Workflow Driven Decision Support Systems: A case of an intra-operative visualization system for surgeons

Inadequate visualization during Minimally Invasive Surgeries (MIS) has led several technology research labs to develop decision support systems such as Intra-operative Visualization Systems (IVS). IVS focuses on providing surgeons with real-time imaging support to improve task visualization and navigation. Though exciting, this emerging field also presents challenges in terms of design, development, implementation and integration of various technologies in the surgical workplace. While developing a technically robust IVS which integrates various imaging sources may help visualizing the patient data, it may not serve its true purpose: to adequately support surgeons in making the right decisions. Development of IVS should therefore be not just “technology intensive”; but “Knowledge Intensive Visualization System (KIVS)”. This means that these systems should aim to provide the knowledge to make informed decisions by providing the surgeon with the necessary patient information. This thesis is an example of the role design as a discipline can play in guiding the user-centered technological innovation in the area of medical informatics, especially in the case where the development depends on creating collaborative design between different scientific disciplines: surgical, technological (medical informatics) and design. Visualization of the patient information which supports surgical decision making in KIVS is dependent on knowledge of surgical workflow- which means knowledge of how surgeons solve problems and make decisions while performing the procedure. Surgical workflow depends on a dynamic information flow between the system, the surgeon, the patient, and the surgical team. Surgical workflow is also linked in time over the three surgical phases: pre-operative (before surgery), intra-operative (during surgery), and post-operative (post surgery). This thesis focuses on answering the following research questions: (a) What are the constituents or task boundaries of the surgical workspace that influence the surgical workflow or the surgical problem-solving process? (b) How can the knowledge of the surgical workflow be incorporated into the design of KIVS so as to improve decision-making and thus the performance of the surgeons?(c) In a multidisciplinary development team of surgeons, technology engineers and designers, what steps are required in the KIVS development process to facilitate collaborative design? Based on empirical studies with surgeons, this thesis proposed a design framework called “Workflow-centered design framework”. This framework assists in analyzing the surgical workflow which eventually leads to the development of the knowledge repository of surgical procedure, information and design requirements for the KIVS. This framework has been applied to support workflow driven development of two KIVS prototypes taking a case of upcoming MIS to treat cancer in liver called Radio frequency Ablation (RFA). These prototypes have been developed involving real-time image fusion between imaging modalities such as intra-operative Ultrasound (US) and pre-operative Computerized Tomography (CT) scan. The results from the evaluative study showed significant improvements in the performance of expert intervention radiologists and medical students while performing RFA using KIVS compared to US. In particular, intra-operative planning time and task accuracy of hitting the right tumor in the center showed significant improvement. The findings demonstrated the importance of workflow driven patient data visualization in improving surgical decision making. The framework proposed in this thesis serves as a means to generate the scientific knowledge required to drive user-centered development of KIVS. The contribution of this thesis is at three levels: - The framework proposed in this thesis contributes to design and ergonomics literature as a practical example of application of user centered design to drive innovative technological development of KIVS for complex workspaces such as the surgical theatre. - It contributes to the medical informatics by integrating cognitive theories as a foundation which guides the development of KIVS. - The KIVS prototype serves as a development aid to guide future technological innovation in the area of intra-operative visualization system for RFA and for MIS in general.Product Innovation ManagementIndustrial Design Engineerin

The effect of boundary conditions on the failure of thin plates subjected to impulsive loading

Bibliography: leaves 64-65.This report presents the results of an investigation into the effects of edge boundary conditions on the failure of thin plates subjected to impulsive loading. In previous investigations the discrepancy between experimental results and theoretical solutions and effects observed at the edges of deformed plates have brought the method of securing the plate into question. This investigation examines the effect of edge boundary conditions by comparing the results of previous experiments where the plates were secured by clamping - with experiments where the plates are built-in (integral) with their supports

The Resection Map: A proposal for intraoperative hepatectomy guidance

Objective - To propose a new concept of an intra-operative 3D visualisation system to support hepatectomies. This system aims at improving the transfer of pre-operative planning into the intra-operative stage, both in laparoscopic and open approaches. Materials and methods - User (surgeon) centred developmental process to identify the surgical requirements is applied. The surgical workflow of hepatectomy is analyzed, including observations of liver surgeries and focus group sessions. Based on this analysis, specifications for the “ResectionMap” are defined. A first implementation is developed, and preliminary clinical acceptance results are gathered. Results - Control of main veins and tumour margins are the two critical aspects. The “Resection Map” provides an intuitive visualisation of structures nearby the resection plane without any registration to the patient space. The first prototype subjectively increases the surgeon’s confidence and orientation, but it should be further developed for non anatomical resections. Conclusions - The ResectionMap is proposed as a pragmatic solution to enhance liver resection accuracy and safety.Product Innovation ManagementIndustrial Design Engineerin