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計算機超聲引導針放置模擬系統近年受到醫學界密切關注。在過去十年，為應付各種需要，大量模擬系統被研發。與傳統訓練方法比較，使用計算機模擬系統作訓練擁有多種優點。例如：可控訓練環境，能重複使用的數據庫，以及客觀評核。至今，研究的主要方向依然是物理建構的模擬。雖然，更真實及更仔細的模擬系統能引發新的教學概念，系統開發的重點應該著眼於對訓練的影響。 / 本論文研究計算機超聲引導針放置模擬系統的最新發展。首先，我們會介紹計算機模擬系統的各個範疇及於醫學訓練的基本應用。使用計算機模擬系統作訓練用途的成效會被討論。然後，我們會討論幾種針對訓練成效的改進技術。這些技術包括一個動態訓練場景生成框架，綜合遊戲概念的方法，以及一種以臨床技術為本的穿刺提示規劃法則。它們對訓練的影響利用實驗作驗證。接著，我們介紹一個評核穿刺軌跡可視化技術的框架。我們的研究發現，穿刺軌跡的可視化技術對用家放置針的準確度有顯著的影響。這意味著模擬系統中穿刺軌跡的可視化技術需要經過非常小心的設計。最後，我們介紹一個超聲材質的描述器。這個描述器針對超聲材質的比較而設計。超聲材質的比較不止是在超聲模擬系統中重要的一環，更能被應用在各種醫學圖像的研究中。 / Computer-based ultrasound guided needle placement simulators have gained extensive attention of the medical society. In the last decade, a lot of simulators have been proposed to suit different purposes. Advantages of using computer-based simulators over traditional training include controlled training environment, reusable case database and objective evaluation. Yet, the most studied aspect of computer-based simulators remains the simulation of physical situations. Though a more realistic and detailed simulation enables new training concepts, the origin of any development shall be its effect on training. / This thesis studies the latest development of computer-based ultrasound guided needle placement simulators. We first introduce basic aspects of computer-based simulators and their applications on medical training. The effects on computer-based training over traditional methods are discussed. Secondly, we present various techniques that aim for effective training. These techniques include a framework for dynamic case generation, an integration of serious game concepts, and a recommendation scheme based on clinical practices. Their impacts on training are evaluated through various experiments. Thirdly, we present an evaluation framework for the visualization of needle access pathway. Our study shows that the adoption of visualization techniques significantly affects users' performance of needle alignment. This implies that a careful design of the visual effect inside a simulator is necessary. Lastly, we present a descriptor for ultrasound textures. This descriptor is designed for ultrasound textural comparison which is an important step for not only ultrasound simulators but also other medical imaging applications. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Chan, Wing Yin. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 100-114). / Abstracts also in Chinese. / Chan, Wing Yin.

<p>The aims of this work were to image and analyze the needle behavior at automated core biopsy, to investigate the clinical utility of an alternative core biopsy technique using a semiautomated gun in breast and axillary lesions, and also to compare core biopsy with surgical specimens in malignant breast lesions regarding histologic features and hormone receptor expression.</p><p>In two experimental studies, using butter and silicon phantoms, respectively, the needle pass was imaged and its dynamic behavior studied. It was shown that the needle took a curved course in phantoms. It deviated to the same side as where the tip lay, and the degree of the curvature increased with increasing hardness of the phantoms. Our experimental methods can be applied for imaging of needle behavior and thereby improvement of needle configuration.</p><p>In two clinical studies, a semiautomated gun was used for large needle core biopsy of breast and axillary lesions in two series of 145 and 21 patients, respectively. The sensitivity of the method for diagnosis of malignancy was 87% (108/124), and in 37% (31/83) of cases the full length of the needle notch was filled with specimen. No injury to the neurovascular structures of the axillary area was observed. It was concluded that the semiautomated gun can be used as an alternative to the automated gun when the size and location of the lesion render use of the automatic device uncertain or dangerous, e.g., in small breast lesions or lesions located in the axilla.</p><p>In a series of 129 cases of breast cancer, comparison of core biopsy and surgical specimens showed that core biopsy provided enough information on the histologic type and grade of the lesions. Also, there was moderate to high concordance between the two methods for assessment of progesterone receptors and estrogen receptors (Spearman`s kappa 0.67 and 0.89, respectively).</p>

