Reduction of personnel exposure in diagnostic radiology.
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Film Dosimetry↗
Biomedical subjects
W K Chu
Publications and source records attributed to W K Chu.
Fourier analysis of the echocardiogram.
Fourier analysis has been applied to the analysis of echocardiograms, with the result that anterior mitral leaflet waveforms have been classified in a manner which is unambiguous and which lends itself easily to present-day automated technology.
Echocardiography↗
Toward the automation of echocardiography.
Schemes applicable to the automated classification of disease states identifiable through echocardiography are being studied. Initial success has been achieved in the classification of anterior mitral leaflet wave forms associated with mitral stenosis and mitral valve prolapse. These two categories were found to be readily distinguished from the normal state in a Fourier analysis framework.
Automation↗
A computerized radiation safety system.
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Computers↗
Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: I. Whole plant study.
Glasshouse experiments were conducted to determine the accumulation, distribution and transformation of o,p'-DDT, p,p'-DDT and PCBs by common reed (Phragmites australis) and rice (Oryza sativa L.) under hydroponic conditions. The culture solution was spiked with the organic pollutants and samples were collected daily. Analysis of the plants at harvest showed that both species had removed DDT and PCBs from the solution. DDT appeared to have accumulated within P. australis by both passive adsorption and active absorption. Both o,p'-DDT and p,p'-DDT were transformed within P. australis. DDD was the major metabolite and the transformation was mediated by reductive dehalogenation. Plant long-distance transportation systems may be involved in the translocation of PCBs within P. australis and the affinity of the PCBs for lipids is one of the major factors affecting their uptake and translocation within the plants. Similar but less pronounced results were found in O. sativa and suggest that these wetland plants may be used for the plant-mediated remediation of persistent organic pollutants.
Biotransformation↗
Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: II. Enzyme study.
Two wetland plant species, Phragmites australis and Oryza sativa, were grown in a glasshouse under hydroponics conditions. Enzyme extracts from different parts of the plants were used to determine the transformation rate of o,p'-DDT, p,p'-DDT and PCBs. The organic pollutants were directly spiked into the enzyme extracts, and samples were collected every 30 min and analyzed with a GC-ECD. Root extracts of P. australis readily degraded and transformed DDT and some PCB congeners with a low degree of chlorination. In contrast, crude extracts of O. sativa showed no appreciable degradation or transformation of DDT or PCBs. Inhibition studies indicated that the degradation and transformation of both DDT and PCBs by P. australis enzymes were partly mediated by peroxidase and the plant P-450 system. PCBs with a high degree of chlorination were highly resistant to transformation or degradation by plant enzymes. Both wetland plant species accumulated substantial quantities of the persistent organic chemicals but had different degradation capacities. The enzyme systems in P. australis were much more effective that those in rice in the degradation and transformation of the organic pollutants.
Biotransformation↗
Comprehensive radiological equipment management program.
The increasing cost and complexity of state-of-the-art radiological equipment, and the need for more comprehensive safety and performance assurance, have increased maintenance expenditures to a level where they have become one of the largest operating expenses of radiology departments. To cope with this ever increasing expenditure, a comprehensive in-house maintenance program was implemented in our institution. This program properly balanced the capability of the radiology department's in-house technical personnel with support provided by equipment manufacturers' service organizations. Quality assurance activities are also included as an integral part of the entire program. Since the implementation of the program, an average 40% reduction in the annual maintenance expenditure has been observed.
Hospital Bed Capacity, 300 to 499↗
Echocardiogram analysis in a pattern recognition framework.
Echocardiogram analysis is treated in a pattern recognition framework. Anterior mitral leaflet waveforms are classified for the four-class problem consisting of the classes "normal," "mitral stenosis," "mitral valve prolapse," and "idiopathic hypertrophic subaortic stenosis." In addition, aortic root waveforms and left ventricular wall waveforms are classified for the two-class problem consisting of the classes "normal" and "idiopathic hypertrophic subaortic stenosis." One common method of analysis (Fourier analysis) underlies each classification scheme. Classification accuracy is sufficiently good to warrant the inference that successful automated decision-making based on the algorithms investigated is feasible.
Aortic Valve↗
CT scanograms compared with conventional orthoroentgenograms in long bone measurement.
In this article the standard orthoroentgenograph is compared with computed tomography (CT) scanography in determining bone length discrepancies. Dried femur bones are studied by both methods. The CT scanogram method is found to be more accurate than the orthoroentgenography method.
Femur↗
Potential impacts of MRI accidents.
A minor accident occurred in our Magnetic Resonance imaging suite. It is minor, because no personal injury nor equipment damage resulted from it. However, this incident has prompted us to review and re-emphasize our safety precautions and to investigate means of insurance coverage for any potential effects that could result from such incidents.
Accidents↗
CT measurements of cranial growth: alternative measurement method.
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Adolescent↗
A system for checking radiation therapy calculations for treatment time or monitor setting.
Errors in the calculation of radiation therapy treatment time or monitor setting are likely to occur with regularity unless adequate quality control procedures are utilized. These errors can be greatly reduced if appropriate computer systems are employed with programs which utilize analytical representations of dosimetric quantities. A system wherein dosimetry technologists routinely check treatment calculations using a computer terminal has been in operation in our department for several years and has proved helpful in uncovering calculation errors.
Computers↗
Routine skin dose calculation using a desk-top calculator.
A program that calculates the patient skin dose was developed using a programmable desk-top calculator (Hewlett-Packard HP-97). The calculation scheme is based upon the technique factors used for the radiographic examination and the radiation output characteristics of the x-ray generating devices. Thermoluminescent dosimetry (TLD) was used on some clinical examinations and phantoms to establish the validity of this program. The average percentage difference between the TLD results and the calculated values is less than 15 per cent. The program listing is available from the author upon request.
Computers↗