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https://www.readbyqxmd.com/read/29766603/characterization-of-aerosol-nitroaromatic-compounds-validation-of-an-experimental-method
#1
Mohammed Jaoui, Michael Lewandowski, John H Offenberg, Maribel Colon, Kenneth S Docherty, Tadeusz E Kleindienst
The analytical capabilities associated with the use of silylation reactions have been extended to a new class of organic molecules, nitroaromatic compounds (NACs). These compounds are a possible contributor to urban particulate matter of secondary origin which would make them important analytes due to their (1) detrimental health effects, (2) potential to affect aerosol optical properties, (3) and usefulness for identifying PM2.5 from biomass burning. The technique is based on derivatization of the parent NACs using N,O-bis-(trimethylsilyl)-trifluoro acetamide, one of the most prevalent derivatization reagent for analyzing hydroxylated molecules, followed by GC-MS using electron ionization (EI) and methane chemical ionization (CI)...
May 15, 2018: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/29765695/influence-of-high-altitude-on-the-burning-behaviour-of-typical-combustibles-and-the-related-responses-of-smoke-detectors-in-compartments
#2
Ran Tu, Yi Zeng, Jun Fang, Yong-Ming Zhang
The effect of altitude on typical combustible burning and related smoke detector response signals was investigated by comparison experiments at altitudes of 40 m and 3650 m based on EN54 standard tests. Point-type light scattering photoelectric smoke detectors and ionization smoke detectors were used for four kinds of EN54 fire tests, including two kinds of smouldering fires with wood (test fire no. 2 in EN54 standard or TF2) and cotton (TF3), and two kinds of flaming fires with polyurethane (TF4) and n -heptane (TF5)...
April 2018: Royal Society Open Science
https://www.readbyqxmd.com/read/29762130/ionization-chamber-correction-factors-for-mr-linacs
#3
Stefan Pojtinger, Oliver Steffen Dohm, Ralf-Peter Kapsch, Daniela Thorwarth

 Previously, readings of air-filled ionization chambers have been described as being influenced by magnetic fields. To use these chambers for dosimetry in magnetic resonance guided radiotherapy (MRgRT), this effect must be taken into account by introducing a correction factor kB.
 The purpose of this study is to systematically investigate kB for a typical reference setup for commercially available ionization chambers with different magnetic field strengths.
 
 Material and Methods:
 The Monte Carlo simulation tool EGSnrc was used to simulate eight commercially available ionization chambers in magnetic fields whose magnetic flux density was in the range of 0 to 2...
May 15, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29759487/clinical-examination-of-proton-pencil-beam-scanning-on-a-moving-anthropomorphic-lung-phantom
#4
Peng Wang, Shikui Tang, Paige A Taylor, David E Cummings, Martin Janson, Erik Traneus, Jared D Sturgeon, Andrew K Lee, Chang Chang
The objective of this study was to examine the use of proton pencil beam scanning for the treatment of moving lung tumors. A single-field uniform dose proton pencil beam scanning (PBS) plan was generated for the standard thorax phantom designed by the Imaging and Radiation Oncology Core (IROC) Houston QA Center. Robust optimization, including range and setup uncertainties as well as volumetric repainting, was used for the plan. Patient-specific quality assurance (QA) measurements were performed using both a water tank and a custom heterogeneous QA phantom...
May 11, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/29737969/topas-geant4-configuration-for-ionization-chamber-calculations-in-proton-beams
#5
Jörg Wulff, Kilian-Simon Baumann, Nico Gerd Verbeek, Christian Baeumer, Beate Timmermann, Klemens Zink
Geant4 - as used in TOPAS - is one of the major general purpose codes suitable for investigation of ionization chambers in proton beams. To provide reliable results, the impact of parameter settings and possible limitations of the underlying condensed history (CH) algorithm need to be known.
 A version of the Fano cavity test was implemented in Geant4 (10.03.p1) for protons, which allows comparison of calculation with expected result for a typical ionization chamber-like geometry. Parameters of the CH implementation in the EMStandardOpt4 physics-list were tested...