The aims of this work were to image and analyze the needle behavior at automated core biopsy, to investigate the clinical utility of an alternative core biopsy technique using a semiautomated gun in breast and axillary lesions, and also to compare core biopsy with surgical specimens in malignant breast lesions regarding histologic features and hormone receptor expression. In two experimental studies, using butter and silicon phantoms, respectively, the needle pass was imaged and its dynamic behavior studied. It was shown that the needle took a curved course in phantoms. It deviated to the same side as where the tip lay, and the degree of the curvature increased with increasing hardness of the phantoms. Our experimental methods can be applied for imaging of needle behavior and thereby improvement of needle configuration. In two clinical studies, a semiautomated gun was used for large needle core biopsy of breast and axillary lesions in two series of 145 and 21 patients, respectively. The sensitivity of the method for diagnosis of malignancy was 87% (108/124), and in 37% (31/83) of cases the full length of the needle notch was filled with specimen. No injury to the neurovascular structures of the axillary area was observed. It was concluded that the semiautomated gun can be used as an alternative to the automated gun when the size and location of the lesion render use of the automatic device uncertain or dangerous, e.g., in small breast lesions or lesions located in the axilla. In a series of 129 cases of breast cancer, comparison of core biopsy and surgical specimens showed that core biopsy provided enough information on the histologic type and grade of the lesions. Also, there was moderate to high concordance between the two methods for assessment of progesterone receptors and estrogen receptors (Spearman`s kappa 0.67 and 0.89, respectively).

Master of Science / Department of Clinical Sciences / Warren L. Beard / Objectives: To quantify recovery of colored microspheres from cadaver tarsocrural joints via arthroscopic or needle lavage, and to compare recovery for 1-5L of lavage fluid. Study design: Randomized experimental trial. Methods: 8 adult Quarter Horse cadavers had 1.5 million 15μm, colored microspheres injected into each tarsocrural joint. Each joint was randomly assigned to receive lavage with an arthroscope and egress cannula (group A) or three (1 ingress, 2 egress) 14 gauge needles (group N) with 5L 0.9% NaCl. The egress fluid from each liter of lavage was collected separately, and the number of microspheres present in each recovered liter was determined via spectrophotometry. Results: A significant interaction (p<0.01) was present between treatment group and liter. The number of microspheres recovered in the first liter of lavage fluid was significantly higher in the needle group than in the arthroscope group (p<0.01). For both groups the number of microspheres recovered in the first liter of lavage fluid represented a majority of the total microspheres collected, and was significantly different from the subsequent liters collected (p<0.01). The number of microspheres recovered did not differ between liters 2, 3, 4, and 5, within or between treatment groups. Conclusions: In this model, tarsocrural lavage with three 14-gauge needles was more effective at removing colored microspheres from the joint than arthroscopic lavage, suggesting the number or placement of portals present may be more important than portal size and flow rate. No difference in microsphere recovery was seen with lavage volumes greater than 1L.

