bluuebunny/crossref_metadata_2025 huggingface dataset:
take up #9as a semantic isogloss on the Canada‐US border
Authors: DOLLINGER STEFAN
Published: July 2016

This paper explores semantic isoglosses of polysemous words, an understudied aspect of the Canada‐US border by drawing ontake up #9, an isogloss that appears to be spreading through the mainland Canadian population. The variable, which is approached from a philological‐lexicographic as well as a quantitative‐statistical perspective, is interpreted in the light of recent European cross‐borders studies. Analogues with the situations in Austrian German (Austria‐Germany) and British English (Scotland‐England) are drawn. Set in a pluricentric framework, this paper argues that the Canada‐US border remains a productive linguistic divide. Moreover, it is suggested that types of unexplored lexico‐semantic variables may be responsible for some identity work across this international border, one of only two contiguous borders among the Englishes of the Inner Circle.
Secondary hyperalgesia is mediated by heat‐insensitive A‐fibre nociceptors
Authors: van den Broeke Emanuel N. , Lenoir Cédric , Mouraux André
Published: July 2016

Key points

It is believed that secondary hyperalgesia (the increased sensitivity to mechanical nociceptive stimuli that develops after cutaneous tissue injury in the surrounding uninjured skin) is mediated by a subclass of nociceptors: the slowly adapting A‐fibre mechano‐heat nociceptors (AMH‐type I). Here we tested this hypothesis.

By using intense long‐lasting heat stimuli, which are known to activate these slowly adapting AMH‐type I nociceptors, we show that the perceived intensity elicited by these stimuli is not increased in the area of secondary hyperalgesia.

Moreover, we show that during an A‐fibre nerve conduction block the perception elicited by the long‐lasting heat stimuli is significantly reduced in a time window that matches the response profile of the AMH‐type I nociceptors.

AMH‐type I nociceptors contribute to the perception of sustained heat, but they do not mediate secondary hyperalgesia. Therefore, we propose that secondary hyperalgesia is mediated by high threshold mechanoreceptors.

Secondary hyperalgesia refers to the increase in sensitivity to mechanical nociceptive stimuli delivered outside the area of tissue injury. Previous studies have suggested that secondary hyperalgesia is mediated by a specific class of myelinated nociceptors: slowly adapting A‐fibre mechano‐ and heat‐sensitive (AMH) type I nociceptors. Here, we tested this hypothesis by examining whether long‐lasting heat stimuli, which are known to activate AMH‐type I nociceptors, elicit enhanced responses when delivered to the area of secondary hyperalgesia induced by high frequency electrical stimulation of the skin (HFS). Before and 20 min after HFS, sustained 30 s radiant heat stimuli were delivered to the area of increased mechanical pinprick sensitivity while participants continuously rated intensity of perception using an online visual analog scale (0–100 mm). After HFS, no significant enhancement of heat perception was observed in the area of increased pinprick sensitivity. To establish that myelinated nociceptors actually contribute to the perception of sustained heat, we conducted a second experiment in which sustained heat stimuli were presented before and during an A‐fibre nerve conduction block, achieved by applying a rubber band with weights which compresses the superficial radial nerve against the radius. During the block, heat perception was significantly reduced 17–33 s after the onset of the heat stimulus (before: mean = 53 mm, during: mean = 31 mm; P = 0.03), matching the response profile of AMH‐type I nociceptors. These results support the notion that AMH‐type I nociceptors contribute to the perception of sustained heat, but also show that these afferents do not mediate secondary hyperalgesia.
COBRA-TF Simulation of DNB Response During Reactivity-Initiated Accidents Using the NSRR Pulse Irradiation Experiments
Authors: Kucukboyaci Vefa N. , Cao Liping , Sung Yixing
Published: July 2016

COBRA-TF (Coolant Boiling in Rod Arrays–Two Fluid), or CTF, is a transient subchannel code selected to be the reactor core thermal-hydraulic simulation tool in the multiphysics code-development project of the Consortium for Advanced Simulation of Light Water Reactor (CASL) sponsored by the US Department of Energy (DOE). In this paper, CTF’s capability for departure from nucleate boiling (DNB) prediction is evaluated by modeling and simulating power-burst experiments with high-burnup pressurized water reactor (PWR) fuel rods, conducted at the Nuclear Safety Research Reactor (NSRR) in Japan. Experiments using reactor fuel segments have been modeled and simulated to evaluate CTF’s prediction capability for onset of DNB and heat transfer from single-phase to post-critical heat flux (CHF) during fast reactivity-initiated accident (RIA) transients. The calculations demonstrated that CTF is able to simulate a fast transient with a large power pulse. CTF predicted DNB occurrence in all of the cases, after the power pulse, consistent with experimental observations. In the experiments, all cases experienced DNB, as predicted by the correlations in CTF; however, fuel failure occurred in only two of the cases: one at the peak power and the other after the peak power. The remaining cases survived with enthalpies significantly higher than those that failed while experiencing DNB occurrences.
A New Approach to Thermal Analysis of a Multilayered Cylindrical Structure With Imperfect Bonds and Internal Heat Source
Authors: Bakhtiari M. , Daneshjou K. , Alibakhshi R.
Published: July 2016

