Application Of Whole-body Dynamic Radiation Monitoring System In Early Diagnosis Of Differentiated Thyroid Cancer After ¹³¹I Treatment

ObjectiveDue to the radiation safety issues,the residual body radioactivity（RBA）or external body dose rate（EDR）must be monitored after differentiated thyroid cancer（DTC）patients taking radioiodine.A new machine,the whole-body dynamic radiation monitoring system（DWBRS）,can evaluate the activity of residual ¹³¹I in patients,and provide the distribution and radiation in the body,especially the iodine metabolism in the neck.We aim to evaluate the correlation between residual radioactivity in the neck of patients with differentiated thyroid cancer treated with ¹³¹I,RBA measured by DWBRS and EDR measured by traditional instruments（LUDLUM MODEL 375AREA MONITOR monitoring system）,and analyze the correlation between RBA decay rate and clinical and laboratory factors,so as to predict the time point of safe,scientific and reasonable discharge plan.MethodsThe cross-sectional study identified 83 patients with DTC who received ¹³¹I treatment from February to March 2021.They measured RBA with whole-body dynamic radiation monitoring system and EDR with LUDLUM MODEL 375 AREA MONITOR monitoring system to estimate the residual radioactivity of patients 2 hours,20 hours and 43 hours after receiving ¹³¹I treatment.Pearson correlation coefficient is used to analyze the relationship of three groups at three different time points.Single factor analysis and multiple regression analysis were used to evaluate the correlation between the patient’s basic information and relevant examination results and the metabolic rate of systemic radioactivity.ResultsThe data difference of neck residual radioactivity,RBA and EDR at each time point was statistically significant（P<0.05）.The neck EDR and residual radioactivity gradually weakened with the increase of time after iodine intake（RBA and neck,43h r=0.51;EDR and neck,43h r=0.64）.The measured values between RBA and EDR are correlated（r≥0.87）,but the absolute consistency is not perfect.In the analysis of clinical and laboratory factors affecting ¹³¹I metabolic rate,TSH,FT3,FT4,Tg,creatinine,N stage,and gender are the relevant factors affecting the discharge time of DTC patients after taking ¹³¹I,among which TSH,FT3,FT4,Tg,creatinine values are positively correlated with the discharge time;N stage,gender and discharge time were negatively correlated.