3种不同放疗技术在左侧乳腺癌保乳术后全乳腺放疗中的剂量学比较

目的 比较3种调强放疗技术在早期左侧乳腺癌保乳术后全乳腺放疗中的剂量学差异。 方法 回顾性分析2019年3月至8月在西安交通大学第一附属医院治疗的12例早期左侧乳腺癌保乳术后女性患者，年龄32~50（42.4±6.8）岁。分别设计基于固定角度适形调强放疗的混合调强（3DCRT+IMRT）、容积旋转调强放疗的混合调强（3DCRT+VMAT）和切线弧容积旋转调强放疗计划（t-VMAT），并比较3种放疗计划的计划靶区、危及器官剂量参数以及治疗效率的差异。组间数据比较采用配对t检验。 结果 3种调强放疗计划的靶区剂量分布和危及器官受量均能满足临床要求。3DCRT+IMRT和t-VMAT两种计划相比，3DCRT+VMAT的靶区剂量学指标适形性指数（0.84±0.05对0.74±0.06对0.79±0.06）和均匀性指数（0.10±0.03对0.14±0.03对0.13±0.03）最优，差异均有统计学意义（t=?9.01~6.47，均P<0.05）；3DCRT+IMRT对患侧（左）肺的V₅（35.92±8.01）%对（49.33±12.05）%对（60.58±12.94）%]、V₁₀（25.50±6.91）%对(26.92±7.23）%对（41.25±10.37）%]、D_mean（10.14±2.43）Gy对（11.07±2.88）Gy对（14.52±3.32）Gy]和健侧（右）肺的V₅（0.50±1.45）%对（2.17±3.76）%对（3.00±4.94）%]、D_mean（0.55±0.21）Gy对（1.79±0.58）Gy对1.75±0.70）Gy]及健侧（右）乳腺的V₅（0.17±0.58）%对（1.92±4.10）%对（8.25±8.61）%]、D_mean（0.86±0.38）%对（1.65±0.45）%对（2.46±0.86）%]的保护最好。3DCRT+VMAT的心脏V₃₀（4.50±2.88）%对（5.00±3.25）%对（8.42±2.78）%]、V₄₀（2.50±2.11）%对（3.25±2.53）%对（4.58±2.07）%]明显优于3DCRT+IMRT和t-VMAT，且差异均有统计学意义（t=?17.11~3.45，均P<0.05）。3DCRT+IMRT的平均机器跳数最小（280.90±52.18），t-VMAT的治疗时间最短。 结论 3DCRT+IMRT在低剂量区（<20 Gy）对健侧肺、患侧肺，健侧乳腺等危及器官的保护比较好，3DCRT+VMAT在提高靶区的均匀性和适形性方面有明显优势，且在高剂量区（>20 Gy）对患侧肺及心脏保护更好，t-VMAT缩短了治疗时间，提高了治疗效率和患者舒适度。

Dosimetric comparison of three different radiotherapy techniques in whole breast radiotherapy after breast-conserving surgery for left breast cancer

Objective To compare the dosimetry of three different intensity-modulated radiation therapy (IMRT) techniques in patients undergoing whole-breast radiotherapy after breast-conserving surgery for early left breast cancer. Methods Between March 2019 and August 2019, 12 female patients with early left breast cancer who underwent breast-conservative surgery in the First Affiliated Hospital of Xi'an Jiaotong University were analyzed retrospectively. The patient age was between 32 and 50 years, with an average of 42.4±6.8 years. The IMRT-based hybrid plan (3D conformal radiation therapy or 3DCRT + IMRT), the volumetric modulated arc therapy (VMAT)-based hybrid plan (3DCRT+VMAT), and the tangential VMAT plan (t-VMAT) were designed. The dosimetric parameters of the target and the organs at risk and treatment efficiency were compared among the three plans, and t-test was used for data analysis. Results Both the dose distribution in the target and dose to the organs at risk can meet the clinical requirements of the three plans. The conformal index (0.84±0.05 vs. 0.74±0.06 vs. 0.79±0.06) and uniformity index (0.10±0.03 vs. 0.14±0.03 vs. 0.13±0.03) of 3DCRT+VMAT were the best, and the difference was statistically significant compared with the two other plans (t=–9.01–6.47, all P<0.05). The protective effect of 3DCRT+IMRT was the best for V₅ ((35.92±8.01)% vs. (49.33±12.05)% vs. (60.58±12.94)%), V₁₀ ((25.50±6.91)% vs. (26.92±7.23)% vs. (41.25±10.37)%), D_mean ((10.14±2.43) Gy vs. (11.07±2.88) Gy vs. (14.52±3.32) Gy) of the ipsilateral (left) lung, V₅( (0.50±1.45)% vs.(2.17±3.76)% vs. (3.00±4.94)%), and D_mean ((0.55±0.21) Gy vs. (1.79±0.58) Gy vs. (1.75±0.70) Gy) of the contralateral (right) lung and the V₅ ((0.17±0.58)% vs. (1.92±4.10)% vs. (8.25±8.61)%) and D_mean ((0.86±0.38) Gy vs. (1.65±0.45) Gy vs. (2.46±0.86) Gy) of the contralateral (right) breast. 3DCRT+VMAT was significantly better than 3DCRT+IMRT and t-VAMT in V₃₀ ((4.50±2.88)% vs. (5.00±3.25)% vs. (8.42±2.78)%) and V₄₀ ((2.50±2.11)% vs. (3.25±2.53)% vs. (4.58±2.07)%) of the heart (t=–17.11–3.45, all P<0.05). The mean monitor unit of 3DCRT+IMRT was the lowest (280.90±52.18), but the treatment time of t-VMAT was the shortest. Conclusions The protective effect of 3DCRT+IMRT in the low-dose area (<20 Gy) for the ipsilateral lung, contralateral lung, and contralateral breast was better. 3DCRT+VMAT has obvious advantages in improving the uniformity and conformability of the target area and has better protection in the high-dose area (>20 Gy) for the contralateral lung and heart. Thus, t-VMAT shortens the treatment time and improves treatment efficiency and patient comfort.