Puncture resistance is among the major mechanical properties often required for protective clothing, especially in the medical sector. However the intrinsic material parameters controlling puncture resistance of protective materials are still unknown. Therefore, the purpose of this work is to study the mechanism and mechanical behaviors of puncture resistance of protective clothing materials to various probe types. A better understanding of puncture mechanics will be helpful to develop suitable methods to evaluate the puncture resistance and to predict the failure of protective clothing materials. The thesis includes 4 articles which expose two major phases in this study. Article I and II studied the mechanics and mechanisms of puncture by conical and cylindrical probes used in the standard test methods (ASTM F1342 and ISO 13996). The results show that the punctures of rubber membranes by conical and cylindrical probes are controlled by a maximum local deformation (or puncture failure strain) that is independent of the probe geometry. The puncture strengths of elastomer membranes are much lower than their tensile and biaxial strengths. In addition, a simpler cylindrical probe can be used in the place of the costly conical probe required by the ASTM standard and still provides a quantitative characterization of puncture. Actually, since 2005, an alternative method B had been added to F1342 ASTM with 0.5 mm-diameter rounded-tip cylindrical probe. Furthermore, the puncture probes used in the ASTM F1342 are very different to the actual pointed objects (medical needle, pointed tip of knife... ) and cannot accurately characterize the puncture resistance to real objects. Therefore, in the second step, the mechanics and mechanisms of puncture by medical needles were studied. Article III shows that the puncture by sharp-pointed objects like medical needles is very different from the puncture by conical probes used in the ASTM standard test. For medical needles, the puncture resistance involves cutting and fracture energy of material. Using the fracture mechanics, based on the change in strain energy with the change in fracture surface, the fracture energy in puncture was estimated. This calculation assumes that there is no friction between the needle tip and fracture surface. However, even with the application of a lubricant on the needle surface, the effect of friction on the puncture process cannot be totally eliminated, preventing the determination of the material fracture energy. Therefore, Article IV has described a method, similar to that of Lake and Yeoh for cutting to access the precise value of fracture energy in puncture of rubbers by sharp-pointed objects. The method allows substantially eliminating the effects of friction on the evaluation of the fracture energy involved in the puncture process.

Thesis (PhD (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / AFRIKAANSE OPSOMMING: Min aandag is al gegee aan biogeomorfologiese interaksies in glasiale en periglasiale omgewings. Nietemin is hierdie interaksies, wat op die skeidingsvlak tussen ekologie en geomorfologie fokus, baie belangrik in hierdie omgewings, waar organismes in noue verband met die abiotiese omgewing saamleef. In hierdie tesis bestudeer ek die interaksies tussen die vaskulêre plantspesies met die hoogste voorkoms op sub-Antarktiese Marion Eiland, Azorella selago Hook. (Apiaceae), en die omringende geomorfologiese landskapsvorme, -prosesse en meettegnieke. Verder verskaf die tesis voorstelle om toekomstige geïntegreerde biogeomorfologiese navorsing te vergemaklik. Om die gevolge van A. selago-plante vir sedimentbeweging en -verspreiding te verstaan, het ek die verspreiding van sedimentgroottes om hierdie plante gemeet deur middel van 'n kombinasie van fotografiese analise-metodes. Deur as sedimentbewegingsobstruksies te dien, het plante 'n waarneembare effek op die omringende sedimentverdeling. Dit is veral belangrik om hierdie interaksies tussen A. selago en sy omgewing te verstaan in die lig van onlangse klimaatsverandering op die eiland, omdat sedimentgrootte belangrike grondeienskappe soos waterretensiekapasiteit en vriesgevoeligheid beïnvloed. Om die effek wat A. selago plante op die omringende mikroklimaat het beter te verstaan, is die kleinskaalse variabiliteit in grondtemperature om A. selago plante bestudeer. Grootskaalse grondligting as gevolg van fors is gemeet, ten spyte van relatief ligte forseienskappe. Dit dui daarop dat naaldys ook by temperature bo -2°C kan vorm. Wintergrondtemperature aan die oostekant van