bluuebunny/crossref_metadata_2025 huggingface dataset:
The low‐FODMAP diet in the management of functional dyspepsia in East and Southeast Asia
Authors: Tan Victoria P
Published: February 2017

Functional dyspepsia (FD) is a common disorder in East and Southeast Asia where subjects experience post prandial fullness/bloating, early satiety, belching, epigastric pain, and/or burning. A subset of patients with FD experience triggers exclusively related to meals, defined as the post prandial distress syndrome in the Rome IV guidelines. There is significant overlap of symptoms and implicated pathogenic factors with another common functional gastrointestinal disorder, irritable bowel syndrome (IBS) and in fact, a significant proportion of subjects have FD/IBS overlap. The introduction of the low‐FODMAP diet has changed the paradigm of treatment for IBS. Like IBS, dietary management appears to be important to patients with FD and clinicians treating the condition. This review aims to examine the current role of diet in the management of FD in East and Southeast Asia, with an exploration of the likely efficacy and mechanisms of action of the low‐FODMAP diet in this region.
When the low FODMAP diet does not work
Authors: Halmos Emma P
Published: February 2017

Irritable bowel syndrome (IBS) is heterogeneous. Patients need proper assessment and explanation of IBS pathophysiology and appropriate therapies. A low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet effectively reduces symptoms in 75% of patients. Best treatment for those nonresponsive will depend on the pathophysiological basis for symptom genesis, with the following possible abnormalities: (i) Visceral hypersensitivity and/or enhanced gut‐brain communication: a low FODMAP diet is mainly targeted for this patient group. A dietitian may also recommend antispasmodic agents, including peppermint oil. Another dietary treatment is a low food chemical diet, although this diet is often extremely limited, and therefore, not suited for some populations. Psychological therapies are also clinically beneficial. (ii) Altered motility: in patients with fast transit, a dietitian may recommend a reduction in all FODMAPs or targeted monosaccharides and disaccharides, which are more osmotic in nature. If not effective, patients may benefit from psyllium, which has an exceptional water‐holding capacity aimed to promote more formed stools. Patients with slow or uncoordinated transit are often more difficult to treat. Dietary interventions have some success and usually comprise a combination of adequate fiber and fluid, osmotic laxatives, and stimulating agents such as caffeine, senna, and exercise. (iii) Altered microbiome: supplementary probiotics and prebiotics have weak evidence of efficacy with some notable exceptions. A dietitian may trial supplementary Bifidobacterium infantis or oligosaccharides, usually as an adjunct therapy. Guidance from a dietitian will encompass dietary methods to treat IBS but additionally identify where dietary treatment is not indicated to ensure that diet is correctly used and patients are not nutritionally or psychologically compromised.
Nursing home staff members' subjective frames of reference on residents' achievement of ego integrity: A Q‐methodology study
Authors: Lim Sun‐Young , Chang Sung‐Ok
Published: February 2017

Aim

To discover the structure of the frames of reference for nursing home staff members' subjective judgment of residents' achievement of ego integrity.

Methods

Q‐methodology was applied. Twenty‐eight staff members who were working in a nursing home sorted 34 Q‐statements into the shape of a normal distribution.

Results

A centroid factor analysis and varimax rotation, using the PQ‐method program, revealed four factors: identifying clues to residents' positive acceptance of their whole life span, identifying residents' ways of enjoying their current life, referencing residents' attitudes and competencies toward harmonious relationships, and identifying residents' integrated efforts to establish self‐esteem.

Conclusion

These subjective frames of reference need to be investigated in order to improve the relationships with nursing home residents and their quality of life. Consequently, the fundamental monitoring tools to help staff members make subjective judgments can be formed.
Clinical nursing instructors' perceived challenges in clinical teaching
Authors: Yang Cheng‐I , Chao Shu‐Yuan
Published: February 2017

Aim

The purpose of this qualitative study was to explore the challenges in clinical teaching that are encountered by clinical instructors and to foster the relevant training.

Methods

Focus group methodology was used. The participants were 54 clinical nursing instructors who were recruited from middle Taiwan and participated in one of five focus groups of 2–3 h each. The data transcripts were analyzed by using qualitative content analysis.

Results

Five challenges emerged: (i) teaching outside one's area of expertise; (ii) building cooperative relationships with the clinical staff; (iii) the unit's use of students as nursing staff; (iv) inappropriate clinical practices by the clinical staff; and (v) clinical staff members' negative comments toward the students. These challenges revealed clinical nursing instructors' difficulties in balancing clinical teaching quality and their relationships with the clinical staff members.

