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Colocutaneous Fistula Following Pediatric Bivad Implantation, A Rare but Serious Complication. J Heart Lung Transplant 2023. [DOI: 10.1016/j.healun.2023.02.1246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
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2
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A Model to Evaluate Effect of Patient-Pump Mismatch on Thrombosis in a Pediatric Pulsatile Ventricular Assist Device. J Heart Lung Transplant 2021. [DOI: 10.1016/j.healun.2021.01.1233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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3
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Dynamics of ERK regulation in the processive limit. J Math Biol 2021; 82:32. [PMID: 33694015 DOI: 10.1007/s00285-021-01574-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 09/01/2020] [Accepted: 02/13/2021] [Indexed: 10/21/2022]
Abstract
We consider a model of extracellular signal-regulated kinase regulation by dual-site phosphorylation and dephosphorylation, which exhibits bistability and oscillations, but loses these properties in the limit in which the mechanisms underlying phosphorylation and dephosphorylation become processive. Our results suggest that anywhere along the way to becoming processive, the model remains bistable and oscillatory. More precisely, in simplified versions of the model, precursors to bistability and oscillations (specifically, multistationarity and Hopf bifurcations, respectively) exist at all "processivity levels". Finally, we investigate whether bistability and oscillations can exist together.
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Abstract
In systems and synthetic biology, much research has focused on the behavior and design of single pathways, while, more recently, experimental efforts have focused on how cross-talk (coupling two or more pathways) or inhibiting molecular function (isolating one part of the pathway) affects systems-level behavior. However, the theory for tackling these larger systems in general has lagged behind. Here, we analyze how joining networks (e.g., cross-talk) or decomposing networks (e.g., inhibition or knock-outs) affects three properties that reaction networks may possess-identifiability (recoverability of parameter values from data), steady-state invariants (relationships among species concentrations at steady state, used in model selection), and multistationarity (capacity for multiple steady states, which correspond to multiple cell decisions). Specifically, we prove results that clarify, for a network obtained by joining two smaller networks, how properties of the smaller networks can be inferred from or can imply similar properties of the original network. Our proofs use techniques from computational algebraic geometry, including elimination theory and differential algebra.
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Abstract
A convex code is a binary code generated by the pattern of intersections of a collection of open convex sets in some Euclidean space. Convex codes are relevant to neuroscience as they arise from the activity of neurons that have convex receptive fields. In this paper, we use algebraic methods to determine if a code is convex. Specifically, we use the neural ideal of a code, which is a generalization of the Stanley-Reisner ideal. Using the neural ideal together with its standard generating set, the canonical form, we provide algebraic signatures of certain families of codes that are non-convex. We connect these signatures to the precise conditions on the arrangement of sets that prevent the codes from being convex. Finally, we also provide algebraic signatures for some families of codes that are convex, including the class of intersection-complete codes. These results allow us to detect convexity and non-convexity in a variety of situations, and point to some interesting open questions.
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Emergence of Oscillations in a Mixed-Mechanism Phosphorylation System. Bull Math Biol 2019; 81:1829-1852. [DOI: 10.1007/s11538-019-00580-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Accepted: 02/08/2019] [Indexed: 10/27/2022]
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7
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An all-encompassing global convergence result for processive multisite phosphorylation systems. Math Biosci 2017; 291:1-9. [DOI: 10.1016/j.mbs.2017.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 04/13/2017] [Accepted: 05/17/2017] [Indexed: 10/19/2022]
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8
