bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Outcome Assessments in Patients with Overactive Bladder Receiving Anticholinergics
Authors: LEE Hye Won , LEE Young‐Suk , BAICK Sang‐Hoon , LEE Kyu‐Sung
Published: June 2009

Objectives: Patient‐reported outcomes (PRO) reflect treatment benefits from the patient's perspective, and are a subjective method of evaluating the efficacy of overactive bladder (OAB) treatment. We examined the changes in voiding diaries and health‐related quality of life (HRQL) according to patient‐perceived treatment benefits in patients with OAB receiving propiverine.

Methods: Thirty‐two patients (mean age ± S.D: 55.1 ± 14.1 years) with OAB were treated with 20 mg propiverine once daily for 12 weeks. The 3‐day voiding diary and the Korean version of the Overactive Bladder Questionnaire (OABq), which includes an eight‐item bothersome symptom scale, as well as 25 HRQL items, were assessed at baseline and at 12 weeks. Finally, patient perception of treatment benefit was evaluated as “no benefit,”“little benefit,” or “much benefit” after treatment.

Results: According to patients' perceptions of treatment benefits, 16 (50%) patients perceived “much benefit” from their treatment (group A) and 16 (50%) patients perceived “little benefit” or “no benefit” from their treatment (group B). In both groups, there were significant improvements in the micturation parameters, OABq bothersome symptoms, and total HRQL score after 12 weeks of treatment (P < 0.05). Although there were no significant differences in the voiding diary parameters between the two groups, patients in group A showed significant improvement of the OABq bothersome symptom and total HRQL score compared to group B (P < 0.05).

Conclusion: Anticholinergic treatment improves both OAB symptoms and HRQL, and patients' perceptions of treatment benefits correlate better with the OABq than with the voiding diary parameters.
Challenge of One‐incision Midurethral Sling for Female Stress Urinary Incontinence: Current Results
Authors: CHOO Myung‐Soo
Published: June 2009

As a result of the understanding of the pathogenesis of stress urinary incontinence in females, a tension‐free vaginal tape procedure has been introduced based on integral theory and is now widely used because of its minimal invasiveness and high success rate. Modifications over the last 10 years include changes to mesh type, technique and route of insertion of sling materials. Long‐term efficacy and quality of life data of the different midurethral sling (MUS) procedures are available. However, complications, such as bladder and urethral injury, persistent groin pain, vascular and nerve injury, and voiding difficulty can occur. Recently, one‐incision MUS procedures without tape outlets have been developed to reduce surgical invasiveness and lower the risk of complications. However, few studies have reported the outcomes following one‐incision MUS procedures. The present report reviews studies of one‐incision MUS procedures to determine whether this technique can be used in the place of older techniques. It appears that while one‐incision MUS procedures may be associated with lower complication rates, success rates may also be lower, although the latest results are promising. It takes a long time for the surgeon to become an expert in performing the technique. Proper sling tension and correct surgical plane are very important. At the moment it seems that the one‐incision sling cannot replace older slings. We need to wait for and review the long‐term prospective results of the new and minimally invasive one‐incision sling for the treatment of female stress urinary incontinence.
Effects of Exenatide on Plasma Glucose and Insulin Concentrations in Alpacas
Authors: Smith C.C. , Cebra C.K.
Published: June 2009

Background:Exenatide is a degradation‐resistant glucagon‐like peptide 1 agonist used in the treatment of diabetes mellitus. It enhances the insulin response to hyperglycemia. Because of a poor insulin response, adult camelids are susceptible to hyperglycemia from stress, glucose administration, or energy metabolism disorders. Insulin often is administered to decrease plasma glucose concentration, but this approach has disadvantages such as the risk of hypoglycemia. Noninsulin medications targeting the incretin hormone pathway, such as exenatide, are providing alternate treatment options.

Hypothesis/Objectives:Exenatide will decrease plasma glucose and increase insulin concentrations in alpacas.

Animals:Six healthy adult alpacas.

Methods:After food was withheld for 8 hours, alpacas were given, on subsequent days in a randomly determined order, either 0.2 μg/kg of exenatide or similar volume of isotonic saline SC. Blood samples were collected before and 15, 30, 45, 60, 75, 90, 105, and 120 minutes after treatment. A rapid dextrose (0.5 g/kg) injection was given after the time 60 samples. Plasma glucose and insulin concentrations were measured at each time point.

Results:Alpacas had significantly (P= < .001–.015) lower plasma glucose and higher insulin concentrations for the hyperglycemic period after receiving exenatide than after saline injections. Colic signs were observed in 5 of 6 alpacas treated with exenatide.

Conclusions and Clinical Importance:Exenatide appeared to increase insulin release and decrease plasma glucose concentrations in hyperglycemic alpacas. These findings are similar to findings in humans and could support therapeutic usage of exenatide in alpacas. However, induction of colic may limit practical application.
Steroid Responsive Meningitis‐Arteritis: A Prospective Study of Potential Disease Markers, Prednisolone Treatment, and Long‐Term Outcome in 20 Dogs (2006–2008)
Authors: Lowrie M. , Penderis J. , McLaughlin M. , Eckersall P.D. , Anderson T.J.
Published: June 2009

Background:Previous multidrug studies have identified the value of prednisolone in treating steroid responsive meningitis‐arteritis (SRMA) and the potential value of acute phase proteins (APPs) and immunoglobulin A (IgA) in diagnosis and monitoring.

