Comparison of Accuracy in Calculation of Absorbed Dose to the Kidneys Following Radioligand Therapy with ¹⁷⁷Lu-DKFZ-PSMA-617 by Two Different Background Correction Methods

Background: To improve the accuracy of activity image quality, scatter correction is a critical method. The aim of this study is to compare the accuracy in calculation of absorbed dose to patients following radioligand therapy (RLT) with ¹⁷⁷Lu-DKFZ-PSMA-617 by two different methods of background correction in the conjugate view method.

Materials and methods: This study involved 10 patients. The individualized patient dosimetry calculations were based on whole-body planar scintigraphy images acquired in 10 patients with a mean age of 71.4 ± 6.07 years (range 63-85 years) at approximately 0-2 h, 4-6 h, 18-24 h, and 36-48 h after administration of the mean 6253 ± 826.4 MBq (range 5500-7400 MBq) of ¹⁷⁷Lu-DKFZ-PSMA-617. Organ activities were calculated using the conjugate view method by Buijs and conventional background correction. Eventually, the absorbed dose of radiation was calculated using Medical Internal Radiation Dose formalism.

Results: The dose per unit of injected activity (mGy/MBq) ± standard deviation for kidney using Buijs and conventional methods was 1.05 ± 0.11 and 0.63 ± 0.14, respectively.

Conclusion: The Buijs background correction method was more accurate than the conventional method.