心血管撮影装置におけるノイズ低減画像処理を使用した線量低減化の検討

抄録

The aim of this study is to establish radiation exposure dose reduction protocols during cardiac intervention by decreasing the entrance dose at flat panel detector (FPD) with image quality evaluations. For measuring entrance surface dose (ESD), we have used a Radical 9015 dosimeter (6 cc ion chamber) placed under 20 cm thick acrylic plates at the patient’s entrance reference point. We performed an image quality assessment based on quantitative as well as visual evaluation of the images obtained via current and dose reduction protocols. The visual evaluation was performed by measuring the signal to noise ratio and contrast using a cine/digital angiography cardiac phantom. The quantitative evaluation was performed by cardiologists and radiological technologists using the five-point scale method. For the dose reduction protocol, we used an image noise reduction technique to prevent the deterioration of image quality. The ESDs for the fluoroscopy and digital cine in the dose reduction protocol were 18.0 mGy/min and 0.18 mGy/frame, respectively, which corresponded to 81% and 49% of the ESD in the current protocol. Our results reveal that the ESD for fluoroscopy was lower than the diagnostic reference level (20 mGy/min) for interventional radiology. We recommend a lower dose setting and the maintenance of image quality using noise reduction techniques. This will ensure use of a lower FPD entrance dose compared to the initial dose setting currently recommended by manufacturers.