TY - JOUR T1 - Image quality with low dose <sup>18</sup>F-FDG digital PET/CT: Preliminary results in 3 healthy volunteers JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 183 LP - 183 VL - 62 IS - supplement 1 AU - Ana Hurtado AU - Cristian Soza-Ried AU - Rodrigo Galaz AU - Andrea Rojas AU - Sandra Lopez AU - Horacio Amaral Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/62/supplement_1/183.abstract N2 - 183Introduction: 18F-FDG-positron emission tomography/computed tomography (PET/CT) allows qualitative and quantitative analysis of tumor lesions, and therefore, is highly demanded in oncology institutions. In many cases, patients require more than one PET/CT scan during the disease, increasing the radiation burden. Despite the constant improvement in PET/CT technology in the last years, the resolution and sensitivity of detectors can be better by replacing photomultipliers technology with photodiodes. Our work evaluates the new Siemens Biograph Vision performance, which has photodiodes (SiPM) in three healthy volunteers. We hypothesize that due to the better sensitivity, time of flight (TOF) of 214 ps, and smaller size of the crystal - photodiode assembly, allows smaller resolution with a shorter data acquisition time using fewer doses of injected activity. Methods: All participants signed an informed consent. For imaging, a digital PET/CT Vision was used. Three healthy volunteers were intravenously injected with 2‐deoxy‐2‐fluoro‐D‐glucose (18F‐FDG), corresponding to 1 MBq/kg (+/- 8%). The weight, uptake and glycemia were recorded in Table 1. Table 1: Measured parameters for all healthy volunteers. View this table: The data acquisition was obtained by 120 sec/bed position (s/bp) in list mode. Sinograms reconstruction was performed using 90 and 60 seconds, respectively. UltraHD PET (PSF+TOF), 4 iterations 5 subsets and pixel size 3.3 mm were used as reconstruction parameters for qualitative evaluation. Coefficient of Variation (COV), were evaluated in hepatic VOIs isocontour (41%) with all pass, and with 4 mm gaussian filter. Scan parameters configuration was adjusted to CT low dose Care kV and Caredose4D on. Exposure internal dose from 18F-FDG was estimated according to the ICRP 80. Results: All three volunteers were injected with 1 MBq/kg (+/- 8%) of 18F-FDG according to volunteers' sizes (Table 1). The injected dose of 18F-FDG was decreased by 80% in comparison to reported doses in guidelines. To evaluate the quality of 18F-FDG images, we measured the signal to noise ratio (SNR) on the three healthy volunteers' hepatic tissue. We use two reconstructed parameters with the standard protocol whole-body 18F-FDG were used. Our results showed that the image noise levels detected on the hepatic tissue were under the standards limits defined for PET/CT image acquisition and quantitative data analysis (Table 2). Likewise, the result obtained for 4 mm Gaussian filter using the following parameters: fixed UltraHD PET (Point Spread Function (PSF) + Time-of-flight (TOF)), 4 iterations 5 subsets, matrix size 220 x 220 and pixel size 3.3 mm, matched the expected value, and therefore, was established as the standard filter for 18F- FDG clinical protocols (Table 2). Our standard whole-body PET/CT protocol resulted in high image quality, as shown in figure 1. Furthermore, the image quality is maintained even when fewer acquisition times are used 90 and 60 seconds, respectively (Figure 2). Table 2: Quality images parameters obtained and exposure internal dose. View this table: B Figure 1. 18F-FDG Whole-body Low PET Dose. (A) shows subject 1 with all pass and with Gaussian filter 4 mm. (B) shows subject 3 with all pass and with Gaussian filter 4 mm. CBA Figure 2 18F-FDG Whole-body low PET dose multiple reconstruction times. (A, B and C) Case 1 with 120, 90 and 60 sec/bed respectively. Conclusions: Our preliminary data suggest that using digital PET/CT images, is it posible to decrease by 4 to 5 times the injected dose compared to published guidelines without deteriorating the image quality. Addiotionally, the less injected dose may have significant safety and economic advantages. For example, patients should be exposed to a low radiation dose, and radiopharmaceutical costs should be optimized. Our preliminary data indicate that implementing will allow us to implement new studies to demostrate this approach in pathological conditions with a significant increase in patients outcames. ER -