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Radiation physics

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https://www.readbyqxmd.com/read/28731818/the-adron-rm-instrument-onboard-the-exomars-rover
#1
I G Mitrofanov, M L Litvak, S Y Nikiforov, I Jun, Y I Bobrovnitsky, D V Golovin, A S Grebennikov, F S Fedosov, A S Kozyrev, D I Lisov, A V Malakhov, M I Mokrousov, A B Sanin, V N Shvetsov, G N Timoshenko, T M Tomilina, V I Tret'yakov, A A Vostrukhin
This overview presents the physical principles, design, measurement capabilities, and summary of planned operations of the autonomous detector of radiation of neutrons onboard rover at Mars (ADRON-RM) on the surface of Mars. ADRON-RM is a Russian project selected for the joint European Space Agency-Roscosmos ExoMars 2020 landing mission. A compact passive neutron spectrometer, ADRON-RM, was designed to study the abundance and distribution of water and neutron absorption elements (such as Cl, Fe, and others) in the martian subsurface along the path of the ExoMars rover...
June 2017: Astrobiology
https://www.readbyqxmd.com/read/28729224/robotic-placement-of-fenix-continence-restoration-system-in-a-patient-with-previous-radiation-to-the-pelvis-a-case-report
#2
Mariana Espinal, Christopher C DeStephano, Paulami Guha, Shilpa P Gajarawala, Anita H Chen, Paul D Pettit
Fecal incontinence (FI) is a disabling problem affecting women. Conservative treatment includes dietary modification, antimotility agents, and pelvic floor physical therapy. If conservative medical management is unsuccessful, surgical intervention may be required. Surgical options include rectal sphincteroplasty, bulking agent injection, radiofrequency anal sphincter remodeling procedure and sacral nerve stimulation (SNS) therapy. Recently, a new therapy for FI, the FENIX Continence Restoration System has become available...
July 17, 2017: Journal of Minimally Invasive Gynecology
https://www.readbyqxmd.com/read/28726684/low-dose-4d-cone-beam-ct-via-joint-spatiotemporal-regularization-of-tensor-framelet-and-nonlocal-total-variation
#3
Hao Han, Hao Gao, Lei Xing
Excessive radiation exposure is still a major concern in 4D cone-beam computed tomography (4D-CBCT) due to its prolonged scanning duration. Radiation dose can be effectively reduced by either under-sampling the x-ray projections or reducing the x-ray flux. However, 4D-CBCT reconstruction under such low-dose protocols is prone to image artifacts and noise. In this work, we propose a novel joint regularization-based iterative reconstruction method for low-dose 4D-CBCT. To tackle the under-sampling problem, we employ spatiotemporal tensor framelet (STF) regularization to take advantage of the spatiotemporal coherence of the patient anatomy in 4D images...
July 20, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28723273/the-repair-project-examining-the-biological-impacts-of-sub-background-radiation-exposure-within-snolab-a-deep-underground-laboratory
#4
Christopher Thome, Sujeenthar Tharmalingam, Jake Pirkkanen, Andrew Zarnke, Taylor Laframboise, Douglas R Boreham
Considerable attention has been given to understanding the biological effects of low-dose ionizing radiation exposure at levels slightly above background. However, relatively few studies have been performed to examine the inverse, where natural background radiation is removed. The limited available data suggest that organisms exposed to sub-background radiation environments undergo reduced growth and an impaired capacity to repair genetic damage. Shielding from background radiation is inherently difficult due to high-energy cosmic radiation...
