左乳癌根治术后两种调强放疗计划的甲状腺辐射剂量研究

袁美芳; 杨毅; 孙梦真; 文晓博; 赵彪

doi:10.7619/jcmp.20213277

左乳癌根治术后两种调强放疗计划的甲状腺辐射剂量研究

Study on thyroid radiation dose of two intensity-modulated radiotherapy plans after radical mastectomy of left breast cancer

摘要

摘要:
目的分析左乳癌术后静态调强放疗（sIMRT）计划和容积旋转调强放疗（VMAT）计划的甲状腺受照剂量特点。
方法回顾性选取68例左乳癌根治术后放疗患者作为研究对象，应用Pinnacle³ 10.0计划系统分别设计sIMRT计划和VMAT计划，在肿瘤靶区均归一到相同剂量指标的前提下，比较sIMRT计划和VMAT计划危及器官的受照剂量。
结果 VMAT的左肺接受5 Gy辐射剂量体积（V₅）和接受20 Gy辐射剂量体积（V₂₀）、心脏接受30 Gy辐射剂量体积（V₃₀）和平均辐射剂量（D_mean）均低于sIMRT，差异有统计学意义（P＜0.05）；sIMRT和VMAT的左侧甲状腺V₅、接受10 Gy辐射剂量体积（V₁₀）、V₂₀基本达100.00%，差异无统计学意义（P＞0.05），但VMAT的左侧甲状腺V₃₀、接受40 Gy辐射剂量体积（V₄₀）、接受50 Gy辐射剂量体积（V₅₀）和D_mean低于sIMRT，差异有统计学意义（P＜0.05）；VMAT的右侧甲状腺V₂₀和D_mean低于sIMRT，差异有统计学意义（P＜0.05）。
结论 sIMRT、VMAT技术均能满足临床要求，其中VMAT对甲状腺的保护作用显著优于sIMRT，且左侧甲状腺受照剂量较高、右侧甲状腺受照剂量较低，如何最大限度降低甲状腺受照剂量还需进一步研究。

Abstract:
Objective To analyze thyroid radiation dose of postoperative static intensity modulated radiation therapy (sIMRT) and volumetric intensity-modulated arc therapy(VMAT) for left breast cancer after left breast cancer surgery.
Methods A total of 68 patients with radiotherapy after radical mastectomy of left breast cancer were retrospectively selected. The sIMRT and VMAT plans were designed using Pinnacle³ 10.0 planning system, the dosages of organs at risk were compared between the two groups under the premise that the tumor target was normalized to the same dose.
Results The percentage of volumes of the left lung exposed to radiation dose of 5 Gy(V₅), 20 Gy(V₂₀), percentage of volume of the heart exposed to radiation dose of 30 Gy(V₃₀) of the heart, and mean radiation dose (D_mean) by VMAT were lower than those of the sIMRT(P < 0.05). V₅ of left thyroid, exposed to radiation dose of 10 Gy(V₁₀) and V₂₀ of both plans basically reached 100.00%, but there were no statistical differences (P > 0.05), while V₃₀, percentage of volume of left thyroid exposed to radiation dose of 40 Gy (V₄₀), exposed to radiation dose of 50 Gy(V₅₀) and D_mean of VMAT were significantly lower than sIMRT (P < 0.05); V₂₀ of the right thyroid and D_mean of VMAT were significantly lower than those of sIMRT (P < 0.05).
Conclusion Both of the two radiotherapy techniques can meet the clinical requirements. VMAT is superior to IMRT in thyroid protection and the radiation dose of the left thyroid is larger than that of the right thyroid. Further study is needed on how to minimize the thyroid exposure dose.

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