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PubMed1998

Computer-assisted spine surgery.

The aim of this study was to improve the reliability of pedicle screw insertion. Transpedicle screw insertion may cause neurological, vascular, and mechanical complications. Previous studies of surgical procedures have shown a significant rate of incorrect placement of the screw ranging from 10 to 40%. A new technique that combines preoperative computed tomography (CT) imaging with intraoperative passive navigation was used to perform 64 pedicle screw insertions in the thoracolumbar region. At the same time, 64 pedicle screw insertions were performed manually in the same region and on the same vertebral levels. Surgery was followed in all cases by postoperative radiographs and computed tomography examination, which allowed measurements of screw position relative to pedicle position to be performed. A comparison between the two groups showed that six screws in 64 vertebra (9%) had incorrect placement with the computer-assisted technique whereas 28 screws in 64 vertebra (44%) had incorrect placement with manual insertion. The intraoperative accuracy provided by the computer after registration was better than 1 mm. The good results obtained are similar to those reported in the literature. The cortex penetration observed with the computer-assisted technique was not imputed to computer failure. Errors by the surgeon in acquiring data in the pre- and perioperative steps may explain the six incorrect screw placements. This clinical experience confirms that the accuracy and the reliability of this computer-assisted technique are good.

Bone Screws↗
PubMed1992

A neuromuscular monitoring system based on a personal computer.

We have developed a computerized neuromuscular monitoring system (NMMS) using commercially available subsystems, i.e., computer equipment, clinical nerve stimulator, force transducer, and strip-chart recorder. This NMMS was developed for acquisition and analysis of data for research and teaching purposes. Computer analysis of the muscle response to stimulation allows graphic and numeric presentation of the twitch response and calculated ratios. Since the system can store and recall data, research data can be accessed for analysis and graphic presentation. An IBM PC/AT computer is used as the central controller and data processor. The computer controls timing of the nerve stimulator output, initiates data acquisition, and adjusts the paper speed of the strip chart recorder. The data processing functions include establishing control response values (when no neuromuscular blockade is present), displaying force versus time and calculated data graphically and numerically, and storing these data for further analysis. The general purpose nature of the computer and strip chart recording equipment allow modification of the system primarily by changes in software. For example, new patterns of nerve stimulation, such as the posttetanic count, can be programmed into the computer system along with appropriate data display and analysis routines. The NMMS has functioned well in the operating room environment. We have had no episodes of electrocautery interference with the computer functions. The automated features have enhanced the utility of the NMMS.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Systems↗
PubMed1988

Future in biomolecular computation.

Large-scale computations for biomolecules are dominated by three levels of theory: rigorous quantum mechanical calculations for molecules with up to about 30 atoms, semi-empirical quantum mechanical calculations for systems with up to several hundred atoms, and force-field molecular dynamics studies of biomacromolecules with 10,000 atoms and more including surrounding solvent molecules. It can be anticipated that increased computational power will allow the treatment of larger systems of ever growing complexity. Due to the scaling of the computational requirements with increasing number of atoms, the force-field approaches will benefit the most from increased computational power. On the other hand, progress in methodologies such as density functional theory will enable us to treat larger systems on a fully quantum mechanical level and a combination of molecular dynamics and quantum mechanics can be envisioned. One of the greatest challenges in biomolecular computation is the protein folding problem. It is unclear at this point, if an approach with current methodologies will lead to a satisfactory answer or if unconventional, new approaches will be necessary. In any event, due to the complexity of biomolecular systems, a hierarchy of approaches will have to be established and used in order to capture the wide ranges of length-scales and time-scales involved in biological processes. In terms of hardware development, speed and power of computers will increase while the price/performance ratio will become more and more favorable. Parallelism can be anticipated to become an integral architectural feature in a range of computers.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗
PubMed2001

Correlating computed tomography and positron emission tomography scan with operative findings in metastatic colorectal cancer.

