アジア圏で開催される国際学会での研究発表のススメ Development of Noise Simulation System for Optimization of Imaging Conditions in Digital Radiography
Purpose: This study was performed to develop a computerized method to optimize imaging conditions and image quality based on simulation images. We tried to develop a prototype system and ensure consistency between the resulting images and actual images obtained using a digital X-ray imaging system. Methods and Materials: An RQA5 X-ray spectrum was used for determination of input-output characteristic and noise power spectrum (NPS) in an indirect-type flat-panel detector (FPD) system. The relationship between tube current-time product (mAs), exposure dose at the detector surface, and pixel values of images was addressed and a conversion function was then created. The incident quantum numbers determined from the conversion function were input into random values generator and image noise was simulated. Simulation images provided at different noise levels were compared with the actual images provided by use of the FPD system, objectively and subjectively. Results: Average NPS of actual image in each dose level were 5.39×10－6，6.77×10－6, and 3.46×10－5 and those of simulation image were 1.10×10－6, 4.53×10－6, and 4.41×10－5, respectively. In observers study, both images showed almost the same signal detectability which decreased with decreasing exposure dose. It was confirmed that image noise was simulate almost properly. Conclusions: The present system could allow us to estimate necessary dose from image quality and also to estimate image quality from exposure dose. These results suggested that appropriate exposure dose could be determined based on necessary image quality using the simulation images.
日本放射線技術學會雜誌 68(2), 179-180, 2012-02-20
Japanese Society of Radiological Technology = 日本放射線技術学会