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SU-F-T-644: Reproducibility of Target Position Using Moderate Voluntary Breath- Hold During Liver Stereotactic Ablative Radiotherapy. Med Phys 2016. [DOI: 10.1118/1.4956829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-F-T-76: Total Skin Electron Therapy: An-End-To-End Examination of the Absolute Dosimetry with a Rando Phantom. Med Phys 2016. [DOI: 10.1118/1.4956212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-E-T-92: Achieving Desirable Lung Doses in Total Body Irradiation Based On in Vivo Dosimetry and Custom Tissue Compensation. Med Phys 2015. [DOI: 10.1118/1.4924453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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11
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TU-G-BRD-04: A Round Robin Dosimetry Intercomparison of Gamma Stereotactic Radiosurgery Calibration Protocols. Med Phys 2015. [DOI: 10.1118/1.4925739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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12
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A Global Convergence Result for Processive Multisite Phosphorylation Systems. Bull Math Biol 2014; 77:126-55. [DOI: 10.1007/s11538-014-0054-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 12/10/2014] [Indexed: 11/24/2022]
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13
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Comparative Healthcare Systems Program: Inspiring changes in public
health through first-hand experiences of the Quebec and Taiwanese health
systems. Ann Glob Health 2014. [DOI: 10.1016/j.aogh.2014.08.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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SU-E-T-282: Remove Field-Size Limitation Using the Combination of Collimator Rotation and Jaw Tracking with MLC Aperture. Med Phys 2014. [DOI: 10.1118/1.4888613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-E-T-569: Evaluation of VMAT Plans Generated with HD120 and Millennium 120 MLC Between Two Matched Linacs. Med Phys 2014. [DOI: 10.1118/1.4888904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-E-T-188: Evaluation of a 3D Patient Relevant Dose QA Tool: Multiple Institutional Studies. Med Phys 2012; 39:3746. [PMID: 28517837 DOI: 10.1118/1.4735247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE To evaluate 3DVHTM as a patient dose-verification and analysis tool through multiple institutional studies. Virtual patient doses were measured and compared among different vendors' treatment planning systems (TPS) and delivered by different vendors' LINACS so that we better understand the uncertainty of entire process within a patient undergone radiotherapy. METHODS One head-and-neck (H&N) and one lung patient were selected in this study. The DICOM images/RT structures along with clinical protocols including prescription doses (59.4Gy for H&N and 70.2Gy for lung) and normal‐tissues tolerances were distributed to six institutions. Based on the same criteria, each institution generated their IMRT plans for the patients. Four different TPS and six different LINACS were used. The conventional per‐beam IMRT QA using MapCHECK was performed by all participants. All the measured and calculated data were sent back to one institution for 3DVH analysis. Through the use of planned-dose-perturbation (PDP)TM algorithm (Sun Nuclear Corp.), the 'actual-DVHs' were generated and then compared to the 'reference-DVHs' from plans. Their differences represented errors induced from the combination of TPS dose-calculation algorithm and beam-delivery systems. RESULTS All plans in the study have met the clinical criteria. The 3D matching rates for 3%global/3mm (DD/DTA) ranged from 95.8-99.9% for H&N and 93.5-100% for lung. The dose-difference-histogram for PTV had a mean of 0.67% [0-2%] for H&N cases and 1% [0.6-2.8%] for lung cases. The QA tool was able to spot the doses outside 3%/3mm criteria for critical structures much easier than conventional planar QA methods. In addition, the hot/cold spots at the boundaries of collimators are attributed to the uncertainty of collimator-positioning greater than 1-mm. CONCLUSIONS The analysis of IMRT plans in this study has shown that 3DVH is a vital QA tool for assessing clinically relevant doses as well as diagnosing potential systematic errors from both TPS and delivery systems.
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Generalizable Class Solutions for Treatment Planning of Spinal Stereotactic Body Radiation Therapy Cases. Int J Radiat Oncol Biol Phys 2011. [DOI: 10.1016/j.ijrobp.2011.06.1523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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18
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SU-E-T-244: Should Treatment Time Be Included in Assessing the Quality of a Gamma Plan? Med Phys 2011. [DOI: 10.1118/1.3612195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-GG-T-516: Investigation of Large Discrepancies in Dose-Rates of Gamma-Knife Units at Various Institutions. Med Phys 2010. [DOI: 10.1118/1.3468912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-GG-J-74: Congruence of Cone-Beam CT Image Center with the Radiation Isocenter of a Linear Accelerator. Med Phys 2010. [DOI: 10.1118/1.3468298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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21
