乳腺癌仿真模体术后胸壁放疗方法的比较研究

Study on radiotherapy method with simulation phantom for breast cancer after radical mastectomy

目的 使用MOSTET探测器观察分析乳腺癌术后5种常用放疗技术在模体中的剂量分布特点,同时验证TPS计划剂量准确性,为临床治疗方案及技术选择提供剂量学依据.方法 使用高仿真模体模拟成年女子左侧乳腺癌术后患者.对患侧胸壁靶区的代表测量点及其不同深度测量点进行标记定位后,在TPS上分别设计正向IMRT、逆向IMRT、3DCRT、6 MeV电子线、9 MeV电子线照射方案.最后对模体进行模拟照射,并对各点进行实时测量.采用方差分析检验5种方法间总差异.结果 正向IMRT、逆向IMRT、3DCRT、6 MeV电子线、9 MeV电子线实测平均剂量在表面的分别为74.32、69.21、73.97、75.86、81.41 cGy （F=3.36,P＜0.05）,0.5cm深度的分别为95.59、93.37、96.78、99.63、94.97 cGy（F=2.40,P＞0.05）,1.0cm深度的分别为103.42、102.53、103.48、88.89、101.36 cGy （F=7.19,P＜0.05）,近胸壁肺的分别为82.74、68.24、85.34、21.49、75.02 cGy （F=46.43,P＜0.05）.5种方法的平均剂量偏差在表面的为-8.04％（-6.57％ --11.93％）,0.5 cm深度的为-1.95％（2.15％--5.90％）,1.0 cm深度的为0.65％（-2.87％ - 3.22％）,近胸壁肺的为-3.53％（3.90％--8.93％）.结论 MOSFET探测器配以相应的仿真模体可以测量体内某部位的实际剂量,对放疗QA与QC提供了一种较好方法,亦可用于评价不同放疗技术的剂量学特点.MOSFET探测器适用于乳腺癌放疗的在体剂量监测,指导补偿膜的间隔使用以调整剂量,纠正误差,提高靶区吸收剂量的准确性.

Objective To study the dose distribution of five clinical technologies commonly used in simulation phantom of breast cancer after radical mastectomy are observed and analyzed by using MOSFET detector.The dose validation from TPS plan is tested for clinical treatment.Methods High simulation inhomogeneous equivalent phantom of human body is used to simulate the typical patient after the operation of left breast cancer.The kay points and other points on behalf of depth to the region of interest with side of the chest wall are marked.Five radiotherapy plans （FIF-IMRT、IMRT、3DCRT、6 MeV-electron beam,9 MeV-electron beam） were designed separately on TPS based on phantom image series.After confirmed,the plans are delivered to the phantom and the dosimetrical quantities are measured.Using analysis of variance test the difference in the five methods.Results FIF-IMRT,IMRT,3DCRT,6 MeV-electron beam,9 MeV-electron beam,Five method actual measured doses respectively：Surface 74.32 cGy,69.21 cGy,73.97 cGy,75.86 cGy,81.4 1 cGy （F =3.36,P 〈 0.05）;0.5 cm Depth 95.59 cGy,93.37 cGy,96.78 cGy,99.63 cGy,94.97 cGy （F =2.40,P 〉 0.05）;1.0 cm Depth 103.42 cGy,102.53 cGy,103.48 cGy,88.89 cGy,101.36 cGy （F =7.19,P 〈 0.05）;Nearly chest wall of lung 82.74 cGy,68.24 c Gy,85.34 cGy,21.49 cGy,75.02 cGy （F =46.43,P 〈 0.05）.Compared to the dose value in TPS,dose delivered to Surface is lower at 8.04% （-6.57% to-11.93%）,points at 0.5 cm is lower at 1.95% （2.15% to-5.90%）,points at 1 cm is higher at0.65% （-2.87% to3.22%）,lungislowerat3.53% （3.90% to-8.93%）.Conclusions MOSFET detector with the corresponding simulation phantom can be used to measure the actual dose in a portion of body,and to evaluate the dosimetrical characteristics of different radiotherapy techniques.MOSFET detector is suitable for real-time,in vivo measurement of radiation dose during radiotherapy in breast cancer patients,so that the physicians are able to change treatment plan in time to ensure the accuracy of target dose.