INTRODUCTION: Several studies have been performed comparing computed tomography scan with positron emission tomography scan in clinical decision making. Unfortunately, therapeutic decisions are being made based on positron emission tomography scan data without a clear understanding of how well the diagnostic findings correlate with the clinical findings. METHODS: A retrospective review of 41 patients with metastatic colorectal cancer was performed. All patients had both a computed tomography scan and a positron emission tomography scan before surgical exploration. All underwent surgical re-exploration. Findings were divided into hepatic, extrahepatic, and pelvic regions of the abdomen. Computed tomography scan and positron emission tomography scan findings were either confirmed or refuted by the operative findings. RESULTS: Positron emission tomography scan was found to be more sensitive than computed tomography scan when compared with actual operative findings in the liver (100 vs. 69 percent, P = 0.004), extrahepatic region (90 vs. 52 percent, P = 0.015), and abdomen as a whole (87 vs. 61 percent, P < 0.001). Sensitivities of positron emission tomography scan and computed tomography scan were not significantly different in the pelvic region (87 vs. 61 percent, P = 0.091). In each case, specificity was not significantly different between the two examinations. CONCLUSION: Computed tomography scan and positron emission tomography scan are both diagnostic tests useful in the evaluation of metastatic colorectal cancer. However, positron emission tomography scanning is more sensitive than computed tomography scanning and more likely to give the correct result when actual metastatic disease is present.

Abdominal Neoplasms↗
PubMed1994

A client-computer interface for questionnaire data.

Our purpose was to assess efficiency and patient acceptance of a simple, inexpensive method of direct client-computer interface. A computerized version of the Sickness Impact Profile (SIP) was developed with the standard keyboard replaced by a numeric keypad. Forty-eight volunteer clients of an occupational rehabilitation center completed both the paper format and the computer format in randomized order, then were asked to compare the two methods in four areas. The majority of subjects rated the computer as easier to use and as the preferred method. Most subjects rated the computer and paper formats as equivalent in comfort and understanding. A summary score established that significantly more individuals preferred the computer format over the paper format (p = .02). Efficiency was determined by the mean time to score the test and produce a report (computer 39s, paper 309s). The correlation coefficients for the physical, psychosocial, and overall scores were very acceptable being greater than 0.90. These data indicate that a simple client-computer interface for the SIP is preferred by clients and is more efficient compared to the paper and pencil format.

Adult↗
PubMed2006

Low-dose computed tomography: a solution for in vivo medical imaging and accurate patient-specific 3D bone modeling?

BACKGROUND: The number of in vivo clinical biomedical experiments based on computed tomography is increasing. International radiation-protection bodies are promoting the use of low-dose computed tomography to reduce radiation absorption by the subject undergoing imaging. On the other hand no data exist in the literature to quantify whether or not low-dose computed tomography would lead to a decrease of result quality when used for three-dimensional bone modeling and related measurements. METHODS: This paper aimed at finding a consensus between minimal X-ray radiation of the subject, and satisfactory image data quality, especially for accurate three-dimensional bone modeling. Several standard computed tomography and low-dose computed tomography sequences were analyzed in three tests and statistically compared. FINDINGS: Absence of significant difference between standard and low-dose computed sequences indicated that the low-dose setting would not produce less accurate three-dimensional models, while it decreased the effective X-ray dose up to 90% compared to standard settings. INTERPRETATION: Low-dose computed tomography seems suitable for accurate three-dimensional bone modeling, while the related effective X-ray radiation is low. Such setting is therefore advised for any in vivo medical imaging aiming to collect bone data.

Bone and Bones↗
PubMed2005

Multidetector-row computed tomography vs. angiography and intravascular ultrasound for the evaluation of the diameter of proximal coronary arteries.

BACKGROUND: Multidetector-row computed tomography has evolved as a promising method for noninvasive visualization of coronary arteries and detection of coronary artery calcification. We determined the accuracy of computed tomography for measurement of coronary artery lumen diameters in comparison to quantitative coronary angiography and intravascular ultrasound (IVUS). METHODS: Eighteen patients (4 female, age 62+/-8 years) with known or suspected coronary artery disease were investigated by computer tomography (4x1 mm collimation, rotation time: 500 ms, table feed: 1.5 mm/rotation). Coronary angiography and IVUS were performed in the left anterior descending, left circumflex and right coronary artery according to common standards. Lumen diameters were measured at the origin of the coronary artery and 10, 30 and 50 mm distally. Results of all three techniques were compared. RESULTS: Only measuring points evaluated by all measuring techniques were included. Thus, 50 diameters could be analyzed. The correlation R between computed tomography and angiography measures was 0.909 (p<0.05) at the origin of the artery, 0.907 (p<0.05) at 10, 0.841 (p<0.05) at 30 and 0.780 (p<0.05) at 50 mm distally. The correlation R between computed tomography and IVUS was 0.934 at the origin (p<0.05), 0.867 at 10 (p<0.05), 0.880 at 30 (p<0.05) and 0.727 at 50 mm (p<0.05). CONCLUSIONS: Multidetector-row computed tomography is a promising tool to measure the proximal coronary artery diameters with a good correlation to angiographic and IVUS measurements. Multidetector-row computed tomography might become more feasible with improvement of technology, e.g. with 16 row scanners.