July 19, 2017: Radiation Research
https://www.readbyqxmd.com/read/28721886/effect-of-eischens-yoga-during-radiation-therapy-on-prostate-cancer-patient-symptoms-and-quality-of-life-a-randomized-phase-ii-trial
#5
Avital Mazar Ben-Josef, Jerry Chen, Paul Wileyto, Abigail Doucette, Justin Bekelman, John Christodouleas, Curtiland Deville, Neha Vapiwala
PURPOSE: A randomized phase II study was performed to measure the potential therapeutic effects of yoga on fatigue, erectile dysfunction, urinary incontinence, and overall quality of life (QOL) in prostate cancer (PCa) patients undergoing external beam radiation therapy (RT). METHODS AND MATERIALS: The participants were randomized to yoga and no-yoga cohorts (1:1). Twice-weekly yoga interventions were offered throughout the 6- to 9-week courses of RT. Comparisons of standardized assessments were performed between the 2 cohorts for the primary endpoint of fatigue and the secondary endpoints of erectile dysfunction, urinary incontinence, and QOL before, during, and after RT...
August 1, 2017: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/28716947/thermodynamic-constraint-on-the-depth-of-the-global-tropospheric-circulation
#6
David W J Thompson, Sandrine Bony, Ying Li
The troposphere is the region of the atmosphere characterized by low static stability, vigorous diabatic mixing, and widespread condensational heating in clouds. Previous research has argued that in the tropics, the upper bound on tropospheric mixing and clouds is constrained by the rapid decrease with height of the saturation water vapor pressure and hence radiative cooling by water vapor in clear-sky regions. Here the authors contend that the same basic physics play a key role in constraining the vertical structure of tropospheric mixing, tropopause temperature, and cloud-top temperature throughout the globe...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28716113/whole-metagenome-profiles-of-particulates-collected-from-the-international-space-station
#7
Nicholas A Be, Aram Avila-Herrera, Jonathan E Allen, Nitin Singh, Aleksandra Checinska Sielaff, Crystal Jaing, Kasthuri Venkateswaran
BACKGROUND: The built environment of the International Space Station (ISS) is a highly specialized space in terms of both physical characteristics and habitation requirements. It is unique with respect to conditions of microgravity, exposure to space radiation, and increased carbon dioxide concentrations. Additionally, astronauts inhabit a large proportion of this environment. The microbial composition of ISS particulates has been reported; however, its functional genomics, which are pertinent due to potential impact of its constituents on human health and operational mission success, are not yet characterized...
July 17, 2017: Microbiome
https://www.readbyqxmd.com/read/28713116/therapeutic-evaluation-of-cervical-dysfunction-in-patients-with-myofascial-pain-dysfunction-syndrome-a-prospective-study
#8
B Smriti Jagdhari, Motwani Mukta, A Golhar Saket, Anil V Golhar
AIM: The aim of this study was to find out the therapeutic correlation between cervical dysfunction and myofascial pain dysfunction syndrome (MPDS). MATERIALS AND METHODS: The study included 46 patients out of which 23 had MPDS with cervical pain (group I), and 23 patients had only MPDS (group II). Detailed history and examination of the patients were carried out, and the factors taken into consideration were pain and tenderness of muscles of mastication and neck muscles, maximum comfortable mouth opening, and cervical range of motion...
July 1, 2017: Journal of Contemporary Dental Practice
https://www.readbyqxmd.com/read/28712282/deformable-image-registration-in-radiation-therapy
#9
REVIEW
Seungjong Oh, Siyong Kim
The number of imaging data sets has significantly increased during radiation treatment after introducing a diverse range of advanced techniques into the field of radiation oncology. As a consequence, there have been many studies proposing meaningful applications of imaging data set use. These applications commonly require a method to align the data sets at a reference. Deformable image registration (DIR) is a process which satisfies this requirement by locally registering image data sets into a reference image set...
June 2017: Radiation Oncology Journal
https://www.readbyqxmd.com/read/28711839/variance-reduction-technique-in-a-beta-radiation-beam-using-an-extrapolation-chamber
#10
Ivón Oramas Polo, William Souza Santos, Patrícia de Lara Antonio, Linda V E Caldas
This paper aims to show how the variance reduction technique "Geometry splitting/Russian roulette" improves the statistical error and reduces uncertainties in the determination of the absorbed dose rate in tissue using an extrapolation chamber for beta radiation. The results show that the use of this technique can increase the number of events in the chamber cavity leading to a closer approximation of simulation result with the physical problem. There was a good agreement among the experimental measurements, the certificate of manufacture and the simulation results of the absorbed dose rate values and uncertainties...
