Department of Radiation Oncology, Friedrich-Schiller-University Jena, Bachstrasse 18, D-07743 Jena, Germany.
Radiat Oncol. 2006 Jun 21;1:18. doi: 10.1186/1748-717X-1-18.
To investigate the potential of parotic gland sparing of intensity modulated radiotherapy (3D-c-IMRT) performed with metallic compensators for head and neck cancer in a clinical series by analysis of dose distributions and clinical measures.
39 patients with squamous cell cancer of the head and neck irradiated using 3D-c-IMRT were evaluable for dose distribution within PTVs and at one parotid gland and 38 patients for toxicity analysis. 10 patients were treated primarily, 29 postoperatively, 19 received concomitant cis-platin based chemotherapy, 20 3D-c-IMRT alone. Initially the dose distribution was calculated with Helax and photon fluence was modulated using metallic compensators made of tin-granulate (n = 22). Later the dose distribution was calculated with KonRad and fluence was modified by MCP 96 alloy compensators (n = 17). Gross tumor/tumor bed (PTV 1) was irradiated up to 60-70 Gy, [5 fractions/week, single fraction dose: 2.0-2.2 (simultaneously integrated boost)], adjuvantly irradiated bilateral cervical lymph nodes (PTV 2) with 48-54 Gy [single dose: 1.5-1.8]). Toxicity was scored according the RTOG scale and patient-reported xerostomia questionnaire (XQ).
Mean of the median doses at the parotid glands to be spared was 25.9 (16.3-46.8) Gy, for tin granulate 26 Gy, for MCP alloy 24.2 Gy. Tin-granulate compensators resulted in a median parotid dose above 26 Gy in 10/22, MCP 96 alloy in 0/17 patients. Following acute toxicities were seen (degree 0-2/3): xerostomia: 87%/13%, dysphagia: 84%/16%, mucositis: 89%/11%, dermatitis: 100%/0%. No grade 4 reaction was encountered. During therapy the XQ forms showed (degree 0-2/3): 88%/12%. 6 months postRT chronic xerostomia degree 0-2/3 was observed in 85%/15% of patients, none with degree 4 xerostomia.
3D-c-IMRT using metallic compensators along with inverse calculation algorithm achieves sufficient parotid gland sparing in virtually all advanced head and neck cancers. Since the concept of lower single (and total) doses in the adjuvantly treated volumes reduces acute morbidity 3D-c-IMRT nicely meets demands of concurrent chemotherapy protocols.
通过分析剂量分布和临床指标，研究头颈部癌症调强放疗（3D-c-IMRT）中使用金属补偿器保留腮腺的潜力。
39 例头颈部鳞状细胞癌患者接受 3D-c-IMRT 治疗，对 PTV 内和一侧腮腺的剂量分布进行评估，38 例患者进行毒性分析。10 例患者为初治，29 例为术后治疗，19 例接受顺铂为基础的同期化疗，20 例单独接受 3D-c-IMRT。最初的剂量分布是用 Helax 计算的，并用锡粒制成的金属补偿器（n = 22）调制光子通量。后来，剂量分布是用 KonRad 计算的，并用 MCP 96 合金补偿器（n = 17）修改。大体肿瘤/肿瘤床（PTV1）照射 60-70Gy，[5 个分次/周，单次剂量：2.0-2.2（同时整合增敏）]，辅助照射双侧颈部淋巴结（PTV2）48-54Gy[单次剂量：1.5-1.8]）。毒性根据 RTOG 量表和患者报告的口干问卷（XQ）进行评分。
要保留的腮腺中位数剂量为 25.9（16.3-46.8）Gy，锡粒为 26Gy，MCP 合金为 24.2Gy。22 例患者中有 10 例使用锡粒补偿器的腮腺剂量中位数超过 26Gy，17 例患者中无一例使用 MCP 96 合金补偿器。急性毒性为（0-2/3 级）：口干症：87%/13%，吞咽困难：84%/16%，粘膜炎：89%/11%，皮炎：100%/0%。未发生 4 级反应。在治疗过程中，XQ 表显示（0-2/3 级）：88%/12%。放疗后 6 个月，85%的患者慢性口干症为 0-2/3 级，15%的患者为 4 级口干症。
使用金属补偿器结合逆计算算法的 3D-c-IMRT 实际上可以在所有晚期头颈部癌症中实现足够的腮腺保留。由于辅助治疗体积中较低的单次（和总）剂量的概念降低了急性发病率，因此 3D-c-IMRT 很好地满足了同期化疗方案的要求。
