bluuebunny/crossref_metadata_2025_split huggingface dataset:
TH‐EF‐BRD‐08: A Retrospective Statistical Analysis of Consistencies in Treatment Plan Parameters by the Treatment Site and Modality
Authors: Liu S , Mao J , Li H , Mutic S , Yang D 
Published: June 2015

Purpose:Simple rules and common senses based on prior knowledge could be powerful tools for medical physicists to identify and prevent severe errors in radiation therapy (RT) treatment plans. However, rules, e.g. the acceptable MU/cGy ratio for different treatment sites, are not yet available quantitatively and therefore cannot be utilized effectively. In this study, we have retrospectively analyzed all the EBRT treatment plans of the past 8 years at authors’ institution. The goal is to better understand the most common treatment plan data statistics, involving MU/cGy ratio, numbers of beams and segments, and ranges of gantry angles for lateral targets, in order to quantitatively define the common sense‐based rules that could be used to guide manual or automatic physics checks.Methods:15844 previous treatment plans were obtained from Mosaiq. Plan data were extensively processed including 1) reducing data size, 2) removing empty and unapproved site and fields, 3) deriving common site names from names of prescriptions and beams that were spelled and misspelled extremely diversely, and 4) removing the plans not covered by this study, e.g. HDR plans. Processed data was then statistically analyzed using multivariate regression algorithms to quantitatively investigate the relationships between the input parameters, i.e. treatment site, technique, modality, and laterality, and the output parameters, i.e. MU/cGy radio, the total number of treatment beams and segments, and the beam gantry angles (only for lateral targets).Results:Mean values and standard deviations of the output parameters were calculated and tabulated per treatment site, technique and modality. Beam gantry angle range and mean gantry angle were analyzed per site for plans treating lateral targets.Conclusion:The results of this study, as the statistics of the major treatment plan parameters, could be useful to quantitatively evaluate the consistency of new treatment plans in either manual or automatic plan checking procedures.
TH‐EF‐BRB‐01: JUNIOR INVESTIGATOR WINNER — Novel EPID for Enhanced Contrast and Detective Quantum Efficiency
Authors: Rottmann J , Morf D , Fueglistaller R , Chen H , Yip S , Star‐Lack J , Zentai G , Berbeco R 
Published: June 2015

Purpose:Beams‐eye‐view imaging applications such as real‐time soft‐tissue motion estimation are hindered by the inherently low image contrast of electronic portal imaging devices (EPID) currently in clinical use. We introduce and characterize a novel EPID that provides substantially increased detective quantum efficiency (DQE), contrast‐to‐noise ratio (CNR) and dynamic range without degradation in spatial resolution.Methods:The prototype design features a stack of four conventional EPID layers combined with low noise integrated readout electronics. Each layer consists of a copper plate, a scintillator (GdO2S2:Tb) and a photodiode/TFT‐switch (aSi:H). We characterize the prototype in terms of contrast‐to‐noise ratio (CNR), modulation transfer function (MTF) and DQE. CNR is estimated using a Las Vegas contrast phantom, presampled MTF is estimated using a slanted edge technique and the DQE is calculated from measured normalized noise power spectra (NPS) and the MTF. The prototype has been designed and built to be interchangeable with the current clinical EPID in terms of size and data output specifications.Results:DQE(0) can be nearly quadrupled to about 4.5% by using the four‐layered design instead of only a single layer device. No substantial differences are observed between each layer's individual MTF and the one for all four layers operating combined indicating that defocusing is negligible. Also, using four layers instead of one nearly doubles (factor x1.9) the CNR showing that the device is mostly quantum noise limited.Conclusion:A layered EPID design allows improving the radiation sensitivity while maintaining spatial resolution and saturation level of a single layer conventional EPID. Experimental characterization of this first 4‐layered prototype demonstrates substantially improved DQE and CNR while maintaining high resolution and remaining quantum noise limited. Besides overall improved image quality and dosimetric sensitivity we anticipate this novel detector design to enable more accurate soft‐tissue motion estimations during radiation therapy procedures, particularly of the lung.The project was partially supported by a grant from Varian Medical Systems, Inc. and grant No. R01CA188446‐01 from the National Cancer Institute. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health.
TH‐EF‐BRB‐04: One‐Pixel Prototype of a Novel Polycrystalline CdTe‐Based Multilayer Detector for Radiation Therapy Imaging Applications
Authors: Shvydka D , Karpov V , Warrell G , Parsai E 
Published: June 2015