Coronary Angiography↗
PubMed2005

Computer technology in detection and staging of prostate carcinoma: a review.

After two decades of increasing interest and research activity, computer-assisted diagnostic approaches are reaching the stage where more routine deployment in clinical practice is becoming a possibility [Kruppinski, E.A., 2004. Computer-aided detection in clinical environment: Benefits and challenges for radiologists. Radiology 231, 7-9]. This is particularly the case in the analysis of mammographic images [Helvie, M.A., Hadjiiski, L., Makariou, E., Chan, H.P., Petrick, N., Sahiner, B., Lo, S.C., Freedman, M., Adler, D., Bailey, J., Blane, C., Hoff, D., Hunt, K., Joynt, L., Klein, K., Paramagul, C., Patterson, S.K., Roubidoux, M.A., 2004. Sensitivity of noncommercial computer-aided detection system for mammographic breast cancer detection: pilot clinical trial. Radiology 231, 208-214] and in the detection of pulmonary nodules [Reeves, A.P., Kostis, W.J., 2000. Computer-aided diagnosis for lung cancer. Radiol. Clin. North Am. 38, 497-509]. However, similar approaches can be applied more widely with the promise of increasing clinical utility in other areas. We review how computer-aided approaches may be applied in the diagnosis and staging of prostatic cancer. The current status of computer technology is reviewed, covering artificial neural networks for detection and staging, computerised biopsy simulation and computer-assisted analysis of ultrasound and magnetic resonance images.

Adenocarcinoma↗
PubMed2001

Environmental challenges in computer manufacturing.

The purpose of this research is to examine the environmental policies and programs that have been instituted by four large computer manufacturers. These environmental concerns, while not highly publicized, present an extremely important challenge to computer manufacturers, as well as to our society in general. Though the environmental programs of these computer manufacturers have been in place for several years, the topic of environmental health and safety (EHS) in computer manufacturing is still a relatively new one. Four major computer manufacturers that have instituted environmental programs are selected in this research. Their environmental policies and programs are examined in detail and compared with each other to show the relative strength and weakness. The result of this research highlights that with the amazing growth of computer use for both business and in our daily life, it will only be a matter of time before the issue -- the environmental challenges in computer manufacturing -- gains prominence and exposure in our society on a large-scale basis.

Computers↗
PubMed1998

Development in a Windows environment of a radiation treatment planning system for personal computers.

A new personal computer (PC) radiotherapy treatment planning system (RTPS) is presented. The PC-based RTPS is designed to run in the Microsoft Windows 3.11 environment (and later versions), for computers equipped with 486 or Pentium processors. The algorithm used by the new PC-based program for dose calculation belongs to the 'radiological pathlength' category and it was previously implemented on VAX 711 computers at Memorial Sloan-Kettering Cancer Center (MSKCC) in New York, NY, within EXTREP-III RTPS. The EXTREP-III program is a two-dimensional RTPS (with restricted three-dimensional capabilities), developed and used in clinical practice at MSKCC during the 1980s. The PC-based program is implemented in the Visual Basic (version 3.0) language and supports features commonly available in most photon-mode RTPSs: dose calculation for fixed, isocentric and rotational irradiation techniques, dose corrections for both internal inhomogeneities and external inhomogeneities (boluses and compensators), association of machine-specific beams with various wedges and blocks, etc. The graphic interface of the PC-based RTPS is completely new and is designed to meet the requirements of fast and accurate planning. The user interface consists of an event-oriented button-based console which allows users to perform planning and to have isodose charts overlaid on patient computed tomography images initially loaded in the program. The PC-based RTPS tests, performed in order to assess its accuracy and speed of computation, show good results. The acceptable computation times obtained, the good accuracy in dose computation and the user-friendly interface of the program are sufficient reasons to consider the PC-based RTPS a good quality-price ratio tool for radiation treatment planning in cancer therapy.

Algorithms↗
PubMed2002

Digital and biological computing in organizations.

Michael Conrad unveiled many of the fundamental characteristics of biological computing. Underlying the behavioral variability and the adaptability of biological systems are these characteristics, including the ability of biological information processing to exploit quantum features at the atomic level, the powerful 3-D pattern recognition capabilities of macromolecules, the computational efficiency, and the ability to support biological function. Among many other things, Conrad formalized and explicated the underlying principles of biological adaptability, characterized the differences between biological and digital computing in terms of a fundamental tradeoff between adaptability and programmability of information processing, and discussed the challenges of interfacing digital computers and human society. This paper is about the encounter of biological and digital computing. The focus is on the nature of the biological information processing infrastructure of organizations and how it can be extended effectively with digital computing. In order to achieve this goal effectively, however, we need to embed properly digital computing into the information processing aspects of human and social behavior and intelligence, which are fundamentally biological. Conrad's legacy provides a firm, strong, and inspiring foundation for this endeavor.

