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https://www.readbyqxmd.com/read/28102960/nine-degrees-of-freedom-flexmap-for-a-cone-beam-computed-tomography-imaging-device-with-independently-movable-source-and-detector
#1
Peter Keuschnigg, Daniel Kellner, Karl Fritscher, Andrea Zechner, Ulrich Mayer, Philipp Huber, Felix Sedlmayer, Heinz Deutschmann, Philipp Steininger
PURPOSE: Couch-mounted cone-beam computed tomography (CBCT) imaging devices with independently rotatable x-ray source and flat-panel detector arms for acquisitions of arbitrary regions of interest (ROI) have recently been introduced in image-guided radiotherapy (IGRT). This work analyzes mechanical limitations and gravity-induced effects influencing the geometric accuracy of images acquired with arbitrary angular constellations of source and detector in nonisocentric trajectories, which is considered essential for IGRT...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102951/direct-and-fast-measurement-of-ct-beam-filter-profiles-with-simultaneous-geometrical-calibration
#2
Kai Yang, Xinhua Li, X George Xu, Bob Liu
PURPOSE: To accurately measure the beam filter profiles from a variety of CT scanner models and to provide reference data for Monte Carlo simulations of CT scanners. METHODS: This study proposed a new method to measure CT beam filter profiles using a linear-array x-ray detector (X-Scan 0.8f3-512; Detection Technology Inc., Espoo, Finland) under gantry rotation mode. A robust geometrical calibration approach was developed to determine key geometrical parameters by considering the x-ray focal spot location relative to the linear-array detector and the gantry's angular increment at each acquisition point...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102949/simultaneous-pet-mr-imaging-with-a-radio-frequency-penetrable-pet-insert
#3
Alexander M Grant, Brian J Lee, Chen-Ming Chang, Craig S Levin
PURPOSE: A brain sized radio frequency (RF)-penetrable PET insert has been designed for simultaneous operation with MRI systems. This system takes advantage of electro-optical coupling and battery power to electrically float the PET insert relative to the MRI ground, permitting RF signals to be transmitted through small gaps between the modules that form the PET ring. This design facilitates the use of the built-in body coil for RF transmission and thus could be inserted into any existing MR site wishing to achieve simultaneous PET/MR imaging...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102948/use-of-parallel-plate-ionization-chambers-in-reference-dosimetry-of-novac-and-liac-%C3%A2-mobile-electron-linear-accelerators-for-intraoperative-radiotherapy-a-multi-center-survey
#4
Paolo Scalchi, Alessia Ciccotelli, Giuseppe Felici, Assunta Petrucci, Raffaella Massafra, Valeria Piazzi, Paola D'Avenia, Francesca Cavagnetto, Federica Cattani, Raffaella Romagnoli, Antonella Soriani
PURPOSE: LIAC(®) and NOVAC are two mobile linear accelerators dedicated to intraoperative radiation therapy (IORT), generating electron beams in the energy range of 3-12 MeV. Due to high dose-per-pulse (up to 70 mGy per pulse), in 2003 the Italian National Institute of Health (ISS) stated that "for the measure of dose to water in reference conditions, ionization chambers cannot be employed and no published dosimetry protocol can be used". As a consequence, ferrous sulphate (or, alternatively alanine) dosimetry was recommended...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102946/a-portal-dosimetry-dose-prediction-method-based-on-collapsed-cone-algorithm-using-the-clinical-beam-model
#5
J Martínez Ortega, N Gómez González, P Castro Tejero, M Pinto Monedero, N B Tolani, L Núñez Martín, R Sánchez Montero
PURPOSE: Amorphous silicon electronical portal imaging devices (EPIDs) are widely used for dosimetric measurements in Radiation Therapy. The purpose of this work was to determine if a portal dose prediction method can be utilized for dose map calculations based on the linear accelerator model within a commercial treatment planning system (Pinnacle(3) v8.0 m). METHODS: The method was developed for a 6 MV photon beam on the Varian Clinac 21-EX, at a nominal dose rate of 400 MU/min...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102285/non-destructive-study-of-bulk-crystallinity-and-elemental-composition-of-natural-gold-single-crystal-samples-by-energy-resolved-neutron-imaging
