Computer-based Planning Research Articles

Policy, Practice and Education 2005: Computer-based cmps

Belton J. Developing a computer-based clinical management plan for supplementary prescribing. Nurse Prescribing 2005; 3(2): 76–78.

Developing a computer-based clinical management plan for supplementary prescribing

Supplementary prescribing was introduced in April 2003 with the vision of reducing waiting times, improving patient care and easing the burden of doctors. However, one of the barriers to fully utilizing supplementary prescribing is the time required to create a clinical management plan. With this in mind, in July 2004 Ealing PCT sought to create a template to use with IT clinical systems, in particular with the EMIS clinical system used in general practice. This article details the ideas behind, and the development of, a computer-based CMP for Ealing PCT.

COMPUTER-BASED SURGERY PLANNING FOR LIVING LIVER DONATION

The aim of this project is computer-based planning of a partial organ resection for three dimensional visualisation of anatomical structures and volumetric estimations. Using quantitative parameters for the estimation of the operation risk, the selection of patients can be further objectified. Another important effect of this project is support for surgical interventions by predefinition of different operation scenarios. All preoperative analysis results are based on tomographic images acquired during the clinical routine. In the end, the integration of planning results into the operation theater as well as into the clinical workflow is part of this project. Surgical strategy is determined by the exact location of the tumor, the respective donor liver part, and the proximity of supporting and draining vessels. Depending on the acquired images, the portal, hepatic, arterial and biliary systems may be analyzed. Therefore, fundamentals for the qualitative and quantitative analysis of images have been developed and implemented since the beginning of the project. The qualitative aspects are, e.g., the three dimensional visualisation of vessel structures, tumors, the security margin and the organ itself. These were evaluated for use in the clinical routine. Preoperatively, the operation strategy is planned by segmenting the important anatomical structures and defining the different vessel systems using a special operation planning software. The visualisation and volumetric results can be visualised and adapted during surgical intervention with the help of a beamer and a touchscreen monitor installed above the patient. In living donor liver transplantation (LDLT) the most important factor is to ensure that the anatomy of the donor patient allows surgical splitting of the liver. Also, a volumetric analysis of the donor liver is of interest to achieving less complicated surgery. Actually, all LDLTs performed in our Surgical Clinic are supported by this operation planning system.

A 3D computer graphics approach to brachytherapy planning.

Intravascular brachytherapy (IVB) can significantly reduce the risk of restenosis after interventional treatment of stenotic arteries, if planned and applied correctly. In order to facilitate computer-based IVB planning, a three-dimensional reconstruction of the stenotic artery based on intravascular ultrasound (IVUS) sequences is desirable. For this purpose, the frames of the IVUS sequence are properly aligned in space, possible gaps inbetween the IVUS frames are filled by interpolation with radial basis functions known from scattered data interpolation. The alignment procedure uses additional information which is obtained from biplane X-ray angiography performed simultaneously during the capturing of the IVUS sequence. After IVUS images and biplane angiography data are acquired from the patient, the vessel-wall borders and the IVUS catheter are detected by an active contour algorithm. Next, the twist (relative orientation) between adjacent IVUS frames is determined by a sequential triangulation method. The absolute orientation of each frame is established by a stochastic analysis based on anatomical landmarks. Finally, the reconstructed 3D vessel model is visualized by methods of combined volume and polygon rendering. The reconstruction is then used for the computation of the radiation-distribution within the tissue, emitted from a beta-radiation source. All these steps are performed during the percutaneous intervention.

Registration of Biplane Angiography and Intravascular Ultrasound for 3D Vessel Reconstruction

If planned and applied correctly, intra-vascular brachytherapy (IVB) can significantly reduce the risk of restenosis after interventional treatment of stenotic arteries. In order to facilitate computer-based IVB planning, a three-dimensional reconstruction of the stenotic artery based on intravascular ultrasound (IVUS) sequences is desirable. To attain a 3D reconstruction, the frames of the IVUS sequence are properly aligned in space and completed with additional intermediate frames generated by interpolation. The alignment procedure uses additional information that is obtained from biplane X-ray angiography performed simultaneously during the capturing of the IVUS sequence. After IVUS images and biplane angiography data are acquired from the patient, the vessel-wall borders and the IVUS catheter are detected by an active contour algorithm. Next, the twist between adjacent IVUS frames is determined by a sequential triangulation method combined with stochastic analysis. The above procedure results in a 3D volume-model of the vessel, which also contains information from the IVUS modality. This data is sufficient for computer-based intravascular brachytherapy planning. The proposed methodology can be used to improve the current state-of-the-art IVB treatment planning by enabling computerized dosage computations on a highly accurate 3D model.

