呼吸状态对左侧乳腺癌根治手术后容积旋转调强放疗剂量的影响

Effect of Respiratory Status on Dose of Volumetric Modulated Radiotherapy Following Mastectomy for Patients with Left Breast Cancer

目的探讨左侧乳腺癌根治术后在DIBH与自由呼吸(FB)两种模式下的剂量学差异。方法随机选择20例左侧乳腺癌根治术后放疗(post-mastectomy radiation therapy,PMRT)患者,全部患者均行乳腺改良根治手术和腋窝淋巴结清扫术后,且腋窝淋巴结淋巴结转移≥4枚。所有入组患者均在DIBH和FB下进行了仰卧位的计划CT检查,靶区勾画和容积旋转调强放疗计划设计。最后用靶区覆盖率、靶区适形度指数(CI)、靶区均匀性指数(HI)和危及器官受量对两种方案进行定量评估。结果靶区体积在DIBH模式和FB模式下无统计学差异;而左肺体积具有明显统计学差异(P<0.05)。两种方案提供了接近的PTV覆盖率、HI、CI、右肺、左侧乳腺和肝脏受量。FB模式的左肺V5Gy和V20Gy分别为(51.36±3.25)%和(23.11±2.33)%,明显高于DIBH模式(P<0.05)。DIBH模式的心脏Dmean[(5.08±1.08)Gy]明显优于FB模式[(6.63±1.17)Gy]。结论对于接受PMRT的患者,与FB模式相比,DIBH模式对心脏和左肺的受照剂量可以显著降低,具有良好的临床潜力,值得在临床实践中广泛应用。

Objective To investigate the dosimetric differences between the 2 modes of DIBH and free breathing(FB)after radical left-sided breast cancer.Methods 20 patients with left-sided breast cancer who had undergone post-mastectomy radiation therapy(PMRT)were randomly selected.All of them had undergone modified radical mastectomy breast surgery and axillary lymph node dissection with≥4 axillary lymph node metastases.All enrolled patients underwent a planned supine CT scan,target delineation and volumetric rotation-modulated radiotherapy plan design under DIBH and FB.Finally,target coverage,target conformance index(CI),target uniformity index(HI)and organ at risk were used to quantitatively evaluate the two modes plans.Results There was no statistically significant difference in target volume between the DIBH and FB modes.However,there was a statistically significant difference in left lung volume(P<0.05).The two modes provided close dose to PTV coverage,HI,CI,right lung,left breast and liver.The left lung V5Gy and V20Gy were(51.36±3.25)%and(23.11±2.33)%,respectively,in the FB mode,which were significantly higher than those in the DIBH mode(P<0.05).The Dmean of the heart in the DIBH mode was significantly lower than that in the FB mode[(5.08±1.08)Gy]vs.[(6.63±1.17)Gy].Conclusion In PMRT,the dose to the heart and left lung can be significantly reduced by DIBH compared with FB,which has good clinical potential and is worthy deserves to be widely used in clinical practice.