Purpose:Recent developments in polycrystalline CdTe‐based photovoltaics have resulted in a technology of inexpensive, large‐area structures possessing strong built‐in fields and superior radiation hardness. Stacking a large number of such structures (number of layers N>>1) into a detector with signal readout from individual layers produces a device with sufficient absorption under an MV beam, low signal spreading, no charge trapping, and low noise due to obviating the need for external biasing. We tested one‐pixel multilayer detector prototypes under a 6MV beam, compared their electrical parameters with those predicted by device modeling, and used the layer number‐signal data for verification of the energy spectrum unfolding algorithm.Methods:We modeled the energy deposition with depth of a CdTe‐based device under a 6MV beam with the Monte Carlo simulation package MCNP5. The results yielded charge carrier generation profiles in individual layers, which were then combined into structures of 10–12 layers. The profiles were used as input for modeling of current‐voltage (I‐V) characteristics with the device operation modeling software SCAPS‐1D. Modeling results were compared to measurements on several 1‐pixel multilayer structures under the 6MV beam of a Varian TrueBeam accelerator.Results:Measurements of I‐V characteristics for all layers of 1‐pixel multilayer structures established electrical parameters of best devices to be close to those modeled. A regularization algorithm for extracting the energy spectrum was successfully tested with these structures.Conclusion:The proposed multilayer structure adds a third dimension, depth‐signal reading, to the traditional 2‐D pixelation, allowing for the photon energy and source position to be obtained through signal processing. The latter processing relies on regularization approaches, similar to those developed for computed tomography, and thus have potential to significantly improve the quality of images under MV energy x‐ray sources of medical linear accelerators.This research is supported with NRC grant No. NRC‐HQ‐12‐G‐38‐0042
TH‐EF‐BRB‐05: Dynamic Blade Collimation for Image Quality Improvement and Dose Reduction in CBCT Guidance
Authors: Parsons D , Robar J 
Published: June 2015

Purpose:The focus of this work is the development of a novel blade collimation system enabling volume‐of‐interest (VOI) CBCT using the kV source on a TrueBeam linear accelerator (linac). Advantages of the system are assessed, particularly with regard to reduction and localization of dose, as well as improvement of image quality.Methods:A four blade dynamic kV collimator was developed to track a VOI during a CBCT acquisition. The system is controlled using a Raspberry Pi computer placed within the linac gantry. The current prototype is capable of tracking an arbitrary volume defined by the treatment planner for subsequent CBCT guidance. During gantry rotation, the collimator tracks the VOI with adjustment of position and dimension. CBCT image quality was investigated as a function of collimator dimension, while maintaining the same dose to the VOI, for a 20 cm diameter cylindrical water phantom with a 9 mm diameter bone insert centered on isocenter. Dose distributions for various anatomical sites were modeled using a dynamic BEAMnrc library and DOSXYZnrc. The resulting VOI dose distributions were compared to full‐field distributions to quantify dose reduction and localization to the target volume.Results:Preliminary measurements show contrast increase by a factor of 1.3 and noise reduction by a factor of 1.7, for CBCT. This results in a increase in contrast‐to‐noise ratio by a factor of approximately 2.2. Depending upon the anatomical site, dose was reduced to 15%–80% of the full field value along the central axis plane and down to less than 1% along the axial planes.Conclusion:The present system allows CBCT imaging of a planner‐defined volume, offering both image quality improvement and reduction of imaging dose for the patient. Current work involves the development of fluence modulation for VOI CBCT.This work was supported through a research partnership with Varian Medical, Incorporated.
TH‐EF‐BRA‐02: Patient‐Specific Dose Maps for CT Scans Using a Fast, Deterministic Boltzmann Transport Equation Solver
Authors: Wang A , Maslowski A , Wareing T , Schmidt T , Star‐Lack J 
Published: June 2015

