Compass三维剂量验证系统在鼻咽癌容积旋转调强放射治疗计划剂量验证中的应用

目的:探讨Compass三维剂量验证系统在鼻咽癌容积旋转调强放射治疗(VMAT)计划剂量验证中产生的剂量差异,并分析其原因。方法:选取17例鼻咽癌患者,在Monaco上制定VMAT计划并将其传至Compass,运用Compass自身计算的剂量(CD)和通过实测重建的剂量(RD)两种方法验证靶区和危及器官(OAR)的γ通过率、D1%、D99%、Dmean等参数。结果:治疗计划系统(TPS)-CD的所有γ通过率均>97.5%,TPS-RD的所有γ通过率均>95.0%,且TPS-CD的每一个γ通过率均大于TPS-RD中对应的γ通过率,两者靶区的γ通过率比较差异有统计学意义(t=2.110,t=2.749,t=2.489,t=2.687,t=2.798,t=2.881,t=2.921;P<0.05),但两者在OAR比较则无统计学意义。TPS-RD的靶区D1%、Dmean及D99%的三项指标绝对剂量差均<200 cGy,百分差<2.5%,且这三项指标在TPS和RD之间的差异均无统计学意义;左右晶状体的三项指标的剂量在TPS和RD之间的差异均有明显统计学意义(t=4.328,t=4.658,t=4.210,t=4.511,t=4.896,t=5.241;P<0.05);脊髓、脑干、左右腮腺等OAR的D99%在TPS和RD之间的差异有统计学意义(t=4.018,t=4.035,t=3.646,t=4.112;P<0.05),Dmean和D1%在TPS和RD之间的差异均无统计学意义。结论:Compass三维剂量验证系统在VMAT计划剂量验证中可直观、快速的分析出靶区和OAR的理论和实际照射剂量差异,为剂量的精准实施提供数据支持

Oprimization and Processing Method Research of CBCT Images

CbCT图像中低密度分辨率不够,同时CbCT图像上各组织的CT值和物理密度非线性对应,使得在CbCT图像上的勾画和剂量计算难以进行。采用数据图像处理的方法,对CbCT图像进行增强,同时通过对同一病人的CbCT和CT图像的配准,根据CT图像的CT值,对CbCT图像的CT值进行调整,使得CbCT图像的CT值分布和CT图像接近,为最终使CbCT图像可以被直接用来勾画和参与剂量计划打下基础。Noise affects images produced by CBCT units by reducing low contrast resolution,and CT values of various tissue regions are different from those in CT.These make the sketch on the CBCT images and CBCT-based dose calculation difficult.In this paper, image processing methods were used to enhance CBCT images,and the patient' s CBCT and CT images were registered,CT values in CBCT images were adjusted according to those in CT images in the same region.The work make it possible to use CBCT image in adaptive treatment plan directly.国家自然科学基金(编号:61001144); 福建省自然科学基金(编号:2010J01137)~

The Optimized Image Correction Algorithm for the Middle Area of Grids

常规放疗中模拟定位机影像增强器采集的图像常存在失真,为了保证放疗的精度,必须进行矫正,为此提出一种以点到直线距离为目标函数的图像矫正算法.在综合考虑矫正的速度、精度、平滑性的前提下,先采用基于一次线性基的移动最小二乘法对图像进行了矫正,取得了比较理想的结果;进一步,利用矫正后各线条应该为直线这一特征增加了参考点的数量,使交叉点中间区域也有了参考点.矫正结果显示,矫正之后各网格线呈现更理想的直线,交叉点之间的区域矫正比只考虑交叉点的矫正算法理想.当参考点增加到2 000多个点时,算法运行时间仍然较短.In conventional radiotherapy,the images obtained by the image intensifier of radiotherapy simulator are often distorted.In order to ensure the accuracy of radiotherapy,corrections must be conducted.Hence,an image correction algorithm is proposed with the objective function based on the distance of a point to a straight line.Given the correction speed,precision and smoothness,the moving least square method based on the primary linear base is adopted to correct images firstly and the results are satisfactory.Furthermore,on account of the characteristic that corrected grid lines should be straight,the number of reference points is increased so that the middle area of intersection points has reference points too.The corrected results present that after the correction,grid lines are more similar to straight line,and the correction effects of intersection areas are better than those of correction algorithm,which only take into account the intersection points.In addition,although more than 2 000 reference points are increased,the algorithm running time remains short.国家自然科学基金(61001144);福建省自然科学基金(2010J01137