Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning.
Phantom investigation of 3D motion-dependent volume aliasing during CT simulation for radiation therapy planning.
复制标题
在放射治疗计划中，CT模拟过程中3D运动依赖性量混叠的幻影研究。
DOI：
10.1186/1748-717x-2-10
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发表时间：
2007-02-24
影响因子：
3.6
通讯作者：
Salter, Bill J.
中科院分区：
文献类型：
--
作者：
Tanyi, James A.;Fuss, Martin;Varchena, Vladimir;Lancaster, Jack L.;Salter, Bill J.
在存在3D目标运动的情况下，在非门控快速和慢速扫描采集CT期间量化体积和位置混叠。对动态球形靶（直径1和3.15 cm）进行单层快速、单层慢速和多层快速扫描螺旋CT，并将其嵌入拟人体模中。研究了临床观察到的肿瘤运动参数的典型3D靶运动。运动偏移包括S-I方向上± 5、± 10和± 15 mm的位移，分别与A-P和侧向方向上± 5和± 2 mm的恒定位移同步。对于每个目标，扫描技术，和运动偏移，八个不同的初始运动扫描相位关系进行了研究。观察到靶体积高估的预期总体趋势。真实物理靶体积的平均百分比高估通常随着靶运动幅度和靶直径的减小而增加。与快速扫描相比，慢速扫描的高估百分比更大，并且更好地近似时间平均运动包络。运动引起的质心误表示是在S-I方向的快速扫描技术，和横轴方向的慢扫描技术。对于< 5 mm的切片宽度，高估是相当均匀的，超过5 mm则存在严重高估。描述临床相关3D运动的靶的非门控CT成像导致靶体积的混淆高估和质心位置的错误表示，物理靶几何结构和CT生成的靶几何结构之间几乎没有相关性。慢扫描技术是一种表征目标时均位置的实用方法。快速扫描技术提供了一个更可靠的，虽然仍然扭曲，目标边缘。
To quantify volumetric and positional aliasing during non-gated fast- and slow-scan acquisition CT in the presence of 3D target motion. Single-slice fast, single-slice slow, and multi-slice fast scan helical CTs were acquired of dynamic spherical targets (1 and 3.15 cm in diameter), embedded in an anthropomorphic phantom. 3D target motions typical of clinically observed tumor motion parameters were investigated. Motion excursions included ± 5, ± 10, and ± 15 mm displacements in the S-I direction synchronized with constant displacements of ± 5 and ± 2 mm in the A-P and lateral directions, respectively. For each target, scan technique, and motion excursion, eight different initial motion-to-scan phase relationships were investigated. An anticipated general trend of target volume overestimation was observed. The mean percentage overestimation of the true physical target volume typically increased with target motion amplitude and decreasing target diameter. Slow-scan percentage overestimations were larger, and better approximated the time-averaged motion envelope, as opposed to fast-scans. Motion induced centroid misrepresentation was greater in the S-I direction for fast-scan techniques, and transaxial direction for the slow-scan technique. Overestimation is fairly uniform for slice widths < 5 mm, beyond which there is gross overestimation. Non-gated CT imaging of targets describing clinically relevant, 3D motion results in aliased overestimation of the target volume and misrepresentation of centroid location, with little or no correlation between the physical target geometry and the CT-generated target geometry. Slow-scan techniques are a practical method for characterizing time-averaged target position. Fast-scan techniques provide a more reliable, albeit still distorted, target margin.