Purpose:To develop a rapid and accurate software tool for computing patient‐specific radiation dose maps of dose delivered from kV computed tomography (CT) scans.Methods:Monte Carlo methods currently provide the gold‐standard for calculating patient‐specific dose maps, but require immense computational resources to achieve sufficiently high statistical accuracy. To overcome this limitation, a deterministic method was implemented to solve the same underlying Boltzmann transport equation (BTE) that governs particle interactions and transport. Phase‐space was discretized according to spatial location, energy, and angle, and a deterministic finite element algorithm was applied to compute the object's photon fluence distribution, which does not exhibit stochastic noise. A computationally efficient GPU implementation for a standard workstation was developed, and comparison was made between the performance of the deterministic BTE solver and a standard Monte Carlo algorithm for a cone‐beam projection of a virtual anthropomorphic chest phantom.Results:The BTE solution and Monte Carlo results were in strong agreement with a relative root‐mean square error (RMSE) of 3.47%. Some larger differences existed at high‐contrast boundaries (e.g., air/water) and within the bone, and are under further investigation. Notably, the computation time of the BTE solver was 8 seconds, while to obtain the same level of statistical uncertainty with conventional Monte Carlo required 1200 CPU‐hours. Additionally, unlike Monte Carlo, the BTE computation time is only weakly dependent on the number of sources, making it extremely well‐suited for CT dose calculations. Therefore, the BTE‐based method is expected to offer a >30,000x speed increase compared to Monte Carlo for entire CT scans, even after application of variance reduction techniques and GPU implementation.Conclusion:The novel deterministic BTE solver offers a significantly faster alternative to Monte Carlo‐based methods for computing dose delivered by CT scans, which can enable estimation of patient‐specific organ doses for each CT examination performed.Adam Wang, Alex Maslowski, Todd Wareing, and Josh Star‐Lack are employees of Varian Medical Systems.
TH‐F‐304‐00: Task Group 158: Measurement and Calculation of Doses Outside the Treatment Volume From External‐Beam Radiation Therapy Treatment
Authors: Howell Rebecca 
Published: June 2015

The introduction of advanced techniques and technology in radiotherapy has greatly improved our ability to deliver highly conformal tumor doses while minimizing the dose to the adjacent organs at risk. Despite these tremendous improvements there remains a general concern about doses to normal tissues outside the target volume. As patients live longer after treatment, there is increased opportunity for late effects including second cancers and cardiac toxicity to manifest. Complicating the management of these issues, there are unique challenges with measuring, calculating, and reducing non‐target doses that many medical physicists may have limited experience with. Task Group (TG) 158, measurement and calculation of doses outside the treatment volume from external‐beam radiation therapy was created to provide guidance for physicists in terms of assessing and managing non‐target doses. This education session would highlight the major topics included TG‐158.The principal objective for this session will be to provide guidance for medical physicists in terms of assessing and managing non‐target doses.Learning Objectives:

To highlight major concerns with non‐target radiation and provide a rough estimate of doses associated with different treatment approaches in clinical practice.
To discuss (a) uses of dosimeters and phantoms for measuring photon, electron, and neutron doses and (b) the use of calculation techniques (including Monte Carlo) for dosimetric evaluations.
To highlight techniques that may be considered for reducing non‐target doses and summarize TG158 recommendations for both clinical and research practice.
TH‐F‐304‐01: Dosimeters and Phantoms for Measuring Non‐Target Photon, Electron, and Neutron Doses
Authors: Howell R. 
Published: June 2015

