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https://www.readbyqxmd.com/read/28644913/supplement-2-for-the-2004-update-of-the-aapm-task-group-no-43-report-joint-recommendations-by-the-aapm-and-gec-estro
#1
Mark J Rivard, Facundo Ballester, Wayne M Butler, Larry A DeWerd, Geoffrey S Ibbott, Ali S Meigooni, Christopher S Melhus, Michael G Mitch, Ravinder Nath, Panagiotis Papagiannis
Since publication of the 2004 update to the American Association of Physicists in Medicine (AAPM) Task Group No. 43 Report (TG-43U1) and its 2007 supplement (TG-43U1S1), several new low-energy photon-emitting brachytherapy sources have become available. Many of these sources have satisfied the AAPM prerequisites for routine clinical purposes and are posted on the Brachytherapy Seed Registry managed jointly by the AAPM and the Imaging and Radiation Oncology Core Houston Quality Assurance Center (IROC Houston)...
June 23, 2017: Medical Physics
https://www.readbyqxmd.com/read/28643024/automatic-seed-picking-for-brachytherapy-postimplant-validation-with-3d-ct-images
#2
Guobin Zhang, Qiyuan Sun, Shan Jiang, Zhiyong Yang, Xiaodong Ma, Haisong Jiang
PURPOSE: Postimplant validation is an indispensable part in the brachytherapy technique. It provides the necessary feedback to ensure the quality of operation. The ability to pick implanted seed relates directly to the accuracy of validation. To address it, an automatic approach is proposed for picking implanted brachytherapy seeds in 3D CT images. METHODS: In order to pick seed configuration (location and orientation) efficiently, the approach starts with the segmentation of seed from CT images using a thresholding filter which based on gray-level histogram...
June 22, 2017: International Journal of Computer Assisted Radiology and Surgery
https://www.readbyqxmd.com/read/28630886/review-of-the-current-status-of-radiation-protection-in-diagnostic-radiology-in-africa
#3
REVIEW
Wilbroad Muhogora, Madan M Rehani
The aim of this paper is to review the available published studies from African countries on patient doses and medical radiation protection and identify strengths, weaknesses, and challenges. Papers on radiation doses to patients published until 2016 pertaining to studies in African countries were reviewed. Radiography, interventional radiology, computed tomography (CT), and mammography modalities were covered. In radiography, the entrance surface air kerma values were below the established diagnostic reference levels (DRLs) provided by the International Atomic Energy Agency, European Commission, and National Council on Radiation Protection and Measurements...
July 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/28615985/treatment-of-movement-disorders-with-focused-ultrasound
#4
REVIEW
Paul S Fishman, Victor Frenkel
Although the use of ultrasound as a potential therapeutic modality in the brain has been under study for several decades, relatively few neuroscientists or neurologists are familiar with this technology. Stereotactic brain lesioning had been widely used as a treatment for medically refractory patients with essential tremor (ET), Parkinson disease (PD), and dystonia but has been largely replaced by deep brain stimulation (DBS) surgery, with advantages both in safety and efficacy. However, DBS is associated with complications including intracerebral hemorrhage, infection, and hardware malfunction...
2017: Journal of Central Nervous System Disease
https://www.readbyqxmd.com/read/28600849/modified-ideal-observer-model-miom-for-high-contrast-and-high-spatial-resolution-ct-imaging-tasks
#5
Juan P Cruz-Bastida, Daniel Gomez-Cardona, John Garrett, Timothy Szczykutowicz, Guang-Hong Chen, Ke Li
PURPOSE: Although a variety of mathematical observer models have been developed to predict human observer performance for low contrast lesion detection tasks, their predictive power for high contrast and high spatial resolution discrimination imaging tasks, including those in CT bone imaging, could be limited. The purpose of this work was to develop a modified observer model that has improved correlation with human observer performance for these tasks. METHODS: The proposed observer model, referred to as the modified ideal observer model (MIOM), uses a weight function to penalize components in the task function that have less contribution to the actual human observer performance for high contrast and high spatial resolution discrimination tasks...
June 10, 2017: Medical Physics
https://www.readbyqxmd.com/read/28592501/a-physicist-s-quest-in-biology-max-delbr%C3%A3-ck-and-complementarity
#6
Bernard S Strauss
Max Delbrück was trained as a physicist but made his major contribution in biology and ultimately shared a Nobel Prize in Physiology or Medicine. He was the acknowledged leader of the founders of molecular biology, yet he failed to achieve his key scientific goals. His ultimate scientific aim was to find evidence for physical laws unique to biology: so-called "complementarity." He never did. The specific problem he initially wanted to solve was the nature of biological replication but the discovery of the mechanism of replication was made by others, in large part because of his disdain for the details of biochemistry...
