bluuebunny/crossref_metadata_2025_split huggingface dataset:
A generic structure for plant trait databases
Authors: Kattge Jens , Ogle Kiona , Bönisch Gerhard , Díaz Sandra , Lavorel Sandra , Madin Joshua , Nadrowski Karin , Nöllert Stephanie , Sartor Karla , Wirth Christian 
Published: September 2010

Summary1. Plant traits are fundamental for understanding and predicting vegetation responses to global changes, and they provide a promising basis towards a more quantitative and predictive approach to ecology. As a consequence, information on plant traits is rapidly accumulating, and there is a growing need for efficient database tools that enable the assembly and synthesis of trait data.2. Plant traits are highly heterogeneous, exhibit a low degree of standardization and are linked and interdependent at various levels of biological organization: tissue, organ, plant and population. Therefore, they often require ancillary data for interpretation, including descriptors of the biotic and abiotic environment, methods and taxonomic relationships.3. We introduce a generic database structure that is tailored to accommodate plant trait complexity and is consistent with current theoretical approaches to characterize the structure of observational data. The over‐arching utility of the proposed database structure is illustrated based on two independent plant trait database projects.4. The generic database structure proposed here is meant to serve as a flexible blueprint for future plant trait databases, improving data discovery, and ensuring compatibility among them.
Laparoscopic assisted surgical removal of a congenital rectal hamartoma in a foal
Authors: Salazar T. , Caldwell F. , Joiner K. , Parra‐Sanchez A. , Stewart A. J. 
Published: September 2010

SummaryIn this report we describe a 3‐week‐old Paint horse filly that presented with rectal bleeding associated with a protruding mass. Rectal bleeding in neonates can be caused by infectious agents, trauma, congenital defects, rectal tears or tumours. Histopathology was performed on an avulsed piece of tissue. A second mass was identified endoscopically and was removed using a stapling instrument per rectum under endoscopic guidance and laparoscopic assistance. The mass was diagnosed as a rectal hamartoma. Recovery was uneventful.
Metal artifact suppression from reformatted projections in multislice helical CT using dual‐front active contours
Authors: Li Hua , Yu Lifeng , Liu Xin , Fletcher Joel G. , McCollough Cynthia H. 
Published: September 2010

Purpose:Large metallic implants, such as hip prosthesis and shoulder implants, can cause severe artifacts in CT exams. As such, there have been significant efforts on the design of various image‐ or projection‐based correction methods or iterative reconstruction methods with the hope to reconstruct artifact‐free images. Unfortunately, suppression of metal artifacts remains a very challenging problem, in which metal region segmentation is one of the most important steps in assuring the efficiency of artifact suppression. In this article, the authors propose a novel, semiautomatic metal region segmentation algorithm based on a dual‐front active contour model and a boundary mapping strategy to detect multiple large metal implants on reformatted projection data and to effectively suppress or eliminate metal artifacts on reconstructed images.Methods:First, the projections created from helical scan data were reformatted by combining data at the same view angle over the full longitudinal scan range. In this way, the shape, location, and number of the metal structures show up clearly on each reformatted projection, changing only slightly between adjacent projections. Second, an initial boundary on one of the reformatted projections is defined, and a boundary mapping strategy was utilized to map the metal boundary on the first reformatted projection to the next adjacent projection. Third, a novel dual‐front active contour model was used to evolve the mapped boundary from the prior projection to the actual boundary in the current projection. By iteratively performing the boundary mapping and boundary evolution procedure, the metal structures (one or multiple) on all the projections can be extracted efficiently and accurately. Finally, a Delaunay triangulation was applied to fill the metal shadows and the corrected projection data were reconstructed with a commercially available algorithm.Results:Experimental studies on clinical hip and shoulder CT exams and a comparison with a gradient‐based threshold method were performed. The results demonstrated that the proposed segmentation strategy was able to segment multiple metal implants more accurately than the threshold method. Soft‐tissue visibility was improved dramatically.Conclusions:In total, the artifacts caused by dense metal implants were suppressed dramatically with the proposed metal artifact suppression technique.
Modeling scatter‐to‐primary dose ratio for megavoltage photon beams
Authors: Wang Ken Kang‐Hsin , Zhu Timothy C. 
Published: September 2010