In the present research, a new and straightforward mathematical model, named augmented state-space method, is introduced to solve the heat conduction equation for a multilayered orthotropic hollow cylinder with bonding imperfection in the presence of heat source. Since such problems including heat source are inherently inhomogeneous and complex, augmented state-space method converts these inhomogeneous equations into homogeneous ones. The transient solution will be achieved by present method based on laminate approximation theory in the Laplace domain, and then the solutions obtained are retrieved into the time domain by applying the numerical Laplace transform inversion. All material properties can be considered to vary continuously within the cylinder along the radial direction with arbitrary grading pattern. Based on the proposed method, the solution of heat conduction problem can be also obtained for general boundary conditions which may be included various combinations of arbitrary temperature, flux, or convection. Due to lack of any data on the transient thermal analysis corresponding to problems with imperfect bonds in the cylindrical coordinate system (r,θ), comparison is carried out with the available results for the three-layer semi-circular annular region with perfect bonds in the literature. Finally, the influence of orthotropy and interface imperfection on the distribution of the temperature field for three-layer hollow cylinder, in which the second layer is made of orthotropic functionally graded material (FGM), will be visualized.
Investigation of Single-Jet Combustor Near Lean Blowout Conditions Using Flamelet-Generated Manifold Combustion Model and Detailed Chemistry
Authors: Patil Sunil , Cooper Judy , Orsino Stefano , Meadows Joseph , Valdes Richard , Laster Walter R.
Published: July 2016

Numerical simulation results of a single-jet premixed combustion system at atmospheric pressure are compared against comprehensive particle image velocimetry (PIV) flow measurements and Raman scattering temperature measurements for natural gas and hydrogen fuels. The simulations were performed on hexahedral meshes with 1–5 × 106 elements. Reynolds-averaged Navier–Stokes (RANS) calculations were carried out with the k–ε realizable turbulence model. Combustion was modeled using the flamelet-generated manifold model (FGM) and detailed chemistry. Both the flame position and flame liftoff predicted by the FGM were in reasonable agreement with experiments for both fuels and showed little sensitivity to heat transfer or radiation modeling. The detailed chemistry calculation predicts the temperature gradients along the jet centerline accurately and compares very closely with the Raman scattering measurements. The much closer agreement of the jet axial velocity and temperature profiles with experimental values, coupled with the significantly protracted presence of intermediates in the detailed chemistry predictions, indicates that the impact of nonequilibrium intermediates on very lean natural gas flames is significant.
Improving Performance of a Switched Inertance Buck Converter Via Positioning of Reservoir Flow Valve
Authors: Wiens Travis
Published: July 2016

A typical switched inertance buck converter includes digital valves controlling the flow of fluid to the load from the pressure supply and also from the reservoir. These valves are typically located at the same position, often packaged in the form of a single three-way valve, but also sometimes in the form of a two-way high-pressure supply valve and check valve from tank. This results in the situation where attempts to increase flow boosting performance by exploiting reflected pressure waves to draw additional fluid from tank will also tend to draw additional fluid through the valve from the high-pressure supply, causing increased energy loss at the valve. This paper presents a strategy that avoids this tradeoff by locating the tank flow valve along the length of the inertance tube such that the timing of pressure waves arriving at the tank valve can be optimized separately from those arriving at the high-pressure supply valve. A simulation study is presented, in which valve placement and inertance tube resonance are optimized for flow gain or energy efficiency, with results in both cases better than a conventional system with colocated valves. Two strategies for avoiding cavitation are also presented.
A Loading Correction Scheme for a Structure-Dependent Integration Method
Authors: Chang Shuenn-Yih
Published: July 2016

A structure-dependent integration method may experience an unusual overshooting behavior in the steady-state response of a high frequency mode. In order to explore this unusual overshooting behavior, a local truncation error is established from a forced vibration response rather than a free vibration response. As a result, this local truncation error can reveal the root cause of the inaccurate integration of the steady-state response of a high frequency mode. In addition, it generates a loading correction scheme to overcome this unusual overshooting behavior by means of the adjustment the difference equation for displacement. Apparently, these analytical results are applicable to a general structure-dependent integration method.
Chaotic Behavior and Its Control in a Fractional-Order Energy Demand–Supply System
Authors: Chen Dongqin , Liu Wenjun
Published: July 2016

In this paper, we first propose a fractional-order energy demand–supply system, with the background of the energy resources demand in the eastern regions of China and the energy resources supply in the western regions of China. Then, we confirm the energy resource attractor with a necessary condition about the existence of chaotic behaviors. By employing an improved version of Adams Bashforth Moulton algorithm, we use three cases with different fractional values to verify the necessary condition. Finally, chaos control of fractional-order energy demand–supply system is investigated by two different control strategies: a linear feedback control and an adaptive switching control strategy via a single control input. Numerical simulations show that the energy demand and import in Eastern China and energy supply in Western China are self-feedback controlled around the system’s equilibrium point.
Maximum Heat Transfer and Operating Temperature of Oscillating Heat Pipe
Authors: Iwata Naoko , Ogawa Hiroyuki , Miyazaki Yoshiro
Published: July 2016