plante was effens laer en minder veranderlik as aan die westekant van plante, waarskynlik as gevolg van laer windsnelhede en/of sneeu wat ophoop aan die oostelike, lykant van plante. Die resultate benadruk dat A. selago plante 'n belangrike rol speel in die verandering van mikroklimate en dat dit belangrik is om die gevolge van sulke veranderings, soos die skep van mikrohabitatte vir grondorganismes, te verstaan. Daar word vermoed dat positiewe plantinteraksies negatiewe interaksies oorheers in omgewings met hoe abiotiese druk. Gevolglik wys ek dat daar 'n positiewe verband bestaan tussen A. selago plante en saailinge van beide A. selago self, asook van die meerjarige gras Agrostis magellanica Lam. (Poaceae). Ek stel voor dat beide plante en klippe sade, wat deur wind, reenval en/of afdraande sedimenttransportering as gevolg van vriesprosesse vervoer word, opvang. Verder dui verhoogde A. selago saailinggetalle om plante, maar nie om klippe nie, daarop dat plante een of ander biologiese voordeel aan A. selago saailinge bied. Dit is bekend dat die verspreidingspatrone van plantspesies as gevolg van abiotiese stresgradiente varieër. Met hierdie bevinding in gedagte, is moontlike faktore verantwoordelik vir A. selago saailinggetalle en -verspreidingspatrone, soos hoogte bo seespieël en substraatbedekking, bestudeer. Alhoewel dit wil voorkom asof daar 'n verband tussen saailinggetalle en hoogte bo seespieël is, is saailinggetalle en verpreidings meestal afhanklik van ongemeette perseel-spesifieke eienskappe. Plante kan die omringende geomorfologie beïnvloed, maar ook geomorfologiese meettegnieke. Om die potensiaal van kosmogeniese dateringsmetodes as geomorfologiese hulpmiddels in fellfield habitatte te verken, is die akkumulasietempo van die kosmogeniese isotoop ¹ºBe onder en langs 'n A. selago plant bepaal. Die resultate dui daarop dat ¹ºBe nie ten volle in die grondprofiel behoue bly nie en verskeie potensiële redes word bespreek. Verder dui die resultate daarop dat ¹ºBe konsentrasies in fellfield habitatte versigtig geïnterpreteer moet word, aangesien A. selago plante effektief ¹ºBe opvang in hulle grondryke kern. Om vordering in biogeomorfologie te vergemaklik, is dit belangrik om bewus te wees van die verskillende metodes wat geomorfoloë en ekoloë volg. Ekologiese benaderings is dikwels op strenger statistiese tegnieke gebaseer, terwyl geomorfoloë eerder fokus op 'n meer beskrywende benadering en teoretiese beredenering. Ek verduidelik hoekom die twee velde sulke uiteenlopende benaderings volg, benadruk moontlike struikelblokke en verskaf voorstelle om samewerking te vergemaklik. / ENGLISH ABSTRACT: There are few scientific publications that relate to biogeomorphological interactions in glacial and periglacial environments. Interactions that focus on the interface between ecology and geomorphology are very important in these environments, as a tight coupling often exists between organisms and their abiotic surroundings. In this thesis the interactions between the dominant vascular cushion plant species on sub-Antarctic Marion Island, Azorella selago Hook. (Apiaceae), and the surrounding geomorphological landforms, processes and measuring techniques were studied. In addition, the thesis provides suggestions to facilitate future integrated biogeomorphological research. To understand the consequences of A. selago cushions for substrate movement and sorting, the grain size distribution of sediment surrounding these cushions was quantified using a combination of image analysis approaches. Through obstructing frost-related sediment transport, A. selago cushions are shown to affect the grain size sorting of the surrounding sediment. Particle size affects soil properties such as water-holding capacity and frost susceptibility. It is therefore important to understand the interactions between A. selago cushions and sediment distributions, especially in the light of recent warming and drying on the island. Fine scale variability in soil temperature parameters was studied around cushions to improve understanding on how A. selago affects the surrounding soil microclimate. Despite the mild frost climate, extensive frost heave occurred in the study area, indicating that needle ice forms above the previously suggested required temperature of -2°C. Lower and less variable winter temperatures were found on eastern than on western cushion sides, probably as a result of lower wind speeds or leeside snow accumulation on eastern cushion sides. These research findings highlight the importance of A. selago cushions in