A method for the reconstruction of four-dimensional synchronized CT scans acquired during free breathing
A method for the reconstruction of four-dimensional synchronized CT scans acquired during free breathing
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DOI：
10.1118/1.1576230
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发表时间：
2003-06-01
期刊：
影响因子：
3.8
通讯作者：
Whiting, BR
中科院分区：
文献类型：
--
作者：
Low, DA;Nystrom, M;Whiting, BR
呼吸运动是胸部和上腹部放射治疗计划中的一个重要误差来源。考虑呼吸运动对这些部位采用的适形放射射野的大小有着深远的影响。呼吸运动还导致在自由呼吸期间采集的治疗计划计算机断层扫描（CT）扫描中的伪影和失真，并且还导致强度调制放射治疗中放射射野叠加假设的崩溃，可能导致显著的剂量输送误差。提出的自愿和非自愿屏气技术具有减少或消除呼吸运动影响的潜力，然而，它们在实践中受到限制，因为许多肺癌患者不能耐受屏气。我们提出了一种替代解决方案，以占呼吸运动在放射治疗计划，多层CT扫描同时收集与数字肺功能测定在许多自由呼吸周期，以创建一个四维（4-D）的图像集，其中潮气肺容量是额外的维度。该4-D数据的分析导致用于数字肺量计的方法，基于消除或计算自由呼吸患者的放射治疗计划中的呼吸运动伪影。4-D图像集是通过根据用户定义的潮气量箱对自由呼吸多层螺旋CT扫描进行排序而生成的。多层螺旋CT扫描仪在电影模式下操作，每个治疗床位置采集15次扫描，同时患者接受数字肺量计测量。肺活量测定法用于通过患者正常呼吸周期内的相关潮气肺容量对CT扫描进行回顾性分类。该方法已使用来自三名肺癌患者的数据进行了原型化。实际潮气肺容量与规定的箱容量一致，标准差范围为22至33 cm 3。矢状面和冠状面图像的分析显示相对较小（
Breathing motion is a significant source of error in radiotherapy treatment planning for the thorax and upper abdomen. Accounting for breathing motion has a profound effect on the size of conformal radiation portals employed in these sites. Breathing motion also causes artifacts and distortions in treatment planning computed tomography (CT) scans acquired during free breathing and also causes a breakdown of the assumption of the superposition of radiation portals in intensity-modulated radiation therapy, possibly leading to significant dose delivery errors. Proposed voluntary and involuntary breath-hold techniques have the potential for reducing or eliminating the effects of breathing motion, however, they are limited in practice, by the fact that many lung cancer patients cannot tolerate holding their breath. We present an alternative solution to accounting for breathing motion in radiotherapy treatment planning, where multislice CT scans are collected simultaneously with digital spirometry over many free breathing cycles to create a four-dimensional (4-D) image set, where tidal lung volume is the additional dimension. An analysis of this 4-D data leads to methods for digital-spirometry, based elimination or accounting of breathing motion artifacts in radiotherapy treatment planning for free breathing patients. The 4-D image set is generated by sorting free-breathing multislice CT scans according to user-defined tidal-volume bins. A multislice CT scanner is operated in the cine mode, acquiring 15 scans per couch position, while the patient undergoes simultaneous digital-spirometry measurements. The spirometry is used to retrospectively sort the CT scans by their correlated tidal lung volume within the patient's normal breathing cycle. This method has been prototyped using data from three lung cancer patients. The actual tidal lung volumes agreed with the specified bin volumes within standard deviations ranging between 22 and 33 cm 3. An analysis of sagittal and coronal images demonstrated relatively small (