The introduction of advanced techniques and technology in radiotherapy has greatly improved our ability to deliver highly conformal tumor doses while minimizing the dose to the adjacent organs at risk. Despite these tremendous improvements there remains a general concern about doses to normal tissues outside the target volume. As patients live longer after treatment, there is increased opportunity for late effects including second cancers and cardiac toxicity to manifest. Complicating the management of these issues, there are unique challenges with measuring, calculating, and reducing non‐target doses that many medical physicists may have limited experience with. Task Group (TG) 158, measurement and calculation of doses outside the treatment volume from external‐beam radiation therapy was created to provide guidance for physicists in terms of assessing and managing non‐target doses. This education session would highlight the major topics included TG‐158.The principal objective for this session will be to provide guidance for medical physicists in terms of assessing and managing non‐target doses.Learning Objectives:

To highlight major concerns with non‐target radiation and provide a rough estimate of doses associated with different treatment approaches in clinical practice.
To discuss (a) uses of dosimeters and phantoms for measuring photon, electron, and neutron doses and (b) the use of calculation techniques (including Monte Carlo) for dosimetric evaluations.
To highlight techniques that may be considered for reducing non‐target doses and summarize TG158 recommendations for both clinical and research practice.
TH‐F‐304‐02: Overview of Non‐Target Doses, Concerns, and Summary of Recommendations
Authors: Kry S. 
Published: June 2015

The introduction of advanced techniques and technology in radiotherapy has greatly improved our ability to deliver highly conformal tumor doses while minimizing the dose to the adjacent organs at risk. Despite these tremendous improvements there remains a general concern about doses to normal tissues outside the target volume. As patients live longer after treatment, there is increased opportunity for late effects including second cancers and cardiac toxicity to manifest. Complicating the management of these issues, there are unique challenges with measuring, calculating, and reducing non‐target doses that many medical physicists may have limited experience with. Task Group (TG) 158, measurement and calculation of doses outside the treatment volume from external‐beam radiation therapy was created to provide guidance for physicists in terms of assessing and managing non‐target doses. This education session would highlight the major topics included TG‐158.The principal objective for this session will be to provide guidance for medical physicists in terms of assessing and managing non‐target doses.Learning Objectives:

To highlight major concerns with non‐target radiation and provide a rough estimate of doses associated with different treatment approaches in clinical practice.
To discuss (a) uses of dosimeters and phantoms for measuring photon, electron, and neutron doses and (b) the use of calculation techniques (including Monte Carlo) for dosimetric evaluations.
To highlight techniques that may be considered for reducing non‐target doses and summarize TG158 recommendations for both clinical and research practice.
TH‐F‐304‐03: Calculation Techniques (including Monte Carlo) for Determining Non‐Target Photon, Electron, and Neutron Doses
Authors: Bednarz B. 
Published: June 2015

The introduction of advanced techniques and technology in radiotherapy has greatly improved our ability to deliver highly conformal tumor doses while minimizing the dose to the adjacent organs at risk. Despite these tremendous improvements there remains a general concern about doses to normal tissues outside the target volume. As patients live longer after treatment, there is increased opportunity for late effects including second cancers and cardiac toxicity to manifest. Complicating the management of these issues, there are unique challenges with measuring, calculating, and reducing non‐target doses that many medical physicists may have limited experience with. Task Group (TG) 158, measurement and calculation of doses outside the treatment volume from external‐beam radiation therapy was created to provide guidance for physicists in terms of assessing and managing non‐target doses. This education session would highlight the major topics included TG‐158.The principal objective for this session will be to provide guidance for medical physicists in terms of assessing and managing non‐target doses.Learning Objectives:

To highlight major concerns with non‐target radiation and provide a rough estimate of doses associated with different treatment approaches in clinical practice.
To discuss (a) uses of dosimeters and phantoms for measuring photon, electron, and neutron doses and (b) the use of calculation techniques (including Monte Carlo) for dosimetric evaluations.
To highlight techniques that may be considered for reducing non‐target doses and summarize TG158 recommendations for both clinical and research practice.
Use of the mCherry Fluorescent Protein To Study Intestinal Colonization by Enterococcus mundtii ST4SA and Lactobacillus plantarum 423 in Mice
Authors: van Zyl Winschau F. , Deane Shelly M. , Dicks Leon M. T. 
Published: June 2015

