BACKGROUND The aim of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation (APBI) especially concerning the dose of organs at risk (OAR-s). PATIENTS AND METHODS Treatment plans of thirty-two MIBT and CK patients were compared. The OAR-s included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left-sided cases. The fractionation was identical (4 x 6.25 Gy) in both treatment groups. The relative volumes (e.g. V100, V90) receiving a given relative dose (100%, 90%), and the relative doses (e.g. D0.1cm3, D1cm3) delivered to the most exposed small volumes (0.1 cm3, 1 cm3) were calculated from dose-volume histograms. All dose values were related to the prescribed dose (25 Gy). RESULTS Regarding non-target breast CK performed slightly better than MIBT (V100: 0.7% vs. 1.6%, V50: 10.5% vs. 12.9%). The mean dose of the ipsilateral lung was the same for both techniques (4.9%), but doses irradiated to volume of 1 cm3 were lower with MIBT (36.1% vs. 45.4%). Protection of skin and rib was better with MIBT. There were no significant differences between the dose-volume parameters of the heart, but with MIBT, slightly larger volumes were irradiated by 5% dose (V5: 29.9% vs. 21.2%). Contralateral breast and lung received a somewhat higher dose with MIBT (D1cm3: 2.6% vs. 1.8% and 3.6% vs. 2.5%). CONCLUSIONS The target volume can be properly irradiated by both techniques with similar dose distributions and high dose conformity. Regarding the dose to the non-target breast, heart, and contralateral organs the CK was superior, but the nearby organs (skin, ribs, ipsilateral lung) received less dose with MIBT. The observed dosimetric differences were small but significant in a few parameters at the examined patient number. More studies are needed to explore whether these dosimetric findings have clinical significance.

中文翻译：

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多导管间质近距离放射治疗与使用射波刀的立体定向放射治疗加速部分乳房照射：一项关于风险器官剂量测定的比较治疗计划研究。

背景本研究的目的是在剂量学上比较多导管间质近距离放射治疗 (MIBT) 和使用射波刀 (CK) 的立体定向放射治疗对加速部分乳房照射 (APBI) 尤其是风险器官 (OAR-s) 的剂量。患者和方法 比较了 32 名 MIBT 和 CK 患者的治疗计划。OAR-s 包括同侧非目标和对侧乳房、同侧和对侧肺、皮肤、肋骨和左侧病例的心脏。两个治疗组的分割是相同的（4 x 6.25 Gy）。计算接受给定相对剂量（100%、90%）的相对体积（例如 V100、V90），以及递送至暴露最多的小体积（0.1 cm3、1 cm3）的相对剂量（例如 D0.1cm3、D1cm3）从剂量体积直方图。所有剂量值均与规定剂量 (25 Gy) 相关。结果 关于非目标乳房 CK 的表现略好于 MIBT（V100：0.7% 对 1.6%，V50：10.5% 对 12.9%）。两种技术的同侧肺的平均剂量相同 (4.9%)，但 MIBT 照射到体积为 1 cm3 的剂量较低（36.1% 对 45.4%）。MIBT对皮肤和肋骨的保护更好。心脏的剂量-体积参数之间没有显着差异，但对于 MIBT，5% 剂量照射稍大的体积（V5：29.9% 与 21.2%）。对侧乳房和肺接受 MIBT 的剂量稍高（D1cm3：2.6% 对 1.8% 和 3.6% 对 2.5%）。结论 两种具有相似剂量分布和高剂量一致性的技术都可以正确照射靶区。关于非目标乳房的剂量，在心脏和对侧器官中，CK 更优，但附近器官（皮肤、肋骨、同侧肺）接受的 MIBT 剂量较少。观察到的剂量学差异很小，但在检查的患者数量的几个参数中是显着的。需要更多的研究来探索这些剂量测定结果是否具有临床意义。