#6
Anton S Tremsin, John Rakovan, Takenao Shinohara, Winfried Kockelmann, Adrian S Losko, Sven C Vogel
Energy-resolved neutron imaging enables non-destructive analyses of bulk structure and elemental composition, which can be resolved with high spatial resolution at bright pulsed spallation neutron sources due to recent developments and improvements of neutron counting detectors. This technique, suitable for many applications, is demonstrated here with a specific study of ~5-10 mm thick natural gold samples. Through the analysis of neutron absorption resonances the spatial distribution of palladium (with average elemental concentration of ~0...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28102239/subcycle-quantum-electrodynamics
#7
C Riek, P Sulzer, M Seeger, A S Moskalenko, G Burkard, D V Seletskiy, A Leitenstorfer
Squeezed states of electromagnetic radiation have quantum fluctuations below those of the vacuum field. They offer a unique resource for quantum information systems and precision metrology, including gravitational wave detectors, which require unprecedented sensitivity. Since the first experiments on this non-classical form of light, quantum analysis has been based on homodyning techniques and photon correlation measurements. These methods currently function in the visible to near-infrared and microwave spectral ranges...
January 18, 2017: Nature
https://www.readbyqxmd.com/read/28101932/amino-acid-profiling-of-zinc-resistant-prostate-cancer-cell-lines-associations-with-cancer-progression
#8
Monika Kratochvilova, Martina Raudenska, Zbynek Heger, Lukas Richtera, Natalia Cernei, Vojtech Adam, Petr Babula, Marie Novakova, Michal Masarik, Jaromir Gumulec
BACKGROUND: Failure in intracellular zinc accumulation is a key process in prostate carcinogenesis. Nevertheless, epidemiological studies of zinc administration have provided contradicting results. In order to examine the impact of the artificial intracellular increase of zinc(II) ions on prostate cancer metabolism, PNT1A, 22Rv1, and PC-3 prostatic cell lines-depicting different stages of cancer progression-and their zinc-resistant counterparts were used. To determine "benign" and "malignant" metabolic profiles, amino acid patterns, gene expression, and antioxidant capacity of these cell lines were assessed...
January 19, 2017: Prostate
https://www.readbyqxmd.com/read/28101411/simultaneous-multimodal-ophthalmic-imaging-using-swept-source-spectrally-encoded-scanning-laser-ophthalmoscopy-and-optical-coherence-tomography
#9
Joseph D Malone, Mohamed T El-Haddad, Ivan Bozic, Logan A Tye, Lucas Majeau, Nicolas Godbout, Andrew M Rollins, Caroline Boudoux, Karen M Joos, Shriji N Patel, Yuankai K Tao
Scanning laser ophthalmoscopy (SLO) benefits diagnostic imaging and therapeutic guidance by allowing for high-speed en face imaging of retinal structures. When combined with optical coherence tomography (OCT), SLO enables real-time aiming and retinal tracking and provides complementary information for post-acquisition volumetric co-registration, bulk motion compensation, and averaging. However, multimodality SLO-OCT systems generally require dedicated light sources, scanners, relay optics, detectors, and additional digitization and synchronization electronics, which increase system complexity...
January 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28100783/dual-functional-roles-of-molecular-beacon-a-microrna-detector-and-inhibitor
#10
Wai Ming Li, Ching-Man Chan, Andrew L Miller, Chow H Lee
MicroRNAs are essential in many cellular processes. The ability to detect microRNAs is important for understanding its function and biogenesis. This study is aimed at using a molecular beacon to detect miR-430 in developing zebrafish embryos as a proof of principle. miR-430 is crucial for the clearance of maternal mRNA during maternal zygotic transition (MZT) in embryonic development. Despite its known function, the temporal and spatial expression of miR-430 remains unclear. We used various imaging techniques, including laser scanning confocal microscopy, spinning disk and lightsheet microscopy, to study the localization of miR-430 and any developmental defects possibly caused by the molecular beacon...