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SU-GG-T-552: Commissioning an Anthropomorphic Spine and Lung Phantom for Remote Quality Assurance of Spinal Radiosurgery. Med Phys 2010. [DOI: 10.1118/1.3468950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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22
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Apparatus-dependent Differences in Spine Stereotactic Body Radiosurgery (SBRT) Dosimetry. Int J Radiat Oncol Biol Phys 2009. [DOI: 10.1016/j.ijrobp.2009.07.1545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Comparison of pattern detection methods in microarray time series of the segmentation clock. PLoS One 2008; 3:e2856. [PMID: 18682743 PMCID: PMC2481401 DOI: 10.1371/journal.pone.0002856] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 04/26/2008] [Indexed: 02/02/2023] Open
Abstract
While genome-wide gene expression data are generated at an increasing rate, the repertoire of approaches for pattern discovery in these data is still limited. Identifying subtle patterns of interest in large amounts of data (tens of thousands of profiles) associated with a certain level of noise remains a challenge. A microarray time series was recently generated to study the transcriptional program of the mouse segmentation clock, a biological oscillator associated with the periodic formation of the segments of the body axis. A method related to Fourier analysis, the Lomb-Scargle periodogram, was used to detect periodic profiles in the dataset, leading to the identification of a novel set of cyclic genes associated with the segmentation clock. Here, we applied to the same microarray time series dataset four distinct mathematical methods to identify significant patterns in gene expression profiles. These methods are called: Phase consistency, Address reduction, Cyclohedron test and Stable persistence, and are based on different conceptual frameworks that are either hypothesis- or data-driven. Some of the methods, unlike Fourier transforms, are not dependent on the assumption of periodicity of the pattern of interest. Remarkably, these methods identified blindly the expression profiles of known cyclic genes as the most significant patterns in the dataset. Many candidate genes predicted by more than one approach appeared to be true positive cyclic genes and will be of particular interest for future research. In addition, these methods predicted novel candidate cyclic genes that were consistent with previous biological knowledge and experimental validation in mouse embryos. Our results demonstrate the utility of these novel pattern detection strategies, notably for detection of periodic profiles, and suggest that combining several distinct mathematical approaches to analyze microarray datasets is a valuable strategy for identifying genes that exhibit novel, interesting transcriptional patterns.
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SU-GG-T-448: Online Isocenter Corrections Based On Image Registration and Automatic Target Finding in SRS/SRT Cranial Treatment with the Bite-Block Frame System. Med Phys 2008. [DOI: 10.1118/1.2962196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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25
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Dose Distribution Comparison for the IGRT Treatment Using CyberKnife Versus LINAC IMRT Stereotactic Body Radiotherapy. Int J Radiat Oncol Biol Phys 2007. [DOI: 10.1016/j.ijrobp.2007.07.2056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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26
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The cyclohedron test for finding periodic genes in time course expression studies. Stat Appl Genet Mol Biol 2007; 6:Article 21. [PMID: 17764440 DOI: 10.2202/1544-6115.1286] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The problem of finding periodically expressed genes from time course microarray experiments is at the center of numerous efforts to identify the molecular components of biological clocks. We present a new approach to this problem based on the cyclohedron test, which is a rank test inspired by recent advances in algebraic combinatorics. The test has the advantage of being robust to measurement errors, and can be used to ascertain the significance of top-ranked genes. We apply the test to recently published measurements of gene expression during mouse somitogenesis and find 32 genes that collectively are significant. Among these are previously identified periodic genes involved in the Notch/FGF and Wnt signaling pathways, as well as novel candidate genes that may play a role in regulating the segmentation clock. These results confirm that there are an abundance of exceptionally periodic genes expressed during somitogenesis. The emphasis of this paper is on the statistics and combinatorics that underlie the cyclohedron test and its implementation within a multiple testing framework.
