Results Of A Six-State Pilot Study To Collect Exposure, Technique And Processing Data In Chest Radiography

Abstract

The routine measurement of exposures for a reference dimension patient in diagnostic radiology is regarded as an important part of an effective quality assurance program. The most frequent radiologic examination conducted in the United States is chest radiography. If manual techniques are used to conduct the exam, the procedure for measuring exposure to the reference patient is straight-forward. However, if automatic exposure controlled (AEC) techniques are used, a patient-equivalent chest phantom must be employed to reproducibly attenuate the x-ray beam. This is of particular importance if exposures are to be compared among AEC systems with different entrance x-ray spectra. Exposure monitoring is just part of the quality assurance story. Radiographic techniques, filtration, scatter reduction, film/screen use, and film processing performance (among other factors) must also be assessed, in order to effectively evaluate and modify these exposures so that they provide appropriate image quality. The first four factors are relatively easy to determine through measurement or documentation. Poor processor performance, potentially a major cause of abnormally high patient exposure, is more difficult to assess. We have designed, constructed and tested a Lucite/aluminum patient-equivalent attenuation chest phantom (LucAl) to use in the estimation of standard posteroanterior (22-23 cm) patient exposures for both manual and AEC chest systems. A sensitometric procedure that can be used to assess relative processor performance has also been developed. This paper describes these two procedures and their use in a six-State pilot study to monitor and evaluate exposure, technique and processor data in chest radiography. Results from approximately 200 chest systems will be summarized.