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https://www.readbyqxmd.com/read/28545556/finer-leaf-resolution-and-steeper-beam-edges-using-a-virtual-isocentre-in-concurrence-to-ptv-shaped-collimators-in-standard-distance-a-planning-study
#1
Klaus Bratengeier, Barbara Herzog, Sonja Wegener, Kostyantyn Holubyev
PURPOSE: Investigation of a reduced source to target distance to improve organ at risk sparing during stereotactic irradiation (STX). METHODS: The authors present a planning study with perfectly target-volume adapted collimator compared with multi-leaf collimator (MLC) at reduced source to virtual isocentre distance (SVID) in contrast to normal source to isocentre distance (SID) for stereotactic applications. The role of MLC leaf width and 20-80% penumbra was examined concerning the healthy tissue sparing...
May 25, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28541774/meaning-making-after-partner-suicide-a-narrative-exploration-using-the-meaning-of-loss-codebook
#2
Tyler R Pritchard, Jennifer L Buckle
This study explored meaning-making in the narratives of survivors of partner suicide. The 117 posts of 50 users of a public online grief support forum were analyzed using the Meaning of Loss Codebook (Gillies, Neimeyer, & Milman, 2014 ). There was evidence of substantial psychological distress and an ongoing struggle to make meaning of the death, in addition to focusing on memories, longing for the deceased, and efforts to actively cope with the loss. Given the importance of meaning-making in the adjustment to loss, and through the application of the MLC, these findings deepen the understanding of this component of grief...
May 25, 2017: Death Studies
https://www.readbyqxmd.com/read/28535917/sensitivity-evaluation-of-two-commercial-dosimeters-in-detecting-helical-tomotherapy-treatment-delivery-errors
#3
Shrikant Deshpande, Mark Geurts, Philip Vial, Peter Metcalfe, Lois Holloway
PURPOSE: To assess the sensitivity of two commercial dosimetry systems in detecting Helical TomoTherapy (HT) delivery errors. METHOD: Two commercial dosimeters i) MatriXX(Evolution) and ii) ArcCHECK® were considered. Ten retrospective nasopharynx HT patients were analysed. For each patient, error plans were created by independently introducing systematic offsets in: a) Jaw width error ±1, ±1.5 and ±2mm, b) Couch speed error ±2%, ±2.5, ±3% and ±4%, and c) MLC Leaf Open Time (MLCLOT) errors (3 separate MLC errors: either leaf 32 open or leaf 42 remains open during delivery, and 4% random reductions in MLCLOT)...
May 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28529252/consideration-of-dose-error-in-dynamic-mlc-imrt-using-mlc-speed-control-with-dose-rate-change
#4
Hideki Kojima, Makoto Takigami, Tomohiro Asano, Yasuhiro Hatanaka, Kazuhiro Aizawa, Masayori Ishikawa
In dynamic multi-leaf collimator (MLC) intensity-modulated radiotherapy (IMRT), the accuracy of delivered dose is influenced by the positional accuracy of the moving MLC. In order to assess the accuracy of the delivered dose during dynamic MLC IMRT, the delivered dose error in dynamic MLC IMRT using the MLC speed control with dose rate change was investigated. Sweeping gap sequence irradiation was performed with constant MLC leaf speed at 0.6 to 5 cm/s or changed MLC speed (4 steps). The positional accuracy of the moving MLC was evaluated from the trajectory log file...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28529250/impact-of-jaw-position-accuracy-on-dose-variation-in-volumetric-modulated-arc-therapy-using-jaw-tracking
#5
Fumiyasu Matsubayashi, Yuki Koizumi, Ryo Takahashi, Minoru Yoshioka, Tomoharu Sato
The technique of jaw tracking can be used in volumetric modulated arc therapy (VMAT) and intensity modulated radiation therapy (IMRT). In this technique, jaw tracks apertures of the multi leaf collimator (MLC) during irradiation. It is reported that dose variation is occurred by the changing accuracy of MLC position in VMAT and IMRT. Though jaw moves dynamically in the irradiation by using this technique, the influence of the jaw position accuracy on dose variation is not examined. The purpose of this study is to verify the influence of jaw position accuracy on dose variation in VMAT using jaw tracking...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28517613/a-quantitative-method-to-the-analysis-of-mlc-leaf-position-and-speed-based-on-epid-and-ebt3-film-for-dynamic-imrt-treatment-with-different-types-of-mlc
#6
Yinghui Li, Lixin Chen, Jinhan Zhu, Bin Wang, Xiaowei Liu
A quantitative method based on the electronic portal imaging system (EPID) and film was developed for MLC position and speed testing; this method was used for three MLC types (Millennium, MLCi, and Agility MLC). To determine the leaf position, a picket fence designed by the dynamic (DMLC) model was used. The full-width half-maximum (FWHM) values of each gap measured by EPID and EBT3 were converted to the gap width using the FWHM versus nominal gap width relationship. The algorithm developed for the picket fence analysis was able to quantify the gap width, the distance between gaps, and each individual leaf position...