ABSTRACT

Lactic acid bacteria (LAB) are natural inhabitants of the gastrointestinal tract (GIT) of humans and animals, and some LAB species receive considerable attention due to their health benefits. Although many papers have been published on probiotic LAB, only a few reports have been published on the migration and colonization of the cells in the GIT. This is due mostly to the lack of efficient reporter systems. In this study, we report on the application of the fluorescent mCherry protein in the
in vivo
tagging of the probiotic strains
Enterococcus mundtii
ST4SA and
Lactobacillus plantarum
423. The
mCherry
gene, encoding a red fluorescent protein (RFP), was integrated into a nonfunctional region on the genome of
L. plantarum
423 by homologous recombination. In the case of
E. mundtii
ST4SA, the
mCherry
gene was cloned into the pGKV223D LAB/
Escherichia coli
expression vector. Expression of the
mCherry
gene did not alter the growth rate of the two strains and had no effect on bacteriocin production. Both strains colonized the cecum and colon of mice.
Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State
Authors: Weller Daniel , Wiedmann Martin , Strawn Laura K. 
Published: June 2015

ABSTRACT

While rain and irrigation events have been associated with an increased prevalence of foodborne pathogens in produce production environments, quantitative data are needed to determine the effects of various spatial and temporal factors on the risk of produce contamination following these events. This study was performed to quantify these effects and to determine the impact of rain and irrigation events on the detection frequency and diversity of
Listeria
species (including
L. monocytogenes
) and
L. monocytogenes
in produce fields. Two spinach fields, with high and low predicted risks of
L. monocytogenes
isolation, were sampled 24, 48, 72, and 144 to 192 h following irrigation and rain events. Predicted risk was a function of the field's proximity to water and roads. Factors were evaluated for their association with
Listeria
species and
L. monocytogenes
isolation by using generalized linear mixed models (GLMMs). In total, 1,492 (1,092 soil, 334 leaf, 14 fecal, and 52 water) samples were collected. According to the GLMM, the likelihood of
Listeria
species and
L. monocytogenes
isolation from soil samples was highest during the 24 h immediately following an event (odds ratios [ORs] of 7.7 and 25, respectively). Additionally,
Listeria
species and
L. monocytogenes
isolates associated with irrigation events showed significantly lower
sigB
allele type diversity than did isolates associated with precipitation events (
P
= <0.001), suggesting that irrigation water may be a point source of
L. monocytogenes
contamination. Small changes in management practices (e.g., not irrigating fields before harvest) may therefore reduce the risk of
L. monocytogenes
contamination of fresh produce.
Functional Analysis of Sterol Transporter Orthologues in the Filamentous Fungus Aspergillus nidulans
Authors: Bühler Nicole , Hagiwara Daisuke , Takeshita Norio 
Published: June 2015

ABSTRACTPolarized growth in filamentous fungi needs a continuous supply of proteins and lipids to the growing hyphal tip. One of the important membrane compounds in fungi is ergosterol. At the apical plasma membrane ergosterol accumulations, which are called sterol-rich plasma membrane domains (SRDs). The exact roles and formation mechanism of the SRDs remained unclear, although the importance has been recognized for hyphal growth. Transport of ergosterol to hyphal tips is thought to be important for the organization of the SRDs. Oxysterol binding proteins, which are conserved from yeast to human, are involved in nonvesicular sterol transport. InSaccharomyces cerevisiaeseven oxysterol-binding protein homologues (OSH1 to -7) play a role in ergosterol distribution between closely located membranes independent of vesicle transport. We found five homologous genes (oshAtooshE) in the filamentous fungiAspergillus nidulans. The functions of OshA-E were characterized by gene deletion and subcellular localization. Each gene-deletion strain showed characteristic phenotypes and different sensitivities to ergosterol-associated drugs. Green fluorescent protein-tagged Osh proteins showed specific localization in the late Golgi compartments, puncta associated with the endoplasmic reticulum, or diffusely in the cytoplasm. The genes expression and regulation were investigated in a medically important speciesAspergillus fumigatus, as well asA. nidulans. Our results suggest that each Osh protein plays a role in ergosterol distribution at distinct sites and contributes to proper fungal growth.