Conclusion

The identified challenges reflect the need to support clinical instructors and assist them to prepare for their role through training programs or policy changes.
KREEP basalt petrogenesis: Insights from 15434,181
Authors: Cronberger Karl , Neal Clive R.
Published: February 2017

Returned lunar KREEP basalts originated through impact processes or endogenous melting of the lunar interior. Various methods have been used to distinguish between these two origins, with varying degrees of success. Apollo 15 KREEP basalts are generally considered to be endogenous melts of the lunar interior. For example, sample 15434,181 is reported to have formed by a two‐stage cooling process, with large orthopyroxene (Opx) phenocrysts forming first and eventually cocrystalizing with smaller plagioclase crystals. However, major and trace element analyses of Opx and plagioclase coupled with calculated equilibrium liquids are inconsistent with the large orthopyroxenes being a phenocryst phase. Equilibrium liquid rare earth element (REE) profiles are enriched relative to the whole rock (WR) composition, inconsistent with Opx being an early crystallizing phase, and these are distinct from the plagioclase REE equilibrium liquids. Fractional crystallization modeling using the Opx equilibrium liquids as a parental composition cannot reproduce the WR values even with crystallization of late‐stage phosphates and zircon. This work concludes that instead of being a phenocryst phase, the large Opx crystals are actually xenocrysts that were subsequently affected by pyroxene overgrowths that formed intergrowths with cocrystallizing plagioclase.
The optimal blood glucose level for critically ill adult patients
Authors: Lv Shaoning , Ross Paul , Tori Kathleen
Published: February 2017

Background

Glycaemic control is recognized as one of the important aspects in managing critically ill patients. Both hyperglycaemia and hypoglycaemia independently increase the risk of patient mortality. Hence, the identification of optimal glycaemic control is of paramount importance in the management of critically ill patients.

Aims and objectives

The aim of this literature review is to examine the current status of glycaemic control in critically ill adult patients. This literature review will focus on randomized controlled trials comparing intensive insulin therapy to conventional insulin therapy, with an objective to identify optimal blood glucose level targets for critically ill adult patients.

Design and methods

A literature review was conducted to identify large randomized controlled trials for the optimal targeted blood glucose level for critically ill adult patients published since 2000. A total of eight studies fulfilled the selection criteria of this review.

Results

With current human and technology resources, the results of the studies support commencing glycaemic control once the blood glucose level of critically ill patients reaches 10 mmol/L and maintaining this level between 8 mmol/L and 10 mmol/L.

Conclusion

This literature review provides a recommendation for targeting the optimal blood glucose level for critically ill patients within moderate blood glucose level target range (8–10 mmol/L). The need for uniformed glucometrics for unbiased reporting and further research for optimal blood glucose target is required, especially in light of new technological advancements in closed‐loop insulin delivery and monitoring devices.

Relevance to clinical practice

This literature review has revealed a need to call for consensus in the measurement and reporting of glycaemic control using standardized glucometrics.
A global Fine‐Root Ecology Database to address below‐ground challenges in plant ecology
Authors: Iversen Colleen M. , McCormack M. Luke , Powell A. Shafer , Blackwood Christopher B. , Freschet Grégoire T. , Kattge Jens , Roumet Catherine , Stover Daniel B. , Soudzilovskaia Nadejda A. , Valverde‐Barrantes Oscar J. , van Bodegom Peter M. , Violle Cyrille
Published: February 2017

Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. While fine roots play an important role in ecosystem functioning, fine‐root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine‐root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine‐root trait database, and introduces the Fine‐Root Ecology Database (FRED, http://roots.ornl.gov) which so far includes > 70 000 observations encompassing a broad range of root traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below‐ground plant ecology. For example, FRED facilitates the quantification of variation in fine‐root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. Continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine‐root traits across space and time.
Surface ECG and Fluoroscopy are Not Predictive of Right Ventricular Septal Lead Position Compared to Cardiac CT
Authors: ROWE MATTHEW K. , MOORE PETER , PRATAP JIT , COUCHER JOHN , GOULD PAUL A. , KAYE GERALD C.
Published: February 2017

Background

Controversy exists regarding the optimal lead position for chronic right ventricular (RV) pacing. Placing a lead at the RV septum relies upon fluoroscopy assisted by a surface 12‐lead electrocardiogram (ECG). We compared the postimplant lead position determined by ECG‐gated multidetector contrast‐enhanced computed tomography (MDCT) with the position derived from the surface 12‐lead ECG.

Methods

Eighteen patients with permanent RV leads were prospectively enrolled. Leads were placed in the RV septum (RVS) in 10 and the RV apex (RVA) in eight using fluoroscopy with anteroposterior and left anterior oblique 30° views. All patients underwent MDCT imaging and paced ECG analysis. ECG criteria were: QRS duration; QRS axis; positive or negative net QRS amplitude in leads I, aVL, V1, and V6; presence of notching in the inferior leads; and transition point in precordial leads at or after V4.

Results

Of the 10 leads implanted in the RVS, computed tomography (CT) imaging revealed seven to be at the anterior RV wall, two at the anteroseptal junction, and one in the true septum. For the eight RVA leads, four were anterior, two septal, and two anteroseptal. All leads implanted in the RVS met at least one ECG criteria (median 3, range 1–6). However, no criteria were specific for septal position as judged by MDCT. Mean QRS duration was 160 ± 24 ms in the RVS group compared with 168 ± 14 ms for RVA pacing (P = 0.38).

