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目的探讨胸腹肿瘤在平均密度和最大密度投影CT和4D-CT中的表现特征,寻求快速准确勾画运动靶区范围的方法。方法患者在自由呼吸状态下进行“电影”(Cine)模式扫描,每个床位扫描持续时间等于患者的一个呼吸周期加上1秒。扫描后生成平均密度(AIP)和最大密度投影(MIP)CT,并进行4D-CT重建。用Nomos CorvusV8.0放疗计划系统和IBAOmniPro I’mRT软件,分析靶区在AIP、MIP CT及两个极限呼吸相位4D-CT中的大小及其相互关系;自制周期运动体模分析窗宽/窗位对平均密度和最大密度投影CT中靶区形态的影响。结果 AIP CT中靶区大于两个极限相位4D-CT中的靶区,其比值分别为1.30和1.07;MIP CT中的靶区大于两个极限相位4D-CT中的靶区,其比值分别为1.57和1.21。结论用AIP CT和MIP CT能快速确定靶区的运动范围,减少靶区勾画的劳动强度,但恰当的窗宽窗位是关键。
Objective To explore the characteristics of chest and abdomen tumors in average density and maximum density projection CT and 4D-CT, and to seek a method for quickly and accurately mapping the range of target. Methods Patients underwent a Cine mode scan in a free-breathing state with each bed scan duration equal to one patient’s breathing cycle plus 1 second. After scanning, average density (AIP) and maximum density projection (MIP) CT were generated and 4D-CT reconstruction was performed. Using Nomos Corvus V8.0 radiotherapy planning system and IBAOmniPro I’mRT software to analyze the target size in AIP, MIP CT and two limit respiratory phase 4D-CT size and their relationship; homemade periodic motion phantom analysis window width / window Effect of Positions on Morphology of Target Regions in CT Images with Average Density and Maximum Density. Results The target area of AIP CT was larger than that of 4D-CT in two limit phases, and their ratios were 1.30 and 1.07, respectively. The target area in MIP CT was larger than that of 4D-CT in two limit phases, 1.57 and 1.21. Conclusion AIP CT and MIP CT can quickly determine the target range of motion and reduce the labor intensity of the target area, but the appropriate window width is the key.