千伏级锥形束CT图像质量和稳定性及三维影像体积重建精度研究  

Quantitative analysis of image quality , stability and volume precision in kilovoltage cone beam CT

作　　者：汪隽琦[1] 徐志勇[1] 胡伟刚[1] 李龙根[1] 彭佳元[1] 

机构地区：[1]复旦大学上海医学院肿瘤学系复旦大学附属肿瘤医院放疗科,上海200032

出　　处：《中华放射肿瘤学杂志》2012年第2期176-180,共5页Chinese Journal of Radiation Oncology

摘　　要：目的定量评价瓦里安加速器机载千伏级锥形束CT（CBCT）的图像质量、稳定性及三维影像体积重建精度。方法应用CBCT系统分别采用全扇形扫描和半扇形扫描方式重复扫描Catphan@600模体，用治疗计划系统评价图像质量参数（低对比度分辨率、空间分辨率、均匀性及噪声）及体积重建精度；并以常规大孔径模拟CT（FBCT）图像为基准做定量比较，观察其长期稳定性。结果CBCT空间分辨率与FBCT无差别（6lp／cm：6lp／cm，T=18．00，P〉0．05）。CBCTFull-Fan与CBCTFull-Fan低对比度分辨率均高于FBCT（1．65％与1．74％：1．03％，T=6．00，P〈0．05），其均匀性也高于FBCT（0．005与0．033：0．003，T=6．00，P〈0．05），各项对比度一噪声比也都低于FBCT（T=30．00，P〈0．05）。在有效扫描范围内CBCT体积重建精度较高且长期稳定性较好。结论千伏级CBCT图像质量差于常规FBCT，但仍可实现肿瘤和软组织成像且稳定性好和三维影像体积重建精度高。Objective To quantitatively evaluate the image quality, stability and volume precision in kilovoltage cone beam CT （CBCT） on Varian linear accelerator. Methods The Catphan 600 phantom was repeatedly scanned in the full-fan and half-fan CBCT scanning modes. A simulation fan-beam CT （FBCT） was used as a benchmark and results related to the low contrast resolution, spatial resolution, uniformity and image noise were compared with the CBCT using the treatment planning system. The comparison of image quality and long-term stability and volume precision was analyzed. Results Spatial resolution was no differences observed between FBCT and CBCT （ 6 lp/cm： 6 lp/em, T = 18.00, P 〉 O. 05 ）. Low contrast resolution was, on average, 1.65% and 1.74% for both CBCTFull-Fan and CBCTFull-Fan, and 1.03% for the FBCT （ T=6. 00, P 〈0. 05）. Uniformity was, on average, 0. 005 and 0. 033 for both, and 0. 003 for the FBCT （ T = 6. 00, P 〈 0. 05 ）. In terms of image noise, the FBCT images were superior to the CBCT （ T = 30. 00, P 〈 0. 05）. In valid scan range of the CBCT, reconstructed precision was high. There was no significant time trend in the image quality. Conclusions The image quality of kilovohage CBCT is inferior to the conventional CT. However, tumor and soft tissues are visible in the CBCT images. The image stability and reconstructed precision is satisfying.

关 键 词：体层摄影术 X线计算机 锥形束 图像质量 稳定性 体积精度 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]