Objective To investigate the image features,categories,and clinical significances of Pneumoconiosis Ⅲ with large shadow.Methods The research is based on the analysis of image features of 168 pneumoconiosis Ⅲ patients who are directly diagnosed by qualified medical professionals in our institution.These image features are large shadows bigger than 2 cm×1 cm which can be observed by high kilovolt chest radiographs,DR chest radiography and chest CT scan.Results Large shadows bigger than 2 ×1 cm show noticeable imaging characteristics,like distribution of superior and middle lung regions (95.2％),irregular shapes (97.6％),splayed or sausage like changes on both sides perpendicular with ribs (89.2％),small shadows of pneumoconiosis (98.8％),and convergence of large shadow to hilum or mediastinal (53.6％).CT scan is significantly better than DR radiography on detection rate of focal emphysema,focal cavities and swollen lymph node of mediastinal.Conclusion Combining the image features of high kilovolt chest radiographs,DR chest radiographs and CT scan are the main methods to identify the shadows,and thus direct diagnose pneumoconiosis Ⅲ;CT scan plays an important role in differential diagnosis.

Objective To investigate the image features,categories,and clinical significances of Pneumoconiosis Ⅲ with large shadow.Methods The research is based on the analysis of image features of 168 pneumoconiosis Ⅲ patients who are directly diagnosed by qualified medical professionals in our institution.These image features are large shadows bigger than 2 cm×1 cm which can be observed by high kilovolt chest radiographs,DR chest radiography and chest CT scan.Results Large shadows bigger than 2 ×1 cm show noticeable imaging characteristics,like distribution of superior and middle lung regions (95.2％),irregular shapes (97.6％),splayed or sausage like changes on both sides perpendicular with ribs (89.2％),small shadows of pneumoconiosis (98.8％),and convergence of large shadow to hilum or mediastinal (53.6％).CT scan is significantly better than DR radiography on detection rate of focal emphysema,focal cavities and swollen lymph node of mediastinal.Conclusion Combining the image features of high kilovolt chest radiographs,DR chest radiographs and CT scan are the main methods to identify the shadows,and thus direct diagnose pneumoconiosis Ⅲ;CT scan plays an important role in differential diagnosis.