bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of trichomes in the Abutilon nectary gland
Authors: Kronestedt E. C. , Robards A. W. , Stark M. , Olesen P.
Published: August 2010

Nectary trichomes of Abutilon striatum var. thompsonii arise by sequential periclinal divisions of outpushings from epidermal cells so producing trichomes that, when mature, are about 12 cells long. All epidermal cells within the nectary undergo this transformation. Later, anticlinal divisions lead to a multiseriate lower part of the trichome. The original epidermal cell becomes the basal cell which increases substantially in volume during development, thus leading to lateral separation of the trichomes. Above the basal cell is the stalk cell which develops an apoplastic barrier in its anticlinal (outer) wall. Secretion ultimately takes place from a capitate tip cell. An initially very thin cuticular layer, which overlies the whole trichome, eventually becomes as thick as the cell wall itself (approx. 0.4 μm). The pre‐secretory hairs contain numerous small, condensed mitochondria; poorly differentiated plastids; dictyosomes with coated vesicles; small vacuoles; and a large amount of smooth endoplasmic reticulum (“secretory reticulum”) which contrasts with the rough endoplasmic reticulum seen during earlier developmental stages. As secretion proceeds, vacuolation becomes more extensive. Plasmodesmata are present between all the cells of the trichome and diminish in frequency from about 12.0 μm‐2 in the stalk cell to about 4.0 μm‐2 in the apical cells. This variation in plasmodesmatal frequency along the trichome is seen at all stages of development. The ultrastructural evidence would be consistent with the hypothesis that the pre‐nectar flows through the plasmodesmata from cell to cell, is loaded into a “secretory compartment”, and is then unloaded into the apoplast from all cells of the trichome distal to the stalk cell.
Thelocarpon cyaneum sp. nov.
Authors: Olech Maria , Alstrup Vagn
Published: August 2010

Thelocarpon cyaneum, a new lichenicolous fungus onPolyblastia, is described from Antarctica.
Family, Friends, and Personal Communities: Changing Models‐in‐the‐Mind
Authors: Pahl Ray , Spencer Liz
Published: August 2010

Models‐in‐the‐minds about the proper and right way to be a true friend or to “do” family behavior may not necessarily fit lived experience, especially in cases where relationships become fused and distinctions between family and friend become blurred. We suggest the idea of a personal community—the microsocial world of significant others for any given individual—as a practical schema for capturing the set of relationships in which people are actually embedded.
Redistribution with Growth—a reply*
Authors: Jolly Richard
Published: August 2010

SUMMARY Although Colin Leys argues that Redistribution with Growth is directed against revolutionary change, this article shows the charge to be unjustified. The quantitative models which the IBRD/IDS volume develops to analyse distribution and growth, and the basic strategies considered, are as equally applicable to socialist as to capitalist transformations. It is not RwG which rules out radical change—it is rather Colin Leys who attempts to rule out serious consideration of what might be done to alleviate poverty and improve income distribution when radical change appears very unlikely. This article elaborates these points, beginning with a summary of the basic argument of RwG and concluding with an alternative statement of the weaknesses in RwG and of fruitful directions for future work and refinement.

RESUME Redistribution avec croissance—une réponse

Quoique Colin Leys soutienne que Redistribution avec croissance est dirigé contre le changement révolutionnaire, cette analyse peut se voir reprocher d'ètre injustifiée. Les modèles quantitatifs que le volume IBRD/IDS développe pour analyser la distribution avec croissance et les stratégies de base qui sont évaluées sont tout aussi bien applicables à des transformations socialistes que capitalistes. Ce n'est pas le RAC qui détermine le changement radical—mais c'est plutôt Colin Leys qui tente d'établir à quel point il est nécessaire de prendre en considération ce qui devrait être fait pour alléger la pauvreté et améliorer la distribution du revenu lorsque le changement radical parait très improbable. Cet article élabore ces points en commençant par un résumé de I'argument de base du RAC et en concluant par une affirmation portant à la fois sur les faiblesses dans le RAC et les directions fructueuses pour le travail futur.

RESUMEN Redistribución con Crecimiento—una Réplica

Aunque Colin Leys sostiene que Redistribución con Crecimiento está dirigido contra el cambio revolucionario, este artículo muestra que el cargo es injustificado. Los modelos cuantitativos que el volumen del IBRD/IDS desarrolla para analizar la distribución el crecimiento, las estrategias básicas consideradas, son igualmente aplicables tanto a las transformaciones capitalistas como a las socialistas. No es RCC el que descarta un cambio radical, sino más bien Colin Leys el que descarta toda consideración seria de lo que podría hacerse para aliviar la pobreza mejorar la distribución del ingreso, cuando un cambio radical aparece altamente improbable. Este artículo desarrolla estos puntos, comenzando con un resumen del argumento básico de RCC, para concluir con una exposición sobre las debilidades de RCC los lineamientos fructíferos para un trabajo un refinamiento futuros.
Administrative Training: Doublethink and Newspeak
Authors: Minogue Martin
Published: August 2010

Summary Administrative training is a growth industry, and has developed a philosophy and practice. The philosophy consists of claims about the purposes and results of training which the practice cannot substantiate. Those involved in the ‘industry’ are aware of this, and resist real evaluation of their claims, which consist essentially in using the expansionist philosophy of training to create or justify personal or institutional benefits. The costs of this ‘double‐think’ strategy are not defined. Instead, a special language is deliberately constructed to avoid precise meaning: a form of ‘newspeak’, which reduces the possibilities for effective debate of issues which deserve penetrating reappraisal.