June 2017: Genetics
https://www.readbyqxmd.com/read/28590712/structural-characterization-of-intermetallic-compounds-by-27-al-solid-state-nmr-spectroscopy
#7
Christopher Benndorf, Hellmut Eckert, Oliver Janka
Intermetallic compounds are of broad interest for solid state chemists, condensed matter physicists, and material scientists due to their intriguing crystal chemistry, their physical properties, and their potential applications, ranging from lab curiosities to everyday objects. To characterize and understand the properties of new compounds and novel materials, the availability of structural information, particularly single-crystal X-ray diffraction data, is a mandatory prerequisite. Especially when it comes to the formation of compounds with deficient or mixed site occupancies, superstructures, or representatives crystallizing in other, thus far unknown structure types, a complementary method for structural analysis is of great value...
June 7, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28590470/an-engineering-design-approach-to-systems-biology
#8
REVIEW
Kevin A Janes, Preethi L Chandran, Roseanne M Ford, Matthew J Lazzara, Jason A Papin, Shayn M Peirce, Jeffrey J Saucerman, Douglas A Lauffenburger
Measuring and modeling the integrated behavior of biomolecular-cellular networks is central to systems biology. Over several decades, systems biology has been shaped by quantitative biologists, physicists, mathematicians, and engineers in different ways. However, the basic and applied versions of systems biology are not typically distinguished, which blurs the separate aspirations of the field and its potential for real-world impact. Here, we articulate an engineering approach to systems biology, which applies educational philosophy, engineering design, and predictive models to solve contemporary problems in an age of biomedical Big Data...
June 7, 2017: Integrative Biology: Quantitative Biosciences From Nano to Macro
https://www.readbyqxmd.com/read/28587053/quantitative-approach-to-failure-mode-and-effect-analysis-for-linear-accelerator-quality-assurance
#9
Jennifer C O'Daniel, Fang-Fang Yin
PURPOSE: To determine clinic-specific linear accelerator quality assurance (QA) TG-142 test frequencies, to maximize physicist time efficiency and patient treatment quality. METHODS AND MATERIALS: A novel quantitative approach to failure mode and effect analysis is proposed. Nine linear accelerator-years of QA records provided data on failure occurrence rates. The severity of test failure was modeled by introducing corresponding errors into head and neck intensity modulated radiation therapy treatment plans...
May 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28586959/the-ever-evolving-role-of-the-academic-clinical-physicist
#10
EDITORIAL
Eric E Klein, Jonas Fontenot, Nesrin Dogan
No abstract text is available yet for this article.
May 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28585724/assessment-of-volumetric-absorbed-dose-for-mobile-fluoroscopic-3d-image-acquisition
#11
Stephanie Leon
Mobile fluoroscopy (c-arm) units offering 3D image reconstruction are becoming more common in surgical settings. Although these images are "CT-like" and sometimes replace the postoperative CT, the acquisition is technically very different from a traditional CT acquisition. Dose assessment is complicated by a large beam width, automatic exposure rate control, and a rotation of less than 360°. The purpose of this work was to explore the impact of these factors on the volumetric dose calculation and to provide practical recommendations for clinical physicists assessing dose from these units using commonly available equipment...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28576581/in-vivo-dosimetry-for-lung-radiotherapy-including-sbrt
#12
REVIEW
Boyd M C McCurdy, Peter M McCowan
SBRT for lung cancer is being rapidly adopted as a treatment option in modern radiotherapy centres. This treatment is one of the most complex in common clinical use, requiring significant expertise and resources. It delivers a high dose per fraction (typically ∼6-30Gy/fraction) over few fractions. The complexity and high dose delivered in only a few fractions make powerful arguments for the application of in vivo dosimetry methods for these treatments to enhance patient safety. In vivo dosimetry is a group of techniques with a common objective - to estimate the dose delivered to the patient through a direct measurement of the treatment beam(s)...
May 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28573677/physical-properties-of-the-chromosomes-and-implications-for-development
#13
REVIEW
Takeshi Sugawara, Akatsuki Kimura
Remarkable progress has been made in understanding chromosome structures inside the cell nucleus. Recent advances in Hi-C technologies enable the detection of genome-wide chromatin interactions, providing insight into three-dimensional (3D) genome organization. Advancements in the spatial and temporal resolutions of imaging as well as in molecular biological techniques allow the tracking of specific chromosomal loci, improving our understanding of chromosome movements. From these data, we are beginning to understand how the intra-nuclear locations of chromatin loci and the 3D genome structure change during development and differentiation...
