Distortion of bar phantom images as a result of two-dimensional sampling.
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Data Display↗
Biomedical subjects
D R Shearer
Publications and source records attributed to D R Shearer.
An improved indifferent electrode in surgical diathermy.
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Electrocoagulation↗
Temperature dependence of x-ray induced luminescence from medical x-ray screens.
Texts in diagnostic radiography give rules for adjustment of exposure parameters to compensate for the effect of temperature on the efficiency of film-screen combinations. These rules are appropriate for traditional phosphors, such as calcium tungstate (CaWO4) and lead barium sulfate (BaSO4:Pb) but may not be applicable to newer screens in current use such as those of the rare-earth type. The effect of temperature on x-ray induced luminescence from modern and traditional screens has been compared over a temperature range of approximately-130 to approximately 60 degrees C and has been found to differ markedly. Typically, the luminescent emission from rare-earth phosphors varies by less than 10% over this temperature range compared to the 60% change in efficiency for conventional screens over the same temperature range. One type of modern screen, however, shows a continuous decrease in luminescent efficiency as the temperature is lowered. Qualitative physical explanations for these effects are presented.
Luminescent Measurements↗
Call a medical physicist: a guide to troubleshooting.
A catastrophic problem may occur when an imaging system suddenly fails. In most cases, however, a problem comes on gradually until the imaging quality is so far degraded it becomes clinically unacceptable. In that circumstance, pressure is put on the technologist to do something quickly to improve the quality of the images. There are several guidelines to follow when a similar situation occurs in your workplace. First, any correction should be made rationally using the data at hand. Don't rush to change a lot of things all at once or you'll never know what did work. Putting in a call to a physicist may be in your best interest as the second step to follow. A qualified diagnostic medical physicist has an overview of the principals and applied technology of the imaging process. Both the radiologic technologist and the technical representative from film or x-ray and film processor companies have training in all areas of x-ray technology. It is the physicists' many years of training in the application of scientific methods to medical imaging problems that provide an edge in diagnosing technical problems. Their strength is that they are good with scientific concepts and numbers. Don't let the physicist leave until the problem has been shown to be solved. Bring in the service engineer to run a control strip to show that the remedy has indeed had the desired effect with no undesirable side-effects. Document the problem and the solution is the fourth rule, while rule five is to use the physicist to coordinate the process, objectively measure and assess the results of any change. You'll be back on line more quickly and will know what went wrong.
Diagnostic Imaging↗
Fear of a white hat.
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Cost-Benefit Analysis↗