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.

Objective To study investigate the dose accuracy that can be achieved with the method of bulk density assignment.Methods Sixteen cases of nasopharyngeal cancer patients and nineteen cases of esophageal cancer patients who accept radiotherapy in our department were selected.The planning CT images with bulk density assignment to different classes of tissues were applied to calculate the dose distributions,and then the resulting dose volume histograms (DVH) of the tumor and organs of risk were compared with the original treatment plan.The paired t-test was taken for dose comparison between two plans.Results The DVH comparison based on the planning CT and the bulk density assignment CT showed good agreements.With nasopharyngeal cancer patients,differences between the two plans about target and normal tissue were less than 1％.With esophageal cancer patients,the dose differences were less than 2％.Conclusion Preliminary results confirm that the bulk density assignment method can be applied to calculate the dose distributions.

Aim: Nowadays IMRT is widely used as a treatment for nasopharyngeal carcinoma, which requires more in accuracy of set-up and dose. This study is intended to find the proper external of the Target and to ensure dose homogeneity on the basis of protecting healthy tissues. Method: Offerring 12 set-up error cases through the image guide of IGRT, changing the location of ISO in TPS, and redesigning dose distribution without changing field distribution and weight. Analyzing the difference of dose change in Target and normal tissues between the original plan and the plan after moving ISO ratio of dose evaluation and original plan to make sure of the enlarge of the target and ensure well-distributed dose and the dose obtained by the normal tissues. When the set-up error is 5 mm, 8.3% GTV D99 and 16.7% CTVD95s dose decrease is more than 6%, When the set-up error is 2 mm, the dose decrease in GTVD99 and CTVD95 is less than 3%. The huger the error is, the more effective on dose distribution. Target CTV is more sensitive to set-up error, which means set-up error has more effects on target CTV than target GTV. Figuring out the enlarge of the GTV based on the formula 2.0Σ +0.7σ by Stroom. PGTV:x=4.33 mm; y=2.80 mm; z=4.18 mm. The plan produced based on this is an effective way to avoid the lack in dose caused by position error.

目的 探讨鼻咽癌1992年福州分期和2008年分期差异、CT和MRI对鼻咽癌病变的检出率和原发肿瘤靶区(GTV)勾画和体积计算的影响.方法 收集89例初治鼻咽癌患者的CT和MRI图像,分别按1992年福州分期和2008年分期标准进行,比较两种检查手段对各解剖部位的检出差异,挑选出CT与MRI检出有差异的39例,在TPS下进行GTV勾画及体积计算.结果 MRI在1992年福州分期中的参与使早期(T1+ T2)构成比降低,晚期(T3+ T4)构成比升高.鼻咽癌2008年分期使T3、T4期患者增多.两种分期标准对T2、T3分期差异有统计学意义(P=0.033,0.008)；在N1、N2的判断中,差异有统计学意义(P＜0.05).MRI较CT对头长肌、咽旁间隙、海绵窦、副鼻窦及颅神经的检出率明显提高；在对咽后淋巴结及颈部肿大淋巴结的形态、包膜、坏死、融合的显示方面明显优于CT.对39例CT和MRI成像有差异的病例进行靶区勾画,结果显示GTVMRI＞ GTVCT.结论 根据MRI图像进行1992年福州分期发现了更多的晚期病例,需要进行综合治疗(放疗+化疗)的患者增多,为治疗方案的选择提供了重要参考.以MRI为基础的2008年分期是指导鼻咽癌治疗的主要标准.按照MRI图像进行肿瘤靶区勾画能有效避免CT图像对肿瘤组织的漏诊以及对正常组织的误诊,既能加强局部控制,又能保护正常组织,对于鼻咽癌患者的治疗有利无弊.