Clinical Research Of Coplanar Template-assisted Technology In Interstitial ¹⁹²Ir Hypofractionated Brachytherapy For Locally Advanced And Advanced Non-small Cell Lung Cancer

Background and objective:Lung cancer is a major public health problem worldwidely.Non-small cell lung cancer?NSCLC?accounts for about 80%of all lung cancers.Interstitial brachytherapy with Computed tomography?CT?-guided has been proven to be an effective therapeutic modality for locally advanced and advanced NSCLC.Meanwhile,coplanar template assisted technology are also being used in particle implantation.The primary objective of this preliminary study was to examine the safety and feasibility of coplanar template-assisted technology in interstitial ¹⁹²Ir hypofractionated brachytherapy?HFBT?for patients with locally advanced and advanced NSCLC.The secondary objectives of this study was to compare the consistency of dosimetric parameters between the preoperative simulated plan and the actual delivered HFBT treatment plan using the coplanar template-assisted technique.Methods:Patients with pathologically confirmed locally advanced and advanced NSCLC who underwent template-assisted HFBT?28³2 Gy delivered in one fraction?were included in this study from October 2018 to August 2019.All patients performed CT-simulation after ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography(¹⁸F-FDG-PET/CT),and the CT images were transmitted to Oncentra V4.3 treatment planning system?TPS?to complete image fusion with the PET images to delineate the gross tumor volume?GTV?and organs at risk?OAR?.The specific implantation number and depth of the implant needles,as well as the dwell position and duration of the ¹⁹²Ir source,should be optimized according to GTV location in the simulated-preoperative plan?SPP?.According to the British Columbia Cancer Agency?British Columbia Cancer Agency,BCCA?criterion,evaluate the quality of the SPP and record dosimetric parameters(heterogeneity index[HI],conformity index[CI],and D₉₀,V₁₀₀,V₁₅₀ of GTV).In the actual HFBT procedure,disinfection,sterile drape spreading,and topical infiltration anesthesia were then performed.The needles were implanted according to the preoperatively planned needle path and depth.Screw caps were used to fix the implant needles in place.The CT image was then transmitted to the Oncentra V4.3 TPS for the actual-operative plan?AOP?,and requirements were the same as those for the simulated,and evaluated quality of the AOP according to BCCA criterion and recorded dosimetric parameters.After AOP was reviewed and approvaled,the patients were sent to the treatment room for HFBT.The intraoperative and postoperative complications of HFBT were observed to evaluate the safety and feasibility of HFBT.Dosimetric parameter(HI,CI,and D₉₀,V₁₀₀,V₁₅₀ of GTV)from both the SPP and the AOP were collected and compared.Results:A total of 21 patients with pathologically confirmed NSCLC were included in this study.All patients successfully performed template-assisted interstitial HFBT with CT guided.Patients did not experience any serious adverse events,and no postoperative death occurred.Intraoperative and postoperative complication including pain in 6 cases,intrapulmonary hematoma in 2 cases,pneumothorax in 7 cases and slight hemoptysis in 2 cases.In the simulated-plan group,evaluation indicated that the excellent group has 3?14.3%,3/21?cases,the good group has 11?52.4%,11/21?cases,the suboptimal group has 7?33.3%,7/21?cases,and no case in the poor group;in the delivered-plan group,there were 2?9.5%,2/21?cases in the excellent group,8?38.1%,8/21?cases in the good group,11?52.4%,11/21?cases in the suboptimal group,and none in the poor group.There were no significant differences between two groups??²=1.573,P=0.455?.In the simulated-plan group,the HI,CI,D₉₀,V₁₀₀00 and V₁₅₀ were?0.29±0.03?,?0.72±0.07?,?27.54±2.36?Gy,?85.82±4.25?%,?59.55±6.72?%vs.?0.30±0.05?,?0.70±0.09?,?26.57±1.96?Gy,?83.49±4.44?%,?58.29±7.11?%in the delivered-plan group,respectively.There were no significant differences in planned dosimetric parameters?All P>0.05?.Conclusion:The template-assisted interstitial HFBT is an effective method to treat the locally advanced and advanced NSCLC,which has the characteristics of minimally invasive and safety.The application of template-assisted technology can make implantation more accurate,which ensures a good consistency between simulated and operative plan for HFBT,and provide an effective tool for the standardization of interstitial brachytherapy,might have a good application prospect.