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Poster - Thurs Eve-18: Performance evaluation of MV CT imaging on the HI ART II tomotherapy unit

Medical physics 2008年第7PART2期35卷 3404页

作者： B Disher S Gaede J J Battista Department of Medical Biophysics University of Western Ontario London ON. Physics & Engineering Department London Regional Cancer Program London ON.

The HI-ART II unit (TomoTherapy Inc., Madison WI) is a modality used by the London Regional Cancer program (LRCP) for radiation therapy. This machine uses the same source of Megavoltage energy radiation to image (3.5 MV) and to treat (6MV) patients, combining the functionality of a traditional linear accelerator and CT simulator into one unit. Thus, it is possible to assess patient positioning and adjust for anatomy changes just prior to radiation therapy. Unfortunately, at MV energy levels, the physics of radiation interaction limits image quality, and gives rise to an inherent dose limitation concern that enhances noise levels. Therefore, we propose to quantify the image quality produced by the HI-ART II unit using techniques established for kVCT scanner technology. Our study involved the use of three standard phantoms to test image resolution, noise, uniformity, and linearity for a 512 × 512 reconstruction matrix and three scan pitch settings (0.8, 1.6, and 2.4). Results follow: linearity between MV CT number versus relative electron density was observed, noise calculations ranged from 2.15-2.51%, and a distinct central artifact was revealed during uniformity testing. The linearity between MV CT number versus relative electron density implies that MV CT images are highly suitable for dose calculations. MV CT image quality of uniform phantoms were acceptable and demonstrated noise levels higher than those produced by kVCT simulators. Further study is necessary to correct for the central artifact in MV CT images.

关键词： Cancer Computed tomography Dosimetry Medical image noise Medical image quality Medical image reconstruction Medical imaging Radiation therapy Radiation treatment Therapeutics

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Poster - Thurs Eve-41: Imaging and radiation delivery in helical tomotherapy: Phantom study of a moving target

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Medical physics 2008年第7PART3期35卷 3409页

作者： C Gallagher S Yartsev J Van Dyk Department of Physics and Engineering London Regional Cancer Program London Health Sciences Centre and Department of Medical Biophysics University of Western Ontario London ON.

Treating lung cancer with radiation therapy by guaranteed delivery of the prescription dose to the target is difficult due to tumour motion. The standard approach to account for motion effects consists of adding a substantial margin to a lesion visible on the CT study. Larger irradiated volume results in increased dose deposition in healthy lung and the potential for patient complications. This investigation focuses on determining the optimal choice of planning CT mode for improved radiation delivery in terms of better target coverage and sparing of healthy organs. Dosimetric measurements were performed on a helical tomotherapy unit. A Quasar® (Modus Medical Devices, London, ON) respiratory phantom was imaged while a polystyrene target moved sinusoidally with a period of 4 s and amplitude of 2 cm. For target moving in superior-inferior and lateral directions, conventional fast-CT image studies were created, as well as maximum intensity projection (MIP) and average intensity projection (AveIP) image studies using four-dimensional CT information. All types of CT studies were used to develop treatment plans with a prescription of 2 Gy per fraction to the target outlined according to the imaged data. Measurements of dose deposition were made in four locations within the moving target using an Exradin A1SL ion chamber. Comparing all results to the dose measured at the centre of the static phantom, the MIP plans overdose the target, the fast-CT results vary from case to case, while the AveIP plans provide consistent dose distribution across the target within 2% of the normalization dose.

关键词： Anatomy Cancer Computed tomography Dosimetry Drug delivery Lungs Medical imaging Radiation therapy Radiation therapy equipment Radiation treatment

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Nanotech innovations: Nanotechnology enterprise at Michigan technological university

Nanotech innovations: Nanotechnology enterprise at Michigan ...

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2008 AIChE Annual Meeting, AIChE 100

作者： Jaszczak, John A. Raber, Mary Bennett, Michael Alaraje, Nasser Bergstrom, Paul L. Department of Physics Michigan Technological University 1400 Townsend Dr. Houghton MI 49931 United States Enterprise Program Michigan Technological University 1400 Townsend Dr. Houghton MI 49931 United States Department of Social Sciences Michigan Technological University 1400 Townsend Dr. Houghton MI 49931 United States School of Technology Michigan Technological University 1400 Townsend Dr. Houghton MI 49931 United States Department of Electrical and Computer Engineering Michigan Technological University 1400 Townsend Dr. Houghton MI 49931 United States Science Technology and Society Vassar College Poughkeepsie NY 12604-0246 United States

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Sci-Fri PM: Planning-03: Fundamental understanding of the inter-relation of arc range, angular dose rate and MLC leaf position optimization of Intensity Modulated Arc Therapy for a concave target

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Medical physics 2008年第7PART3期35卷 3412页

作者： M Oliver J Chen E Wong Dept of Medical Biophysics University of Western Ontario. Dept of Physics and Engineering London Regional Cancer Program London Health Sciences Center London ON. Dept of Physics and Astronomy University of Western Ontario.

