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Biomedical subjects

J Daniel Bourland

Publications and source records attributed to J Daniel Bourland.

5 recordsLinked to original sources
PubMed2003

Gentlemen (and ladies), choose your weapons: Gamma knife vs. linear accelerator radiosurgery.

This article compares and contrasts Gamma Knife radiosurgery with linear accelerator-based radiosurgery; where appropriate, Cyberknife technology is discussed. Topics covered are: positioning of the head (invasive versus non-invasive positioning systems); collimator construction; beam properties; beam arrangements; treatment planning; and issues regarding manpower (including a discussion of patient repositioning during treatment), machine availability, and financial considerations.

Brain Neoplasms↗
PubMed2003

The evolving role of biological imaging in stereotactic radiosurgery.

Stereotactic radiosurgery is used for highly focused radiation treatment of relatively small intracranial targets. Extracranial treatment systems are currently in development and used at a few centers. Approaches are image-based or image-guided, using CT and/or MR anatomical imaging. Biological imaging may provide non-invasive detection of the biological character and spatial extent of intracranial and extracranial targets. Potential uses of biological imaging in stereotactic radiosurgery include target delineation and normal tissue identification. These aspects are reviewed to explore the potential uses and impact these images may have on radiosurgery treatment.

Brain Neoplasms↗
PubMed2002

Spectral reconstruction of high energy photon beams for kernel based dose calculations.

A kernel-based dose computation method with finite-size pencil beams (FSPBs) requires knowledge of the photon spectrum. Published methods of indirect spectral measurements using transmission measurements through beam attenuators use mathematical fits with a large number of parameters and constraints. In this study, we examine a simple strategy for fitting transmission data that models important physical characteristics of photon beams produced in clinical linear accelerators. The shape of an unattenuated bremsstrahlung spectrum is known, varying linearly from a maximum at zero energy to a value of zero at a maximum energy. This unattenuated spectrum is altered primarily by absorption of low energy photons by the flattening filter, causing the true spectrum to roll off to zero at low photon energies. A fitting equation models this behavior and has these advantages over previous methods: (1) the equation describes the shape of a bremsstrahlung spectrum based on physical expectations; and (2) only three fit parameters are required with a single constraint. Results for 4 MV and 6 MV accelerators for central axis and off-axis beams show good agreement with the maximum, average and modal energies for known spectra. Previously published models, representations of beam fluence (energy fluence, dN/dE), experimental methods, and the fitting process are discussed.

Algorithms↗