Evaluation of deformable models for femoral neck surgery

Objective: Using fluoroscopic images alone, it is difficult to guarantee that screws are positioned within the femoral head and neck. This study evaluates whether the introduction of deformable 3D models limiting the planning and navigation space is a helpful approach to minimizing the incidence of misplaced screws, thereby enhancing patient safety.Background: Even though a screw may appear to lie within the femoral head and neck on fluoroscopic images, this may not, in fact, be the case. This is a particular problem for interventions such as fixation of a slipped femoral head or osteosynthesis of the femoral neck, where screws must be set close to the cortical bone without penetrating the joint or injuring the cortex of the femoral neck.Methods: A system was developed which permits computer-based planning and navigation of screws for femoral neck fracture fixation based on fluoroscopic images. Different approaches were employed which either a) make use of a deformable model adapted to the femoral head/neck, constraining the screw positions within this model; or b) allow the user to position the screws with or without geometrical constraints on the X-rays while maintaining parallelism of the screws. All designs were evaluated and compared by 7 test users using integral projection X-rays calculated from the CT dataset. Results were checked using a 3D model of the bone, also calculated from the CT dataset.Results: Positioning screws using the deformable model resulted in a significantly smaller distribution of screw tip locations and no penetrations into the hip joint, in contrast to the other approaches where up to 11% of screws were misplaced.Conclusions: Constraining the planning and navigation space by means of a deformable model allows better control of screw positioning and thus increases the chances of a successful intervention. In particular, CAS systems allowing for virtual fluoroscopy should consider supporting this planning approach.

23.2: A High Resolution Stereoscopic Computer Projection Display For Surgical Planning

AbstractThis paper details the construction of a high resolution, stereoscopic rear‐projection display specially optimized for collaborative, computer‐based surgical planning. The projection display was designed to address a number of drawbacks that exist in the use of other, more general‐purpose projection displays for this task

Graph-based set-up planning and tolerance decomposition for computer-aided fixture design

Set-up planning plays an important role in integrating design with process planning and fixture design. Its main task is to determine the number and sequence of set-ups, and select locating datum, machining features and operations in each setup. Computer-based set-up planning may be used to generate automatically a setup plan based on tolerance analysis for minimizing locating error, calculating machining error stack-up and improving CAD/CAPP/CAFD (Computer-aided Fixture Design) integration efficiency. Most of the current set-up planning systems were based on empirical methods (such as rule and knowledge base) and their applications background was plus/minus a dimensioning and tolerancing (GD&T) scheme. Today, more and more industries are using a true positioning Geometric Dimensioning and Tolerancing (GD&T) scheme in design and manufacturing. To support this requirement, this paper presents an analytical set-up planning approach with three techniques, (1) an extended graph to describe a Feature and Tolerance Relationship Graph (FTG) and a Datum and Machining Feature Relationship Graph (DMG), which could be transferred to an analytical computer model; (2) seven set-up planning principles to minimize machining error stack-up under a true positioning GD&T scheme; and (3) tolerance decomposition models to partition a tolerance into interoperable machining errors, which could be used for locating error analysis or for feedback to design stage for design improvement. These techniques are implemented in a computer system and it is integrated with a commercial CAD/CAM system to support an automobile manufacturing enterprise in fixture design and production planning.