Intensity Modulated Arc Therapy (IMAT) is a rotational variant of Intensity Modulated Radiation Therapy (IMRT) that can be implemented with or without angular dose rate optimization. The purpose of this study is to determine the inter-relationship among arc range, Multi-Leaf Collimator (MLC) leaf positions and angular dose rate optimizations for IMAT delivery of a concave target. A concave planning target volume (PTV) with central cylindrical organ at risk (OAR) was used in dissecting the inter-relationships. Plans with full and limited arc range were generated using leaf position optimization (LPO) alone, angular dose rate optimization (ADRO) alone or LPO followed by ADRO. Two initial IMAT arcs were conformal avoidance arcs created with 5° angular increments where MLC leaf positions were determined from the beams eye view to irradiate the PTV but avoid the OAR. The objective function value (evaluating dose to PTV and OAR), a conformity index, dose homogeneity index, mean dose to OAR and normal tissues were computed and used to evaluate the treatment plans. Dose rate variations and MLC leaf movements as a function of gantry angle were examined in this approach. The results demonstrate that LPO followed by ADRO provided the lowest objective function values, best conformity and dose homogeneity indices, and third in mean dose to OAR and normal tissues for the complete arc range. Future work will address different strategies for simultaneously optimizing both the MLC leaf positions and the variable angular dose rate for IMAT delivery and compare single and multiple arc plans.

关键词： Anatomy Collimators Dosimetry Intensity modulated radiation therapy Multileaf collimators

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Review of designing an information processing ware for a Diabetic Chip

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Journal of Diabetes Science and Technology 2008年第5期2卷 873-881页

作者： Al-Sheikh, Youssef T. Andrade, Joseph D. Millington, Jared Wong, Anthony Department of Biomedical Informatics School of Medicine University of Utah Salt Lake City UT 84112 26 South 2000 East United States Department of Bioengineering School of Engineering University of Utah Salt Lake City UT United States Department of Physics School of Science University of Utah Salt Lake City UT United States Intermountain Healthcare Salt Lake City UT United States Department of Ophthalmology and Visual Science School of Medicine University of Utah Salt Lake City UT United States Program in Human Molecular Biology and Genetics Eccles Institute of Human Genetics University of Utah Salt Lake City UT United States Utah Science Center at The Leonardo Salt Lake City Main Library Salt Lake City UT United States

Miniaturization of clinical chemistry analyzers can empower research conducted to better understand, diagnose, manage, and cure diseases such as diabetes. For the last decade, we have been working on the design and development of miniaturized clinical chemistry devices, including a Diabetic Chip (diabetiChip). These devices measure a small array of analytes, are small, portable, fast, easy-to-operate, and inexpensive. The chosen analytical method for the diabetiChip uses bioluminescence, which is highly sensitive and specific, and is based on photon counting and specific enzymatic reactions. Bioluminescent reactions were intentionally chosen for analyzing metabolic reactions because they use some of the central nodes of metabolism, such as adenosine triphosphate. Operations of the diabetiChip's information processing ware are the focus of this paper;we show the feasibility of using a set of kinase-containing enzymatic reactions of a firefly bioluminescencecoupled glucose assay in designing the diabetiChip. We have developed and tested the feasibility of the glucose assay;the assay's analytical detection limits (before sample dilution) were 5-185 μM. Uncertainty associated with reporting a 100 μM concentration was about ± 5 μM. The results show that an FFL bioluminescentcoupled glucose assay is promising in terms of reducing sample volume and cost. The concept of GlucoFaces^™ in visualizing measurements of the diabetiChip is also discussed. © Diabetes Technology Society.

关键词： Assay calibration Bioluminescence Diabetic Chip Information ware Lab-on-a-chip Simulation Visual display

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High temperature corrosion of materials in supercritical water and liquid lead-alloy environments

High temperature corrosion of materials in supercritical wat...

