Dosis-Monitoring als Qualitätssicherungsinstrument in der digitalen Radiographie

PURPOSE: Automatic image processing procedures ensure a constant image quality. Overexposed images constitute a danger zone on account of a subjectively better image appearance (improved signal-to-noise ratio). We have examined the software "Dose-Monitoring" both for the identification of false exposures and as a quality control tool. MATERIALS AND METHODS: Firstly the correlation between dose and present IgM (mean grey tone from the crude histogram of a 12-bit image) was examined by exposing phantoms. A further-reaching comparison of the present IgM values of some MTRAs with the department average (nominal IgM) should detect tendencies for over- and underexposure. Finally a dose reduction in 12 forms of X-ray examination was evaluated with regard to IgM course controls (median IgM). RESULTS: A high correlation (0.987) between dose and mean grey tone (IgM). In some MRTAs tendency for over-/underexposure was detected. The dose reduction of defined types of X-ray examination lead to a trend to lower mean IgM values. DISCUSSION: Numerous factors have an influence on the IgM value thus making its evaluation difficult, even so it is a suitable parameter for uncovering tendencies to incorrect exposure and for identifying processes requiring optimization. CONCLUSIONS: The value of this tool lies in the quality assurance of dose fluctuations and a possible dose reduction.