Purpose:A three‐parameter semiempirical model for scatter‐to‐primary dose ratio (SPR) is proposed to fit PDD (or TPR) and beam data. The SPR formula proposed in this study is more accurate than the previously published formula utilizing two parameters, especially for lower energy megavoltage photon beams, because the effect of backscattered photons is now taken into account.Methods:Monte Carlo (MC) calculated SPR for photon energy spectrum between and 24 MV are used to evaluate the accuracy of the models. Based on fitting the MC data, the dependence of the SPR parameters with the attenuation coefficients of the photon beams is obtained and they were incorporated into the authors’ optimization routine. The ability of the optimization routine to fit measured clinic data is examined for photon energies ranging from to 25 MV for all major cobalt and linear accelerator manufacturers.Results:The authors’ model successfully fits the measured photon beam data for field size, where is photon energy in MV and for clinically usable depths, to 20 cm for , to 30 cm for 4 MV, and to 40 cm for 6 MV and higher photon energies. The maximum error among these fits is better than 2% for photon energies above .Conclusions:The new SPR formula, along with the optimization routine, can serve as an efficient tool for performing quality control of x‐ray beam data that conforms to AAPM Radiation Therapy Committee TG40 and Therapy Physics Committee TG142 reports on beam data requirement.
Cascaded analysis of signal and noise propagation through a heterogeneous breast model
Authors: Mainprize James G. , Yaffe Martin J. 
Published: September 2010

Purpose:The detectability of lesions in radiographic images can be impaired by patterns caused by the surrounding anatomic structures. The presence of such patterns is often referred to as anatomic noise. Others have previously extended signal and noise propagation theory to include variable background structure as an additional noise term and used in simulations for analysis by human and ideal observers. Here, the analytic forms of the signal and noise transfer are derived to obtain an exact expression for any input random distribution and the “power law” filter used to generate the texture of the tissue distribution.Methods:A cascaded analysis of propagation through a heterogeneous model is derived for x‐ray projection through simulated heterogeneous backgrounds. This is achieved by considering transmission through the breast as a correlated amplification point process. The analytic forms of the cascaded analysis were compared to monoenergetic Monte Carlo simulations of x‐ray propagation through power law structured backgrounds.Results:As expected, it was found that although the quantum noise power component scales linearly with the x‐ray signal, the anatomic noise will scale with the square of the x‐ray signal. There was a good agreement between results obtained using analytic expressions for the noise power and those from Monte Carlo simulations for different background textures, random input functions, and x‐ray fluence.Conclusions:Analytic equations for the signal and noise properties of heterogeneous backgrounds were derived. These may be used in direct analysis or as a tool to validate simulations in evaluating detectability.
Direct measurement of instantaneous source speed for a HDR brachytherapy unit using an optical fiber based detectora)
Authors: Minamisawa R. A. , Rubo R. A. , Seraide R. M. , Rocha J. R. O. , Almeida A. 
Published: September 2010

Purpose: Several attempts to determine the transit time of a high dose rate (HDR) brachytherapy unit have been reported in the literature with controversial results. The determination of the source speed is necessary to accurately calculate the transient dose in brachytherapy treatments. In these studies, only the average speed of the source was measured as a parameter for transit dose calculation, which does not account for the realistic movement of the source, and is therefore inaccurate for numerical simulations. The purpose of this work is to report the implementation and technical design of an optical fiber based detector to directly measure the instantaneous speed profile of a source in a Nucletron HDR brachytherapy unit.Methods: To accomplish this task, we have developed a setup that uses the Cerenkov light induced in optical fibers as a detection signal for the radiation source moving inside the HDR catheter. As the source travels between two optical fibers with known distance, the threshold of the induced signals are used to extract the transit time and thus the velocity. The high resolution of the detector enables the measurement of the transit time at short separation distance of the fibers, providing the instantaneous speed.Results: Accurate and high resolution speed profiles of the radiation source traveling from the safe to the end of the catheter and between dwell positions are presented. The maximum and minimum velocities of the source were found to be and . The authors demonstrate that the radiation source follows a uniformly accelerated linear motion with acceleration of . In addition, the authors compare the average speed measured using the optical fiber detector to those obtained in the literature, showing deviation up to 265%.Conclusions: To the best of the authors’ knowledge, the authors directly measured for the first time the instantaneous speed profile of a radiation source in a HDR brachytherapy unit traveling from the unit safe to the end of the catheter and between interdwell distances. The method is feasible and accurate to implement on quality assurance tests and provides a unique database for efficient computational simulations of the transient dose.
Normalized metal artifact reduction (NMAR) in computed tomography
Authors: Meyer Esther , Raupach Rainer , Lell Michael , Schmidt Bernhard , Kachelrieß Marc 
Published: September 2010

