bluuebunny/crossref_metadata_2025 huggingface dataset:
Small and Medium‐Sized Towns in Europe: Conceptual, Methodological and Policy Issues
Authors: Servillo Loris , Atkinson Rob , Hamdouch Abdelillah
Published: February 2017

Despite that small and medium‐sized towns (SMSTs) have been, and continue to be, a central part of the history of Europe, these places have largely been neglected by urban research. The ESPON TOWN project, on which this Special Issue builds, sought to redress this neglect performing a comparative analysis of their position and role across Europe. In this introductory paper we discuss some of the theoretical and methodological challenges when it came to identifying, studying and analysing SMSTs and the theoretical framework developed to inform our understanding of SMSTs. In particular, three themes are discussed. The first one is about the ontological problem of defining a town. Administrative, morphological and functional perspectives are considered. The second one reflects on a wide array of interpretative approaches about the relationship between towns and their regional context. The third one is about the thematic and multi‐scalar perspectives that can characterise the policy approach to towns.
The Socio‐Economic Profiles of Small and Medium‐Sized Towns: Insights from European Case Studies
Authors: Hamdouch Abdelillah , Demaziere Christophe , Banovac Ksenija
Published: February 2017

This paper is part of the research on functional roles of European towns conducted by a group of researchers gathered around the ESPON project ‘TOWN’. Building on the systematic analysis of the socio‐economic dynamics of 31 European small and medium‐sized towns (SMSTs), we identified three profiles of their local economies. The first profile is defined as a dominant ‘residential’ economy that mostly relies on local activities that satisfy the needs of people in an area (residents, commuters or tourists). The second profile corresponds to a dominant ‘productive’ economy based on the production of goods and services to be mainly exported and consumed out of its area. The third profile is the mixed type that is characterised by an important share of activities in productive and residential sector with a complementary ‘creative‐knowledge’ dimension, based on entrepreneurship, creativity and collaboration in innovation. Moreover, we analysed the economic performance and the shift in profiles in order to detect in which way towns make choices between residential economy, competitiveness and innovation for their local development.
Embodied Emotions in the Geographies of Sexualities
Authors: Gorman‐Murray Andrew
Published: February 2017

This commentary responds to the papers comprising the themed issue ‘Geographies of Sexualities: Bodies, Spatial Encounters and Emotions’. I position the themed issue at the intersection of geographies of sexualities, embodied geographies and emotional geographies, and suggest how the papers collectively contribute to geographies of sexualities and to human geography more broadly. The themed issue entwines the themes of ‘the body’ and ‘emotions’ to advance understandings of embodied emotions in geographies of sexualities and beyond. I identify three ways in which embodied emotions are taken forward in geographical thinking. First, the capacity for emotionally embodied fieldwork generates insights into collective embodiment and communities of practice, at the same time contesting masculinist objectivity and detachment in knowledge production. Second, new spaces of encounter – such as online forums and social media – are not distinct from everyday geographies, but instead are part of a virtual‐physical emotional landscape that extends embodiment across material and digital environments. Third, the innovative combination of different elements of feminist geographical thinking – such as intersectionality, the body and emotion and affect – generates new understandings of inequality across and between social identities.
Evaluación del uso de la realidad aumentada en la educación musical
Authors: Amaya Cote Liliana , Santoyo Diaz Julian
Published: February 2017

La presente investigación se centró en el desarrollo de una metodología para usar la técnica de realidad aumentada (RA) con el fin de crear material didáctico musical que permita la promoción de la autonomía en el aprendizaje del estudiante. Partiendo de esta idea, se analizó y determinó las herramientas tecnológicas con realidad aumentada que facilitaran la creación del material didáctico multimedia (audio, video, imágenes y modelos 3D) para el aprendizaje y montaje de repertorio musical. Seguidamente se creó material didáctico con realidad aumentada, aplicando este material a un grupo experimental con el fin de determinar si existe alguna diferencia entre la implementación de realidad aumentada en la clase de música y el uso del método de enseñanza tradicional. Finalmente se evaluó el impacto a partir de una rúbrica a los dos grupos: control y experimental además de un cuestionario de satisfacción para el grupo experimental, que llegó a determinar las contribuciones del material didáctico en realidad aumentada en el aprendizaje autónomo.
Effects of Servers' Rack Location and Power Loading Configurations on the Thermal Management of Data Center Racks' Array
Authors: Nada S. A. , Elfeky K. E.
Published: February 2017

Effects of server/rack locations and server loading configurations on the thermal performance of data center racks' array are experimentally investigated using a scaled physical model simulating real data. Front and rear rack temperatures profiles, server temperatures, and performance indices supply/return heat index (SHI/RHI) are used to evaluate the thermal management of the racks' array. The results showed that (i) servers located in high level rack cabinet have the worst thermal performance, (ii) middle racks of the rack row showed optimum thermal performance and energy efficiency, and (iii) locating the servers of high power densities in the middle of the racks row improves the thermal performance and energy efficiency of the racks array.
Unsteady Flow Field and Coarse Droplet Measurements in the Last Stage of a Low-Pressure Steam Turbine With Supersonic Airfoils Near the Blade Tip
Authors: Bosdas Ilias , Mansour Michel , Kalfas Anestis I. , Abhari Reza S. , Senoo Shigeki
Published: February 2017

