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

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 Lu-177-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 Lu-177-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.