January 18, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28100743/three-small-receptive-field-ganglion-cells-in-the-mouse-retina-are-distinctly-tuned-to-size-speed-and-object-motion
#11
Jason Jacoby, Gregory W Schwartz
: Retinal ganglion cells (RGCs) are frequently divided into functional types by their ability to extract and relay specific features from a visual scene, such as the capacity to discern local or global motion, direction of motion, stimulus orientation, contrast or uniformity, or the presence of large or small objects. Here we introduce three previously uncharacterized, nondirection-selective ON-OFF RGC types that represent a distinct set of feature detectors in the mouse retina. The three high-definition (HD) RGCs possess small receptive-field centers and strong surround suppression...
January 18, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28100671/fast-neutron-survey-with-compact-plastic-scintillation-detectors
#12
Rhys M Preston, James R Tickner
With the rise of the Silicon Photomultiplier (SiPM), it is now practical to build compact scintillation detectors well suited to portable use. A prototype survey meter for fast-neutrons and gamma-rays, based around an EJ-299-34 plastic scintillator with SiPM readout, has been developed and tested. A custom digital pulse processor was used to perform pulse shape discrimination on-the-fly. Ambient dose equivalent H*(10) was calculated by means of two energy-dependent 'G-functions'. The sensitivity was calculated to be between 0...
January 17, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28100670/two-new-single-exposure-multi-detector-neutron-spectrometers-for-radiation-protection-applications-in-workplace-monitoring
#13
J M Gómez-Ros, R Bedogni, D Bortot, C Domingo, A Esposito, M V Introini, M Lorenzoli, G Mazzitelli, M Moraleda, A Pola, D Sacco
This communication describes two new instruments, based on multiple active thermal neutron detectors arranged within a single moderator, that permit to unfold the neutron spectrum (from thermal to hundreds of MeV) and to determine the corresponding integral quantities with only one exposure. This makes them especially advantageous for neutron field characterisation and workplace monitoring in neutron-producing facilities. One of the devices has spherical geometry and nearly isotropic response, the other one has cylindrical symmetry and it is only sensitive to neutrons incident along the cylinder axis...
January 17, 2017: Radiation Protection Dosimetry
https://www.readbyqxmd.com/read/28100661/weak-beam-scanning-transmission-electron-microscopy-for-quantitative-dislocation-density-measurement-in-steels
#14
Kenta Yoshida, Masaki Shimodaira, Takeshi Toyama, Yasuo Shimizu, Koji Inoue, Toshimasa Yoshiie, Konstantinovic J Milan, Robert Gerard, Yasuyoshi Nagai
To evaluate dislocations induced by neutron irradiation, we developed a weak-beam scanning transmission electron microscopy (WB-STEM) system by installing a novel beam selector, an annular detector, a high-speed CCD camera and an imaging filter in the camera chamber of a spherical aberration-corrected transmission electron microscope. The capabilities of the WB-STEM with respect to wide-view imaging, real-time diffraction monitoring and multi-contrast imaging are demonstrated using typical reactor pressure vessel steel that had been used in an European nuclear reactor for 30 years as a surveillance test piece with a fluence of 1...
January 17, 2017: Microscopy
https://www.readbyqxmd.com/read/28099995/technical-note-fast-respiratory-motion-estimation-using-sorted-singles-without-unlist-processing-a-feasibility-study
#15
Jaewon Yang, Mehdi Khalighi, Thomas A Hope, Karen Ordovas, Youngho Seo
PURPOSE: The study aims to demonstrate the feasibility of fast respiratory motion estimation using singles data available as a sorted format in list-mode files acquired in an integrated PET/MRI system for a proof-of-concept. METHODS: The derivation of SDRM is enabled by singles recorded and binned by second for each detector crystal in PET list-mode data acquired in a SIGNA PET/MR. The proposed method is to derive a SDRM trace by summing up all singles from all detectors through the PET data acquisition...
