Spectral imaging of thermal damage induced during microwave ablation in the liver

Induction of thermal damage to tissue through delivery of microwave energy is frequently applied in surgery to destroy diseased tissue such as cancer cells. Minimization of unwanted harm to healthy tissue is still achieved subjectively, and the surgeon has few tools at their disposal to monitor the spread of the induced damage. This work describes the use of optical methods to monitor the time course of changes to the tissue during delivery of microwave energy in the porcine liver. Multispectral imaging and diffuse reflectance spectroscopy are used to monitor temporal changes in optical properties in parallel with thermal imaging. The results demonstrate the ability to monitor the spatial extent of thermal damage on a whole organ, including possible secondary effects due to vascular damage. Future applications of this type of imaging may see the multispectral data used as a feedback mechanism to avoid collateral damage to critical healthy structures and to potentially verify sufficient application of energy to the diseased tissue.Comment: 4pg,6fig. Copyright 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other work

Herramienta software para la calibración extrínseca de cámaras infrarrojas y RGBD aplicada a inspección termográfica

Context:  Thermographic inspections are currently used to assess energy efficiency in electrical equipment and civil structures or to detect failures in cooling systems and electrical or electronic devices. However, thermal images lack texture details, which does not allow for a precise identification of the geometry of the scene or the objects in it. Method: In this work, the development of the software tool called DepTherm is described. This tool allows performing intrinsic and extrinsic calibration between infrared and RGBD cameras in order to fuse thermal, RGB, and RGBD images, as well as to record thermal and depth data. Additional features include user management, a visualization GUI for all three types of images, database storage, and report generation. Results: In addition to the integration tests performed to validate the functionality of DepTherm, two quantitative tests were conducted in order to evaluate its accuracy. A maximum re-projection error of 1,47±0,64 pixels was found, and the maximum mean error in registering an 11 cm side cube was 4,15 mm. Conclusions: The features of the DepTherm software tool are focused on facilitating thermographic inspections by capturing 3D scene models with thermal data.Contexto: Las inspecciones termográficas se utilizan en la actualidad para evaluar la eficiencia energética de equipos eléctricos y estructuras civiles o para detectar fallas en sistemas de enfriamiento y dispositivos eléctricos o electrónicos. Sin embargo, las imágenes térmicas carecen de detalles de textura, lo cual no permite identificar con precisión la geometría de la escena ni los objetos en ella. Método: En este trabajo se describe el desarrollo de la herramienta de software DepTherm, la cual permite realizar calibraciones intrínsecas y extrínsecas entre cámaras infrarrojas y RGBD para fusionar imágenes térmicas, RGB y RGBD, así como para registrar datos térmicos y de profundidad. Funcionalidades adicionales incluyen el manejo de usuarios, una GUI para visualización de los tres tipos de imágenes, el almacenamiento en una base de datos y la generación de reportes. Resultados: Además de las pruebas de integración para validar la funcionalidad de DepTherm, se realizaron dos pruebas cuantitativas para evaluar su precisión. Se encontró un error máximo de reproyección de 1,47±0,64 pixeles, mientras que el registro de un cubo con 11 cm de lado tuvo un error promedio máximo de 4,147 mm. Conclusiones: Las funcionalidades de la herramienta software DepTherm están enfocadas en facilitar las inspecciones termográficas capturando modelos 3D de las escenas con información térmica

Thermochromic liquid crystals as a temperature indicators

Byl proveden stručný přehled termochromních kapalných krystalů pro měření povrchové teploty. Praktický aspekt se zaměřil na získání a kalibraci křivky barevného odstínu a teploty pro různé úhly osvětlení a vertikální vzdálenosti osvětlení.A concise review of the application of thermochromic liquid crystals for surface temperature measurement was conducted. The practical aspect focused on obtaining a hue-temperature calibration curve for different angles of illumination and vertical distances of illumination, in order to evaluate of illumination source on accuracy of measurement

3D thermal monitoring of jointed rock masses through infrared thermography and photogrammetry

The study of strain effects in thermally-forced rock masses has gathered growing interest from engineering geology researchers in the last decade. In this framework, digital photogrammetry and infrared thermography have become two of the most exploited remote surveying techniques in engineering geology applications because they can provide useful information concerning geomechanical and thermal conditions of these complex natural systems where the mechanical role of joints cannot be neglected. In this paper, a methodology is proposed for generating point clouds of rock masses prone to failure, combining the high geometric accuracy of RGB optical images and the thermal information derived by infrared thermography surveys. Multiple 3D thermal point clouds and a high-resolution RGB point cloud were separately generated and co-registered by acquiring thermograms at different times of the day and in different seasons using commercial software for Structure from Motion and point cloud analysis. Temperature attributes of thermal point clouds were merged with the reference high-resolution optical point cloud to obtain a composite 3D model storing accurate geometric information and multitemporal surface temperature distributions. The quality of merged point clouds was evaluated by comparing temperature distributions derived by 2D thermograms and 3D thermal models, with a view to estimating their accuracy in describing surface thermal fields. Moreover, a preliminary attempt was made to test the feasibility of this approach in investigating the thermal behavior of complex natural systems such as jointed rock masses by analyzing the spatial distribution and temporal evolution of surface temperature ranges under different climatic conditions. The obtained results show that despite the low resolution of the IR sensor, the geometric accuracy and the correspondence between 2D and 3D temperature measurements are high enough to consider 3D thermal point clouds suitable to describe surface temperature distributions and adequate for monitoring purposes of jointed rock mass