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PubMed1996

[Use of the computer in dentistry: video superimposition and facial reproduction using the expedience of the computer interface].

Both video superimposition and computer facial reproduction play a useful role in the process of identification, particularly in the early stages of an investigation or when other more definitive methods may not be available. Video superimposition combined with a computer overlay technique can be used to establish whether a skull outline matches an image of a missing person, being a photograph, slide or videoimage. A computer driven robot can be used to simplify the alignment of the skull with the position of the head on the image. Craniofacial or facial reproduction are used in both 2D or 3D to produce an image which can be used for identification purposes.

Computer Graphics↗
PubMed2003

Role of computer analysis in gastric cancer surgery: evaluation of the WinEstimate v. 2.5 computer program.

To identify the group of patients with gastric cancer who can benefit from extensive lymphadenectomy and to offer a rational approach to lymph node dissection, it is important to know the incidence of metastases at each lymph node station. A computer program was developed for assessment of lymph node involvement and survival time in each individual case according to preoperative variables. In patients who have undergone R0 resection with D2 lymphadenectomy, differences between the individual results generated by the computer and the actual data were compared. A cutoff point of 10% in the prediction of metastases was used as a positive result. The computer program made false predictions in 9% of patients for the pN status (3% lower and 6% higher than the actual status). Computerized prediction of 5-year survival was close to the rate calculated by the Kaplan-Meier method (55.5% vs 56.1%). Preoperative computer analysis of patient data and tumor characteristics offers a rational approach to individualizing tumor therapy] where the extent of lymph node dissection is tailored to the type, site, and stage of the tumor, thereby minimizing the disadvantages (morbidity, mortality) associated with the extensive operative procedure.

Female↗
PubMed2004

Some computational and algorithmic developments in computational mechanics of discontinua.

Discontinua simulations are becoming an important part of computational mechanics to the extent that computational mechanics of discontinua is becoming a separate sub-discipline of computational mechanics. Among the most widely used methods of computational mechanics of discontinua are discrete-element methods, combined finite-discrete-element methods and discontinuum deformation analysis methods. A range of key algorithmic procedures is common to most of these methods. These include contact detection, explicit solvers, fracture and fragmentation models, handling of complex geometric considerations when processing interaction in three dimensions (contact kinematics) and fluid coupling. In recent years, there have been major breakthroughs in almost all of these key algorithmic aspects. These include linear contact-detection procedures (NBS, C-grid), discretized contact solutions, fracture and fragmentation solutions, together with fluid pressure driven fracture process and three-dimensional explicit solvers incorporating finite rotations. Many of these breakthroughs have not yet been applied across the full range of relevant discontinuum problems. The major reason for this is that discrete-element method, discontinuum deformation analysis and combined finite-discrete-element method publications are spread over a wide range of specialist journals and conferences. Thus in this paper, the main features of a selection of algorithmic breakthroughs are reviewed for the first time, enabling researchers in different fields to apply these compatible developments to their specific applications.

Journal Article↗
PubMed1988

Psychology of computer use: V. Computer use and the experience of time.

To determine whether estimates of duration are altered when people use computers, 60 undergraduates solved easy or difficult single-solution anagrams presented on paper and by computer. Subjects who solved easy anagrams presented on paper underestimated the duration of time allowed for the task, while subjects who completed the anagrams presented by computer overestimated that duration. Also, subjects who solved difficult anagrams presented on computers solved significantly fewer anagrams than did subjects who solved difficult anagrams presented on paper. Results are discussed in terms of contradictory results of past research regarding perceived complexity of events in intervals and the interaction of task type and time estimation.

Data Display↗
PubMed1983

Computer applications in hospital pharmacy practice. I. Computer expectations/applications.

Following vendor selection of a pharmacy computer system, attention must be directed toward which computerized functions to include. Although most features are uniform among the various systems, a discussion is presented listing those applications considered the minimum acceptable for any hospital pharmacy computer system. The descriptions focus on computerization of those labor-intensive activities necessary to support drug distribution services. Computerized support of an intravenous (I.V.) admixture and unit dose program centers around label production and charging/crediting functions. Label production is used to generate a manual backup profile and unit dose cart fill list. The scope of information to include on I.V. and unit dose labels is described. Charging/crediting functions via computer are also discussed, with mention of free-form capabilities. Other computer applications mentioned include: medication profiling, drug interaction flagging, data confidentiality, census support, and hard copy reports. Feature selection depends on the aspects and unique needs that benefit most from computerization.