Hochdosierte stereotaktische Einzeitbestrahlung mit kurativer Intention bei peripherem Bronchialkarzinom1

In peripheral non small cell lung cancer without metastasis, surgical resection achieves 5-year survival rates of at least 65%. In functionally inoperable patients radiation therapy offers the second best changes. However, in cases of severe emphysema with severely limited lung function even conventional radiation therapy is prohibited because of possible fibrotic reactions of the lung parenchyma. For such patients high dose rate stereotactic one-time radiation therapy may be an option. According to the study protocol of the DKFZ Heidelberg a dose rate of 24 Gy at the iso-center is applied with the linear accelerator in a single session. The recognisable tumour is irradiated with 22 Gy (90% isodose included). 20 Gy are applied to the tumour plus 6 millimeters safety margin. Prerequisites of such a therapy are a detailed computer-based planning using CT scans and an exact positioning with immobilisation of the patient. The irradiation is ideally performed under general anesthesia with high-frequency jetventilation to avoid movements due to breathing. We report on this new therapeutic modality in a patient with lung emphysema having a T2 tumour.

Approach to computer-based medication planning and coordination support in intensive care units

Due to more and more complex diagnosis and therapy measures, the critical care of patients requires an extensive work organisation which comprises patient, doctors, nurses and external services (e.g., central laboratory). In this organisation, the documentation plays a major role for the planning and coordination of work procedures and information flow within the medical staff. Various studies in intensive care units (ICU) reveal that the complex work organisation and the related information flow are faulty. Breakdowns are often caused by a lack of coordination between doctors and nurses and by poor transparency of work procedures. A typical example is the incorrect application of a doctor's medication orders by a nurse because she might have overseen a plan modification. This intransparency increases the strain on the medical staff and might result in critical effects on the patient. One approach to design a computer support for medication planning as well as the coordination when executing medication plans is given by work flow models. This paper shows that work flow models could be used to improve deficiencies in medication planning and coordination. Furthermore, it is demonstrated how such a support can be mediated to the user through an appropriately designed user interface.

Optimal Sizing of Flood Damage Reduction Measures Based on Economic Efficiency

A computer-based planning methodology for optimally sizing flood dam age reduction systems is presented. The decision variables are the size of each structural component of the system, such as storage capacity for reservoirs and flow capacity for channel improvements, and the choice of which non-structural plan to im plement in various regions of the floodplain. The decision criterion is to minimize total system cost, which is the sum of the discounted annual cost of implementing and maintaining each measure and the residual expected annual flood damages. A hydrologic and economic simulation model is combined with a search algorithm. The simulation model incorporates procedures for determ ining the total economic cost for a specified plan. The optimization algorithm iteratively executes the simulation model in an automated search for the optimum plan.

Optimization of process sequences considering prismatic workpieces

In the field of process planning most of the working time is spent on the following activities: machine tool and tool assignment, determination of the set-up and process sequence, definition of tool paths and optimization of cutting parameters. The quality of these activities substantially influences the manufacturing cost, which is to be minimized. The more complex the planning task, the more difficult it is for the planner to work out an optimal solution within a reasonable time. This article describes how the process planning of complex workpieces for drilling and milling can be optimized by applying a set of modified algorithms known from the field of combinatorial search problems. The data needed for the optimization process is retrieved from a feature-based CAD-model. The intention of the presented approach is to assist the human process planner with a computerbased planning tool in order to fulfil the above-mentioned activities more efficiently when a certain degree of complexity is reached.

Assessment of situated learning using computer environments

Based on a theory of situated learning, assessment must emphasize process as much as product. Assessment must move away from a linear additive model, accepting at the outset the complex, nonlinear, and possibly chaotic nature of real learning. Assessment must adapt to and take advantage of students working with technologies that extend their perceptual and problem-solving capacities beyond what they could do alone. To illustrate these points, several assessment examples are given, including a computer-based planning assistant for a videodisc mathematics and science video, suggestions for computer-based portfolio assessment, and speculations about embedded assessment of virtual situations. In all cases, the theory of situated learning emphasized perception over memory and the codetermined nature of learning and thinking.