Resume Formation administrative: “Doublethink” et “New‐speak”

La formation administrative est une industrie en croissance et a donné naissance à une doctrine et à une pratique. La doctrine consiste en des affirmations sur les objectifs et les résultats de la formation que la pratique ne peut justifier. Tous ceux qui sont dans cette “industrie” s'en rendent compte et refusent une réelle évaluation de leurs affirmations qui consistent essentiellement à utiliser la doctrine expansionniste de la formation pour créer et justifier les bénéfices personnels et institutionnels. Le prix de cette stratégie de “doublethink” n'est pas déterminé. Mais au contraire, un langage spécial est délibérément créé pour éviter un sens trop précis: une forme de “newspeak” qui réduit la possibilité de débattre efficacement des problèmes qui demandent à être réévalués.

Resumen Formación Administrativa: “Doublethink” y “New‐speak”

La formación administrativa es una industria en crecimiento y ha desarrollado una filosofía y una práctica. La filosofía consiste en pretensiones sobre los propósitos y los resultados de la formación que no se pueden cristalizar en la práctica. Los que intervienen en la industria están conscientes de esto y resisten la evaluación real de sus pretensiones, que fundamentalmente consisten en usar la filosofía expansionista de la formación para crear o justificar beneficios personales o institucionales. No se determinan los costos de esta estrategia de “doublethink”. En cambio, se ha creado deliberadamente un lenguage especial para evitar los significados precisos: una forma de “newspeak” que reduce las posibilidades de debate eficaz sobre temas que merecen una nueva evaluación penetrante.
Electronics and the Technology Gap—the Case of Numerically Controlled Machine Tools
Authors: Jacobsson Staffan
Published: August 2010

SUMMARY This article is concerned with the introduction of electronic control devices (‘numerical controls’) in machine tools. This has provided substantial benefits to firms in that it saves both capital and labour, improves product quality and reduces the time required to bring new products onto the market. Whilst these advantages may appear to benefit developed countries disproportionately, the most significant benefit conferred is probably in relation to the saving of skilled labour. Since skilled labour is the major element in the developed countries' comparative advantage, it is likely that the diffusion ot these machine tools will move comparative advantage in favour of the newly industrialising countries (NICs). However, the article concludes with the warning that advances in automation technology will probably reduce this temporary shift.

RESUME L'électronique et le fossé technologique: le cas des machines‐outils à commande numérique

Cet article concerne l'introduction de dispositifs de commande numérique sur les machines‐outils. Les avantages: économies de capital et de main‐d'oeuvre, amélioration de la qualité et déduction des délais de production. Ils paraissent donner aux pays développés plusieurs longueurs d'avance, mais le principal est l'économie de main‐d'oeuvre qualifiée. Puisque cet élément est le plus important des avantages des pays développés, il est probable que la diffusion de ces machines‐outils profite surtout aux pays d'industrialisation récente. L'article conclut cependant que les progrès de l'automation finiront par compenser probablement cette évolution temporaire.

RESUMEN La electrónica y las diferencias tecnológicas: el caso de las máquinas‐herramienta de control numérico

Este artículo se concentra en la introducción de los dispositivos de control electrónico (‘controles numéricos’) en las máquinas‐herramienta. Esto ha proporcionado beneficios importantes a las empresas porque ahorra tanto capital como mano de obra, mejora la calidad del producto y reduce el tiempo necesario para introducir nuevos productos en el mercado. Aunque estas ventajas parezcan beneficiar a los países desarrollados de una manera desproporcionada, el beneficio más importante que se obtiene está probablemente relacionado con el ahorro de mano de obra especializada. Como le mano de obra especializada es el elemento más importante en la ventaja comparativa de los países desarrollados, es probable que la divulgación de estas máquinas‐herramienta traslade esta ventaja comparativa en favor de los países recientemente industrializados. No obstante, el artículo concluye con un aviso de que los progresos realizados en la tecnología automatizada probablemente reducirá este cambio provisional.
Europe and the South in the 1980s: prospects for political change
Authors: Ramphal Shridath S.
Published: August 2010

SUMMARY The USA may be withdrawing from active involvement in North‐South issues. Europe, too, has dragged its feet in the various North‐South fora. Yet the challenge of the South is growing, and is evident in figures on debt, deteriorating terms of trade and protectionism. The EEC has a major role to play in reversing the deterioration of North‐South relations. The Community, in particular, has more interest in the Third World than do some of the member states. It should build on the on the Lomé framework, and move out to other Third World countries.

RESUMEN Europa y el Sur en la década 1980

Estados Unidos puede retirarse del compromiso activo en los asuntos Norte‐Sur y también Europa ha perdido interés en los diversos foros sobre el tema. No obstante, el desafío del Sur está creciendo y se hace evidente en las cifras de la deuda, el deterioro de los términos de intercambio y el proteccionismo. La CEE tiene un importante rol que cumplir en revertir el deterioro de las relaciones Norte‐Sur. La Comunidad, en especial, tiene más interés en el Tercer Mundo que algunos de los estados miembros y debería basarse en el marco de Lomé y orientarse a otros países del Tercer Mundo.