Adaptation, Physiological↗
PubMed1999

Improving breast cancer diagnosis with computer-aided diagnosis.

RATIONALE AND OBJECTIVES: The purpose of this study was to test whether computer-aided diagnosis (CAD) can improve radiologists' performance in breast cancer diagnosis. MATERIALS AND METHODS: The computer classification scheme used in this study estimates the likelihood of malignancy for clustered microcalcifications based on eight computer-extracted features obtained from standard-view mammograms. One hundred four histologically verified cases of microcalcifications (46 malignant, 58 benign) in a near-consecutive biopsy series were used in this study. Observer performance was measured on 10 radiologists who read the original standard- and magnification-view mammograms. The computer aid provided a percentage estimate of the likelihood of malignancy. Comparison was made between computer-aided performance and unaided (routine clinical) performance by using receiver operating characteristic (ROC) analysis and by comparing biopsy recommendations. RESULTS: The average ROC curve area (Az) increased from 0.61 without aid to 0.75 with the computer aid (P < .0001). On average, with the computer aid, each observer recommended 6.4 additional biopsies for cases with malignant lesions (P = .0006) and 6.0 fewer biopsies for cases with benign lesions (P = .003). This improvement corresponded to increases in sensitivity (from 73.5% to 87.4%), specificity (from 31.6% to 41.9%), and hypothetical positive biopsy yield (from 46% to 55%). CONCLUSION: CAD can be used to improve radiologists' performance in breast cancer diagnosis.

Area Under Curve↗
PubMed1999

2-D and 3-D reconstructions of spiral computed tomography in localization of the inferior alveolar canal for dental implants.

OBJECTIVE: The purpose of this study was to compare and validate the accuracy of measurements on 2-dimensional and 3-dimensional reconstructions from spiral computed tomography in localization of the inferior alveolar canal. STUDY DESIGN: Four edentulous human cadaver heads with intact mandibles were imaged in a spiral computed tomography scanner. The data were transferred to a networked computer workstation to generate 2-dimensional orthoradially reformatted and 3-dimensional volumetric images. Linear measurements of the images were made from the superior border of the inferior alveolar canal to the alveolar crest. The specimens were then dissected at corresponding locations, and physical measurements were made. RESULTS: There were no statistically significant differences between the 2-dimensional computed tomography measurements and the physical measurements or between the 3-dimensional computed tomography measurements and the physical measurements. However, we did find a statistically significant difference between the 2-dimensional and 3-dimensional computed tomography measurements. CONCLUSIONS: 2-dimensional and 3-dimensional computed tomography images allow accurate measurements for localization of the inferior alveolar canal.

Adult↗
PubMed2002

Learning preferences, computer attitudes, and student evaluation of computerised instruction.

OBJECTIVE: To explore the relationship between learning preferences, attitudes towards computers, and student evaluation of a computer-assisted instructional (CAI) program. CONTEXT: A third year required clerkship in surgery at the University of Nebraska Medical Center. METHODS: A mixed-methods design combining attitudinal measures and qualitative interviews was employed to assess student reactions to a CAI program on angiography completed during a required surgical clerkship. Between January 1998 and July 1999, 151 students completed the program. Prior to participating, students completed the Rezler Learning Preference Inventory (LPI) and a computer attitudes survey (CAS). The LPI characterizes learning preferences as being abstract or concrete, individual or interpersonal, and student-structured or teacher-structured. The CAS measures attitudes towards computers and their role in education. After using the CAI program, students evaluated the module by completing an 18 item questionnaire. Based on LPI and CAS scores, 31 students were invited to participate in an in-depth qualitative interview on their experiences and perceptions of the program. RESULTS: There was no relationship between learning preferences, computer attitudes, and evaluation of the CAI program. Students were very positive about the program's content, clarity, organization, and ease of use. They also rated it as efficient and effective. However, many still indicated a preference for lecture and text-based learning. Qualitative interviews suggest students worry computers will supplant student--teacher contact. CONCLUSIONS: Learning preferences and prior attitudes toward computers did not bias student reactions to the CAI program assessed in this study. However, students expressed concerns that CAI would interfere with the traditional student--teacher encounter and relationship.

Attitude to Computers↗
PubMed1998

A sticker-based model for DNA computation.

