Biomedical subjects

John Winder

Publications and source records attributed to John Winder.

3 recordsLinked to original sources

PubMed2005

Medical rapid prototyping technologies: state of the art and current limitations for application in oral and maxillofacial surgery.

PURPOSE: We describe state-of-the-art software and hardware requirements for the manufacture of high quality medical models manufactured using medical rapid prototyping. The limitations of medical models, the source of artefacts, and their physical appearance are illustrated along with remedies for their removal. MATERIALS AND METHODS: Medical models were built using predominantly stereolithography and fused deposition modeling at both institutions over a period of 6 years. A combined total of 350 models have been produced for a range of maxillofacial, neurosurgical, and orthopedic applications. Stereolithography, fused deposition modeling, computerized numerical milling, and other technologies are described along with computer software requirements. RESULTS: A range of unwanted artefacts that create distortions on medical models have been identified. These include data import, computed tomography gantry distortion, metal, motion, surface roughness due to support structure removal or surface modeling, and image data thresholding. The source of the artefact has been related to the patient, imaging modality performance, or the modeling technology. Discussion as to the significance of the artefacts on clinical use is provided. CONCLUSIONS: It is recommended that models of human anatomy generated by medical rapid prototyping are subject to rigorous quality assurance at all stages of the manufacturing process. Clinicians should be aware of potential areas for inaccuracies within models and review the source images in cases where model integrity is in doubt.

Artifacts↗

PubMed2005

Virtual surgical planning and CAD/CAM in the treatment of cranial defects.

The purpose of this work was to enhance the clinical outcome in the neurosurgical treatment of cranial defects and fibrous dysplasia. Cranial defects require repair using a variety of materials to protect the brain and provide a good cosmetic outcome for the patient. Virtual neurosurgery and CAD/CAM techniques have been employed to increase the implant 3-dimensional accuracy. The source data was 3D Computed Tomography scans. The CT scans were visualised using surface shading and rotation with volume rotation and re-sizing being used to review the complete data set. The volume data was manipulated using 3D image editing and surface modelling. Physical models of the patients' skulls were created using computed numerical milling which provided a physically accurate template for the production of a cranial implant. This has led to improved fitting for titanium plates requiring less theatre time and in the case of fibrous dysplasia a change in the operative technique from a two stage operation to one stage.

Computer-Aided Design↗

PubMed2004

Increasing face validity of a vascular interventional training system.

BACKGROUND: Many aspects of medical training take place on real patients in a live environment thus incurring risk. Apart from the obvious risks to patients there is the issue of X-ray exposure to both staff and trainees. Image quality used during interventional procedures is low to ensure minimum X-ray radiation dose. A virtual interventional system may be used to simulate the interventional cardiology training environment therefore reducing overall risk. The purpose of this project was to determine the appropriate image quality settings on a virtual training system to accurately simulate interventional cardiology and increase the face validity of the overall system. METHODS: Real image data was obtained from patients undergoing diagnostic interventional cardiology examinations in the Royal Victoria Hospital, Belfast. The images were obtained during catheter placement and contrast enhancement around the region of the heart. The diagnostic views were left anterior oblique, right anterior oblique, left lateral, caudal and the spider view. These five views were simulated on a virtual interventional training system (VIST, Mentice Medical Simulation AB, Sweden) by adjusting x-ray tube and table position at 20 different image quality settings. Signal to noise ratio and image contrast were measured for each of these views using soft tissue and vertebra. The results from the real image data and the VIST image data were compared. Calibration curves were compiled to determine the appropriate VIST image quality setting for each procedure. RESULTS: Average SNR ranged from 2.94 to 74.0 and IC ranged from 0.009 to 0.61 on the real image data. This indicates the very wide range of image quality encountered in interventional cardiology. Calibration curves for each view with the corresponding range of real patient image quality were produced. These calibration curves enabled the appropriate VIST image quality setting to be determined and therefore simulate the real examination image quality as closely as possible. CONCLUSIONS: The VIST system has been calibrated in terms of image quality for interventional cardiology examinations. This has increased the face validity of the system.

Cardiology↗