Spatial-temporal distribution characteristics and analysis of the peripheral dose equivalent rate around patients undergoing 68Ga-FAPI PET/CT

The peripheral dose equivalent rate decayed exponentially with time, with a decay constant λ of 0.74 h−1 at a distance of 1 m from the patient, resulting in an effective half-life of 56 min. Within 3 h after the injection of the radiopharmaceuticals, At 0.25 m, the dose rates was the highest at 0 h, reaching a normalized value of (68.05±5.94) μSv·h-1(100MBq)-1; it decreased to (15.61±1.86) μSv·h-1(100MBq)-1 at 3 h.

The effective doses received by the positioning technician, the family members contacted during the day, and the family members sleeping in the same bed at night were 0.40, 14.14, and 87.94 μSv per patient respectively. Conclusions The peripheral dose equivalent rate around patients undergoing 68Ga-FAPI PET/CT decreases rapidly with distance and time, and the public exposure level caused by patients to the surrounding personnel is lower than the effective dose constraint value stipulated by the national standard.