数值逼近法确定大体肿瘤体积的物理模型研究

Gross Target Volume Delineation on PET Images by a Numerical Approximation Method Phantom Studies

采用数值逼近法设计确定肿瘤大体靶区（GTV）的半自动化软件SUV_Shape,并通过物理模型评价SUV_Shape测量GTV的准确性。使用中位容积19.61（5.88,64.56）mL,形体各异的空心插件27例次,在其内灌注不同放射性比活度[18F]-FDG溶液,并将它们固定在灌注不同放射性比活度[18F]-FDG溶液的圆柱体内,分别模拟肿瘤与周围本底,肿瘤/本底比（2.92～40.6）的实验模型4次。采集静态肿瘤模型3D PET-CT图像,用SUV_Shape软件测得模型GTVs,27例次肿瘤模型GTVs的中位体积20.56（5.1,65.16）mL。经配对t检验GTVs与GTVt无统计学差别（t=-1.27,P=0.22）,两者高度正相关Spearman相关系数rho=0.959（P〈0.01）。显示SUV_Shape程序多能够根据3D PET图像测量肿瘤模型体积。

A scheme named SUV_Shape for drawing the gross target volume（ GTV） on PET images was developed by a numerical approximation method and evaluated by several simulating tumor models. Globe-shaped,ellipsoid-shaped,cavity-shaped,leaflet-shaped,club-shaped hollow spheres were made,and their median volume was 19. 61（ 5. 88,64. 56） mL. These models filled with 23. 72 k Bq / mL ～ 162. 03 k Bq / mL [18F]-FDG representing a tumor and fixed in a barrel filled with 3. 99 k Bq / mL ～ 8. 13 k Bq / mL [18F]-FDG representing the background served as phantoms. And the tumor-background ratio ranged from 2. 92 ～ 40. 6 in the four phantoms. [18F]-FDG 3D PET-CT images of phantoms at rest were acquired. SUV_Shape scheme measured the GTV of the tumor by a numerical approximation method. The paired-t tests and Spearman＇s correlation coefficient（ rho） between GTVs and the volume of models（ GTVt） were done. The measurement error analyses were done for the GTVs. Results 27 tumor models were drawn by SUV_Shape,and their median GTVs was 20. 56（ 5. 1,65. 16） mL. In addition; these models＇ GTVt and GTVs were not significant different（ t =-1. 27,P = 0. 22）. Moreover,rho between them were 0. 959（ P〈0. 01）,which suggested they were highly relative. According to the location error was 1. 95 mm,20 tumor models＇ GTVs were within their margin of relative error; while the reminder seven models＇ GTVs were beyond them. SUV_Shape could delineate and measure the GTV of simulating tumor,and their position resolutions of sub-pixel were usually achieved.