It is reported that the operating temperature of an oscillating heat pipe (OHP) at an operating limit is not dependent on the ambient temperature but that the maximum heat transfer is dependent on this. In this study, using different ambient temperature conditions, a 15-turn OHP filled with HFC-134a as a working fluid was operated until it dries out. The maximum heat transfer was found to vary with changes in the ambient temperature, but the operating temperature at an operating limit, which depends on the filling ratio (FR) of the working fluid, was found to be constant. At the operating limit, the operating temperature decreased with an increase in the FR when the ratio was greater than 50 wt.%. Visualization experiments and calculations were used to confirm that there is an increase in the liquid volume in the OHP in accordance with an increase in the heat input and that ultimately the OHP fills with the liquid, resulting in the failure of OHP operation. In contrast, at the operating limit, when the FR was less than 50%, the operating temperature increased in line with an increase in the FR. In this case, it is assumed that the volume of liquid slugs decreases as the heat input increases, thus causing the OHP to dry out. This theory is explained using a P–V diagram of the working fluid in the OHP. The OHP thermodynamic cycle reaches a saturated liquid or vapor line before it reaches a critical point if a specified volume is shifted from the specified volume at the critical point. The optimum FR for maximum heat transfer is therefore decided by the void ratio at the critical point of the working fluid.
Numerical Study of Natural Convection in a Ferrofluid-Filled Corrugated Cavity With Internal Heat Generation
Authors: Selimefendigil Fatih , Öztop Hakan F.
Published: July 2016

In this paper, numerical simulations for the natural convection in a ferrofluid-filled corrugated cavity with internal heat generation under the influence of a magnetic dipole source were performed. The cavity is heated from below and cooled from above while vertical side walls are assumed to be adiabatic. A magnetic dipole source was located under the bottom heated wall. The governing equations were solved by Galerkin weighted residual finite-element formulation. The influence of external Rayleigh number (between 104 and 5 × 105), internal Rayleigh number (between 104 and 5 × 106), magnetic dipole strength (between 0 and 4), horizontal (between 0.2 and 0.8) and vertical (between −5 and −2) locations of the magnetic dipole source on fluid flow, and heat transfer are numerically investigated. It was observed that depending on heating mechanism (the external or internal heating), the presence of corrugation of the bottom wall either enhances or deteriorates the absolute value of the averaged heat transfer. The strength and locations of the magnetic dipole source affect the distribution of the flow and thermal patterns within the cavity for both flat and corrugated wall cavity. The net effect of the complicated interaction of the internal heating, external heating, and ferroconvection of magnetic source results in heat transfer enhancement with increasing values of magnetic dipole strength. Wall corrugation causes more enhancement of averaged heat transfer and this is more pronounced for low values of vertical location of magnetic source.
Particle Filter and Approximation Error Model for State Estimation in Hyperthermia
Authors: Lamien Bernard , Barreto Orlande Helcio Rangel , Enrique Eliçabe Guillermo
Published: July 2016

This work deals with numerical simulation of a hyperthermia treatment of skin cancer as a state estimation problem, where uncertainties in the evolution and measurement models, as well as in the measured data, are accounted for. A reduced model is adopted, based on a coarse mesh for the solution of the partial differential equations that describe the physical problem, in order to expedite the solution of the state estimation problem with a particle filter algorithm within the Bayesian framework of statistics. The so-called approximation error model (AEM) is used in order to statistically compensate for model reduction effects. The Liu and West algorithm of the particle filter, together with the AEM, is shown to provide accurate estimates for the temperature and model parameters in a multilayered region containing a tumor loaded with nanoparticles. Simulated transient temperature measurements from one sensor are used in the analysis.
Thermodynamic Analysis of Simultaneous Heat and Mass Transfer Systems
Authors: Martinez-Patiño Jesus , Serra Luis , Verda Vittorio , Picón-Núñez Martin , Rubio-Maya Carlos
Published: July 2016

The direct heat exchange network (direct flow mixing network) and the indirect heat exchange network (exchanger network) are two of the elements that constitute a water network where heat and mass are transferred. When designing these systems, it is important to consider different aspects such as thermodynamics and equipment costs. This paper analyzes different design options within the framework of heuristic methodologies on a case study taken from the open literature. Two design methodologies are compared on the basis of exergy losses. It also enunciates a series of considerations in heuristic design for the heat and mass exchange networks. A very helpful tool in relation with the considerations set out herein is the composite curve; special focus will be given during its construction. This paper shows how to incorporate the exergy component in design seeking to minimize the thermal irreversibility.
Validation of Direct Beam Irradiance Measurements From Rotating Shadowband Irradiometers in a Region With Different Atmospheric Conditions
Authors: Geuder Norbert , Affolter Roman , Goebel Olaf , Dahleh Basel , Al Khawaja Mohamed , Wilbert Stefan , Pape Benedikt , Pulvermueller Benedikt
Published: July 2016