Hypothesis:(1) Prednisolone monotherapy is a successful immunosuppressive modality in the treatment of SRMA; (2) protein markers are useful in identifying the potential for relapse.

Animals:Twenty client‐owned dogs with SRMA presented to the University of Glasgow Small Animal Hospital between May 2006 and May 2008.

Methods:A prospective, observational study: CBC, biochemistry, and cerebrospinal fluid (CSF) analyses were performed. C‐reactive protein (CRP), serum amyloid‐A, α‐1‐acid glycoprotein, and haptoglobin (Hp) were assessed in the serum. IgA concentrations were determined in the serum and CSF.

Results:Clinical resolution of SRMA was achieved in all 20 dogs. Serum CRP concentration remained increased at remission in 16/20 dogs whereas CSF cytology was within normal limits in 20/20 dogs. Serum APPs decreased significantly on treatment (P< .05) except Hp, which remained unaltered. Serum and CSF IgA concentrations remained increased for the duration of treatment.

Conclusions and Clinical Importance:The prednisolone regimen presented was successful in treating SRMA without the need for additional drugs. Serum APPs are of use in the diagnosis and management of SRMA, particularly in relation to identifying relapse. Serum and CSF IgA concentrations remain increased throughout disease, aiding in diagnosis but not contributing to the management of SRMA.
Polymicrogyria in Standard Poodles
Authors: Jurney C. , Haddad J. , Crawford N. , Miller A.D. , Winkle T.J. Van , Vite C.H. , Sponenberg P. , Inzana K.D. , Cook C.R. , Britt L. , O'Brien D.P.
Published: June 2009

Background: Polymicrogyria is a disorder of cerebrocortical migration resulting in increased numbers of small, disorganized gyri. This disorder occurs in Standard Poodles and in cattle.

Objectives: To describe the clinical, electroencephalographic, imaging, and histopathologic features in poodles with polymicrogyria.

Animals: Five Standard Poodles with histologically confirmed polymicrogyria.

Methods: Retrospective case series. Cases were obtained by personal communication with 1 of 2 authors (TJVW, DPO).

Results: All dogs had cortical blindness and other neurologic abnormalities including gait and behavioral changes. Magnetic resonance imaging of 3 dogs showed multiple disorganized gyri, which were especially apparent on T2‐weighted dorsal plane images. Electroencephalogram (EEG) of 1 dog revealed epileptiform discharges, including both spike and spike and wave discharges with voltage maximum potentials over the parietal/occipital region. The EEG supported that the repetitive behavior displayed by the dog was a complex partial motor seizure. One dog had concurrent hydrocephalus. All dogs had occipital lobe involvement and 2 dogs had involvement of other lobes.

Clinical Importance: The cases presented here demonstrate a larger age range (7 weeks to 5 years) and a decreased frequency of associated hydrocephalus when compared with the previous report.
Effect of Repeated Arthrocentesis on Cytologic Analysis of Synovial Fluid in Dogs
Authors: Berg R.I.M. , Sykes J.E. , Kass P.H. , Vernau W.
Published: June 2009

Background: Serial arthrocentesis and synovial fluid examination can be used to monitor treatment efficacy in immune‐mediated polyarthritis (IMPA), but whether this procedure induces inflammation that interferes with test result interpretation is unknown.

Objectives: The aim of this study was to determine the effect of repeated arthrocentesis on synovial fluid cytology in healthy dogs.

Animals: Nine healthy client‐owned dogs.

Methods: Prospective study. Arthrocentesis was performed under sedation on 4 joints (both carpi, 1 tarsus, 1 stifle) on each dog every 3 weeks, a total of 4 times. Automated cell counts were done on stifle fluid, smears were made, and differential cell counts done on smears from all joints. Slides were evaluated microscopically for erythrocyte numbers, total nucleated cell count, differential cell count, and cell morphology. Data were analyzed by 2‐way analysis of variance.

Results: A total of 144 synovial fluid samples were examined. Repeated arthrocentesis was not associated with increases in synovial fluid neutrophil numbers. Mild mononuclear inflammation was detected in 13 samples from 6 dogs.

Conclusions and Clinical Importance: Serial arthrocentesis at 3‐week intervals can rarely be associated with mild mononuclear joint inflammation, but does not appear to induce neutrophilic inflammation, at least in healthy dogs, and can be useful to monitor treatment response in canine IMPA.
Field Safety and Efficacy of Protamine Zinc Recombinant Human Insulin for Treatment of Diabetes Mellitus in Cats
Authors: Nelson R.W. , Henley K. , Cole C. ,   the PZIR Clinical Study Group
Published: June 2009

Background:This study describes the efficacy of a new protamine zinc recombinant human insulin (PZIR) preparation for treating diabetic cats.

