Implementation of dosimetry protocol for radionuclide therapy in Indonesia: Collaborative works in nuclear medicine

Abstract

The most application of Radionuclide Therapy (RNT) in Indonesia is Radio-iodine Therapy. However, recently, it has been extended to the application of 177Lu for prostate cancer (pCa) patients using PSMA and DOTATATE for radioiodine refractory differentiated thyroid cancer (RrDTC) patients. With support from the Coordinated Research Project from the International Atomic Energy Agency (CRP-IAEA), the establishment of the dosimetry protocol for Radionuclide Therapy is on progress. This article aimed to review the methodology and other aspects of the development of dosimetry protocol for Radionuclide Therapy in Indonesia. Eleven prostate cancer patients (pCa) (M, age between 57-75 years old), and eight RrDTC patients (5M, 3F, age between 47-71 years old.), have inclusively involved in pre-therapy dosimetry studies. About 170 MBq of RNT was injected to the patients. For the RrTC patients, the amino acid infusion protocol was performed for protecting the kidney before the administration of 177Lu-DOTATATE. Both patient groups were scanned with the Symbia T2 Siemens Gamma Camera with a scanning speed of 10 cm/min using a dual-head gamma camera equipped with a medium energy parallel hole collimator, with the dual peak settings at 113 and 208 keV and a 15% window setting for the acquisition of anterior and posterior whole-body scan (WBS). The images were quantified and analyzed by the view conjugate method, which has been taken at 1, 24, 48, and 72 hours after the administration. The result of the analysis was in mCi or MBq of activity in organs. With additional factors such as attenuation and calibration, the value has been calculated to the administered dose to get %ID and was used as the input of OLINDA/EXM to get the organ doses in mSv/MBq. The result of dose estimation in either PCa or RrDTC has shown that both kidneys and liver are the organs, which has the highest doses, but still safe and will receive not more than 2 Gy for 3.7GBq injection of 177Lu. To conclude, the implementation of dosimetry protocol using view conjugate method and continued by fitting with OLINDA/EXM for pretherapy dosimetry using 177Lu-PSMA and 177Lu-DOTATATE have been done through a collaborative project. The result of this work shows that kidneys and liver in both studies are safe and not exceed the organ dose limit. The protocol might be used to implement the dosimetry protocol in radionuclide therapy using 177Lu in Indonesia.