瓦里安OBI系统锥形束CT图像CT值长期稳定性分析

时飞跃; 田书畅; 金洵; 秦航; 秦伟

doi:10.3969/j.issn.1000-1158.2020.01.19

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计量学报 ›› 2020, Vol. 41 ›› Issue (1) : 103-108. DOI: 10.3969/j.issn.1000-1158.2020.01.19

电离辐射、标准物质与生物计量

瓦里安OBI系统锥形束CT图像CT值长期稳定性分析

时飞跃¹,田书畅²,金洵³,秦航²,秦伟¹

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Long-term Constancy Analysis of CT Numbers for Cone-beam CT Images of a Varian OBI System

SHI Fei-yue¹,TIAN Shu-chang²,JIN Xun³,QIN Hang²,QIN Wei¹

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摘要

通过分析7种物质CT值的长期质控检测数据,评估瓦里安机载影像(OBI)系统锥形束CT(CBCT)图像CT值的稳定性。使用Catphan504模体,每月对瓦里安Clinac iX加速器配备的OBI系统进行质控检测,获取高质量头部(HQH)、标准剂量头部(SDH)和盆腔(Pelvis)3种扫描协议下的CBCT图像。使用DoseLab软件,对2017年3月至2018年2月共36个CBCT图像序列进行分析,获取CTP404模块中每种物质的CT值(记为Y)以及与标准CT值的差异(记为ΔY)。对数据进行统计分析,通过计算得到3种扫描协议下7种物质Y值的平均值、标准差和极差以及ΔY的平均值。结果表明:该瓦里安OBI系统CBCT图像CT值在12个月里总体上比较稳定; SDH和Pelvis两种扫描协议适合用于CBCT图像质量的质控和计量检测;HQH扫描协议的CBCT图像中物质CT值与标准CT值的差异,随物质相对电子密度的增加变化较大。

Abstract

The long-term constancy of CT numbers for cone-beam CT images of Varian on-board imager (OBI) system were evaluated, by analyzing the data of CT numbers for seven materials obtained from long-term quality assurance (QA) tests. QA tests for an OBI system equipped by the Varian Clinac iX linear accelerator were carried out with the Catphan504 phantom monthly. CBCT images were obtained with three scan protocols: high-quality head (HQH), standard-dose head (SDH) and Pelvis for the phantom. The DoseLab software was utilized to analyze the 36 series of CBCT images acquired from Mar. 2017 to Feb. 2018, and the CT numbers (Y) and corresponding difference from standard CT numbers (ΔY) for the seves materials were obtained.The datas were analysised by statistical method , and the mean, standard deviation and range values of Y and the mean of ΔY were obtained after calculation for the seven materials with three scan protocols. The results showed that the constancy of CT numbers of the CBCT images from the Varian OBI system was in good condition in 12 months by and large, the scan protocols of SDH and Pelvis were suitable for QA and metering tests of CBCT image quality, the difference between CT numbers of CBCT images with HQH and the standard CT numbers varied greatly with the increasing of relative electron density of material.

导出引用

时飞跃,田书畅,金洵,秦航,秦伟. 瓦里安OBI系统锥形束CT图像CT值长期稳定性分析[J]. 计量学报. 2020, 41(1): 103-108 https://doi.org/10.3969/j.issn.1000-1158.2020.01.19

SHI Fei-yue,TIAN Shu-chang,JIN Xun,QIN Hang,QIN Wei. Long-term Constancy Analysis of CT Numbers for Cone-beam CT Images of a Varian OBI System[J]. Acta Metrologica Sinica. 2020, 41(1): 103-108 https://doi.org/10.3969/j.issn.1000-1158.2020.01.19

中图分类号： TB98

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