The largest share of electricity production worldwide belongs to steam turbines. However, the increase of renewable energy production has led steam turbines to operate under part load conditions and increase in size. As a consequence, long rotor blades will generate a relative supersonic flow field at the inlet of the last rotor. This paper presents a unique experiment work that focuses at the top 30% of stator exit in the last stage of an low pressure (LP) steam turbine test facility with coarse droplets and high wetness mass fraction under different operating conditions. The measurements were performed with two novel fast response probes: a fast response probe for three-dimensional flow field wet steam measurements and an optical backscatter probe for coarse water droplet measurements ranging from 30 μm up to 110 μm in diameter. This study has shown that the attached bow shock at the rotor leading edge is the main source of interblade row interactions between the stator and rotor of the last stage. In addition, the measurements showed that coarse droplets are present in the entire stator pitch with larger droplets located at the vicinity of the stator's suction side. Unsteady droplet measurements showed that the coarse water droplets are modulated with the downstream rotor blade-passing period. This set of time-resolved data will be used for in-house computational fluid dynamics (CFD) code development and validation.
Nano-Phase Change Materials for Electronics Cooling Applications
Authors: Colla Laura , Ercole Davide , Fedele Laura , Mancin Simone , Manca Oronzio , Bobbo Sergio
Published: February 2017

The present work aims at investigating a new challenging use of aluminum oxide (Al2O3) nanoparticles to enhance the thermal properties (thermal conductivity, specific heat, and latent heat) of pure paraffin waxes to obtain a new class of phase change materials (PCMs), the so-called nano-PCMs. The nano-PCMs were obtained by seeding 0.5 and 1.0 wt  % of Al2O3 nanoparticles in two paraffin waxes having melting temperatures of 45 and 55 °C, respectively. The thermophysical properties such as specific heat, latent heat, and thermal conductivity were then measured to understand the effects of the nanoparticles on the thermal properties of both the solid and liquid PCMs. Furthermore, a numerical comparison between the use of the pure paraffin waxes and the nano-PCMs obtained in a typical electronics passive cooling device was developed and implemented. A numerical model is accomplished to simulate the heat transfer inside the cavity either with PCM or nano-PCM. Numerical simulations were carried out using the ansys-fluent 15.0 code. Results in terms of solid and liquid phase fractions and temperatures and melting time were reported and discussed. They showed that the nano-PCMs determine a delay in the melting process with respect to the pure PCMs.
Collagen Organization in Facet Capsular Ligaments Varies With Spinal Region and With Ligament Deformation
Authors: Ban Ehsan , Zhang Sijia , Zarei Vahhab , Barocas Victor H. , Winkelstein Beth A. , Picu Catalin R.
Published: February 2017

The spinal facet capsular ligament (FCL) is primarily comprised of heterogeneous arrangements of collagen fibers. This complex fibrous structure and its evolution under loading play a critical role in determining the mechanical behavior of the FCL. A lack of analytical tools to characterize the spatial anisotropy and heterogeneity of the FCL's microstructure has limited the current understanding of its structure–function relationships. Here, the collagen organization was characterized using spatial correlation analysis of the FCL's optically obtained fiber orientation field. FCLs from the cervical and lumbar spinal regions were characterized in terms of their structure, as was the reorganization of collagen in stretched cervical FCLs. Higher degrees of intra- and intersample heterogeneity were found in cervical FCLs than in lumbar specimens. In the cervical FCLs, heterogeneity was manifested in the form of curvy patterns formed by collections of collagen fibers or fiber bundles. Tensile stretch, a common injury mechanism for the cervical FCL, significantly increased the spatial correlation length in the stretch direction, indicating an elongation of the observed structural features. Finally, an affine estimation for the change of correlation length under loading was performed which gave predictions very similar to the actual values. These findings provide structural insights for multiscale mechanical analyses of the FCLs from various spinal regions and also suggest methods for quantitative characterization of complex tissue patterns.
Continuous, Real-Time, Noninvasive Hemodynamic Cardiac Doppler Monitoring With a Novel Hands-Free Device: A Feasibility Study Compared to Standard Echo
Authors: Lancaster Gilead I. , Hay Ilan , Eldar Michael
Published: February 2017

This study sought to determine the feasibility of using noninvasive cardiac hemodynamics (NICHE), a new noninvasive Doppler-based device, to monitor real-time, simultaneous tissue and blood-flow Doppler measurements in a clinical setting, and to obtain preliminary performance data compared to a commercially available system. Doppler-based measurements have been shown to correlate well with invasive hemodynamic data and diastolic function, but their use in clinical applications has been limited by various technical issues. The NICHE device was developed to obtain simultaneous tissue and blood-flow Doppler measurements automatically, in real-time and in a hands-free manner. Thirty participants (ten normal volunteers and 20 patients in a cardiac rehab program) underwent standard echocardiographic/Doppler studies followed immediately by NICHE monitoring. Early diastolic transmitral blood-flow velocity (E) and tissue Doppler myocardial wall velocity during early relaxation (E′) were acquired using a standard echo device; and E/E′ was derived post hoc. NICHE measurements included E, E′, and directly measured instantaneous E/E′. NICHE was successfully used in 28 participants. Measurements of ENICHE ranged from 40 cm/s to over 120 cm/s and correlated well with Eecho (R = 0.93). ENICHE′ ranged from 2 to 23 cm/s and correlated well with the averaged Eecho′ (R = 0.91). Directly measured E/ENICHE′ ratios ranged from 3 to 23 and correlated well with derived E/Eecho′ (R = 0.91). The NICHE device can monitor patients in a hands-free manner and can supply real-time Doppler derived measurements of hemodynamic parameters and diastolic function that correlate well with measurements from standard echo devices.
Group Regional Consensus of Networked Lagrangian Systems With Input Disturbances
Authors: Liu Jun , Miao Zhonghua , Ji Jinchen , Zhou Jin
Published: February 2017