May 18, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28510572/1-2-million-kids-and-counting-mobile-science-laboratories-drive-student-interest-in-stem
#7
Amanda L Jones, Mary K Stapleton
In today's increasingly technological society, a workforce proficient in science, technology, engineering, and mathematics (STEM) skills is essential. Research has shown that active engagement by K-12 students in hands-on science activities that use authentic science tools promotes student learning and retention. Mobile laboratory programs provide this type of learning in schools and communities across the United States and internationally. Many programs are members of the Mobile Lab Coalition (MLC), a nonprofit organization of mobile and other laboratory-based education programs built on scientist and educator collaborations...
May 2017: PLoS Biology
https://www.readbyqxmd.com/read/28509344/cgmp-signalling-inhibits-platelet-shape-change-through-regulation-of-the-rhoa-rho-kinase-mlc-phosphatase-signalling-pathway
#8
Ahmed Aburima, Kochar Walladbegi, Jonathan D Wake, Khalid M Naseem
BACKGROUND: Platelet shape change, spreading and thrombus stability requires activation of the actin cytoskeleton contractile machinery. The mechanisms controlling actin assembly to prevent unwanted platelet activation are unclear. OBJECTIVES: We examined the effects of nitric oxide on the signalling pathways regulating platelet actin-myosin activation. RESULTS: S-nitrosoglutathione (GSNO) inhibited thrombin-induced platelet shape change and myosin phosphorylation of myosin light chain (MLC)...
May 16, 2017: Journal of Thrombosis and Haemostasis: JTH
https://www.readbyqxmd.com/read/28500783/on-mixed-electron-photon-radiation-therapy-optimisation-using-the-column-generation-approach
#9
Marc-André Renaud, Monica Serban, Jan Seuntjens
PURPOSE: Despite considerable increase in the number of degrees of freedom handled by recent radiotherapy optimisation algorithms, treatments are still typically delivered using a single modality. Column generation is an iterative method for solving large optimisation problems. It is well suited for mixed-modality (e.g., photon-electron) optimisation as the aperture shaping and modality selection problem can be solved rapidly, and the performance of the algorithm scales favourably with increasing degrees of freedom...
May 13, 2017: Medical Physics
https://www.readbyqxmd.com/read/28488585/eets-reduces-lps-induced-hyperpermeability-by-targeting-grp78-mediated-src-activation-and-subsequent-rho-rock-signaling-pathway
#10
Ruolan Dong, Danli Hu, Yan Yang, Zhihui Chen, Menglu Fu, Dao Wen Wang, Xizhen Xu, Ling Tu
Integrity of endothelial barrier is a determinant of the prognosis in the acute lung injury caused by sepsis. The epoxyeicosatrienoic acids (EETs), metabolites of arachidonic acid, exhibit protective effects in various pathogenic states, however, whether EETs play a role in endothelial barrier enhancement and the involved mechanisms remain to be investigated. Here, we show that increased EETs level by endothelial specific cytochrome P450 epoxygenase 2J2 over-expression and soluble epoxide hydrolase (sEH) inhibitor TPPU reduced lipopolysaccharide-induced endothelial hyper-permeability in vivo, accompanied by improved survival of septic mice...
