Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy.
Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy.
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兆伏计算机断层扫描方法对螺旋断层放射治疗中设置验证和自适应剂量计算的影响
DOI：
10.1186/s13014-018-0989-y
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发表时间：
2018-04-27
期刊：
影响因子：
--
通讯作者：
Yin Y
中科院分区：
文献类型：
--
作者：
Zhu J;Bai T;Gu J;Sun Z;Wei Y;Li B;Yin Y
背景评估治疗前兆伏级计算机断层扫描（MVCT）扫描方法对螺旋断层放射治疗中设置验证和自适应剂量计算的效果。方法采用TomoTherapy物理师工作站对拟人化异质胸部和盆腔体模进行虚拟靶区规划，并使用TomoTherapy兆伏级图像引导放疗进行扫描 （IGRT）系统由六组选项组成：“精细”、“正常”和“粗略”三种不同的采集节距（AP）通过乘以2个不同的相应重建间隔（RI）来实现。为了模拟患者设置的变化，每个模型分别在三个正交方向上手动移动 5 毫米。分析了MVCT扫描选项对图像质量（CT数量和噪声）、自适应剂量计算偏差和位置校正变化的影响。结果“精细”节距的MVCT扫描时间大约是“正常”设置的两倍，是“粗略”设置的3倍，所有这些都不会受到不同RI的影响。使用不同 AP 的 MVCT 在不同密度的 7 个选定区域内提供几乎相同的 CT 数和图像噪声。不同节距采集的连续 MVCT 图像重叠在一起得出的自适应剂量计算的 DVH 曲线，仿真脊髓 (p= 0.761 & 0.277)、心脏 (p= 0.984 & 0.978)、肺 (p= 0.992 & 0.980)、软组织的截距和斜率的所有 p 值均无显着差异(p= 0.319 & 0.951) 和骨骼结构 (p= 0.960 & 0.929) 在最精细和最粗糙的 MVCT 系列之间。此外，伽马指数分析表明，与“精细”MVCT 计算的剂量分布相比，“正常”或“粗略”MVCT 分析的点中只有 0.2% 或 1.1% 不符合定义的伽马标准。在胸部模型上，所有大于 1 mm 的配准误差均出现在上下轴处，这对于最小的 AP 和 RI 是无法避免的。在骨盆模型上，颅尾误差比胸部小得多，但是，“粗略”的 AP 会出现较大的配准误差，通过“全图像”配准技术，可以将其从 2.90 mm 减少到 0.22 mm。结论 在适应性放射治疗 (ART) 计划中，建议使用 RI 为 6 mm 的“粗略”AP，以提供颅尾更长和更快的 MVCT 扫描，而 应采用“全图像”配准技术以避免较大的残留误差。考虑到 IGRT 和 ART 之间的权衡，在日常实践中强烈建议 AP 为“正常”且 RI 为 2 毫米。
BackgroundTo evaluate the effect of pretreatment megavoltage computed tomographic (MVCT) scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy.MethodsBoth anthropomorphic heterogeneous chest and pelvic phantoms were planned with virtual targets by TomoTherapy Physicist Station and were scanned with TomoTherapy megavoltage image-guided radiotherapy (IGRT) system consisted of six groups of options: three different acquisition pitches (APs) of ‘fine’, ‘normal’ and ‘coarse’ were implemented by multiplying 2 different corresponding reconstruction intervals (RIs). In order to mimic patient setup variations, each phantom was shifted 5 mm away manually in three orthogonal directions respectively. The effect of MVCT scan options was analyzed in image quality (CT number and noise), adaptive dose calculation deviations and positional correction variations.ResultsMVCT scanning time with pitch of ‘fine’ was approximately twice of ‘normal’ and 3 times more than ‘coarse’ setting, all which will not be affected by different RIs. MVCT with different APs delivered almost identical CT numbers and image noise inside 7 selected regions with various densities. DVH curves from adaptive dose calculation with serial MVCT images acquired by varied pitches overlapped together, where as there are no significant difference in allpvalues of intercept & slope of emulational spinal cord (p= 0.761 & 0.277), heart (p= 0.984 & 0.978), lungs (p= 0.992 & 0.980), soft tissue (p= 0.319 & 0.951) and bony structures (p= 0.960 & 0.929) between the most elaborated and the roughest serials of MVCT. Furthermore, gamma index analysis shown that, compared to the dose distribution calculated on MVCT of ‘fine’, only 0.2% or 1.1% of the points analyzed on MVCT of ‘normal’ or ‘coarse’ do not meet the defined gamma criterion. On chest phantom, all registration errors larger than 1 mm appeared at superior-inferior axis, which cannot be avoided with the smallest AP and RI. On pelvic phantom, craniocaudal errors are much smaller than chest, however, AP of ‘coarse’ presents larger registration errors which can be reduced from 2.90 mm to 0.22 mm by registration technique of ‘full image’.ConclusionsAP of ‘coarse’ with RI of 6 mm is recommended in adaptive radiotherapy (ART) planning to provide craniocaudal longer and faster MVCT scan, while registration technique of ‘full image’ should be used to avoid large residual error. Considering the trade-off between IGRT and ART, AP of ‘normal’ with RI of 2 mm was highly recommended in daily practice.
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影响因子：
3.3
作者：
Li, Zhenjiang;Mao, Yu;Li, Baosheng
通讯作者：
Li, Baosheng
DOI：
10.1016/j.ijrobp.2007.04.023
发表时间：
2007-08-01
影响因子：
7
作者：
Chen, Yi-Jen;Han, Chunhui;Wong, Jeffrey Y. C.
通讯作者：
Wong, Jeffrey Y. C.
DOI：
10.6004/jnccn.2013.0084
发表时间：
2013-06-01
影响因子：
13.4
作者：
Ettinger, David S.;Akerley, Wallace;Hughes, Miranda
通讯作者：
Hughes, Miranda
影响因子：
3.8
作者：
Low, DA;Dempsey, JF
通讯作者：
Dempsey, JF
DOI：
10.1016/j.ijrobp.2007.04.094
发表时间：
2008-01-01
影响因子：
7
作者：
Langen, Katja M.;Meeks, Sanford L.;Pouliot, Jean
通讯作者：
Pouliot, Jean