Objective To prepare a domestically produced ⁶⁸Ge-⁶⁸Ga generator and compare it with an imported ⁶⁸Ge-⁶⁸Ga generator (ITG Company, Germany) for preliminary application evaluation.

Methods A ⁶⁸Ge-⁶⁸Ga generator was prepared, and the radioactivity of its elution product ⁶⁸Ga³⁺ was measured at the initial time (0) and 1, 4, and 12 h after elution. The γ-spectra of the elution product ⁶⁸Ga³⁺ and its distribution in normal mice were compared with those of an imported ⁶⁸Ge-⁶⁸Ga generator. The optimal labeling conditions for prostate-specific membrane antigen (PSMA)-11 labeled by domestic ⁶⁸Ge-⁶⁸Ga generator elution product and the radiochemical purity of the labeled product were determined, and the distribution of ⁶⁸Ga-PSMA-11 labeled by domestic and imported ⁶⁸Ge-⁶⁸Ga generator elution products in 22Rv1 prostate cancer tumor model mice was compared. The intergroup comparison of measurement data was conducted using the LSD method.

Results The radioactivity values of ⁶⁸Ga³⁺ in the elution product of the domestic ⁶⁸Ge-⁶⁸Ga generator at the initial time (0), 1, 4, and 12 h after elution were 125.8, 74.0, 118.4, and 111.0 MBq, respectively. The γ-spectra of ⁶⁸Ga³⁺ eluted by domestic and imported ⁶⁸Ge-⁶⁸Ga generators were highly consistent, and no difference was observed in the distribution of ⁶⁸Ga³⁺ in normal mice, and both showed high uptake of radioactivity in the heart. The optimal labeling conditions for PSMA-11 labeled by domestic ⁶⁸Ge-⁶⁸Ga generator elution product were pH 4.5, reaction at 85 ℃ for 15 min, and the radiochemical purity of the product ⁶⁸Ga-PSMA-11 was >95%. The imaging results of ⁶⁸Ga-PSMA-11 labeled by domestic and imported generator elution products in 22Rv1 prostate cancer model mice showed high uptake of ⁶⁸Ga-PSMA-11 at the tumor site, while the rest were mainly distributed in the kidneys and bladder. At 30, 60, and 90 min after injection, the radioactive uptake values of ⁶⁸Ga-PSMA-11 labeled by the domestic ⁶⁸Ge-⁶⁸Ga generator were lower than those of the imported ⁶⁸Ge-⁶⁸Ga generator ((3.60±0.14) %ID/g vs. (5.30±0.42) %ID/g, (3.40±0.12) %ID/g vs. (5.90±0.36) %ID/g, (2.90±0.28) %ID/g vs. (5.50±0.33) %ID/g). The differences were statistically significant (LSD method, all P<0.05).

Conclusion No significant difference was observed in the distribution of ⁶⁸Ga³⁺ and its labeled ⁶⁸Ga-PSMA-11 in normal mice and tumor model mice between the domestic ⁶⁸Ge-⁶⁸Ga generator and the imported ⁶⁸Ge-⁶⁸Ga generator.