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Interfacial Electrochemistry and Chemistry in High Temperature Media - 212th ECS Meeting

作者： Sridharan, K. Chen, Y. Tan, L. Machut, M. Kruizenga, A. Ren, X. Allen, T.R. Department of Engineering Physics University of Wisconsin Madison United States Materials Science Program University of Wisconsin Madison United States

ISBN: (纸本)9781605603124

The Supercritical Water-cooled Reactor (SCWR) and Lead-cooled Fast Reactor (LFR) are among the six reactor concepts identified by the Generation IV initiative for the next generation nuclear reactors. Materials degradation due to corrosion is a significant issue in both supercritical water and molten lead (-alloy) environments, particularly at the intended higher temperatures of application. In supercritical water, corrosion of ferritic and austenitic steels and Inconel alloys occurs mainly by the growth of an oxide layer on the surface. In molten lead (-alloy), corrosion can occur by dissolution of the material, oxidation, or by the penetration of liquid metal into the material primarily along the grain boundaries. Surface treatment of ferritic steels by the incorporation of thin film of oxidation-resistant materials has been shown to mitigate corrosion in these aggressive environments. Grain boundary engineering (GBE) reduces spallation of oxide layers in austenitic steels in supercritical water environment. © The Electrochemical Society.

关键词： Ferrite

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The evolution of the edge program in its fourth year

The evolution of the edge program in its fourth year

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114th Annual ASEE Conference and Exposition, 2007

作者： Dimitriu, Dan O'Connor, Jerry San Antonio College United States Two-Year College Division of ASEE Engineering Program San Antonio College United States Department Chairperson for Physics Engineering and Architecture AAPT Committee on Physics Two Year Colleges

No abstract available

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The need for a quality control system for community college engineering education

The need for a quality control system for community college ...

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114th Annual ASEE Conference and Exposition, 2007

作者： Dimitriu, Dan O'Connor, Jerry San Antonio College United States Two-Year College Division of ASEE Engineering Program San Antonio College United States Texas Alliance for Minority Participation Program United States Department Chairperson for Physics Engineering and Architecture

This paper is based on a collaborative effort between the National Academy of engineering and the National Research Council, with support from the National Science Foundation that was initiated to improve engineering education at community colleges and improve the prospects for community college students' achievement of Bachelors Degrees in engineering at four-year institutions. The paper attempts to establish some basic ground rules for building a quality control assessment system and creating active partnerships between Community Colleges and the four-year Universities with an ongoing dialog. This effort is also directed at building a unified approach for attracting and retaining students in engineering and to articulate a seamless engineering curriculum for a continuum of education that will fortify engineering education for the new millennium. © American Society for engineering Education, 2007.

关键词： engineering education

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Boron coating to combat corrosion and oxidation

Boron coating to combat corrosion and oxidation

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作者： Petrova, Roumiana S. Suwattananont, Naruemon Pallegar, Kranthi K. Vangaveti, Raghasudha Materials Science and Engineering Program Physics Department New Jersey Institute of Technology University Heights Newark NJ 07102 United States

The present study describes the recent investigation of boronized surface coating on Steel, Ni super alloy and pure Tantalum. The coatings were produced by thermo-chemical treatment with an original technology powder mixture at the temperature range of 850-1050°C. Metallographic examination, X-ray diffraction (XRD) and microhardness testing were used to determine the characteristics of the diffusion layer compared with the substrate. The continuous weighting method and the potentiodynamic polarization measurements were used to investigate the corrosion resistance of the specimen surface before and after boronizing. Also, the high temperature oxidation method detected by differential thermal analysis (TGA) was used to observe the oxidation resistance of unboronized and boronized specimens. It was shown that the boronizing process created a boride layer with a thickness of 10-80 μm depending on substrates, temperatures, and times, with microhardness of about 8-10 times greater than that of the substrate. The corrosion resistance of the boronized coating was determined to be 6-10 times higher than that of the substrate. As well, the oxidation resistance of the boronized coating was 3-5 times better than that of the substrate.

关键词： Protective coatings

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Anisotropic fluorocarbon plasma etching of Si/SiGe heterostruetures

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Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures 2007年第2期25卷 404-409页

作者： Ding, R. Klein, L.J. Eriksson, M.A. Wendt, A.E. Materials Science Program University of Wisconsin-Madison Madison WI 53706 Department of Physics University of Wisconsin-Madison Madison WI 53706 Department of Electrical and Computer Engineering University of Wisconsin-Madison Madison WI 53706

Fluorocarbon plasma etching of Si/SiGe heterostructures is demonstrated as a method for fabrication of quantum devices with vertical sidewalls. The heterostructures consist of layers of Si and SiGe, and anisotropic etching of the heterostructures using plasmas to isolate device elements is an attractive approach to fabricating devices. A challenge that has limited the use of fluorocarbon etching is the difference in Si and SiGe etch rates under comparative conditions. Preferential etching of SiGe can lead to undercutting beneath the top Si layer, causing a reduction in critical device dimensions of unknown magnitude. By using fluorocarbon etch gases with high carbon content, fluorocarbon sidewall passivation improves the anisotropy of etched feature profiles by preventing lateral etching of SiGe. Etch results with a C 4F8/Ar/N2 gas mixture show a straight sidewall profile through the layers of the heterostructure. © 2007 American Vacuum Society.

关键词： Plasma etching

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