Objective:To evaluate effects of PZIR on control of glycemia in cats with newly diagnosed or poorly controlled diabetes mellitus.

Animals:One hundred and thirty‐three diabetic cats 120 newly diagnosed and 13 previously treated.

Methods:Prospective, uncontrolled clinical trial. Cats were treated with PZIR twice daily for 45 days. Control of glycemia was assessed on days 7, 14, 30, and 45 by evaluation of change in water consumption, frequency of urination, appetite, and body weight, serum fructosamine concentration, and blood glucose concentrations determined 1, 3, 5, 7, and 9 hours after administration of PZIR. Adjustments in dosage of PZIR were made as needed to control glycemia.

Results:PZIR administration resulted in a significant decrease in 9‐hour mean blood glucose (199 ± 114 versus 417 ± 83 mg/dL,X± SD,P< .001) and serum fructosamine (375 ± 117 versus 505 ± 96 μmol/L,P< .001) concentration and a significant increase in mean body weight (5.9 ± 1.4 versus 5.4 ± 1.5 kg,P= .017) in 133 diabetic cats at day 45 compared with day 0, respectively. By day 45, polyuria and polydipsia had improved in 79% (105 of 133), 89% (118 of 133) had a good body condition, and 9‐hour mean blood glucose concentration, serum fructosamine concentration, or both had improved in 84% (112 of 133) of the cats compared with day 0. Hypoglycemia (<80 mg/dL) was identified in 151 of 678, 9‐hour serial blood glucose determinations and in 85 of 133 diabetic cats. Hypoglycemia causing clinical signs was confirmed in 2 diabetic cats.

Conclusions and Clinical Relevance:PZIR is effective for controlling glycemia in diabetic cats and can be used as an initial treatment or as an alternative treatment in diabetic cats that do not respond to treatment with other insulin preparations.
Idiopathic Eosinophilic Masses of the Gastrointestinal Tract in Dogs
Authors: Lyles S.E. , Panciera D.L. , Saunders G.K. , Leib M.S.
Published: June 2009

Background: Eosinophilic inflammation of the gastrointestinal tract of dogs occurs in numerous disorders, typically resulting in diffuse intestinal thickening. Rarely, eosinophilic masses have been reported.

Objective: Describe a series of dogs with 1 or more idiopathic eosinophilic gastrointestinal masses (IEGM) to better characterize the clinical features, treatment, and prognosis.

Animals: Seven dogs with 1 or more gastrointestinal masses composed primarily of eosinophilic infiltrates for which no underlying cause was found.

Methods: Retrospective case series.

Results: Rottweilers and purebred, large breed dogs predominated. Dogs were middle‐aged and typically had chronic signs of upper or lower gastrointestinal disease. Decreased appetite, vomiting, and evidence of gastrointestinal hemorrhage were present in the majority of cases. An abdominal or rectal mass was frequently noted on physical examination. Common laboratory abnormalities included peripheral eosinophilia, mature neutrophilia, hypoproteinemia, and hypocholesterolemia. The masses were histologically composed of moderate to severe eosinophilic infiltrates, which were often transmural and accompanied by fibrosis. All dogs treated with surgery alone died of complications of their disease. Treatment with corticosteroids and ivermectin improved clinical signs, caused resolution of eosinophilic infiltrates, and prolonged survival in most dogs treated medically.

Conclusions and Clinical Importance: These findings suggest that the prognosis for dogs with IEGM may be good when recognized and managed appropriately. When surgery is performed, medical treatment should also be added.
Peritoneald‐Dimer Concentration for Assessing Peritoneal Fibrinolytic Activity in Horses with Colic
Authors: Delgado M.A. , Monreal L. , Armengou L. , Ríos J. , Segura D.
Published: June 2009

Background:Plasmad‐dimer concentration is a useful marker to assess systemic coagulation and fibrinolytic activities in humans, dogs, and horses. Peritoneal fibrinolytic activity increases in horses with colic, especially in horses with endotoxin in the peritoneal fluid.

Hypothesis/Objectives:Peritoneald‐dimer concentration can be used to assess peritoneal fibrinolytic activity in horses with severe gastrointestinal (GI) disorders and altered peritoneal fluid.

Animals:Two hundred and twenty‐one colic horses and 15 control horses.

Methods:Prospective observational clinical study. Blood and peritoneal fluid were collected on admission. Horses were grouped according to diagnosis, peritoneal fluid analysis, and outcome. Peritoneald‐dimer concentration was determined, together with peritoneal tissue‐plasminogen activator (t‐PA) and plasminogen activator inhibitor (PAI‐1) activities. Plasmad‐dimer concentration also was measured.

Results:Peritoneald‐dimer concentration was significantly higher in all colic groups compared with controls, and in horses with enteritis, peritonitis, and ischemic disorders compared with horses with large intestinal obstructions. Peritoneald‐dimer concentration was significantly higher in horses with altered peritoneal fluid (modified transudate and exudate) compared with horses with normal peritoneal fluid analysis. Plasmad‐dimer concentration also was significantly higher in the peritonitis group, and in horses with altered peritoneal fluid analysis. Peritoneal and plasmad‐dimer concentrations also were significantly higher in nonsurvivors. Peritoneald‐dimer concentration was significantly correlated with decreased peritoneal t‐PA activity and increased peritoneal PAI‐1 activity.