Rotating shadowband irradiometers (RSIs) are a common type of radiation sensors for measurement of direct normal irradiance (DNI) at remote sites where daily maintenance of the instruments is not feasible or practicable. Their primordial lower accuracy due to systematic deviations of the photodiode response can be improved significantly with a thorough calibration of each RSI against high precision sensors and application of suitable corrections on the raw data. With different available correction functions for the systematic errors, RSI data coincide with first class reference sensors within 2–3% root mean square deviation (RMSD) for 10 min averages of DNI and meet the annual irradiation sum within 1.5%. Such comparisons of RSI data to reference irradiances have only been published for a small number of sites. To endorse the credibility of RSI measurements, it has to be shown that these accuracies derived for certain locations are also valid at other sites with differing atmospheric conditions. Therefore, a parallel measurement campaign with six RSIs and a reference station with first class and secondary standard instrumentation has been performed in the in the extreme climate of the United Arab Emirates (UAE). The results of this comparison are presented in this paper. The stated empiric accuracy could be validated and confirmed for the UAE.
Effects of Partition on Thermal Comfort, Indoor Air Quality, Energy Consumption, and Perception in Air-Conditioned Buildings
Authors: Aryal Pradip , Leephakpreeda Thananchai
Published: July 2016

This research is to assess effects of a partition on thermal comfort, indoor air quality (IAQ), energy consumption, and perception in an air-conditioned space via computational fluid dynamics (CFD) analysis. The variables of indoor air are numerically determined before/after installation/removal of a partition. Accordingly, predicted mean vote (PMV) of thermal comfort, carbon dioxide concentration, rate of energy consumption in making up air, and an overall perception index are proposed to quantify effects in a partitioned space. For a case study, a partition is used to tightly separate a study area from a rest area in a library during peak time. The CFD analysis is performed so that the mean differences between the measured and simulated variables at 14 locations are less than 5%. After partitioning in the CFD analysis, it is found that the average PMV value decreases to −1.4 in the rest area, and it remains at −0.7 in the study area where occupants perceive a slightly cool sensation. In the study area, the carbon dioxide concentration increases to 450–500 ppm, while the rate of energy consumption increases by 8.3%. From the overall perception index of 0.9, the occupants feel spacious in the partitioned areas. Therefore, installing the partition is encouraged with the recommendation that cooling supply can be reduced for energy savings. It is apparent that the proposed methodology yields quantitative indicators for decision making of installation/removal of partitions. The interior investigation of partitions in buildings can be performed before making real physical changes.
SU‐A‐BRC‐03: The Path of a Small Business Owner
Authors: Childress N.
Published: July 2016

This year's Annual Student Meeting consists of a panel of professionals who have pursued a traditional education in medical physics and have since pursued a variety of careers. These range from chief medical physicist, small business founder, FDA scientist, industry R&D scientist, and academic researcher. Each panelist will discuss their education, positions that they have held leading to their current one, and factors that influenced them to pursue their careers. Time will be left at the end of the talk to open the floor for questions from students and trainees. Discussion between the presenters and participants is encouraged.

Learning Objectives:

The audience will learn about how to prepare for a career in medical physics.

The audience will be able to consider some of the widely different job opportunities open to medical physicists.

The audience will gain a better understanding of some future challenges facing medical physics graduates.

N. Childress, I am the owner of Mobius Medical Systems, LP.
SU‐B‐BRA‐01: Introduction
Authors: Sherouse G.
Published: July 2016

In the current rapidly changing Healthcare environment, many groups are competing for limited resources. How can medical physicists position themselves to be a relevant stakeholder in the discussion of how those resources are allocated Our value goes beyond what can be shown in a business plan and is heavily involved with safety and quality.

Three areas will be explored:

What is our value?

Who needs to receive that message?

How do we communicate that message?

To help frame the discussion in terms of how other stakeholders may view the value of medical physicists, a physician and an administrator will present their perspective.

Lastly, a multidisciplinary panel will present real life examples of strategies that can be utilized today to establish the value of medical physicists. The presentation of these examples will lead into an interactive question and answer time.

V. Willcut, I work for Elekta. There was no research associated with this talk.
SU‐C‐201‐04: Noise and Temporal Resolution in a Near Real‐Time 3D Dosimeter
Authors: Rilling M , Goulet M , Beaulieu L , Thibault S , Archambault L
Published: July 2016

Purpose:

To characterize the performance of a real‐time three‐dimensional scintillation dosimeter in terms of signal‐to‐noise ratio (SNR) and temporal resolution of 3D dose measurements. This study quantifies its efficiency in measuring low dose levels characteristic of EBRT dynamic treatments, and in reproducing field profiles for varying multileaf collimator (MLC) speeds.

