Background: Patients bearing large-volume, bulky primary or relapsed tumors, are usually referred to palliative low-dose radiotherapy with very poor results. Lattice Radiation Therapy (LRT) is able to produce a high number of high-dose foci or vortexes (multiple SBRT treatments), separated by low-dose zones (valleys). Treatment planning on vortex placing, valley definition, and dose administered depends on individual decisions of the treating team. The aim of our study is to assess for the first time the possibility of a dense fractionated LRT within the target volume. Methods: A total of 22 treatments in 20 patients were performed in the frame of a prospective observational study of fractionated LRT ongoing in our institution. According to our aim of achieving dense LRT, no GTV contraction was considered to create the LRTV (GTV is equal to LRTV). The vortexes were segmented as 1 cm diameter at a 1.5 cm vortex-to-vortex distance. Dose prescription to the vortexes per fraction was 12 Gy. Results: The vortex/LRTV ratio was 7.38 ± 2.13% (3.4–10.40%, median 7.60%). Mean dose to the vortex volume was 11.90 ± 0.09 Gy (11.70–12.10 Gy, median 11.90 Gy). Mean dose administered to the valley volume was 8.29 ± 0.70 (7.05–9.51 Gy, median 8.29 Gy). Valley/vortex (peak) dose ratio (VPDR) was 69.40 ± 6.02% (59.00–79.80%, median 69.70%). The mean peripheral tumor dose was 5.11 ± 0.8710 Gy (3.16–6.78 Gy, median 5.18 Gy). Conclusions: Our dense LRT schedule fulfilled most of the recommended guidelines for LRT, increasing the high dose points without risking the dose to the surrounding tissues. Further analysis of feasibility and safety are needed to secure the clinical relevance of our proposed protocol.
背景：对于体积庞大、原发或复发的肿瘤患者，通常采用姑息性低剂量放疗，但疗效甚微。格点放射治疗（LRT）能够在肿瘤内部产生大量高剂量聚焦点或涡旋区（相当于多次立体定向放射治疗），这些高剂量区域之间由低剂量区（谷区）分隔。治疗计划中涡旋区的布设、谷区的界定以及剂量施予均依赖于治疗团队的个体化决策。本研究首次旨在评估在靶区内实施密集分次LRT的可行性。 方法：在本机构进行的一项前瞻性观察性分次LRT研究中，共对20名患者实施了22次治疗。为实现密集LRT的目标，我们在创建LRT靶区（LRTV）时未考虑对大体肿瘤体积（GTV）进行收缩（即GTV等同于LRTV）。涡旋区被设定为直径1厘米，涡旋中心间距为1.5厘米。每个分次中涡旋区的处方剂量为12 Gy。 结果：涡旋区体积与LRTV体积之比为7.38 ± 2.13%（范围3.4–10.40%，中位数7.60%）。涡旋区的平均剂量为11.90 ± 0.09 Gy（范围11.70–12.10 Gy，中位数11.90 Gy）。谷区的平均施予剂量为8.29 ± 0.70 Gy（范围7.05–9.51 Gy，中位数8.29 Gy）。谷区与涡旋区（峰值）剂量比（VPDR）为69.40 ± 6.02%（范围59.00–79.80%，中位数69.70%）。肿瘤外周的平均剂量为5.11 ± 0.87 Gy（范围3.16–6.78 Gy，中位数5.18 Gy）。 结论：我们设计的密集LRT方案符合LRT的大部分推荐指南，在增加高剂量点的同时并未增加周围组织的受照风险。为确保我们提出的方案具有临床相关性，尚需对其可行性和安全性进行进一步分析。
Automated Clinical Dosimetry Planning of Dense Lattice Radiation Therapy
肿瘤(癌症)患者之家