bluuebunny/crossref_metadata_2025 huggingface dataset:
Depression, anxiety and health‐related quality of life amongst patients who are starting dialysis treatment
Authors: Rebollo Rubio Ana , Morales Asencio José Miguel , Eugenia Pons Raventos Ma
Published: February 2017

Background

Chronic kidney disease (CKD) has a severe impact on patients' health‐related quality of life (HRQL). The start of renal replacement therapy (RRT) significantly influences psychological, physical and social aspects of life.

Objectives

To analyse the HRQL and psychological status (anxiety and depression) at the start of RRT.

Methods

We undertook an observational descriptive cross‐sectional study. A total of 152 patients starting RRT were recruited for the study. HRQL was measured by the Kidney Disease and Quality of Life Short Form questionnaire. Levels of anxiety and depression were assessed by the Hospital Anxiety and Depression Scale questionnaire. Comorbidities and sociodemographic and clinical factors were also evaluated.

Findings

HRQL in patients with end‐stage kidney disease (ESKD) is significantly affected by the initiation of RRT in all respects. States of anxiety and depression were present in 26.6% and 27% of patients, respectively. These states are significantly related to the emotional component of the quality of life.

Conclusion

The initiation of RRT has a strong impact on HRQL in comparison with a reference population and with other stages of CKD. The early detection of an altered psychological state is important, as this condition should be treated from the first stages of the disease, as it can significantly affect the subsequent development of RRT and the patient's quality of life.
Insomnia management in prisons in England and Wales: a mixed‐methods study
Authors: Dewa Lindsay H. , Hassan Lamiece , Shaw Jenny J. , Senior Jane
Published: February 2017

Insomnia in prison is common; however, research is limited regarding the management strategies that prison establishments employ. To address this knowledge gap, we conducted a survey to identify how insomnia is detected, diagnosed and treated in adult prisons in England and Wales. Telephone interviews with a purposive sample of health‐care managers were then conducted. The survey was sent to all establishments holding adult prisoners, covering screening and assessment methods to detect insomnia; treatment options, both pharmacological and non‐pharmacological; the importance of insomnia as a treatable condition; and staff training available. Eighty‐four (73%) prisons completed the survey. Few had a stepped approach to insomnia management, as recommended by National Institute for Health and Care Excellence (NICE) guidelines. The most common treatments available were sleep hygiene education and medication, offered by 94 and 88% of respondents, respectively. Analysis of telephone interviews revealed four main themes: insomnia as a normal occurrence in prison; the problem of medication in prison; the negative impact of the prison environment; and effective management of insomnia in prison. The current findings suggest that logistical, ethical and security barriers and a lack of staff knowledge and training impact negatively on the management of insomnia in prison.
Cannabinoids as gastrointestinal anti‐inflammatory drugs
Authors: Fabisiak A. , Fichna J.
Published: February 2017

In this mini‐review, we focus on the potential of the endocannabinoid system as a target for novel therapies to treat gastrointestinal (GI) inflammation. We discuss the organization of the endocannabinoid signaling and present possible pharmacological sites in the endocannabinoid system. We also refer to recent clinical findings in the field. Finally, we point at the potential use of cannabinoids at low, non‐psychoactive doses to counteract non‐inflammatory pathological events in the GI tract, like chemotherapy‐induced diarrhea, as evidenced by Abalo et al. in the rat model.
The masks of Avh238
Authors: Kale Shiv D.
Published: February 2017

This article is a Commentary on Yang et al., 214: 361–375.
“Sky Full of Stars” Pattern: Dermoscopic Findings in a Desmoplastic Giant Congenital Melanocytic Nevus
Authors: Martín‐Carrasco Pablo , Bernabeu‐Wittel José , Dominguez‐Cruz Javier , Zulueta Dorado Teresa , Conejo‐Mir Sanchez Julian
Published: February 2017

Desmoplastic giant congenital melanocytic nevus (DGCN) is an uncommon variant of congenital nevus, presenting as a progressive induration and hypopigmentation of the lesion that occasionally causes hair loss and even total or partial disappearance of the nevus. A 6‐month‐old girl with a giant congenital melanocytic nevus that involved the entire posterior side of the right thigh was seen in our department. Nine months later, the peripheral area of the nevus presented as a marked induration with hypopigmentation. Dermoscopy demonstrated a reticular pattern exclusively located in the perifollicular areas, with a radial distribution from the follicular ostium that mimicked a “sky full of stars.” We report a case of DGCN, including a dermoscopic description of the findings noted in the indurated and hypopigmented areas that appear as a “sky full of stars” image.
Preventing the Use of Deadly Force: The Relationship between Police Agency Policies and Rates of Officer‐Involved Gun Deaths
Authors: Jennings Jay T. , Rubado Meghan E.
Published: February 2017

