Study On The Relative Effective Prescription Dose Of ¹²⁵I Seed Implantation In The Treatment Of Retroperitoneal Lymph Node Metastases

Background Prescription dose is not only one of the most important factors affecting the efficacy of ¹²⁵I seed,but also closely related to the incidence of postoperative complications.Objective Based on the postoperative verification parameter D90 of the treatment planning system（TPS）,to explore the relative effective prescription dose of ¹²⁵I seed implantation in the treatment of retroperitoneal lymph node metastases.Methods Forty-eight patients with retroperitoneal lymph node metastasis diagnosed by pathology in our hospital from July 2018 to December 2020 were treated with interstitial implantation of ¹²⁵I seeds under the guidance of CT/B ultrasound,and the results were analyzed retrospectively.The CT images of patients scanned after operation were introduced into TPS,to delineate the target area and crisis organs and to verify whether the postoperative Matched peripheral dose（MPD）was within the allowable range of error（±15%）from the prescription dose planned before operation.All patients were divided into three groups according to D90 after operation,17patients received group A（80-100Gy）,16patients received group A（100-120Gy）,15patients received group A（120-140Gy）.The differences of tumor local control rate,objective remission rate,visual analog scale score and complication rate of the three groups at 1,3 and 6 months were observed and compared.Results 1.After 1 month,the LCR and ORR of the group A,Group B,Group C were41.2%and 23.5%,75.0%and 37.5%,93.3%and 73.3%,respectively.The difference between the three groups has statistically significant（P<0.05）,and the LCR and ORR of the group C are higher than those in group A and group B.After 3 month,the LCR and ORR of the group A,Group B,Group C were 52.9%and 29.4%,81.3%and 62.5%,93.3%and 80.0%,respectively.The difference between the three groups has statistically significant（P<0.05）,and the LCR and ORR of the group C are higher than those in group A and group B.After 6month,the LCR and ORR of the group A,Group B,Group C were 52.9%and 41.2%,81.3%and 68.8%,93.3%and 86.7%,respectively.The difference between the three groups has statistically significant（P<0.05）,and the LCR and ORR of the group C are higher than those in group A and group B.2.After 1 month,VAS scores in group A,group B,and group C were4.59±2.83,3.88±2.19,2.07±1.53,and the three sets of data were more statistically significant（P<0.05）.There was no statistical significance between group A and group B（P>0.05）,but there was statistical significance between group A and group C,group B and group C（P<0.05）,The VAS score of group C was lower than that of group An and group B.After 3 month,VAS scores in group A,group B,and group C were 4.53±2.52,3.06±1.77,1.60±1.40,and the three sets of data were more statistically significant（P<0.05）.The overall comparison of the three groups of data and the pairwise comparison between the three groups were statistically significant（P<0.05）.The VAS score of group C was lower than that of group A and group B.After 6 month,VAS scores in group A,group B,and group C were 4.52±2.42,3.00±2.07,1.40±1.64,and the three sets of data were more statistically significant（P<0.05）.The overall comparison of the three groups of data and the pairwise comparison between the three groups were statistically significant（P<0.05）.The VAS score of group C was lower than that of group A and group B.3.The incidence of postoperative fever in group A,B and C was 29.4%（5/17）,37.5%（6/16）,33.3%（5/15）,the difference was not statistically significant（P>0.05）,the symptoms disappeared after symptomatic treatment.The incidence of postoperative puncture site pain in group A,B and C was 64.7%（11/17）,56.3%（9/16）,66.7%（10/15）,and the difference was not statistically significant（P>0.05）,no related treatment was performed,and the pain relieved spontaneously after 2 days.During the follow-up period of 6 months,there were no complications such as bleeding,infection,particle displacement,myelosuppression and radiation damage of surrounding tissues and organs.Conclusion 1.¹²⁵I seed implantation is effective in the treatment of retroperitoneal lymph node metastases,which can effectively control pain and improve the quality of life of patients with less trauma,less complications and high safety.2.In the treatment of retroperitoneal lymph node metastasis with ¹²⁵I seed implantation,the clinical effect of 120-140Gy dose is the best,and with the increase of prescription dose,LCR and ORR show an upward trend,while VAS score shows a downward trend,which is worth further popularizing and applying in clinic.