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I present a BASIC language computer program that can be used on a variety of home computers to calculate intraocular lens powers and print this information on a report that can be included with hospital or office records and easily read in the operating room.
The proper evaluation of the accuracy of a new computer program for radiation-therapy dosimetry requires consideration of both the mathematical algorithm used in the program and the performance required in clinical applications. As an example, our evaluation of the irregular-fields dosimetry program currently marketed by SHM for their Rad-8 system is described. The evaluation begins with an explanation of the mathematical computation described. The evaluation begins with an explanation of the mathematical computation method, with emphasis on the points where the calculation differs from previous methods. Next, the procedure for setting up the beam data file is discussed. Finally, a step-by-step procedure is described in which calculated doses are compared with measured doses, using a Varian Clinac-4 with lead flattening filter, and the limits within which a +/- 5% accuracy is attainable are estimated. Some sources of error and areas for possible improvements are mentioned.
To allow an exchange of measurements and criteria between different electrocardiographic (ECG) computer programs, an international cooperative project has been initiated aimed at standardization of computer-derived ECG measurements. To this end an ECG reference library of 250 ECGs with selected abnormalities was established and a comprehensive reviewing scheme was devised for the visual determination of the onsets and offsets of P, QRS, and T waves. This task was performed by a group of cardiologists on highly amplified, selected complexes from the library of ECGs. With use of a modified Delphi approach, individual outlying point estimates were eliminated in four successive rounds. In this way final referee estimates were obtained that proved to be highly reproducible and precise. This reference data base was used to study measurement results obtained with nine vectorcardiographic and 10 standard 12-lead ECG analysis programs. The medians of program determinations of P, QRS, and T wave onsets and offsets were close to the final referee estimates. However, an important variability could be demonstrated between measurements from individual programs and mean differences from the referee estimates amounted to 10 msec for QRS for certain programs. In addition, the variances of all programs with respect to the referee point estimates were variable. Some programs proved to be more accurate and stable when the data from high- vs low-noise recordings were analyzed. Average Q wave durations calculated from ECGs for which programs agreed on the presence of a Q or QS wave differed by more than 8 msec in several program-to-program comparisons. Such differences may have important consequences with respect to diagnostic performance. Various factors that might explain these differences have been determined. The present study demonstrates that to allow an exchange of results and diagnostic criteria between different ECG computer programs, definitions, minimum wave requirements, and measurement procedures urgently need to be standardized.
This paper describes a computer program that can find tRNA genes within long DNA sequences. The program obviates the need to map the tRNA genes.
Analysts must deal frequently with missing data in multivariate analysis. In such cases, estimating the covariance maxtrix V of the dependent variables usually involves initial estimation and iterative adjustment of imputed missing data values, and/or smoothing of an estimate V which is not necessarily positive semi-definite. This paper presents an alternative procedure for computing estimates of relevant multivariate parameters in situations where missing data occur at random and with small probability. MISCAT is a computer program which computes multivariate ratio estimates of the means and a corresponding positive semi-definite estimate of the covariance matrix. It is an extension of GENCAT, which is a program for the generalizaed least squares analysis of categorical data. Thus, one advantage of dealing with missing data in this manner is that variation among the ratio estimates may be conveniently analyzed within MISCAT using asymptotic regression methodology, provided that sample sizes are sufficiently large. An example is given to illustrate such analysis for longitudinal data from a multicenter clinical trial.
A FORTRAN computer program was developed to calculate recombination values from F2 data. The input to the program is data on codominant alleles in any number of F2 families segregating for any number of loci, the limit being applied by the computer's memory capacity. For each pair of loci, regardless of the number of segregating progenies used, one recombination value is estimated by the method of maximum likelihood and reported with its standard error. In cases in which more than one family is used for the estimation, the chi-square for the homogeneity of the data also is reported.
Presented is a computer program designed to convert any given set of exposure factors sequentially into another, yielding either an equivalent photographic density or one increased or decreased by a specifiable proportion. In addition to containing the wherewithal with which to manipulate a set of exposure factors, the facility to print hard (paper) copy is included enabling the results to be pasted into a notebook and used at any time. This program was originally written as an investigative exercise into examining the potential use of computers for practical radiographic purposes as conventionally encountered. At the same time, its possible use as an educational tool was borne in mind. To these ends, the current version of this program may be used as a means whereby exposure factors used in a diagnostic department may be altered to suit a particular requirement or may be used in the school as a mathematical model to describe the behaviour of exposure factors under manipulation without patient exposure.
A computer program has been written which performs a stepwise selection of variables for logistic regression using maximum likelihood estimation. The selection procedure is based on likelihood ratio tests for the coefficients. These tests are used in a forward selection and a backward elimination at each step. The use of the program is illustrated by several examples.
A test library composed of the ECG's of 228 patients with clinically proven myocardial infarction and 294 subjects without clinical evidence of infarction was used to assess the performance of three visual coding procedures and three computer programs designed to classify ECGs according to the Minnesota Code. The results showed that visual coding performed by one experienced senior coder tended to be more consistent than visual coding relying on two less experienced coders and arbitration of disagreements by a supervisor. There was no significant difference in coding results when only one preprocessed complex was coded in comparison with the more elaborate coding of the whole source ECG using majority rule. The coding performance of the three computer programs was similar to that of the visual coding procedures. It is concluded that computer coding of ECGs according to the Minnesota Code is feasible. Combined optimal use of automated coding and visual verification of selected items may still further improve coding precision. However, when judged against an ECG independent standard, the accuracy of all coding procedures in discriminating infarcts from non-infarcts according to the Minnesota code criteria is rather limited. 'Soft' criteria give a reasonable sensitivity with low specificity whereas the use of 'hard' criteria with adequate specificity results in a substantial drop in sensitivity.