Killings of civilians by police officers have become a matter of intense public concern in the United States. High‐profile deaths, especially those of black citizens, have caused outrage and sparked the Black Lives Matter movement with calls for dramatic changes in how police agencies operate. However, little systematic research exists to answer questions about which policies should be ended or put in place to reduce these deaths. The authors leverage a large data set of gun deaths by police officers in the United States, combined with agency‐level policy data and community demographic data, to examine whether certain policies are associated with lower or higher rates of officer‐involved gun deaths. Findings show that one policy—the requirement that officers file a report when they point their guns at people but do not fire—is associated with significantly lower rates of gun deaths.
Commentary: Perception and Performance in Effective Policing
Authors: Villegas Jorge A.
Published: February 2017

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Policing and Race
Authors: Ward James D. , Menifield Charles E.
Published: February 2017

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A decision analytic model to guide early‐stage government regulatory action: Applications for synthetic biology
Authors: Trump Benjamin , Cummings Christopher , Kuzma Jennifer , Linkov Igor
Published: February 2017

Synthetic biology (SB) involves the alteration of living cells and biomolecules for specific purposes. Products developed using these approaches could have significant societal benefits, but also pose uncertain risks to human and environmental health. Policymakers currently face decisions regarding how stringently to regulate and monitor various SB applications. This is a complex task, in which policymakers must balance uncertain economic, political, social, and health‐related decision factors associated with SB use. We argue that formal decision analytical tools could serve as a method to integrate available evidence‐based information and expert judgment on the impacts associated with SB innovations, synthesize that information into quantitative indicators, and serve as the first step toward guiding governance of these emerging technologies. For this paper, we apply multi‐criteria decision analysis to a specific case of SB, a micro‐robot based on biological cells called “cyberplasm.” We use data from a Delphi study to assess cyberplasm governance options and demonstrate how such decision tools may be used for assessments of SB oversight.
Immune Class Regulation and Its Medical Significance Part II of a Report of a Workshop on Foundational Concepts of Immune Regulation
Authors: Bretscher P. A. , Corthay A. , Anderson C. C. , Dembic Z. , Havele C. , Nagy Z. A. , Øynebråten I.
Published: February 2017

We discussed different proposals for how the nature of the Th1/Th2 phenotype of an immune response is determined, and favoured one, the Threshold Hypothesis, as plausible and so useful as the basis for further discussions. The activation of a target CD4 T cell can be facilitated by helper CD4 T cells when the CD4 T cells interact via an antigen‐presenting cell. The Threshold Hypothesis states that tentative and robust antigen‐mediated CD4 T cell cooperation results in the target CD4 T cell, respectively giving rise, upon activation, to Th1 and Th2 cells. We primarily discussed four topics. We briefly discussed in the background section certain limitations of the Th1/Th2 paradigm in understanding immune class regulation, and the remarkable anti‐inflammatory properties of human IgG4 antibody. Secondly, we assessed the role of class II MHC molecules in determining the number of mature CD4 T cells and so affecting the Th1/Th2 phenotype of immune responses. We also discussed the controversial role of CD8 T cells in affecting the Th1/Th2 phenotype of responses to MHC and other antigens, and the potential role of their relative scarcity in neonates in biasing responses towards an antibody, Th2 mode. Lastly, we examined the regulation of the Th1/Th2 phenotype of both primary and ongoing immune responses in the context of the intriguing proposal that antigen initially generates different classes/subclasses of immunity and then selects, by a feedback mechanism, the most effective class. We found this interesting idea difficult to reconcile with various observations.
What Drives Built‐Up Area Expansion on Islands? Using Soil Sealing Indicators to Estimate Built‐Up Area Patterns on Aegean Islands, Greece
Authors: Kizos Thanasis , Tsilimigkas Georgios , Karampela Sofia
Published: February 2017

The dispersion of built‐up areas in peri‐urban zones is considered an important, almost irreversible environmental threat, especially in coastal zones and islands. In this paper, we use soil sealing datasets derived from the European Environment Agency in order to estimate the expansion of built‐up areas in the North and South Aegean islands in Greece. We examine these differences in relation to socio‐economic features of the islands, especially tourism development, second home development and size and geographical position of the islands. The findings show divergent levels of soil sealing and a variety of spatial configurations, such as scattered growth of built‐up land in coastal areas and peri‐urban growth in rural areas. Higher cover of the total area of islands by sealed soil is related to tourism, but it seems that second homes are also an important driver, especially for smaller islands located relatively close to Athens. From a planning and management perspective, these findings can assist local or regional administration to assess the effectiveness of land use management plans and manage flows and processes.
The effect of urea on refractometric total protein measurement in dogs and cats with azotemia
Authors: Legendre Kelsey P. , Leissinger Mary , Le Donne Viviana , Grasperge Britton J. , Gaunt Stephen D.
Published: February 2017

Background

While protein is the predominant solute measured in plasma or serum by a refractometer, nonprotein substances also contribute to the angle of refraction. There is debate in the current literature regarding which nonprotein substances cause factitiously high refractometric total protein measurements, as compared to the biuret assay.

