Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Phys Med Biol. 2010 Jan 21;55(2):403-16. doi: 10.1088/0031-9155/55/2/005. Epub 2009 Dec 17.
Macroaggregated albumin single-photon emission computed tomography (MAA-SPECT) provides a map of the spatial distribution of lung perfusion. Our previous work developed a methodology to use SPECT guidance to reduce the dose to the functional lung in IMRT planning. This study aims to investigate the role of beam arrangement on both low and high doses in the functional lung. In our previous work, nine-beam IMRT plans were generated with and without SPECT guidance and compared for five patients. For the current study, the dose-function histogram (DFH) contribution for each of the nine beams for each patient was calculated. Four beams were chosen based on orientation and DFH contributions to create a SPECT-guided plan that spared the functional lung and maintained target coverage. Four-beam SPECT-guided IMRT plans reduced the F(20) and F(30) values by (16.5 +/- 6.8)% and (6.1 +/- 9.2)%, respectively, when compared to nine-beam conventional IMRT plans. Moreover, the SPECT-4F Plan reduces F(5) and F(13) for all patients by (11.0 +/- 8.2)% and (6.1 +/- 3.6)%, respectively, compared to the SPECT Plan. Using fewer beams in IMRT planning may reduce the amount of functional lung that receives 5 and 13 Gy, a factor that has recently been associated with radiation pneumonitis.
单光子发射计算机断层扫描（MAA-SPECT）可提供肺部灌注的空间分布图谱。我们之前的工作开发了一种使用 SPECT 指导来减少调强放疗计划中功能性肺剂量的方法。本研究旨在探讨在低剂量和高剂量下，射束排列在功能性肺中的作用。在我们之前的工作中，对 5 名患者生成了有和没有 SPECT 指导的九射束调强放疗计划，并进行了比较。对于当前的研究，为每位患者计算了每个九束射束的剂量-功能直方图（DFH）贡献。根据方向和 DFH 贡献选择了四束射束来创建 SPECT 引导的计划，以保护功能性肺并保持靶区覆盖。与九射束常规调强放疗计划相比，四射束 SPECT 引导调强放疗计划可分别降低 F(20)和 F(30)值（16.5±6.8）%和（6.1±9.2）%。此外，与 SPECT 计划相比，SPECT-4F 计划可使所有患者的 F(5)和 F(13)值分别降低（11.0±8.2）%和（6.1±3.6）%。在调强放疗计划中使用较少的射束可能会减少接受 5 和 13 Gy 的功能性肺量，这一因素最近与放射性肺炎有关。
