Wust Peter, Beck Marcus, Dabrowski Robert, Neumann Oliver, Zschaeck Sebastian, Kaul David, Modest Dominik P, Stromberger Carmen, Gebauer Bernhard, Ghadjar Pirus
Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Radiation Oncology, Augustenburger Platz 1, 13353, Berlin, Germany.
Berlin Institute of Health (BIH), Anna-Louisa-Karsch-Straße 2, 10178, Berlin, Germany.
Radiat Oncol. 2021 Mar 16;16(1):51. doi: 10.1186/s13014-021-01779-5.
Several radiotherapeutic approaches for patients with oligotopic malignant liver lesions unfit for surgical resection exist. The most advanced competitive techniques are high-dose-rate (HDR) brachytherapy, Cyberknife, volume-modulated-arc therapy (VMAT) and Tomotherapy. We evaluated the optimal technique by a planning study for a single ablative dose with different lesion sizes.
We compared dose distributions of HDR-brachytherapy with stereotactic ablative radiotherapy using the Cyberknife, VMAT or Tomotherapy. Tumor-control-probabilities (TCP), normal-tissue-complication-probabilities (NTCP) were determined in a theoretical framework applying a single dose of 20 Gy (demanding 95% coverage) for intrahepatic lesions of 1-5 cm in size. We evaluated therapeutic ratios by TCP (mean dose in the lesion) relative to high-dose (conformality) or low-dose liver exposition in dependency on the lesion size for each technique. In addition, we considered treatment times and accuracy (clinical target volume vs planning target volume).
HDR-brachtherapy has the highest therapeutic ratios with respect to high-dose as well as low-dose liver exposition even for extended lesions, and the Cyberknife being suited second best. However, for lesions ≥ 3 cm diameter the therapeutic ratios of all ablative techniques are increasingly converging, and better tolerance and shorter treatment times of noninvasive external techniques become more important. On the other hand, mean tumor doses of HDR-brachytherapy of near 60 Gy are unattainable by the other techniques gaining only 22-34 Gy, and the conformality of HDR-brachytherapy is still rather good for lesions ≥ 3 cm diameter.
HDR-brachytherapy is by far the most effective technique to treat intrahepatic lesions by a single fraction, but sparing of the surroundings declines with increasing lesion size and approaches the benchmarks of external beam radiosurgery techniques. External beam radiotherapy has the advantage to use suitable fractionation schedules.
对于不适合手术切除的寡灶性恶性肝损伤患者，存在多种放射治疗方法。最先进的竞争技术是高剂量率（HDR）近距离放射治疗、射波刀、容积调强弧形放疗（VMAT）和断层放射治疗。我们通过一项针对不同病变大小的单次消融剂量的计划研究来评估最佳技术。
我们比较了HDR近距离放射治疗与使用射波刀、VMAT或断层放射治疗的立体定向消融放疗的剂量分布。在理论框架内，对于大小为1 - 5厘米的肝内病变，应用20 Gy的单次剂量（要求95%的覆盖范围）来确定肿瘤控制概率（TCP）和正常组织并发症概率（NTCP）。我们通过TCP（病变中的平均剂量）相对于高剂量（适形性）或低剂量肝脏照射来评估每种技术在不同病变大小下的治疗比。此外，我们还考虑了治疗时间和准确性（临床靶体积与计划靶体积）。
即使对于较大的病变，HDR近距离放射治疗在高剂量和低剂量肝脏照射方面都具有最高的治疗比，射波刀次之。然而，对于直径≥3厘米的病变，所有消融技术的治疗比越来越接近，非侵入性外部技术更好的耐受性和更短的治疗时间变得更加重要。另一方面，其他技术无法达到HDR近距离放射治疗接近60 Gy的平均肿瘤剂量，只能达到22 - 34 Gy，并且对于直径≥3厘米的病变，HDR近距离放射治疗的适形性仍然相当好。
HDR近距离放射治疗是迄今为止单次分割治疗肝内病变最有效的技术，但随着病变大小增加，对周围组织的保护作用下降，并接近外照射放射外科技术的基准。外照射放疗具有使用合适分割方案的优势。