Objectives

The purpose of the study was to determine if the blood of azotemic animals, specifically with increased blood urea concentration, will have significantly higher refractometric total protein concentrations compared to the total protein concentrations measured by biuret assay.

Methods

A prospective case series was conducted by collecting data from azotemic (n = 26) and nonazotemic (n = 34) dogs and cats. In addition, an in vitro study was performed where urea was added to an enhanced electrolyte solution at increasing concentrations, and total protein was assessed by both the refractometer and spectrophotometer. Statistical analysis was performed to determine the effect of urea.

Results

The refractometric total protein measurement showed a positive bias when compared to the biuret protein measurement in both groups, but the bias was higher in the azotemic group vs the nonazotemic group. The mean difference in total protein measurements of the nonazotemic group (0.59 g/dL) was significantly less (P < .01) than the mean difference of the azotemic group (0.95 g/dL). The in vitro experiment revealed a positive bias with a proportional error.

Conclusions

This study demonstrated that increasing concentrations of urea significantly increased the total protein concentration measured by the refractometer as compared to the biuret assay, both in vivo and in vitro.
Automation in blood processing
Authors: El Ekiaby Magdy
Published: February 2017

Background

Transfusion of blood components; namely packed red cells, platelet concentrates, fresh frozen plasma and sometimes cryoprecipitate has become an integral part in the management of many clinical situations. Processing of whole blood into its components can be achieved manually or by automation.

Automation in Blood Processing

In order to reduce the laborious steps and standardize the quality of blood components several technologies have been developed to automate blood component preparation. The advantages of these technologies include reduction of a number of equipment, such as plasma extractors, electric sealers. This leads to reduction of workspace and consequently may increase production efficiency. It also reduces the work load for the operators since these automates usually include several steps like breaking of clamps, extraction of the blood components as well as sealing of the pilot lines between the blood bags. More over the automation will reduce the operator inter variability leading to production of more standardized blood components. Automation can be for the steps of separation of the components after centrifugation or can be done by modern processors that include both centrifugation and separation steps.

Conclusion

Automation of blood component preparation from whole blood offers several advantages that include reduction of standard equipment, space, workload to lab staff as well as more standardized bloodcomponents.
A Web-based Blended Learning Environment for Programming Languages: Students’ Opinions
Authors: Yağci Mustafa
Published: February 2017

A learning environment which increases the desire and efforts of students to attain learning goals leads to greater motivation and success. This study examines the negative and positive opinions of students regarding the effectiveness of the learning process and students’ success in a computer programming course in which face-to-face and web-based e-learning methods were blended. The study, for which the case study method is used, was carried out over a 12 week period with the participation of 44 students. A data collection tool consisting of open-ended questions was applied to the participants at the end of the process. The replies given by the participants to the data collection tool were analyzed using qualitative analysis techniques. At the end of the research, the evaluation and satisfaction scores of the students regarding the web-based blended learning environment were found to be positive to a high degree. The positive opinions of the students were focused particularly around four themes, namely "facilitating learning through the learning environment"; "providing interaction opportunities"; "encouraging research", "video support for the course". Negative opinions were gathered around the themes of "lack of sufficient teaching time", "experiencing technical failures", "course badly scheduled" and "comprehensiveness of the course content".
MARÍA VICTORIA PORRAS EN CLAVE CONSTRUCTIVISTA
Authors: Camargo Flórez Martín Alonso
Published: February 2017

El presente artículo rastrea en diversas fuentes documentales la trayectoria de la artista santandereana, María Victoria Porras, desde 1966 hasta 1981. A partir de este material, se propone una interpretación constructivista de algunas de sus obras que entra en diálogo con el contexto económico, histórico, político y social de su ciudad natal, Barrancabermeja, ciudad marcada por el desarrollo urbano vinculado a la industria petrolera. Una lectura que permite entender el modo en que se han articulado en sus obras la ausencia de la figura humana y su restitución en el lenguaje, la reconciliación de la naturaleza y la cultura a través de la tecnología, y la crítica al optimismo desarrollista desde cierta forma de entender la utopía. 
Del relato testimonial al cuerpo de la memoria: investigación performativa sobre la escenificación de testimonios de niños chilenos en dictadura.
Authors: Contreras María José
Published: February 2017