Development of a Computer-Based Oil Spill Planning and Management Program for the Western Mining Corporation (Petroleum Division) Airlie Concession Area

Development of a Computer-Based Oil Spill Planning and Management Program for the Western Mining Corporation (Petroleum Division) Airlie Concession Area

Field evaluation of a computer-based career planning system

Field evaluation of a computer-based career planning system

Dimensions of I/S Planning and Design Aids: A Functional Model of CASE Technology

Information technology is playing an increasingly integral role in the competitive strategies of many organizations. As this trend continues, it is not surprising that there is growing emphasis on the ability of organizations to plan, design and implement critical information systems. A major strategy to improve the effectiveness of these processes is the use of computer-based planning and design aids. However, there is little empirical evidence that using this technology provides a significant performance impact. One factor limiting research on the impact of technology on planning and design is the manner in which this technology has been conceptualized for measuring usage behavior. This research develops a functional model of I/S planning and design support technology that distinguishes three general functional dimensions: Production Technology, Coordination Technology and Organizational Technology. An empirical analysis is used to test the robustness of the proposed model and its ability to discriminate among current design aids in a meaningful way. Implications for the use of this model in the study of I/S planning and design processes are discussed.

Netform Modeling and Applications

Many real-world applications have profited from netform innovations in both modeling and solution strategies. Practical experience shows that advances in netform modeling and solution strategies overcome many of the difficulties in conceptual design and problem solving of previous approaches to system optimization. Moreover, they provide the type of technologies required of truly useful decision-planning tools, technologies that facilitate modeling, solution, and implementation. The ultimate test and worth of computer-based planning models, however, depends on their use by practitioners. In this tutorial, we show how certain algebraic models can be viewed graphically using netform modeling and describe several large practical problems we have solved. Some of our insights can make it easier for practitioners to take advantage of these technologies.

Synthesis of operating procedures for complete chemical plants—III. Planning in the presence of qualitative, mixing constraints

A nonlinear planning methodology for handling qualitative mixing constraints is presented. It is intended to account for operational specifications prohibiting the mixing of two or more chemical species which form undesirable or potentially dangerous mixtures. The approach is based on the concept of the planning island and several algorithms derived from graph theory. The methodology is provably correct and all stated constraints are satisfied, thus ensuring that only feasible operating procedures are automatically synthesized. The methodology has been successfully applied to two industrial case studies: (a) the catalyst regeneration of powerforming reactors in a petroleum refinery; and (b) the planning of recovery procedures from faults in an ethylenediaminetetraacetic acid (EDTA) plant. The synthesis of operating plans for complete chemical plants is an interesting problem and one that has many practical applications. The thrust of a computer-based planning methodology should be toward increased automation, improvement in the efficiency of planning (planning should be achieved in polynomial time, wherever possible) and guarantees that the planning methodology produces correct (feasible) plans. It is also desirable that the plans generated are optimal, or at least cost efficient in their implementation. In developing this methodology, we have addressed the first three of these considerations within a modelling framework that is easy-to-use, menu-driven and which utilizes models with which process engineers are generally familiar. There has been an implicit tradeoff between safety (correctness) and optimality. Future work should address the issue of the completeness of the methodology (i.e. if a feasible plan exists, it will be found) which can not be currently guaranteed without the exhaustive (and practically infeasible) generate-and-test approach.

A FINANCIAL PLANNING MODEL FOR A BRITISH UNIVERSITY

This paper describes a computer-based planning model using the FCS-EPS decision support system to provide a deterministic simulation of the financial flows of a British university over the period 1986–87 to 1990–91. In discussing the model's design, attention is focused upon the validity for universities of various notions of accounting surplus and deficit. Regarding the implementation of the model, the centre of concern is with sensitivity analysis. In the concluding section, the model is placed in the context of related studies in the UK and America.

Experimental determination of cascade parameters of a hearing-aid microphone via the two-load method.

Presented in this article is a computer-aided experimental method for obtaining the cascade parameters of the two-port model of a miniature hearing-aid microphone. The method is an adaptation of the "two-load" method [D.P. Egolf and R.G. Leonard, J. Acoust. Soc. Am. 62, 1013-1023 (1977)] to acoustoelectric, rather than electroacoustic, transducers. The cascade parameters of a particular microphone, determined by this method, were within 2.5 dB of the manufacturer's published open-circuit sensitivity data. In an attempt to further verify the numerical cascade-parameter data, a two-port model of the microphone was used to simulate experimental voltages developed across two different complex electrical load impedances attached to the microphone. The results showed experimental/simulation differences of no greater than 3.0 dB at any frequency. The two-port microphone model and associated cascade parameters are currently being incorporated into a computer-based plan for mathematical simulation of an entire in situ hearing aid.