June 2, 2017: Development, Growth & Differentiation
https://www.readbyqxmd.com/read/28573270/hybrid-colloidal-microswimmers-through-sequential-capillary-assembly
#14
Songbo Ni, Emanuele Marini, Ivo Buttinoni, Heiko Wolf, Lucio Isa
Active colloids, also known as artificial microswimmers, are self-propelled micro- and nanoparticles that convert uniform sources of fuel (e.g. chemical) or uniform external driving fields (e.g. magnetic or electric) into directed motion by virtue of asymmetry in their shape or composition. These materials are currently attracting enormous scientific attention as models for out-of-equilibrium systems and with the promise to be used as micro- and nanoscale devices. However, current fabrication of active colloids is limited in the choice of available materials, geometries, and modes of motion...
June 14, 2017: Soft Matter
https://www.readbyqxmd.com/read/28561894/texture-and-breakdown-in-the-mouth-an-industrial-research-approach
#15
REVIEW
Peter Lillford
Texture is one of foods' most important qualities, but is a sensory perception by consumers. To understand, predict and design for sensory appeal, we must codify the sensory response and diagnose the physical stimuli in the mouth which give rise to perception. This brief review examines the leading contributions from Szczesniak and Bourne and shows the developments in the field, built upon their earlier contributions. Because of its importance to consumer appeal, the food industry has made significant contributions...
May 31, 2017: Journal of Texture Studies
https://www.readbyqxmd.com/read/28555878/correlation-between-a-2d-channelized-hotelling-observer-and-human-observers-in-a-low-contrast-detection-task-with-multi-slice-reading-in-ct
#16
Lifeng Yu, Baiyu Chen, James M Kofler, Christopher P Favazza, Shuai Leng, Matthew A Kupinski, Cynthia H McCollough
PURPOSE: Model observers have been successfully developed and used to assess the quality of static 2D CT images. However, radiologists typically read images by paging through multiple 2D slices (i.e. multi-slice reading). The purpose of this study was to correlate human and model observer performance in a low-contrast detection task performed using both 2D and multi-slice reading, and to determine if the 2D model observer still correlate well with human observer performance in multi-slice reading...
May 27, 2017: Medical Physics
https://www.readbyqxmd.com/read/28548315/aapm-medical-physics-practice-guideline-8-a-linear-accelerator-performance-tests
#17
Koren Smith, Peter Balter, John Duhon, Gerald A White, David L Vassy, Robin A Miller, Christopher F Serago, Lynne A Fairobent
PURPOSE: The purpose of this guideline is to provide a list of critical performance tests in order to assist the Qualified Medical Physicist (QMP) in establishing and maintaining a safe and effective quality assurance (QA) program. The performance tests on a linear accelerator (linac) should be selected to fit the clinical patterns of use of the accelerator and care should be given to perform tests which are relevant to detecting errors related to the specific use of the accelerator. METHODS: A risk assessment was performed on tests from current task group reports on linac QA to highlight those tests that are most effective at maintaining safety and quality for the patient...
May 26, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28536784/paul-henry-latimer-1925-2011-discoverer-of-selective-scattering-in-photosynthetic-systems
#18
Margaret Gwyn Latimer, Thomas T Bannister, Govindjee
We provide here a brief tribute to Paul Henry Latimer (November 25, 1925 to October 1, 2011), a dedicated biological physicist, discoverer of selective scattering in biological systems, a wonderful teacher, husband, and father. We provide here a glimpse of his personal and professional life, including reminiscences from F. Dudley Bryant, Dan A. Cross, Bobby E. Pyle, Bryan L. Seiber, and Bruce A. Seiber.
May 23, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28516046/image-quality-assessment-of-a-1-5t-dedicated-magnetic-resonance-simulator-for-radiotherapy-with-a-flexible-radio-frequency-coil-setting-using-the-standard-american-college-of-radiology-magnetic-resonance-imaging-phantom-test
#19
Oi Lei Wong, Jing Yuan, Siu Ki Yu, Kin Yin Cheung
BACKGROUND: A flexible RF coil setting has to be used on an MR-simulator (MR-sim) in the head and neck simulation scan for radiotherapy (RT) purpose, while the image quality might be compromised due to the sub-optimized flexible coil compared to the normal diagnostic radiological (DR) head coil. In this study, we assessed the image quality of an MR-sim by conducting the standard American College of Radiology (ACR) MRI phantom test on a 1.5T MR-sim under RT-setting and comparing it to DR-setting...
April 2017: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/28507702/plasmon-induced-charge-separation-chemistry-and-wide-applications
#20
Tetsu Tatsuma, Hiroyasu Nishi, Takuya Ishida
Recent development of nanoplasmonics has stimulated chemists to utilize plasmonic nanomaterials for efficient and distinctive photochemical applications, and physicists to boldly go inside the "wet" chemistry world. The discovery of plasmon-induced charge separation (PICS) has even accelerated these trends. On the other hand, some confusion is found in discussions about PICS. In this perspective, we focus on differences between PICS and some other phenomena such as co-catalysis effect and plasmonic nanoantenna effect...
May 1, 2017: Chemical Science
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