The Evaluation of External Dose Rate Measurements of Patients During and After F-18 FDG PET/CT Imaging and Appropriate Discharge Time from PET/CT Department

Abstract

Introduction: F-18 radioisotope has higher photon energy when compared with other radioisotopes that are preferred in conventional imaging procedures in nuclear medicine. The aim of this study was to measure external radiation dose rate from patients injected with F-18 fluorodeoxyglucose (FDG) and to determine appropriate discharge time after F-18 FDG positron emission tomography/computed tomography (PET/CT) procedure. Methods: Our study included 29 (M/F=9/20) patients who were referred to nuclear medicine department for F-18 FDG PET/CT imaging. Dose rates were measured at a distance of 0, 0.5, 1, 1.5 and 2 m from patients via Geiger-Müller probe at 3 different time points: 1) Just after the intravenous injection of F-18 FDG, 2) before PET/CT imaging and 3) just before discharge of patients from PET/CT department. Statistical analysis was performed to evaluate the differences between measurements. Results: Patients were injected 291±62 megabecquerel (MBq) (range: 226-440 MBq) F-18 FDG via IV route. The patients stayed in nuclear medicine department for 70.3±13.8 min (range: 53 min-100 min) after injection of F-18 FDG. Radiation dose velocity measurements taken at a distance of 1 meter were 39.7±11.9 µSv/h just after the injection, 21.1±4.5 µSv/h before PET/CT examination and 14.3±2.9 µSv/h just before discharge. Conclusion: Although F-18 has high photon energy, its halflife is relatively short and this makes F-18 FDG an ideal radiopharmaceutical for PET/CT imaging. When the PET/CT scan is terminated, the dose rate measurements of the patients at a distance of 1 m are appropriate for discharge according to Turkish Atomic Energy Authority regulations. Therefore, patients can be safely discharged by explaining the necessary radiation safety measures after completing F-18 FDG PET/CT imaging.

The Nuclear Medicine Patient as a Line Source: The Source Length Is Certainly Not the Patient Height, But It Is a Reasonable Approximation

“…We retrieved 15 studies (Chiesa et al 1997; Cronin et al 1999; Benatar et al 2000; Pant and Senthamizhchelvan 2006; Gomes et al 2010; Demir et al 2011; Sudbrock 2011; Quinn 2012; Kim 2013; Yi 2013; Uhrhan 2014; Fayad et al 2015; Choi et al 2018; Al-Aamria et al 2019; Günes et al 2019) providing the required data; the number of patients per study was between 6 and 152. We defined two categories of measurement time: “immediate” and “1 h.” The first one is for measurements taken immediately after injection or maximum 15 min after injection, and the second one is for measurements taken between 50 min and 2 h after injection.…”

The potential advantages and workflow challenges of long axial field of viewPET/CT

“…ARPANSA regulates that patients should have less than 25 lSv/h measured at a distance of 1 m when leaving the facility, 32 the European Commission Radiation Protection asserts that patients should have less than 20 lSv/h, 33 while the United States recommends less than 50 lSv/h. 34 The recent literature finds that the general public is exposed to minimal radiation from discharged patients. The average estimated whole-body radiation dose rate 1 m away from a patient undergoing an 18 F-FDG whole-body scan was 20.4, 21.6, 21.0, 18.0 lSv/h for the neck, chest, abdomen and proximal thigh, respectively.…”

“…Examining and adjusting the radiation dose received by patients would also affect the radiation exposure of other allied medical workers and the general public passing through a PET/CT facility. ARPANSA regulates that patients should have less than 25 μSv/h measured at a distance of 1 m when leaving the facility, 32 the European Commission Radiation Protection asserts that patients should have less than 20 μSv/h, 33 while the United States recommends less than 50 μSv/h 34 …”

“…ARPANSA regulates that patients should have less than 25 μSv/h measured at a distance of 1 m when leaving the facility, 32 the European Commission Radiation Protection asserts that patients should have less than 20 μSv/h, 33 while the United States recommends less than 50 μSv/h. 34 …”

Radiation Sources and Doses of PET Center Staff and Patients

“…Так, в расчете на единицу активности введенного пациенту препарата 18 F-ФДГ она составляет (на расстоянии 1 м на уровне его груди) 0,055-0,150 мкЗв/МБк•ч [21], 0,147 мкЗв/МБк•ч [22], При этом мощность дозы этого источника непостоянна во времени и достаточно быстро снижается. Так, в работе [23] установлено, что при введении пациентам (n = 29) 18 F-ФДГ с активностью в диапазоне от 226 до 440 МБк средняя мощность дозы излучения «активного» пациента на расстоянии 1 м от него составляет 39,7±1,9 мкЗв/ч -сразу после инъекции, 21,1±4,5 мкЗв/ч -спустя 53-100 мин перед ПЭT/КT-исследованием и 14,3±2,9 мкЗв/ч -перед выходом пациента из ПЭТцентра. В работе [24] при ПЭТ-обследовании 50 «активных» пациентов показано, что в среднем мощность дозы за время пребывания в отделении снижается относительно равномерно с 27-30 мкЗв/ч до 8-9 мкЗв/ч.…”