En el presente artículo presento una exégesis de la investigación performativa; Teatro y memoria. Estrategias de (re)presentación y elaboración escénica de la memoria traumática infantil; cuyo objetivo general fue explorar estrategias de escenificación de testimonios de personas que fueron niños y niñas durante la dictadura en Chile. El proyecto se realizó en dos etapas: durante el 2008 se recolectaron los testimonios y se desarrolló un primer laboratorio teatral, en una segunda etapa, realizada entre los años 2011-2012, se creó la obra testimonial Pajarito Nuevo la Lleva que fue presentada en diversos espacios teatrales y de memoria en Santiago de Chile. En este artículo identifico las distintas estrategias de puesta en escena y puesta en cuerpo de los testimonios recolectados, dando cuenta de algunas posibilidades de re-elaboración escénica de memorias del postconflicto.
Impact of Wall Temperature on Heat Transfer Coefficient and Aerodynamics for Three-Dimensional Turbine Blade Passage
Authors: Maffulli Roberto , He Li
Published: February 2017

The present work is aimed to examine how the heat transfer coefficient (HTC) and main three-dimensional (3D) passage aerodynamic features may be affected by a nonadiabatic wall temperature condition. A systematic computational study has been first carried out for a 3D nozzle guide vane (NGV) passage. The impacts of wall temperature on the secondary flows, trailing edge shock waves, and the passage flow capacity are discussed, underlining the connection and interactions between the wall temperature and the external aerodynamics of the 3D passage. The local discrepancies in HTC in these 3D flow regions can be as high as 30–40% when comparing low and high temperature ratio cases. The effort is then directed to a new three-point nonlinear correction method. The benefit of the three-point method in reducing errors in HTC is clearly demonstrated. A further study illustrates that the new method also offers much enhanced robustness in the wall heat flux scaling, particularly relevant when the wall thermal condition is also shown to influence the laminar–turbulent transition exhibited by two well-established transition models adopted in the present work.
Soft Spherical Tensegrity Robot Design Using Rod-Centered Actuation and Control
Authors: Chen Lee-Huang , Kim Kyunam , Tang Ellande , Li Kevin , House Richard , Zhu Edward Liu , Fountain Kimberley , Agogino Alice M. , Agogino Adrian , Sunspiral Vytas , Jung Erik
Published: February 2017

This paper presents the design, analysis, and testing of a fully actuated modular spherical tensegrity robot for co-robotic and space exploration applications. Robots built from tensegrity structures (composed of pure tensile and compression elements) have many potential benefits including high robustness through redundancy, many degrees-of-freedom in movement and flexible design. However, to take full advantage of these properties, a significant fraction of the tensile elements should be active, leading to a potential increase in complexity, messy cable, and power routing systems and increased design difficulty. Here, we describe an elegant solution to a fully actuated tensegrity robot: The TT-3 (version 3) tensegrity robot, developed at UC Berkeley, in collaboration with NASA Ames, is a lightweight, low cost, modular, and rapidly prototyped spherical tensegrity robot. This robot is based on a ball-shaped six-bar tensegrity structure and features a unique modular rod-centered distributed actuation and control architecture. This paper presents the novel mechanism design, architecture, and simulations of TT-3, an untethered, fully actuated cable-driven six-bar spherical tensegrity robot. Furthermore, this paper discusses the controls and preliminary testing performed to observe the system's behavior and performance and is evaluated against previous models of tensegrity robots developed at UC Berkeley and elsewhere.
Design and Preliminary Testing of Novel Injection Port Contamination Barrier Devices
Authors: Wax David B. , Hill Bryan
Published: February 2017

Prior studies have linked microbial contamination of intravenous (IV) ports and stopcocks with postoperative infections. Existing technologies to address contamination are not consistently utilized because of the time and effort they require. Herein, novel barrier devices were created that form a protective shell to passively prevent contact between injection sites and practitioner hands or environmental surfaces while still allowing rapid connection of a syringe for injection of medications via an opening in the shell. Prototypes were tested using a grossly contaminated environment and adenosine triphosphate (ATP)-bioluminescence assay. For eight pairs of unshielded versus shielded IV ports/stopcocks, average contamination was 4102 versus 35 RLU (p < 0.02), respectively, indicating that the devices could significantly reduce IV port/stopcock contamination.
Approximate Consensus of Multiagent Systems With Inaccurate Sensor Measurements
Authors: Sadikhov Teymur , Haddad Wassim M. , Yucelen Tansel , Goebel Rafal
Published: February 2017