Networked multirobot systems under the coordinated control can perform tasks more effectively than a group of individually operating robots. This paper studies the group regional consensus of networked multirobot systems (formulated by second-order Lagrangian dynamics) having input disturbances under directed acyclic topology. An adaptive control protocol is designed to achieve group regional consensus of the networked Lagrangian systems with parametric uncertainties for both leader and leaderless cases. Sufficient conditions are established to guarantee group regional consensus for any prior given desired consensus errors. Compared with the existing work, a distinctive feature of the proposed control algorithm is that the stability analysis indicates the global validity of the obtained consensus results. Numerical examples are provided to demonstrate the effectiveness of the proposed scheme.
Partial-State Stabilization and Optimal Feedback Control for Stochastic Dynamical Systems
Authors: Rajpurohit Tanmay , Haddad Wassim M.
Published: February 2017

In this paper, we develop a unified framework to address the problem of optimal nonlinear analysis and feedback control for partial stability and partial-state stabilization of stochastic dynamical systems. Partial asymptotic stability in probability of the closed-loop nonlinear system is guaranteed by means of a Lyapunov function that is positive definite and decrescent with respect to part of the system state which can clearly be seen to be the solution to the steady-state form of the stochastic Hamilton–Jacobi–Bellman equation, and hence, guaranteeing both partial stability in probability and optimality. The overall framework provides the foundation for extending optimal linear-quadratic stochastic controller synthesis to nonlinear-nonquadratic optimal partial-state stochastic stabilization. Connections to optimal linear and nonlinear regulation for linear and nonlinear time-varying stochastic systems with quadratic and nonlinear-nonquadratic cost functionals are also provided. Finally, we also develop optimal feedback controllers for affine stochastic nonlinear systems using an inverse optimality framework tailored to the partial-state stochastic stabilization problem and use this result to address polynomial and multilinear forms in the performance criterion.
Simulation Technology on SOFC Durability With an Emphasis on Conductivity Degradation of ZrO2-Base Electrolyte
Authors: Yokokawa Harumi , Kishimoto Haruo , Shimonosono Taro , Yamaji Katsuhiko , Muramatsu Mayu , Terada Kenjiro , Yashiro Keiji , Kawada Tatsuya
Published: February 2017

Attempts have been made to simulate numerically the conductivity degradation of solid oxide fuel cell (SOFC) YSZ electrolyte; physicochemical model has been constructed on the basis of experimental conductivities of Pt/1%NiO-doped YSZ/Pt cells under OCV condition. The temperature effect was extracted from the time constant for degradation caused by one thermal activation process (namely Y-diffusion), whereas the oxygen potential effect was determined by those Raman peak ratios between the tetragonal and the cubic phases which linearly change in relation to the conductivity. The electrical properties of the YSZ electrolyte before and after the transformation are taken into account. The time constant is directly correlated with Y-diffusion with proper critical diffusion length (∼10 nm), while the Y-diffusion can be enhanced on the reduction of NiO; this gives rise to the oxygen potential dependence. The most important objective of simulating the conductivity degradation is to reproduce the oxygen potential profile shift on transformation. Detailed comparison between experimental and simulation results reveal that the shift of oxygen potential profile, therefore, the conductivity profile change inside the YSZ electrolyte can well account for the Raman spectra profile. This also reveals that with decreasing temperature, there appear other kinetic factors of weakening or diminishing enhancing effects by NiO reduction. This may be important in interpreting the ohmic losses in real stacks, because there are differences in time constant or in magnitude of degradation between the pellets and those industrial stacks in which transformation was confirmed by Raman spectroscopy.
Analytical Study and Experimental Validation of Copper II Sulfate and Potassium Ferri/Ferrocyanide Thermocells Using Onsager Flux Equations
Authors: Bates Alex M. , Zickel Ben , Krebs Steffen , Mukherjee Santanu , Schuppert Nicholas D. , Choi Moon Jong , Park Sam D.
Published: February 2017

Thermocells convert heat energy directly into electrical energy through charge-transfer reactions at the electrode–electrolyte interface. To perform an analytical study on the behavior of thermocells, the Onsager flux relationship was applied to thermocells, which used aqueous copper II sulfate and aqueous potassium ferri/ferrocyanide as the electrolyte. The transport coefficient matrices were calculated for each electrolyte and applied to several simulations, which were subsequently validated through experimental testing and comparison to previous literature results. The simulation is shown to correctly predict the short circuit current, maximum power output, and power conversion efficiency. Validation demonstrates that the simulation model developed, using the Onsager flux equations, works for thermocells with different electrode materials (platinum, copper, charcoal, acetylene black, and carbon nanotube), electrode spacing, and temperature differentials. The power dependence of the thermocell on concentration and electrode spacing, with respect to the Seebeck coefficient, maximum power output, and relative efficiency, is also shown.
Experimental Study and Simulation of a Small-Scale Horizontal-Axis Wind Turbine
Authors: Jackson Randall S. , Amano Ryoichi
Published: February 2017