RÉSUMÉ L'Europe et le Sud dans les années 80

Les Etats‐Unis envisageraient un retrait de leur participation active dans les problèmes Nord‐Sud. L'Europe aussi a été lente à réagir dans les divers forums Nord‐Sud. Cependant le défi du Sud s'accroît, et cela est évident dans les chiffres des dettes, détériorant les conditions du commerce et du protectionnisme. La CEE a un rôle majeur à jouer dans le retournement de la situation de détérioration des relations Nord‐Sud. La Communauté, en particulier, a plus d'intérêts dans le Tiers‐Monde que certains états‐membres. Elle devrait mettre en place le projet de Lomé, et se tourner vers d'autres pays du Tiers‐Monde.
Front Tracking Based Macroscopic Calculations of Columnar and Equiaxed Solidification of a Binary Alloy
Authors: Seredyński M. , Banaszek J.
Published: August 2010

The paper explores the potential of a recently developed special front tracking method in the identification of the interface between columnar and equiaxed structures formed during a binary alloy solidification, driven by thermosolutal convection. The method, based on theoretical and experimental dendrite tip kinetics, is capable of directly distinguishing between the columnar mush and the undercooled liquid/equiaxed region developing ahead of the dendrite tip curve. A new numerical model and its computational algorithm are proposed, where the classical Eulerian volume averaged description of the transport processes is coupled with the Lagrangian front tracking method on a fixed control-volume grid. Having thus distinguished zones of different dendrite structures, distinct simulation models are used within each of the zones, e.g., the Darcy’s porous medium model in the stationary dendrite region, and a model of slurry with floating dendrites in the equiaxed part of the mush. The calculated temperature and solute concentration fields are compared with the relevant results of the classical enthalpy-porosity model, for an example problem of Pb-48 wt % Sn alloy solidification driven by diffusion and thermosolutal convection. And a good match with both solutions is exhibited. A preliminary validation study is also presented by comparing the available experimental data with the model predictions. Possible reasons for some observed discrepancies between the calculations and the experimental findings are discussed. Finally, the proposed front tracking approach is used to address the question of the impact of dendrites floating in the liquid on the flow pattern and macrosegregation in the solidifying alloy.
Natural Convection in a Partially Heat Generating Rod Bundle Inside an Enclosure
Authors: Krishna D. Jaya , Thansekhar M. R. , Venkateshan S. P. , Basak Tanmay , Das Sarit K.
Published: August 2010

Buoyancy induced flows in a partially heat generating rod bundle enclosed inside a tall cavity are investigated. First, a detailed experimental study is carried out, and the thermal hydraulics is analyzed at different power inputs and boundary cooling rates of the enclosure. Later, a generalized non-Darcy simulation is developed using a heat generating orthotropic porous media approach and is compared with the experimental results. The results of a numerical simulation for natural convection in enclosed partially heat generating rod bundles satisfactorily predict the temperature distribution within the rod bundle. Finally, a parametric study is carried out by varying the porosity (pitch to diameter ratio of the rod bundle) of the considered enclosure for the understanding of flow physics and heat transfer in such applications.
Forced Flow of Vapor Condensing Over a Horizontal Plate (Problem of Cess and Koh): Steady and Unsteady Solutions of the Full 2D Problem
Authors: Kulkarni S. , Narain A. , Mitra S.
Published: August 2010

Accurate steady and unsteady numerical solutions of the full 2D governing equations—which model the forced film condensation flow of saturated vapor over a semi-infinite horizontal plate (the problem of Cess and Koh)—are obtained over a range of flow parameters. The results presented here are used to better understand the limitations of the well-known similarity solutions given by Koh. It is found that steady/quasisteady filmwise solution exists only if the inlet speed is above a certain threshold value. Above this threshold speed, steady/quasisteady film condensation solutions exist and their film thickness variations are approximately the same as the similarity solution given by Koh. However, these steady solutions differ from the Koh solution regarding pressure variations and associated effects in the leading part of the plate. Besides results based on the solutions of the full steady governing equations, this paper also presents unsteady solutions that characterize the steady solutions’ attainability, stability (response to initial disturbances), and their response to ever-present minuscule noise on the condensing-surface. For this shear-driven flow, the paper finds that if the uniform vapor speed is above a threshold value, an unsteady solution that begins with any reasonable initial-guess is attracted in time to a steady solution. This long time limiting solution is the same—within computational errors—as the solution of the steady problem. The reported unsteady solutions that yield the steady solution in the long time limit also yield “attraction rates” for nonlinear stability analysis of the steady solutions. The attraction rates are found to diminish gradually with increasing distance from the leading edge and with decreasing inlet vapor speed. These steady solutions are generally found to be stable to initial disturbances on the interface as well as in any flow variable in the interior of the flow domain. The results for low vapor speeds below the threshold value indicate that the unsteady solutions exhibit nonexistence of any steady limit of filmwise flow in the aft portion of the solution. Even when a steady solution exists, the flow attainability is also shown to be difficult (because of waviness and other sensitivities) at large downstream distances.
SU‐BB‐201B‐03: The AAPM Resources for Continuing Education ‐ Increasing Effectiveness for the Future
Authors: Limmer J
Published: August 2010

This presentation will include a discussion of the resources available in the Virtual Library, the opportunities for Continuing Education and SAMs credits on‐line, and actions planed or underway to increase the overall effectiveness in meeting the CE/SAMs needs of the membership.

