Impact of inhomogeneity corrections on dose coverage in the treatment of lung cancer using stereotactic body radiation therapy
Impact of inhomogeneity corrections on dose coverage in the treatment of lung cancer using stereotactic body radiation therapy
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DOI：
10.1118/1.2745923
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发表时间：
2007-07-01
期刊：
影响因子：
3.8
通讯作者：
Coffey, Charles W.
中科院分区：
文献类型：
--
作者：
Ding, George X.;Duggan, Dennis M.;Coffey, Charles W.
本研究的目的是根据RTOG-0236方案，根据治疗计划评估肺癌患者接受放射治疗时的真实的目标剂量覆盖率。我们比较了更准确的各向异性分析算法（AAA）和笔形射束算法之间的肺癌立体定向体部放射治疗计划的剂量学计算结果。10例非小细胞肺癌患者接受了60戈伊分3次照射，照射野为6 ~ 10 MV，照射野为8-10野。根据肺RTOG-0236方案选择患者。使用无异质性校正的笔形射束算法（PB-NC）进行剂量计算，然后使用相同的射束设置和监测器单元，使用经修改的Pennio异质性校正的笔形射束（PB-MB）和AAA重新计算剂量。在使用PB-NC和AAA之间，计算的95%或99% PTV的剂量差异在处方剂量（60戈伊）的10%以内。然而，与AAA计算的剂量相比，使用PB-MB计算的PTV 95%和99%的最小剂量分别被高估了40%和36%。使用AAA作为参考，使用PB-NC计算的最大剂量被低估了27%，使用PB-MB计算的最大剂量被高估了19%。除PB-NC低估的小的高剂量区外，PB-NC的肺剂量计算与AAA的肺剂量计算基本一致。用AAA计算的界面附近的剂量分布与Monte Carlo计算和测量值一致。本研究表明，真实的最小PTV剂量。当PB-NC用于计算剂量处方中的监测单位设置时，无法保证覆盖范围。(C)2007年美国医学物理学家协会。
The purpose of this study is to assess the real target dose coverage when radiation treatments were delivered to lung cancer patients based on treatment planning according to the RTOG-0236 Protocol. We compare calculated dosimetric results between the more accurate anisotropic analytical algorithm (AAA) and the pencil beam algorithm for stereotactic body radiation therapy treatment planning in lung cancer. Ten patients with non-small cell lung cancer were given 60 Gy in three fractions using 6 and 10 MV beams with 8-10 fields. The patients were chosen in accordance with the lung RTOG-0236 protocol. The dose calculations were performed using the pencil beam algorithm with no heterogeneity corrections (PB-NC) and then recalculated with the pencil beam with modified Batho heterogeneity corrections (PB-MB) and the AAA using an identical beam setup and monitor units. The differences in calculated dose to 95% or 99% of the PTV, between using the PB-NC and the AAA, were within 10% of prescribed dose (60 Gy). However, the minimum dose to 95% and 99% of PTV calculated using the PB-MB were consistently overestimated by up to 40% and 36% of the prescribed dose, respectively, compared to that calculated by the AAA. Using the AAA as reference, the calculated maximum doses were underestimated by up to 27% using the PB-NC and overestimated by 19% using the PB-MB. The calculations of dose to lung from PB-NC generally agree with that of AAA except in the small high-dose region where PB-NC underestimates. The calculated dose distributions near the interface using the AAA agree with those from Monte Carlo calculations as well as measured values. This study indicates that the real minimum PTV dose. coverage cannot be guaranteed when the PB-NC is used to calculate the monitor unit settings in dose prescriptions. (C) 2007 American Association of Physicists in Medicine.