The advancement of wind energy as an alternative source to hydrocarbons depends heavily on research activities in turbulence modeling and experimentation. The velocity deficit behind wind turbines affects the power output and efficiency of a wind farm. Being able to simulate the wake dynamics of a wind turbine effectively can result in optimum spacing, longer wind turbine life, and shorter payback on the wind farm investment. Two-equation turbulence closure models, such as k–ε and k–ω, are used extensively to predict wind turbine performance and velocity deficit profiles. The application of the Reynolds stress model (RSM) turbulence closure method has been limited to few studies where the rotor is modeled as an actuator disk (AD). The computational cost associated with RSM has made it challenging for simulations where the rotor is discretized directly; however, with advances in computer speed and power coupled with parallel computing architecture, RSM may be a better turbulence closure option. In this research, wind tunnel experiments were conducted, using hot-wire anemometry, to measure the velocity deficit profiles at different wake locations behind a small-scale, three-bladed, horizontal-axis wind turbine (HAWT). Experiments were also performed with two and three HAWTs in series to evaluate the change in velocity deficit and turbulence intensity (TI). High-speed imaging with an oil-based mist captured the vortices produced at the blade tips and showed the vortices dissipated approximately three rotor diameters downstream. Computational fluid dynamics (CFD) simulations were performed to predict the velocity deficit at wake locations matching the experiments. The Reynolds stress model was applied to a fully discretized rotor with a tower and nacelle included in the simulation. A steady-state moving reference frame (MRF) model was created with the computational domain subdivided into rotating and stationary domains. The MRF results were used as an initial condition for time-accurate rigid body motion (RBM) simulations. The RBM CFD simulations showed excellent agreement with experimental measurements for velocity deficit after properly accounting for experimental boundary effects. Isosurfaces of the Q-criterion highlighted the vortices produced at the blade tips and were consistent with high-speed images.
Self-Healing of Wind Turbine Blades Using Microscale Vascular Vessels
Authors: Matt Arun Kumar Koralagundi , Beyhaghi Saman , Amano Ryoichi S. , Guo Jie
Published: February 2017

Development of high bending stresses due to a sudden gust of wind is a significant cause for the failure of wind turbine blades. Self-healing provides a fool proof safety measure against catastrophic failure by healing the damages autonomously, as they originate. In this study, biomimetic, vascular channel type of self-healing was implemented in glass fiber reinforced polymer matrix composite that is used in wind turbine blades. Microscale borosilicate tubes are used to supply the healing agent to the epoxy type of thermoset polymer matrix, and the healing was very effective. However, 25% decrease in tensile strength and 9% decrease in three-point bending flexural strength were imminent with the inclusion of a single layer of vascular vessels in the composite material. Three-point bending tests were performed before and after self-healing of flat specimens to find the extent of recovery of flexural strength on using vascular channel type of self-healing. An average recovery of flexural strength of 84.52% was obtained using a single layer of vascular vessels on the tensile stress side of three-point bending. Breakage and bleeding of the healing agent within the composite specimens during three-point bending tests were observed in real-time. Based on the encouraging findings, the above self-healing feature was successfully implemented in a prototype wind turbine.
The utility of non‐axial treatment beam orientations for lower lobe lung cancers
Authors: Quaranta Brian P. , Das Shiva K. , Shafman Timothy D. , Light Kim L. , Marks Lawrence B.
Published: February 2017

Traditional treatment beams for non‐small–cell lung cancer are limited to the axial plane. For many tumor geometries, non‐axial orientations appear to reduce the dose to normal tissues (e.g. heart, liver). We hypothesize that non‐axial beams provide a significant reduction in incidental irradiation of the heart and liver, while maintaining adequate target coverage. CT scans of twenty‐four patients with lower lobe lung cancers were studied. For each patient, an opposed oblique axial beam pair and a competing non‐axial opposed oblique pair were generated, both off‐cord. The competing plans delivered comparable doses/margins to the GTV. DVHs and integral doses were computed for all structures of interest for the two competing plans. The integral dose was compared for axial and non‐axial beams for each contoured organ using a paired t‐test. Dose to the heart was significantly lower for the non‐axial plans (). For 20/24 patients, the integral heart dose was reduced by using non‐axial beams. In those patients with tumors located in the inferior right lower lobe, a lower dose to the liver was achieved when non‐axial beams were used. There were no meaningful differences in dose to the GTV, lungs, or skin between axial and non‐axial beams. Non‐axial beams can reduce the dose to the heart and liver in patients with lower lobe lung cancers. Non‐axial beams may be clinically beneficial in these patients and should be considered as an option during planning.

