加速器机载kV-CBCT成像参数与图像质量的定量分析

Quantitative analysis of the impact of preset imaging parameters on image quality of Linac-integrated kV-CBCT unit

采用Catphan 503模体,选用不同的扫描预设条件成像,对加速器机载千伏级锥形束CT(kV-CBCT)图像的均匀性、噪声、低对比度分辨率和空间分辨率进行评估。结果表明提高X线球管管电压管电流、增大机架旋转扫描范围、减小准直器尺寸、提高重建精度等参数有利于获得高质量锥形束CT(CBCT)图像,但同时患者将多受额外的X射线辐射,也加大X线球管和探测器等元器件的损耗。因此,临床使用中应根据患者解剖条件合理选择成像参数,这样既能保证图像质量,又尽可能降低患者的辐射剂量。

Abstract This study scanned the Catphan 503 phantoms to evaluate the uniformity, noise, low contrast resolutionand spatial resolution of Linac-integrated kV-cone beam CT image with choosing different scanning preset parame- ters, and analyzed the image variations changed with the tube voltage, tube current, collimator type, gantry scan- ning range and reconstruction precision. The results showed that improving X-ray tube voltage and current, expen- ding the scanning gantry rotation range and reducing collimator size, increasing reconstruction precision and other imaging parameters were conducive to high quality cone beam CT images. As a result, patients suffered more addi- tional X-ray radiation and X-ray tube and detector components loss increased, simultaneously Imaging preset parameters should be reasonably chosen according to the patient＇ s anatomy, which can guarantee quality and minimize patient radiation dose. scanning the image