Conclusions and Clinical Importance:Peritoneald‐dimer concentration is markedly higher in severe GI disorders, and it can be used to assess peritoneal fibrinolytic activity in horses with colic.
Analytical and Experimental Analysis of a High Temperature Mercury Thermosyphon
Authors: Vieira da Cunha André Felippe , Mantelli Marcia B. H.
Published: June 2009

High temperature thermosyphons are devices designed to operate at temperatures above 400°C. They can be applied in many industrial applications, including heat recovery from high temperature air fluxes. After a short literature review, which shows a deficiency of models for liquid metal thermosyphons, an analytical model, developed to predict the temperature distribution and the overall thermal resistance, is shown. In this model, the thermosyphon is divided into seven regions: three regions for the condensed liquid, including the condenser, adiabatic region, and evaporator; one region for vapor; one for the liquid pool; one for the noncondensable gases; and another for the tube wall. The condensation phenomenon is modeled according to the Nusselt theory for condensation in vertical walls. Numerical methods are used to solve the resulting equations and to determine the temperature distribution in the tube wall. Ideal gas law is applied for the noncondensable gases inside the thermosyphon, while the evaporator and condenser heat transfer coefficients are obtained from literature correlations. Experimental tests are conducted for thermosyphon with mercury as working fluid, designed and constructed in the laboratory. The results for two thermosyphons with different geometry configurations are tested: one made of a finned tube in the condenser region and another of a smooth tube. The finned tube presents lower wall temperature levels when compared with the smooth tube. The experimental data are compared with the proposed model for two different liquid pool heat transfer coefficients. It is observed that the comparison between the experimental data and theoretical temperature profiles is good for the condenser region. For the evaporator, where two distinct regions are observed (liquid film and pool), the comparison is not so good, independent of the heat transfer coefficient used. In a general sense, the model has proved to be a useful tool for the design of liquid metal thermosyphons.
Electron-Phonon Interaction Model and Its Application to Thermal Transport Simulation During Electrostatic Discharge Event in NMOS Transistor
Authors: Jin Jae Sik , Lee Joon Sik
Published: June 2009

First, the electron-phonon interaction model, which has recently been developed by authors for thermal predictions within the silicon devices in micro/nanoscales, is verified through the comparison with the experimental measurement of average temperature rise in the channel region of a silicon-on-insulator (SOI) transistor. The effect of the silicon layer thickness of the SOI transistor on phonon thermal characteristics is also investigated. It is found that the thickness effect on the peak temperature of the optical phonon mode in the hot spot region is negligible due to its very low group velocity. Thus the acoustic phonons in a specific frequency band, which has the highest scattering rate with the optical phonons, experience relatively less reduction in the peak temperature as the silicon layer thickness increases. Second, the electron-phonon interaction model is applied to the transient thermal transport simulation during the electrostatic discharge (ESD) event in an n-type metal-oxide-semiconductor (NMOS) transistor. The evolution of the peak temperature in the hot spot region during the ESD event is simulated and compared with that obtained by the previous full phonon dispersion model, which treats the electron-phonon scattering as a volumetric heat source. The results show that the lower group velocity acoustic phonon modes (i.e., higher frequency) and optical mode of negligible group velocity acquire high energy density from electrons during the ESD event, which might cause the devices melting problem. The heat transfer rates by individual phonon modes are also examined, and it is found that the key parameter to determine the phonon heat transfer rate during the ESD event is the product of the phonon specific heat and the scattering rates with higher energy density phonons in the hot spot region.
Heat Transfer Enhancement Due to Frequency Doubling and Ruelle–Takens–Newhouse Transition Scenarios in Symmetric Wavy Channels
Authors: Guzmán Amador M. , Hormazabal Raúl A. , Aracena Tania A.
Published: June 2009

Heat transfer enhancement characteristics, through a transition scenario of flow bifurcations in symmetric wavy wall channels, are investigated by direct numerical simulations of the mass, momentum, and energy equations using spectral element methods. Flow bifurcations, transition scenarios, and heat transfer characteristics are determined by increasing the Reynolds numbers from a laminar to a transitional flow for the geometrical aspect ratios r=0.125 and r=0.375. The numerical results demonstrate that the transition scenario to transitional flow regimes depends on the aspect ratio. For r=0.375, the transition scenario is characterized by one Hopf flow bifurcation in a frequency-doubling transition scenario, where further increases in the Reynolds number always lead to periodic flows; whereas, for r=0.125, the transition scenario is characterized by a first Hopf flow bifurcation from a laminar to a time-dependent periodic flow and a second Hopf flow bifurcation from a periodic to a quasiperiodic flow. For r=0.125, the flow bifurcation scenario is similar to the Ruelle–Takens–Newhouse (RTN) transition scenario to Eulerian chaos observed in asymmetric wavy and grooved channels. The periodic and quasiperiodic flows are characterized by fundamental frequencies ω1, and ω1 and ω2, respectively. For the aspect ratio r=0.375, the Nusselt number increases slightly as the Reynolds number increases in the laminar regime until it reaches a critical Reynolds number of Rec≈126. As the flow becomes periodic, and then quasiperiodic, the Nusselt number continuously increases with respect to the laminar regime, up to a factor of 4, which represents a significant heat transfer enhancement due to a better flow mixing.
Numerical Modeling of Chaotic Mixing in Electroosmotically Stirred Continuous Flow Mixers
Authors: Kim Ho Jun , Beskok Ali
Published: June 2009