PACS number: 87.55.de
A computational tool for the efficient analysis of dose‐volume histograms for radiation therapy treatment plans
Authors: Pyakuryal Anil , Myint W. Kenji , Gopalakrishnan Mahesh , Jang Sunyoung , Logemann Jerilyn A. , Mittal Bharat B.
Published: February 2017

A Histogram Analysis in Radiation Therapy (HART) program was primarily developed to increase the efficiency and accuracy of dose–volume histogram (DVH) analysis of large quantities of patient data in radiation therapy research. The program was written in MATLAB to analyze patient plans exported from the treatment planning system in the American Association of Physicists in Medicine/Radiation Therapy Oncology Group (AAPM/RTOG) format. HART‐computed DVH data was validated against manually extracted data from the planning system for five head and neck cancer patients treated with the intensity‐modulated radiation therapy (IMRT) technique. HART calculated over 4000 parameters from the differential DVH (dDVH) curves for each patient in approximately 10–15 minutes. Manual extraction of this amount of data required 5 to 6 hours. The normalized root mean square deviation (NRMSD) for the HART–extracted DVH outcomes was less than 1%, or within 0.5% distance‐to‐agreement (DTA). This tool is supported with various user‐friendly options and graphical displays. Additional features include optimal polynomial modeling of DVH curves for organs, treatment plan indices (TPI) evaluation, plan‐specific outcome analysis (POA), and spatial DVH (zDVH) and dose surface histogram (DSH) analyses, respectively. HART is freely available to the radiation oncology community.

PACS numbers: 87.53.‐j; 87.53.Tf; 87.53.Xd.
Evaluation of three APBI techniques under NSABP B‐39 guidelines
Authors: Scanderbeg Daniel , Yashar Catheryn , White Greg , Rice Roger , Pawlicki Todd
Published: February 2017

This work compares two accelerated partial breast irradiation modalities, MammoSite brachytherapy and three‐dimensional conformal radiotherapy (3D‐CRT), to a new method, strut‐adjusted volume implant (SAVI) brachytherapy, following NSABP B‐39 guidelines. A total of 21 patients treated at UC San Diego with the SAVI device were evaluated in this comparison. Nine of the 21 patients were eligible for all three modalities and were dosimetrically compared evaluating V90, V150, V200, total target volume, maximum skin, lung, and chestwall/rib dose. The target volumes (PTV_EVAL) differed with SAVI, having the least total volume at 59.9 cc vs. 71.5 cc and 351.6 cc for MammoSite and 3D‐CRT, respectively. The median V90, V150 and V200 for the three modalities were 97.7%, 25.0 cc, 10.4 cc (SAVI) vs. 97.6%, 23.9 cc, 5.0 cc (MammoSite) vs. 100% (V90 3D‐CRT). The maximum dose for SAVI, MammoSite, and 3D‐CRT, respectively, relative to the prescribed dose, for the lung: 80.0%, 150.0%, and 104.9%; for rib: 108.8%, 225.0%, and 114.7%; for skin: 75.0%, 135.0%, and 108.6%. Comparing modalities, PTV coverage varied between 97.6%–100.0% with more breast tissue covered by 3D‐CRT, as expected, given the differences between external beam and brachytherapy. The maximum lung, skin and rib doses were lowest for the SAVI, highlighting its ability to conform to exclude normal tissues. In offering partial breast radiation, the availability of a variety of techniques allows for maximal patient eligibility, and comparison of individual method pros and cons may guide the most appropriate choice for each patient.

PACS number: 87.53.Jw; 87.53.Kn; 87.55.D
Acrylonitrile Butadiene Styrene (ABS) plastic‐based low cost tissue equivalent phantom for verification dosimetry in IMRT
Authors: Kumar Rajesh , Sharma S.D. , Despande Sudesh , Ghadi Yogesh , Shaiju V.S. , Amols H.I. , Mayya Y. S.
Published: February 2017

A novel IMRT phantom was designed and fabricated using Acrylonitrile Butadiene Styrene (ABS) plastic. Physical properties of ABS plastic related to radiation interaction and dosimetry were compared with commonly available phantom materials for dose measurements in radiotherapy. The ABS IMRT phantom has provisions to hold various types of detectors such as ion chambers, radiographic/radiochromic films, TLDs, MOSFETs, and gel dosimeters. The measurements related to pretreatment dose verification in IMRT of carcinoma prostate were carried out using ABS and Scanditronix‐Wellhofer RW3 IMRT phantoms for five different cases. Point dose data were acquired using ionization chamber and TLD discs, while Gafchromic EBT and radiographic EDR2 films were used for generating 2D dose distributions. Treatment planning system (TPS) calculated and measured doses in ABS plastic and RW3 IMRT phantom were in agreement within . The dose values at a point in a given patient acquired using ABS and RW3 phantoms were found comparable within 1%. Fluence maps and dose distributions of these patients generated by TPS and measured in ABS IMRT phantom were also found comparable both numerically and spatially. This study indicates that ABS plastic IMRT phantom is a tissue‐equivalent phantom and, dosimetrically, it is similar to solid/plastic water IMRT phantoms. Although this material is demonstrated for IMRT dose verification, it can also be used as a tissue‐equivalent phantom material for other dosimetry purposes in radiotherapy.