April 21, 2017: Oncotarget
https://www.readbyqxmd.com/read/28487237/cytokines-affecting-cd4-t-regulatory-cells-in-transplant-tolerance-ii-interferon-gamma-ifn-%C3%AE-promotes-survival-of-alloantigen-specific-cd4-t-regulatory-cells
#11
Masaru Nomura, Suzanne J Hodgkinson, Giang T Tran, Nirupama D Verma, Catherine Robinson, Karren M Plain, Rochelle Boyd, Bruce M Hall
CD4(+)T cells that transfer alloantigen-specific transplant tolerance are short lived in culture unless stimulated with specific-donor alloantigen and lymphocyte derived cytokines. Here, we examined if IFN-γ maintained survival of tolerance transferring CD4(+)T cells. Alloantigen-specific transplant tolerance was induced in DA rats with heterotopic adult PVG heart allografts by a short course of immunosuppression and these grafts functioned for >100days with no further immunosuppression. In previous studies, we found the CD4(+)T cells from tolerant rats that transfer tolerance to an irradiated DA host grafted with a PVG heart, lose their tolerance transferring ability after 3days of culture, either with or without donor alloantigen, and effect rejection of specific-donor grafts...
May 6, 2017: Transplant Immunology
https://www.readbyqxmd.com/read/28484504/effect-of-qskl-on-mapk-and-rhoa-pathways-in-a-rat-model-of-heart-failure
#12
Kai Xia, Qiyan Wang, Chun Li, Zifan Zeng, Yong Wang, Wei Wang
Qishenkeli (QSKL) is one of the Chinese medicine formulae for treating heart failure and has been shown to have an antifibrotic effect. However, the mechanism of its therapeutic effects remains unclear. In this study, we aimed to explore whether QSKL could exert an antifibrotic effect by attenuating ras homolog family member A (RhoA) and mitogen activated protein kinase (MAPK) pathways. Rats were randomly divided into sham group, model group, QSKL group, and positive control group. Heart failure was induced by ligation of the left ventricle anterior descending artery...
2017: Evidence-based Complementary and Alternative Medicine: ECAM
https://www.readbyqxmd.com/read/28484126/mechanisms-underlying-the-pathogenesis-of-hyper-contractility-of-bronchial-smooth-muscle-in-allergic-asthma
#13
Hiroyasu Sakai, Wataru Suto, Yuki Kai, Yoshihiko Chiba
Airway hyperresponsiveness (AHR) and inflammation are key pathophysiological features of asthma. Enhanced contraction of bronchial smooth muscle (BSM) is one of the causes of the AHR. It is thus important for development of asthma therapy to understand the change in the contractile signaling of airway smooth muscle cells associated with the AHR. In addition to the Ca(2+)-mediated phosphorylation of myosin light chain (MLC), contractile agonists also enhance MLC phosphorylation level, Ca(2+)-independently, by inactivating MLC phosphatase (MLCP), called Ca(2+) sensitization of contraction, in smooth muscle cells including airways...
2017: Journal of Smooth Muscle Research, Nihon Heikatsukin Gakkai Kikanshi
https://www.readbyqxmd.com/read/28474504/mouse-nidovirus-ldv-infection-alleviates-graft-versus-host-disease-and-induces-type-i-ifn-dependent-inhibition-of-dendritic-cells-and-allo-responsive-t-cells
#14
Mélanie Gaignage, Reece G Marillier, Catherine Uyttenhove, Nicolas Dauguet, Anubha Saxena, Bernard Ryffel, Thomas Michiels, Jean-Paul Coutelier, Jacques Van Snick
INTRODUCTION: Viruses have developed multiple mechanisms to alter immune reactions. In 1969, it was reported that lactate dehydrogenase-elevating virus (LDV), a single stranded positive sense mouse nidovirus, delays skin allograft rejection and inhibits spleen alterations in graft versus host disease (GVHD). As the underlying mechanisms have remained unresolved and given the need for new therapies of this disease, we reassessed the effects of the virus on GVHD and tried to uncover its mode of action...
June 2017: Immunity, Inflammation and Disease
https://www.readbyqxmd.com/read/28470819/tuning-of-acurosxb-source-size-setting-for-small-intracranial-targets
#15
Stephen J Gardner, Siming Lu, Chang Liu, Ning Wen, Indrin J Chetty
This study details a method to evaluate the source size selection for small field intracranial stereotactic radiosurgery (SRS) deliveries in Eclipse treatment planning system (TPS) for AcurosXB dose calculation algorithm. Our method uses end-to-end dosimetric data to evaluate a total of five source size selections (0.50 mm, 0.75 mm, 1.00 mm, 1.25 mm, and 1.50 mm). The dosimetric leaf gap (DLG) was varied in this analysis (three DLG values were tested for each scenario). We also tested two MLC leaf designs (standard and high-definition MLC) and two delivery types for intracranial SRS (volumetric modulated arc therapy [VMAT] and dynamic conformal arc [DCA])...