May 8, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29729878/2018-acc-hrs-nasci-scai-scct-expert-consensus-document-on-optimal-use-of-ionizing-radiation-in-cardiovascular-imaging-best-practices-for-safety-and-effectiveness-part-2-radiological-equipment-operation-dose-sparing-methodologies-patient-and-medical-personnel
#6
John W Hirshfeld, Victor A Ferrari, Frank M Bengel, Lisa Bergersen, Charles E Chambers, Andrew J Einstein, Mark J Eisenberg, Mark A Fogel, Thomas C Gerber, David E Haines, Warren K Laskey, Marian C Limacher, Kenneth J Nichols, Daniel A Pryma, Gilbert L Raff, Geoffrey D Rubin, Donnette Smith, Arthur E Stillman, Suma A Thomas, Thomas T Tsai, Louis K Wagner, L Samuel Wann
No abstract text is available yet for this article.
April 30, 2018: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/29729877/2018-acc-hrs-nasci-scai-scct-expert-consensus-document-on-optimal-use-of-ionizing-radiation-in-cardiovascular-imaging-best-practices-for-safety-and-effectiveness-a-report-of-the-american-college-of-cardiology-task-force-on-expert-consensus-decision-pathways
#7
John W Hirshfeld, Victor A Ferrari, Frank M Bengel, Lisa Bergersen, Charles E Chambers, Andrew J Einstein, Mark J Eisenberg, Mark A Fogel, Thomas C Gerber, David E Haines, Warren K Laskey, Marian C Limacher, Kenneth J Nichols, Daniel A Pryma, Gilbert L Raff, Geoffrey D Rubin, Donnette Smith, Arthur E Stillman, Suma A Thomas, Thomas T Tsai, Louis K Wagner, L Samuel Wann
No abstract text is available yet for this article.
April 30, 2018: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/29729876/2018-acc-hrs-nasci-scai-scct-expert-consensus-document-on-optimal-use-of-ionizing-radiation-in-cardiovascular-imaging-best-practices-for-safety-and-effectiveness-part-1-radiation-physics-and-radiation-biology
#8
John W Hirshfeld, Victor A Ferrari, Frank M Bengel, Lisa Bergersen, Charles E Chambers, Andrew J Einstein, Mark J Eisenberg, Mark A Fogel, Thomas C Gerber, David E Haines, Warren K Laskey, Marian C Limacher, Kenneth J Nichols, Daniel A Pryma, Gilbert L Raff, Geoffrey D Rubin, Donnette Smith, Arthur E Stillman, Suma A Thomas, Thomas T Tsai, Louis K Wagner, L Samuel Wann
No abstract text is available yet for this article.
April 30, 2018: Journal of the American College of Cardiology
https://www.readbyqxmd.com/read/29726409/correction-factors-for-ionization-chamber-measurements-with-the-quot-valencia-quot-and-quot-large-field-valencia-quot-brachytherapy-applicators
#9
Vicent Gimenez-Alventosa, Vicente Gimenez, Facundo Ballester, Javier Vijande, Pedro Andreo
Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the ``Valencia'' and ``Large Field Valencia'' shielded applicators...
May 4, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29716341/erratum-a-combined-segmented-anode-gas-ionization-chamber-and-time-of-flight-detector-for-heavy-ion-elastic-recoil-detection-analysis-rev-sci-instrum-87-103303-2016
#10
Petter Ström, Per Petersson, Marek Rubel, Göran Possnert
No abstract text is available yet for this article.
