39 research outputs found
Algoritmos generales para simuladores de cirugÃa laparoscópica
Recent advances in fields such as modeling of deformable objects, haptic technologies, immersive technologies,
computation capacity and virtual environments have created the conditions to offer novel and suitable training tools and learning methods
in the medical area. One of these training tools is the virtual surgical simulator, which has no limitations of time or risk, unlike conventional
methods of training. Moreover, these simulators allow for the quantitative evaluation of the surgeon performance, giving the possibility to
create performance standards in order to define if the surgeon is well prepared to execute a determined surgical procedure on a real patient.
This paper describes the development of a virtual simulator for laparoscopic surgery. The simulator allows the multimodal
interaction between the surgeon and the surgical virtual environment using visual and haptic feedback devices. To make the
experience of the surgeon closer to the real surgical environment a specific user interface was developed. Additionally in this paper
we describe some implementations carried out to face typical challenges presented in surgical simulators related to the tradeoff
between real-time performance and high realism; for instance, the deformation of soft tissues are simulated using a GPU (Graphics
Processor Unit) -based implementation of the mass-spring model. In this case, we explain the algorithms developed taking into
account the particular case of a cholecystectomy procedure in laparoscopic surgery.Recientes avances en áreas tales como modelación computacional de objetos deformables, tecnologÃas hápticas, tecnologÃas
inmersivas, capacidad de procesamiento y ambiente virtuales han proporcionado las bases para el desarrollo de herramientas y métodos de
aprendizaje confiables en el entrenamiento médico. Una de estas herramientas de entrenamiento son los simuladores quirúrgicos virtuales,
los cuales no tienen limitaciones de tiempo o riesgos a diferencia de los métodos convencionales de entrenamiento. Además, dichos
simuladores permiten una evaluación cuantitativa del desempeño del cirujano, dando la posibilidad de crear estándares de desempeño con
el fin de definir en qué momento un cirujano está preparado para realizar un determinado procedimiento quirúrgico sobre un paciente.
Este artÃculo describe el desarrollo de un simulador virtual para cirugÃa laparoscópica. Este simulador permite la interacción
multimodal entre el cirujano y el ambiente virtual quirúrgico usando dispositivos de retroalimentación visual y háptica. Para hacer
la experiencia del cirujano más cercana a la de una ambiente quirúrgico real se desarrolló una interfaz cirujano-simulador especial.
Adicionalmente en este artÃculo se describen algunas implementaciones que solucionan los problemas tÃpicos cuando se desarrolla un
simulador quirúrgico, principalmente relacionados con lograr un desempeño en tiempo real mientras se sacrifica el nivel de realismo
de la simulación: por ejemplo, la deformación de los tejidos blandos simulados usando una implementación del modelo masa-resorte
en la unidad de procesamiento gráfico. En este caso se describen los algoritmos desarrollados tomando en cuenta la simulación de un
procedimiento laparoscópico llamado colecistectomÃa
Simulating soft tissues using a GPU approach of the mass-spring model
The recent advances in the fields such as modeling bio-mechanics of living tissues, haptic technologies, computational capacity, and graphics realism have created conditions necessary in order to develop effective surgical training using virtual environments. However, virtual simulators need to meet two requirements, they need to be real-time and highly realistic. The most expensive computational task in a surgical simulator is that of the physical model. The physical model is the component responsible to simulate the deformation of the anatomical structures and the most important factor in order to obtain realism. In this paper we present a novel approach to virtual surgery. The novelty comes in two forms: specifically a highly realistic mass-spring model, and a GPU based technique, and analysis, that provides a nearly 80x speedup over serial execution and 20x speedup over CPU based parallel execution. ©2010 IEEE
Parasite-modified behaviour in non-trophic transmission: trematode parasitism increases the attraction between snail intermediate hosts
Many parasites with complex life cycles cause host behavioural changes that increase the likelihood of transmission to the next host. Parasite modification is often found in trophic transmission, but its influence on non-trophic transmission is unclear. In trematodes, transmission from the first to second intermediate host is non-trophic, suggesting that free-swimming larvae (cercariae) emerging in closer proximity to the next host would have higher transmission success. We performed a series of behavioural experiments with echinostome trematodes and their snail hosts to determine if potential second hosts (ramshorn snail, genus Planorbella Haldeman, 1842) were more attracted to parasitized first hosts (marsh pondsnail, Lymnaea elodes Say, 1821). In a Y maze, a responding snail (Planorbella sp.) was placed in the base and its response to five treatments was assessed: no stimulus, turion duckweed (Lemna turionifera Landolt; a food item), non-parasitized L. elodes, parasitized L. elodes, and finally parasitized versus non-parasitized L. elodes. Snails showed some attraction to uninfected snails, but had a stronger response to infected first host snails. These results indicate that potential second host snails were more attracted to parasitized, heterospecific first host snails over non-parasitized heterospecific snails. This study demonstrates that echinostome trematodes alter snail behaviour by changing navigational choices in uninfected potential hosts through a chemical communication mechanism.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Immature and Mature Collagen Crosslinks Quantification Using High-Performance Liquid Chromatography and High-Resolution Mass Spectrometry in Orbitrap
Different methodologies for collagen quantification have been described in the past. Introduction of mass spectrometry combined with high-performance liquid chromatography (HPLC) is a high-resolution tool, which has generated novel applications in biomedical research. In this study, HPLC coupled to electrospray ionization (ESI) tandem mass spectrometry (HPLC-ESI-MS/MS) was used to characterize tissue samples from AVFs done in rats. These findings helped create a protocol for identifying and quantifying components of immature and mature collagen crosslink moieties. Two different internal standards were used: epinephrine and pyridoxine. Quantification curves were drawn by means of these standards. The goal of the experiment was to achieve accurate quantification with the minimum amount of sample. Time and cost of experiment were considerably minimized. Up to date, this method has not been tested for crosslinking quantification