Accounting↗
PubMed1988

Computer corner #18. A computer program suitable for routine hip replacement follow up and clinical research.

A computer program was developed to facilitate routine follow up examination of patients with total hip replacements and to allow detailed analysis of the collected data for clinical research purposes. Information on more than 800 low friction arthroplasties has now been entered into the computer program. The system is versatile and can be modified to suit particular needs. The method of entering and recalling data can be learned rapidly by those unfamiliar with computers, however, analysis of the data requires advanced computer expertise. Hardware and software requirements for the program are listed at the end of this article.

Follow-Up Studies↗
PubMed1993

Features of computer language: communication of computers and its complexity.

Motivated by computer science, in particular, by applications to data security, electronic correspondence and cryptography, interactive proofs extend the 2000 years old, well established notion of mathematical proof. The key to these development is complexity which is defined as the minimum amount of a certain resource needed to complete a computational task. In this paper, the idea of an interactive proof system and its application in computer science is illuminated on everyday examples, without giving technical details.

Computer Security↗
PubMed2005

Preliminary investigation of computer-aided detection of pulmonary embolism in three-dimensional computed tomography pulmonary angiography images.

RATIONALE AND OBJECTIVES: We sought to develop a computer-aided diagnosis (CAD) system for assisting radiologists in the detection of pulmonary embolism (PE) on computed tomography pulmonary angiographic (CTPA) images. MATERIALS AND METHODS: An adaptive three-dimensional (3D) voxel clustering method was developed based on expectation-maximization (EM) analysis to extract vessels from their surrounding tissues. Using a connected component analysis, the vessel tree was reconstructed by tracking the vessel and its branches in 3D space. The tracked vessels were prescreened for suspicious PE areas using a second EM analysis. A rule-based false-positive (FP) reduction method was designed to detect true PE based on the features of PE and vessels. In this preliminary study, 14 patients with positive CTPA for PE were studied. CT scans were performed at 1.25-mm collimation using a GE LightSpeed CT scanner; eight of these patients also had extensive lung parenchymal or pleural disease. One hundred sixty-three emboli were identified by two experienced thoracic radiologists. The emboli identified by the radiologists were used as the "gold standard." For each embolus, the percent diameter occlusion (clot) and conspicuity of embolus (rating of 1 to 5, with 5 being the most conspicuous) were visually estimated. One hundred one emboli were identified in the six patients without lung diseases; 57 were proximal to the subsegmental and 44 were subsegmental. For the eight patients with lung diseases, 62 emboli were identified, of which 37 were proximal to the subsegmental and 25 were subsegmental. A computer-detected volume was counted as true-positive when it overlapped with an embolus volume identified by the radiologists. RESULTS: In the cases without lung diseases, if the PE had a conspicuity of >2 and only partially (20%-80%) occluded the vessel, our method detected 92.0% of proximal emboli and 77.8% of subsegmental emboli, with an average of 18.3 FPs/case. In the cases containing extensive lung disease, 66.7% and 40.0% of the PEs were detected with an average of 11.4 FPs/case under the same conditions. For the 14 PE cases, 13 of them were diagnosed as positive PE cases (case sensitivity was 92.9%). CONCLUSION: This preliminary study indicates that our automated method is a promising approach to CAD of PE on CTPA. Further study is under way to collect a larger data set and to improve the detection accuracy for PE, especially those with <20% or >80% occlusion, and for very subtle PE. A fully developed CAD system is expected to provide a useful aid for PE detection on CTPA.

Angiography↗
PubMed2006

[Computer-assisted positioning of the acetabular cup for total hip arthroplasty based on joint kinematics without prior imaging: preliminary results with computed tomographic assessment].