Conclusions

We conclude that the surface ECG is not sufficiently accurate to determine RV septal lead tip position compared to cardiac CT.
Clinical Characteristics and Outcome of Patients with Situational Syncope Compared to Patients with Vasovagal Syncope
Authors: WENZKE KEVIN E. , WALSH KATHLEEN E. , KALSCHEUR MATTHEW , WASMUND STEPHEN L. , PAGE RICHARD L. , BRIGNOLE MICHELE , HAMDAN MOHAMED H.
Published: February 2017

Backgrounds

The purpose of the study was to assess the clinical outcome of patients with situational syncope (SS) compared to patients with vasovagal syncope (VVS).

Methods

We assessed the prevalence, patients’ characteristics, and outcome of consecutive patients with SS and VVS who presented to the Faint and Fall Clinic (University of Wisconsin) between January 2013 and December 2015.

Results

SS was found in 55/1,401 (4.0%) syncope patients with follow‐up data available in 47 patients: defecation (n = 16), micturition (n = 15), cough (n = 10), swallow (n = 3), laughter (n = 1), sneeze (n = 1), and cough plus laughter (n = 1). Over the same time period, 252/1,401 patients (18%) were diagnosed with VVS with follow‐up data available in 171 patients. Compared with VVS patients, SS patients were older, more likely to be male, had a higher prevalence of hypertension, had an absence of prodromes, and experienced more injuries at the time of syncope (P = 0.01 for all). During a mean follow‐up duration of 15.4 ± 9.1 months, syncope recurred in 5/47 (10.6%) patients with SS and 16/171 (9.4%) patients with VVS. The recurrence rates at 1 year and 2 years were 20% (95% SE ± 13) and 40% (95% SE ± 20) for the SS group, and 23% (95% SE ± 13) and 43% (95% SE ± 20) for the VVS group (P = 0.6). No patient died.

Conclusions

We have shown in a large cohort of consecutive patients with syncope that SS is a relatively infrequent form of reflex syncope with different clinical characteristics but similar recurrence rate to VVS.
Magnesium sulfate in pediatric anesthesia: the Super Adjuvant
Authors: Eizaga Rebollar Ramón , García Palacios María V. , Morales Guerrero Javier , Torres Luis M.
Published: February 2017

Magnesium is an essential chemical element in all organisms, intervening in most cellular enzymatic reactions; thus, its importance in homeostasis and as a therapeutic tool in highly challenging patients such as pediatrics. The primary purpose of this paper was to review the role of magnesium sulfate as an adjuvant drug in pediatric anesthesia. This compound already has the scientific backing in certain aspects such as analgesia or muscle relaxation, but only theoretical or empirical backing in others such as organ protection or inflammation, where it seems to be promising. The multitude of potential applications in pediatric anesthesia, its high safety, and low cost make magnesium sulfate could be considered a Super Adjuvant.
Perioperative considerations for the food‐allergic pediatric patient
Authors: Fernandez Patrick G. , Mikhael Marco
Published: February 2017

Patients with a history of food allergy and food intolerance are common in the pediatric population and are encountered frequently in the perioperative setting by pediatric anesthesiologists. Perioperatively, food allergy can present on a spectrum ranging from minor acute urticaria to more severe hypovolemia and anaphylactic shock. Allergy to foods including fruits, fish, egg, soy, and peanut are most concerning for their potential to cross‐react with perioperative medications. There is little in the anesthesia literature that focuses on the perioperative management of children with food allergies. This educational review will provide a brief overview of classic immunoglobulin E (IgE)‐mediated food allergies, less common non‐IgE food allergies, and present perioperative considerations for these patients. An audio summary of this topic is included as Supplementary Audio S1.
Anxiety and depression in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME): Examining the incidence of health anxiety in CFS/ME
Authors: Daniels Jo , Brigden Amberly , Kacorova Adela
Published: February 2017

Objectives

There is a lack of research examining the incidence of health anxiety in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), despite this being an important research area with potentially significant clinical implications. This preliminary study aimed to determine the incidence of anxiety and depression, more specifically health anxiety, in a sample of CFS/ME patients over a 3‐month period.

Design

The research was a cross‐sectional questionnaire‐based study, using a consecutive sample of patients who were assessed in a CFS/ME service.

Method

Data were taken from the Short Health Anxiety Inventory and the Hospital Anxiety and Depression Scale to identify incidence of anxiety, depression, and health anxiety.

Results

Data were collected from 45 CFS/ME patients over the sampling period. Thirty‐one patients (68.9%) scored above the normal range but within the subclinical range of health anxiety, and 19 patients (42.2%) scored within the clinically significant health anxiety range. Anxiety and depression were common, with prevalence rates of 42.2% and 33.3% respectively, which is comparable to data found in a recent large‐scale trial.

Conclusions

Health anxiety in CFS/ME patients is likely to be common and warrants further investigation to provide a better insight into how this may influence treatment and symptom management.

Practitioner points

Anxiety and depression were common in a sample of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) patients, with a high proportion meeting criteria for severe health anxiety.