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SU-FF-J-40: Image-Guided Body Stereotactic Radiotherapy Using Cone-Beam Computer Tomography for Treatment of Spinal Tumors. Med Phys 2007. [DOI: 10.1118/1.2760545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-FF-T-164: Dose Distribution Comparison for the Treatment of Lung and Spinal Metastases Using CyberKnife Versus IMRT Stereotactic Body Radiotherapy. Med Phys 2007. [DOI: 10.1118/1.2760823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-FF-T-45: A Procedure for Correcting the Effect of Detector Properties On Measured Profiles of Small Field MV X-Ray Beams. Med Phys 2006. [DOI: 10.1118/1.2240946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-FF-I-84: Comparison of LINACs Either Equipped with On-Board Imaging/cone-Beam CT Or CT-On-Rails for IGRT. Med Phys 2006. [DOI: 10.1118/1.2240764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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31
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SU-FF-T-262: Image-Guided Non-Invasive Stereotactic Radiosurgery. Med Phys 2006. [DOI: 10.1118/1.2241182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Implementation of a 6D Robotic Couch-Top for the Automation of Image-Guided Brain SRS and Spinal SRT. Int J Radiat Oncol Biol Phys 2005. [DOI: 10.1016/j.ijrobp.2005.07.871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Interim Results of a Phase I/II Evaluation of Stereotactic Body Radiotherapy for Spinal Metastases. Int J Radiat Oncol Biol Phys 2005. [DOI: 10.1016/j.ijrobp.2005.07.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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SU-FF-J-62: Image-Guided Radiotherapy Feasibility Study Using Kilo-Voltage Cone-Beam CT Images for Patient Alignment Verification. Med Phys 2005. [DOI: 10.1118/1.1997608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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SU-FF-J-99: Automation of Image Registration and Verification for Image-Guided Stereotactic Body Radiotherapy. Med Phys 2005. [DOI: 10.1118/1.1997645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
An integrated treatment delivery system for conformal stereotactic radiosurgery (CSRS) and radiotherapy (CSRT) has been developed through a collaboration involving Siemens Medical Systems, Inc., Tyco/Radionics, Inc., and The University of Texas M. D. Anderson Cancer Center. The system consists of a 6-MV linear accelerator (LINAC) equipped with a Tyco/Radionics miniature multileaf collimator (mMLC). For the conventional SRS treatment, the circular collimator housing can be attached to the opening window of the mMLC. The treatment delivery system is integrated with a radiotherapy treatment planning system and a record-and-verify system. The purpose of this study is to report the characteristics, performance, benefits, and the clinical applications of this delivery system. The technical specifications of the LINAC and mMLC were tested, and all the specifications were met. The 80% to 20% penumbral width for each mMLC leaf is approximately 3 mm and is nearly independent of the off-axis positions of a leaf. The maximum interleaf leakage is 1.4% (1.1% on average) and the maximum intra-leaf leakage is 1.0% (0.9% on average). The leaf position precision is better than 0.5 mm for all the leaves. The integration of the SRS/SRT treatment planning system, mMLC, and LINAC has been evaluated successfully for transferring the patient treatment data file through radiotherapy treatment planning system to the patient information and treatment record-and-verify server and the mMLC controller. Subsequently, the auto-sequential treatment delivery for SRS, CSRS/CSRT, and the step-and-shoot intensity-modulated radiotherapy has also been tested successfully. The accuracy of dose delivery was evaluated for a 2-cm spherical target in a Radiological Physics Center SRS head phantom with GAFChromic films and TLD. Five non-coplanar arcs, using a 2-cm diameter circular collimator, were used for this simulation treatment. The accuracy to aim the center of the spherical target was within 0.5 mm and the deviation of dose delivery to the isocenter of the target was within 2% of the calculated dose. For the irregularly shaped tumor, a tissue-equivalent head phantom was used to evaluate the accuracy of dose delivery for using either geometric conformal treatment or IMRT. The accuracy of dose delivery to the isocenter was within 2% and 3% of the calculated dose, respectively. From October 26, 1999 to September 30, 2002, we treated over 400 SRS patients and 70 SRT patients. Four representative cases are presented to illustrate the capabilities of this dedicated unit in performing conventional SRS, CSRS, and CSRT. For all the cases, the geometric conformal-plan dose distributions showed a high degree of conformity to the target shape. The degree of conformity can be evaluated using the target-volume-ratio (TVR). Our preferred TVR values for highly conformed dose distributions range from 1.6 to 2.0. The patient setup reproducibility for the Gill-Thomas-Cosman (GTC) noninvasive head frame ranges from 0.5 to 1 mm, and the head and neck noninvasive frame is within 2 mm. The integrated treatment delivery system offers excellent conformation for complicated planning target volumes with the stereotactic setup approach, ensuring that dose delivery can be achieved within the specified accuracy. In addition, the treatment time is comparable with that of single isocenter multiple-arc treatments.