June 20, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28711774/a-rotating-slit-collimator-based-gamma-radiation-mapper
#11
Jonas M C Nilsson, Robert R Finck, Christopher L Rääf
For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built...
July 13, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28711200/dual-energy-computed-tomography-physical-principles-approaches-to-scanning-usage-and-implementation-part-2
#12
REVIEW
Reza Forghani, Bruno De Man, Rajiv Gupta
There are increasing applications and use of spectral computed tomography or dual-energy computed tomography (DECT) in neuroradiology and head and neck imaging in routine clinical practice. Part 1 of this 2-part review covered fundamental physical principles underlying DECT scanning and the different approaches for scanning. Part 2 focuses on important and practical considerations for implementing and using DECT in clinical practice, including a review of different images and reconstructions produced by these scanners and important and practical issues, ranging from image quality and radiation dose to workflow-related aspects of DECT scanning, that routinely come up during operationalization of DECT...
August 2017: Neuroimaging Clinics of North America
https://www.readbyqxmd.com/read/28709028/in-vitro-investigation-of-the-dose-rate-effect-on-the-biological-effectiveness-of-megavoltage-x-ray-radiation-doses
#13
Sianne Oktaria, Michael L F Lerch, Anatoly B Rosenfeld, Moeava Tehei, Stéphanie Corde
Radiation therapy is rapidly evolving toward the delivery of higher dose rates to improve cancer treatment. In vitro experiments were performed to investigate the response of 9L and MCF-7 cancer cell lines, exposed to 10MV X-ray radiations. Up to 8Gy was delivered at a dose-rate of 50cGy/min compared to 5Gy/min. The data obtained emphasizes the importance of taking into account not only the physical, but also the radiobiological parameters, when planning a particular cancer treatment.
July 6, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28707369/psychological-stress-affects-the-severity-of-radiation-induced-acute-skin-reactions-in-breast-cancer-patients
#14
A E Sutherland, N C Bennett, P M Herst
Psychological stress exacerbates many pathological conditions including inflammatory skin conditions. The effect of psychological stress on acute radiation-induced skin reactions has not been documented before. Here, we aimed to explore if psychological stress could aggravate skin reaction severity in breast cancer patients. We conducted a secondary analysis of patient data obtained during a randomised, controlled clinical trial for acute radiation-induced skin reaction severity in 78 breast cancer patients...
July 13, 2017: European Journal of Cancer Care
https://www.readbyqxmd.com/read/28706863/non-functional-tricuspid-valve-disease
#15
REVIEW
Dale S Adler
Only 75% of severe tricuspid regurgitation is classified as functional, or related primarily to pulmonary hypertension, right ventricular dysfunction, or a combination of both. Non-functional tricuspid regurgitation occurs when there is damage to the tricuspid leaflets, chordae, papillary muscles, or annulus, independent of right ventricular dysfunction or pulmonary hypertension. The entities that cause non-functional tricuspid regurgitation include rheumatic and myxomatous disease, acquired and genetic connective tissue disorders, endocarditis, sarcoid, pacing, RV biopsy, blunt trauma, radiation, carcinoid, ergot alkaloids, dopamine agonists, fenfluramine, cardiac tumors, atrial fibrillation, and congenital malformations...
May 2017: Annals of Cardiothoracic Surgery
https://www.readbyqxmd.com/read/28703944/low-dimensional-organic-inorganic-halide-perovskite-structure-properties-and-applications
#16
Ravi K Misra, Bat-El Cohen, Lior Iagher, Lioz Etgar
Three-dimensional (3D) perovskite has attracted a lot of attention due to its success in photovoltaic (PV) solar cells. However, one the major crucial issues lies in its stability, which has limited its commercialization. An important property of organic-inorganic perovskite is the possibility of forming a layered material using long organic cations that do not fit into the octahedral cage. The long organic cation acts as a "barrier" that "caps" the 3D perovskite forming the layered material. Controlling the number of perovskite layers could provide a confined structure with different chemical and physical properties than 3D perovskite has...