Learning Objectives:

1. The existing resources in the AAPM Virtual Library

2. The current opportunities for CE and SAMs on line through AAPM

3. The plans for future developments in meeting the CE needs of membership through on‐line educational experiences.
SU‐GG‐E‐02: Radiology Residents Performance on Physics Examinations
Authors: Huda W , Frey G , Petrone T , Magill D
Published: August 2010

Purpose To quantify radiology resident performance on radiological physics examinations, and investigate how this performance varies temporally. Method and Materials We analyzed results of online physics examinations consisting of 120 multiple choice questions covering all of radiological physics. In 2007, results were obtained for 121 residents in the eight week period immediately prior to the written ABR Physics examination. In 2008, results were obtained for 145 residents in the two week period immediately prior to the ABR Physics examination. The scores are presented as the absolute number of correct answers out of the 120 questions, where one of the five options was correct. Results In 2007, the median score increased from 59 when the examinations were taken eight weeks prior to the ABR examination, to 81 when taken less than two weeks prior to the ABR examination. The 15th/85th percentile values showed similar increases from 41/69 at “eight weeks” to 67/94 at less than “two weeks”. In 2008, the median score for all residents was 81. Corresponding scores for selected percentiles were 58 (10th percentile), 74 (30th percentile), 88 (70th percentile) and 96 (90th percentile). Conclusion Radiology resident scores on Physics Examinations increase dramatically (i.e., > 50%) over a two month period immediately prior the ABR Physics examination. The median score on a Physics Examination for residents taking the ABR examination is about 65%. Historical data suggest that the bottom 15% of Radiology Residents fail their written ABR Physics examination, implying a score greater than 55% to pass.
SU‐GG‐I‐01: Two‐View CAD Performance in Digital Mammography
Authors: Kallergi M , Vourtsi A
Published: August 2010

Purpose: To compare the sensitivity and specificity of a CAD system for identifying breast cancer in two digital mammographic views. Method and Materials: A commercial CAD system was applied retrospectively to craniocaudal (CC) and mediolateral oblique (MLO) views of 90 patients with 45 histologically proven cancers and 45 benign findings also confirmed histologically or with ultrasound and follow‐up. Cancers included 21 masses and 24 microcalcification clusters. Benign findings included 23 masses and 22 calcifications. The sensitivity and specificity of the CAD system for cancer detection was estimated for each view separately and for the combination of the two views. The paired t test was used for statistical analysis.Results: The sensitivities of the CAD system were 93% in the CC view and 89% in the MLO view. Sensitivity was higher (95%) when views were combined. The sensitivity for masses was significantly smaller than the sensitivity for calcifications (about 15% lower) but it increased significantly when the CAD results from the two views were combined (from an average 74% in the single views to 90%). The specificity of the CAD system was 32% for masses and 28% for the calcifications and it was only estimated from the single view findings.Conclusion: In agreement with prior reports, the commercial CAD system showed sensitivities independent of the type of view for both masses and calcifications. The sensitivity for masses was smaller than the calcifications but increased to similar levels when the detections in both views were considered. The specificity of the system was low indicating the need for integrating a more robust classification algorithm in the detection process.
SU‐GG‐I‐129: Impact of Varying the Number of Projection Images Used in Digital Tomosynthesis on the Effective Slice Thickness of the Tomograms
Authors: Sarkar V , Wang B , Rassiah‐Szegedi P , Szegedi M , Huang Y , Zhao H , Salter B
Published: August 2010

Purpose: To investigate the effect of changing the number of projections within set tomosynthesis angles on the final effective slice thickness of the reconstructed tomograms. Method and Materials: For several tomosynthesis angles, varying numbers of images were sampled from a set of projections of a phantom acquired for CT reconstruction. These images were used with the simultaneous algebraic reconstruction technique to reconstruct digital tomosynthesis tomograms with a slice thickness of 5 mm. For each dataset, the effective slice thickness was determined and compared to the known slice thickness of tomograms reconstructed using all the images (basically a CT reconstruction). Results: As expected, the effective slice thickness decreased with decreasing tomosynthesis angle, being almost three times the value of a CT‐reconstructed slice when the tomosynthesis angle was 10 degrees. However, when the tomosynthesis angle was kept constant, the effective slice thickness did not vary much. Conclusion: Since the out‐of‐plane spatial resolution seems to depend only on the tomosynthesis angle, this opens up the option of using fewer projections for digital tomosynthesis. This approach would be beneficial since it would decrease the patient's imaging dose.
SU‐GG‐I‐132: Refinements to the Deformation Model of an Anthropomorphic Computer Generated Breast Phantom
Authors: Xia S , Liu F , Maidment A , Bakic P
Published: August 2010