While CFS/ME and health anxiety are distinct and separate conditions, it is unsurprising that patients with CFS/ME, who commonly report feeling ‘delegitimized’, may experience high levels of anxiety relating to their physical symptoms.

Clinicians should consider screening for health anxiety due to the possible clinical implications for treatment; mutual maintenance may negatively influence treatment success in a complex condition such as CFS/ME.

Health anxiety has been found to be common across other chronic medical conditions but has been shown to be effectively treated with appropriately tailored interventions.
Neo‐pragmatism, Representationalism and the Emotions
Authors: Gert Joshua
Published: February 2017

This paper offers a neo‐pragmatist account of the representational character of the emotions, for those emotions that have such a character. Put most generally, neo‐pragmatism is the view that language should not be conceived primarily in terms of a robust relation of reference to or representation of antecedently given objects and properties. Rather, we should view it as a social practice that lets us do various quite different sorts of things. One of those things might be called ‘assessing representational accuracy’, but this need not be thought of in terms of a metaphysically heavyweight relation. In applying neo‐pragmatist techniques to the domain of the emotions, the result will be an alternative to currently popular accounts that individuate emotions partly in terms of what they represent. This alternative continues to allow us to use representational language in connection withsomeemotions. And it also helps to explain the awkwardness of representational talk in connection withotheremotions: an awkwardness that was always a liability of monolithic representationalist views.
Finely Resolved On‐Road PM2.5 and Estimated Premature Mortality in Central North Carolina
Authors: Chang Shih Ying , Vizuete William , Serre Marc , Vennam Lakshmi Pradeepa , Omary Mohammad , Isakov Vlad , Breen Michael , Arunachalam Saravanan
Published: February 2017

To quantify the on‐road PM2.5‐related premature mortality at a national scale, previous approaches to estimate concentrations at a 12‐km × 12‐km or larger grid cell resolution may not fully characterize concentration hotspots that occur near roadways and thus the areas of highest risk. Spatially resolved concentration estimates from on‐road emissions to capture these hotspots may improve characterization of the associated risk, but are rarely used for estimating premature mortality. In this study, we compared the on‐road PM2.5‐related premature mortality in central North Carolina with two different concentration estimation approaches—(i) using the Community Multiscale Air Quality (CMAQ) model to model concentration at a coarser resolution of a 36‐km × 36‐km grid resolution, and (ii) using a hybrid of a Gaussian dispersion model, CMAQ, and a space–time interpolation technique to provide annual average PM2.5 concentrations at a Census‐block level (∼105,000 Census blocks). The hybrid modeling approach estimated 24% more on‐road PM2.5‐related premature mortality than CMAQ. The major difference is from the primary on‐road PM2.5 where the hybrid approach estimated 2.5 times more primary on‐road PM2.5‐related premature mortality than CMAQ due to predicted exposure hotspots near roadways that coincide with high population areas. The results show that 72% of primary on‐road PM2.5 premature mortality occurs within 1,000 m from roadways where 50% of the total population resides, highlighting the importance to characterize near‐road primary PM2.5 and suggesting that previous studies may have underestimated premature mortality due to PM2.5 from traffic‐related emissions.
Stability, Steady‐State Bifurcations, and Turing Patterns in a Predator–Prey Model with Herd Behavior and Prey‐taxis
Authors: Song Yongli , Tang Xiaosong
Published: February 2017

In this paper, we consider a predator–prey model with herd behavior and prey‐taxis subject to the homogeneous Neumann boundary condition. First, by analyzing the characteristic equation, the local stability of the positive equilibrium is discussed. Then, choosing prey‐tactic sensitivity coefficient as the bifurcation parameter, we obtain a branch of nonconstant solutions bifurcating from the positive equilibrium by an abstract bifurcation theory, and find the stable bifurcating solutions near the bifurcation point under suitable conditions. We have shown that prey‐taxis can destabilize the uniform equilibrium and yields the occurrence of spatial patterns. Furthermore, some numerical simulations to illustrate the theoretical analysis are also carried out, Turing patterns such as spots pattern, spots–strip pattern, strip pattern, stable nonconstant steady‐state solutions, and spatially inhomogeneous periodic solutions are obtained, which also expand our theoretical results.
A Reduced Order Modeling Methodology for Steam Turbine Clearance Control Design
Authors: Biyik Emrah , D'Amato Fernando J. , Subramaniyan Arun , Sun Changjie
Published: February 2017

Finite element models (FEMs) are extensively used in the design optimization of utility scale steam turbines. As an example, by simulating multiple startup scenarios of steam power plants, engineers can obtain turbine designs that minimize material utilization, and at the same time, avoid the damaging effects of large thermal stresses or rubs between rotating and stationary parts. Unfortunately, FEMs are computationally expensive and only a limited amount of simulations can be afforded to get the final design. For this reason, numerous model reduction techniques have been developed to reduce the size of the original model without a significant loss of accuracy. When the models are nonlinear, as is the case for steam turbine FEMs, model reduction techniques are relatively scarce and their effectiveness becomes application dependent. Although there is an abundant literature on model reduction for nonlinear systems, many of these techniques become impractical when applied to a realistic industrial problem. This paper focuses on a class of nonlinear FEM characteristic of thermo-elastic problems with large temperature excursions. A brief overview of popular model reduction techniques is presented along with a detailed description of the computational challenges faced when applying them to a realistic problem. The main contribution of this work is a set of modifications to existing methods to increase their computational efficiency. The methodology is demonstrated on a steam turbine model, achieving a model size reduction by four orders of magnitude with only 4% loss of accuracy with respect to the full order FEMs.
Performance Measurements of Gas Bearings With High Damping Structures of Polymer and Bump Foil Via Electric Motor Driving Tests and One Degree-of-Freedom Shaker Dynamic Loading Tests
Authors: Sim Kyuho , Park Jisu
Published: February 2017