One of the main challenges in robotics applications is dealing with inaccurate sensor data. Specifically, for a group of mobile robots, the measurement of the exact location of the other robots relative to a particular robot is often inaccurate due to sensor measurement uncertainty or detrimental environmental conditions. In this paper, we address the consensus problem for a group of agent robots with a connected, undirected, and time-invariant communication graph topology in the face of uncertain interagent measurement data. Using agent location uncertainty characterized by norm bounds centered at the neighboring agent's exact locations, we show that the agents reach an approximate consensus state and converge to a set centered at the centroid of the agents' initial locations. The diameter of the set is shown to be dependent on the graph Laplacian and the magnitude of the uncertainty norm bound. Furthermore, we show that if the network is all-to-all connected and the measurement uncertainty is characterized by a ball of radius r, then the diameter of the set to which the agents converge is 2r. Finally, we also formulate our problem using set-valued analysis and develop a set-valued invariance principle to obtain set-valued consensus protocols. Two illustrative numerical examples are provided to demonstrate the efficacy of the proposed approximate consensus protocol framework.
Modeling Complex Nonminimum Phase Zeros in Flexure Mechanisms
Authors: Cui Leqing , Okwudire Chinedum , Awtar Shorya
Published: February 2017

This paper presents a model to explain complex nonminimum phase (CNMP) zeros seen in the noncollocated frequency response of a large-displacement XY flexure mechanism, which employs multiple double parallelogram flexure modules (DPFMs) as building-blocks. Geometric nonlinearities associated with large displacement along with the kinematic under-constraint in the DPFM lead to a coupling between the X and Y direction displacements. Via a lumped-parameter model that captures the most relevant geometric nonlinearity, it is shown that specific combinations of the operating point (i.e., flexure displacement) and mass asymmetry (due to manufacturing tolerances) give rise to CNMP zeros. This model demonstrates the merit of an intentionally asymmetric design over an intuitively symmetric design in avoiding CNMP zeros. Furthermore, a study of how the eigenvalues and eigenvectors of the flexure mechanism vary with the operating point and mass asymmetry indicates the presence of curve veering when the system transitions from minimum phase to CNMP. Based on this, the hypothesis of an inherent correlation between CNMP zeros and curve veering is proposed.
Experimental Investigation of Dynamic Adsorption–Desorption of New Nonionic Surfactant on Carbonate Rock: Application to Enhanced Oil Recovery
Authors: Barati-Harooni Ali , Najafi-Marghmaleki Adel , Hosseini Seyed Moein , Moradi Siyamak
Published: February 2017

Surfactants have the potential to reduce the interfacial tension between oil and water and mobilize the residual oil. An important process which makes the surfactant injection to be less effective is loss of surfactant to porous medium during surfactant flooding. This study highlights the results of a laboratory study on dynamic adsorption and desorption of Trigoonella foenum-graceum (TFG) as a new nonionic surfactant. The experiments were carried out at confining pressure of 3000 psi and temperature of 50 °C. Surfactant solutions were continuously injected into the core plug at an injection rate of 0.5 mL/min until the effluent concentration was the same as initial surfactant concentration. The surfactant injection was followed by distilled water injection until the effluent surfactant concentration was reduced to zero. The effluent concentrations of surfactant were measured by conductivity technique. Results showed that the adsorption of surfactant is characterized by a short period of rapid adsorption, followed by a long period of slower adsorption, and also, desorption process is characterized by a short, rapid desorption period followed by a longer, slow desorption period. The experimental adsorption and desorption data were modeled by four well-known models (pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models). The correlation coefficient of models revealed that the pseudo-second-order model predicted the experimental data with an acceptable accuracy.
Improvement of Aerodynamic Performance of Cambered Airfoils Using Leading-Edge Slots
Authors: Beyhaghi Saman , Amano Ryoichi S.
Published: February 2017

Feasibility of increasing lift and decreasing drag by drilling narrow span-wide channels near the leading edge of NACA 4412 airfoils is investigated. It is proposed to drill two-segment slots that allow some of the incoming air to flow through them and then exit from the bottom surface of the airfoil. Such slots can result in an increased local pressure and thereby higher lift. Length, width, inlet angle, and exit angle of slots are varied to determine optimum configurations. Aerodynamic performance at different angles of attack (AoAs) and the chord-based Reynolds number of 1.6 × 106 is investigated. It is concluded that longer and narrower slots with exit streams more aligned with the air flowing below the airfoil can result in a higher lift. Also, in order to keep the slotted airfoils beneficial for AoAs greater than zero, it is proposed to (a) slightly lower the slot position with respect to the original design and (b) tilt up the first-leg by a few degrees. For the best design case considered, an average improvement of 8% is observed for lift coefficient over the entire range of AoA (with the maximum increase of 15% for AoA = 0), without any significant drag penalty.
Comparison of transabdominal ultrasound and electromagnetic transponders for prostate localization
Authors: Foster Ryan D. , Solberg Timothy D. , Li Haisen S. , Kerkhoff Andrew , Enke Charles A. , Willoughby Twyla R. , Kupelian Patrick A.
Published: February 2017

