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The extraction and display of 3-D information using modern computer graphic equipment in the electron microscope is presented. Thick specimens were imaged at 400 kV. Modelling of vectors and the tilting of surfaces is discussed as is the accuracy of reconstructions.
Implementation of newly developed computer modelling techniques and computer graphics displays and software have greatly aided the orthopedic design engineer and physician in creating a custom implant with good anatomic conformity in a short turnaround time. Further advances in computerized design and manufacturing will continue to simplify the development of custom prostheses and enlarge their niche in the joint replacement market.
Hydroxyapatite (HA) and beta-tricalcium phosphate (TCP) were studied by computer graphics with a personal computer. Crystal models of fluoridated hydroxyapatite and fluorapatite, in which F- ions are substituted into some or all OH- positions, were also drawn. Data on the structural coordinates of the hydroxyapatite and beta-TCP crystals were put into a protein graphics program in Angstrom units. The connection of each element, with front and rear, was displayed by the shade-line erasing method, and the solidity of the image was expressed by the degree of lightness from the light source. The colour tint was obtained by the Raster graphics method. A fine picture can be obtained with the photo program. Rotating the graphics freely around the X, Y, and Z axes gives a view from any direction. The computer graphics demonstrated visually that F- ions contribute to stabilize the hydroxyapatite crystal and that beta-TCP has an unstable structure due to 0.5 probability of Ca2+ ions and [PO4-Ca-Ca-Ca-PO4] zigzag chain.
This article presents examples of current technologies in computer graphics as applied to foot and ankle surgery. Presently, there are two areas of great potential in computer graphics: (1) preoperative surgical planning, and (2) computer-aided design and manufacturing of custom implants.
We have developed a stereotactic computer graphic system with brain maps that runs on a personal computer. This system consists of three parts: 1. firmware for dizitizing radiological films with a TV camera or scanner (when digital image is not directly obtained from floppy disks); 2. software for introducing or processing brain maps by matching them with CT or NMR images; 3. hardware. Our system is designed to: 1. recognize the relevant frame points and calculate targets, their volume and surgical instrument trajectory; 2. match between brain maps of an ideal brain and patient's CT or NMR images with visible and invisible pathology; 3. monitor during surgery the position of the surgical instrument or target modification. The whole procedure and processed images are stored in a data-base for further study.
Advanced computed tomographic and computer graphic techniques enhance diagnostic accuracy and offer the means by which three-dimensional operative planning can be achieved. These techniques have been used to diagnose hip pathology, rehearse and evaluate surgical plans, assess postoperative results, and design individualized prostheses.
The application of computer graphics for detection of myocardial infarction is reviewed and a special method is described. It is based on construction of two isointegral maps (Q wave map and ST segment map) realized in contour representation and using the Selvester distribution of the left ventricle.
In this paper we present the aspect of a mandibular giant cell granuloma in spiral computed tomography-based three-dimensional (3D-CT) reconstructed images using computer graphics, and demonstrate the importance of the vascular protocol in permitting better diagnosis, visualization and determination of the dimensions of the lesion. We analyzed 21 patients with maxillofacial lesions of neoplastic and proliferative origins. Two oral and maxillofacial radiologists analyzed the images. The usefulness of interactive 3D images reconstructed by means of computer graphics, especially using a vascular setting protocol for qualitative and quantitative analyses for the diagnosis, determination of the extent of lesions, treatment planning and follow-up, was demonstrated. The technique is an important adjunct to the evaluation of lesions in relation to axial CT slices and 3D-CT bone images.
This paper has aimed to give the reader an overview of the use of computer graphics in protein modeling. To judge the power of these systems the reader should take the opportunity of visiting a laboratory engaged in this research. It is hoped that one message has been made clear in this paper, that is, computer graphics is a powerful tool for molecular modeling that will be of great value to all groups involved in the design of novel polypeptides and other biologically active molecules.
Display systems based on conventional computer graphics cards are capable of generating images with about 8-bit luminance resolution. However, most vision experiments require more than 12 bits of luminance resolution. Pelli and Zhang [Spatial Vis. 10 (1997) 443] described a video attenuator for generating high luminance resolution displays on a monochrome monitor, or for driving just the green gun of a color monitor. Here we show how to achieve a white display by adding video amplifiers to duplicate the monochrome signal to drive all three guns of any color monitor. Because of the lack of the availability of high quality monochrome monitors, our method provides an inexpensive way to achieve high-resolution monochromatic displays using conventional, easy-to-get equipment. We describe the design principles, test results, and a few additional functionalities.
An interactive computer-graphics model of the mechanical interaction between the structural components of a Hill-type muscle model is presented. The model allows the length, velocity, and force in the contractile component, parallel elastic component, and series elastic of a generic (normalised) muscle-tendon complex to be computed from input defining instantaneous muscle stimulation and muscle-tendon length. By altering model inputs and model parameter values the user can observe corresponding model behaviour in schematic and graphical form. In this paper a general description of the model is provided together with examples of how the model can be used to simulate different contractile conditions. It is intended that the model will serve as a useful tool for demonstrating the behaviour of Hill-type muscle models.
