胸部放射治疗中锥形束CT与MOSAIQ系统中电子射野影像的图像配准精度比较  

Comparison of the Precision of Cone Beam CT and Electronic Portal Image Device in Guiding the Radiation Therapy for Thorax Tumor

作　　者：李晓玉[1] 钟仁明[1] 安卫军[1] 何垠波[1] 罗彩怡[1] 

机构地区：[1]四川大学华西医院肿瘤中心.放射物理技术中心,成都610041

出　　处：《华西医学》2012年第11期1645-1648,共4页West China Medical Journal

摘　　要：目的分析比较锥形束CT(CBCT)与MOSAIQ两系统用于测量胸部放射治疗(放疗)摆位误差情况。方法 2011年2月-9月,随机选择21例用热塑模固定的胸部调强治疗患者,进行同次摆位的CBCT图像采集和电子射野影像(EPID)正侧位图像采集。将CBCT图像与定位CT图像进行匹配,图像经iViewGT系统传输至MOSAIQ系统图像处理模块中与计划生成的数字重建图像(DRR)正侧位片进行匹配,分别记录两套系统图像匹配结果在X(左右)方向、Y(头脚)方向、Z(前后)方向的平移误差及CBCT的旋转误差值,计算其均值、标准差,进行统计学处理。结果本研究共获取图像106组,每组内包含一次CBCT图像和EPID图像。CBCT和MOSAIQ系统下EPID匹配结果平移误差在X、Y、Z方向分别为(0.103±0.240)cm、(0.086±0.342)cm、(0.017±0184)cm和(0.005±0.214)cm、(0.004±0.0.315)cm、(0.113±0.239)cm;旋转误差在X、Y、Z方向分别为(0.792±1.173)°、(0.130±1.407)°、(0.793±0.960)°,其中≤3°的概率分别为98.2%、97.2%、99.1%,最大绝对值分别为5°、3.4°、3.3°。两套系统在X、Y、Z三个方向的平移误差经配对样本检验,在Y方向P>0.05,在X和Z方向上P值均<0.05,两系统的测量差值有直线负相关关系。结论 CBCT和EPID在测量胸部放疗靶区中心的平移误差中差异有统计学意义,因此建议在做胸部放疗时有CBCT的情况下应优先使用。Objective To compare the cone beam CT （CBCT） and electronic portal image device （EPID） in measuring the positioning errors in guiding thorax tumor radiotherapy. Methods From February to September 2011, CBCT images and EPID images were acquired respectively for 21 patients with thorax tumor who received intensity-modulated radiation therapy （IMRT） immobilized by thermoplastic. The CBCT images were aligned with simulation planning CT images. The EPID images were acquired by anterior-posterior direction and right-left direction, which were transported to MOSAIQ system and aligned with digital reconstructed radiography （DRR） images generated by the planning system. These aligned results for CBCT images in right-left, inferior-superior and anterior-posterior directions for translation error and X, Y and Z direction for rotation error were calculated to means and standard deviations, and we compared the means with aligned results for EPID. The rotation errors for EPID images were neglected. Results A total of 106 paired samples of CBCT images and EPID images were acquired and analyzed. The translation errors for CBCT images and EPID images were （-0.103 ± 0.240） cm, （-0.086±0.342） cm, （0.017 ± 0184） cm and （0.005 ±0.214） cm, （-0.004 ± 0.0.315） cm, （-0.113 ± 0.239） cm respectively. The rotation error in X, Y and Z direction for CBCT images were （0.792 ±1.173）°, （-0.130 ±1.407）° and （0.793± 0.960）° respectively. The possibility for ≤3° in rotation errors were 98.2%, 97.2%, and 99.1%. The P value of paired sample t test for aligned results of CBCT images and EPID images was 〉 0.05 in Y direction and 〈 0.05 in X and Z directions. There was a negative line correlation between these two systems. Conclusion There is a significant difference between aligned results of CBCT and EPID systems, which indicates that CBCT is a primary choice for image guiding if available.

关 键 词：锥形束CT 电子射野影像系统 MOSAIQ系统 图像配准 

分 类 号：R730.55[医药卫生—肿瘤]