Photon beam dosimetry at a blocked beam edge using diffusion approximation.

I J Das; K R Kase; J E Kelley; B L Werner

doi:10.1088/0031-9155/37/4/008

Home/Archive/PubMed

PubMed · 11419479

Photon beam dosimetry at a blocked beam edge using diffusion approximation.

I J Das·K R Kase·J E Kelley·B L Werner

View original source ↗Export metadata ↓

Abstract

A simple analytical model is presented for the transport of secondary electrons at a photon beam edge using the energy averaged solution of the Boltzmann equation, originally developed for beta-ray dosimetry at a plane interface. Dose at a point under a block is assumed to be due to secondary electrons and the scattered photons generated from the primary photon beam. The diffusion approximation is used for the secondary electron transport at a virtual plane interface created by the block. The dose from the scattered photon component is treated as decaying exponentially with distance from the beam edge. Comparisons made with the model and measurements are in general agreement for high energy accelerator beams.

Explore related subjects

Diffusion Mathematics Models, Theoretical Phantoms, Imaging Photons Radiation Dosage Radiometry Scattering, Radiation Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

I J Das, K R Kase, J E Kelley, B L Werner. 1992. Photon beam dosimetry at a blocked beam edge using diffusion approximation.. https://doi.org/10.1088/0031-9155%2F37%2F4%2F008

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

A-B-A-B-A block amphiphiles. Balance between hydrophilic and hydrophobic segmentation.

Explore the source record for details and available documents.

Diffusion↗

PubMed2007

Effect of surface treatment on diffusion and domain formation in supported lipid bilayers.

Supported lipid bilayers are widely used as model systems due to their robustness. Due to the solid support, the properties of supported lipid bilayers are different from those of freestanding bilayers. In this article, we examine whether different surface treatments affect the properties of supported lipid bilayers. It will be shown that depending on the treatment method, the diffusion of the lipids can be adjusted approximately threefold without altering the composition. Additionally, as the bilayer-support interaction decreases, it becomes easier to form coexisting liquid-ordered and liquid-disordered domains. The physical/chemical alterations that result from the different treatment methods will be discussed.

Diffusion↗

PubMed2007

An early example of evidence-based medicine: hypoxemia due to nitrous oxide.

Diffusion anoxia. By Bernard Raymond Fink. Anesthesiology 1955; 16:511-14. In 1955, Dr. Bernard Raymond Fink published his findings that described the mechanism by which hypoxemia occurred when nitrous oxide-oxygen anesthesia was discontinued and room air breathing commenced. Using an ear oximeter and brachial artery blood gases, he measured oxygen saturation in eight healthy patients who had received 75% nitrous oxide-25% oxygen for gynecologic surgery. He showed that oxygen saturation decreased from 5% to 10% and often reached a value below 90% when the patient began room air breathing after the nitrous oxide-oxygen was discontinued. The effect was seen over a 10-min period. He concluded that "anoxia arises because the outward diffusion of nitrous oxide lowers the alveolar partial pressure of oxygen." This phenomenon can become a causative factor of cardiac arrest in patients with impaired pulmonary or cardiac reserves.

Diffusion↗