This paper presents comprehensive test measurements for gas journal bearings with damping structures of a bump foil layer and/or a polymer layer. A one-pad top foil forms the bearing surface, under which the bearing structure and a bearing housing are located. Test bearings include gas foil bearings (GFBs), gas polymer bearings (GPBs), and gas foil-polymer bearings (GFPBs). In addition, three metal shims were employed to create wedge effects in the GFPBs. First, static load-deflection tests of test bearings estimate the radial assembly clearance. Second, shake dynamic loading tests identify frequency-dependent dynamic characteristics. An electromagnetic shaker provides flat bearing specimens with one degree-of-freedom (1DOF) vertical dynamic loading. GFPB was measured to exhibit a higher structural damping and lower stiffness than GFB. Lastly, the electric motor driving tests examine the rotordynamic stability performance. A permanent magnet (PM) synchronous motor drives a PM rotor supported on a pair of test journal bearings. As a result, the GFPBs with mechanical preloads enhanced the rotordynamic performance with no subsynchronous motions up to the maximum rotor speed of 88 krpm, and the bearing friction characteristics as well. Furthermore, they showed comparable rotordynamic performance to three-pad GFBs from a past literature, even with larger bearing clearances and small mechanical preloads.
Transient Analysis of Nonuniform Heat Input Propagation Through a Heat Sink Base
Authors: Sudhakar Srivathsan , Weibel Justin A.
Published: February 2017

For thermal management architectures wherein the heat sink is embedded close to a dynamic heat source, nonuniformities may propagate through the heat sink base to the coolant. Available transient models predict the effective heat spreading resistance to calculate chip temperature rise, or simplify to a representative axisymmetric geometry. The coolant-side temperature response is seldom considered, despite the potential influence on flow distribution and stability in two-phase microchannel heat sinks. This study solves three-dimensional transient heat conduction in a Cartesian chip-on-substrate geometry to predict spatial and temporal variations of temperature on the coolant side. The solution for the unit step response of the three-dimensional system is extended to any arbitrary temporal heat input using Duhamel's method. For time-periodic heat inputs, the steady-periodic solution is calculated using the method of complex temperature. As an example case, the solution of the coolant-side temperature response in the presence of different transient heat inputs from multiple heat sources is demonstrated. To represent a case where the thermal spreading from a heat source is localized, the problem is simplified to a single heat source at the center of the domain. Metrics are developed to quantify the degree of spatial and temporal nonuniformity in the coolant-side temperature profiles. These nonuniformities are mapped as a function of nondimensional geometric parameters and boundary conditions. Several case studies are presented to demonstrate the utility of such maps.
Effect of Packaging Architecture on the Optical and Thermal Performances of High-Power Light Emitting Diodes
Authors: Law Thong Kok , Lim Fannon , Li Yun , Puan XuePeng , Sng G. K. E. , Ronnie Teo J. W.
Published: February 2017

The phosphor and die bonding configuration affect the optical efficiency and thermal performance in phosphor-coated white light emitting diodes (LEDs). In this paper, light emission studies reveal that the chromaticity shift and light extraction losses depend on the uniformity of phosphor particles deposited over the LED surface. A nonuniform and sparse phosphor layer affects the correlated color temperature (CCT) and the spectral Y–B ratio due to the disproportionate contribution of light emission between the LED device and the phosphor layer. Furthermore, the Y–B ratio was observed to reduce with temperature due to higher Stoke's energy and light extraction losses in the phosphor layer. As a result, the Y–B ratio exhibits an inverse relationship with the package's thermal resistance as a function of temperature. On the other hand, the thermal performance of a LED package is dependent on the die-bonding configurations (conventional and flip-chip). Due to the improved heat dissipation capabilities in flip-chip bonding, the temperature rise and thermal resistance of the package were observed to reduce with temperature. By alleviating the heat accumulation in the package, more stable colorimetric properties such as CCT and Y–B ratio can be achieved.
Clinical experience with two frameless stereotactic radiosurgery (fSRS) systems using optical surface imaging for motion monitoring
Authors: Li Guang , Ballangrud Ase , Chan Maria , Ma Ruimei , Beal Kathryn , Yamada Yoshiya , Chan Timothy , Lee James , Parhar Preeti , Mechalakos James , Hunt Margie
Published: February 2017

