中华放射医学与防护杂志

吴伟伟,李韶今,尹慧,肖应,刘历鹏.局部晚期鼻咽癌调强放疗中解剖结构改变及剂量分布变化研究[J].中华放射医学与防护杂志,2017,37(11):826-831

局部晚期鼻咽癌调强放疗中解剖结构改变及剂量分布变化研究

Anatomical changes and dose distribution deviations of locally advanced nasopharyngeal carcinoma patients during IMRT

投稿时间：2017-01-05 修订日期：2017-01-05

DOI：10.3760/cma.j.issn.0254-5098.2017.11.005

中文关键词: 鼻咽癌调强放疗锥形束CT 二程计划

英文关键词:Nasopharyngeal carcinoma Intensity modulated radiation therapy Cone beam CT (CBCT) Replanning

基金项目:江西省科技厅计划项目（20142BBG70109）

作者	单位
吴伟伟	341000 赣州市肿瘤医院放疗科
李韶今	341000 赣州市肿瘤医院放疗科
尹慧	341000 赣州市肿瘤医院放疗科
肖应	341000 赣州市肿瘤医院放疗科
刘历鹏	341000 赣州市肿瘤医院放疗科

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中文摘要:

目的探讨局部晚期鼻咽癌患者在调强放疗（IMRT）期间的解剖结构体积改变及剂量分布变化。方法选取18例局部晚期鼻咽癌患者，利用每周锥形束CT （CBCT）分析患者的解剖结构体积变化，并在放疗20次后再次进行IMRT计划设计，探讨二程IMRT计划的剂量学。结果 GTV_nx每周平均缩小3.15%，共缩小22.03%；GTV_nd每周平均缩小5.67%，共缩小39.68%；左右腮腺每周分别缩小4.93%和5.26%，总共缩小29.60%和31.56%。GTV_nd和腮腺在放疗前4周有较大退缩，放疗4周后体积改变趋于平缓。与初始Plan 1相比，Plan 2中PGTV_nd的D₉₅下降2.20%（t=2.382，P<0.05），而PGTV_nx、PTV₁和PTV₂的D₉₅没有显著变化；左腮腺D_mean、D₅₀和V₃₀分别增加7.34%、12.68%和10.90%，与放疗前比较差异均有统计学意义（t=-3.376、-3.738、-3.679，P<0.05）；右腮腺D_mean、D₅₀和V₃₀分别增加6.13%、11.17%和9.72%，与放疗前比较差异均有统计学意义（t=-2.550、-2.446、-2.673，P<0.05）；喉的D_mean平均增加8.69%，与放疗前比较差异均有统计学意义（t=-3.099，P<0.05）。相比较于Plan 2，综合计划Plan （1+2）中PGTV_nd的D₉₅增加1.37%，差异有统计学意义（t=-3.555，P<0.05），左腮腺D_mean、D₅₀和V₃₀分别平均降低了2.90%、2.73%和4.62%，差异有统计学意义（t=3.089、2.718、2.705，P<0.05）；右腮腺D_mean、D₅₀和V₃₀分别降低3.49%、3.44%和3.80%，与放疗前比较，差异均有统计学意义（t=2.781、2.958、4.275，P<0.05）；喉的D_mean平均降低3.29%（t=2.747，P<0.05）。结论局部晚期鼻咽癌患者在IMRT期间靶区和腮腺体积均会显著缩小；放疗中期有必要设计二程放疗计划，以此来提高靶区剂量并一定程度上降低靶区周围危及器官的剂量。

英文摘要:

Objective To investigate the anatomical changes and dose distribution deviations of locally advanced nasopharyngeal carcinoma (NPC) patients during intensity-modulated radiation therapy (IMRT). Methods Weekly cone beam CT (CBCT) was applied to investigate the anatomical changes of enrolled 18 patients with locally advanced NPC. Dosimetric deviations were investigated with new IMRT plans after 20 fractions. Results The volumes of gross tumor volume (GTV_nx) and GTV_nd were decreased by 3.15% and 5.67% weekly, and decreased by a total of 22.03% and 39.68%,respectiely. The volumes of left and right parotids were decreased by 4.93% and 5.26% weekly, and decreased by a total of 29.60% and 31.56%, respectively. The volumes of GTV_nd and parotids showed significant retraction in the first four weeks of radiation, then the retraction slowed down. The D₉₅ of PGTV_nd in Plan 2 decreased by 2.20% (t=2.382, P<0.05) compared that in the initial Plan 1, while there was no significant difference on the D₉₅ of PGTV_nx, PTV₁ and PTV₂.The D_mean, D₅₀ and V₃₀ of the left and right parotids in Plan 2 increased by 7.34%, 12.68%, 10.90% (t=-3.376, -3.738, -3.679,P<0.05), and 6.13%, 11.17%, 9.72% (t=-2.550, -2.446, -2.673, P<0.05), respectively, compared with Plan 1. The D_mean of larynx increased by 8.69% in Plan 2 compared with Plan 1 (t=-3.099, P<0.05). The D₉₅ of PGTV_nd in Plan(1+2) increased by 1.37% (t=-3.555, P<0.05) compared with Plan 2.The D_mean, D₅₀ and V₃₀ of the left and right parotids in Plan(1+2) were decreased by 2.90%, 2.73%, 4.62% (t=3.089, 2.718,2.705, P<0.05), and decreased by 3.49%, 3.44%, 3.80% (t=2.781, 2.958,4.275, P<0.05), respectively, compared with Plan 1. The D_mean of larynx decreased by 3.29% (t=2.747, P<0.05) in Plan(1+2) compared with Plan 1. Conclusions The volumes of GTV and parotids of locally advanced NPC patients showed significant shrinks during IMRT. Replanning is necessary during the middle of IMRT to improve the target coverage and to spare the organ at risks (OARs).

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