Development of a computer based program for estimation of radiation dose received by family members from neuroendocrine tumours patients treated with ¹⁷⁷Lu-DOTATATE

The last decade saw remarkable growth in the treatment of Neuroendocrine tumours (NETs) with radiolabelled peptides such as ¹⁷⁷Lu-DOTATATE. As per the regulations recommended in our country, this therapy can be given on an out-patient basis subject to the availability of dedicated ward with attached toilet for the patients (AERB/RSD/NM circular/2021/118). Radiological Safety Officer (RSO) of the facility must ensure that dose to the family members other than comforter does not exceed 1 mSv/y, prospectively estimated prior to discharge of the patient from the nuclear medicine department. The aim of this study was to develop a user-friendly computer- based program and estimate the dose received by family members from NETs patients treated with¹⁷⁷Lu-DOTATATE by using this computer program. A total of 55 patients suffering from metastatic NET and undergoing ¹⁷⁷Lu- DOTATATE treatment at our centre were cohorts of this study. These patients were administered a mean activity 6.73 ± 0.94 GBq (4.88 – 8.40 GBq) of ¹⁷⁷Lu-DOTATATE. After administration of ¹⁷⁷Lu-DOTATATE, a calibrated plastic scintillator detector- based instrument (Dosimeter AT1121, Atomtex) was used for dose rate measurements at 1 m distance from the centre of the patient's abdomen. These dose rate measurements were primarily performed prior to the patients first void post-administration. These dose rate measurements were analysed as a part of this study, to determine the dose received by the family members of the patients treated with ¹⁷⁷Lu-DOTATATE. Depending on the time spent by the relative near the patient, the likely effective doses to the family members was calculated using the equation. The mean dose rate obtained at 1m distance from the centre of patient's abdomen was 18.88 ± 3.42 μSv/h (Range: 11.2 - 26.5 μSv/h). The mean radiation dose received by the family members of the NET patients treated with ¹⁷⁷Lu-DOTATATE was 0.19 ± 0.03 mSv (0.11 - 0.26 mSv). The output data obtained by the program agrees with the manual calculation performed by using equation 1. The radiation dose received by the family members of NET patients treated with ¹⁷⁷Lu-DOTATATE is well below the limit prescribed by the competent authority. With the help of this computer-based program, it is easier and quick to predict the doses received by family members and accordingly the RSO can give the instructions to the patient and family members to be followed, after the discharge of the patient from the Nuclear Medicine department.