Purpose: We have previously developed a method for generating synthetic mammograms and breast tomosynthesis images of an anthropomorphic computer generated breast phantom. Mammographic compression of the phantom was simulated based upon a finite element (FE) deformation model. Currently, the compressed phantom is affected by artifacts arising during deformation. In this paper we investigate two refinements to the deformation model. Method and Materials: The mammographic compression simulation involves three steps. First, the undeformed voxel phantom is transformed into a mesh of tetrahedral elements, with each element encompassing several hundred voxels. Decimation reduces the computational complexity of the finite element model. Second, an FE deformation model is applied resulting in a deformed mesh. Finally, the deformed phantom is voxelized by interpolation. Each voxel in the undeformed and deformed phantoms encode a single tissue type. To reduce deformation artifacts we supersampled the deformed phantom during interpolation; uniformly spaced 3×3×3 sub‐voxel sampling points were used for each deformed voxel. In addition, we introduced rules governing the assignment of the tissue type to each voxel in the deformed phantom. Each voxel is now assigned the tissue type most frequently referred to by the supersampling points. These refinements were evaluated by analyzing phantoms whose interior consisted of regularly spaced parallel planes. Results: Without supersampling, 33.6% of the undeformed phantom voxels were not used during interpolation; supersampling reduced the number to 0.2%. The refined rules governing the tissue assignment improved the smoothness of the boundaries between simulated tissues; particularly near the interface between the breast phantom and air, where previously voxels incorrectly assigned as air produced noticeable artifacts. Conclusion: The refinements of the phantom compression model improve the simulation of tissue structures. This is especially important for the simulation of small structures (e.g., microcalcifications).
SU‐GG‐I‐134: Performance Evaluation of a Cone Beam O‐Arm Imaging System
Authors: Zhang J , Lin J , Qin L , Ritenour E
Published: August 2010

Purpose: The O‐arm cone beam imaging system has gradually been accepted to support different orthopedic surgery applications such as spine surgical procedures, assessment of pedicle screw position, kyphoplasty procedures, etc. Its 3D mode provides enhanced imaging information and may lead to enhancement in the surgical procedure compared to radiographs or fluoroscopy alone. Dosimetric characterization of the O‐arm imaging system has been presented in our previous study. This study aims to evaluate performance of the O‐arm system. Method and Materials: Noise Power Spectrum (NPS), Modulation Transfer Function (MTF) and Detective Quantum Efficiency (DQE) were evaluated for a cone beam O‐arm system. Image quality measurements were performed with a CATPHAN 424 phantom using a 120 kVp beam filtered with 1 mm Al and 0.1 mm Cu and an exposure range of 5.03 mGy to 8.17 mGy. The CPT445 Module was used to measure MTF. Water phantom images were used to calculate NPS. Then the NPS was normalized by dividing the square of the mean signal. The Photon fluence at each exposure (q) was estimated using the SpekCalc and compared to those by Monte Carlo simulation. The DQE was calculated using the measurements of the MTF, NNPS and q. Results: The MTF indicates that the reconstruction filter of the O‐arm is over‐enhancing, meaning that it yields values greater than unity. The system has a 10% MTF at 0.45mm. The NPS shows the low frequency structured noise present. The DQE reaches a maximum value of approximately 60% at low frequency. Conclusion: The physical characteristics, including the characteristic response, MTF, NPS and DQE of the O‐arm with a Varian flat panel detector (PaxScan 4030CB) were evaluated. The O‐arm system operated at 3D mode functions as a CT system, with comparable high spatial resolution but low spatial contrast and relatively large image noise.
SU‐GG‐I‐135: Assessment of the Correlation between Daily Set‐Up Patient Positioning Correction Values of an On‐Board KV Imaging System and the Radiation Technologist Rank
Authors: Meir Y , Schifter D , Shtraus N
Published: August 2010

Purpose: To examine the daily patient set‐up positioning error vs. the radiation technologist rank, by deriving it from the XVI image fusion correction values. Method and Materials: A set of 5 prostate, 5 head & neck and 4 lung cancer patients had been taken for this comparison. All of the patients were treated in IMRT Step & Shoot technique. For each patient the following data was extracted: (1) 10 XVI scans randomly picked and three parameters were taken, the table shift in 3 axis: longtitudal, lateral, vertical. (2) The names of the radiation technologists correlating to the date of the XVI scan. Three intervals of fusion correction were defined: 2–3 [mm], 3–5 [mm], greater then 5 [mm]. Radiation technologists were ranked by compiling a set of categories such as: chronological time at work, overall assessment of the institute senior staff in a scale of 1–5 (1‐High Rank; 5‐Low Rank). Results: There is a definitive match between the value of the correction and the number of corrections in total per patient and the radiation technologist rank. Radiation technologists that were ranked 4 or 5 constitute most of the fusion corrections above 3 and 5 [mm] in patients positioning. A combination pair of radiation technologists that were ranked as 4 or 5 increased the correction in two forms: (1) more then one axis was corrected (2) the value of the correction was high. A combination pair of a median rank and high rank radiation technologist yielded better results then a pair of a median rank and low rank radiation technologist. Conclusion: This work clearly indicates the on‐going strive for the education of the technical staff, as a vital link in patient positioning which leads to administrating the correct dose to a patient, in an accurate treatment modality such as IMRT.
SU‐GG‐I‐141: Quantification of FA and ADC Changes with Age in the Brainstem of Healthy Children Using Diffusion Tensor Imaging
Authors: Zhang Y , Jones M , Scoggins M , Ogg R , Hua C
Published: August 2010