We present numerical studies of particle dispersion and species mixing in a ζ potential patterned straight microchannel. A continuous flow is generated by superposition of a steady pressure-driven flow and time-periodic electroosmotic flow induced by a streamwise ac electric field. ζ potential patterns are placed critically in the channel to achieve spatially asymmetric time-dependent flow fields that lead to chaotic stirring. Parametric studies are performed as a function of the Strouhal number (normalized ac frequency), while the mixer geometry, ratio of the Poiseuille flow and electroosmotic velocities, and the flow kinematics (Reynolds number) are kept constant. Lagrangian particle tracking is employed for observations of particle dispersion. Poincaré sections are constructed to identify the chaotic and regular zones in the mixer. Filament stretching and the probability density function of the stretching field are utilized to quantify the “locally optimum” stirring conditions and to demonstrate the statistical behavior of fully and partially chaotic flows. Numerical solutions of the species transport equation are performed as a function of the Peclet number (Pe) at fixed kinematic conditions. Mixing efficiency is quantified using the mixing index, based on standard deviation of the scalar species distribution. The mixing length (lm) is characterized as a function of the Peclet number and lm∝ln(Pe) scaling is observed for the fully chaotic flow case. Objectives of this study include the presentation and characterization of the new continuous flow mixer concept and the demonstration of the Lagrangian-based particle tracking tools for quantification of chaotic strength and stirring efficiency in continuous flow systems.
Thermal Conductivity Measurements of Nylon 11-Carbon Nanofiber Nanocomposites
Authors: Moore Arden L. , Cummings Antonette T. , Jensen Justin M. , Shi Li , Koo Joseph H.
Published: June 2009

Carbon nanofibers (CNFs) were incorporated into nylon 11 to form nylon 11-carbon nanofiber nanocomposites via twin screw extrusion. Injection molding has been employed to fabricate specimens that possess enhanced mechanical strength and fire retardancy. The thermal conductivity of these polymer nanocomposites was measured using a guarded hot plate method. The measurement results show that the room temperature thermal conductivity increases with the CNF loading from 0.24±0.01 W/m K for pure Nylon 11 to 0.30±0.02 W/m K at 7.5 wt % CNF loading. The effective medium theory has been used to determine the interface thermal resistance between the CNFs and the matrix to be in the range of 2.5–5.0×10−6 m2 K/W from the measured thermal conductivity of the nanocomposite.
Thermal Homogenization in Spherical Reservoir by Electrohydrodynamic Conduction Phenomenon
Authors: Yazdani Miad , Seyed-Yagoobi Jamal
Published: June 2009

Effect of electric conduction phenomenon on the mixing mechanism is studied numerically to thermally homogenize a dielectric liquid with an initial nonuniform temperature distribution. The fluid is stored in a spherical reservoir, and the electrodes are embedded on the reservoir surface such that the resultant local electric body forces mix the fluid. The electric field and electric body force distributions along with the resultant velocity field at the final steady-state condition are presented. The mixing mechanism is illustrated by the time evolution of temperature distribution inside the reservoir. The effects of primary dimensionless numbers on the mixing time are studied.
Three-Dimensional Numerical Study of Flow and Heat Transfer Enhancement Using Vortex Generators in Fin-and-Tube Heat Exchangers
Authors: Chu P. , He Y. L. , Tao W. Q.
Published: June 2009

In this paper, a three-dimensional numerical investigation was performed for heat transfer characteristics and flow structure of full scale fin-and-tube heat exchangers with rectangular winglet pair (RWP). For the Reynolds number ranging from 500 to 880, the baseline configuration (without RWP) is compared with three enhanced configurations (with RWP): inline-1RWP case, inline-3RWP case, and inline-7RWP case. It was found that the air-side heat transfer coefficient improved by 28.1–43.9%, 71.3–87.6%, and 98.9–131% for the three enhanced configurations, with an associated pressure drop penalty increase of 11.3–25.1%, 54.4–72%, and 88.8–121.4%, respectively. An overall performance comparison was conducted by using the London area goodness factor. It is revealed that among the three enhanced configurations, the inline-1RWP case obtains the best overall performance, and the inline-3RWP case is better than the inline-7RWP case. The numerical results were also analyzed on the basis of the field synergy principle to provide fundamental understanding of the relation between local flow structure and heat transfer augmentation. It was confirmed that the reduction in the average intersection angle between the velocity vector and the temperature gradient was one of the essential factors influencing heat transfer enhancement. The analysis also provides guidelines for where the enhancement technique is highly needed.
Numerical Analysis of a Two-Dimensional Jet Impinging on an Oscillated Heat Transfer Surface
Authors: Ichimiya Koichi , Watanabe Shuichi
Published: June 2009

