Short-Term Clinical Evaluation Of ¹²⁵I Particle Implantation For The Treatment Of Lung Malignant Solid Tumors Under Multimodal Imaging Guidance

Objective Through the radioactive particle therapy planning system,multimodal imaging was used to guide the preoperative tumor localization and biological target delineation of ¹²⁵I particle implantation,and postoperative dosimetry verification was carried out.Furthermore,the short-term clinical effect of¹²⁵I particle implantation in the treatment of lung malignant solid tumors was evaluated,in order to provide a basis for the determination of ¹²⁵I particle treatment regimen.Methods A prospective analysis was conducted on 54 patients with lung malignant solid tumors admitted to the Department of Nuclear Medicine,Northern Theater General Hospital,from January 2021 to June 2022.A total of 60 lesions were treated with¹²⁵I radioactive particle implantation.The patients were divided into a multimodal group（30 lesions,26 patients）and a control group（30 lesions,28patients）using a random grouping method.The multimodal group underwent tumor gross target volume（GTV）and biological target volume（BTV）delineation using multimodal imaging techniques,including enhanced chest CT and PET/CT.The control group underwent GTV delineation using enhanced chest CT alone.Preoperative imaging data were input into the treatment planning system（TPS）to develop the treatment plan,delineate the target volume,organs at risk,and 1cm and 2cm beyond the target volume,set the particle activity and prescription dose,generate the particle implantation path,quantity,and distribution,and finally create a dose-volume histogram.Dose-volume parameters such as V100 and D90 were recorded.Under the guidance of thin-slice CT,¹²⁵I particles were implanted into the planned positions using puncture needles.Immediate postoperative CT scans were performed to verify the spatial position of the particles and the post-implantation dosimetry parameters.Complications were also recorded.The quality evaluation of radioactive particle implantation followed the evaluation criteria of the British Columbia Cancer Agency.Based on the immediate postoperative verification of V100 and D90 in the target volume,the evaluation results were categorized into four groups: excellent,good,fair,and poor.A comparison was made between the two groups regarding the quality of implantation,average operation time,number of punctures,and number of particles implanted per unit volume.Chest CT scans were performed at 1,2,and 6 months postoperatively,and the treatment outcomes of the two groups were objectively evaluated.Results1.Quality of implantation of Multimodal group:Excellent（19 cases,63.33%）,Good（10 cases,33.33%）,Fair（1 case,3.33%）,Poor（0 cases,0/30）.Control group: Excellent（15 cases,50.00%）,Good（12cases,40.00%）,Fair（3 cases,10.00%）,Poor（0 cases,0/30）.There was no statistically significant difference between the two groups（P >0.05）.2.Average operation time of Multimodal group: 48.20 ± 15.04 minutes.Control group: 59.23 ± 16.58 minutes.The average operation time in the multimodal group was significantly shorter than that in the control group,with a statistically significant difference（t =-2.70,P = 0.009 < 0.05）.3.Number of punctures and particles implanted per unit volume of Multimodal group: 15.03 ± 6.30 punctures,67.63 ± 36.54 particles,0.88 ± 0.12 particles implanted per unit volume.Control group:19.50 ± 6.22 punctures,93.93 ± 42.14 particles,1.11 ± 0.07 particles implanted per unit volume.There were statistically significant differences between the two groups（P < 0.05）.When the lesion diameter was greater than 3cm,the number of particles implanted per unit volume in the multimodal group was significantly lower than that in the control group（P < 0.05）.However,when the lesion diameter was less than or equal to 3cm,there was no statistically significant difference between the two groups（P > 0.05）.4.Dosimetric parameters: There were no statistically significant differences in D90 before and after surgery in both groups（P > 0.05）.Multimodal group: D90 before surgery（range: 120.63-145.26 Gy,means: 132.37 ± 7.23 Gy）,D90 after surgery（range: 110.28-146.35 Gy,mean: 128.60 ± 13.58 Gy）.Control group: D90 before surgery（range: 107.25-130.85 Gy,mean: 119.35 ± 6.53 Gy）,D90 after surgery（range: 92.23-136.25 Gy,mean: 114.97 ± 13.96 Gy）.There was no statistically significant difference in D90 before and after surgery in either group（P > 0.05）.The V100 value in the multimodal group was significantly higher than that in the control group（P = 0.004< 0.05）.The difference is statistically significant.5.According to RECIST 1.1 criteria: Multimodal group: Local control rates at 1,2,and 6 months postoperatively were 96.66%,90.00%,and 93.33%,respectively.Objective response rates were46.66%,53.33%,and 63.33%,respectively.Control group: Local control rates at 1,2,and 6 months postoperatively were 93.33%,86.66%,and 73.33%,respectively.Objective response rates were43.33%,46.66%,and 36.66%,respectively.There were no statistically significant differences in local control rates and objective response rates at 1 and 2 months postoperatively between the two groups（P >0.05）.However,at 6 months postoperatively,the multimodal group showed significantly higher local control rates and objective response rates compared to the control group（P < 0.05）.6.Both groups had no severe complications.Multimodal group: Mild pneumothorax（6 cases）,needle tract bleeding（2 cases）,blood-tinged sputum（1 case）.The overall incidence of postoperative complications was 34.62%（9/26）.Control group: Mild pneumothorax（7 cases）,moderate pneumothorax（2cases）,minor intrapulmonary bleeding（2 cases）,air embolism（1case）.The overall incidence of postoperative complications was42.86%（12/28）.There was no statistically significant difference in the incidence of postoperative complications between the two groups（X²= 0.385,P = 0.535 > 0.05）.Conclusions1.The use of multimodal imaging guidance for ¹²⁵I particle implantation therapy in the treatment of malignant solid tumors in the lungs is safe and reliable.2.The treatment showed good local control rate,high efficacy rate,fewer needle insertions,and significantly reduced surgical time.3.Post-implantation dose verification demonstrated high agreement with the preoperative treatment plan,with excellent coverage of the prescribed dose（V100）.4.The number of particles implanted per unit volume was low,indicating good cost-effectiveness.5.When the tumor diameter（D）exceeded 3cm,the treatment not only improved patient outcomes but also reduced medical expenses.