Purpose: To provide a benchmark for comparison with diseased and injured pediatric brainstem, we quantified age‐dependent changes in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in 20 healthy children with diffusion tensor imaging (DTI). Method and Materials: Diffusion raw images were acquired in 20 healthy volunteer children aged 6–25 years using a 3‐T MR scanner (Trio, Siemens, Erlangen, Germany). Quantitative FA and ADC maps were computed offline using Siemens Neuro3D Syngo DTI task card. FA and ADC maps from multiple time points were co‐registered through T1‐weighted 3D structural scans. Regions‐of‐interest (ROIs) were manually delineated using an in‐house image analysis package. FA and ADC averages across the previously defined ROIs were fitted over the natural logarithm of age. FA and ADC were also averaged on each slice to examine the inter‐slice variation. Results: The fitted curves show a rising trend of FA but a decreasing trend of ADC with age as indicated by their slopes (pons: FA 0.07, ADC −0.08; corticospinal tract: FA 0.07, ADC −0.03; medial lemniscus: FA 0.06, ADC −0.06). The average FA of brainstem ROI over each slice was low in the medulla oblongata and increased towards pons and midbrain, as opposed to the high ADC in the medulla oblongata, deceasing in the pons and the midbrain. Conclusion: The increasing trend of FA and decreasing trend of ADC with age in pediatric brainstem was consistent with previous reports. The similar slopes with FA as compared to different slopes with ADC might indicate incongruence in characterizing the underlying structural changes. The slice‐by‐slice analysis demonstrates a large variation in FA and ADC in the craniocaudal direction within the brainstem. Our results from healthy subjects can provide an important benchmark for later comparison with pediatric patients receiving cancer treatment involving brainstem. Acknowledgement: NIH grant HD049888 and ALSAC.
SU‐GG‐I‐149: Positive MRI Contrast Agent Based on Gd2O3 Nanoparticles for Cell Tracking
Authors: Riyahi‐Alam N , Behrouzkia Z , Seifalian A , Haghgoo S
Published: August 2010

Purpose: In this study nanoparticles of gadolinium oxide have been investigated for intracellular uptake and capacity to generate a positive contrast. For this purpose two novel composed of a) silicon‐based nanocomposite polymer(NCP), b) Diethylene glycol (DEG) based coating material, both loaded with gadolinium(III) oxide (Gd2O3) nanoparticles were used. Method and Materials: This study would be involved with nanoparticles composed gadolinium (III) oxide, a) emulsified with a silicon‐based nanocomposite polymer and b) capped with Diethylene glycol (DEG) by polyol method starting from of Gd2O3 large particles, leading to Gd2O3 nano size capping with polymers. Prpoerties evaluation of nanoparticles were assessed previously by this group. Presently, cytotoxicity of gadolinium oxide nanoparticles in U‐87 MG cancer cells was evaluated. Furthermore relaxivity of particles in U‐87 cells were compared to particles in cell culture medium. Results: The results showed that Gd2O3‐labeled cells have shorter T1 and T2 relaxation times compared with untreated cells. The slope of r1 relaxivity (1/T1) vs. concentration curve in cell samples and ccm of Gd2O3 (NCP)were 10.87 and 10.60 s−1mM−1 and for Gd2O3 (deg) were 13.99, 13.66 s−1mM−1 respectively. The slope of r2 relaxivity (1/T2) vs. concentration curve in cell samples and ccm of Gd2O3 (NCP) were 17.26 and 15.13s−1mM−1 and for Gd2O3 (deg) were 16.35, 14.62 s−1mM−1 respectively. Conclision: A prominent difference in signal intensity was observed, indicating that Gd2O3 nanoparticles can be used as a positive contrast agent for cell labeling. No appreciable toxicity was observed with a Gd2O3 nanoparticles. Conclusion: Gadolinium‐Nanocomposite Polymer Emulsion is well characterised and potentialy useful positive contrast agent for magnetic resonance molecular imaging.
SU‐GG‐I‐154: Evaluation of Quantitative Potential of Breast Tomosynthesis Using a Voxelized Anthropomorphic Breast Phantom
Authors: Mehtaji D , Shafer C , Chen B , Lo J
Published: August 2010

Purpose: To assess the quantitative potential of breast tomosynthesis by estimating the percent density of voxelized anthropomorphic breast phantoms. Method and Materials: A Siemens breast tomosynthesis system was modeled using Monte Carlo methods and a voxelized anthropomorphic breast phantom. The images generated by the simulation were reconstructed using Siemens filtered back‐projection software. The non‐uniform background due to scatter, heel effect, and limited angular sampling was estimated by simulating and subtracting images of a uniform 100% fatty breast phantom. To estimate the density of each slice, the total number of fatty and glandular voxels was calculated both before and after applying a thresholding algorithm to classify voxels as fat vs. glandular. Finally, the estimated density of the reconstructed slice was compared to the known percent density of the corresponding slice from the voxelized phantom. This percent density estimation comparison was done for a 30%‐ and a 60%‐ dense 5cm breast phantom. Results: Without thresholding, overall density estimation errors for the central eleven slices were 0.64% and 2.1% for the 30% and 60% dense phantoms, respectively. After thresholding to classify voxels as fat vs. glandular, errors for central eleven were 3.5% and 6.2%, respectively. Voxel to voxel matching of the phantom vs. reconstructed slice demonstrated 80.3% and 73.08% respectively of voxels were correctly classified. Conclusion: The errors in slice density estimation were within 10% for both the phantoms thus implying that quantification of breast density using tomosynthesis is possible. However, limitations of the acquisition and reconstruction process continue to pose challenges in density estimation leading to potential voxel to voxel errors that warrant further investigation. Conflict of Interest:Joseph Lo: research grant and consultant, Siemens Healthcare.
SU‐GG‐I‐169: Effective Photodynamic Dose Delivered by Head and Neck Visualization Light Sources
Authors: Finlay J , Quon H , Sinha A , Malloy K
Published: August 2010

