materials: The linear-quadratic (LQ) model was used to calculate the dose per fraction for a multiple-fraction regimen which is biologically equivalent to a given single-fraction treatment. The results are summarized in lookup tables.

On the use of C-arm fluoroscopy for treatment planning in high dose rate brachytherapy.

Treatment planning for brachytherapy requires the acquisition of geometrical information of the implant applicator and the patient anatomy. This is typically done using a simulator or a computed tomography scanner. In this study, we present a different method by which orthogonal images from a C-arm fluoroscopic machine is used for high dose rate brachytherapy treatment planning.