Dual-camera infrared guidance for computed tomography biopsy procedures

A CT-guided biopsy is a specialised surgical procedure whereby a needle is used to withdraw tissue or fluid specimen from a lesion of interest. The needle is guided while being viewed by a clinician on a computed tomography (CT) scan. CT guided biopsies invariably expose patients and operators to high dosage of radiation and are lengthy procedures where the lack of spatial referencing while guiding the needle along the required entry path are some of the diffculties currently encountered. This research focuses on addressing two of the challenges clinicians currently face when performing CT-guided biopsy procedures. The first challenge is the lack of spatial referencing during a biopsy procedure, with the requirement for improved accuracy and reduction in the number of repeated scans. In order to achieve this an infrared navigation system was designed and implemented where an existing approach was subsequently extended to help guide the clinician in advancing the biopsy needle. This extended algorithm computed a scaled estimate of the needle endpoint and assists with navigating the biopsy needle through a dedicated and custom built graphical user interface. The second challenge was to design and implement a training environment where clinicians could practice different entry angles and scenarios. A prototype training module was designed and built to provide simulated biopsy procedures in order to help increase spatial referencing. Various experiments and different scenarios were designed and tested to demonstrate the correctness of the algorithm and provide real-life simulated scenarios where the operators had a chance to practice different entry angles and familiarise themselves with the equipment. A comprehensive survey was also undertaken to investigate the advantages and disadvantages of the system

Progress in industrial photogrammetry by means of markerless solutions

174 p.La siguiente tesis está enfocada al desarrollo y uso avanzado de metodologías fotogramétrica sin dianas en aplicaciones industriales. La fotogrametría es una técnica de medición óptica 3D que engloba múltiples configuraciones y aproximaciones. En este estudio se han desarrollado procedimientos de medición, modelos y estrategias de procesamiento de imagen que van más allá que la fotogrametría convencional y buscan el emplear soluciones de otros campos de la visión artificial en aplicaciones industriales. Mientras que la fotogrametría industrial requiere emplear dianas artificiales para definir los puntos o elementos de interés, esta tesis contempla la reducción e incluso la eliminación de las dianas tanto pasivas como activas como alternativas prácticas. La mayoría de los sistemas de medida utilizan las dianas tanto para definir los puntos de control, relacionar las distintas perspectivas, obtener precisión, así como para automatizar las medidas. Aunque en muchas situaciones el empleo de dianas no sea restrictivo existen aplicaciones industriales donde su empleo condiciona y restringe considerablemente los procedimientos de medida empleados en la inspección. Un claro ejemplo es la verificación y control de calidad de piezas seriadas, o la medición y seguimiento de elementos prismáticos relacionados con un sistema de referencia determinado. Es en este punto donde la fotogrametría sin dianas puede combinarse o complementarse con soluciones tradicionales para tratar de mejorar las prestaciones actuales

Electromagnetic Tracking for Medical Imaging

This thesis explores the novel use of a wireless electromagnetic: EM) tracking device in a Computed Tomography: CT) environment. The sources of electromagnetic interference inside a Philips Brilliant Big Bore CT scanner are analyzed. A research version of the Calypso wireless tracking system was set up inside the CT suite, and a set of three Beacon transponders was bonded to a plastic fixture. The tracking system was tested under different working parameters including orientation of tracking beacons, the gain level of the frontend amplifier, the distance between the transponders and the sensor array, the rotation speed of the CT gantry, and the presence/absence of the CT X-ray source. The performance of the tracking system reveals two obvious factors which bring in electromagnetic interference: 1) metal like effect brought in by carbon fiber patient couch and 2) electromagnetic disturbance due to spinning metal inside the CT gantry. The accuracy requirements for electromagnetic tracking in the CT environment are a Root Mean Square: RMS) error of \u3c2 mm in stationary position tracking. Within a working volume of 120×120×120 mm3 centered 200 mm below the sensor array, the tracking system achieves the desired clinical goal