Comparative analysis of 60Co intensity-modulated radiation therapy.
Comparative analysis of 60Co intensity-modulated radiation therapy.
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60Co调强放射治疗的对比分析。
DOI：
10.1088/0031-9155/53/12/007
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发表时间：
2008
影响因子：
3.5
通讯作者：
Dempsey,JamesF
中科院分区：
文献类型：
--
作者：
Fox,Christopher;Romeijn,HEdwin;Lynch,Bart;Men,Chunhua;Aleman,DionneM;Dempsey,JamesF
在这项研究中，我们进行了科学的比较分析，使用60钴束调强放射治疗（IMRT）。特别是，我们评估了（i）6 MV，18 MV和60 Co IMRT;（ii）不同数量的静态多叶准直器（MLC）提供60 Co射束和（iii）螺旋断层治疗60 Co射束几何形状获得的治疗计划质量。我们采用凸注量图优化（FMO）模型，它允许不同的光束能量和配置之间的计划质量的比较，为给定的情况下。共研究了25例临床患者病例，每个病例均包含体积CT研究、主要和次要勾画目标和轮廓结构：5例头颈部（H&N）、5例前列腺、5例中枢神经系统（CNS）、5例乳腺和5例肺部病例。DICOM计划数据被匿名化并导出至佛罗里达大学优化放射治疗（UFORT）治疗计划系统。对于每个病例，针对H&N、前列腺、CNS和肺病例的5-71个等距射束以及螺旋几何形状，以及针对乳腺病例的上半球中的3-7个等距射束，解决了FMO问题，所有都具有6 MV、18 MV和60 Co剂量模型。在所有情况下，95%的靶体积至少接受了规定剂量，对于未完全或部分包含在靶体积内的所有结构，均符合关键器官的临床保留标准。随着等距60 Co射束数量的增加，发现关键器官保留的改善，但对于H&N、前列腺、CNS和肺，在9个射束以上是边缘性的。乳腺病例产生了3-7束的类似计划。螺旋形60 Co射束几何形状实现了与具有11个等距60 Co射束的静态计划类似的计划质量。此外，最初发现18 MV计划不能提供与6 MV和60 Co计划相同的目标覆盖范围;然而，调整优化模型中的权衡允许18 MV的等效目标覆盖范围。对于具有可比目标覆盖范围的计划，用6 MV射束最好地实现了关键结构保护，紧接着是60 Co射束，18 MV射束需要显著增加对关键结构的剂量。在本文中，我们详细报告了一组代表性的结果，从这些实验。调查结果表明，IMRT放射治疗采用市售的60钴源和双聚焦MLC的潜力。没有观察到增加等距射束的数量超过9个以显著改善目标覆盖或关键器官保留，并且发现静态计划产生与使用相同的良好调整的凸FMO模型优化时使用螺旋断层治疗治疗递送获得的计划相当的计划。虽然先前的研究表明，18 MV计划相当于前列腺调强放疗的6 MV，但我们发现，18 MV射束实际上需要更多的通量来提供类似质量的靶区覆盖。
In this study, we perform a scientific comparative analysis of using 60 Co beams in intensity-modulated radiation therapy (IMRT). In particular, we evaluate the treatment plan quality obtained with (i) 6 MV, 18 MV and 60 Co IMRT;(ii) different numbers of static multileaf collimator (MLC) delivered 60 Co beams and (iii) a helical tomotherapy 60 Co beam geometry. We employ a convex fluence map optimization (FMO) model, which allows for the comparison of plan quality between different beam energies and configurations for a given case. A total of 25 clinical patient cases that each contain volumetric CT studies, primary and secondary delineated targets, and contoured structures were studied: 5 head-and-neck (H&N), 5 prostate, 5 central nervous system (CNS), 5 breast and 5 lung cases. The DICOM plan data were anonymized and exported to the University of Florida optimized radiation therapy (UFORT) treatment planning system. The FMO problem was solved for each case for 5–71 equidistant beams as well as a helical geometry for H&N, prostate, CNS and lung cases, and for 3–7 equidistant beams in the upper hemisphere for breast cases, all with 6 MV, 18 MV and 60 Co dose models. In all cases, 95% of the target volumes received at least the prescribed dose with clinical sparing criteria for critical organs being met for all structures that were not wholly or partially contained within the target volume. Improvements in critical organ sparing were found with an increasing number of equidistant 60 Co beams, yet were marginal above 9 beams for H&N, prostate, CNS and lung. Breast cases produced similar plans for 3–7 beams. A helical 60 Co beam geometry achieved similar plan quality as static plans with 11 equidistant 60 Co beams. Furthermore, 18 MV plans were initially found not to provide the same target coverage as 6 MV and 60 Co plans; however, adjusting the trade-offs in the optimization model allowed equivalent target coverage for 18 MV. For plans with comparable target coverage, critical structure sparing was best achieved with 6 MV beams followed closely by 60 Co beams, with 18 MV beams requiring significantly increased dose to critical structures. In this paper, we report in detail on a representative set of results from these experiments. The results of the investigation demonstrate the potential for IMRT radiotherapy employing commercially available 60 Co sources and a double-focused MLC. Increasing the number of equidistant beams beyond 9 was not observed to significantly improve target coverage or critical organ sparing and static plans were found to produce comparable plans to those obtained using a helical tomotherapy treatment delivery when optimized using the same well-tuned convex FMO model. While previous studies have shown that 18 MV plans are equivalent to 6 MV for prostate IMRT, we found that the 18 MV beams actually required more fluence to provide similar quality target coverage.
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