J G Stears

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OBJECTIVE The purpose of this study was to measure radiation exposure levels in children undergoing cardiac catheterization. This information was used to assess methods of reducing exposure and to characterize total exposures. SUBJECTS AND METHODS The radiation exposure area product was determined for a total of 175 patients during three study intervals(More)
Shaped filters that are constructed of lead-loaded acrylic material for use in patient radiography are discussed. Use of the filters will result in improved overall image quality with significant exposure reduction to the patient (approximately a 2X reduction in breast exposure and a 3X reduction in thyroid gland exposure). Detailed drawings of the shaped(More)
OBJECTIVE A new asymmetric screen-film combination for conventional chest radiography was evaluated by four thoracic radiologists. MATERIALS AND METHODS Fifty chest radiographs obtained with a new asymmetric screen-film combination were compared with radiographs obtained in the same patients during the same breath-hold with a conventional system. Patients(More)
The posteroanterior projection was studied to determine if it could be a substitute for the commonly used anteroposterior projection as a method of reducing x-ray exposure to specific radiosensitive organs during intracranial tomography and scoliosis radiography. The use of the posteroanterior projection resulted in a reduction of 95% in exposure to the(More)
The authors compared asymmetric and conventional screen-film systems for chest radiography. The new imaging system, with asymmetric construction of the screens and film, has image quality characteristics substantially different from those of available screen-film combinations. This asymmetric screen-film system consists of a thin (high-resolution) front(More)
The half-value layer (HVL) of an x-ray beam is generally believed to increase with x-ray tube use. This increase in HVL has previously been attributed to the hardening of the x-ray beam as a result of a buildup of tungsten on the x-ray tube glass window. Radiographs and HVL measurements were obtained to determine the effect of tungsten deposited on the(More)
Noninvasive monitoring of x-ray output waveforms during acceptance testing, quality of control, and troubleshooting is beneficial in an ongoing radiographic quality assurance program. The intent of waveform monitoring is to watch for abnormalities that provide additional information about the condition of the x-ray system. Because waveform monitoring is(More)