The computer program INDEP-SELECT has been developed for selection of an optimal subset from a set of possibly informative diagnostic or prognostic variables. But the program is equally useful for other discriminant analysis or pattern recognition problems involving variable selection. The approach is probabilistic; i.e., diagnostic probabilities are assigned to a patient on the basis of the values observed on the diagnostic variables. The statistical model used is largely based on the assumption of independency between the variables, but one model-parameter, the so-called 'global association factor', is added in order to take dependency into account. The stepwise forward selection strategy of adding in each selection step a new variable to the set of already selected variables, is used. The user may choose between a number of selection criteria. Such a criterion is used in order to decide in each selection step which variable should be added. All criteria are based on measures of diagnostic or prognostic performance. INDEP-SELECT is able to handle a large number of variables, also with missing data, and a large number of patients. The program is written in ANS Standard FORTRAN, and takes relatively little computation time.
A quick and efficient computer program was developed in order to resolve the peaks from the thermoluminescence (TL) glow curve. The program was designed to be easily used on any MS Windows-based computer with a graphical user interface. In this program, a new method based on the general one-trap TL equation was adopted to analyse the TL glow curve with the traditional first-order, second-order and general-order kinetics model. The method described here, general approximation, generates TL glow peaks and interpolates the relevant TL parameters from the glow data. The program was tested with simulated and experimental TL glow data and the results were found to be adequate and reliable.
The use of the Baumgartner perfusion system allows the morphometric quantification of platelets interacting with vessel wall, however it presents the basic difficulties of morphometrical measurements. In order to facilitate the procedure of evaluation we developed a semiautomated method to avoid the complexity of the classical evaluation. Our system consists on an optical picture analysis system connected with a specially developed computer program which allows fast quantification. Simultaneously to the outlining of interacting platelets the computer program recognizes, corrects, selects and stores the information, in order to perform the final calculations as previously established. This system has been demonstrated to be as effective as the classical morphometric evaluation in the measure of platelets interacting with subendothelium. Potential sources of error such as subjectivity of the observers in selecting the class of interacting platelets are avoided. The use of this combined method opens the possibility to adapt the Baumgartner perfusion system to clinical routine and to the screening of drugs that modify platelet adherence.
A pocket computer program is described which allows rapid nutritional evaluation of hospitalized patients. Entries of anthropometric and laboratory measurements, along with the results of anergy testing allows display of the patient's nutritional assessment with degrees of depletion. Use of the program provides the clinician information which is of benefit to patient nutritional management and evaluation of significant risk potentials.
The American Animal Hospital Association Computer Program should benefit all small animal practitioners. Through the availability of well-researched and well-developed certified software, veterinarians will have increased confidence in their purchase decisions. With the expansion of computer applications to improve practice management efficiency, veterinary computer systems will further justify their initial expense. The development of the Association's veterinary computer network will provide a variety of important services to the profession.
The United States Environmental Protection Agency has published three computer programs, COMPLY, AIRDOS-PC, and CAP88-PC, to assist the regulated community in determining compliance with the Environmental Protection Agency radionuclide air emission standards. The programs calculate radiation doses from routine airborne release to the general public residing outside a nuclear facility site. They consider doses from inhalation, ingestion of contaminated food, air immersion, and ground deposition. A PC-based computer code, XOQDOQ-82, developed for the Nuclear Regulatory Commission, was also chosen to compare and evaluate dispersion results from the Environmental Protection Agency codes for the University of Missouri Research Reactor Center. Effects of building parameters, terrain conditions, and downwind distances on dispersion factors were calculated. The results of this study indicated that dispersion factors calculated using AIRDOS-PC and CAP88-PC were several times lower than those calculated using XOQDOQ-82 at all distances, and those dispersion factors calculated using COMPLY were several times lower than the XOQDOQ-82 values at distances greater than 600 m.
EPIGRAM is a computer program designed to improve access to State-level underlying cause mortality data. The program produces results for population, deaths, death rate, age-adjusted death rate, years of potential life lost (YPLL), YPLL rate, and confidence intervals. Results can be compared variously among age groups, counties, causes of death, races, regions, and years. The program's menu-driven interface facilitates the selection or modification of analysis parameters. Current selections are retained so the user can modify one parameter at a time. Based on the parameters that the user selects, the program produces a series of tables, one for each instance of a particular parameter. Each output table has columns for male, female, and both sexes combined, and an indefinite number of user-defined rows for age groups, causes of death, counties, races, regions, or years. EPIGRAM has major advantages over other methods for analyzing mortality and population data. The program uses relatively small amounts of memory and disk space, executes rapidly, is flexible, can be used by inexperienced computer users, provides online help screens and tutorials, and runs under DOS or UNIX without modification. The program currently is used to analyze mortality and population data for Texas. Although it is not currently available for distribution, support is being sought for its evaluation and possible implementation in State health departments to analyze data for other States, or other data sets, such as hospital discharge data or cancer incidence data.
The possibilities for reducing in Van de Geijn's computer program the original limitations for the size and the position within the field of shielding blocks are explored. New methods are presented which are based on experimental measurements as well as more theoretical approaches, without need for any change in the program itself. Two typical clinical examples are presented and the precision obtained critically investigated.
A computer program has been developed to aid in the brachytherapy of cancer of the cervix. Using a least-squares minimization algorithm, the program will optimize the source loading in intracavitary applicators so as to reproduce, as nearly as physical considerations allow, the dose distribution requested by the user. Applicator geometry and the relative positions of anatomical points of interest must be supplied to the program, as well as an inventory of available source strengths. Output from the computer includes the optimized source loading, time of application, and the resulting relative doses to the various user-selected points of interest.