The aim of this study is to compare two methodologies of prostate localization in a large cohort of patients. Daily prostate localization using B‐mode ultrasound has been performed at the Nebraska Medical Center since 2000. More recently, a technology using electromagnetic transponders implanted within the prostate was introduced into our clinic (Calypso). With each technology, patients were localized initially using skin marks. Localization error distributions were determined from offsets between the initial setup positions and those determined by ultrasound or Calypso. Ultrasound localization data was summarized from 16,619 imaging sessions spanning seven years. Calypso localization data consists of 1524 fractions in 41 prostate patients treated in the course of a clinical trial at five institutions and 640 localizations from the first 16 patients treated with our clinical system. Ultrasound and Calypso patients treated between March and September 2007 at the Nebraska Medical Center were analyzed and compared, allowing a single institutional comparison of the two technologies. In this group of patients, the isocenter determined by ultrasound‐based localization is on average 5.3 mm posterior to that determined by Calypso, while the systematic and random errors and PTV margins calculated from the ultrasound localizations were 3–4 times smaller than those calculated from the Calypso localizations.

Our study finds that there are systematic differences between Calypso and ultrasound for prostate localization.

PACS number: 87.63.dh
Dosimetric effects of air pocket sizes in MammoSite treatment as accelerated partial breast irradiation for early breast cancer
Authors: Huang Y. Jessica , Blough Melissa
Published: February 2017

MammoSite brachytherapy system has been used as one of the accelerated partial breast irradiation (APBI) techniques since 2002. The clinical results from several clinical institutions had shown comparable treatment efficacy, cosmesis, and toxicity to other APBI techniques. During MammoSite treatment, air cavities had been one of the primary issues causing treatment cancellation or delay. With the tolerance of the air volume less than 10% of the total Planning Target Volume (PTV) set, there is still no data available to show the actual dose delivered to the breast tissue with the existence of the air pocket. In this paper, Monte Carlo N‐Particle version 5 (MCNP5) was used to model a hypothesis MammoSite phantom with different sizes of air pockets, and compared to the calculation results from the treatment planning system (TPS) without heterogeneous corrections. It was found that without heterogeneous corrections, the difference between the TPS and MCNP5 calculations in the air cavity surface doses and PTV point doses can be up to 2.02% and 3.61%, respectively, using the balloon and air pocket size combinations calculated in this paper. Based on the distance from the point of interest to the balloon surface, an approximate dose can be calculated using the linear relationship found in this study. These equations provide a quick and simple way to predict the actual dose delivered to the breast soft tissue located within the PTV. With the equation applied to the dose from the TPS, the dose error caused by the air pocket during MammoSite treatment can be reduced to a minimum.

PACS number: 87.53.Jw
Investigation of a 3D system distortion correction method for MR images
Authors: Stanescu Teodor , Jans Hans‐Sonke , Wachowicz Keith , Fallone B. Gino
Published: February 2017

Interest has been growing in recent years in the development of radiation treatment planning (RTP) techniques based solely on magnetic resonance (MR) images. However, it is recognized that MR images suffer from scanner‐related and object‐induced distortions that may lead to an incorrect placement of anatomical structures. This subsequently may result in reduced accuracy in delivering treatment dose fractions in RTP. To accomplish the accurate representation of anatomical targets required by RTP, distortions must be mapped and the images rectified before being used in the clinical process. In this work, we investigate a novel, phantom‐based method that determines and corrects for 3D system‐related distortions. The algorithm consists of two key components: an adaptive control point identification and registration tool and an iterative method that finds the best estimate of 3D distortion. It was found that the 3D distortions were successfully mapped to within the voxel resolution of the raw data for a volume.

PACS numbers: 87.61.‐c, 87.53.Tf, 87.53.Xd, 87.56.‐v, 87.56.Fc, 87.62.+n
Development of a deformable lung phantom for the evaluation of deformable registration
Authors: Chang Jina , Suh Tae‐Suk , Lee Dong‐Soo
Published: February 2017

A deformable lung phantom was developed to simulate patient breathing motion and to evaluate a deformable image registration algorithm. The phantom consisted of an acryl cylinder filled with water and a latex balloon located in the inner space of the cylinder. A silicon membrane was attached to the inferior end of the phantom. The silicon membrane was designed to simulate a real lung diaphragm and to reduce motor workload. This specific design was able to reduce the use of metal, which may prevent infrared sensing of the real position management (RPM) gating system for four‐dimensional (4D) CT image acquisition. Verification of intensity based three‐dimensional (3D) demons deformable registration was based on the peak exhale and peak inhale breathing phases. The registration differences ranged from 0.60 mm to 1.11 mm and accuracy was determined according to inner target deformation. The phantom was able to simulate features and deformation of a real human lung and has the potential for wide application for 4D radiation treatment planning.