We developed a pre-operative simulation and intra-operative navigation system with three-dimensional computer graphics (3D-CG). Because the 3D-CG created by the present system enables visualization of lesions via semitransparent imaging of the scalp surface and brain, the expected operative field could be visualized on the computer display pre-operatively. We used two different configurative navigators. One is assembled by an arciform arm and a laser pointer. The arciform arm consists of 3 joints mounted with rotary encoders forming an iso-center system. The distal end of the arm has a laser pointer, which has a CCD for measurement of the distance between the outlet of the laser beam, and the position illuminated by the laser pointer. Using this navigator, surgeons could accurately estimate the trajectory to the target lesion, and the boundaries of the lesion. Because the other navigator has six degrees of freedom and an interchangeable probe shaped like a bayonet on its tip, it can be used in deep structures through narrow openings. Our system proved efficient and yielded an unobstructed view of deep structures during microscopic neurosurgical procedures.
A method for estimating the locations of muscle origins and insertions from the measurement of surface landmarks was evaluated using two indirect accuracy tests and a three-dimensional computer graphics program. For each of four lower extremity anatomical segments, a least-squares technique was used to map the measured locations of three landmark targets to their anatomically based locations. The residual errors, obtained from the applications of the least squares, supplied the first indirect accuracy test. These residual errors were between 6 and 12 mm for the four anatomical segments when averaged over ten subjects. The second indirect accuracy test was conducted by comparing the predicted locations of end points on two adjacent segments forming a joint. Errors in aligning adjacent end points were between 12 and 29 mm for three anatomical joints when averaged over ten subjects. A three-dimensional computer graphics program was developed by the authors and demonstrated that the static testing techniques alone were insufficient to evaluate the quality of the muscle origin and insertion estimates. Any evaluation of muscle lengths, velocities and lines-of-action from surface landmarks should examine the estimates made from motion data, and should address both the ability of the model to fit the subjects as well as model's ability to represent the geometry of the musculoskeletal system.
AIM: To improve the pre-operative planning of interventional procedures in thorax surgery different methods of computer-graphical visualization of intrapulmonary lesions and adjacent anatomical structures based on CT and MR data were realized and compared to each other. DESIGN: In 21 patients with intrapulmonary lesions the image data was segmented by interactive and automatic algorithms and different reconstruction techniques were applied (maximum intensity projection; color-encoded and transparent surfaces; volume rendering). Based on these three-dimensional reconstructions, different views from arbitrary perspectives (including simulated endoscopic images) were generated and animated film sequences of the 3D scene were displayed with 30 frames/second. RESULTS: For all patients under review, a high-quality presentation of the relevant structures was obtained by use of the applied computer-graphical techniques. Even combinations of different visualization methods in one image can be generated with the software we developed. CONCLUSIONS: The various methods for image segmentation allow a fast and comfortable processing even of large data sets. The calculated values of tumor surface and volume can be used for quantitative studies and therapy control. The planning of surgical and interventional procedures can be supported by the simultaneous visualization of the intrathoracic lesion and the surrounding structures.
We have developed a computer graphics program system for the schematic representation of several protein secondary structure analysis algorithms. The programs calculate the probability of occurrence of alpha-helix, beta-sheet and beta-turns by the method of Chou and Fasman and assign unique predicted structure to each residue using a novel conflict resolution algorithm based on maximum likelihood. A detailed structure map containing secondary structure, hydrophobicity, sequence identity, sequence numbering and the location of putative N-linked glycosylation sites is then produced. In addition, helical wheel diagrams and hydrophobic moment calculations can be performed to further analyze the properties of selected regions of the sequence. As they require only structure specification as input, the graphics programs can easily be adapted for use with other secondary structure prediction schemes. The use of these programs to analyze protein structure-function relationships is described and evaluated.
GOAL: A computer graphics method that permits the reconstruction, visualization and measure of the vertebral deformities of the scoliotic spine is presented. MATERIALS: Medical imaging techniques utilizing computerized tomography is at the foundation of the reconstruction technique. The studied morphometric parameters are: 1) vertebral body wedging, 2) transverse and spinous process orientation and dimensions and 3) bilateral variation of pedicular dimensions. RESULTS: The reconstructed specimen showed the usefulness of this technique for visualizing and measuring vertebral deformities. Preliminary results seem to be in agreement with the literature concerning the deformities of scoliotic vertebrae. CONCLUSION: This tool will be useful in morphometric investigations for the evaluation of the deformations of scoliotic vertebrae.
A computer-graphic-based pattern-recognition study of two series of 5-ethyl-5-substituted barbiturates has been undertaken in an attempt to find a correlation between molecular conformation and convulsant and anticonvulsant activity. Studies of a first (trial) set of barbiturates related to pentobarbital revealed a region of space in which at least one low-energy conformation of the hydrocarbon side chain of each of the anticonvulsant barbiturates resides. Another region was occupied by a low-energy conformation of each of the convulsant barbiturates. These regions of space are, thus, possible pharmacophores for convulsant and anticonvulsant activity. Analysis of a second (test) set of barbiturates related to phenobarbital has shown that the activities and structures of these molecules are consistent with the above model. These pharmacophores thus provide a basis for the design of rigid, new analogues with potent convulsant or anticonvulsant activities.
The application of computer-based solid modeling techniques to human anatomy shows great promise for enhancing surgical instruction and research. Such advances will directly benefit patient care. The increasing availability of powerful modeling programs for the microcomputer and the interactive peripheral technologies make the delivery of this new modality practical at the present time. We continue to refine our methodology for producing accurate and esthetic anatomic models and have developed a technique for three-dimensional "sculpting" of elongated structures. We continue to explore the possibility of using sectional scanning data to create anatomic images. Several applications have been described, ranging from surgical simulations to a ballistic injury model, in order to indicate the potential scope of this powerful technology.