May 4, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28457723/dosimetric-effect-of-multileaf-collimator-leaf-width-on-volumetric-modulated-arc-stereotactic-radiotherapy-for-spine-tumors
#16
Ahmad Amoush, Huang Long, Laxmi Subedi, Peng Qi, Toufik Djemil, Ping Xia
This work aimed to study the dosimetric effect of multileaf collimator (MLC) leaf widths in treatment plans for patients receiving volumetric modulated arc therapy (VMAT) for spine stereotactic body radiation therapy (SBRT). Thirteen patients treated with spine SBRT were retrospectively selected for this study. The patients were treated following the protocol of the Radiation Therapy Oncology Group 0631 (RTOG 0631) for spine metastasis. The prescription dose was 16 Gy in 1 fraction to 90% of the target volume (V16 > 90%)...
April 28, 2017: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
https://www.readbyqxmd.com/read/28453519/homozygous-arhgef2-mutation-causes-intellectual-disability-and-midbrain-hindbrain-malformation
#17
Ethiraj Ravindran, Hao Hu, Scott A Yuzwa, Luis R Hernandez-Miranda, Nadine Kraemer, Olaf Ninnemann, Luciana Musante, Eugen Boltshauser, Detlev Schindler, Angela Hübner, Hans-Christian Reinecker, Hans-Hilger Ropers, Carmen Birchmeier, Freda D Miller, Thomas F Wienker, Christoph Hübner, Angela M Kaindl
Mid-hindbrain malformations can occur during embryogenesis through a disturbance of transient and localized gene expression patterns within these distinct brain structures. Rho guanine nucleotide exchange factor (ARHGEF) family members are key for controlling the spatiotemporal activation of Rho GTPase, to modulate cytoskeleton dynamics, cell division, and cell migration. We identified, by means of whole exome sequencing, a homozygous frameshift mutation in the ARHGEF2 as a cause of intellectual disability, a midbrain-hindbrain malformation, and mild microcephaly in a consanguineous pedigree of Kurdish-Turkish descent...
April 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28425084/independent-dose-verification-for-brain-stereotactic-radiotherapy-using-different-add-on-micro-multi-leaf-collimators
#18
Shiro Nishiyama, Satoru Ishibashi, Ryo Takahashi, Hidenobu Tachibana
An add-on micro multi-leaf collimator (mMLC) is used for stereotactic radiosurgery (SRS) and brain stereotactic radiotherapy (SRT), in which rotational radiotherapy may make more complex and time-consuming. We performed a retrospective study of an independent dose calculation verification for brain SRS and SRT in two institutions to show the accuracy of the verification system and propose a tolerance value for the verification. Several comparisons of static plans and patients' plans were conducted using a phantom measurement, and patients' plans using the patients' own computed tomography image...
April 19, 2017: Radiological Physics and Technology
https://www.readbyqxmd.com/read/28422401/mlc-based-penumbra-softener-of-edw-borders-to-reduce-junction-inhomogeneities
#19
Stanislaw Szpala, Kirpal Kohli
Junctions of fields are known to be susceptible to developing cold or hot spots in the presence of even small geometrical misalignments. Reduction of these dose inhomogeneities can be accomplished through decreasing the dose gradients in the penumbra, but currently it cannot be done for enhanced dynamic wedges (EDW). An MLC-based penumbra softener was developed in the developer mode of TrueBeam linacs to reduce dose gradients across the side border of EDWs. The movement of each leaf was individually synchronized with the movement of the dynamic Y jaw to soften the penumbra in the same manner along the entire field border, in spite of the presence of the dose gradient of the EDW...
April 19, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28419702/evaluation-of-the-truebeam-machine-performance-check-mpc-mechanical-and-collimation-checks
#20
Michael P Barnes, Peter B Greer
Machine performance check (MPC) is an automated and integrated image-based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the performance of the MPC geometric tests relevant to beam collimation (MLC and jaws) and mechanical systems (gantry and collimator). Evaluation was performed by comparing MPC to QA tests performed routinely in the department over a 4-month period. The MPC MLC tests were compared to an in-house analysis of the Picket Fence test...
April 17, 2017: Journal of Applied Clinical Medical Physics
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