The purpose of this study was to compare two clinical immobilization systems for intracranial frameless stereotactic radiosurgery (fSRS) under the same clinical procedure using cone‐beam computed tomography (CBCT) for setup and video‐based optical surface imaging (OSI) for initial head alignment and intrafractional motion monitoring. A previously established fSRS procedure was applied using two intracranial immobilization systems: PinPoint system (head mold and mouthpiece) and Freedom system (head mold and open face mask). The CBCT was used for patient setup with four degrees of freedom (4DOF), while OSI was used for 6DOF alignment prior to CBCT, post‐CBCT setup verification at all treatment couch angles (zero and nonzero), and intrafractional motion monitoring. Quantitative comparison of the two systems includes residual head rotation, head restriction capacity, and patient setup time in 25 patients (29 lesions) using PinPoint and 8 patients (29 fractions) using Freedom. The maximum possible motion was assessed in nine volunteers with deliberate, forced movement in Freedom system. A consensus‐based comparison of patient comfort level and clinical ease of use is reported. Using OSI‐guided corrections, the maximum residual rotations in all directions were for PinPoint and for Freedom. The time spent performing rotation corrections was min by moving the patient with PinPoint and min by adjusting Freedom couch extension. After CBCT, the OSI–CBCT discrepancy due to different anatomic landmarks for alignment was using PinPoint and using Freedom. Similar results were obtained for setup verification at couch angles () and for motion restriction: in PinPoint and in Freedom. The maximum range of forced head motion was using Freedom. Both intracranial fSRS immobilization systems can restrict head motion within 1.5 mm during treatment as monitored by OSI. Setting a motion threshold for beam‐hold ensures that head motion is constrained within the treatment margin during beam‐on periods. The capability of 6D setup is useful to improve treatment accuracy. Patient comfort and clinical workflow should play a substantial role in system selection, and Freedom system outperforms PinPoint system in these two aspects.

PACS number: 87.53.Ly, 87.55.D‐, 87.57.Q‐, 87.6s.L‐, 87.85.gi
Investigation of the clinical performance of a novel solid‐state diagnostic dosimeter
Authors: Tse Jason , McLean Donald
Published: February 2017

This study investigated the clinical performance of a novel solid‐state diagnostic dosimeter, the RaySafe Xi transparent detector, by comparing its performance to a reference‐class ionization chamber. Firstly a comparison of dosimeter response “free‐in‐air” with standard beam qualities was made, followed by an investigation into its relative transparency in an X‐ray field and angular sensitivity dependence. The second part of the study looked at the overall performance of the transparent detector under scatter conditions with a number of beam qualities, including standard beam and those hardened by copper (Cu) filtration of thickness up to 0.9 mm, as would be encountered in the equipment testing of fluoroscopy systems. Overall, the transparent detector has demonstrated equivalent measurement properties to the ionization chamber under standard conditions and provided similar X‐ray attenuation as reflected by the nearly identical radiographic parameters selected for both dosimeters by the automatic dose rate control (ADRC) system. Yet, it also possessed an asymmetric angular response which respectively under‐ and overestimated the dose contribution from the rear and lateral directions by the same amount of 50%. The transparent detector provided comparable dose reading of to the ionization chamber with standard beam qualities and backscatter radiation present. These results were in good agreement with those of free‐in‐air measurement, indicating that the angular under‐ and overresponse might potentially compensate one another for accurate measurement. However, for identical Cu filtered beam qualities and setups, the transparent detector on average overresponded by 5.4% across the useful tube voltage range. In conclusion, the transparent detector, with its novel design, is essentially equivalent, within a 5% tolerance, to an ionization chamber, except in situations where beams hardened with Cu filtration are used with backscatter radiation present requiring larger uncertainty error estimations.

PACS numbers: 87.57 uq, 87.59.C‐, 87.59.Dj
Practical considerations in the selection of seed strength for prostate implants
Authors: Elliott Sarah L , Beaufort Catherine L. , Millar Jeremy L.
Published: February 2017

There are advantages in using lower numbers of higher activity seeds for prostate seed implants. This work investigated the use of higher strength seeds for our manually optimized prostate implants. Following a planning study using a range of seeds strengths between 0.4 U and 0.7 U, a series of patients were implanted using seeds of strength . Twenty consecutive patients were selected for this study; ten patients were implanted with 0.4 U seeds and the next ten patients implanted with 0.7 U seeds. Postimplant dosimetry for the target volume, urethra, and rectal wall was compared between the two groups. Our data showed a small and insignificant decrease in the total theatre time when implanting seeds of higher strength. The mean number of seeds required per implant decreased by over 30% for the 0.7 U implants, and the mean number of needles decreased by eight needles. The mean D90 (%) was marginally lower for the 0.7 U group, and spread over a wider range of values. Doses to the rectal wall were slightly higher for the 0.7 U group. At six years postimplant, the symptom scores for urinary and rectal toxicity and erectile function were similar to those reported before brachytherapy, with little differences between the 0.4 U and 0.7 U groups. Our experiences and practical advice in the selection of seed strength for prostate implants are reported in this paper.