April 2018: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29714194/synchrotron-x-ray-microbeam-dosimetry-with-a-20-micrometre-resolution-scintillator-fibre-optic-dosimeter
#11
James Archer, Enbang Li, Marco Petasecca, Andrew Stevenson, Jayde Livingstone, Andrew Dipuglia, Jeremy Davis, Anatoly Rosenfeld, Michael Lerch
Cancer is one of the leading causes of death worldwide. External beam radiation therapy is one of the most important modalities for the treatment of cancers. Synchrotron microbeam radiation therapy (MRT) is a novel pre-clinical therapy that uses highly spatially fractionated X-ray beams to target tumours, allowing doses much higher than conventional radiotherapies to be delivered. A dosimeter with a high spatial resolution is required to provide the appropriate quality assurance for MRT. This work presents a plastic scintillator fibre optic dosimeter with a one-dimensional spatial resolution of 20 µm, an improvement on the dosimeter with a resolution of 50 µm that was demonstrated in previous work...
May 1, 2018: Journal of Synchrotron Radiation
https://www.readbyqxmd.com/read/29704440/development-and-implementation-of-epid-based-quality-assurance-tests-for-the-small-animal-radiation-research-platform-sarrp
#12
Akbar Anvari, Yannick Poirier, Amit Sawant
PURPOSE: Although small animal image-guided radiotherapy (SA-IGRT) systems are used increasingly in preclinical research, tools for performing routine quality assurance (QA) have not been optimized and are not readily available. Robust, efficient, and reliable QA tools are needed to ensure the accuracy and reproducibility of SA-IGRT systems. Several investigators have reported custom-made phantoms and protocols for SA-IGRT systems QA. These are typically time and resource intensive and are therefore not well suited to the preclinical radiotherapy environment, in which physics support is limited and routine QA is performed by technical staff...
April 28, 2018: Medical Physics
https://www.readbyqxmd.com/read/29701998/importance-of-dosimetry-protocol-for-cell-irradiation-on-a-low-x-rays-facility-and-consequences-for-the-biological-response
#13
M Dos Santos, V Paget, M Ben Kacem, F Trompier, M Benadjaoud, A François, O Guipaud, M Benderitter, F Milliat
PURPOSE: The main objective of radiobiology is to establish links between doses and radiation-induced biological effects. In this context, well-defined dosimetry protocols are crucial to the determination of experimental protocols. This work proposes a new dosimetry protocol for cell irradiation in a SARRP and shows the importance of the modification of some parameters defined in dosimetry protocol for physical dose and biological outcomes. MATERIALS AND METHODS: Once all parameters of the configuration were defined, dosimetry measurements with ionization chambers and EBT3 films were performed to evaluate the dose rate and the attenuation due to the cell culture medium...
April 27, 2018: International Journal of Radiation Biology
https://www.readbyqxmd.com/read/29681287/analytical-characteristics-of-nano-electrospray-operated-under-super-atmospheric-pressure
#14
Md Matiur Rahman, Lee Chuin Chen
High-pressure nanoelectrospray ionization (nanoESI) source is a recently developed technique in which the electrospray ionization is generated inside an enclosed chamber with gas pressure higher than the atmospheric pressure. In this paper, the performance of nanoESI under different gas pressures, emitter position, ion inlet temperature, additive for desalination are presented. Under a pressure of 2 bars, the nanoESI is almost eased from the electrical discharge problem, and that offers a wider tuning window for the emitter potential to produces a higher and more stable ion signal...
August 27, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29677677/comparison-of-methods-for-h-10-calculation-from-measured-labr-3-ce-detector-spectra
#15
A Vargas, N Cornejo, A Camp
The Universitat Politecnica de Catalunya (UPC) and the Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT) have evaluated methods based on stripping, conversion coefficients and Maximum Likelihood Estimation using Expectation Maximization (ML-EM) in calculating the H*(10) rates from photon pulse-height spectra acquired with a spectrometric LaBr3 (Ce)(1.5″ × 1.5″) detector. There is a good agreement between results of the different H*(10) rate calculation methods using the spectra measured at the UPC secondary standard calibration laboratory in Barcelona...