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MESH Headings
- Brain Neoplasms/radiotherapy
- Brain Neoplasms/secondary
- Brain Neoplasms/surgery
- Carcinoma, Renal Cell/radiotherapy
- Carcinoma, Renal Cell/secondary
- Humans
- Kidney Neoplasms/pathology
- Lymphoma, Large B-Cell, Diffuse/radiotherapy
- Nasopharyngeal Neoplasms/radiotherapy
- Neoplasm Recurrence, Local/radiotherapy
- Particle Accelerators/instrumentation
- Radiosurgery/instrumentation
- Radiosurgery/methods
- Radiotherapy Planning, Computer-Assisted/methods
- Radiotherapy, Conformal/instrumentation
- Radiotherapy, Conformal/methods
- Radiotherapy, High-Energy/instrumentation
- Radiotherapy, High-Energy/methods
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An integrated treatment delivery system for CSRS and CSRT and clinical applications. J Appl Clin Med Phys 2003. [DOI: 10.1120/1.1602191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Conformity of dose distribution and setup accuracy comparable to invasive head frame using an mlc and an unique positioning device with GTC frame for SRT. Int J Radiat Oncol Biol Phys 2001. [DOI: 10.1016/s0360-3016(01)02542-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Evaluating psychosocial nursing interventions for cardiac clients and their caregivers: a case study of the community rehabilitation network in Hong Kong. J Adv Nurs 2001; 35:393-401. [PMID: 11489024 DOI: 10.1046/j.1365-2648.2001.01856.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIM OF THE STUDY The purpose of this exploratory study was to describe the type and nature of psychosocial nursing interventions provided for cardiac clients in Hong Kong's Community Rehabilitation Centres (CRNs). DESIGN/METHODS Using a two-phase case study design data were collected from nurses, cardiac clients and their caregivers. The initial phase focused on identifying the types of psychosocial interventions provided. These data were obtained by observing nursing activities and the keeping of daily journals by the nurses. The second phase acquired data from structured telephone interviews, that reviewed clients' perceptions of the psychosocial interventions provided by the nurses and face-to-face interviews with clients and their caregivers. FINDINGS These findings revealed that the nurses' interpersonal skills of information giving, social support and counselling were highly valued by cardiac clients and their caregivers. Both clients and caregivers outlined a concern about the lack of individual care and this was reflected in the focus of the CRN on group processes. CONCLUSION Recommendations for psychosocial cardiac care are made for public health nurses and nurses working in community settings.
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A pencil-beam photon dose algorithm for stereotactic radiosurgery using a miniature multileaf collimator. Med Phys 1998; 25:841-50. [PMID: 9650171 DOI: 10.1118/1.598294] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A computer-controlled miniature multileaf collimator (MMLC) with 4 mm leaf width and a maximum field size of 6 cm X 6 cm has been designed as a tertiary beam-shaping device for linac-based stereotactic radiosurgery. The purpose of this study is to develop an accurate and efficient dose calculation model for use with the MMLC. A pencil-beam based algorithm using a sum of three Gaussian kernels was developed to model the off-axis ratio of MMLC fields. Because the kernel integration over a rectangular field can be solved in closed form, dose to any point from an arbitrary MMLC field can be calculated efficiently by summing dose contribution from a set of rectangular apertures and transmission blocks that model individual leaf openings or leaf transmissions. The model uses an effective rectangular field and equivalent square method for determination of depth dose and dose output. Results showed that the calculated percentage depth dose was within 1% and output factor was within 1.5% of measured data. The parameters of the pencil beam kernels were extracted by fitting measured off-axis profiles for a few field sizes at a few depths. The accuracy of the calculated off-axis ratio was tested by comparison with measured data for a number of MMLC fields. The algorithm was shown to be accurate to within 1.5% or 1 mm for off-axis ratios. The algorithm computes at a speed of 34,600 data points per second on a DEC Alpha server model 2000/433 (Digital Equipment Corp., Maynard, MA), which is about 15 times faster than a Clarkson-type summation method.
