We investigated the longitudinal positional dependence of CT number in 320-row Cone Beam Computed Tomography (CBCT) volume scan (320-row volume scan) using a simple geometric phantom (SGP) and a chest simulation phant...We investigated the longitudinal positional dependence of CT number in 320-row Cone Beam Computed Tomography (CBCT) volume scan (320-row volume scan) using a simple geometric phantom (SGP) and a chest simulation phantom (CSP) in order to evaluate its effect on proton range calculation. The SGP consisted of lung substitute material (LSM) and a cylindrical phantom (CP) made of high-density polyethylene. The CSP was an anthropomorphic phantom similar to the human chest. The two phantoms were scanned using 320-row volume scan in various longitudinal positions from the central beam axis. In experiments using the SGP, an image blur at the boundary of the two materials became gradually evident when the LSM was placed far away from the beam central axis. The image blur of the phantom was consistent with the gradation in CT number. The maximum difference in CT numbers between the 64-row helical scan and 320-row volume scan at the boundary of the two materials was consistent with approximately 50% of the relative proton stopping power. In contrast, the CT number profile in each longitudinal position was fairly consistent and longitudinal positional dependence rarely occurred in the CSP experiments. Pass lengths of CT beams through areas with widely different electron densities were shorter, and thus did not significantly impact CT numbers. Based on findings from the CSP experiments, we considered 320-row volume scan to be feasible for proton range calculation in clinical settings, although the relatively large longitudinal positional dependence of CT number should be accounted for when doing so.展开更多
目的从定量角度初步探讨正常人肺实质肺循环及体循环的血流构成比情况,并比较正常不同区域灌注参数的差异,进一步探讨320排低剂量CT肺灌注技术的可行性和优越性。方法搜集胸片发现"可疑肺结节"、怀疑肿瘤肺转移或者食管癌患...目的从定量角度初步探讨正常人肺实质肺循环及体循环的血流构成比情况,并比较正常不同区域灌注参数的差异,进一步探讨320排低剂量CT肺灌注技术的可行性和优越性。方法搜集胸片发现"可疑肺结节"、怀疑肿瘤肺转移或者食管癌患者需行胸部CT增强扫描者,最终将20例正常资料纳入研究。采用320排CT(Aquilion One,日本东芝医疗器械公司)进行肺容积扫描,扫描参数:电压80 k V,电流70 m A,采用自适应迭代剂量降低方法进行图像重建,后处理用最大斜率法数学模型,对容积数据用图像后处理软件进行分析,生成4条时间-密度曲线,并记录各个曲线达峰时间;分析得到肺实质伪彩色血流灌注图像,分别显示肺动脉血流量(PAF)、支气管动脉血流量(BAF)及灌注指数[PI,PI=PAF/(PAF+BAF)];然后分别从重力方向(腹侧、中间、背侧)和非重力方向(上部、中间、下部)评价,各个区域均选择连续3个层面的图像进行测值,分别获得每个区域的平均灌注参数(PAF、BAF、PI值)。用单因素方差分析正常组肺实质重力与非重力方向各个区域肺灌注的差异。结果本研究每位受检者总的辐射剂量为4.02 m Sv。正常肺实质组灌注参数PAF在重力方向腹侧、中间、背侧分别为(123.2±32.9)ml·min^(-1)·100ml^(-1)、(137.1±33.6)ml·min^(-1)·100ml^(-1)、(158.5±38.7)ml·min^(-1)·100ml^(-1);PAF在重力方向差异有统计学意义(F=13.29,P<0.001),但BAF、PI差异无统计学意义。非重力方向上部、中间、下部PAF、BAF、PI差异均存在统计学意义(P<0.05),但两两比较,各个参数仅下部与上部差异有统计学意义(P<0.05)。结论 320排低剂量CT灌注成像技术能从定量角度评估肺实质肺循环和体循环血流构成比情况。正常肺实质主要由肺循环肺动脉供血,大约为98.76%,体循环支气管动脉供血所占比例较小,PAF、BAF均受重力及血流分布影响。展开更多
文摘We investigated the longitudinal positional dependence of CT number in 320-row Cone Beam Computed Tomography (CBCT) volume scan (320-row volume scan) using a simple geometric phantom (SGP) and a chest simulation phantom (CSP) in order to evaluate its effect on proton range calculation. The SGP consisted of lung substitute material (LSM) and a cylindrical phantom (CP) made of high-density polyethylene. The CSP was an anthropomorphic phantom similar to the human chest. The two phantoms were scanned using 320-row volume scan in various longitudinal positions from the central beam axis. In experiments using the SGP, an image blur at the boundary of the two materials became gradually evident when the LSM was placed far away from the beam central axis. The image blur of the phantom was consistent with the gradation in CT number. The maximum difference in CT numbers between the 64-row helical scan and 320-row volume scan at the boundary of the two materials was consistent with approximately 50% of the relative proton stopping power. In contrast, the CT number profile in each longitudinal position was fairly consistent and longitudinal positional dependence rarely occurred in the CSP experiments. Pass lengths of CT beams through areas with widely different electron densities were shorter, and thus did not significantly impact CT numbers. Based on findings from the CSP experiments, we considered 320-row volume scan to be feasible for proton range calculation in clinical settings, although the relatively large longitudinal positional dependence of CT number should be accounted for when doing so.
文摘目的从定量角度初步探讨正常人肺实质肺循环及体循环的血流构成比情况,并比较正常不同区域灌注参数的差异,进一步探讨320排低剂量CT肺灌注技术的可行性和优越性。方法搜集胸片发现"可疑肺结节"、怀疑肿瘤肺转移或者食管癌患者需行胸部CT增强扫描者,最终将20例正常资料纳入研究。采用320排CT(Aquilion One,日本东芝医疗器械公司)进行肺容积扫描,扫描参数:电压80 k V,电流70 m A,采用自适应迭代剂量降低方法进行图像重建,后处理用最大斜率法数学模型,对容积数据用图像后处理软件进行分析,生成4条时间-密度曲线,并记录各个曲线达峰时间;分析得到肺实质伪彩色血流灌注图像,分别显示肺动脉血流量(PAF)、支气管动脉血流量(BAF)及灌注指数[PI,PI=PAF/(PAF+BAF)];然后分别从重力方向(腹侧、中间、背侧)和非重力方向(上部、中间、下部)评价,各个区域均选择连续3个层面的图像进行测值,分别获得每个区域的平均灌注参数(PAF、BAF、PI值)。用单因素方差分析正常组肺实质重力与非重力方向各个区域肺灌注的差异。结果本研究每位受检者总的辐射剂量为4.02 m Sv。正常肺实质组灌注参数PAF在重力方向腹侧、中间、背侧分别为(123.2±32.9)ml·min^(-1)·100ml^(-1)、(137.1±33.6)ml·min^(-1)·100ml^(-1)、(158.5±38.7)ml·min^(-1)·100ml^(-1);PAF在重力方向差异有统计学意义(F=13.29,P<0.001),但BAF、PI差异无统计学意义。非重力方向上部、中间、下部PAF、BAF、PI差异均存在统计学意义(P<0.05),但两两比较,各个参数仅下部与上部差异有统计学意义(P<0.05)。结论 320排低剂量CT灌注成像技术能从定量角度评估肺实质肺循环和体循环血流构成比情况。正常肺实质主要由肺循环肺动脉供血,大约为98.76%,体循环支气管动脉供血所占比例较小,PAF、BAF均受重力及血流分布影响。
