Study On The Distribution Of Effective Radiation Dose And Character Of Toxic Side Effect When ¹²⁵Ⅰ Seeds Were Administrated To Treat The Patients With NSCLC

Objective:To analysis the distribution of effective radiation dose and character of toxic side effect when 125I seeds were administrated to treat the patients with NSCLC and to develope the better protocols that real-time location of effective radiation dose and dosimetric verification could be ensured according to RTOG/EORTC criteria of radiative respond in early or late stage.Methods:In 163 cases which were definitively diagnosesd with late stage NSCLC, the therapeutic proposals were established using radioactive seeds treatment planning system, in addition 125I seeds were implanted guiding with either CT scan or flexible fibrobronchoscope (FFB). It was confirmed that real-time location was correct in process and dosimetry was appropriate postoperatively. In order to meet to preoperative therapeutic proposal, an immediate replant procedure was applied if sparse or missing area were found. All cases were follow-up beginning 2 months after treament in which the local control rate representing in-time and overall survival rate representing of overall response served as assessing parameters. According to RTOG /EORTC criteria, the radiative respond rate in early and late stage were studied to investigate the toxicity of treatment.Results:1.In all cases, the total effective rates of 125I implantation were 97.4% in CT guiding group and 77.3%,90.6% in FFB guiding group respectively.lt were shown 92.2% and 45.5% of 1 yr and 2 yrs survival rate in CT guiding group, as well as 80.3% and 43.8% in FFB guiding group.2.The average exposure doses of neoplasm, attested by dosimetric verification, were 153.7 Gy and 154.5 Gy which are close to double of prescription dose (PD) and in appropriate range of r.The exposure doses of the heart/lung and spinal cord by CT scan guided were 31.0 Gy and 7.5 Gy respectively, and they were obvious lower than the tolerated dose of normal organization tissue/organ. In the end of follow-up duration (after 2yrs of treatment), thoracic CT scan directed CR and PR of CT guiding group were 26.2%and 71.3% and FFB guiding group were 22.7% and 54.5%. It also demonstrated irradiate toxic reaction rate 26.2%and 71.3% in early stage and late stage of CT guiding group, but no evidence of irradiate toxic reaction were discovered in FFB guiding group.Conclusion:When the radioactive 125I seeds were implanted into the bady, the strict implanting location and dosimetry verification limited by radioactive seeds treatment planning system are uniform to guarantee the effect of treatment. In other hand, the correct target location provide decreasing of radioation dose accepted by perilesional normal tissue and avoiding side injure of peri-targeting normal tissue,It is demonstration that 80Gy of effective prescription dose could give a high radiation dose to tumor lesions and get a significant control effect so that the episodes of toxic reaction reduced remarkably.