The Feasibility Study Of SPECT-CT For The Assessment Of ¹²⁵I Seeds Particle Dose Distribution And The Short-term Efficacy Of ¹²⁵I Seed Implantation In The Treatment Of Lung Malignant Tumors

Objective:Radioactive ¹²⁵I seed implantation is a new minimally invasive radiotherapy method for the treatment of malignant tumors.It has been widely used in clinical for intracranial tumors,head and neck tumors,pancreatic cancer,early prostate cancer,liver cancer,lung cancer,and refractoryThyroid cancer has remarkable curative effect.The efficacy of¹²⁵I seed implantation and the occurrence of adverse reactions are closely related to the dose distribution after radioactive seed implantation.The traditional postoperative verification method is to use the radioactive particle treatment planning system（TPS）for"simulation"calculation,but the TPS planning system has certain shortcomings and defects.This method must understand the activity of each particle and the internal tumorThe number of particles and accurate identification of particle positions can ensure the accuracy of dose calculation.This study aims to study the feasibility of single-photon emission computed tomography（SPECT）to evaluate the dose distribution of patients after¹²⁵I seed implantation.At the same time,we retrospectively studied the short-term efficacy of ¹²⁵I particles in the treatment of malignant lung tumors.Methods:Part 1:SPECT-CT scan of patients who have completed ¹²⁵I seed implantation in our hospital,complete the collection of the patient’s whole body scan image and the tomographic fusion scan image of the implantation site.According to the selection criteria,patients who meet the criteria were selected,and the TPS system was used for postoperative dose verification.By comparing the fusion image with the V100 value of TPS dose verification,it is evaluated whether the two evaluation methods are consistent with SPECT-CT scan and TPS dose verification.Part 2:Our hospital admitted 86 patients with advanced lung cancer from July 1,2017 to July 1,2018.Taking these 86 patients with exceptional stage lung cancer as the research object,the 86 patients were divided into two by random number method.The groups are the study group（n=43）and the reference group（n=43）.The reference group received sequential radiotherapy and chemotherapy,and the study group used CT-guided implantation of¹²⁵I particles to analyze the short-term efficacy of the two groups.Results:1.SPECT-CT can clearly display the shifted¹²⁵I particles;SPECT-CT tomographic fusion images,in the attenuation correction mode,the ratio of the volume of the 125I particles’nuclide concentration to the volume of the target area,TPS planning system verificationThe V100 obtained has a very good consistency between the two.2.Compared with the conventional radiotherapy and chemotherapy group,the short-term curative effect of¹²⁵I seed implantation in the treatment of lung malignant tumors is higher than the latter in effective rate and quality of life,and the incidence of adverse reactions is lower than the latter.conclusion:1.Use SPECT-CT to perform tomographic fusion scan on patients after ¹²⁵I seed implantation.The displayed image has a high consistency with the V100 dose line results verified by the TPS planning system.It can be used to evaluate the¹²⁵I seed implantation dose distribution;2.¹²⁵I particles have good short-term curative effect in the treatment of lung malignant tumors,the incidence of adverse reactions is low,and the postoperative quality of life is good.