Methods:

The dosimeter prototype uses a plenoptic camera to acquire continuous images of the light field emitted by a 10×10×10 cm3 plastic scintillator. Using EPID acquisitions, ray tracing‐based iterative tomographic algorithms allow millimeter‐sized reconstruction of relative 3D dose distributions. Measurements were taken at 6MV, 400 MU/min with the scintillator centered at the isocenter, first receiving doses from 1.4 to 30.6 cGy. Dynamic measurements were then performed by closing half of the MLCs at speeds of 0.67 to 2.5 cm/s, at 0° and 90° collimator angles. A reference static half‐field was obtained for measured profile comparison.

Results:

The SNR steadily increases as a function of dose and reaches a clinically adequate plateau of 80 at 10 cGy. Below this, the decrease in light collected and increase in pixel noise diminishes the SNR; nonetheless, the EPID acquisitions and the voxel correlation employed in the reconstruction algorithms result in suitable SNR values (>75) even at low doses. For dynamic measurements at varying MLC speeds, central relative dose profiles are characterized by gradients at %D50 of 8.48 to 22.7 %/mm. These values converge towards the 32.8 %/mm‐gradient measured for the static reference field profile, but are limited by the dosimeter's current acquisition rate of 1Hz.

Conclusion:

This study emphasizes the efficiency of the 3D dose distribution reconstructions, while identifying limits of the current prototype's temporal resolution in terms of dynamic EBRT parameters. This work paves the way for providing an optimized, second‐generational real‐time 3D scintillation dosimeter capable of highly efficient and precise dose measurements.

The presenting author is financially supported by an Alexander‐Graham Bell doctoral scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC).
SU‐C‐BRA‐07: Variability of Patient‐Specific Motion Models Derived Using Different Deformable Image Registration Algorithms for Lung Cancer Stereotactic Body Radiotherapy (SBRT) Patients
Authors: Dhou S , Ionascu D , Lewis J , Williams C
Published: July 2016

Purpose:

To study the variability of patient‐specific motion models derived from 4‐dimensional CT (4DCT) images using different deformable image registration (DIR) algorithms for lung cancer stereotactic body radiotherapy (SBRT) patients.

Methods:

Motion models are derived by 1) applying DIR between each 4DCT image and a reference image, resulting in a set of displacement vector fields (DVFs), and 2) performing principal component analysis (PCA) on the DVFs, resulting in a motion model (a set of eigenvectors capturing the variations in the DVFs). Three DIR algorithms were used: 1) Demons, 2) Horn‐Schunck, and 3) iterative optical flow. The motion models derived were compared using patient 4DCT scans.

Results:

Motion models were derived and the variations were evaluated according to three criteria: 1) the average root mean square (RMS) difference which measures the absolute difference between the components of the eigenvectors, 2) the dot product between the eigenvectors which measures the angular difference between the eigenvectors in space, and 3) the Euclidean Model Norm (EMN), which is calculated by summing the dot products of an eigenvector with the first three eigenvectors from the reference motion model in quadrature. EMN measures how well an eigenvector can be reconstructed using another motion model derived using a different DIR algorithm. Results showed that comparing to a reference motion model (derived using the Demons algorithm), the eigenvectors of the motion model derived using the iterative optical flow algorithm has smaller RMS, larger dot product, and larger EMN values than those of the motion model derived using Horn‐Schunck algorithm.

Conclusion:

The study showed that motion models vary depending on which DIR algorithms were used to derive them. The choice of a DIR algorithm may affect the accuracy of the resulting model, and it is important to assess the suitability of the algorithm chosen for a particular application.

This project was supported, in part, through a Master Research Agreement with Varian Medical Systems, Inc, Palo Alto, CA.
SU‐C‐209‐05: Monte Carlo Model of a Prototype Backscatter X‐Ray (BSX) Imager for Projective and Selective Object‐Plane Imaging
Authors: Rolison L , Samant S , Baciak J , Jordan K
Published: July 2016

Purpose:

To develop a Monte Carlo N‐Particle (MCNP) model for the validation of a prototype backscatter x‐ray (BSX) imager, and optimization of BSX technology for medical applications, including selective object‐plane imaging.

Methods:

BSX is an emerging technology that represents an alternative to conventional computed tomography (CT) and projective digital radiography (DR). It employs detectors located on the same side as the incident x‐ray source, making use of backscatter and avoiding ring geometry to enclose the imaging object. Current BSX imagers suffer from low spatial resolution. A MCNP model was designed to replicate a BSX prototype used for flaw detection in industrial materials. This prototype consisted of a 1.5mm diameter 60kVp pencil beam surrounded by a ring of four 5.0cm diameter NaI scintillation detectors. The imaging phantom consisted of a 2.9cm thick aluminum plate with five 0.6cm diameter holes drilled halfway. The experimental image was created using a raster scanning motion (in 1.5mm increments).

Results:

A qualitative comparison between the physical and simulated images showed very good agreement with 1.5mm spatial resolution in plane perpendicular to incident x‐ray beam. The MCNP model developed the concept of radiography by selective plane detection (RSPD) for BSX, whereby specific object planes can be imaged by varying kVp. 10keV increments in mean x‐ray energy yielded 4mm thick slice resolution in the phantom. Image resolution in the MCNP model can be further increased by increasing the number of detectors, and decreasing raster step size.

