Background: Recent advances in X-ray detector and digital image post-processing technology have facilitated the performance of sequential radiography with extremely low doses [1]. Lung and cardiac function can be assessed in a simple, low dose and cost-effective way with dynamic chest radiography based on a flat-panel detector (FPD). Of particular note is blood flow evaluation based on changes in pixel values on dynamic chest radiographs without contrast media.

Previous research: There have been many reports showing the feasibility of pulmonary densitometry [2-6]. Some studies succeeded in blood circulation mapping based on changes in pixel value during cardiac pumping [7-9]. However, there has been no report demonstrating a normal projection of cardiothoracic blood circulation on dynamic chest radiographs, which is essential as diagnostic criteria for the diagnosis of blood flow disorders with dynamic chest radiography.

Long-term goal: To develop a simple, low dose, and cost-effective chest functional imaging with a dynamic FPD, which allows us to assess the diaphragmatic movement, local pulmonary ventilation, and cardiothoracic blood circulation.

This study was performed to establish a normal cardiothoracic blood circulation map projected as changes in pixel value on dynamic chest radiographs and to evaluate the diagnostic performance of blood flow disorders based on the newly-developed diagnostic criteria in clinical cases.