PACS number: 87.57.Gg
Absorbed dose and dose rate using the Varian OBI 1.3 and 1.4 CBCT system
Authors: Palm Åsa , Nilsson Elisabeth , Herrnsdorf Lars
Published: February 2017

According to published data, the absorbed dose used for a CBCT image acquisition with Varian OBI v1.3 can be as high as 100 mGy. In 2008 Varian released a new OBI version (v1.4), which promised to reduce the imaging dose. In this study, absorbed doses used for CBCT image acquisitions with the default irradiation techniques of Varian OBI v1.3 and v1.4 are measured.

TLDs are used to derive dose distributions at three planes inside an anthropomorphic phantom. In addition, point doses and dose profiles inside a ‘stack’ of three CTDI body phantoms are measured using a new solid state detector, the CT Dose Profiler. With the CT Dose Profiler, the individual pulses from the X‐ray tube are also studied. To verify the absorbed dose measured with the CT Dose Profiler, it is compared to TLD. The image quality is evaluated using a Catphan phantom.

For OBI v1.3, doses measured in transverse planes of the Alderson phantom range between 64 mGy and 144 mGy. The average dose is around 100 mGy. For OBI v1.4, doses measured in transverse planes of the Alderson phantom range between 1 mGy and 51 mGy. Mean doses range between 3‐35 mGy depending on CBCT mode. CT Dose Profiler data agree with TLD measurements in a CTDI phantom within the uncertainty of the TLD measurements (estimated SD ). Instantaneous dose rate at the periphery of the phantom can be higher than 20 mGy/s, which is 10 times the dose rate at the center. The spatial resolution in v1.4 is not as high as in v1.3.

In conclusion, measurements show that the imaging doses for default modes in Varian OBI v1.4 CBCT system are significantly lower than in v1.3. The CT Dose Profiler is proven fast and accurate for CBCT applications.

PACS number: 87.53.Bn
Validation of dosimetric field matching accuracy from proton therapy using a robotic patient positioning system
Authors: Farr Jonathan B. , O'Ryan‐Blair Avril , Jesseph Frederick , Hsi Wen‐Chien , Allgower Chris E. , Mascia Anthony E. , Thornton Allan F. , Schreuder Andreas N.
Published: February 2017

Large area, shallow fields are well suited to proton therapy. However, due to beam production limitations, such volumes typically require multiple matched fields. This is problematic due to the relatively narrow beam penumbra at shallow depths compared to electron and photon beams. Therefore, highly accurate dose planning and delivery is required. As the dose delivery includes shifting the patient for matched fields, accuracy at the 1–2 millimeter level in patient positioning is also required. This study investigates the dosimetric accuracy of such proton field matching by an innovative robotic patient positioner system (RPPS). The dosimetric comparisons were made between treatment planning system calculations, radiographic film and ionization chamber measurements. The results indicated good agreement amongst the methods and suggest that proton field matching by a RPPS is accurate and efficient.

PACS number: 87.55.km
Volume assessment accuracy in computed tomography: a phantom study
Authors: Prionas Nicolas D. , Ray Shonket , Boone John M.
Published: February 2017

There is a broad push in the cancer imaging community to eventually replace linear tumor measurements with three‐dimensional evaluation of tumor volume. To evaluate the potential accuracy of volume measurement in tumors by CT, a gelatin phantom consisting of 55 polymethylmethacrylate (PMMA) spheres spanning diameters from 1.6 mm to 25.4 mm was fabricated and scanned using thin slice (0.625 mm) CT (GE LightSpeed 16). Nine different reconstruction combinations of field of view dimension and CT kernel (standard, lung, bone) were analyzed. Contiguous thin‐slice images were averaged to produce CT images with greater thicknesses (1.25, 2.50, 5.0 mm). Simple grayscale thresholding techniques were used to segment the PMMA spheres from the gelatin background, where a total of 1800 spherical volumes were evaluated across the permutations studied. The geometric simplicity of the phantom established upper limits on measurement accuracy. In general, smaller slice thickness and larger sphere diameters produced more accurate volume assessment than larger slice thickness and smaller sphere diameter. The measured volumes were smaller than the actual volumes by a common factor depending on slice thickness; overall, 0.625 mm slices produced on average 18%, 1.25 mm slices produced 22%, 2.5 mm CT slices produced 29%, and 5.0 mm slices produced 39% underestimates of volume (mm3). Field of view did not have a significant effect on volume accuracy. Reconstruction algorithm significantly affected volume accuracy , with the lung kernel having the smallest error, followed by the bone and standard kernels. The results of this investigation provide guidance for CT protocol development and may guide the development of more advanced techniques to promote quantitatively accurate CT volumetric analysis of tumors.

