Radiation Dose Monitor And Protection After Implantation Of Radioactive ¹²⁵I Seeds

Objective:To study the relationship between radiation dose and the implatation depth,the number of¹²⁵I seeds,postoperative time,physical distance and protective measures after radioactive ¹²⁵I seeds implantation,in order to guide the clinical protection scientifically.Methods:From November 2016 to August 2017,48 patients with malignant tumors were selected in the minimally invasive interventional ward of Zhongshan Hospital Affiliated to Dalian University.These patients received radioactive ¹²⁵I seeds implantation surgery under the guidance of CT.Then we tested the radiation dose rates respectively in different time and distances by using a gamma ray detector.The testing was conducted on the day after surgery,2 months,4 months and 6 months later.The measuring positions were 0 m?the body surface?,0.3 m,0.5 m,1 m,2 m,3m and 4m away from the body surface.We conducted experiments under 3 different conditions when patients wore nothing,wore 0.25 mmPb lead clothing and wore 0.50mmPb lead clothing.The results were compared to the environmental radiation dose rates.Results:Under similar conditions,the radiation doses of of the superficial tumor group were significantly higher than that of the deep tumor group.Under the circumstances without protective lead clothing:the safe distances of patients with superficial tumors who received less than 60 seeds were 3 m on the day after surgery,2 m at 2 months after surgery,0.3 m at 4 months after surgery,and these patients achieved a safe state on body surface 6 months after surgery.The safe distances of patients with superficial tumors who received more than 60 seeds were 4m on the day after surgery,3 m at 2 months after surgery,1 m at 4 months after surgery,and these patients achieved a safe state on body surface 6 months after surgery.The safe distances of patients with deep tumors who received less than 60seeds were 2 m on the day after surgery,1 m at 2 months after surgery,and these patients achieved a safe state on body surface 4 months after surgery.The safe distances of patients with deep tumors who received more than 60 seeds were 2 m on the day after surgery and 2 months after surgery,and these patients achieved a safe state on body surface 4 months after surgery.Under the protection of 0.25 mmPb lead clothing:the safe distances of patients with superficial tumors who received less than 60 seeds were 0.3 m on the day after surgery,and these patients achieved a safe state on body surface 2 months after surgery.The safe distances of patients with superficial tumors who received more than60 seeds were 0.5 m on the day after surgery,0.3 m at 2 months after surgery,and these patients achieved a safe state on body surface 4 months after surgery.Patients with deep tumors who received less than 60 seeds achieved a safe state on body surface on the day after surgery.The safe distances of patients with deep tumors who received more than 60 seeds were 0.3 m on the day after surgery,and these patients achieved a safe state on body surface 2 months after surgery.Under the protection of 0.50 mmPb lead clothing:patients with superficial tumors who received less than 60 seeds achieved a safe state on the body surface on the day after surgery;Patients with superficial tumors who received more than 60seeds reached a safe state 0.3 m away from the body surface on the day after surgery,and the body surface achieved a safe state 2 months after surgery.All the patients with deep tumors achieved a safe state on the body surface on the day after surgery.Conclusion:Implatation depth has a significant effect on radiation dose.Under similar conditions,the radiation doses of the superficial tumor group are significantly higher than the deep tumor group.All patients could reach a safe state at body surface6 months after ¹²⁵I seed implantation surgery,and they can be in contact with others for long-term without protective measures.Lead clothing plays an important role in radiation protection.Generally,0.25 mmPb lead clothes can effectively shield most of the radiation in practice.When the seeds are implanted in shallow locations or when a large number of seeds are implanted,0.50 mm Pb lead clothes should be used for protection.Clinical individualized radiation protection guidance should be given according to the specific circumstances,such as the number of seeds,the planting depth,and the postoperative time,and so on.