[New method of screening chest radiography with computer analysis of respiratory kinetics].

To develop a new method of screening chest radiography that would provide respiratory kinetics easily and automatically using flat-panel-detector capacitated fluoroscopy, we carried out a motion analysis of the diaphragm at several respiratory phases. We obtained five chest radiographs of healthy volunteer at five respiratory phases, from maximum inspiration to normal expiration. The edges of the diaphragm were enhanced by the first derivative filter, which select edge graduents within a limited range of orientations, and were detected by thresholding and analysis of connectivity in the horizontal direction. We measured the distance from the apex to the diaphragm as well as the changes at each phase. The apex was determined previously at the step of lung-region recognition. At the costophrenic angle, the change in the distance from the apex to the diaphragm was 2.44 cm on the right and 3.06 cm on the left, while at the paramedian region the changes were 0.74 cm on the right and 1.36 cm on the left. This new method of chest examination with computer analysis can provide information on diaphragm kinetics during respiration. In addition, it may aid in the early diagnosis of diseases such as chronic pulmonary emphysema and phrenic nerve paralysis.