中文摘要：

目的 ：比较宫颈癌三维后装放射治疗计划中剂量归一基于参考点和参考体积的剂量学参数。方法 ：为27例宫颈癌患者分别制定处方剂量基于A点的常规计划与基于靶区体积的逆向计划[以90%高危临床靶体积（high-risk clinical target volume,HR-CTV）的剂量（D90）〉处方剂量（6 Gy）为目标制定计划]。比较这2种计划中危及器官（膀胱、直肠、乙状结肠）的D1cc和D2cc（1cm~3和2 cm~3受到的最低照射剂量）、处方剂量覆盖体积、适形指数（conformal index,CI）和治疗时间。结果 ：逆向计划中的危及器官膀胱、直肠和乙状结肠的D1cc和D2cc均较常规计划中的低（P值均〈0.05）。以膀胱、直肠和乙状结肠的2 Gy分次放疗等效剂量（equivalent dose in 2 Gy per fraction,EQD2）分别≤90 Gy、≤75 Gy和≤75 Gy为标准,逆向计划中符合膀胱、直肠和乙状结肠受照剂量限量标准的患者比例均高于常规计划（P值均〈0.05）。逆向计划的处方剂量覆盖体积小于常规计划[分别为（81.25±34.7）和（161.32±82.62）cm~3,P=0.000]。逆向计划的CI值显著高于常规计划（分别为0.49±0.15和0.30±0.14,P=0.000）。逆向计划的治疗时间较常规计划显著缩短[分别为（325.70±83.27）s和（507.40±170.79）s,P=0.000]。结论 ：在宫颈癌三维后装放射治疗中,处方剂量基于靶区体积的逆向计划的靶区剂量适形度、危及器官保护和治疗时间均优于常规计划。

英文摘要：

Objective：To compare the dosimetry parameters for dose normalized based on reference point and reference volume in three-dimensional intracavitary brachytherapy of cervical cancer.Methods：Reverse plan[based on D90（dose covering 90%of high-risk clinical target volume） 〉6 Gy of prescribed dose]and general plan（based on point A to reach prescribed dose） were designed for 27 cervical cancer patients treated with intracavitary brachytherapy.Dosimetry parameters including D1cc（dose to 1 cm~3） and D2cc（dose to 2 cm~3） of organs at risk（OARs）（bladder,rectum and sigmoid colon）,target dose coverage,conformal index（Cl）,and treatment duration between these two plans were compared.Results：D1cc and D2 cc of OARs including bladder,rectum and sigmoid colon in reverse plan were lower than those in general plan（all P 〈 0.05）.The proportions of patients with equivalent dose in 2 Gy per fraction（EQD2） 〈 90 Gy,〈 75 Gy and 〈 75 Gy of bladder,rectum and sigmoid colon,respectively,were higher in reverse plan than those in general plan（all P 〈0.05）.The volume covered by prescribed dose in reverse plan was smaller than that in the general plan（81.25±34.7 cm~3 vs 161.32±82.62 cm~3,P = 0.000）.The Cl value of reverse plan was higher than that of the general plan（0.49±0.15 vs 0.30±0.14,P = 0.000）.The treatment duration of reverse plan was shortened as compared with that of the general plan（325.70±83.27 s vs 507.40±170.79 s,P = 0.000）.Conclusion：The Cl value,OARs protection,and treatment duration of reverse plan are superior to general plan for intracavitary brachytherapy of cervical cancer.