PURPOSE OF THE STUDY: Most navigation systems for computer-assisted total hip arthroplasty (THA) require prior computed tomography (CT) or acquisition of multiple bone landmarks on the pelvis. In order to avoid these problems, we developed a computer-assisted navigation system without CT based on a kinematic approach to the hip joint. The principle is to orient the cup in relation to the cone describing the hip joint range of motion. The purpose of this work was to analyze preliminary results. MATERIAL AND METHODS: Eighteen primary THA were implanted with the system (16 women, two men, mean age 68 +/- 7.8 years, age range 54-83 years, 18 degenerative hip disease). Two optoelectronic captors were fixed percutaneously on the pelvis and the distal femur. The acetabulum was prepared first followed by the femur using reamers and broaches of increasing size. The last broach placed in the femur was equipped with a large head adapted to the newly prepared acetabulum. The range of hip motion was recorded to determine the maximal range of motion cone. The acetabular cup was thus positioned in order the prosthesis range of motion included entirely the maximal range of motion of the hip joint. RESULTS: One patient fell three weeks after implantation causing posterior dislocation; there was no recurrence. The Postel-Merle-d'Aubligné score improved from 8 +/- 2.9 (range 3-12) preoperatively to 17 +/- 0.8 (range 16-18) at last follow-up. None of the patients complained about the captor insertion and there were no cases of hematoma or fracture. Operative time was 35-40 minutes longer for the first four cases and was progressively reduced 15-20 minutes for the last four cases. Mean leg length discrepancy was 5.6 +/- 7.5 mm (range 0-25) before implantation and 0.6 +/- 3 mm (range -5 to 10 mm) at last follow-up. CT-scan measurements revealed a mean anteversion of the femoral implant of 18.2 +/- 8.5 degrees (range 0-31). Anatomic anteversion of the cup (measured from the pelvis landmark and thus independently of the position of the pelvis) was 24.7 +/- 8.8 degrees (range 12-40). The sum of the femoral and anatomic acetabular anteversions was 43 +/- 13.1 degrees (range 22-71). Anteversions were 16 degrees for the cup and 16 degrees for the stem for the one case of dislocation. CONCLUSION: This method can be used in routine without lengthening operative time significantly. It safely controls leg length and helps position the cup. This study demonstrated that there is no ideal position for the cup which can be used for all patients. Because of the wide range of inclination and anteversion figures, half of the cases were outside the safety zone recommended by Lewinnek.

Acetabulum↗
PubMed2001

From cells to computers: computing with membranes (P systems).

The aim of this paper is to introduce to the reader the main ideas of computing with membranes, a recent branch of (theoretical) molecular computing. In short, in a cell-like system, multisets of objects evolve according to given rules in the compartments defined by a membrane structure and compute natural numbers as the result of halting sequences of transitions. The model is parallel, nondeterministic. Many variants have already been considered and many problems about them were investigated. We present here some of these variants, focusing on two central classes of results: (1) characterizations of the recursively enumerable sets of numbers and (2) possibilities to solve NP-complete problems in polynomial--even linear--time (of course, by making use of an exponential space). The results are given without proofs. An almost complete bibliography of the domain, at the middle of October 2000, is also provided.

Cell Membrane↗
PubMed2004

Gadolinium-enhanced computed tomography angiography in multi-detector row computed tomography: initial observations.

RATIONALE AND OBJECTIVES: The feasibility of using gadolinium contrast medium for computed tomography angiography (CTA) in multi-detector row computed tomography and the effect of contrast medium dilution was investigated. MATERIALS AND METHODS: Three pigs were each scanned in multiple sessions with injections of non-dilute and dilute contrast medium at a dose of 0.3 mmol/kg body weight. Non-spiral dynamic scanning at a fixed mid-abdominal aortic level and thoracoabdominal CTA were performed. RESULTS: The magnitude of peak aortic enhancement was not significantly different between dilute and non-dilute contrast medium injections (P = .88), but the former showed earlier enhancement (mean of 2.3 seconds sooner, P < .01) than the latter. CT angiography with gadolinium contrast medium showed much lower enhancement than iodine contrast medium, but small vessels were readily identifiable. CONCLUSION: Gadolinium contrast medium combined with multi-detector row computed tomography may provide clinically useful CTA. Dilution of contrast medium shortens the enhancement time but has little effect on the magnitude.