PACS number: 87.57.Q‐
Study of a spherical phantom for Gamma knife dosimetry
Authors: Zhu Dengsong , Austerlitz Carlos , Benhabib Sidi , Mota Helvecio , Allison Ron R. , Campos Diana
Published: February 2017

Four 16 cm diameter spherical phantoms were modeled in this study: a homogenous water phantom, and three water phantoms with 1 cm thick shell each made of different materials (PMMA, Plastic Water™ and polystyrene). The PENELOPE Monte Carlo code was utilized to simulate photon beams from the Leksell Gamma Knife (LGK) unit and to determine absorbed dose to water from a single 18 mm beam delivered to each phantom. A score spherical volume of 0.007 cm3 was used to simulate the dimensions of the sensitive volume of the Exradin A‐16 ionization chamber, in the center of the phantom. In conclusion, the PMMA shell filled with water required a small correction for the determination of the absorbed dose, while remaining within the statistical uncertainty of the calculations . Plastic Water™ and polystyrene shells can be used without correction. There is a potential advantage to measuring the 4 mm helmet output using these spherical water phantoms.

PACS numbers: 87.10.Rt, 87.50.cm
Assessment and management of radiotherapy beam intersections with the treatment couch
Authors: van Prooijen Monique , Kanesalingam Thilakshan , Islam Mohammad K. , Heaton Robert K.
Published: February 2017

The impact of the treatment couch on a radiotherapy plan is rarely fully assessed during the treatment planning process. Incorporating a couch model into the treatment planning system (TPS) enables the planner to avoid or dosimetrically evaluate beam‐couch intersections. In this work, we demonstrate how existing TPS tools can be used to establish this capability and assess the accuracy and effectiveness of the system through dose measurements and planning studies. Such capabilities may be particularly relevant for the planning of arc therapies.

Treatment couch top models were introduced into a TPS by fusing their CT image sets with the patient CT dataset. Regions of interest characterizing couch elements were then imported and assigned appropriate densities in the TPS. Measurements in phantom agreed with TPS calculations to within 2% dose and 1° gantry rotation. To clinically validate the model, a retrospective study was performed on patient plans that posed difficulties in beam‐couch intersection during setup. Beam‐couch intersection caused up to a 3% reduction in PTV coverage, defined by the 95% of the prescribed dose, and up to a 1% reduction in mean CTV coverage. Dose compensation strategies for IMRT treatments with beams passing through couch elements were investigated using a four‐field IMRT plan with three beams passing through couch elements. In this study, ignoring couch effects resulted in point dose reductions of .

A methodology for incorporating detailed couch characteristics into a TPS has been established and explored. The method can be used to predict beam‐couch intersections during planning, potentially eliminating the need for pretreatment appointments. Alternatively, if a beam‐couch intersection problem arises, the impact of the couch can be assessed on a case‐by‐case basis and a clinical decision made based on full dosimetric information.

PACS numbers: 87.53.Bn;87.55.Gh;87.55.de;87.56.nk
Evaluation of a fast method of EPID‐based dosimetry for intensity‐modulated radiation therapy
Authors: Nelms Benjamin E. , Rasmussen Karl H. , Tomé Wolfgang A.
Published: February 2017

Electronic portal imaging devices (EPIDs) could potentially be useful for intensity‐modulated radiation therapy (IMRT) QA. The data density, high resolution, large active area, and efficiency of the MV EPID make it an attractive option. However, EPIDs were designed as imaging devices, not dosimeters, and as a result they do not inherently measure dose in tissue equivalent media. EPIDose (Sun Nuclear, Melbourne, FL) is a tool designed for the use of EPIDs in IMRT QA that uses raw MV EPID images (no additional build‐up and independent of gantry angle, but with dark and flood field corrections applied) to estimate absolute dose planes normal to the beam axis in a homogeneous media (i.e. similar to conventional IMRT QA methods). However, because of the inherent challenges of the EPID‐based dosimetry, validating and commissioning such a system must be done very carefully, by exploring the range of use cases and using well‐proven “standards” for comparison. In this work, a multi‐institutional study was performed to verify accurate EPID image to dose plane conversion over a variety of conditions. Converted EPID images were compared to 2D diode array absolute dose measurements for 188 fields from 28 clinical IMRT treatment plans. These plans were generated using a number of commercially available treatment planning systems (TPS) covering various treatment sites including prostate, head and neck, brain, and lung. The data included three beam energies (6, 10, and 15 MV) and both step‐and‐shoot and dynamic MLC fields. Out of 26,207 points of comparison over 188 fields analyzed, the average overall field pass rate was 99.7% when DTA criteria were used (range 94.0–100 per field). The pass rates for more stringent criteria were 97.8% for DTA (range 82.0–100 per field), and 84.6% for DTA (range 54.7–100 per field). Individual patient‐specific sites as well, as different beam energies, followed similar trends to the overall pass rates.

PACS number: 87.53.Dq; 87.66.Jj