PACS number: 87.53Kn, 87.55Qr, 87.53Bn and 87.55Km
Angular dose dependency of MatriXX TM and its calibration
Authors: Wolfsberger Luciant D. , Wagar Matthew , Nitsch Paige , Bhagwat Mandar S. , Zygmanski Piotr
Published: February 2017

One of the applications of MatriXX (IBA Dosimetry) is experimental verification of dose for IMRT, VMAT, and tomotherapy. For cumulative plan verification, dose is delivered for all the treatment gantry angles to a stationary detector. Experimental calibration of MatriXX detector recommended by the manufacturer involves only AP calibration fields and does not address angular dependency of MatriXX. Angular dependency may introduce dose bias in cumulative plan verification if not corrected. For this reason, we characterized angular dependency of MatriXX and developed a method for its calibration. We found relatively large discrepancies in responses to posterior vs. anterior fields for four MatriXX (Evolution series) detectors (up to 11%), and relatively large variability of responses as a function of gantry angle in the gantry angle ranges of 91°–110° and 269°–260°. With our calibration method, the bias due to angular dependency is effectively removed in experimental verification of IMRT and VMAT plans.

PACS number: 87.56Fc
Average CT in PET studies of colorectal cancer patients with metastasis in the liver and esophageal cancer patients
Authors: Tonkopi Elena , Chi Pai‐Chun Melinda , Mawlawi Osama , Riegel Adam C. , Rohren Eric M. , Macapinlac Homer A. , Pan Tinsu
Published: February 2017

Average CT (ACT) and PET have a similar temporal resolution and it has been shown to improve registration of the CT and PET data for PET/CT imaging of the thorax. The purpose of this study was to quantify the effect of ACT attenuation correction on PET for gross tumor volume (GTV) delineation with standardized uptake value (SUV) for liver and esophageal lesions. Our study included 48 colorectal cancer patients with metastasis in the liver and 52 esophageal cancer patients. These patients underwent a routine PET/CT scan followed by a cine CT scan of the thoracic region for ACT. Differences between the two PET data sets ( and ) corrected with the helical CT (HCT) and ACT were quantified by analyzing image alignment, maximum SUV , and GTV. The 67% of the colorectal and 73% of the esophageal studies demonstrated misregistration between the and HCT data. ACT was effective in removing misregistration artifacts in 65% of the misregisted colorectal and in 76% of the misregisted esophageal cancer patients. Misregistration between the CT and PET data affected GTVs due to the change in with ACT. A change of greater than 20% between and was found in 15% of the colorectal and 17% of the esophageal cases. Our results demonstrated a more pronounced effect of misregistration for the smaller lesions near the diaphragm . ACT was effective in improving registration between the CT and PET data in PET/CT for the colorectal and esophageal cancer patients.

PACS number: 87.58.Fg
A simple algorithm to assess patient suitability for Calypso‐seed implantation for four‐dimensional prostate localization
Authors: Kimple Randall J. , Wallen Eric M. , Pruthi Raj , Marks Lawrence B.
Published: February 2017

To retrospectively determine the proportion of prostate cancer patients who are appropriate candidates for prostate localization with Calypso (Calypso Medical, Seattle, WA); to assess the accuracy of surface anatomy in predicting prostate depth; and to describe a simple clinical algorithm predicting patient's appropriateness for Calypso localization. Medical records and archived CT scans of all patients treated for localized prostate cancer at our institution between 2006 and 2007 were reviewed. Association between the feasibility of Calypso use, the depth of the prostate from the anterior torso, and a variety of anatomic factors were assessed (ANOVA, linear regression, and ROC). Patients were appropriate for the Calypso system in 91% of cases (localize and track, 52%; localize only, 39%). Strong correlation between greater trochanter location and the posterior prostate was seen , mean difference 0.6 cm). The negative predictive value of the greater trochanter measurements was 31%. Thirty‐one out of forty‐five patients (69%) who were deemed inappropriate for Calypso based on greater trochanter to anterior torso measurements were eligible on the basis of CT‐based measurements of prostate depth. Weight, BMI, waist circumference, and hip circumference correlated with distance from the prostate to the anterior torso and were predictive of Calypso appropriateness. All patients with weight , or waist/hip circumference , were eligible for Calypso. Most prostate cancer patients are candidates for Calypso localization ± tracking. The greater trochanter to anterior torso distance underestimates the number of eligible patients. Weight, BMI and waist/hip circumference are good predictors for Calypso appropriateness.

PACS number: 87.63.‐d
Dosimetric characteristics of an electron multileaf collimator for modulated electron radiation therapy
Authors: Eldib Ahmed A. , ElGohary Mohamed I. , Fan Jiajin , Jin Lihui , Li Jinsheng , Ma C‐M Charlie , Elsherbini Nader A.
Published: February 2017

Modulated electron radiation therapy (MERT) has been proven as an effective way to deliver conformal dose distributions to shallow tumors while sparing distal critical structures and surrounding normal tissues. It had been shown that a dedicated electron multileaf collimator (eMLC) is necessary to reach the full potential of MERT. In this study, a manually‐driven eMLC for MERT was investigated. Percentage depth dose (PDD) curves and profiles at different depths in a water tank were measured using ionization chamber and were also simulated using the Monte Carlo method. Comparisons have been performed between PDD curves and profiles collimated using the eMLC and conventional electron applicators with similar size of opening. Monte Carlo simulations were performed for all electron energies available (6, 9, 12, 15, 18 and 20 MeV) on a Varian 21EX accelerator. Monte Carlo simulation results were compared with measurements which showed good agreement . The simulated dose distributions resulting from multiple static electron fields collimated by the eMLC agreed well with measurements. Further studies were carried out to investigate the properties of abutting electron beams using the eMLC, as it is an essential issue that needs to be addressed for optimizing the MERT outcome. A series of empirical formulas for abutting beams of different energies have been developed for obtaining the optimum gap sizes, which can highly improve the target dose uniformity.