Numerical analyses were performed to determine the oscillation effect of an impingement surface on the impingement heat transfer and flow with a confined wall. As a moving boundary problem, two-dimensional governing equations were solved for the Reynolds numbers Re=200 and 500, the Prandtl number Pr=0.71, the dimensionless space between the nozzle and impingement surface H=1.0, and the Strouhal number Sf=0–1.0. Oscillation induced both the enhancement and depression of the local heat transfer. The local heat transfer was improved at a comparatively low frequency due to the flow fluctuation. On the other hand, at a high frequency, it was depressed due to the flow in an upper direction near the impingement surface. The oscillation effect spatially appeared downstream after the impingement.
Macro- to Microscale Boiling Heat Transfer From Metal-Graphite Composite Surfaces
Authors: Yang Wen-Jei , Zhang Nengli , Vrable Daniel L.
Published: June 2009

This paper introduces a novel heat transfer enhancement surface, referred to as metal-graphite composite surface. It is comprised of high thermal conductivity graphite microfibers interspersed within a metal matrix (copper or aluminum) to enhance the bubble formation at the nucleation sites, and significantly improve the nucleate boiling heat transfer. Experiments revealed that its boiling heat transfer enhancement is comparable or in some respect even superior to the commercially available boiling heat transfer enhancement surfaces such as porous boiling surface and integral roughness surface. In addition, it does not result in any extra pressure loss and it minimizes surface fouling. Macro- to microscale heat transfer phenomena of the composite surfaces is treated. Discussions include characteristics of the surface, enhancement mechanisms, critical heat flux, boiling thermal hysteresis, bubble generation, growth and departure, and applications in electronic cooling, and under reduced gravity conditions.
An investigation of signal performance enhancements achieved through innovative pixel design across several generations of indirect detection, active matrix, flat‐panel arrays
Authors: Antonuk Larry E. , Zhao Qihua , El‐Mohri Youcef , Du Hong , Wang Yi , Street Robert A. , Ho Jackson , Weisfield Richard , Yao William
Published: June 2009

Active matrix flat‐panel imager (AMFPI) technology is being employed for an increasing variety of imaging applications. An important element in the adoption of this technology has been significant ongoing improvements in optical signal collection achieved through innovations in indirect detection array pixel design. Such improvements have a particularly beneficial effect on performance in applications involving low exposures and/or high spatial frequencies, where detective quantum efficiency is strongly reduced due to the relatively high level of additive electronic noise compared to signal levels of AMFPI devices. In this article, an examination of various signal properties, as determined through measurements and calculations related to novel array designs, is reported in the context of the evolution of AMFPI pixel design. For these studies, dark, optical, and radiation signal measurements were performed on prototype imagers incorporating a variety of increasingly sophisticated array designs, with pixel pitches ranging from . For each design, detailed measurements of fundamental pixel‐level properties conducted under radiographic and fluoroscopic operating conditions are reported and the results are compared. A series of pitch arrays employing discrete photodiodes culminated in a novel design providing an optical fill factor of (thereby assuring improved x‐ray sensitivity), and demonstrating low dark current, very low charge trapping and charge release, and a large range of linear signal response. In two of the designs having 75 and pitches, a novel continuous photodiode structure was found to provide fill factors that approach the theoretical maximum of 100%. Both sets of novel designs achieved large fill factors by employing architectures in which some, or all of the photodiode structure was elevated above the plane of the pixel addressing transistor. Generally, enhancement of the fill factor in either discrete or continuous photodiode arrays was observed to result in no degradation in MTF due to charge sharing between pixels. While the continuous designs exhibited relatively high levels of charge trapping and release, as well as shorter ranges of linearity, it is possible that these behaviors can be addressed through further refinements to pixel design. Both the continuous and the most recent discrete photodiode designs accommodate more sophisticated pixel circuitry than is present on conventional AMFPIs – such as a pixel clamp circuit, which is demonstrated to limit signal saturation under conditions corresponding to high exposures. It is anticipated that photodiode structures such as the ones reported in this study will enable the development of even more complex pixel circuitry, such as pixel‐level amplifiers, that will lead to further significant improvements in imager performance.
A Monte Carlo investigation of Swank noise for thick, segmented, crystalline scintillators for radiotherapy imaging
Authors: Wang Yi , Antonuk Larry E. , El‐Mohri Youcef , Zhao Qihua
Published: June 2009

