ABSTRACT
Objective@#To evaluate the residual radioactivity after 131I treatment in postoperative inpatients with differentiated thyroid carcinoma (DTC) using service robot in nuclear medicine ward, and assess the time for patients to be released from isolation.@*Methods@#From September 2017 to June 2018, 297 patients (94 males, 203 females, age: 19-80 years) with DTC who underwent 131I treatment after surgery were included. According to the purpose of treatment and the prescription dosage of 131I, patients were divided into 8 groups: 4 groups accepted 131I remnant ablation therapy (RAT) with different dosages, which were 3 700 MBq (RAT1, n=34), 4 440 MBq (RAT2, n=122), 5 550 MBq (RAT3, n=81) and 7 400 MBq (RAT4, n=27), respectively; 4 groups had 131I treatment for recurrent/metastatic lesions (RMLT), and the dosages were 3 700 MBq (n=1), 4 440 MBq (n=2), 5 550 MBq (n=14) and 7 400 MBq (n=16). At 4, 24, 48 and 72 h after 131I administration, the dose equivalent rates at 2 cm away from the patient′s neck and at 1 m away from the body were measured by the robot designed for nuclear medicine ward. Kruskal-Wallis rank sum test and Mann-Whitney U test were used to analyze the data.@*Results@#Neck dose equivalent rates for patients with RAT at different time points (4, 24, 48 and 72 h) after 131I administration were significantly different among 4 groups (H values: 20.889-46.410, all P<0.05), as well as the body dose equivalent rates (H values: 27.181-35.497, all P<0.05). The neck dose equivalent rates at 24, 48 and 72 h after 131I administration were statistically different between group 3 and 4 for patients with RMLT (z values: 2.328-3.076, all P<0.05; data in group 1 and 2 were too limited to be compared), while there was no statistical difference for the body dose equivalent rates (z values: 0.333-1.621, all P>0.05). The radioactivity retention in patients decreased rapidly within 24 h, then slowed down gradually and became extremely low at 72 h. At 72 h after 131I administration, 96.6%(255/264) patients with RAT and 100%(33/33) patients with RMLT were lower than 23.3 μSv/h, which meant the patients could be discharged from hospitalization.@*Conclusions@#Nuclear medicine ward service robots may dynamically measure residual radioactivity in DTC patients who take 131I treatment, providing individualized isolation solutions.
ABSTRACT
Objective To evaluate the residual radioactivity after 131 I treatment in postoperative in-patients with differentiated thyroid carcinoma ( DTC) using service robot in nuclear medicine ward, and as-sess the time for patients to be released from isolation. Methods From September 2017 to June 2018, 297 patients ( 94 males, 203 females, age:19-80 years) with DTC who underwent 131 I treatment after surgery were included. According to the purpose of treatment and the prescription dosage of 131 I, patients were divid-ed into 8 groups:4 groups accepted 131 I remnant ablation therapy ( RAT) with different dosages, which were 3700 MBq ( RAT1, n=34) , 4440 MBq ( RAT2, n=122) , 5550 MBq ( RAT3, n=81) and 7400 MBq ( RAT4, n=27) , respectively;4 groups had 131 I treatment for recurrent/metastatic lesions ( RMLT) , and the dosages were 3700 MBq ( n=1) , 4440 MBq ( n=2) , 5550 MBq ( n=14) and 7400 MBq ( n=16) . At 4, 24, 48 and 72 h after 131 I administration, the dose equivalent rates at 2 cm away from the patient's neck and at 1 m away from the body were measured by the robot designed for nuclear medicine ward. Kruskal-Wallis rank sum test and Mann-Whitney U test were used to analyze the data. Results Neck dose equivalent rates for patients with RAT at different time points ( 4, 24, 48 and 72 h) after 131 I administration were significantly different among 4 groups (H values:20.889-46.410, all P<0.05), as well as the body dose equivalent rates (H values:27.181-35.497, all P<0.05). The neck dose equivalent rates at 24, 48 and 72 h after 131 I administration were statistically different between group 3 and 4 for patients with RMLT ( z values:2.328-3.076, all P<0.05;data in group 1 and 2 were too limited to be compared) , while there was no statistical difference for the body dose equivalent rates (z values:0.333-1.621, all P>0.05). The radioactivity retention in patients decreased rapidly within 24 h, then slowed down gradually and became ex-tremely low at 72 h. At 72 h after 131I administration, 96.6％(255/264) patients with RAT and 100％(33/33) patients with RMLT were lower than 23.3 μSv/h, which meant the patients could be discharged from hospitalization. Conclusions Nuclear medicine ward service robots may dynamically measure residual radi-oactivity in DTC patients who take 131 I treatment, providing individualized isolation solutions.