BACKGROUND Breast intraoperative electron radiation therapy (B-IOERT) can be used in clinical practice both as elective irradiation (partial breast irradiation - APBI) in low risk breast cancer patients, and as an anticipated boost. The procedure generally includes the use of a shielding disk between the residual breast and the pectoralis fascia for the protection of the tissues underneath the target volume. The aim of the study was to evaluate the role of intraoperative ultrasound (IOUS) in improving the quality of B-IOERT. PATIENTS AND METHODS B-IOERT was introduced in Trieste in 2012 and its technique was improved in 2014 with IOUS. Both, needle and IOUS were used to measure target thickness and the latter was used even to check the correct position of the shielding disk. The primary endpoint of the study was the evaluation of the effectiveness of IOUS in reducing the risk of a disk misalignment related to B-IOERT and the secondary endpoint was the analysis of acute and late toxicity, by comparing two groups of patients treated with IOERT as a boost, either measured with IOUS and needle (Group 1) or with needle alone (Group 2). Acute and late toxicity were evaluated by validated scoring systems. RESULTS From the institutional patients who were treated between June 2012 and October 2019, 109 were eligible for this study (corresponding to 110 cases, as one patients underwent bilateral conservative surgery and bilateral B-IOERT). Of these, 38 were allocated to group 1 and 72 to group 2. The target thickness measured with the IOUS probe and with the needle were similar (mean difference of 0.1 mm, p = 0.38). The percentage of patients in which the shield was perfectly aligned after IOUS introduction increased from 23% to more than 70%. Moreover, patients treated after IOUS guidance had less acute toxicity (36.8% vs. 48.6%, p = 0.33) from radiation therapy, which reached no statistical significance. Late toxicity turned out to be similar regardless of the use of IOUS guidance: 39.5% vs. 37.5% (p = 0.99). CONCLUSIONS IOUS showed to be accurate in measuring the target depth and decrease the misalignment between collimator and disk. Furthermore there was an absolute decrease in acute toxicity, even though not statistically significant, in the group of women who underwent B-IOERT with IOUS guidance.

中文翻译：

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术中超声引入后乳房术中电子放射治疗的最新技术。

背景技术乳房术中电子放射治疗 (B-IOERT) 可在临床实践中用作低风险乳腺癌患者的选择性照射（部分乳房照射 - APBI），以及预期的增强。该程序通常包括在残留乳房和胸肌筋膜之间使用屏蔽盘，以保护目标体积下方的组织。该研究的目的是评估术中超声 (IOUS) 在提高 B-IOERT 质量中的作用。患者和方法 B-IOERT 于 2012 年在的里雅斯特引入，其技术在 2014 年通过 IOUS 得到改进。针和 IOUS 都用于测量目标厚度，后者甚至用于检查屏蔽盘的正确位置。该研究的主要终点是评估 IOUS 在降低与 B-IOERT 相关的椎间盘错位风险方面的有效性，次要终点是分析急性和晚期毒性，通过比较接受 IOERT 治疗的两组患者增强，用 IOUS 和针（第 1 组）或单独用针（第 2 组）测量。通过经过验证的评分系统评估急性和晚期毒性。结果 在 2012 年 6 月至 2019 年 10 月期间接受治疗的机构患者中，有 109 人符合本研究的条件（对应 110 例，其中一名患者接受了双侧保守手术和双侧 B-IOERT）。其中，38 人分配到第 1 组，72 人分配到第 2 组。用 IOUS 探头和针测量的目标厚度相似（平均差异为 0.1 毫米，p = 0.38）。引入 IOUS 后盾牌完全对齐的患者百分比从 23% 增加到 70% 以上。此外，在 IOUS 指导下接受治疗的患者放疗的急性毒性较低（36.8% 对 48.6%，p = 0.33），没有达到统计学意义。无论使用 IOUS 指导如何，晚期毒性结果都是相似的：39.5% 对 37.5% (p = 0.99)。结论 IOUS 表明在测量目标深度方面是准确的，并减少了准直器和圆盘之间的未对准。此外，在接受 IOUS 指导下的 B-IOERT 的女性组中，急性毒性绝对下降，尽管没有统计学意义。在 IOUS 指导下接受治疗的患者放疗的急性毒性较低（36.8% 对 48.6%，p = 0.33），没有统计学意义。无论使用 IOUS 指导如何，晚期毒性结果都是相似的：39.5% 对 37.5% (p = 0.99)。结论 IOUS 表明在测量目标深度方面是准确的，并减少了准直器和圆盘之间的未对准。此外，在接受 IOUS 指导下的 B-IOERT 的女性组中，急性毒性绝对下降，尽管没有统计学意义。在 IOUS 指导下接受治疗的患者放疗的急性毒性较低（36.8% 对 48.6%，p = 0.33），没有统计学意义。无论使用 IOUS 指导如何，晚期毒性结果都是相似的：39.5% 对 37.5% (p = 0.99)。结论 IOUS 表明在测量目标深度方面是准确的，并减少了准直器和圆盘之间的未对准。此外，在接受 IOUS 指导下的 B-IOERT 的女性组中，急性毒性绝对下降，尽管没有统计学意义。结论 IOUS 表明在测量目标深度方面是准确的，并减少了准直器和圆盘之间的未对准。此外，在接受 IOUS 指导下的 B-IOERT 的女性组中，急性毒性绝对下降，尽管没有统计学意义。结论 IOUS 表明在测量目标深度方面是准确的，并减少了准直器和圆盘之间的未对准。此外，在接受 IOUS 指导下的 B-IOERT 的女性组中，急性毒性绝对下降，尽管没有统计学意义。