Purpose:While modern clinical CT scanners under normal circumstances produce high quality images, severe artifacts degrade the image quality and the diagnostic value if metal prostheses or other metal objects are present in the field of measurement. Standard methods for metal artifact reduction (MAR) replace those parts of the projection data that are affected by metal (the so‐called metal trace or metal shadow) by interpolation. However, while sinogram interpolation methods efficiently remove metal artifacts, new artifacts are often introduced, as interpolation cannot completely recover the information from the metal trace. The purpose of this work is to introduce a generalized normalization technique for MAR, allowing for efficient reduction of metal artifacts while adding almost no new ones. The method presented is compared to a standard MAR method, as well as MAR using simple length normalization.Methods:In the first step, metal is segmented in the image domain by thresholding. A 3D forward projection identifies the metal trace in the original projections. Before interpolation, the projections are normalized based on a 3D forward projection of a prior image. This prior image is obtained, for example, by a multithreshold segmentation of the initial image. The original rawdata are divided by the projection data of the prior image and, after interpolation, denormalized again. Simulations and measurements are performed to compare normalized metal artifact reduction (NMAR) to standard MAR with linear interpolation and MAR based on simple length normalization.Results:Promising results for clinical spiral cone‐beam data are presented in this work. Included are patients with hip prostheses, dental fillings, and spine fixation, which were scanned at pitch values ranging from 0.9 to 3.2. Image quality is improved considerably, particularly for metal implants within bone structures or in their proximity. The improvements are evaluated by comparing profiles through images and sinograms for the different methods and by inspecting ROIs. NMAR outperforms both other methods in all cases. It reduces metal artifacts to a minimum, even close to metal regions. Even for patients with dental fillings, which cause most severe artifacts, satisfactory results are obtained with NMAR. In contrast to other methods, NMAR prevents the usual blurring of structures close to metal implants if the metal artifacts are moderate.Conclusions:NMAR clearly outperforms the other methods for both moderate and severe artifacts. The proposed method reliably reduces metal artifacts from simulated as well as from clinical CT data. Computationally efficient and inexpensive compared to iterative methods, NMAR can be used as an additional step in any conventional sinogram inpainting‐based MAR method.
Dose modeling in ultraviolet phototherapy
Authors: Grimes David Robert , Robbins Chris , O'Hare Neil John 
Published: September 2010

Purpose:Ultraviolet phototherapy is widely used in the treatment of numerous skin conditions. This treatment is well established and largely beneficial to patients on both physical and psychological levels; however, overexposure to ultraviolet radiation (UVR) can have detrimental effects, such as erythemal responses and ocular damage in addition to the potentially carcinogenic nature of UVR. For these reasons, it is essential to control and quantify the radiation dose incident upon the patient to ensure that it is both biologically effective and has the minimal possible impact on the surrounding unaffected tissue.Methods:To date, there has been little work on dose modeling, and the output of artificial UVR sources is an area where research has been recommended. This work characterizes these sources by formalizing an approach from first principles and experimentally examining this model.Results:An implementation of a line source model is found to give impressive accuracy and quantifies the output radiation well.Conclusions:This method could potentially serve as a basis for a full computational dose model for quantifying patient dose.
Higher‐order phase shift reconstruction approach
Authors: Cong Wenxiang , Wang Ge 
Published: September 2010

Purpose:Biological soft tissues encountered in clinical and preclinical imaging mainly consists of atoms of light elements with low atomic numbers and their elemental composition is nearly uniform with little density variation. Hence, x‐ray attenuation contrast is relatively poor and cannot achieve satisfactory sensitivity and specificity. In contrast, x‐ray phase‐contrast provides a new mechanism for soft tissue imaging. The x‐ray phase shift of soft tissues is about a thousand times greater than the x‐ray absorption over the diagnostic x‐ray energy range, yielding a higher signal‐to‐noise ratio than the attenuation contrast counterpart. Thus, phase‐contrast imaging is a promising technique to reveal detailed structural variation in soft tissues, offering a high contrast resolution between healthy and malignant tissues. Here the authors develop a novel phase retrieval method to reconstruct the phase image on the object plane from the intensity measurements. The reconstructed phase image is a projection of the phase shift induced by an object and serves as input to reconstruct the 3D refractive index distribution inside the object using a tomographic reconstruction algorithm. Such x‐ray refractive index images can reveal structural features in soft tissues, with excellent resolution differentiating healthy and malignant tissues.Methods:A novel phase retrieval approach is proposed to reconstruct an x‐ray phase image of an object based on the paraxial Fresnel–Kirchhoff diffraction theory. A primary advantage of the authors’ approach is higher‐order accuracy over that with the conventional linear approximation models, relaxing the current restriction of slow phase variation. The nonlinear terms in the autocorrelation equation of the Fresnel diffraction pattern are eliminated using intensity images measured at different distances in the Fresnel diffraction region, simplifying the phase reconstruction to a linear inverse problem. Numerical experiments are performed to demonstrate the accuracy and stability of the proposed approach.Results:The proposed reconstruction formula is a generalization of the transport of intensity equation (TIE). It has the second‐order accuracy compared to the linear model used in the conventional phase retrieval approach. The numerical experiments demonstrate that the accuracy and stability of the proposed phase reconstruction method outperforms the TIE‐based reconstruction method.Conclusions:A novel approach has been proposed to retrieve an x‐ray phase shift image induced by an object from intensity images measured at different distances in the Fresnel diffraction region. The authors’ approach has the second‐order accuracy and is able to retrieve the phase shift of an object stably, overcoming the restriction of slow phase variation assumed by the conventional phase retrieval techniques.
Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams
Authors: Wang Lilie L. W. , Klein David , Beddar A. Sam 
Published: September 2010