PACS number: 87.53.Jw
Automated population‐based planning for whole brain radiation therapy
Authors: Schreibmann Eduard , Fox Tim , Curran Walter , Shu Hui‐Kuo , Crocker Ian
Published: February 2017

Treatment planning for whole‐brain radiation treatment is technically a simple process, but in practice it takes valuable clinical time of repetitive and tedious tasks. This report presents a method that automatically segments the relevant target and normal tissues, and creates a treatment plan in only a few minutes after patient simulation. Segmentation of target and critical structures is performed automatically through morphological operations on the soft tissue and was validated by comparing with manual clinical segmentation using the Dice coefficient and Hausdorff distance. The treatment plan is generated by searching a database of previous cases for patients with similar anatomy. In this search, each database case is ranked in terms of similarity using a customized metric designed for sensitivity by including only geometrical changes that affect the dose distribution. The database case with the best match is automatically modified to replace relevant patient info and isocenter position while maintaining original beam and MLC settings. Fifteen patients with marginally acceptable treatment plans were used to validate the method. In each of these cases the anatomy was accurately segmented, but the beams and MLC settings led to a suboptimal treatment plan by either underdosing the brain or excessively irradiating critical normal tissues. For each case, the anatomy was automatically segmented with the proposed method, and the automated and manual segmentations were then compared. The mean Dice coefficient was 0.97, with a standard deviation of 0.008 for the brain, for the eyes, and for the lens. The mean Euclidian distance was for the brain, for the eye, and for the lens. Each case was then subsequently matched against a database of 70 validated treatment plans and the best matching plan (termed autoplanned), was compared retrospectively with the clinical plans in terms of brain coverage and maximum doses to critical structures. Maximum doses were reduced by a maximum of 8.37 Gy for the left eye (mean 2.08), 11.67 for the right eye (1.90) and, respectively, 25.44 (5.59) for the left lens and 24.40 (4.85) for the right lens. Time to generate the autoplan, including the segmentation, was . Automated database‐ based matching is an alternative to classical treatment planning that improves quality while providing a cost‐effective solution to planning through modifying previous validated plans to match a current patient's anatomy.

PACS number: 87.55.D, 87.55.tg, 87.57.nm
Computed tomography dosimetry with high‐resolution detectors commonly used in radiotherapy — an energy dependence study
Authors: Liebmann Mario , Poppe Bjoern , von Boetticher Heiner
Published: February 2017

New methods of dosimetry in computed tomography (CT) X‐ray fields require the use of high‐resolution detectors instead of pencil‐type ionization chambers typically used for CT dose index (CTDI) measurements. This paper presents a study on the suitability of a wide range of ionization chambers, diodes, and a two‐dimensional detector array, used primarily in radiation therapy, for CT and cone‐beam CT dosimetry. Specifically, the energy dependence of these detectors from 50 kVp up to 125 kVp is reported. All measurements were performed in reference to a calibrated diode for use in this energy region. The radiation quality correction factors provided by the manufacturer were used, depending on the measured half‐value layer (HVL) for the particular X‐ray beam. Our study demonstrated the general usability of thimble ionization chambers. These thimble ionization chambers showed a maximum variation in energy response of 5%. Ionization chambers with even smaller sensitive volume, and which exhibit similar variation in energy dependence, can be used if higher spatial resolution is required. Furthermore, the investigated detectors are better suited for dosimetry at CT and CBCT units than conventional large volume or flat detectors, due to their rotational symmetry. Nevertheless, a flat detector can be used for certain measurement tasks, such as the acquisition of percent depth‐dose curves or beam profiles for nonrotating beams, which are important for beam characterization.

PACS numbers: 87.57.uq, 87.56.Da, 87.57.Q‐
Reducing radiation risks to staff for patients with permanently implanted radioactive sources requiring unrelated surgery
Authors: Basran Parminder S. , Baxter Patricia , Beckham Wayne A.
Published: February 2017

Permanent implant of sealed radioactive sources is an effective technique for treating cancer. Typically, the radioactive sources are implanted in and near the disease, depositing radiation absorbed dose locally over several months. There may be instances where these patients must undergo unrelated surgical procedures when the radioactive material remains active enough to pose risks. This work explores these risks, discusses strategies to mitigate those risks, and describes a case study for a permanent iodine‐125 (I‐125) prostate brachytherapy implant patient who developed colorectal cancer and required surgery six months after brachytherapy. The first consideration is identifying the radiological risk to the patient and staff before, during, and after the surgical procedure. The second is identifying the risk the surgical procedure may have on the efficacy of the brachytherapy implant. Finally, there are considerations for controlling the radioactive substances from a regulatory perspective. After these risks are defined, strategies to mitigate those risks are considered. We summarize this experience with some guidelines: If the surgical procedure is near (e.g., within 5–10 cm of) the implant; and, the surgical intervention may dislodge sources enough to compromise treatment or introduces radiation safety risks; and, the radioactivity has not sufficiently decayed to background levels; and, the surgery cannot be postponed, then a detailed analysis of risk is advised.