Purpose: In photodynamic therapy (PDT), it is possible that light sources used for visualization can cause unintended dose delivery. We sought to determine the effective PDT dose delivered by these light sources to provide guidelines for their safe use. Method and Materials: We have measured the spectrum and power of a range of light sources typically used in the evaluation of head and neck cancer. The power was measured using a calibrated thermopile detector when possible, and separately using a semiconductor photodiode attached to a 6‐inch integrating sphere. The integrating sphere was connected to a fiber‐optic spectrograph, which recorded the spectrum of each lamp. The relative sensitivities of the photodiode detector and spectrograph were evaluated relative to the sensitivity at 630 nm. The spectral power of each source was multiplied by the published excitation spectrum of the photosensitizer protoporphyrin IX (PpIX) to obtain an effective power, defined as the power at 630 nm required to produce the level of PpIX excitation as the source. This effective power was used to determine the maximum exposure time for each source. We have evaluated the effect of colored plastic optical filters placed on these sources. Results: We have characterized the output of several light sources. The equivalent power emitted by these sources varies from tens to hundreds of milliwatts. The effective power can be reduced by up to a factor of three by appropriate filtration.. The effectiveness of this filtration is dependent on the light source spectrum and the sensitizer being used. Exposure time recommendations are summarized for each light source. Conclusion: A range of light sources may be suitable for use in conjunction with PDT. These light sources can be used safely and effectively through a combination of limited exposure time and appropriate filtration.
SU‐GG‐I‐184: New Graphical User Interface for the Solid State X‐Ray Image Intensifier (SSXII)
Authors: Wang Weiyuan , Kuhls‐Gilcrist A , Ionita C , Huang Y , Qu B , Bednarek D , Rudin S
Published: August 2010

Purpose: A new Graphical User Interface (GUI) was developed and implemented using Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) for a high‐resolution, high‐sensitivity SSXII, a new x‐ray detector for radiographic and fluoroscopic imaging. Method and Materials: The new SSXII consists of an array of Electron Multiplying Charge Coupled Devices (EMCCDs). EMCCDs are enhanced CCD image sensors with a unique feature that includes variable on‐chip signal amplification of up to 2000 times. These low‐noise light sensors view an x‐ray phosphor through a fiberoptic taper used to enlarge the field of view (FOV). An array of such modules has been built to further extend the FOV. The initial 1×2 array includes two identical EMCCD cameras connected to a National Instruments (NI) PCIe‐1430 dual‐channel Camera Link PC board. A new GUI was developed and implemented using LabVIEW for camera control, image acquisition, and to provide a variety of clinically‐relevant functions. Results: The GUI provides a user‐friendly interface that includes patient registration functionality and acquisition control to save 2k×1k images at a rate of 17 Hz (or faster with pixel binning). The parameter sets of each camera, including control of exposure time, trigger mode, and EMCCD gain, can be modified during imaging runs. An additional window allows the user to control all of the other camera parameters, which can be subsequently saved to a text file for reference. Initial 1×2 EMCCD camera array will be expanded to provide even larger FOVs. Conclusion: The control and acquisition capabilities provided by this GUI, along with the variable electron‐multiplication gain, high‐resolution, high‐sensitivity, and real‐time imaging capabilities of the new expanded‐FOV SSXII should provide angiographers and interventionalists with an improved ability to visualize details of small vessels and endovascular devices, making diagnoses and image‐guided interventions more accurate. (Supported by: NIH Grants R01‐EB008425, R01‐EB002873)
SU‐GG‐J‐24: Retrospective Clinical Data Analysis of Fiducial‐Free Lung Tracking
Authors: Jordan P , West J , Sharda A , Maurer C
Published: August 2010

Purpose: To present the algorithmic approach used in the Xsight® Lung Tracking System (XLT; Accuray Incorporated, Sunnyvale, CA) of the CyberKnife® Robotic Radiosurgery System (Accuray Incorporated) and to quantify the expected proportion of lung radiosurgery candidates suitable for fiducial‐free motion‐compensated treatment using orthogonal kV imaging. Method and Materials: The XLT system was recently enhanced with the goal of increasing the proportion of lung lesions that can be tracked in orthogonal kV x‐ray image pairs without fiducials. These enhancements include digitally reconstructed radiographs generated from local tumor neighborhoods, an automatic preferred projection epipolar constraint, tumor template matching allowing for in‐plane rotations, and automatic x‐ray image enhancement. An extensive multi‐institutional (M=5) cohort of patients (N=103) was retrospectively analyzed to quantify fiducial‐free target localization performance for lung tumors spanning a broad range of anatomical locations and sizes (largest dimension ranged from 10 to 100 mm). This analysis evaluated 7,565 x‐ray image pairs to quantify the localization performance of the XLT system in comparison to fiducial localization as a gold standard. Clinical cases were categorized as “fiducial‐free candidates” when XLT localization satisfied preset accuracy, quality assurance and detection confidence metrics in over 75% of the tested image pairs. Results: A total of 57 out of 103 cases (55.3%) were found to be suitable candidates for fiducial‐free treatment. The site‐specific fiducial‐free candidate ratios ranged from 40% to 78% of all lung radiosurgery candidates, reflecting variability in patient population, tumor locations and sizes (algorithm works best for tumors larger than 15 mm in diameter), and x‐ray imaging technique. Conclusion: This study demonstrates that fiducial‐free localization and motion compensation can be achieved in over half of lung radiosurgery candidates using the recently enhanced XLT system, while maintaining tracking accuracy comparable to that obtained using implanted fiducial markers.