Thick, segmented scintillating detectors, consisting of 2D matrices of scintillator crystals separated by optically opaque septal walls, hold considerable potential for significantly improving the performance of megavoltage (MV) active matrix, flat‐panel imagers (AMFPIs). Initial simulation studies of the radiation transport properties of segmented detectors have indicated the possibility of significant improvement in DQE compared to conventional MV AMFPIs based on phosphor screen detectors. It is therefore interesting to investigate how the generation and transport of secondary optical photons affect the DQE performance of such segmented detectors. One effect that can degrade DQE performance is optical Swank noise (quantified by the optical Swank factor ), which is induced by depth‐dependent variations in optical gain. In this study, Monte Carlo simulations of radiation and optical transport have been used to examine and zero‐frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element‐to‐element pitches. For these detectors, and DQE were studied as a function of various optical parameters, including absorption and scattering in the scintillator, absorption at the top reflector and septal walls, as well as scattering at the side surfaces of the scintillator crystals. The results indicate that and DQE are only weakly affected by absorption and scattering in the scintillator, as well as by absorption at the top reflector. However, in some cases, these metrics were found to be significantly degraded by absorption at the septal walls and scattering at the scintillator side surfaces. Moreover, such degradations are more significant for detectors with greater thickness or smaller element pitch. At 1.016 mm pitch and with optimized optical properties, 40 mm thick segmented CsI:Tl and BGO detectors are predicted to provide DQE values of and 42%, corresponding to improvement by factors of and 42, respectively, compared to that of conventional MV AMFPIs.
Lesion quantification in oncological positron emission tomography: A maximum likelihood partial volume correction strategy
Authors: De Bernardi Elisabetta , Faggiano Elena , Zito Felicia , Gerundini Paolo , Baselli Giuseppe
Published: June 2009

A maximum likelihood (ML) partial volume effect correction (PVEC) strategy for the quantification of uptake and volume of oncological lesions in ‐FDG positron emission tomography is proposed. The algorithm is based on the application of ML reconstruction on volumetric regional basis functions initially defined on a smooth standard clinical image and iteratively updated in terms of their activity and volume. The volume of interest (VOI) containing a previously detected region is segmented by a ‐means algorithm in three regions: A central region surrounded by a partial volume region and a spill‐out region. All volume outside the VOI (background with all other structures) is handled as a unique basis function and therefore “frozen” in the reconstruction process except for a gain coefficient. The coefficients of the regional basis functions are iteratively estimated with an attenuation‐weighted ordered subset expectation maximization (AWOSEM) algorithm in which a 3D, anisotropic, space variant model of point spread function (PSF) is included for resolution recovery. The reconstruction‐segmentation process is iterated until convergence; at each iteration, segmentation is performed on the reconstructed image blurred by the system PSF in order to update the partial volume and spill‐out regions. The developed PVEC strategy was tested on sphere phantom studies with activity contrasts of 7.5 and 4 and compared to a conventional recovery coefficient method. Improved volume and activity estimates were obtained with low computational costs, thanks to blur recovery and to a better local approximation to ML convergence.
A self‐checking fiber optic dosimeter for monitoring common errors in brachytherapy applications
Authors: Yin Y. , Lambert J. , Yang S. , McKenzie D. R. , Jackson M. , Suchowerska N.
Published: June 2009

Scintillation dosimetry with optical fiber readout [fiber optic dosimetry (FOD)] requires accurate measurement of light intensity. It is therefore vulnerable to loss of calibration if any changes occur in the efficiency of the optical pathway between the scintillator and the light detector. The authors show in this article that common types of errors that arise during clinical use for brachytherapy applications can be quantified using a light emitting diode to stimulate the scintillator, the so‐called LED‐FOD method, in an integrated and easy‐to‐use control unit that incorporates a compact peripheral component interconnect extension for instrumentation. Common sources of error include bending and mechanical compression of the fiber optic components and changes in the temperature of the scintillator. The authors show that the method can detect all the common errors studied in this work and that different types of errors can result in different correlations between the LED stimulated signal and the brachytherapy source signal. For a single‐type error the LED‐FOD can be used easily for system diagnosis and validation with the possibility to correct the dosimeter reading if the correlation between the LED stimulated signal and the brachytherapy source signal can be defined. For more complex errors, resulting from two or more errors occurring simultaneously, the LED‐FOD method can also allow the clinician to make a judgment on the reliability of the dosimeter reading. This self‐checking method can enhance the clinical robustness of the FOD for achieving accurate dose control.
Multidivergent‐beam stationary cardiac SPECT
Authors: Zeng Gengsheng L. , Stevens Andrew M.
Published: June 2009

This article develops a stationary cardiac single photon emission computed tomography (SPECT) system using a novel multidivergent‐beam collimator. This stationary SPECT system is inexpensive to build, small, and able to acquire true dynamic SPECT data. Stationary cardiac SPECT systems with multipinhole technology already exist. The proposed approach is to replace the multipinhole collimators with the originally designed multidivergent‐beam collimators. The motivation for replacing the pinhole technology by divergent‐beam technology is based on the following facts. The resolution/sensitivity trade‐off for the pinhole is excellent (good resolution and good sensitivity) only in small object (e.g., small animal) imaging when it operates in the image magnifying mode. However, in large object (e.g., human) imaging, the resolution/sensitivity trade‐off is poor (poor resolution and poor sensitivity) when the pinhole operates in the image reducing mode. In a stationary system, the number of angular views is limited; thus, image reduction is necessary to obtain more view angles. In this image reducing situation, divergent‐beam collimation is able to provide better resolution and detection sensitivity than pinhole collimation. Computer simulations are carried out to verified the claims.
Field‐size effect of physical doses in carbon‐ion scanning using range shifter plates
Authors: Inaniwa Taku , Furukawa Takuji , Nagano Ai , Sato Shinji , Saotome Naoya , Noda Koji , Kanai Tatsuaki
Published: June 2009

