Correlation between dose rate and physical factors of patients undergoing peptide receptor radionuclide therapy with (Lu-177)-DOTATATE

Abstract

In peptide receptor radionuclide therapy (PRRNT) for the treatment of neuroendocrine tumors with (Lu-177)-DOTATATE, large variations in dose rate at 1 m from the patient's body surface administered with same amount of Lu-177 activity are observed. The aim of this prospective study was to explain the cause of the variations and see if there is correlation between the dose rate per unit activity at 1 m distance from patient's body surface in PRRNT with (Lu-177)-DOTATATE and physical factors such as height, weight, age, body surface area (BSA), body mass index (BMI), height/weight (H/W) ratio, and BSA/BMI ratio. From this study, it is observed that dose rate per unit activity at 1 m distance from patient's body surface is significantly correlated with BMI, H/W ratio, and weight of the patients. Male and female patient's data were also separately analyzed, and there was no statistically significant difference observed in these groups of patients. As BMI or weight of the patient is increases, dose rate per unit activity at 1 m distance from patient's body surface decreases and as H/W ratio increases dose rate per unit activity at 1 m distance from patient's body surface also increases. Moderate correlation was seen with BSA and BSA/BMI ratio of the patients. No correlation was seen with age and height of the patients. From this study, H/W ratio can be considered as a good parameter for correlating the dose rate and activity retained in the patient's body. H/W ratio of patient affects the external dose measurement at 1 m from body surface immediately post-Lu-177 labeled PRRNT therapy. Thus, the study is important in formulating the regulatory criterion for discharge of patients after the treatment.