RESUMO
Objective To study the effective dose and precaution time of the irradiation of the close contact from the radiators who underwent implantation of radioactive 125Ⅰ seeds so as to guide scientifically people how to avoid radiation damage.Methods Twenty patients with different types of cancer underwent implantation of radioactive 125Ⅰ seeds with the median value of implantation depth of 2.16 cm.Within 24hs after the operations the dose rates 30 cm and 100 cm from the skin were measured with pocket-size radiometer so as to imitate the situations of the close contacts.The effective doses and precaution times of different persons were calculated according to relevant formula.Results The dose rate a person received at the same time points (1,54,78,and 109 d,respectively) decreased along with the increase of the distance from the skin (t =5.962,5.961,5.961,5.962,P ＜ 0.05).and the dose rate a person received at the same distance from the skin decreased along with the extension of time (30 cm:t =6.236,6.236,6.235,P＜0.05;100 cm:t=7.310,7.315,7.314,P＜0.05).At different time points,the dose rates at 30 cm distance point were all significant higher than those at the 100 cm point (P ＜0.05).The adult living together,minors and pregnant women sharing the room,colleagues,adults who slept together with the patients began to reach the 50％ dose constraint values 0,54,78 and 109 days after the operation.Conclusions After their precaution time,it's safe to contact with the patients for the groups;otherwise,it's necessary to take some protect works within the precaution time.