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目的 应用三维治疗计划系统 ( 3DTPS)对鼻咽癌常规外照射改进方案进行剂量学研究 ,探讨其临床使用价值。方法 选取初治鼻咽癌患者 8例 ,采用 3DTPS设计照射方案。每例患者均设计 2个方案 :( 1)以鼻前面颈野和双侧面颈联合野为主的常规外照射方案 (改进方案 ) ;( 2 )以双侧面颈联合野为主的常规外照射方案 (传统方案 )。每例患者的 2个方案照射剂量相同。采用剂量体积直方图比较各期鼻咽癌以两种方案照射时靶区、脑干、脊髓、腮腺及颞颌关节的受照体积和剂量。结果 ( 1)改进方案可满足鼻咽和颈部计划靶体积的剂量要求。 ( 2 )两种方案脊髓受照剂量无差异 ;对 5 %和 10 %体积脑干平均受照剂量 (D5、D10 ) ,T1～T3期患者改进方案高于传统方案 (P <0 .0 5 ) ,T4期患者两种方案无差异。 ( 3)改进方案双侧腮腺和颞颌关节受照剂量、分割剂量和被高剂量覆盖的体积均明显低于传统方案 (P <0 .0 1) ,其他正常组织被较高剂量覆盖的体积亦明显小于传统方案 (P <0 .0 1)。结论 与传统方案比较 ,改进方案靶体积在获得满意的剂量覆盖同时 ,可更好地保护腮腺、颞颌关节等正常组织
Objective To evaluate the routine use of 3DTPS in the routine external beam radiation therapy of nasopharyngeal carcinoma and to explore its clinical value. Methods Eight patients with newly diagnosed nasopharyngeal carcinoma were selected and the irradiation program was designed by 3DTPS. Each patient was designed two programs: (1) in front of the nose and bilateral bilateral neck and face field of the conventional conventional external irradiation program (improvement program); (2) to both sides of the neck joint field based conventional External exposure program (traditional program). Each patient’s two programs irradiation dose the same. Dose volume histogram was used to compare the irradiated volume and dose of target, brainstem, spinal cord, parotid gland and temporomandibular joint in each stage of NPC. Results (1) The improved protocol can meet the dose requirements of the planned target volume of the nasopharynx and neck. (2) There was no difference in the dose of spinal cord between the two regimens. The average dose of 5% and 10% brain volume (D5, D10) and T1 to T3 patients were higher than the traditional regimen (P <0.05) ), T4 patients with no difference between the two programs. (3) Improvement program The volume of parotid gland and temporomandibular joint on both sides was significantly lower than that of the traditional scheme (P <0.01) Also significantly less than the traditional program (P <0. 01). Conclusion Compared with the traditional scheme, the target volume of the improved scheme can obtain satisfactory dose coverage and protect the parotid gland, temporomandibular joint and other normal tissues