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Intro:Recently, dynamic chest radiography (DCR) has been developed to evaluate pulmonary function by flat panel detector (FPD). It can evaluate flow of the pulmonary artery and the movements of both lungs and heart without contrast agent.Objective:To check the feasibility of evaluation method of pulmonary perfusion based on temporal changes in image density captured with sequential radiography at monkeys in supine and standing positionMethod:Five monkeys were anesthetized and DCR were obtained by using FPD. Region of interest (ROI) were placed in both lung fields of the image, and the maximum change of the pixel value in the ROI were measured during one cardiac cycle of electrocardiogram. A pulmonary embolism (PE) model was induced by using a SG catheter. The pixel value change (?PV) of the lungs in normal and PE models were compared in both supine and standing position. We created an image with highest pixel value of entire image as reference value and expressed the place where the pixel value decreases compared with the reference value with red shadeResult:The pixel value change at lung had same cycle with electrocardiogram in monkeys. In the standing position, changes of pixel value decreased at upper lung and increased at lower lung as compared to the supine position. In the PE model, the ?PV was decreased at area where pulmonary blood flow was occluded and increased at contralateral lung as compared to the normal model in the supine and standing position. The raito of mean ?PV at occluded area to mean ?PV at contralateral area in the supine position was 0.30 (SD 0.15) in left PE model versus 1.24 (SD 0.42) in normal model (P = 0.027), and 0.28 (SD 0.16) in right PE model versus 0.90 (SD 0.28) in normal model (P = 0.017). These difference could expressed at the color map (image).Conclusion:DCR could detect pulmonary embolism without contrast agent at monkeys in the supine and standing position.