modifying site microclimates. Such modifications could have important potential consequences, such as providing microhabitats for soil microorganisms and seedlings. Positive plant interactions have been suggested to dominate over negative interactions in environments with high abiotic stress. Positive associations were found between A. selago and both its own seedlings and those of the perennial grass, Agrostis magellanica Lam. (Poaceae) on Marion Island. It is suggested that both cushions and rocks trap seeds dispersed by wind, runoff and/or downslope sediment transport through frost creep. In addition, increased A. selago seedling numbers around cushions, but not around rocks, suggest that cushions provide a biological nurse effect to seedlings of their own kind. Plant species' distributions have been known to vary in response to abiotic stress gradients. In light of this, determinants of A. selago seedling distributions and abundance, such as altitude and substrate cover, were explored. Although there appears to be some altitudinal trend, seedling distributions and abundance patterns were largely attributed to unaccounted variation between sites. Plants can affect the surrounding geomorphology, but also geomorphological measuring techniques. To explore the potential of cosmogenic dating techniques as geomorphological tools in fellfield habitats, accumulation rates of the cosmogenic isotope ­¹ºBe were assessed underneath and adjacent to an A. selago cushion. The results show that ¹ºBe is not fully retained in the soil profile and various reasons are discussed. Furthermore, the results suggest that ¹ºBe concentrations should be interpreted cautiously in fellfield habitats, as A. selago cushions effectively intercept the isotope in their soil-rich core. To facilitate the integration of geomorphological and ecological principles, as was attempted in this thesis, it is important to understand the philosophies behind the different research approaches that ecologists and geomorphologists employ. Ecologists often employ a more statistics-based approach, whereas geomorphologists focus on a more descriptive approach and reasoning based on established theories. I attempt to explain why the two fields follow such different approaches, highlight some potential challenges and provide suggestions to facilitate progress in the interdisciplinary field of biogeomorphology.

In der vorliegenden retrospektiven Studie werden die Daten von 103 Patienten mit Resektionen am Ösophagus am Klinikum Sankt Georg, Leipzig, welche vom 01.01.2000 bis zum 31.12.2011 durchgeführt wurden, analysiert. Es wird die Bedeutung der Feinnadelkatheterjejunostomie (FKJ) als Möglichkeit der frühen postoperativen enteralen Ernährung für ein visceralchirurgisches Patientengut dargelegt, bei dem nach den Leitlinien der Deutschen Gesellschaft für Ernährungsmedizin (DGEM) ein hohes ernährungsmedizinischem Risiko besteht. Bei den 91 angelegten FKJ im Studienkollektiv beträgt die Rate von Dislokationen oder Okklusionen der FKJ-Sonden insgesamt 5,5%, wobei sich im Vergleich mit 22 anderen Publikationen mit insgesamt 5220 Patienten Raten von 0,3% bis 7,7%, bei einem Median von 1,3, zeigten. Im vorliegenden Studienkollektiv waren keine operativen Revisionen aufgrund FKJ-assoziierter Komplikationen notwendig und es kam im Zusammenhang mit den FKJ zu keiner Komplikation mit letalem Ausgang. Die FKJ als Möglichkeit zur postoperativen enteralen Ernährung bei Patienten nach komplexen visceralchirurgischen Eingriffen am Ösophagus kann empfohlen werden. Des Weiteren wird der Frage nachgegangen, ob ein chirurgisches Zentrum, welches nach dem Katalog für Mindestmengen des Gemeinsamen Bundesausschusses (G-BA) Fallzahlen für komplexe chirurgische Eingriffe am Ösophagus im Bereich dieser Mindestmengen erfüllt, mit großen Zentren hinsichtlich der intraoperativen und postoperativen Komplikations-, Morbiditäts- und Letalitätsraten vergleichbar ist. Im Vergleich mit 20 Publikationen über die postoperativen Komplikationen nach Ösophagektomien mit Patientenzahlen von 32 bis 17395 zeigten sich die Daten der eigenen Studie ohne signifikante Abweichungen hinsichtlich pulmonaler, kardialer oder septischer Komplikationen. Intraoperativ kam es zu keinem Todesfall. Die Qualität der Behandlungsergebnisse eines visceralchirurgischen Zentrums ist abhängig von der langjährigen Erfahrung und den Fallzahlen der Operateure, sowie von der erfolgreichen interdisziplinären Zusammenarbeit im perioperativen Management der Patienten.

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