Showing papers by "Varian Associates published in 2000"

Breathing-synchronized radiotherapy program at the University of California Davis Cancer Center.

Abstract: In this paper we present a complete description of the breathing synchronized radiotherapy (BSRT) system, which has been jointly developed between the University of California Davis Cancer Center and Varian Associates. BSRT is a description of an emerging radiation oncology procedure, where simulation, CT scan,treatment planning, and radiation treatment are synchronized with voluntary breath-hold, forced breath-hold, or breathing gating. The BSRT system consists of a breathing monitoring system (BMOS) and a linear accelerator gating hardware and software package. Two methods, a video camera-based method and the use of wraparound inductive plethysmography (RespiTrace), generate the BMOS signals. The BMOS signals and the synchronized fluoroscopic images are simultaneously recorded in the simulation room and are later analyzed to define the ideal treatment point (ITP) where organ motion is stationary. The BMOS signals at ITP can be used to gate a CT scanner or a linear accelerator to maintain the same organ configuration as in the simulation. The BSRT system allows breath-hold or gating. This dual role allows the system to be applicable for a variety of patients, i.e., the breath-hold method for those patients who can maintain and reproduce the ITP, and the forced breath-hold or gating method for those who are not ideal for voluntary breath-hold.

Method and apparatus creating a radioactive layer on a receiving substrate for in vivo implantation

Abstract: An apparatus and method of forming a radioactive stent having a radioactive layer. A solution containing a radioactive isotope depositing substance in solution is provided and placed into contact with the stent or any other substrate material capable of receiving the radioactive isotope. The radioactive isotope is deposited on the stent or substrate material. Preferably a phosphorous isotope is used and the solution is polymerized forming polymer chains containing the radioactive isotope. In this embodiment, the phosphorous is bonded with the substrate material in a phosphorous-oxygen-phosphorous network.

IR fiber optics development at the Naval Research Laboratory

Abstract: We report the first technology demonstration of the use of an IR fiber cable in an IRCM system for missile jamming. The IR fiber cable contains sulphide glass fibers which possess low loss, high strength and high threshold to laser damage. The fiber cable was used to transmit the output from a laser operating in the 2 - 5 micrometers atmospheric window to a Jam Head located remote from the laser. The demonstration was successful and fiber cable performed remarkably well and without damage.

Phase reconstruction from difference equations: a branch point tolerant method

Abstract: Numerous optical engineering applications lead to two two- dimensional difference equations for the phase of a complex field. We will demonstrate that, in general, the solution for the phase can be decomposed into a regular, single-valued function determined by the divergence of the phase gradient, as well as a multi-valued function determined by the circulation of the phase gradient; this second function has been called the 'hidden phase.' The standard least-squares solution to the two-dimensional difference equations will always miss this hidden phase. We will present a solution method that gives both the regular and hidden parts of the phase. Finally, we will demonstrate the method with several examples from both speckle imaging and shearing interferometry.