Angiography↗
PubMed2004

Assessment methodologies and statistical issues for computer-aided diagnosis of lung nodules in computed tomography: contemporary research topics relevant to the lung image database consortium.

Cancer of the lung and bronchus is the leading fatal malignancy in the United States. Five-year survival is low, but treatment of early stage disease considerably improves chances of survival. Advances in multidetector-row computed tomography technology provide detection of smaller lung nodules and offer a potentially effective screening tool. The large number of images per exam, however, requires considerable radiologist time for interpretation and is an impediment to clinical throughput. Thus, computer-aided diagnosis (CAD) methods are needed to assist radiologists with their decision making. To promote the development of CAD methods, the National Cancer Institute formed the Lung Image Database Consortium (LIDC). The LIDC is charged with developing the consensus and standards necessary to create an image database of multidetector-row computed tomography lung images as a resource for CAD researchers. To develop such a prospective database, its potential uses must be anticipated. The ultimate applications will influence the information that must be included along with the images, the relevant measures of algorithm performance, and the number of required images. In this article we outline assessment methodologies and statistical issues as they relate to several potential uses of the LIDC database. We review methods for performance assessment and discuss issues of defining "truth" as well as the complications that arise when truth information is not available. We also discuss issues about sizing and populating a database.

Algorithms↗
PubMed1999

Progression of maxillofacial squamous cell carcinoma evaluated using computer graphics with spiral computed tomography.

This report describes the appearance of maxillofacial squamous cell carcinoma in multiplanar (MPR) and three-dimensional (3D) images reconstructed from spiral CT using computer graphics and the importance of the computer software tools in permitting better visualization of the lesion. Two oral and maxillofacial radiologists and one neuroradiologist analysed the images. The usefulness of interactive reconstruction in the diagnosis, surgical planning and treatment evaluation, especially in the localization of the extent of these maxillofacial tumors, was demonstrated. Spiral CT-based computer graphics for displaying MPR and 3D images are an important adjunct in the evaluation of squamous cell carcinoma.

Aged↗
PubMed2003

Personal computer-based three-dimensional computed tomographic images of the teeth for evaluating supernumerary or ectopically impacted teeth.

This study describes the use of personal computer (PC)-based three-dimensional computed tomographic (3D CT) images in the evaluation of supernumerary and ectopically impacted teeth. Three selected cases were presented as examples of the more complex cases in which 3D CT imaging added information not readily available from periapical, occlusal, or panoramic radiographs. Patients were CT scanned from the occlusal plane to the periapical region of the impacted teeth. Digital Image and Communications in Medicine CT data were transferred to a personal laptop computer using a network line. 3D volume rendering was performed using PC-based volumetric analysis software. 3D CT-reformatted imaging of the teeth is a useful way to investigate and localize supernumerary or impacted teeth. Newer software that enables this investigation using a PC provides a relatively inexpensive way to carry out such investigations, making it easier for dental practitioners to request such investigations and to view the results in real time in their own offices.

Adolescent↗
PubMed1993

Variables affecting pulmonary nodule detection with computed tomography: evaluation with three-dimensional computer simulation.

To meaningfully evaluate factors determining the overall accuracy of computed tomography (CT) for identifying pulmonary nodules, computer-generated nodules were superimposed on normal CT scans and interpreted independently by three experienced chest radiologists. Variables evaluated included nodule size, shape, number, density, location, edge characteristics, and relationship to adjacent vessels, as well as technical factors, including slice thickness and electronic windowing. The overall sensitivity in identifying nodules was 62% and the specificity was 80%. On average, the observers identified 56, 67, and 63% of nodules on 1.5-, 5-, and 10-mm-thick sections, respectively (p = 0.037). Nodules were more difficult to identify on 1.5-mm-thick sections. On average, observers identified 1, 48, 82, and 91% of nodules < 1.5, < 3, < 4.5, and < 7 mm in diameter, respectively (p < 0.001). Other factors that made a significant contribution (p < 0.01) in identifying nodules, as determined by linear discriminant function analysis, included nodule location, angiocentricity, and density. We concluded that computer-generated nodules can be used to assess a large number of imaging variables. We anticipate that this approach will be of considerable utility in assessing the accuracy of interpretation of a wide range of pathologic entities as well as in optimizing three-dimensional scan protocols within the thorax.