Purpose:By using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams.Methods:Three PSDs were modeled in this study: A plastic scintillator (BC‐400) and a scintillating fiber (BCF‐12), both attached by a plastic‐core optical fiber stem, and a plastic scintillator (BC‐400) attached by an air‐core optical fiber stem with a silica tube coated with silver. The authors then calculated, with low statistical uncertainty, the energy and angular dependences of the PSDs’ responses in a water phantom. For energy dependence, the response of the detectors is calculated as the detector dose per unit water dose. The perturbation caused by the optical fiber stem connected to the PSD to guide the optical light to a photodetector was studied in simulations using different optical fiber materials.Results:For the energy dependence of the PSDs in photon beams, the PSDs with plastic‐core fiber have excellent energy independence within about 0.5% at photon energies ranging from 300 keV (monoenergetic) to 18 MV (linac beam). The PSD with an air‐core optical fiber with a silica tube also has good energy independence within 1% in the same photon energy range. For the angular dependence, the relative response of all the three modeled PSDs is within 2% for all the angles in a 6 MV photon beam. This is also true in a 300 keV monoenergetic photon beam for PSDs with plastic‐core fiber. For the PSD with an air‐core fiber with a silica tube in the 300 keV beam, the relative response varies within 1% for most of the angles, except in the case when the fiber stem is pointing right to the radiation source in which case the PSD may over‐response by more than 10%.Conclusions:At ±1% level, no beam energy correction is necessary for the response of all three PSDs modeled in this study in the photon energy ranges from 200 keV (monoenergetic) to 18 MV (linac beam). The PSD would be even closer to water equivalent if there is a silica tube around the sensitive volume. The angular dependence of the response of the three PSDs in a 6 MV photon beam is not of concern at 2% level.
Experimental determination of the radial dose distribution in high gradient regions around wires: Comparison of electron paramagnetic resonance imaging, films, and Monte Carlo simulations
Authors: Kolbun N. , Levêque Ph. , Abboud F. , Bol A. , Vynckier S. , Gallez B. 
Published: September 2010

Purpose:The experimental determination of doses at proximal distances from radioactive sources is difficult because of the steepness of the dose gradient. The goal of this study was to determine the relative radial dose distribution for a low dose rate wire source using electron paramagnetic resonance imaging (EPRI) and to compare the results to those obtained using Gafchromic EBT film dosimetry and Monte Carlo (MC) simulations.Methods:Lithium formate and ammonium formate were chosen as the EPR dosimetric materials and were used to form cylindrical phantoms. The dose distribution of the stable radiation‐induced free radicals in the lithium formate and ammonium formate phantoms was assessed by EPRI. EBT films were also inserted inside in ammonium formate phantoms for comparison. MC simulation was performed using theMCNP4C2 software code.Results:The radical signal in irradiated ammonium formate is contained in a single narrow EPR line, with an EPR peak‐to‐peak linewidth narrower than that of lithium formate ( and 1.4 mT, respectively). The spatial resolution of EPR images was enhanced by a factor of 2.3 using ammonium formate compared to lithium formate because its linewidth is about 0.75 mT narrower than that of lithium formate. The EPRI results were consistent to within 1% with those of Gafchromic EBT films and MC simulations at distances from 1.0 to 2.9 mm. The radial dose values obtained by EPRI were about 4% lower at distances from 2.9 to 4.0 mm than those determined by MC simulation and EBT film dosimetry.Conclusions:Ammonium formate is a suitable material under certain conditions for use in brachytherapy dosimetry using EPRI. In this study, the authors demonstrated that the EPRI technique allows the estimation of the relative radial dose distribution at short distances for a wire source.