No abstract

3'-Deoxy-3-[F]fluorothymidine, or [F]FLT, is a positron emission tomography (PET) tracer used in clinical studies for noninvasive assessment of proliferation activity in several types of cancer. Although the use of this PET tracer is expanding, to date, few studies concerning its dosimetry have been published. In this work, new [F]FLT dosimetry estimates are determined for human and mice using Monte Carlo simulations. Modern voxelized male and female phantoms and [F]FLT biokinetic data, both published by the ICRP, were used for simulations of human cases. For most human organs/tissues the absorbed doses were higher than those reported in ICRP Publication 128. An effective dose of 1.70E-02 mSv/MBq to the whole body was determined, which is 13.5% higher than the ICRP reference value. These new human dosimetry estimates obtained using more realistic human phantoms represent an advance in the knowledge of [F]FLT dosimetry. In addition, mice biokinetic data were obtained experimentally. These data and a previously developed voxelized mouse phantom were used for simulations of animal cases. Concerning animal dosimetry, absorbed doses for organs/tissues ranged from 4.47 ± 0.75 to 155.74 ± 59.36 mGy/MBq. The obtained set of organ/tissue radiation doses for healthy Swiss mice is a useful tool for application in animal experiment design.

18F-Fluoroestradiol ([18F]FES), an estrogen analog, is a radiopharmaceutical used in Positron Emission Tomography (PET) that allows evaluating the tumor cell receptor profile and the best therapy strategy, the staging, the prognosis and the response to therapy in several breast cancer cases. As there is not any pharmacopoeia’s monograph of [18F]FES to standardize its quality control criteria, this work presents a new HPLC’s method to perform the [18F]FES radiochemical purity. A liquid chromatograph was used with radioactivity and ultraviolet detectors. Three concentrations of fluoroestradiol standard solution were used along the test. Their retention time was compared to its relative radiolabelled analogue to confirm its identity. Several mobile phases with acetonitrile and two mobile phase flows were tested to optimize the runs. Peaks symmetry, retention time, theoretical plates and resolution were analyzed to choose the best conditions. The mean retention time of both standard Fluoroestradiol and [18F]FES solutions were the same, demonstrating that [18F]FES formulation did not interfere with [18F]FES analysis. The best conditions were 1.2 mL/min and isocratic 40% V/V acetonitrile in water, which gave [18F]FES peak resolution greater than 6 and symmetry factor of 1. Thus, the developed method is ready to be validated and implemented in [18F]FES quality control routine in CDTN/Brazil.

F]FLT production and the evaluation of its effect on radiochemical yield and product quality. The first eluent evaluated was water: ethanol (90:10, v/v), commercially available, and the second was NaCl 0.9% (saline): ethanol (92:8, v/v). The mean of the corrected radiochemical yields corresponded to 27% ± 7% for elution with water and ethanol and to 23% ± 3% for elution with saline and ethanol, which could indicate that the eluent solutions have similar elution strength. Besides, quality control results were in accordance with the requirements and demonstrated that there was no significant difference between both formulations. Considering that pharmaceutical preparations containing ethanol should be preferentially diluted with saline to avoid hemolysis, the eluent saline:ethanol (92:8, v/v)

Activimeters (or dose calibrators) are essential instruments to verify activity of radiopharmaceutical after production and also before the dose administration in humans or animals for molecular imaging. The efficiency and safety measurements depend on, beside other factors, constancy tests and quality assurance. Thereby, the aim of this work was to perform constancy tests and quality assurance in the activimeters of the UPPR/CDTN, based on the CNEN-NN 3.05 Brazilian standard and the manufacturer's manual. Physical inspection, auto zero, background check, camera voltage, data check and constancy test were done. In addition, accuracy and precision tests were performed using a set of standard certified radioactive sources (57Co, 133Ba and 137Cs), according to the CNEN NN 3.05 Brazilian standard. Linearity test was also performed to evaluate the response of the equipment in over the entire range of activities used in routine. The equipments are periodically submitted to the quality control tests and the results were compared. After performing the proposed tests it is possible to conclude that activimeters are in accordance with the requirements of the CNEN standard and manufacturer´s manual. A quality control checklist was prepared to guide users and to record the results of quality assurance testing to monitor the equipment performance. This initiative is part of the quality assurance program implemented at UPPR.

No abstract

No abstract

[18F]Fluoroestradiol ([18F]FES), an estrogen analog, may be used in Positron Emission Tomography (PET) for evaluation of the tumor cell receptor profile in a noninvasive way, which is an important factor for determining the therapy to be used, disease staging, prognosis and response to therapy in breast cancer. [18F]FES is a new radiopharmaceutical and does not have an official monograph in any pharmacopeia until now. Therefore, the objective of this work was the optimization of the [18F]FES automatic synthesis and the elaboration of an analytical protocol for final product analyses. Initially, the synthesis of [18F]FES was performed according to a modified commercial protocol, using a TracerLab MXFDG synthesis module specific for [18F]FES synthesis. New protocols for the physicochemical quality control assays of the radiopharmaceutical were developed, including pH, chemical purity, residual solvents, radiochemical identity and purity. Physicochemical and microbiological analysis were performed with the synthesized [18F]FES at different time points to evaluate its stability. The uncorrected synthesis yield was 18.37 ± 3.07 %. All Quality Control methodologies proved to be effective for the product. The physicochemical and microbiological results obtained in the stability study showed that [18F]FES is stable during 8 hours after its synthesis, even under stress conditions. At the end of the study, it was concluded that the [18F]FES complies with all specifications required for a radiopharmaceutical intended for diagnostic use.