胸中段食管癌三维适形放疗、调强放疗及旋转调强放疗的剂量学研究

 目的　研究胸中段食管癌三维适形放疗（3DCRT）、调强放疗（IMRT）、旋转调强放疗（IMAT）3种放疗计划的剂量差异。方法　选取胸中段食管癌患者15例，以Varian Eclipse 8.6计划系统分别设计3DCRT、IMRT、IMAT 3种放疗计划，其中3DCRT采用5～8个共面射野，IMRT采用7个共面射野，IMAT采用2个弧度。比较3种计划的剂量学差异。结果　IMRT、IMRT的靶区均匀指数（HI）、适形指数（CI）、95 % 计划靶体积（PTV）体积剂量均优于3DCRT，全肺V5、V20、V35、心脏V30受照剂量低于3DCRT（t＝2.531，P＜0.05），而在全肺V10、V15、V25、V30、全肺平均、心脏平均、脊髓Dmax剂量之间三者的差异均无统计学意义（t＝1.325，P＞0.05）。结论　IMAT与IMRT在胸中段食管癌放疗靶区体积剂量覆盖和危及器官保护方面相似，二者均优于3DCRT。IMAT的机器跳数和照射时间均少于IMRT。

Dosimetry study on conformal radiation therapy, intensity modulated radiation therapy and intensity modulated arc radiotherapy in middle thoracic esophageal cancer

Objective　To compare the dosimetry of three different radiation therapy plans [three-dimensional conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT), intensity modulated arc radiotherapy (IMAT)]. Methods　Selected 15 cases with middle thoracic esophageal cancer, Varian Eclipse 8.6 planning systems were designed with 3DCRT, IMRT, IMAT, 3DCRT using 5－8 coplanar radiation fields, IMRT using 7 coplanar radiation fields, IMAT using 2 radians. Three planned dose difference were compared. Results　Compared with 3DCRT, IMRT and IMAT were better with heterogeneity index (HI),conformality index (CI), VPTV 95 %, V5, V20, V35 of total lung, and V30 of heart (t = 2.531, P < 0.05). There was no statistically significant difference for the V10, V15, V25, V30, mean dose of total lung, the mean dose of heart, the maximum dose of spinal cord, and the minimum dose of PTV among the three plans (t = 1.325, P > 0.05). Conclusion　IMAT and IMRT are similar in the middle thoracic esophageal cancer radiotherapy target volume dose coverage and organs at risk protection, they are better than 3DCRT. IMAT in the monitor units and delivery time are less than IMRT.