Experiment Research And Dose Evaluation Of ¹²⁵I Radioactive Seeds Interstitial Brachytherapy In Lung Cancer Treatment

Objective:To verify the validity of ¹²⁵I radioactive seed implantation in the treatment of lung cancer xenografts in nude mice,and compare their own characteristics and advantages of¹²⁵I radioactive seeds implantation and external beam radiotherapy in the treatment of lung cancer xenograft in nude mice,to provide better treatment for the clinical treatment of lung cancer.Method:First of all we need to establish a nude mice model of lung cancer.This research need to cultivate Large-scale human lung adenocarcinoma cell A549.The human lung adenocarcinoma cell A549 which grow well will be subcutaneously injected into left lower limb partial dorsal area of the immunodeficient BABL/c nude mouse.The tumors size grew to 8¹0mm about seven weeks,and 18 nude mice that their tumor size meet the test requirement can be used for experiments after filtering.This 18 lung cancer nude mice were randomly divided into three groups,namely control group,external beam radioth-erapy group and ¹²⁵I seed implantation group.Each group includes 6 mice.Do MRI examination in the day before implementing the treatment and one week after implementing the treatment,and accurately measure the longest diameter of tumor and the shortest diameter which is perpendicular to the longest diameter,and calculate the tumor volume according to the formula.Then dissect these laboratory mice after one week when implementing,the tumor specimen and surrounding vital organs liver tumor need to do HE staining to observe the changes of tumor cell and liver tissue apoptosis and cell morphology;Through looking up the literature,we can know that the tumor volume equals the longest diameter times the shortest diameter by 2,then divided 2.Results:The tumor volume,s changes of ¹²⁵I seed implantation mice are obvious before implantation and after implantation,one week after implanting ¹²⁵I seeds the tumor volume was significantly reduced.Through statistical analysis,It shows that the changes of tumor volume is statistically significant（P<0.05）.The tumor volume of external beam radiother-apy mice also changes before and after treatment,and the difference is statistically sign-ificant（P<0.05）,but the changes of the volume are little and not significant when compared with ¹²⁵I seed implantation.For the control group of mice,the tumor volume continues to increase,but the change of tumor volume is not statistically significant（P>0.05）.Conclusion:¹²⁵I radioactive seed implantation and external beam radiotherapy both can effectively treat tumors.Comparing this two treatments,¹²⁵I radioactive seed implantation can kill cancer cells more significantly,and it is one of effective treatment for lung cancer,and When treating tumors with ¹²⁵I radioactive seeds,liver which is a vital organ around tumor have no obvious radiation damage.Objective: To evaluate the clinical value and dosimetric advantages of 125 I radioactive seed implantation and classic external beam radiotherapy through comparing each dosimetric parameters of 125 I radioactive seed implantation and classic external beam radiotherapy in the treatment of lung cancer,to provide a better choice for the clinical treatment of lung cancer.Methods: Collect 20 cases lung cancer patients of CT image-guided 125 I seed implantation in Shandong Province Institute of Imaging from March 2015 to May 2015.All these 20 patients include 15 cases male and 5 cases female.Use the TPS（treatment planning system）planning system of Zhuhai hokai Medical Equipment Co.,Ltd.to make preoperative planning.The prescription dose is 120 Gy.Then line out CTV（clinical target volume）in CT images and implant 125 I seeds in CTV,at the same time calculate the implanted 125 I particle number,spatial distribution and the dose distribution.The research select 125 I seeds that radioactive activity is 1.0m Ci per 125 I seed.The median implanted seeds number is 26（the seeds number range is from 5-84）.Explore the tumor target dose distribution,target conformity,the maximum dose the minimum dose and average dose of tumor target,the suffered dose of vital organs around target area,and also DVH chart.Then import the 20 cases original images data to 3D conformal radiotherapy treatment planning system of external beam radiotherapy（the treatment planning system is produced by Chengdu qilin technology co.,LTD.）.The prescription dose is 60 Gy.Explore the tumor target dose distribution,the maximum dose the minimum dose and average dose of tumor target,the suffered dose of vital organs around target area,and also DVH chart.And compare the dosimetric parameters of these two methods.Results: 1.For 125 I seeds implantation group,all cases indicate that D90 > MPD,it means that the suffered dose of 90% of the target area is more than the matching peripheral dose,which conforms to the internal radiation dose assessment standard.It means that the imp-lanted quality of all cases is very good,and the target dose conformity is also good.2.For the two methods of radiation therapy: internal radiation and external exposure,the percentage of target volume covered with 50% and 80% prescribed dose has no statistics difference（P>0.05）;While the percentage of target volume covered with 100% prescribed dose has statistics difference（P<0.05）.3.For the two methods of radiation therapy: internal radiation and external exposure,the irradiation dose of 80% and 90% target volume has statistics difference（P<0.05）;but the irradiation dose of 100% target volume has no statistics difference（P>0.05）.4.The average radiation dose of trachea and esophagus in 125 I particles implantation treatment is both less than the external irradiation treatment;and the difference between the two treatment method is also statistically significant（P<0.05）.When using these two methods to treat lung cancer,the suffered maximum radiation dose of spinal cord has no statistics difference（P>0.05）.5.For gross tumor volume（GTV）,compare 125 I seeds group and external exposure group,the maximum dose and average dose that the tumor target suffered have difference,and the difference is statistically significant（P<0.05）,and the dose of 125 I seeds group is higher than external beam radiotherapy group;while the difference of minimum dose between the two treatment methods is not statistically significant（P>0.05）.Conclusion: Compared with external radiation treatment,125 I radioactive seed implantation has so much advantages,such as the high conformity in target dose,high target radiation dose,and the low radiation dose of surrounding normal tissue.125 I radioactive seed implantation is a relatively safe and minimally invasive method of lung cancer treatment,it provides a more safe and effective treatment for clinical lung cancer treatment.