March 31, 2018: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/29674084/development-of-a-plug-type-ims-ms-instrument-and-its-applications-in-resolving-problems-existing-in-in-situ-detection-of-illicit-drugs-and-explosives-by-ims
#16
Zhenxia Du, Tangqiang Sun, Jianan Zhao, Di Wang, Zhongxia Zhang, Wenlian Yu
Ion mobility spectrometry (IMS) which acts as a rapid analysis technique is widely used in the field detection of illicit drugs and explosives. Due to limited separation abilities of the pint-sized IMS challenges and problems still exist regarding high false positive and false negative responses due to the interference of the matrix. In addition, the gas-phase ion chemistry and special phenomena in the IMS spectra, such one substance showing two peaks, were not identified unambiguously. In order to explain or resolve these questions, in this paper, an ion mobility spectrometry was coupled to a mass spectrometry (IMS-MS)...
July 1, 2018: Talanta
https://www.readbyqxmd.com/read/29667294/image-quality-and-absorbed-dose-comparison-of-single-and-dual-source-cone-beam-computed-tomography
#17
Hideharu Miura, Shuichi Ozawa, Toshiya Okazue, Atsushi Kawakubo, Kiyoshi Yamada, Yasushi Nagata
PURPOSE: Dual-source cone-beam computed tomography (DCBCT) is currently available in the Vero4DRT image-guided radiotherapy system. We evaluated the image quality and absorbed dose for DCBCT and compared the values with those for single-source CBCT (SCBCT). METHODS: Image uniformity, Hounsfield unit (HU) linearity, image contrast, and spatial resolution were evaluated using a Catphan phantom. The rotation angle for acquiring SCBCT and DCBCT images is 215° and 115°, respectively...
April 17, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29664225/improvement-of-dose-calculation-in-radiation-therapy-due-to-metal-artifact-correction-using-the-augmented-likelihood-image-reconstruction
#18
Christian Ziemann, Maik Stille, Florian Cremers, Thorsten M Buzug, Dirk Rades
BACKGROUND: Metal artifacts caused by high-density implants lead to incorrectly reconstructed Hounsfield units in computed tomography images. This can result in a loss of accuracy in dose calculation in radiation therapy. This study investigates the potential of the metal artifact reduction algorithms, Augmented Likelihood Image Reconstruction and linear interpolation, in improving dose calculation in the presence of metal artifacts. MATERIALS AND METHODS: In order to simulate a pelvis with a double-sided total endoprosthesis, a polymethylmethacrylate phantom was equipped with two steel bars...
April 17, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/29663429/remote-cherenkov-imaging-based-quality-assurance-of-a-magnetic-resonance-image-guided-radiotherapy-system
#19
Jacqueline M Andreozzi, Karen E Mooney, Petr Brůža, Austen Curcuru, David J Gladstone, Brian W Pogue, Olga Green
PURPOSE: Tools to perform regular quality assurance of magnetic resonance image-guided radiotherapy (MR-IGRT) systems should ideally be independent of interference from the magnetic fields. Remotely acquired optical Cherenkov imaging-based dosimetry measurements in water were investigated for this purpose, comparing measures of dose accuracy, temporal dynamics, and overall integrated IMRT delivery. METHODS: A 40x30.5x37.5cm3 water tank doped with 1g/L of quinine sulfate was imaged using an intensified charge coupled device (ICCD) to capture the Cherenkov emission while being irradiated by a commercial MR-IGRT system (ViewRay™ )...
April 16, 2018: Medical Physics
https://www.readbyqxmd.com/read/29660104/development-of-an-ionization-chamber-for-low-and-medium-energy-photon-dosimetry
#20
Sunil K Singh, M S Kulkarni
Measurement of dose due to low and medium energy X-ray using an ionization chamber needs special considerations as the wall thickness of the detector plays an important role in signal generation. A thin and plane wall ionization chamber having 900 cc volume was developed to study its calibration coefficient with air kerma (Kair) rate and ambient dose equivalent (H*(10)) rate at various X-ray beam qualities generated from a dosimetry grade X-ray machine. Optimized ionization chamber wall thickness was determined through measurements where a flat energy response of the ionization chamber could be established...
April 5, 2018: Radiation Protection Dosimetry
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