PACS numbers: 87.53Bn, 87.53Jw, 87.55.N, 87.56.bg
Enhanced dynamic wedge output factors for Varian 2300CD and the case for a reference database
Authors: Njeh Christopher F.
Published: February 2017

Dose inhomogeneity in treatment planning can be compensated using physical wedges. Enhanced dynamic wedges (EDW) were introduced by Varian to overcome some of the shortcomings of physical wedges. The objectives of this study were to measure EDW output factors for 6 MV and 20 MV photon energies for a Varian 2300CD. Secondly, to review the literature in terms of published enhanced dynamic wedge output factors (EDWOF) for different Varian models and thereby add credence to the case of the validity of reference databases. The enhanced dynamic wedge output factors were measured for the Varian 2300CD for both 6 MV and 20 MV photon energies. Twelve papers with published EDWOF for different Varian linac models were found in the literature. Comparing our results with the published mean, we found an excellent agreement for 6 MV EDWOF, with the percentage differences ranging from 0.01% to 0.57%, with a mean of 0.03%. The coefficient of variation of published EDWOF ranged from 0.17% to 0.85% and 0.1% to 0.9% for the for 6 MV and 18 MV photon energies, respectively. This paper provides the first published EDWOF for 20 MV photon energy. In addition, we have provided the first compendium of EDWOFs for different Varian linac models. The consistency of value across models and institution provide further support that a standard dataset of basic photon and electron dosimetry could be established as a guide for future commissioning, beam modeling, and quality assurance purposes.

PACS numbers: 87.50, 87.55
Accuracy of dual‐energy computed tomography for the quantification of iodine in a soft tissue‐mimicking phantom
Authors: Li Jung‐Hui , Du Yeh‐Ming , Huang Hsuan‐Ming
Published: February 2017

The objective of this study was to evaluate the accuracy of dual‐energy CT (DECT) for quantifying iodine using a soft tissue‐mimicking phantom across various DECT acquisition parameters and dual‐source CT (DSCT) scanners. A phantom was constructed with plastic tubes containing soft tissue‐mimicking materials with known iodine concentrations (0–20 mg/mL). Experiments were performed on two DSCT scanners, one equipped with an integrated detector and the other with a conventional detector. DECT data were acquired using two DE modes (80 kV/Sn140 kV and 100 kV/Sn140 kV) with four pitch values (0.6, 0.8, 1.0, and 1.2). Images were reconstructed using a soft tissue kernel with and without beam hardening correction (BHC) for iodine. Using the dedicated DE software, iodine concentrations were measured and compared to true concentrations. We also investigated the effect of reducing gantry rotation time on the DECT‐based iodine measurement. At iodine concentrations higher than 10 mg/mL, the relative error in measured iodine concentration increased slightly. This error can be decreased by using the kernel with BHC, compared with the kernel without BHC. Both 80 kV/Sn140 kV and 100 kV/Sn140 kV modes could provide accurate quantification of iodine content. Increasing pitch value or reducing gantry rotation time had only a minor impact on the DECT‐based iodine measurement. The DSCT scanner, equipped with the new integrated detector, showed more accurate iodine quantification for all iodine concentrations higher than 10 mg/mL. An accurate quantification of iodine can be obtained using the second‐generation DSCT scanner in various DE modes with pitch values up to 1.2 and gantry rotation time down to 0.28 s. For iodine concentrations , using the new integrated detector and the kernel with BHC can improve the accuracy of DECT‐based iodine measurements.

PACS number: 87.57.Q‐
Development and clinical evaluation of a simple optical method to detect and measure patient external motion
Authors: Barbés Benigno , Azcona Juan Diego , Prieto Elena , de Foronda José Manuel , García Marina , Burguete Javier
Published: February 2017

A simple and independent system to detect and measure the position of a number of points in space was devised and implemented. Its application aimed to detect patient motion during radiotherapy treatments, alert of out‐of‐tolerances motion, and record the trajectories for subsequent studies. The system obtains the 3D position of points in space, through its projections in 2D images recorded by two cameras. It tracks black dots on a white sticker placed on the surface of the moving object. The system was tested with linear displacements of a phantom, circular trajectories of a rotating disk, oscillations of an in‐house phantom, and oscillations of a 4D phantom. It was also used to track 461 trajectories of points on the surface of patients during their radiotherapy treatments. Trajectories of several points were reproduced with accuracy better than 0.3 mm in the three spatial directions. The system was able to follow periodic motion with amplitudes lower than 0.5 mm, to follow trajectories of rotating points at speeds up to 11.5 cm/s, and to track accurately the motion of a respiratory phantom. The technique has been used to track the motion of patients during radiotherapy and to analyze that motion. The method is flexible. Its installation and calibration are simple and quick. It is easy to use and can be implemented at a very affordable price. Data collection does not involve any discomfort to the patient and does not delay the treatment, so the system can be used routinely in all treatments. It has an accuracy similar to that of other, more sophisticated, commercially available systems. It is suitable to implement a gating system or any other application requiring motion detection, such as 4D CT, MRI or PET.

PACS numbers: 87.55.N, 87.56.Da