非共面野在鼻腔非霍奇金淋巴瘤调强放疗中的应用

A treatment plan using non-coplanar intensity modulated radiation for nasal non-Hodgkin lymphoma

目的通过对共面与非共面调强放疗计划的比较,探讨二者在鼻腔非霍奇金淋巴瘤调强放疗中的剂量学差异。方法选取10例鼻腔非霍奇金淋巴瘤患者,分别设计1组共面7F调强计划(7野均分),2组非共面7野调强计划7F-N1(4个共面射野和3个矢状面射野)和7F-N2(5个共面射野和2个矢状面射野)。比较3组计划的靶区剂量学指标D_(2%)、D_(98%)、D_(mean)、D_(50%)、V_(100%)、V_(107%)、均匀性指数(HI)、适形度指数(CI),机器跳数(MU)和危及器官的剂量学指标。结果 7F-N1与7F相比,D_(98%)的均值减小了0.06(P<0.05);7F-N2与7F相比,V_(100%)的均值减小了0.30(P<0.05)。7F-N2与7F-N1相比,靶区各剂量学指标及机器跳数无统计学差异。7F-N1与7F相比,患侧晶体、健侧晶体、健侧眼球和健侧视神经的Dmax的均值分别减少2.15、2.63、6.88、3.53 Gy(P<0.05),脑干D_(max)的均值增加6.75 Gy(P<0.05),患侧腮腺、健侧腮腺的D_(mean)的均值分别降低了3.77、4.65 Gy(P<0.05)。7F-N2与7F相比,健侧晶体、患侧眼球、健侧眼球、患侧视神经、健侧视神经和视交叉的D_(max)的均值分别下降了1.27、1.95、5.10、3.36、4.35,4.78 Gy(P<0.05),患侧腮腺、健侧腮腺的D_(mean)的均值分别下降了3.20、2.48 Gy(P<0.05)。7F-N2与7F-N1相比,患侧晶体和健侧晶体的D_(max)的均值分别增大了1.41、1.36 Gy(P<0.05),患侧视神经和视交叉的D_(max)的均值分别减少了2.76、4.66 Gy(P<0.05),健侧腮腺的D_(mean)的均值增加了2.17 Gy(P<0.05)。结论在鼻腔非霍奇金淋巴瘤的放疗中,7F-N1较7F及7F-N2在保护晶体及腮腺方面更具优势。

Objective The dosimetric differences between coplanar and non-coplanar intensity modulated radiotherapy（IMRT） plannings in nasal non-Hodgkin lymphoma（NHL） radiotherapy were discussed.Methods 7 F plans（seven equally spaced coplanar fields）,7 F-N1 plans（4 coplanar fields and 3 non-coplanar fields in the sagittal plane） and 7 F-N_2 plans（5 coplanar fields and 2 non-coplanar fields in the sagittal plane）have been designed for ten patients with NHL. The D_（98%）, D_（2%）, D_（mean）, D_（50%）, V_（100%） and V_（107%） heterogeneity index（HI）and conformity index（CI）of PTV coverage parameters for them have been analyzed. Also, the machine monitor unit（MU） and the absorbed dose of OARs have been compared. Results Compared with 7 F, the mean value of D_（98%） in 7 F-N_1 decreased by 0.06 Gy（P〈0.05） and the mean value of V_（100%） in 7 F-N_2 decreased by 0.3（P〈0.05）. Comparing 7 F-N_1 with 7 F, the mean value of Dmaxfor ipsilateral and contralateralcrystalline lens, as well as contralateral eyeball and contralateral optic nerve, decreased by 2.15 Gy,2.63 Gy,6.88 Gy and 3.53 Gy（P〈0.05）, respectively; the mean value of Dmaxfor Brainstem increased by 6.75 Gy（P〈0.05）, the mean value of Dmeanfor ipsilateral and contralateral parotid gland decreased by 3.77 Gy and4.65 Gy（P〈0.05）, respectively. In comparison with 7 F, the mean values of Dmaxof contralateral crystalline lens, ipsilateral and contralateral eye ball, ipsilateral and contralateral optic nerve as well as optic chiasm in 7 F-N_2 decreased by 1.27 Gy, 1.95 Gy, 5.10 Gy, 3.36 Gy, 4.35 Gy and 4.78 Gy（P〈0.05）, respectively;the mean value of Dmeanfor ipsilateral and contralateral parotid gland decreased by 3.20 Gy and 2.48 Gy（P〈0.05）, respectively. Compared with 7 F-N1, the average value of D（max） of ipsilateral and contralateral crystalline lens for 7 F-N_2 increased by 1.41 Gy and 1.36 Gy（P〈0.05）, while the mean value of D（max） of ipsilateral optic nerves and optic chiasm in 7 F-N_2 decreased by 2.76 Gy and 4.66 Gy（P〈0.05）, respectively;the mean value of D_（mean） for contralateral parotid gland increased by 2.17 Gy（P〈0.05）. Conclusion In the radiotherapy for non Hodgkin lymphoma of the nasal cavity, 7 F-N_1 is more advantageous than 7 F and 7 F-N_2 in the protection of crystalline lens and parotid glands.