EVALUATION OF IMAGE PROCESSING TECHNIQUES OF PHOTON-COUNTING X-RAY RADIOGRAPHY IN THORACIC DIAGNOSTIC IMAGING

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[INTRODUCTION] Photon counting X-ray radiography (quantum radiography : QR) offers digital images produced by directly measuring the number of photons of an X-ray which have permeated through the object. The photons are calculated by means of CdTe multi-line sensor. It gives a high quality image with the features of high sensitivity and good linearity over the wide range of density. X-ray machine used is newly devised QR system (Shimadzu, Kyoto, Japan).[PURPOSE] To evaluate the utility of QR on detection of pulmonary lesions, clinical studies were performed with comparison of conventional chest radiography (CONV).[MATERIALS AND METHODS] Forty two patients were included in this study ; eighteen lung cancer, nine metastatic lung tumor, five interstitial pneumonia, four tuberculosis, one lymphoma, one hamartoma, one hypersensitivity pneumonitis, one viral pneumonia, one pneumoconiosis, one organizing pneumonia. Eight radiologists scored QR comparing with CONV by 7-point rating scale metho … More d. All observers scored the description of normal structures and abnormal shadows in the high film density area (HFDA : peripheral lung field) and in the low film density area (LEDA : retrocardiac or subdiaphragmatic area). The results were analyzed by Wilcoxon signed rank sum test.[RESULTS] QR was superior to CONV in the depiction of all normal structures and all kinds of abnormal shadows in the whole area (p<0.000 1). QR was superior to CONY in the-description of multiple pulmonary nodules especially in LFDA.[DISCUSSION] QR is a kind of digital imaging technique. This is quite different from conventional radiography or current digital radiography on the point that QR directly counts the number of photons which come into the semi-conductive sensor unit without any other media, for example, screen-film system or storage phosphor plate. Clinically, QR was superior to CONY for description of many kinds of normal structures and abnormal shadows in the whole film density area. This result might reflect the superior density resolution of QR and its superiority of density resolution might surpass slight inferiority of spatial resolution especially in the clinical evaluation. QR was thought to be a very useful digital diagnostic imaging of the thorax with wide dynamic range. Less