319. Effective Dose Assessment on an Hybrid Equipment: Results and challenges to integrate with MDCT

Abstract

Purpose The aim of this study was to measure, monitor and report effective dose in nuclear medicine and to assess current challenges in integrating these measures with CT. Methods In 2014 we connected a CT-PET to a dose tracking software and started to collect dose data from CT modality; in late 2015 the software was upgraded to a version which includes a nuclear medicine module for dose tracking. Data from the PET part of the scanner, in terms of administered activity and effective dose, were also collected. Results Data from 12000 CT doses and 3700 PET doses were collected, mostly from: Whole Body (WB) 18F-FDG (63.2%), WB 11C-Choline (12.8%), WB 68Ga-DOTATOC (5.5%), Head 11C-Methionine for a total of 18.4% of the whole activity of the scanner. CT mean DLP (mGy∗cm) data values were (range between brackets): WB 18F-FDG 1486.3 (76.1-7700.9), WB 11C-Choline 2451.9 (290.9-5023.1), WB 68Ga-DOTATOC 1183.8 (41.0-3728.4) and Head 11C-Methionine 766.7 (52.3-2326.9). Mean effective doses (mSv) were: WB 18F-FDG 15.3 ± 4.7, WB 11C-Choline 26.5 ± 5.6, WB 68Ga 13.4 ± 3.7 and Head 11C-Methionine 1.2 ± 0.7. Mean administered activities (MBq) and effective doses (mSv) for radiopharmaceuticals used in PET were: WB 18F-FDG 335.9-6.4, Head 11C-Methionine 294.6-2.5, WB 68Ga-DOTATOC 168.3-3.5 and WB 11C-Choline 322.2–1.5. The mean total effective doses (mSv) due to both modality were: WB 18F-FDG 21.7 ± 4.9, Head 11C-Methionine 3.7 ± 0.8, WB 11 C-Choline 27.9 ± 5.6 and WB 68Ga-DOTATOC 16.9 ± 2.8. Conclusions The implementation of a dose tracking system to nuclear medicine is of great value for accurate and regular recording, reporting and analysis of patient’s effective doses. It can help to improve the evaluation of radiation exposures in the clinical practice.