Dosimetric benefits of respiratory gating: a preliminary study.
Dosimetric benefits of respiratory gating: a preliminary study.
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DOI：
10.1120/jacmp.26.146
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发表时间：
2004-01-01
影响因子：
2.1
通讯作者：
Starkschall, George
中科院分区：
文献类型：
--
作者：
Butler, Laura E;Forster, Kenneth M;Starkschall, George
在这项研究中，我们比较了呼气期间施加呼吸门控时受到照射的肺组织量与吸气期间施加门控时受到照射的肺组织量。我们的假设是，随着吸气的增加，幸存的肺组织数量也会增加。获取了 10 名被诊断患有原发性支气管癌的患者的计算机断层扫描 (CT) 图像数据集。数据集是在自由呼吸和屏气期间以 0% 潮气量和 100% 潮气量获取的，如果可能的话，在深吸气时获取，对应于大约 60% 的肺活量。根据每个门控数据集制定了两种治疗计划：一种是自由呼吸计划的治疗门户，另一种是基于门控计划目标量的治疗门户。将 0% 潮气量时计算的肺部剂量质量直方图与深吸气和 100% 潮气量时计算的剂量质量直方图进行比较。从剂量-质量直方图中提取的数据用于确定最有剂量学优势的门控点、门控导致的受辐射肺组织数量的减少以及可能预测门控更大需求的任何疾病特征。数据显示，当使用基于门控计划目标体积的治疗端口时，受照射的正常组织质量减少。对于所有患者来说，深吸气时比其他两个门控点保留更多的正常肺组织，但在呼吸周期的每个点都保留正常肺组织。未发现不同疾病特征的照射组织数量存在显着差异。胸部放射治疗的呼吸门控通常可以提高治疗计划的质量，但在执行实际治疗计划之前可能无法确定哪些患者可以从门控中受益。
In this study, we compared the amount of lung tissue irradiated when respiratory gating was imposed during expiration with the amount of lung tissue irradiated when gating was imposed during inspiration. Our hypothesis was that the amount of lung tissue spared increased as inspiration increased. Computed tomography (CT) image data sets were acquired for 10 patients who had been diagnosed with primary bronchogenic carcinoma. Data sets were acquired during free breathing and during breath-holds at 0% tidal volume and 100% tidal volume, and, when possible, at deep inspiration, corresponding to approximately 60% vital capacity. Two treatment plans were developed on the basis of each of the gated data sets: one in which the treatment portals were those of the free-breathing plan, and the other in which the treatment portals were based on the gated planning target volumes. Dose-mass histograms of the lungs calculated at 0% tidal volume were compared to those calculated at deep inspiration and at 100% tidal volume. Data extracted from the dose-mass histograms were used to determine the most dosimetrically beneficial point to gate, the reduction in the amount of irradiated lung tissue that resulted from gating, and any disease characteristics that might predict a greater need for gating. The data showed a reduction in the mass of normal tissue irradiated when treatment portals based on the gated planning target volume were used. More normal lung tissue was spared at deep inspiration than at the other two gating points for all patients, but normal lung tissue was spared at every point in the respiratory cycle. No significant differences in the amount of irradiated tissue by disease characteristic were identified. Respiratory gating of thoracic radiation treatments can often improve the quality of the treatment plan, but it may not be possible to determine which patients may benefit from gating prior to performing the actual treatment planning.