Humans↗
PubMedDate not supplied

Methodologic trends in the healthcare professions: computer adaptive and computer simulation testing.

Assessing knowledge and performance on computer is rapidly becoming a common phenomenon in testing and measurement. Computer adaptive testing presents an individualized test format in accordance with the examinee's ability level. The efficiency of the testing process enables a more precise estimate of performance, often with fewer items than traditional paper-and-pencil testing methodologies. Computer simulation testing involves performance-based, or authentic, assessment of the examinee's clinical decision-making abilities. The authors discuss the trends in assessing performance through computerized means and the application of these methodologies to community-based nursing practice.

Clinical Competence↗
PubMed2007

Fluoroscopic computer-assisted pedicle screw placement through a mature fusion mass: an assessment of 24 consecutive cases with independent analysis of computed tomography and clinical data.

STUDY DESIGN: Observational matched cohort study with computed tomography (CT) analysis of pedicle screw placement. OBJECTIVE: Assess the clinical accuracy of computer-assisted fluoroscopy for the placement of thoracolumbar pedicle screws through a mature posterolateral fusion mass. SUMMARY OF BACKGROUND DATA: Pedicle screw placement through an amorphous posterolateral fusion mass intuitively carries a higher risk of pedicle wall violation. METHODS: Postoperative CT scans of 102 pedicle screws placed through a mature posterolateral fusion mass (n = 10 [T10-T12]; n = 92 [L1-S1]) were independently assessed and compared with a matched control (nonobscured anatomy) group. All screws were placed before any decompression using the FluoroNav system. RESULTS: In the fusion mass group, overall 81.4% of screws were completely within the pedicle. Seven medial and 12 lateral pedicle breaches occurred. Relative to the total number of screws, pedicle breaches were graded II (<2 mm) in 13.5%, III (2-4 mm) in 2.9%, and IV (>4 mm) in 2.0% of screws. The number and direction of pedicle breaches were not significantly different when compared with the control group. There were no clinically significant screw misplacements in either group. CONCLUSIONS: The use of computer-assisted fluoroscopy is safe and effective for the placement of thoracolumbar (T10-S1) pedicle screws through a posterolateral fusion mass without performing laminoforaminotomies.

Adult↗
PubMed2007

Increase of accuracy in intraoperative navigation through high-resolution flat-panel volume computed tomography: experimental comparison with multislice computed tomography-based navigation.

HYPOTHESIS: High-resolution imaging, as provided by flat-panel-based volume computed tomography (fpVCT), could increase navigation accuracy and could therefore improve image-guided procedures or make novel navigated surgery concepts possible. BACKGROUND: Intraoperative navigation is an accepted tool in head and neck surgery. However, its use is limited in the lateral cranial base because of its low surgical accuracy. Surgical accuracy is substantially influenced by the resolution of the underlying data set. The fpVCT offers a resolution of nearly two times higher than multislice computed tomography (MSCT). Target registration error (TRE), as a measurement for surgical navigation accuracy, should decrease when navigation is based on fpVCT data sets. METHODS: An acrylic glass phantom with 37 fiducial points was scanned in a current MSCT and in an experimental fpVCT. Both data sets were imported in an optical navigation system. Five fiducial points were used for registration, and seven points were used for measuring TRE. The distance between the indicated pointer tip and the corresponding fiducial point in data set was measured as TRE. Registration and TRE measurement were repeated five times for each computed tomographic data set. Average TREs were calculated, and results were compared using t-test. RESULTS: The average TRE using MSCT (0.82 mm [standard deviation, 0.35 mm]) was significantly higher than that using fpVCT (0.46 mm [standard deviation, 0.22 mm]) (p < 0.01). CONCLUSION: Submillimeter surgical navigation accuracy is possible using high-resolution fpVCT. This could be highly beneficial in cranial base surgery navigation.

Humans↗