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These same loading factors are recorded, along with the image receptor identification, and are used with the test tool in all future tests to evaluate the performance of the x-ray imaging system on a periodic basis. Weekly monitoring is recommended (minimum monthly) or each time the imaging equipment performance is uncertain. If the density of the attenuator image falls outside the density step range labelled -2 to +2, indicating a trend away from the previously established norm, significant deterioration in image quality has occurred and corrective action is required. Initially, since it has been established that image quality is a function of x-ray machine output and film processing variables, corrective action will be in the form of careful checks on physical parameters such as the source to film distance, loading factors, development time and temperature. Subsequent action to re-establish the desired image quality may require some technical assistance.
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