Influence of intra-fractional breathing movement in step-and-shoot IMRT
Influence of intra-fractional breathing movement in step-and-shoot IMRT
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DOI：
10.1088/0031-9155/49/12/n03
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发表时间：
2004-06-21
影响因子：
3.5
通讯作者：
Debus, J
中科院分区：
文献类型：
--
作者：
Schaefer, M;M端nter, MW;Debus, J
已经努力将调强放射治疗的应用扩展到各种器官。其中一个悬而未决的问题是，呼吸诱导的器官运动是否会导致相关的过量或不足剂量，例如，在肺癌放射治疗计划中。关于不同类型的调强放射治疗，人们已经进行了理论上的考虑，但仍然缺乏实验数据。我们用一个新的体模和九个电离室检查了一个非小细胞肺癌临床治疗计划的一小部分中的18个点。以每分钟12和16个呼吸周期的速度进行测量。运动12周(-1)时，静止点与运动靶点之间的剂量差为-2.4%~+5.5%(平均值：+0.2%，中位数：-0.1%)；运动16周期(-1)时，静止点与运动靶点之间的剂量差为-3.6%~+5.0%(平均值：-0.4%，中位数：-0.6%)。除了一个例外，在有和没有运动的情况下，所有测量的差异都在5%以下。总之，我们的结果强调，至少在静态调强放射治疗中，由于准直器叶片运动和靶运动之间的相互作用而产生的呼吸效应(与靶区剂量覆盖有关)是次要的，并且不会降低调强放疗在胸部靶区步进式照射技术中的临床价值。
Efforts have been made to extend the application of intensity-modulated radiotherapy to a variety of organs. One of the unanswered questions is whether breathing-induced organ motion may lead to a relevant over-or underdosage, e.g., in treatment plans for the irradiation of lung cancer. Theoretical considerations have been made concerning the different kinds of IMRT but there is still a lack of experimental data. We examined 18 points in a fraction of a clinical treatment plan of a NSCLC delivered in static IMRT with a new phantom and nine ionization chambers. Measurements were performed at a speed of 12 and 16 breathing cycles per minute. The dose differences between static points and moving target points ranged between -2.4% and +5.5% (mean: +0.2%, median: -0.1%) when moving with 12 cycles min(-1) and between -3.6% and +5.0% (mean: -0.4%, median: -0.6%) when moving with 16 cycles min(-1). All differences of measurements with and without movements were below 5%, with one exception. In conclusion, our results underline that at least in static IMRT breathing effects (concerning target dose coverage) due to interplay effects between collimator leaf movement and target movement are of secondary importance and will not reduce the clinical value of IMRT in the step-and-shoot technique for irradiation of thoracic targets.