[Influence of interest region and interest value settings on exposure index-analysis using chest clinical images].

With the digitization of general radiography, there are some concerns about an increase in radiation exposure doses. Therefore, the exposure index (EI) as a new dose index was proposed in 2008 by IEC. However, the settings for the interest region and the interest value in the clinical image do not show concrete prescribed values. Therefore, we inspected the distribution of EI by changing the interest region and the interest value for a standing-position chest radiograph image in students' medical examinations. EI50f, which is generally used, fluctuated between 41 and 136. In addition, as the area of the interest region became smaller, EI increased and the variation index increased. For the interest value, 50% (EI50h) was smaller than 85% (EI85h), and the variation index was also smaller. EI was not the absolute value in the clinical image, and immediate display of the deviation index (DI) with target exposure index (EIT) was effective of the adequacy of the radiography condition.

[Characteristic evaluation and clinical usefulness of dose area product meter at radiography].

Philips DigitalDiagnost, a digital radiographic system mounting flat panel detector (FPD), can display dose area data (DiDi dose) calculated by examination parameters. We evaluated its fundamental characteristics and compared the values of DiDi dose andactual measured data obtained by the area dose product meter (PD-4100L). Tendency of varied values of mAs, X-ray tube values and exposure area from both the area dose product meter and the DiDi dose were coincided. Further, in clinical images of chest PA 100 cases, chest lateral 50 cases and abdomen stand 25 cases, the determination coefficient was overly high as R(2)=0.99. Based on these results, it is clear that the DiDi dose can be treated the same as the area dose product meter. Under increasing of patient X-ray exposure dose is a concern in digital general radiography, this research indicates that maximum values of histogram obtained by DiDi dose contributes dose awareness for radiographer.