PACS numbers: 87.53.Wz, 87.53.Hv
High‐precision GAFCHROMIC EBT film‐based absolute clinical dosimetry using a standard flatbed scanner without the use of a scanner non‐uniformity correction
Authors: Chung Heeteak , Lynch Bart , Samant Sanjiv
Published: February 2017

To report a study of the use of GAFCHROMIC EBT radiochromic film (RCF) digitized with a commercially available flatbed document scanner for accurate and reliable all‐purpose two‐dimensional (2D) absolute dosimetry within a clinical environment. We used a simplified methodology that yields high‐precision dosimetry measurements without significant postirradiation correction. The Epson Expression 1680 Professional scanner and the Epson Expression 10000XL scanner were used to digitize the films. Both scanners were retrofitted with light‐diffusing glass to minimize the effects of Newton rings. Known doses were delivered to calibration films. Flat and wedge fields were irradiated with variable depth of solid water and 5 cm back scatter solid water. No particular scanner nonuniformity effect corrections or significant post‐scan image processing were carried out. The profiles were compared with CC04 ionization chamber profiles. The depth dose distribution was measured at a source‐to‐surface distance (SSD) of 100 cm with a field size of . Additionally, 22 IMRT fields were measured and evaluated using gamma index analysis. The overall accuracy of RCF with respect to CC04 was found to be 2%–4%. The overall accuracy of RCF was determined using the absolute mean of difference for all flat and wedge field profiles. For clinical IMRT fields, both scanners showed an overall gamma index passing rate greater than 90%. This work demonstrated that EBT films, in conjunction with a commercially available flatbed scanner, can be used as an accurate and precise absolute dosimeter. Both scanners showed that no significant scanner nonuniformity correction is necessary for accurate absolute dosimetry using the EBT films for field sizes smaller than or equal to .

PACS number: 87.53.Bn
Evaluation of a commercial flatbed document scanner and radiographic film scanner for radiochromic EBT film dosimetry
Authors: Matney Jason E. , Parker Brent C. , Neck Daniel W. , Henkelmann Greg , Rosen Isaac I.
Published: February 2017

The purpose of this study was to quantify the performance and assess the utility of two different types of scanners for radiochromic EBT film dosimetry: a commercial flatbed document scanner and a widely used radiographic film scanner. We evaluated the Epson Perfection V700 Photo flatbed scanner and the Vidar VXR Dosimetry Pro Advantage scanner as measurement devices for radiochromic EBT film. Measurements were made of scan orientation effects, response uniformity, and scanner noise. Scanners were tested using films irradiated with eight separate fields to doses ranging from 0.115–5.119 Gy. ImageJ and RIT software was used for analyzing the Epson and Vidar scans, respectively. For repeated scans of a single film, the measurements in each dose region were reproducible to within standard deviation (SD) with both scanners. Film‐to‐film variations for corresponding doses were measured to be within SD for both Epson scanner and Vidar scanners. Overall, the Epson scanner showed a 10% smaller range of pixel value compared to the Vidar scanner. Scanner noise was small: SD for the Epson and for the Vidar. Overall measurement uniformity for blank film in both systems was better than , provided that the leading and trailing 2 cm film edges were neglected in the Vidar system. In this region artifacts are attributed to the film rollers. Neither system demonstrated a clear measurement advantage. The Epson scanner is a relatively inexpensive method for analyzing radiochromic film, but there is a lack of commercially available software. For a clinic already using a Vidar scanner, applying it to radiochromic film is attractive because commercial software is available. However, care must be taken to avoid using the leading and trailing film edges.

PACS number: 87.55.Qr
Management of an affiliated physics residency program using a commercial software tool
Authors: Zacarias Albert S. , Mills Michael D.
Published: February 2017

A review of commercially available allied health educational management software tools was performed to evaluate their capacity to manage program data associated with a CAMPEP‐accredited Therapy Physics Residency Program. Features of these software tools include: a) didactic course reporting and organization, b) competency reporting by topic, category and didactic course, c) student time management and accounting, and d) student patient case reporting by topic, category and course. The software package includes features for recording school administrative information; setting up lists of courses, faculty, clinical sites, categories, competencies, and time logs; and the inclusion of standardized external documents. There are provisions for developing evaluation and survey instruments. The mentors and program may be evaluated by residents, and residents may be evaluated by faculty members using this feature. Competency documentation includes the time spent on the problem or with the patient, time spent with the mentor, date of the competency, and approval by the mentor and program director. Course documentation includes course and lecture title, lecturer, topic information, date of lecture and approval by the Program Director. These software tools have the facility to include multiple clinical sites, with local subadministrators having the ability to approve competencies and attendance at clinical conferences. In total, these software tools have the capability of managing all components of a CAMPEP‐accredited residency program. The application database lends the software to the support of multiple affiliated clinical sites within a single residency program. Such tools are a critical and necessary component if the medical physics profession is to meet the projected needs for qualified medical physicists in future years.

