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Biomedical subjects

B M Moores

Publications and source records attributed to B M Moores.

At least 19 recordsLinked to original sources
PubMed1988

Image processing of digital chest ionograms.

A number of image-processing techniques have been applied to a digital ionographic chest image in order to evaluate their possible effects on this type of image. In order to quantify any effect, a simulated lesion was superimposed on the image at a variety of locations representing different types of structural detail. Visualization of these lesions was evaluated by a number of observers both pre- and post-processing operations. The operations employed included grey-scale transformations, histogram operations, edge-enhancement and smoothing functions. The resulting effects of these operations on the visualization of the simulated lesions are discussed.

Humans↗
PubMed1987

An investigation into the levels of radiation exposure in diagnostic examinations involving fluoroscopy.

In order to investigate the levels of radiation exposure resulting from fluoroscopic examinations, area-exposure product measurements were performed on 6532 patients whilst undergoing a variety of examinations at a large district general hospital. Results for both the same and different types of examinations, performed in two different X-ray rooms by a number of different radiologists, are compared in order to highlight some of the factors which influence the wide variations in patient exposure which frequently occur in radiological examinations. Variations in exposure of patients of different weights are also presented.

Body Weight↗
PubMed1986

Contrast-detail assessment of computed tomography scanners.

The design and construction of contrast-detail detectability phantoms for the assessment of the imaging performance of CT scanners are described. These phantoms have been employed to undertake a series of measurements on a number of different machines. The results are expressed in terms of object contrast which is consistent with the conventional definition of radiological contrast. For one particular scanner, the imaging performance of a number of image reconstruction and post-processing filters has been investigated. The results indicate that there was no observed energy dependence of contrast-detail detectability once differences in technique factors and attenuation were taken into account. A similar conclusion was drawn from the results of a set of measurements made to examine the effect on detectability of additional filtration.

Evaluation Studies as Topic↗
PubMed1985

A prototype digital ionographic imaging system.

A prototype digital ionographic imaging system is described. The process involves direct electrical reading of a latent electrostatic image which has been produced by an ionographic technique. The main design features of the system are outlined and their effect on its imaging performance highlighted. A preliminary assessment of the performance of the system in terms of resolution, noise, contrast and sensitivity is presented and compared with that of a conventional screen-film combination.

Analog-Digital Conversion↗
PubMed1985

Noise transfer in screen-film subtraction radiography.

The transfer of noise through the stages of a screen-film subtraction process was investigated. In particular the effect of measuring aperture size and film density on the measured noise granularity was studied. The relative contributions of quantum noise and film grain noise were found to depend on both aperture and density. Noise measurements are presented for a medium speed screen-film combination and also for a low noise alpha 16-Kodak Industrex C system. The effect of grain mottle and film blur on noise transfer through the multiple print process employed in subtraction radiography is demonstrated.

Humans↗
PubMed1984

Analysis of x-ray computed tomography images using the noise power spectrum and autocorrelation function.

A discrete representation of the reconstruction process, consistent with the method of data collection, has been used to derive expressions for the noise power spectrum, autocorrelation function and noise equivalent quanta (NEQ) of a computed tomography (CT) image. These parameters have been expressed in terms of basic scanning factors such as tube current, exposure time, slice width and number of detectors. Each of these factors affects the overall magnitude of the noise power spectrum, but the spatial frequency dependence is also determined by the type of reconstruction filter used in the computer algorithm. The noise power spectrum has been calculated for scanners employing either a ramp or Hanning weighted ramp filter. Predictions made from this theoretical analysis have been compared with experimental measurements made on various CT scanners. Measurements were made of the modulation transfer function (MTF) by techniques which permitted us to deduce the contributions of the algorithmic and non-algorithmic components to the overall MTF. NEQ values have been calculated for a number of CT scanners.

Humans↗
PubMed1984

Noise and contrast detection in computed tomography images.

A discrete representation of the reconstruction process is used in an analysis of noise in computed tomography (CT) images. This model is consistent with the method of data collection in actual machines. An expression is derived which predicts the variance on the measured linear attenuation coefficient of a single pixel in an image. The dependence of the variance on various CT scanner design parameters such as pixel size, slice width, scan time, number of detectors, etc., is then described. The variation of noise with sampling area is theoretically explained. These predictions are in good agreement with a set of experimental measurements made on a range of CT scanners. The equivalent sampling aperture of the CT process is determined and the effect of the reconstruction filter on the variance of the linear attenuation coefficient is also noted, in particular, the choice and its consequences for reconstructed images and noise behaviour. The theory has been extended to include contrast detail behaviour, and these predictions compare favourably with experimental measurements. The theory predicts that image smoothing will have little effect on the contrast-detail detectability behaviour of reconstructed images.

Humans↗
PubMed1982

An assessment of the radiation dose received by staff using fluoroscopic equipment.

Measurements of scattered radiation were made on two fluoroscopic installations, one with an overcouch tube and one with an undercouch tube. The annual doses to staff involved in a fluoroscopic procedure undertaken on both types of unit were estimated using measured dose rates and weighting factors referred to in ICRP 26. Environmental monitoring at the protective barrier was performed for various room layouts to determine the effect of both equipment and room design on the annual dose received by staff at the control panel. In all circumstances the annual dose to staff inside the control cubicle was negligible.

Environmental Exposure↗
PubMed1981

A suggested theory of the conventional tomographic imaging process.

An attempt is made to re-examine the well established theoretical basis of conventional tomography in the light of more detailed techniques being applied elsewhere in image analysis. Transfer function theory has been used to quantify the amount of edge detail reproduced by this process and the information in a tomogram is investigated in terms of edge detail associated with well resolved (unblurred) detail and also that associated with particular anatomical layers within the tomographed object, the theory has been used to define a cut plane thickness. A variety of different tube movements have been considered and calculated values of cut plane thickness are compared with those predicted by a simple geometric model. Besides the blurring associated with the tube movement the effect of x-ray focal spot, film-screen combination and also visual response of the observer have been included and their importance in the definition of cut plane thickness highlighted. One advantage of this approach appears to be the facility to quantify the performance of different tomographic tube movements and highlight the role of tomographic detail reproduced from body sections well removed from the cut plane.

Humans↗