A field‐size effect of physical doses was studied in scanning irradiation with carbon ions. For the target volumes of , , and , the doses along the beam axis within the spread‐out Bragg peaks reduced to 99.4%, 98.2%, and 96.0% of the dose for the target of , respectively. The present study revealed that the observed reductions can be compensated for by adopting the three‐Gaussian form of lateral dose distributions for the pencil beam model used in the treatment planning system. The parameters describing the form were determined through the irradiation experiments making flat concentric squared frames with a scanned carbon beam. Since utilizing the three‐Gaussian model in the dose optimization loop is at present time consuming, the correction for the field‐size effect should be implemented as a “predicted‐dose scaling factor.” The validity of this correction method was confirmed through the irradiation of a target of .
Computer‐aided diagnosis of pulmonary nodules on CT scans: Improvement of classification performance with nodule surface features
Authors: Way Ted W. , Sahiner Berkman , Chan Heang‐Ping , Hadjiiski Lubomir , Cascade Philip N. , Chughtai Aamer , Bogot Naama , Kazerooni Ella
Published: June 2009

The purpose of this work is to develop a computer‐aided diagnosis (CAD) system to differentiate malignant and benign lung nodules on CT scans. A fully automated system was designed to segment the nodule from its surrounding structured background in a local volume of interest (VOI) and to extract image features for classification. Image segmentation was performed with a 3D active contour method. The initial contour was obtained as the boundary of a binary object generated by ‐means clustering within the VOI and smoothed by morphological opening. A data set of 256 lung nodules (124 malignant and 132 benign) from 152 patients was used in this study. In addition to morphological and texture features, the authors designed new nodule surface features to characterize the lung nodule surface smoothness and shape irregularity. The effects of two demographic features, age and gender, as adjunct to the image features were also investigated. A linear discriminant analysis (LDA) classifier built with features from stepwise feature selection was trained using simplex optimization to select the most effective features. A two‐loop leave‐one‐out resampling scheme was developed to reduce the optimistic bias in estimating the test performance of the CAD system. The area under the receiver operating characteristic curve, , for the test cases improved significantly from to when the newly developed image features were included with the original morphological and texture features. A similar experiment performed on the data set restricted to primary cancers and benign nodules, excluding the metastatic cancers, also resulted in an improved test , though the improvement did not reach statistical significance . The two demographic features did not significantly affect the performance of the CAD system when they were added to the feature space containing the morphological, texture, and new gradient field and radius features. To investigate if a support vector machine (SVM) classifier can achieve improved performance over the LDA classifier, we compared the performance of the LDA and SVMs with various kernels and parameters. Principal component analysis was used to reduce the dimensionality of the feature space for both the LDA and the SVM classifiers. When the number of selected principal components was varied, the highest test among the SVMs of various kernels and parameters was slightly higher than that of the LDA in one‐loop leave‐one‐case‐out resampling. However, no SVM with fixed architecture consistently performed better than the LDA in the range of principal components selected. This study demonstrated that the authors’ proposed segmentation and feature extraction techniques are promising for classifying lung nodules on CT images.
Characteristics of Gafchromic® XR‐RV2 radiochromic film
Authors: Blair Andrew , Meyer Juergen
Published: June 2009

Gafchromic® XR‐RV2 is a revised version of the obsolete Gafchromic® XR‐R‐type radiochromic film. This article investigates the dose response, energy response, postexposure growth, and polarizing effects of this film after exposure to ionizing radiation in the diagnostic energy range. The effect of bit depth on scanning was also investigated. Films were scanned using an Epson Expression 10000XL document scanner or an X‐Rite model 301 spot densitometer. Color channel analysis was performed. The film showed usable response in the air kerma range of 1–1000 cGy, although by 1500 cGy the film appeared saturated when using the red color channel on a document scanner. The film response varied by 11% between 60 and 96 kVp and 3.5% between 96 and 125 kVp for doses above 1 Gy. Postexposure growth was found to be approximately logarithmic and fairly stable after 24 h. Films stored under office lighting exhibited around twice the density growth compared with film stored in a dark environment. The film showed strong orientation dependence when scanned using a polarized light source. A 48 bit scan provided no increase in sensitivity over 24 bits. Gafchromic XR‐RV2 film is a radiochromic film ideally suited for measurement of wide dose ranges at diagnostic energies. The energy dependence of this film limits its accuracy for dosimetry of unknown energy beams. For the document scanners used in this study a 24 bit scan was more than sufficient compared to a 48 bit scan. This is likely to be the case for most document scanners where electrical noise prevents higher bit depths from increasing the sensitivity of measurements.