July 13, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28702770/oncologic-outcomes-after-treatment-for-mri-occult-breast-cancer-pt0n
#17
Damian P McCartan, Emily C Zabor, Monica Morrow, Kimberly J Van Zee, Mahmoud B El-Tamer
BACKGROUND: Studies assessing outcomes in occult breast cancer have often included women treated before the routine use of magnetic resonance imaging (MRI). This study examined outcomes for patients presenting with axillary adenopathy and no primary breast tumor detectable by MRI or other imaging methods. METHODS: All patients with axillary nodal metastases consistent with breast carcinoma and no breast primary tumor detectable by physical exam, mammography, or MRI treated between 1 January 1996 and 30 June 2011 were identified from an institutional database...
July 12, 2017: Annals of Surgical Oncology
https://www.readbyqxmd.com/read/28701660/precision-in-wedge-off-axis-using-independent-dose-verification
#18
Hiroyuki Shimizu, Masanobu Itano, Takeshi Yamazaki, Ryo Takahashi, Tatsuya Kamima, Mikiko Yamashita, Hiromi Baba, Satoru Ishibashi, Yoshihiro Higuchi, Toshijiro Yamamoto, Yasuharu Sugawara, Aya Sato, Shiro Nishiyama, Satoshi Miyaoka, Daisuke Kawai, Hidenobu Tachibana
It is essential for quality assurance to verify the safety of each individual patient's plan in radiation therapy. The tolerance level for independent verification of monitor unit calculations for non-IMRT clinical radiotherapy has been shown in the AAPM TG114. Thus, we investigated the precision of independent MU (dose) verification considering a wedge off-axis calculation and we conducted a study at twelve institutes for independent verification with the wedge off-axis calculation. The results obtained with the wedge off-axis calculation showed better agreement with the treatment planning system calculation results than those without the former calculation in a phantom study and in the patient retrospective study...
2017: Japanese Journal of Medical Physics
https://www.readbyqxmd.com/read/28700348/mechanisms-of-phosphenes-in-irradiated-patients
#19
REVIEW
Thibaud Mathis, Stephane Vignot, Cecila Leal, Jean-Pierre Caujolle, Celia Maschi, Martine Mauget-Faÿsse, Laurent Kodjikian, Stéphanie Baillif, Joel Herault, Juliette Thariat
Anomalous visual perceptions have been reported in various diseases of the retina and visual pathways or can be experienced under specific conditions in healthy individuals. Phosphenes are perceptions of light in the absence of ambient light, occurring independently of the physiological and classical photonic stimulation of the retina. They are a frequent symptom in patients irradiated in the region of the central nervous system (CNS), head and neck and the eyes. Phosphenes have historically been attributed to complex physical phenomena such as Cherenkov radiation...
June 28, 2017: Oncotarget
https://www.readbyqxmd.com/read/28699418/evaluation-of-deformable-image-registration-based-contour-propagation-from-planning-ct-to-cone-beam-ct
#20
Andrew J Woerner, Mehee Choi, Matthew M Harkenrider, John C Roeske, Murat Surucu
PURPOSE: We evaluated the performance of organ contour propagation from a planning computed tomography to cone-beam computed tomography with deformable image registration by comparing contours to manual contouring. MATERIALS AND METHODS: Sixteen patients were retrospectively identified based on showing considerable physical change throughout the course of treatment. Multiple organs in the 3 regions (head and neck, prostate, and pancreas) were evaluated. A cone-beam computed tomography from the end of treatment was registered to the planning computed tomography using rigid registration, followed by deformable image registration...
January 1, 2017: Technology in Cancer Research & Treatment
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