Early expansion of the intracranial CSF volume after palliative whole-brain radiotherapy: results of a longitudinal CT segmentation analysis.

Purpose: To assess cerebral atrophy after radiotherapy, we measured intracranial cerebrospinal fluid volume (ICSFV) over time after whole-brain radiotherapy (WBRT) and compared it with published normal-population data.

Methods And Materials: We identified 9 patients receiving a single course of WBRT (30 Gy in 10 fractions over 2 weeks) for ipsilateral brain metastases with at least 3 years of computed tomography follow-up. Segmentation analysis was confined to the tumor-free hemi-cranium.

Poster - Thurs Eve-21: Experience with the Velocity(TM) pre-commissioning services.

As the first Canadian users of the Velocity™ program offered by Siemens, we would like to share our experience with the program. The Velocity program involves the measurement of the commissioning data by an independent Physics consulting company at the factory test cell. The data collected was used to model the treatment beams in our planning system in parallel with the linac delivery and installation.

Liquid embolisation material reduces the delivered radiation dose: a physical experiment.

Objective: To test a new hypothesis that the glue/contrast admixture used for embolisation reduces the dose delivered to AVMs using an experimental model.

Method: A model was created using a block of "solid water" (6 x 5 x 2 cm) with twelve wells of different depths. Different concentrations of the glue admixture (Enbucrilate + Lipiodol) were used.

Fractionated (split dose) radiosurgery in patients with recurrent brain metastases: implications for survival.

Radiosurgery is conventionally prescribed for brain metastases with a single dose of radiation. Fractionation has been advocated to improve tumour control. A multivariate analysis of prognostic factors including fractionation has been performed in two consecutive prospective radiosurgery protocols with and without fractionation in order to identify an association, if any, between fractionation and survival.

Embolization before radiosurgery reduces the obliteration rate of arteriovenous malformations.

Objective: To evaluate the arteriovenous malformation (AVM) obliteration rate and the clinical outcome after radiosurgery in patients with and without previous embolization.

Methods: Of 244 patients who underwent linear accelerator radiosurgery for AVMs at the Sunnybrook Health Sciences Centre between 1989 and 2000, 61 patients had embolization before radiosurgery and complete follow-up for at least 3 years. For 47 of these 61 patients (Group A, embolization plus radiosurgery), we were able to find 47 matching patients without previous embolization (Group B, radiosurgery alone).

Radiosurgical treatment for rolandic arteriovenous malformations.

Object: The authors reviewed the radiosurgical outcomes in patients with arteriovenous malformations (AVMs) located in the rolandic area, including the primary motor and sensory gyri.

Methods: The study population consisted of 38 patients with rolandic-area AVMs who underwent linear accelerator radiosurgery at the University of Toronto between 1989 and 2000. Obliteration rate, risk of hemorrhage during the latency period, radiation-induced complications, seizure control, and functional status were evaluated.

Pediatric arteriovenous malformation: University of Toronto experience using stereotactic radiosurgery.

Introduction And Background: Arteriovenous malformations (AVMs) are congenital vascular lesions of the brain, which behave differently in pediatric population compared to adults. Treatment of pediatric AVMs includes a combination of microsurgery, embolization and radiation therapies. However, the role of radiosurgery in the treatment of pediatric AVMs is not fully accepted because of concerns regarding the long-term effects of radiation on the pediatric brain.

Radiosurgical retreatment for brain arteriovenous malformation.

Objective: To analyze our experience with a second radiosurgical treatment for brain arteriovenous malformations (BAVMs) after an unsuccessful first radiosurgical treatment.

Methods: Between 1993 and 2000, 242 patients were treated by the Toronto Sunnybrook Regional Cancer Center using a LINAC system. Fifteen of these patients required a second radiosurgical intervention due to the failure of the first procedure.

Testing the radiosurgery-based arteriovenous malformation score and the modified Spetzler-Martin grading system to predict radiosurgical outcome.

Object: The aim of this study was to validate the radiosurgery-based arteriovenous malformation (AVM) score and the modified Spetzler-Martin grading system to predict radiosurgical outcome.

Methods: One hundred thirty-six patients with brain AVMs were randomly selected. These patients had undergone a linear accelerator radiosurgical procedure at a single center between 1989 and 2000.

Radiosurgery for basal ganglia, internal capsule, and thalamus arteriovenous malformation: clinical outcome.

Objective: Radiosurgery is accepted as the first option for treating deep arteriovenous malformations (AVMs), although the clinical outcome in this subgroup of brain AVMs is not well studied. The objective of this study is to review our experience with radiosurgical treatment for these AVMs.

Methods: Between October 1989 and December 2000, 45 patients with deep AVMs (including basal ganglia, internal capsule, and thalamus) underwent stereotactic radiosurgery.

The regional Monte Carlo method: a dose calculation method based on accuracy requirement.

In this work we propose the regional Monte Carlo (RMC) method of dose calculation. This method combines the Monte Carlo (MC) algorithm and a non-MC algorithm (such as the convolution method) for optimal speed and accuracy in dose calculation for both photon and electron beams and for various irradiation and patient geometries. For specific regions in the geometry where high accuracy is required but difficult to obtain with analytical or empirical calculations, such as critical organs surrounded by complicated inhomogeneities, the MC algorithm is used.

Monte Carlo based phase-space evolution for electron dose calculation.

A system of computer codes based on phase-space evolution is developed and applied to low energy therapeutic electron beams. Monte Carlo (EGS4) is used to pre-calculate the electron transport and dose deposition in a 0.5 cm width cubic voxel.