Conflict of Interest: The authors are employed by Accuray Incorporated.
SU‐GG‐J‐47: Verification of a Deformable Image Registration Algorithm for Head and Neck Cancer Therapy
Authors: Dogan N , Sleeman W , Fatyga M , Lehman W , Christensen G , Wu J , Weiss E , Zhang B , Williamson J
Published: August 2010

Introduction: H&N cancer patients may require frequent CT imaging for re‐planning due to significant anatomical changes to improve dosimetric accuracy. A challenging task is manual delineation of target(s) and normal structures on each image sets acquired on different days. The aim of this study was to verify a Small Deformation Inverse Consistent Linear Elastic (SICLE) deformable image registration for its ability to deformably‐map contours on H&N image sets by comparing them to physician‐drawn contours. Methods and Materials: Six patients with H&N cancer who had frequent CT imaging were selected. GTVs, parotids, cord and brainstem were physican‐drawn on both source and target image sets. Physician‐drawn contours on source image set were deformed by the DVFs to produce deformably‐mapped contours and dose on target images. Differences between the physician‐drawn and deformably‐mapped contours were compared using: “Differences in volumes(Vdiff)”, “differences in center of mass(COMdiff)”, “volume overlap index(VOI)”, “3D‐perpendicular‐distance‐maps”. To evaluate the clinical usefulness, plans were generated based on the physician‐drawn and deformably‐mapped contours. Furthermore, the dose from source image was deformed to target images using the DVFs. Plans were compared for their coverage of physician‐drawn contours. Results: While GTV and NodalGTV VOIs ranged from 0.57 to 0.72 and 0.57 to 0.79 respectively, for parotids, brainstem and cord, it varied from 0.42 to 0.82. Up to 1.7cm and 2.9cm discrepancies were observed in esophagus and cord COM in z direction. Visual comparison of physician‐drawn and deformably‐mapped GTVcontours showed a reasonably well agreement. Dosimetric impact of contour differences was not very significant with <5% differences in PTV D95. Conclusion: SICLE algorithm can produce high quality contours on subsequent H&N image sets. However, manual modification of deformably‐mapped contours may be necessary. Deformably‐mapped contours can be used as a QA tool for inspecting manually‐drawn contours, in addition to reducing or even eliminating the manual contouring workload.
SU‐GG‐J‐50: The Role of 4DCT Sorting in Treatment Planning for Image‐Guided Radiation Therapy
Authors: Glide‐Hurst C , Zhong H , Kim J , Chetty I
Published: August 2010

Purpose: Deformable image registration (DIR) is an integral component of adaptive radiotherapy, however reconstruction artifacts induced from improper 4DCT sorting can be detrimental to DIR performance. This study evaluated, both in phantom and patient, the impact of a novel hybrid amplitude‐based 4DCT sorting algorithm on DIR quality, and the results were compared with conventional phase‐based sorting. Method and Materials: A series of phantom experiments were performed using a respiratory motion platform programmed with phantom ((1−cos2), 5 second cycle) and patient (abdomen displacement from RPM data) breathing curves with lung‐tumor excursion in S‐I direction. 4DCT images were acquired, and corresponding datasets were sorted (10 phases) using both phase and hybrid amplitude‐based sorting algorithms. DIR was performed between phases using a Diffeomorphic Demon's algorithm and the resultant displacement vector fields (DVFs) were analyzed. The unbalanced energy (UE), a metric proven to detect registration errors, was assessed between sorting techniques, with high UE values indicating regions of non‐physical deformation. Our approach was further validated through retrospective evaluation of a lung cancer patient's 4DCT. Results: A marked improvement in 4DCT sorting with the hybrid amplitude gating approach and the resulting UE was observed for all phantom experiments. An average decrease in UE of 34.0% (range: 19.7 – 43.2%) and 31.5% (range: 25.0 – 42.9%) for the mean and maximum, respectively, were observed. The retrospective patient study revealed significant improvement in DIR performance; the hybrid amplitude approach reduced the average UE magnitude ∼30%, particularly near the diaphragm‐lung interface. Conclusion: We have demonstrated the potential improvement in DIR performance offered by hybrid amplitude‐based 4DCT sorting. An improvement in DIR quality, both visually and as quantified by UE, was observed for both phantom and patient. By describing the applicability of this technique, improvements in 4D dose calculation may be realized, potentially streamlining adaptive radiotherapy into clinical practice.