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Showing 2 results for Pet Imaging
N. Amraee, Ph.d., B. Alirezapour, M. Hosntalab, A. Hadadi, H. Yousefnia,
Volume 21, Issue 3 (7-2023)
Abstract
Background: Due to the excellent physical and biochemical characteristics of 68Ga, 68Ga-1,4,7-triazacy–clononane–glutaric acid– 4,7 acetic acid- arginyl-glycyl-aspartic acid- bombesin (68Ga-NODAGA-RGD-BBN) was prepared as a new positron emission tomography (PET) imaging agent, and afterward, the preclinical evaluation of this labeled peptide was studied. Materials and Methods: 68Ga radioisotope was extracted from a 68Ge/68Ga generator with high radionuclide, chemical and radiochemical purities. Then; the 68Ga-NODAGA-RGD-BBN radiolabeled complex was prepared at optimized conditions. The stability of the complex was evaluated in phosphate-buffered saline (PBS) for at least 2 h. Cell studies of the radiolabeled peptide were also assessed on the gastrin releasing peptide receptor (GRPR)-expressing cell line. Finally; the biodistribution and whole-body scan imaging study of 68Ga-NODAGA-RGD-BBN was studied in normal and tumor-bearing mice. Results: The biodistribution and whole-body scan imaging of the radiolabeled compound on GRPR-expressing tumor-bearing mice demonstrated the high uptake in the tumor site at all post-injection intervals. The biodistribution results also demonstrated the major excretion route of the complex is the urinary tract. Conclusions: 68Ga-NODAGA-RGD-BBN shows high potential for PET imaging of patients with GRPR-expressing tumors; however, more biological studies are still needed.
F. Mohajeri, A. Ezzati, M. Studenski,
Volume 22, Issue 3 (7-2024)
Abstract
Background: 18-F fluoro-2-deoxy-D-glucose (18F-FDG) is the most common tracer in whole-body positron emission tomography (PET) imaging for cancer. The diagnostic information gained from a 18F-FDG is beneficial, but the administration of radioactive material always comes with an increased risk of secondary cancer. The objective of this paper was to calculate the effective dose for 18F-FDG injected patients considering the specific contribution from positron slowing down, positron annihilation, and electron capture mechanisms. Materials and Methods: The dose for various organs was estimated by using the Monte Carlo (MC) method. The Medical Internal Radiation Dose (MIRD) female phantom was used for the simulations and the effective doses to various organs from internal exposure from a 18F-FDG injection were calculated using a biokinetic model and International Commission on Radiological Protection (ICRP) publication 128 provided data. Calculated doses were compared with measured doses found in published studies. Results: The dose for each organ is dependent on the 18F decay mode. The total effective dose is 6.73 mSv when the administered activity is 185 MBq. Positron annihilation leads to the highest average effective dose at 3.57 mSv. The effective doses for positron slowing and electron capture gammas are 2.99 and 0.17 mSv, respectively. The urinary bladder, followed by the brain and heart, have the highest absorbed doses. The calculated doses for a female patient are in good agreement with published measured data. Conclusions: The results presented here can be used to scale the dose measured by a dosimeter to estimate the patient’s absorbed dose. Tracking the cumulative effective dose from medical procedures is an important aspect of managing the care of cancer patients to ensure regulatory limits are not exceeded.
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