We introduce a new model of molecular computation that we call the sticker model. Like many previous proposals it makes use of DNA strands as the physical substrate in which information is represented and of separation by hybridization as a central mechanism. However, unlike previous models, the stickers model has a random access memory that requires no strand extension and uses no enzymes; also (at least in theory), its materials are reusable. The paper describes computation under the stickers model and discusses possible means for physically implementing each operation. Finally, we go on to propose a specific machine architecture for implementing the stickers model as a microprocessor-controlled parallel robotic workstation. In the course of this development a number of previous general concerns about molecular computation (Smith, 1996; Hartmanis, 1995; Linial et al., 1995) are addressed. First, it is clear that general-purpose algorithms can be implemented by DNA-based computers, potentially solving a wide class of search problems. Second, we find that there are challenging problems, for which only modest volumes of DNA should suffice. Third, we demonstrate that the formation and breaking of covalent bonds is not intrinsic to DNA-based computation. Fourth, we show that a single essential biotechnology, sequence-specific separation, suffices for constructing a general-purpose molecular computer. Concerns about errors in this separation operation and means to reduce them are addressed elsewhere (Karp et al., 1995; Roweis and Winfree, 1999). Despite these encouraging theoretical advances, we emphasize that substantial engineering challenges remain at almost all stages and that the ultimate success or failure of DNA computing will certainly depend on whether these challenges can be met in laboratory investigations.

Computer Simulation↗
PubMed2003

Acceptability and feasibility of a computer-tailored physical activity intervention using stages of change: project FAITH.

This study investigated the feasibility and acceptability of a new computer-tailored intervention promoting physical activity in a general population, and explored if there are differences in the reported feasibility and acceptability between stages of change, gender, age groups, education levels and familiarity with computer use. The computer-tailored intervention program consists of questionnaires concerning demographics, physical activity and psychosocial determinants, leading to a 'physical activity advice' and an 'action plan'. This feedback was constructed taking the stages of change into account, at content level as well as in the way participants were approached. One hundred and ninety-two participants, between 25 and 55 years of age, ran through the tailored materials, and completed an acceptability and feasibility questionnaire afterwards. This questionnaire contained feasibility and acceptability questions about all the intervention aspects: intervention questions, physical activity advice, action plan and computer use. High acceptability and feasibility scores were found for all intervention parts. Only a few significant differences in acceptability and feasibility scores between stages of change, gender, age groups, education levels and familiarity with computer use were found. These results suggest that this computer-tailored intervention is an acceptable and feasible tool for promoting physical activity for respondents having different stages of change, ages, gender, education levels and computer use.

Adult↗
PubMed2004

Do we need three-dimensional computed tomography in maxillofacial surgery?

In a retrospective clinical study (2000-2003), 121 patients' radiographs and computed tomography scans were reviewed to establish the clinical value of three-dimensional computed tomography. Eighty patients had computed tomography scans; 48 had three-dimensional computed tomography scans for diagnosing facial fractures, 3 for diagnosing temporomandibular joint ankylosis, 1 for tumor with bone destruction, and 1 for a mandibular cyst. It is concluded that axial, coronal, and three-dimensional computed tomography is of crucial importance and should be mandatory for all suspected comminuted and displaced midface fractures instead of plain radiographs. Three-dimensional computed tomography is also recommended for comminuted mandibular fractures and temporomandibular joint ankylosis. Three-dimensional computed tomography is not recommended for the diagnosis of minimally displaced fractures.

Facial Bones↗
PubMedDate not supplied

Web-based touch-screen computer assessment of chronic low back pain: a pilot study.

The objective of this study was to evaluate the acceptability and feasibility of a Web-based touch-screen computer questionnaire as a data collection method for patients experiencing chronic low back pain in a tertiary spine clinic. Participants completed the Oswestry Low Back Pain Disability Index, SF-36, and Beck Depression Inventory using a touch-screen computer. The time taken to complete the questionnaire was recorded electronically (M = 27.4 minutes; SD = 13.8). Prior computer experience and perceptions of computer use were also assessed. Low back pain was evaluated before and after completing the touch-screen computer questionnaire. Observations of sitting and standing tolerances were made. Participants completed a nine-item paper-and-pencil satisfaction survey after completing the computer questionnaire. Overall satisfaction level with this mode of data collection was high, supporting a larger study using touch-screen technology in patients with chronic low back pain. Important factors influencing satisfaction were the computer environment, ease of use, security, and the ability to interrupt the questionnaire process to allow for changes in sitting or standing posture.

Activities of Daily Living↗