用PrecisePLAN系统分析锥形束CT图像体积精度

Precise Plan in the analysis of volume precision in Synergy^(TM) conebeam CT image

目的建立检测SynergyTM锥形束CT图像体积精度的方法。方法分别将QUASARTM模体中心置于SynergyTM系统CBCT的中心及沿加速器头脚方向偏离等中心5、8、10 cm处进行扫描,在三维重建图像中测量不同模体的体积,并与FBCT结果和原标称值进行对比,从而检验CBCT的体积精度,并用Precise PLAN系统进行分析。结果中球在中心处与偏中心5、8 cm处测量的平均值与标称值相差1.5%。小球在中心处与偏中心5、8、10 cm处测量的平均值与标称值相差8.1%。大立方体在中心处与偏中心5、8、10 cm处测量的平均值与标称值相差0.8%。小立方体在中心处与偏中心5、8、10 cm处测量的平均值与标称值相差2.9%。结论在SynergyTM锥形束CT有效扫描重建范围内,重建体积精度满足临床要求,并且与偏离锥形束CT中心的距离无关。

Objective A method of checking the volume precision in SynergyTM conebeam CT image. Methods To scan known phantoms（big, middle, small spheres, cubes and cuniform cavum） at different positions（CBCT centre and departure centre from 5, 8, 10 cm along the accelerator G-T way）with conebeam CT, the phantom volume of reconstructed images were measure. Then to compared measured volume of Synergy^TM conebeam CT with fanbeam CT results and nominal values. Results The middle spheres had 1.5% discrepancy in nominal values and metrical average values at CBCT centre and departure from centre 5, 8 cm along accelerator G-T way. The small spheres showed 8.1%, with 0.8% of the big cube and 2.9% of small cube, in nominal values and metrical average values at CBCT centre and departure from centre 5, 8, 10 cm along the accelerator G-T way. Conclusion In valid scan range of Synergy^TM conebeam CT, reconstructed precision is independent of the distance deviation from the center.