Marguet M, Bodez V
Service de physique, institut Sainte-Catherine, 84082 Avignon cedex 2, France.
Cancer Radiother. 2009 Sep;13(5):345-52. doi: 10.1016/j.canrad.2009.05.009. Epub 2009 Jul 16.
This work presents the introduction of a quality assurance program for the On-Board Imager (OBI, Varian) kVCBCT system, together with the results of 1 year monthly testing.
Firstly the geometric precision and stability of the equipment and of the associated software were evaluated using the Marker phantom. The coincidence of the accelerator isocenter and the imager isocenter was verified as well as the accuracy of the registration of kVCBCT with reference CT images. Then, the kVCBCT image quality was evaluated using the Catphan 504 phantom and ArtiScan software (Aquilab) for both full-fan (FF) and half-fan (HF) imaging modes.
The kVCBCT isocenter and image registration with correction of the table position were found to be within a tolerance of 2.0mm. Concerning the kVCBCT image quality, image noise and uniformity, the Hounsfield units (HU) stability and linearity, geometric distorsion and high contrast resolution were all found to be within the manufacturer's recommendations for both FF and HF modes. However, the low contrast resolution for the HF mode did not meet the manufacturer's specifications.
The quality assurance tests introduced have defined the initial system characteristics and their evolution during a period of 1 year, demonstrating the stability of the OBI.
本研究介绍了一种针对机载成像仪（OBI，瓦里安公司）千伏锥形束CT（kVCBCT）系统的质量保证方案，以及为期1年的月度测试结果。
首先，使用标记物体模评估设备及其相关软件的几何精度和稳定性。验证加速器等中心与成像仪等中心的重合性，以及kVCBCT与参考CT图像配准的准确性。然后，使用Catphan 504体模和ArtiScan软件（Aquilab）对全扇区（FF）和半扇区（HF）成像模式下的kVCBCT图像质量进行评估。
发现kVCBCT等中心以及校正床位置后的图像配准在2.0毫米的公差范围内。关于kVCBCT图像质量、图像噪声和均匀性、亨氏单位（HU）稳定性和线性、几何畸变以及高对比度分辨率，在FF和HF模式下均发现其在制造商推荐范围内。然而，HF模式下的低对比度分辨率未达到制造商的规格要求。
所引入的质量保证测试确定了初始系统特性及其在1年期间的演变情况，证明了OBI的稳定性。
