从分段注量计算得到的纹理特征作为容积调强放疗（VMAT）的调制指数。

Textural feature calculated from segmental fluences as a modulation index for VMAT.

作者信息

Park So-Yeon, Park Jong Min, Kim Jung-In, Kim Hyoungnyoun, Kim Il Han, Ye Sung-Joon

机构信息

Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea; Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Republic of Korea.

Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea; Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea; Biomedical Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea; Center for Convergence Research on Robotics, Advance Institutes of Convergence Technology, Suwon, Republic of Korea.

出版信息

Phys Med. 2015 Dec;31(8):981-990. doi: 10.1016/j.ejmp.2015.07.143. Epub 2015 Sep 19.

DOI:10.1016/j.ejmp.2015.07.143

PMID:26392169

Abstract

PURPOSE

Textural features calculated from various segmental fluences of volumetric modulated arc therapy (VMAT) plans were optimized to enhance its performance to predict plan delivery accuracy.

METHODS

Twenty prostate and twenty head and neck VMAT plans were selected retrospectively. Fluences were generated for each VMAT plan by summations of segments at sequential groups of control points. The numbers of summed segments were 5, 10, 20, 45, 90, 178 and 356. For each fluence, we investigated 6 textural features: angular second moment, inverse difference moment, contrast, variance, correlation and entropy (particular displacement distances, d = 1, 5 and 10). Spearman's rank correlation coefficients (rs) were calculated between each textural feature and several different measures of VMAT delivery accuracy.

RESULTS

The values of rs of contrast (d = 10) with 10 segments to both global and local gamma passing rates with 2%/2 mm were 0.666 (p <0.001) and 0.573 (p <0.001), respectively. It showed rs values of -0.895 (p <0.001) and 0.727 (p <0.001) to multi-leaf collimator positional errors and gantry angle errors during delivery, respectively. The number of statistically significant rs values (p <0.05) to the changes in dose-volumetric parameters during delivery was 14 among a total of 35 tested parameters.

CONCLUSIONS

Contrast (d = 10) with 10 segments showed higher correlations to the VMAT delivery accuracy than did the conventional modulation indices.

摘要

目的

对从容积调强弧形治疗（VMAT）计划的各种分段注量中计算出的纹理特征进行优化，以提高其预测计划执行准确性的性能。

方法

回顾性选取20例前列腺和20例头颈部VMAT计划。通过对控制点连续组的分段求和，为每个VMAT计划生成注量。求和的分段数分别为5、10、20、45、90、178和356。对于每个注量，我们研究了6种纹理特征：角二阶矩、逆差矩、对比度、方差、相关性和熵（特定位移距离，d = 1、5和10）。计算了每个纹理特征与VMAT执行准确性的几种不同度量之间的Spearman等级相关系数（rs）。

结果

10个分段且d = 10时对比度的rs值与全局和局部2%/2 mm伽马通过率分别为0.666（p <0.001）和0.573（p <0.001）。它与执行过程中多叶准直器位置误差和机架角度误差的rs值分别为 -0.895（p <0.001）和0.727（p <0.001）。在总共35个测试参数中，与执行过程中剂量体积参数变化具有统计学显著rs值（p <0.05）的数量为14个。