Conclusion:

MCNP modelling was used to validate a prototype BSX imager and introduce the RSPD concept, allowing for selective object‐plane imaging. There was very good visual agreement between the experimental and MCNP imaging. Beyond optimizing system parameters for the existing prototype, new geometries can be investigated for volumetric image acquisition in medical applications.

This material is based upon work supported under an Integrated University Program Graduate Fellowship sponsored by the Department of Energy Office of Nuclear Energy.
SU‐C‐209‐06: Improving X‐Ray Imaging with Computer Vision and Augmented Reality
Authors: MacDougall R.D. , Don S , Scherrer B
Published: July 2016

Purpose:

To determine the feasibility of using a computer vision algorithm and augmented reality interface to reduce repeat rates and improve consistency of image quality and patient exposure in general radiography.

Methods:

A prototype device, designed for use with commercially available hardware (Microsoft Kinect 2.0) capable of depth sensing and high resolution/frame rate video, was mounted to the x‐ray tube housing as part of a Philips DigitalDiagnost digital radiography room. Depth data and video was streamed to a Windows 10 PC. Proprietary software created an augmented reality interface where overlays displayed selectable information projected over real‐time video of the patient. The information displayed prior to and during x‐ray acquisition included: recognition and position of ordered body part, position of image receptor, thickness of anatomy, location of AEC cells, collimated x‐ray field, degree of patient motion and suggested x‐ray technique. Pre‐clinical data was collected in a volunteer study to validate patient thickness measurements and x‐ray images were not acquired.

Results:

Proprietary software correctly identified ordered body part, measured patient motion, and calculated thickness of anatomy. Pre‐clinical data demonstrated accuracy and precision of body part thickness measurement when compared with other methods (e.g. laser measurement tool). Thickness measurements provided the basis for developing a database of thickness‐based technique charts that can be automatically displayed to the technologist.

Conclusion:

The utilization of computer vision and commercial hardware to create an augmented reality view of the patient and imaging equipment has the potential to drastically improve the quality and safety of x‐ray imaging by reducing repeats and optimizing technique based on patient thickness.

Society of Pediatric Radiology Pilot Grant; Washington University Bear Cub Fund
SU‐C‐207B‐01: A Novel Graphics Processing Units (GPU) Implementation of Discrete Wavelet Transformation
Authors: Liu A , Chen M , Jiang S , Lu W
Published: July 2016

Purpose:

To design and implement a GPU‐based discrete wavelet transformation (DWT) to be used in medical image reconstruction, image processing, and data compression. DWTs are widely used in medical physics, but the computation of DWTs is time consuming for large volumetric data. An efficient parallel implementation of DWTs is essential for many time sensitive applications, such as 4DCT.

Methods:

We choose Daubechies wavelet transformations as a benchmark, implementing both DWT and inverse DWT (IDWT). The reference CPU code is from “Numerical Recipes in C”. We implemented GPU‐based codes using C++ with CUDA 7.5. A GPU is specialized processors with a highly parallel structure originally designed for manipulating computer graphics. GPU computation is highly memory‐bounded. To optimize GPU memory access pattern and achieve best performance for transformation along Y‐direction, the data are transposed before and after the DWT (IDWT), which can sharply reduce computing efforts. Both CPU and GPU codes are unit‐tested and the result differences between two implementations are verified to be within rounding error. The hardware platform was a desktop with Intel Xeon E5‐1607 3.00 GHz CPU and NVIDIA Quadro K2000 GPU.

Results:

With the GPU implemented code, we process a medical CT image size of 512×512×256 in 0.5 seconds, which is 60 times faster than the CPU implementation. A naive non‐optimized GPU implementation by direct parallelization approaches only 10 times speedup for 2‐D and 3‐D DWT and IDWT. In comparison, the optimization of GPU memory access pattern can obtain an extra 6x speedup.

Conclusion:

We developed an efficient implementation of GPU‐based DWT/IDWT for medical image processing. To achieve the best performance of any medical imaging processing algorithm, developers should pay attention to memory access pattern optimization when implementing on GPU architecture.

This project is supported by CPRIT grant under RP150485.
SU‐D‐BRC‐02: Application of Six Sigma Approach to Improve the Efficiency of Patient‐Specific QA in Proton Therapy
Authors: LAH J , Shin D , Manger R , Kim G
Published: July 2016

Purpose:

To show how the Six Sigma DMAIC (Define‐Measure‐Analyze‐Improve‐Control) can be used for improving and optimizing the efficiency of patient‐specific QA process by designing site‐specific range tolerances.

Methods:

The Six Sigma tools (process flow diagram, cause and effect, capability analysis, Pareto chart, and control chart) were utilized to determine the steps that need focus for improving the patient‐specific QA process. The patient‐specific range QA plans were selected according to 7 treatment site groups, a total of 1437 cases. The process capability index, Cpm was used to guide the tolerance design of patient site‐specific range. We also analyzed the financial impact of this project.

