目的 深呼吸屏气（DIBH）放疗期间相较于自由呼吸治疗可能减少对肺部和心脏的辐射剂量。然而，多次呼吸屏气之间的靶移可能会降低靶区的覆盖度。我们将规划CT（CTDIBH3）和呼吸屏气治疗前后测量的CBCT扫描之间的靶移进行了比较。 材料与方法 共收治了29名肺癌患者和9名淋巴瘤患者进行了DIBH治疗。使用外部闸门模块作为DIBH水平的替代品，它具有2mm的窗口宽度。获取了四个DIBH CT扫描：一个用于规划（CTDIBH3），还有三个额外的扫描（CTDIBH1,2,4）用于通过与CTDIBH3的配准来评估扫描时的呼吸屏气内靶移。治疗期间，进行了治疗前（CBCTpre）和治疗后（CBCTpost）扫描。对于每对CBCTpre/post，确定了靶在呼吸屏气内的转移。对于肺癌，肿瘤（GTV-Tlung）和淋巴结（GTV-Nlung）分别进行了分析。计算了组平均（GM），系统误差和随机误差以及绝对最大移位（GMmax）的GM，用于CTDIBH1,2,3,4之间和CBCTpre/post之间的移位。 结果 对于GTV-Tlung，CBCT的GMmax在所有方向上均大于CT。上下方向的GMmax分别为3.3mm（CT）和6.1mm（CBCT）。在左右和上下方向上的偏移标准差在CBCT上大于CT。对于GTV-Nlung和CTVlymphoma，GMmax或SD没有发现差异。 结论 规划CT会小于治疗期间CBCTpre/post观察到的呼吸屏气内转移，因此低估了治疗期间的呼吸屏气内靶移不确定性。肺肿瘤的治疗期间内变异比淋巴结和淋巴瘤靶区更大。版权所有©2023 Elsevier B.V. 保留所有权利。

/objective Deep-inspiration breath-hold (DIBH) during radiotherapy may reduce dose to the lungs and heart compared to treatment in free breathing. However, intra-fractional target shifts between several breath-holds may decrease target coverage. We compared target shifts between four DIBHs at the planning-CT session with those measured on CBCT-scans obtained pre- and post-DIBH treatments. Material/methods Twenty-nine lung cancer and nine lymphoma patients were treated in DIBH. An external gating block was used as surrogate for the DIBH-level with a window of 2mm. Four DIBH CT-scans were acquired: one for planning (CTDIBH3) and three additional (CTDIBH1,2,4) to assess the intra-DIBH target shifts at scanning by registration to CTDIBH3. During treatment, pre-treatment (CBCTpre) and post-treatment (CBCTpost) scans were acquired. For each pair of CBCTpre/post, the target intra-DIBH shift was determined. For lung cancer, tumour (GTV-Tlung) and lymph nodes (GTV-Nlung) were analysed separately. Group mean (GM), systematic and random errors, and GM for the absolute maximum shifts (GMmax) were calculated for the shifts between CTDIBH1,2,3,4 and between CBCTpre/post. Results For GTV-Tlung, GMmax was larger at CBCT than CT in all directions. GMmax in cranio-caudal direction was 3.3mm (CT)and 6.1mm (CBCT). The standard deviations of the shifts in the left-right and cranio-caudal directions were larger at CBCT than CT. For GTV-Nlung and CTVlymphoma, no difference was found in GMmax or SD. Conclusion Intra-DIBH shifts at planning-CT session are generally smaller than intra-DIBH shifts observed at CBCTpre/post and therefore underestimate the intra-fractional DIBH uncertainty during treatment. Lung tumours show larger intra-fractional variations than lymph nodes and lymphoma targets.Copyright © 2023 Elsevier B.V. All rights reserved.