PACS numbers: 87.90.+y, 87.53.‐j
Radiation skyshine from a 6 MeV medical accelerator
Authors: Gossman Michael S. , McGinley Patton H. , Rising Mary B. , Pahikkala A. Jussi
Published: February 2017

This study assesses the dose level from skyshine produced by a 6 MeV medical accelerator. The analysis of data collected on skyshine yields professional guidance for future investigators as they attempt to quantify and qualify radiation protection concerns in shielding therapy vaults. Survey measurements using various field sizes and at varying distances from a primary barrier have enabled us to identify unique skyshine behavior in comparison to other energies already seen in literature. In order to correctly quantify such measurements outside a shielded barrier, one must take into consideration the fact that a skyshine maximum may not be observed at the same distance for all field sizes. A physical attribute of the skyshine scatter component was shown to increase to a maximum value at 4.6 m from the barrier for the largest field size used. We recommend that the largest field sizes be used in the field for the determination of skyshine effect and that the peak value be further analyzed specifically when considering shielding designs.

PACS numbers: 87.52.‐g, 87.52.Df, 87.52.Tr, 87.53.‐j, 87.53.Bn, 87.53.Dq, 87.66.‐a, 89., 89.60.+x
Evaluation of the setup accuracy of a stereotactic radiotherapy head immobilization mask system using kV on‐board imaging
Authors: Ali Imad , Tubbs Jesse , Hibbitts Kerry , Algan Ozer , Thompson Spencer , Herman Terence , Ahmad Salahuddin
Published: February 2017

The purpose of this study was to evaluate setup accuracy and quantify random and systematic errors of the BrainLAB stereotactic immobilization mask and localization system using kV on‐board imaging. Nine patients were simulated and set up with the BrainLAB stereotactic head immobilization mask and localizer to be treated for brain lesions using single and hypofractions. Orthogonal pairs of projections were acquired using a kV on‐board imager mounted on a Varian Trilogy machine. The kV projections were then registered with digitally‐reconstructed radiographs (DRR) obtained from treatment planning. Shifts between the kV images and reference DRRs were calculated in the different directions: anterior‐posterior (A‐P), medial‐lateral (R‐L) and superior‐inferior (S‐I). If the shifts were larger than 2 mm in any direction, the patient was reset within the immobilization mask until satisfying setup accuracy based on image guidance has been achieved. Shifts as large as 4.5 mm, 5.0 mm, 8.0 mm in the A‐P, R‐L and S‐I directions, respectively, were measured from image registration of kV projections and DRRs. These shifts represent offsets between the treatment and simulation setup using immobilization mask. The mean offsets of 0.1 mm, 0.7 mm, and represent systematic errors of the BrainLAB localizer in the A‐P, R‐L and S‐I directions, respectively. The mean of the radial shifts is about 1.7 mm. The standard deviations of the shifts were 2.2 mm, 2.0 mm, and 2.6 mm in A‐P, R‐L and S‐I directions, respectively, which represent random patient setup errors with the BrainLAB mask. The BrainLAB mask provides a noninvasive, practical and flexible immobilization system that keeps the patients in place during treatment. Relying on this system for patient setup might be associated with significant setup errors. Image guidance with the kV on‐board imager provides an independent verification technique to ensure accuracy of patient setup. Since the patient may relax or move during treatment, uncontrolled and undetected setup errors may be produced with patients that are not well‐immobilized. Therefore, the combination of stereotactic immobilization and image guidance achieves more controlled and accurate patient setup within 2 mm in A‐P, R‐L and S‐I directions.

PACS numbers: 87.56.‐v, 87.56.Da
Evaluation of the interfractional biological effective dose (BED) variation in MammoSite high dose rate brachytherapy
Authors: Kim Yongbok , Werts E. Day , Trombetta Mark G. , Miften Moyed
Published: February 2017

The objective of this work is to evaluate the interfractional biological effective dose (BED) variation in MammoSite high dose rate (HDR) brachytherapy. Dose distributions of 19 patients who received 34 Gy in 10 fractions were evaluated. A method was employed to account for nonuniform dose distribution in the BED calculation. Furthermore, a range of α/β values was utilized for specific clinical end points: fibrosis, telangiectasia, erythema, desquamation and breast carcinoma. Two scenarios were simulated to calculate the BED value using: i) the same dose distribution of fraction 1 over fractions 2–10 (constant case, CC), and ii) the actual delivered dose distribution for each fraction 1–10 (interfraction dose variation case, IVC). Although the average BED difference (IVC – CC) was Gy for all clinical endpoints, the range of difference for fibrosis and telangiectasia reached to and to for one of the patients, respectively. By disregarding high inhomogeneity in HDR brachytherapy, the conventional BED calculation tends to overestimate the BED for fibrosis by 16% on average, while it underestimates the BED for erythema (7.6%) and desquamation (10.2%). In conclusion, the BED calculation accounting for the nonuniform dose distribution provides a more clinically relevant description of the clinical delivered dose. Though the average BED difference was clinically insignificant, the maximum difference of BED for late effects can differ by a single fractional dose (10%) for a specific patient due to the interfraction dose variation in MammoSite treatment.

PACS number: 87.53.Jw