Results:

Our results suggested that the patient range measurements were non‐capable at the current tolerance level of ±1 mm in clinical proton plans. The optimized tolerances were calculated for treatment sites. Control charts for the patient QA time were constructed to compare QA time before and after the new tolerances were implemented. It is found that overall processing time was decreased by 24.3% after establishing new site‐specific range tolerances. The QA failure for whole process in proton therapy would lead up to a 46% increase in total cost. This result can also predict how costs are affected by changes in adopting the tolerance design.

Conclusion:

We often believe that the quality and performance of proton therapy can easily be improved by merely tightening some or all of its tolerance requirements. This can become costly, however, and it is not necessarily a guarantee of better performance. The tolerance design is not a task to be undertaken without careful thought. The Six Sigma DMAIC can be used to improve the QA process by setting optimized tolerances. When tolerance design is optimized, the quality is reasonably balanced with time and cost demands.
SU‐F‐E‐11: Perception and Implementation of Collaborative Documentation Technologies Among Medical Physics Educators and Industry Professionals: A Current Practice Survey
Authors: Johnson Angela N.
Published: July 2016

Purpose:

Collaboration on documents and manuscripts plays a central role in conveying medical physics concepts between interdisciplinary teams, necessary for knowledge‐building, acquiring funding, and translating scientific concepts to applied medical solutions. Conventional tools and emerging internet‐based solutions are used in generating and disseminating physics documents among teams. This research aimed to gain insights on how medical physics professionals and educators are using collaborative documentation software and team practices.

Methods:

An online survey based on a modified version of the Noel & Roberts (2004) collaborative documentation survey in 'Computer Supported Cooperative Work’ was used to collect data from 102 industry practitioners and educators engaged primarily in medical physics. Items includes 30 scaled and qualitative assessments of software use, inputs, time spent on documentation tasks and related activities (meetings, leadership, task assignment, etc.), number of collaborators, documentation volume and practices, revision and publication strategies, and attitudes toward documentation software.

Results:

Of 102 respondents, 74 completed all survey sections, and 58/74 (78%) reported using collaborative document technologies, but only 35% of these were fully satisfied with the technology. A total of 27/58 (47.37%) reported collaborative documentation tools assisted in meeting established deadlines. Most collaborative documentation projects spanned weeks, and required a commitment of 17.68 hours/week (2 – 80, median 15). Between 2–100 synchronous meetings lasting 1–5 hr/meeting were required, most commonly held before starting writing (43.64%) to discuss technical contents (85.96%), document requirements (61.40%), assign tasks (54.39%), or resolve team conflicts (52.63%). Results were presented as a visual infographic, potentially useful as a teaching aid.

Conclusion:

While reportedly easy to use, most online collaborative tools did not fully meet physicist documentation needs, including deficiencies in security, load times, information presentation capabilities, and role assignment. These insights can help improve collaborative documentation software development and training programs for new authors in medical physics fields.

The author is an employee of GE Healthcare. This study was completed through the author's academic doctoral work and no funding or other interests were provided by the author's employer.
SU‐F‐P‐04: Implementation of Dose Monitoring Software: Successes and Pitfalls
Authors: Och J
Published: July 2016

Purpose:

to successfully install a dose monitoring software (DMS) application to assist in CT protocol and dose management.

Methods:

Upon selecting the DMS, we began our implementation of the application. A working group composed of Medical Physics, Radiology Administration, Information Technology, and CT technologists was formed. On‐site training in the application was supplied by the vendor. The decision was made to apply the process for all the CT protocols on all platforms at all facilities. Protocols were painstakingly mapped to the correct masters, and the system went ‘live’.

Results:

We are routinely using DMS as a tool in our Clinical Performance CT QA program. It is useful in determining the effectiveness of revisions to existing protocols, and establishing performance baselines for new units. However, the implementation was not without difficulty. We identified several pitfalls and obstacles which frustrated progress. Including: Training deficiencies, Nomenclature problems, Communication, DICOM variability.

Conclusion:

Dose monitoring software can be a potent tool for QA. However, implementation of the program can be problematic and requires planning, organization and commitment.
SU‐F‐P‐08: Medical Physics Perspective On Radiation Therapy Quality and Safety Considerations in Low Income Settings
Authors: Van Dyk J , Meghzifene A
Published: July 2016

Purpose:

The last few years have seen a significant growth of interest in the global radiation therapy crisis. Various organizations are quantifying the need and providing aid in support of addressing the shortfall existing in many low‐to‐middle income countries (LMICs). The Lancet Oncology Commission report (Lancet Oncol. Sep;16(10):1153‐86, 2015) projects a need of 22,000 new medical physicists in LMICs by 2035 if there is to be equal access globally. With the tremendous demand for new facilities, equipment and personnel, it is very important to recognize quality and safety considerations and to address them directly.

