Technical Note: Empirical altitude correction factors for well chamber measurements of permanent prostate and breast seed implant sources.

Purpose: Previous studies in the literature have measured an altitude effect for low-energy brachytherapy seeds; a correction factor applied in addition to P to account for the breakdown of Bragg-Gray cavity theory at low energies in well-type ionization chambers. In clinical practice, many centers use altitude correction factors that are not seed-model-specific. The purpose of this work is to present altitude correction factors for several seed models without documented factors in the literature.

The effect of contouring variability on dosimetric parameters for brain metastases treated with stereotactic radiosurgery.

Purpose: To quantify the effect of contouring variation on stereotactic radiosurgery plan quality metrics for brain metastases.

Methods And Materials: Fourteen metastases, each contoured by 8 physicians, formed the basis of this study. A template-based dynamic conformal 5-arc dose distribution was developed for each of the 112 contours, and each dose distribution was applied to the 7 other contours in each patient set.

Image-Guided Treatment of Fractionated Stereotactic Radiotherapy Patients: A Quantitative Analysis of Pre- and Post-Treatment Orthogonal kV Images of Patients Immobilized with Thermoplastic Masks.

Objectives: To measure setup and intrafraction variability for intracranial targets during treatment of patients immobilized with a Brainlab, Inc. thermoplastic head mask using ExacTrac© imaging on the treatment unit.

Patients And Methods: Between November 2007 and June 2008, 12 patients were treated with cranial fractionated stereotactic radiation therapy for 25-28 fractions.

Evaluation of stereotactic radiosurgery conformity indices for 170 target volumes in patients with brain metastases.

A database of clinically approved stereotactic radiosurgery treatment plans was created. One hundred and seventy targets in the database were then retrospectively evaluated using conformity indices suggested by RTOG, SALT-Lomax and Paddick. Relationships between the three alternative conformity indices were determined.

Functional CT in lung with a conventional scanner: simulations and sampling considerations.

Due to rapid transit times, motion artefacts from breathing and the low signal intensity, functional computed tomography (f-CT) studies in lung tissue remain challenging with conventional CT scanners. The purpose of this study is to examine the accuracy of parameter estimates when performing deconvolution analysis with signals from lung tissue. The effects of partial volume averaging in lung tissue, differing transit times, variable vascular and capillary responses, expected noise levels, differing sampling rate and durations were simulated on a computer.