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Verification of radiosurgery target point alignment with an electronic portal imaging device (EPID). Med Phys 1997; 24:263-7. [PMID: 9048367 DOI: 10.1118/1.598070] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A procedure has been developed using an electronic portal imaging device (EPID) to verify that the center of a patient's lesion is aligned with the center of a treatment cone prior to treatment in a linac-based stereotactic radiosurgery procedure. The coordinates of the lesion center are set on the Brown-Roberts-Wells phantom base using a target simulator. A 3 mm tungsten ball, mounted on the target simulator, is used as the reference point for the planned isocenter. The target simulator is then attached to an adapter mounted on the linac couch, and an EPID image of the simulated target is acquired. The center of the circular-shaped radiation field is calculated from the centroid of the segmented EPID image, and the center of the tungsten ball is identified by an automated computer search algorithm. A summation filter is used to find the position of the lowest radiation intensity coincident with the center of the ball. The alignment error is defined as the difference between the center of the radiation field and the center of the ball. The accuracy of this method was tested and found to be within 0.2 mm. The advantage of the EPID-based procedure is that it can give quantitative offset values quickly for immediate readjustment. We have found that the method is also a convenient tool for testing room laser alignment and the accuracy of the treatment cones.
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An evaluation of the effectiveness of public health nursing: a case study of the maternal and child health centres in Hong Kong. Int J Nurs Stud 1996; 33:442-54. [PMID: 8836768 DOI: 10.1016/0020-7489(96)00002-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The aim of this study was to evaluate the effectiveness of public health nursing in Hong Kong using the maternal and child health centres as a case study. The case study design, employing both qualitative and quantitative methods of data collection, focused on clients' and nurses' perceptions of the effectiveness of care. The data analysis identified three important factors influencing the effectiveness of care: the need for a health needs data base, the organisation of care and service provision. From these findings the authors suggest that a health needs data base plays an essential role in measuring the effectiveness of care in public health nursing.
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Abstract
Surgery and radiosurgery are effective treatment modalities for brain metastasis. To compare the results of these treatment modalities, the authors followed 13 patients treated by radiosurgery and 62 patients treated by surgery who were retrospectively matched. Patients were matched according to the following criteria: histological characteristics of the primary tumor, extent of systemic disease, preoperative Karnofsky Performance Scale score, time to brain metastasis, number of brain metastases, and patient age and sex. For patients treated by radiosurgery, the median size of the treated lesion was 1.96 cm3 (range 0.41-8.25 cm3) and the median dose was 20 Gy (range 12-22 Gy). The median survival was 7.5 months for patients treated by radiosurgery and 16.4 months for those treated by surgery; this difference was found to be statistically significant using both univariate (p = 0.0018) and multivariate (p = 0.0009) analyses. The difference in survival was due to a higher rate of mortality from brain metastasis in the radiosurgery group than in the surgery group (p < 0.0001) and not due to a difference in the rate of death from systemic disease (p = 0.28). Log-rank analysis showed that the higher mortality rate found in the radiosurgery group was due to a greater progression rate of the radiosurgically treated lesions (p = 0.0001) and not due to the development of new brain metastasis (p = 0.75). On the basis of their data, the authors conclude that surgery is superior to radiosurgery in the treatment of brain metastasis. Patients who undergo surgical treatment survive longer and have a better local control. The data lead the authors to suggest that the indications for radiosurgery should be limited to surgically inaccessible metastatic tumors or patients in poor medical condition. Surgery should remain the treatment of choice whenever possible.
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Technique for a spaced, vacuum-formed impression tray. J Prosthet Dent 1991; 65:325-6. [PMID: 2051374 DOI: 10.1016/0022-3913(91)90185-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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[Soldering bridges after porcelain blending]. DIE QUINTESSENZ DER ZAHNTECHNIK 1990; 16:1109-18. [PMID: 1983041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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46
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[Position accurate precision stump model in restorative dentistry]. DIE QUINTESSENZ DER ZAHNTECHNIK 1989; 15:683-97. [PMID: 2626546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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47
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Anterior porcelain laminate veneers: clinical and laboratory procedures. QUINTESSENCE OF DENTAL TECHNOLOGY 1986; 10:493-9. [PMID: 3532212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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48
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The combination acid etched retained and fixed partial denture. QUINTESSENCE INTERNATIONAL (BERLIN, GERMANY : 1985) 1986; 17:165-71. [PMID: 3517929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Autopolymerized acrylic resin record bases and occlusion rims for complete dentures. QUINTESSENCE OF DENTAL TECHNOLOGY 1984; 8:623-31. [PMID: 6396743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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50
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Acid etched retainers combined with intracoronal attachments. QUINTESSENCE OF DENTAL TECHNOLOGY 1984; 8:483-7. [PMID: 6385148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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