Methods:

A detailed examination of quality and safety publications was undertaken. A paper by Dunscombe (Front. Oncol. 2: 129, 2012) reviewed the recommendations of 7 authoritative reports on safety in radiation therapy and found the 12 most cited recommendations, summarized in order of most to least cited: training, staffing, documentation/standard operating procedures, incident learning, communication/questioning, check lists, QC/PM, dosimetric audit, accreditation, minimizing interruptions, prospective risk assessment, and safety culture. However, these authoritative reports were generally based on input from high income contexts. In this work, the recommendations were analyzed with a special emphasis on issues that are significant in LMICs.

Results:

The review indicated that there are significant challenges in LMICs with training and staffing ranking at the top in terms quality and safety.

Conclusion:

With the recognized need for expanding global access to radiation therapy, especially in LMICs, and the backing by multiple support organizations, quality and safety considerations must be overtly addressed. While multidimensional, training and staffing are top priorities. The use of outdated systems with poor interconnectivity, coupled with a lack of systematic QA in high patient load settings are additional concerns. Any support provided to lower resourced settings must address the multiple facets associated with these quality and safety indicators.
SU‐F‐P‐20: Predicting Waiting Times in Radiation Oncology Using Machine Learning
Authors: Joseph A , Herrera D , Hijal T , Hendren L , Leung A , Wainberg J , Sawaf M , Gorshkov M , Maglieri R , Keshavarz M , Kildea J
Published: July 2016

Purpose:

Waiting times remain one of the most vexing patient satisfaction challenges facing healthcare. Waiting time uncertainty can cause patients, who are already sick or in pain, to worry about when they will receive the care they need. These waiting periods are often difficult for staff to predict and only rough estimates are typically provided based on personal experience. This level of uncertainty leaves most patients unable to plan their calendar, making the waiting experience uncomfortable, even painful. In the present era of electronic health records (EHRs), waiting times need not be so uncertain. Extensive EHRs provide unprecedented amounts of data that can statistically cluster towards representative values when appropriate patient cohorts are selected. Predictive modelling, such as machine learning, is a powerful approach that benefits from large, potentially complex, datasets. The essence of machine learning is to predict future outcomes by learning from previous experience. The application of a machine learning algorithm to waiting time data has the potential to produce personalized waiting time predictions such that the uncertainty may be removed from the patient's waiting experience.

Methods:

In radiation oncology, patients typically experience several types of waiting (eg waiting at home for treatment planning, waiting in the waiting room for oncologist appointments and daily waiting in the waiting room for radiotherapy treatments). A daily treatment wait time model is discussed in this report. To develop a prediction model using our large dataset (with more than 100k sample points) a variety of machine learning algorithms from the Python package sklearn were tested.

Results:

We found that the Random Forest Regressor model provides the best predictions for daily radiotherapy treatment waiting times. Using this model, we achieved a median residual (actual value minus predicted value) of 0.25 minutes and a standard deviation residual of 6.5 minutes. This means that the majority of our estimates are within 6.5 minutes of the actual wait time.

Conclusion:

The goal of this project was to define an appropriate machine learning algorithm to estimate waiting times based on the collective knowledge and experience learned from previous patients. Our results offer an opportunity to improve the information that is provided to patients and family members regarding the amount of time they can expect to wait for radiotherapy treatment at our centre.

AJ acknowledges support by the CREATE Medical Physics Research Training Network grant of the Natural Sciences and Engineering Research Council (Grant number: 432290) and from the 2014 Q+ Initiative of the McGill University Health Centre.
SU‐F‐P‐22: Will the Low Residency Placement Rate Scare Talented Candidates Away from Our Profession?
Authors: Loughery B , Hendrickson K , Burmeister J
Published: July 2016

Purpose:

The low placement rate (∼25%) of medical physics residency match applicants is well‐known to medical physics graduate students, and is beginning to be appreciated by prospective students. We examine this placement rate in detail and its potential impact on future recruitment into our profession based on survey data of both match applicants and program directors.

Methods:

To evaluate and validate residency placement rates, we analyzed annual CAMPEP graduate and residency program reports and data from individual graduate program websites. Programs were excluded if they had no graduates or ambiguous placement statistics. We surveyed medical physics match applicants and directors of CAMPEP‐accredited residency programs to gauge their attitudes toward this placement rate.

Results:

Cumulative data extracted from program websites agreed with CAMPEP reports to within 20 graduates (7% error) and 2 residents (2% error) in 2013. The 2013 residency placement rate was 25.5% for MS and 30.8% for PhD graduates. Overall placement rates range from 0% to 66%. 108 match applicants and 40 program directors responded to the survey. The vast majority of graduates (85.2%) responded that the current residency placement rate is a problem for our profession, compared to only 40% of program directors. More strikingly, 40% of match applicants responded that they would reconsider entering the profession if they had prior knowledge of this residency placement rate.

Conclusion:

Our current residency placement rate presents a bleak picture to prospective students interested in board certified clinical practice. Survey data indicates that this may deter future students from our profession. While our profession seeks solutions, we have an ethical obligation to ensure that incoming students are fully educated about their professional prospects. Moreover, we must evaluate effects of current initiatives on the attractiveness of our education and training infrastructure to prevent the loss of talented future medical physicists.