PDF(Pubmed)
Abstract：
BACKGROUND: The aim of the present study is to examine the impact of kV-CBCT-based online adaptive radiation therapy (ART) on dosimetric parameters in comparison to image-guided-radiotherapy (IGRT) in consecutive patients with tumors in the head and neck region from a prospective registry.
METHODS: The study comprises all consecutive patients with tumors in the head and neck area who were treated with kV-CBCT-based online ART or IGRT-modus at the linear-accelerator ETHOS™. As a measure of effectiveness, the equivalent-uniform-dose was calculated for the CTV (EUDCTV) and organs-at-risk (EUDOAR) and normalized to the prescribed dose. As an important determinant for the need of ART the interfractional shifts of anatomic landmarks related to the tongue were analyzed and compared to the intrafractional shifts. The latter determine the performance of the adapted dose distribution on the verification CBCT2 postadaptation.
RESULTS: Altogether 59 consecutive patients with tumors in the head-and-neck-area were treated from 01.12.2021 to 31.01.2023. Ten of all 59 patients (10/59; 16.9%) received at least one phase within a treatment course with ART. Of 46 fractions in the adaptive mode, irradiation was conducted in 65.2% of fractions with the adaptive-plan, the scheduled-plan in the remaining. The dispersion of the distributions of EUDCTV-values from the 46 dose fractions differed significantly between the scheduled and adaptive plans (Ansari-Bradley-Test, p = 0.0158). Thus, the 2.5th percentile of the EUDCTV-values by the adaptive plans amounted 97.1% (95% CI 96.6-99.5%) and by the scheduled plans 78.1% (95% CI 61.8-88.7%). While the EUDCTV for the accumulated dose distributions stayed above 95% at PTV-margins of ≥ 3 mm for all 8 analyzed treatment phases the scheduled plans did for margins ≥ 5 mm. The intrafractional anatomic shifts of all 8 measured anatomic landmarks were smaller than the interfractional with overall median values of 8.5 mm and 5.5 mm (p < 0.0001 for five and p < 0.05 for all parameters, pairwise comparisons, signed-rank-test). The EUDOAR-values for the larynx and the parotid gland were significantly lower for the adaptive compared with the scheduled plans (Wilcoxon-test, p < 0.001).
CONCLUSIONS: The mobile tongue and tongue base showed considerable interfractional variations. While PTV-margins of 5 mm were sufficient for IGRT, ART showed the potential of decreasing PTV-margins and spare dose to the organs-at-risk.
METHODS: The study comprises all consecutive patients with tumors in the head and neck area who were treated with kV-CBCT-based online ART or IGRT-modus at the linear-accelerator ETHOS™. As a measure of effectiveness, the equivalent-uniform-dose was calculated for the CTV (EUDCTV) and organs-at-risk (EUDOAR) and normalized to the prescribed dose. As an important determinant for the need of ART the interfractional shifts of anatomic landmarks related to the tongue were analyzed and compared to the intrafractional shifts. The latter determine the performance of the adapted dose distribution on the verification CBCT2 postadaptation.
RESULTS: Altogether 59 consecutive patients with tumors in the head-and-neck-area were treated from 01.12.2021 to 31.01.2023. Ten of all 59 patients (10/59; 16.9%) received at least one phase within a treatment course with ART. Of 46 fractions in the adaptive mode, irradiation was conducted in 65.2% of fractions with the adaptive-plan, the scheduled-plan in the remaining. The dispersion of the distributions of EUDCTV-values from the 46 dose fractions differed significantly between the scheduled and adaptive plans (Ansari-Bradley-Test, p = 0.0158). Thus, the 2.5th percentile of the EUDCTV-values by the adaptive plans amounted 97.1% (95% CI 96.6-99.5%) and by the scheduled plans 78.1% (95% CI 61.8-88.7%). While the EUDCTV for the accumulated dose distributions stayed above 95% at PTV-margins of ≥ 3 mm for all 8 analyzed treatment phases the scheduled plans did for margins ≥ 5 mm. The intrafractional anatomic shifts of all 8 measured anatomic landmarks were smaller than the interfractional with overall median values of 8.5 mm and 5.5 mm (p < 0.0001 for five and p < 0.05 for all parameters, pairwise comparisons, signed-rank-test). The EUDOAR-values for the larynx and the parotid gland were significantly lower for the adaptive compared with the scheduled plans (Wilcoxon-test, p < 0.001).
