IMR重组技术在iCT胸部超低辐射剂量扫描中的应用

Application of Iterative Model Reconstruction Method to Ultralow Dose Chest Scan with iCT

目的比较飞利浦iCT胸部超低剂量扫描和常规剂量扫描的图像质量,探讨全模型迭代重组技术在胸部超低剂量扫描中的应用价值。方法选取临床排出肺内病变行胸部CT平扫患者60例,随机平均分为两组(A/B);A组常规剂量扫描(120 kV,70 mAs),采用滤波反投影法图像重组,B组超低剂量扫描(100 kV,25 mAs),采用全模型迭代重组技术图像重组。统计各组的有效剂量及图像噪声,按1~3分主观评分法评价纵隔大血管、外周支气管血管束和胸壁正常解剖结构的显示质量。结果 A组平均辐射剂量为(2.45±0.09)m Sv,图像噪声SD值:气管分叉处升主动脉(10.6±1.82),锁骨层面胸大肌(16.6±2.32),肩胛骨下角层面胸背部脂肪平均SD(12.6±1.45);B组平均辐射剂量为(0.54±0.03)m Sv,图像噪声SD值:气管分叉处升主动脉(4.2±0.32),锁骨层面胸大肌(7.3±0.52),肩胛骨下角层面胸背部脂肪平均SD(5.8±0.42);主观评分两组间无明显差异。结论在胸部CT扫描中采用超低辐射剂量联合全迭代重组技术可以获得满足临床诊断需求的低噪声重组图像。

Objective To explore the application value of iterative model reconstruction technique in chest ultra-low dose scanning via performing compare analysis on the image quality of Philips ICT chest ultra-low dose scans and routine dose scans.Methods A total of 60 cases of thoracic CT examination in patients undergoing clinical elimination of pulmonary lesions were selected and randomly divided into two groups(A, B). A regular dose scan(120 kV, 70 mAs) was used in Group A to reorganize the image by filtering reverse projection method. In Group B, ultra-low dose scanning was used(100 kV, 25 mAs),and the iterative model reconstruction(IMR) was used to reorganize the technology image. The effective dose and image noise of each group were evaluated by 1-3 subjective scoring method, and the display quality of the normal anatomical structure of peripheral bronchial vascular bundle and thoracic wall. Results The average radiation dose in Group A was(2.45±0.09)m Sv. Image noise(SD): Raw aorta at the bifurcation of the trachea was(10.6±1.82), the muscle at clavicle level was(16.6±2.32),chest and back fat at the lower corner of the scapula was(12.6±1.45). The average radiation dose in Group B was(0.54±0.03) mSv.Image noise(SD): Raw aorta at the bifurcation of the trachea was(4.2±0.32), the muscle at clavicle level was(7.3±0.52), chest and back fat at the lower corner of the scapula was(5.8±0.42). Conclusion In chest CT scan, low noise image can be obtained by using ultra-low radiation dose combined with full iterative reconstruction technology to meet the needs of clinical diagnosis.