Computer programs in biomedicine最新文献

A computer program was developed for the Monte Carlo simulation of photon transport. The program was designed for photon transport simulation in geometries occurring in diagnostic radiology and especially for the investigation of scattered radiation. A method is described for the analogue sampling of scattering angle in coherent and incoherent scattering processes. The two scattering processes are treated separately, and the influence of coherent scattering, an often neglected process, can be estimated quantitatively. The program can also be used for the calculation of the energy imparted to water slabs and fluorescent screens.

A software package is described to reconstruct three-dimensional pictures in true perspective from a series of parallel sections using a low-cost computer system (Apple II plus). Data sampling via a graphic tablet and graphical output on the monitor screen or a digital plotter are assigned to different programs under control of a menu program. The number of data representing the object under study is unlimited. Originally written in BASIC, the programs were translated to machine language. As an application of the package, reconstructions of an identified large interneuron of the locust brain are presented.

We recorded discharge frequencies of 32 intrapulmonary chemoreceptors (IPC) during caudocranial and craniocaudal ventilation in the perfused duck lung. Blood gases, ventilatory gas flow, inspired P_CO2 and P_O2, and expired P_CO2 measured simultaneously were used to predict regional CO₂ and O₂ gradients within the lung. Gas exchange was modelled in 7 log normal ventilation-perfusion compartments using mass balance differentials with an adjustable step size. CO₂ and O₂ interactions during exchange were modelled using the Bohr effect. P₅₀, blood acid-base status and the CO₂ dissociation relationship. Close agreement (± 1.0 Torr) between simulated arterial and expired P_CO2 and observed values was achieved after forcing simulated Pa_O2 to converge on observed Pa_O2 by an iterative adjustment of the perfusive shunt or the log standard deviation of the ventilation-perfusion distribution. Using the IPC static CO₂ sensitivity measured in the non-perfused lung and the CO₂ gradients generated by the model, we have found evidence for a distributed multi-ending receptor system in the duck lung.

A microprocessor-based system is developed to measure and analyse flow-volume curves produced from forced expiratory manoeuvres. The system evaluates the slope-ratio parameter and displays it as a scaled plot against fractions of vital capacity together with a scaled plot of the flow-volume curves on a graphic display. Other conventional parameters and their predicted values are also calculated. Freedom is allowed for the operator to select or reject manoeuvres from several runs. The system is easily run and guided even by an operator with no programming knowledge.

This paper describes the digital signal processing work of a research project for studying children's cognitive processes by analyzing EEG signals during school-related tasks. The EEG being analyzed involves two homologous channels (left and right parietal area), and is recorded on magnetic tapes. The objective of the analysis is to determine if, by examining the alpha band of the ongoing EEG, different school tasks and correct vs incorrect responses can be detected. Analysis of alpha-band calls for the determination of signal power in the 7–12 Hz frequency band (adjusted for the age of the subjects) for each channel as well as correlation between the channels. A digital signal processing scheme implemented on an Apple II microcomputer was developed for such an analysis. The results obtained are discussed.

A computer program which enables detection of segmental abnormalities of the left ventricular contraction was developed using the principles of Leighton et al. [Circulation 50 (1974) 121–127]. A film projector, a digitizer a graphic display and a mini-computer are used. The end-diastolic (ED) and end-systolic (ES) left ventricular silhouettes are traced from 30° right anterior oblique cineangiograms projected on a screen of the film projector. The program determines semi-automatically both apexes and longitudinal axes of the left ventricle. Lines [(N − 1) ≤ 60] are drawn perpendicular to longitudinal axes, dividing longitudinal axes into equal N segments, respectively. These perpendicular lines are extended to intersect ED and ES silhouettes at 2(N − 1) points, respectively. The distances along each of 2(N − 1) hemiaxes are defined as short axes [S-EDi and S-ESi, i = 1 ∼ 2(N − 1)]. Segmental wall contractions are expressed as a percentage of the distance from S-EDi to S-EDi, and displayed as a graph with normal values (mean ± 2 SD). The presence and extent of segmental contraction abnormalities can be evaluated quantitatively by observing a percentage of segmental wall contractions. This program greatly facilitates a correct diagnosis in clinical use.

For bioequivalence testing of pharmaceutical formulations of the same drug entity, it is not sufficient to carry out an analysis of variance on the characteristic to be evaluated (e.g., area under the plasma level vs time curve, half-life of elimination, time to plasma-peak level, plasma peak level) and to establish ‘classical’ 95% confidence intervals for the difference or the ratio of the characteristic concerned. In the past 10 years, several approaches have been proposed as an aid in decision-making: Westlake's 95% intervals, Rodda and Davis' probabilities, Fluehler's posterior probability histograms and the evaluation of the residual variation coefficient. A survey of these approaches is given, together with a discussion of their merits, their differences and their similarities. It is recommended that the final evaluation should be supported by probability density plots, which facilitate easy understanding of the differences and similarities between the various approaches. A bioequivalence study with two types of oral tablets containing bepridil, a new anti-anginal drug, is used as an example. Computer programs are presented, which enable the user to easily apply the various approaches in order to meet requirements of regulatory agencies.

A FORTRAN computer program, running on a Digital PDP 11–34 minicomputer, has been developed for use in conjunction with a Cambridge Quantimet 720 image analyzer for the investigation of metaphase preparations in routine cytogenetics. During a short initiation phase the program is adapted to the type of metaphase being analyzed. The program is fast and its performance is good, even at low microscopic magnifications. It has other uses in biology for all investigations and characterizations of groups of small distinct elements widely spread within a preparation (e.g., autoradiography, bacteriology).