锥形束CT快速扫描模式在胸腹部肿瘤放射治疗中的应用分析

目的 比较锥形束CT(CBCT)标准和快速两种扫描模式在胸腹部肿瘤放射治疗摆位误差测定中的差异,探讨快速扫描模式下的摆位误差测定,并探讨进行在线修正的可行性。方法 选取本院2013年10月8日至2014年11月8日收治的50例胸腹部肿瘤患者,在首次行容积旋转调强放疗(VMAT)前进行顺时针方向标准扫描模式CBCT扫描,之后立即行逆时针方向快速扫描模式CBCT扫描,按照扫描模式将所有患者图像分为快速模式组和标准模式组,两组图像分别与计划CT图像进行配准并对两组配准结果进行比较分析。由1名放疗医生、1名物理师和1名技术员采用主观质量评分法(MOS)进行图像质量评价。结果 x、y、z轴平移和旋转方向的摆位误差在快速模式组与标准模式组之间的差值分别是(0.2±0.2)、(-0.6±0.4)和(-0.2±0.3)mm与(0.2±0.1)°、(0.0±0.1)°和(0.1±0.1)°,两组结果差异无统计学意义(P>0.05);两组摆位误差统计结果之间高度相关(r=0.92~0.98,P<0.01);两组摆位误差统计结果之间具有较满意一致性(Kappa=0.82~0.94)。标准模式组和快速模式组的MOS评分平均值分别为3.9、4.1、3.8和3.6、4.0、3.8,结果差异无统计学意义(P>0.05)。结论 快速扫描模式与标准扫描模式采集的图像在胸腹部肿瘤摆位误差测定并在线修正中具有高度相关性和一致性,且图像质量不会明显变差,CBCT快速扫描模式可应用于胸腹部肿瘤放射治疗摆位误差测定和在线修正。

The analysis of fast pattern Cone beam CT for thorax and abdomen radiotherapy

Objective To compare and analyze the difference of setup errors associated with radiotherapy for thorax and abdomen cancer with Cone beam CT (CBCT) between standard scan pattern and fast scan pattern, and to investigate the feasibility of online calibration in fast scan pattern for radiotherapy of thorax and abdomen cancer. Methods A total of 50 patients with thorax and abdomen cancer were selected and all the patients were designated either clockwise standard CBCT scan and anticlockwise fast CBCT scan before first volumetric modulated arc therapy (VMAT) either. The images of two scan patterns and the setup error of thorax and abdomen cancer were also compared. A physician, a physicists and a technician evaluated the quality of all images using the mean opinion score (MOS) method. Results The deviation between setup error from standard imaging pattern and setup error from fast imaging pattern of x,y,z axis translation and rotation were (0.2±0.2), (-0.6±0.4), (-0.2±0.3) mm and (0.2±0.1)°, (0.0±0.1)°, (0.1±0.1)°, which was not statistically significant (P>0.05). The setup error from standard imaging pattern and setup error from fast imaging pattern were highly correlated with statistical significance (r=0.92-0.98, P<0.01). The two types of imaging models had satisfactory consistency (Kappa=0.82-0.94). The average score results of MOS in standard and fast imaging pattern were 3.9, 4.1, 3.8 and 3.6, 4.0, 3.8, respectively, and the differences were not statistically significant (P>0.05). Conclusions Fast imaging pattern has high correlation and consistency with the standard imaging model in the CBCT setup error correction, and the quality of images has no significant deterioration. The CBCT fast imaging pattern could be chosen to determine the setup error using online calibration for imaging thorax and abdomen cancer.