CONCLUSIONS: The mobile tongue and tongue base showed considerable interfractional variations. While PTV-margins of 5 mm were sufficient for IGRT, ART showed the potential of decreasing PTV-margins and spare dose to the organs-at-risk.
摘要：
背景：本研究的目的是研究基于kV-CBCT的在线自适应放射治疗（ART）对剂量参数的影响，与图像引导放射治疗（IGRT）相比来自前瞻性登记的连续头颈部肿瘤患者。
方法：该研究包括所有连续的头颈部肿瘤患者，这些患者接受了基于kV-CBCT的在线ART或线性加速器ETHOS™的IGRT-modus治疗。作为有效性的衡量标准，计算了CTV(EUDCTV)和高危器官(EUDOAR)的等效均匀剂量,并将其标准化至处方剂量.作为需要ART的重要决定因素，分析了与舌头相关的解剖标志的分数间位移，并将其与分数内位移进行了比较。后者确定适应的剂量分布在验证CBCT2后适应上的性能。
结果：从01.12.2021到31.01.2023，共治疗了59例头颈部肿瘤患者。所有59名患者中有10名（10/59;16.9％）在ART治疗过程中至少接受了一个阶段。在自适应模式下的46个分数中，采用自适应计划对65.2%的馏分进行辐照，其余的计划。在计划计划和适应性计划之间，来自46个剂量分数的EUDCTV值分布的分散性显着不同（Ansari-Bradley-Test，p=0.0158)。因此，根据适应性计划,EUDCTV值的第2.5百分位数为97.1%(95%CI96.6-99.5%),根据计划计划为78.1%(95%CI61.8-88.7%).在所有8个分析的治疗阶段中，累积剂量分布的EUDCTV在≥3mm的PTV边缘处保持在95％以上，而计划的计划在≥5mm的边缘处。所有8个测得的解剖标志的显微内解剖位移均小于中间部分，总体中值分别为8.5mm和5.5mm（5个参数的p<0.0001，所有参数的p<0.05，成对比较,符号秩检验)。与计划的计划相比，适应性的喉和腮腺的EUDOAR值显着降低（Wilcoxon检验，p<0.001)。
结论：活动舌和舌根显示出相当大的部分间差异。虽然5毫米的PTV边缘足以用于IGRT，ART显示出降低PTV边缘和危险器官备用剂量的潜力。
方法：该研究包括所有连续的头颈部肿瘤患者，这些患者接受了基于kV-CBCT的在线ART或线性加速器ETHOS™的IGRT-modus治疗。作为有效性的衡量标准，计算了CTV(EUDCTV)和高危器官(EUDOAR)的等效均匀剂量,并将其标准化至处方剂量.作为需要ART的重要决定因素，分析了与舌头相关的解剖标志的分数间位移，并将其与分数内位移进行了比较。后者确定适应的剂量分布在验证CBCT2后适应上的性能。
结果：从01.12.2021到31.01.2023，共治疗了59例头颈部肿瘤患者。所有59名患者中有10名（10/59;16.9％）在ART治疗过程中至少接受了一个阶段。在自适应模式下的46个分数中，采用自适应计划对65.2%的馏分进行辐照，其余的计划。在计划计划和适应性计划之间，来自46个剂量分数的EUDCTV值分布的分散性显着不同（Ansari-Bradley-Test，p=0.0158)。因此，根据适应性计划,EUDCTV值的第2.5百分位数为97.1%(95%CI96.6-99.5%),根据计划计划为78.1%(95%CI61.8-88.7%).在所有8个分析的治疗阶段中，累积剂量分布的EUDCTV在≥3mm的PTV边缘处保持在95％以上，而计划的计划在≥5mm的边缘处。所有8个测得的解剖标志的显微内解剖位移均小于中间部分，总体中值分别为8.5mm和5.5mm（5个参数的p<0.0001，所有参数的p<0.05，成对比较,符号秩检验)。与计划的计划相比，适应性的喉和腮腺的EUDOAR值显着降低（Wilcoxon检验，p<0.001)。
结论：活动舌和舌根显示出相当大的部分间差异。虽然5毫米的PTV边缘足以用于IGRT，ART显示出降低PTV边缘和危险器官备用剂量的潜力。