January 18, 2017: Medical Physics
https://www.readbyqxmd.com/read/28099963/low-molecular-weight-hydrophilic-and-lipophilic-antioxidants-in-nonmelanoma-skin-carcinomas-and-adjacent-normal-looking-skin
#16
Konstantina Grammenandi, Maria Kyriazi, Alexandra Katsarou-Katsari, Othon Papadopoulos, Ioanna Anastassopoulou, Georgios T Papaioannou, Alexandros Sagriotis, Michail Rallis, Howard I Maibach
Low-molecular-weight antioxidants are some of the most efficient agents of the skin defense mechanism against environmental factors, such as cosmic rays, smoke, and pollutants. The total skin concentrations of hydrophilic ascorbic and uric acids, as well as lipophilic α-tocopherol, β-carotene, and ubiquinol-10 antioxidants were determined by an HPLC-EC detector from 18 biopsies of human nonmelanoma skin carcinomas and 18 biopsies from skin areas adjacent to carcinomas. No significant differences in the concentrations of lipophilic antioxidants in both carcinomas and normal-looking skin areas adjacent to carcinomas were observed...
January 19, 2017: Skin Pharmacology and Physiology
https://www.readbyqxmd.com/read/28099958/distance-from-left-renal-vein-to-inferior-pancreaticoduodenal-artery-a-landmark-for-identifying-inferior-pancreaticoduodenal-artery-in-pancreatoduodenectomy
#17
Yoshito Tomimaru, Kaishu Tanaka, Kozo Noguchi, Hisanori Hatano, Hidetoshi Eguchi, Keizo Dono
BACKGROUND/AIM: During pancreatoduodenectomy, early ligation of major afferent arteries to pancreatic head prior to dissection of the corresponding veins may reduce intraoperative bleeding. Inferior pancreaticoduodenal artery (IPDA), one of the major afferent arteries, is difficult to identify. We measured the distance from left renal vein to IPDA based on preoperative multi-detector row computed tomography (MDCT) images for use as a new landmark for IPDA. METHODS: The distance between left renal vein and IPDA was measured in 417 patients using MDCT images...
January 19, 2017: Digestive Surgery
https://www.readbyqxmd.com/read/28099158/single-transmission-line-readout-method-for-silicon-photomultiplier-based-time-of-flight-and-depth-of-interaction-pet
#18
Guen Bae Ko, Jae Sung Lee
We propose a novel single transmission-line readout method for whole-body time-of-flight positron emission tomography applications, without compromising on performance. The basic idea of the proposed multiplexing method is the addition of a specially prepared tag signal ahead of the scintillation pulse. The tag signal is a square pulse that encodes photon arrival time and channel information. The two-dimensional position of a silicon photomultiplier (SiPM) array is encoded by the specific width and height of the tag signal...
January 18, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28099156/quasi-monochromatic-imaging-in-x-ray-ct-via-spectral-deconvolution-using-photon-counting-detectors
#19
Sen Wang, Li Zhang, Dufan Wu, Xiaofei Xu
Photon counting detectors can obtain the spectral information of incident x-ray spectrum while the detected counts may differ from the incident counts due to detector response. If uncorrected or uncompensated, the response will lead to distortion in CT reconstruction. With the intention of reducing the distortion and exploring the potential of photon counting detectors, a novel reconstruction strategy with spectral deconvolution is proposed in this paper which attempts to set itself apart from traditional material decomposition framework...
January 18, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28098847/polish-yellow-sweet-clover-melilotus-officinalis-l-honey-chromatographic-fingerprints-and-chemical-markers
#20
Izabela Jasicka-Misiak, Ewa Makowicz, Natalia Stanek
A case study of Polish Melilotus officinalis honey was presented for the first time. Gas chromatography-mass spectrometry (GC-MS) (after steam distillation, Soxhlet extraction, ultrasonic solvent extraction, and solid phase extraction (SPE)) and targeted high performance liquid chromatography with a photodiode array detector (HPLC-PAD) were applied to determine the characteristic components of honey. While ubiquitous in most honeys, carbohydrates, terpene derivatives, and phenylacetic acid dominated in the Soxhlet extracts (25...
January 15, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
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