Production Of Short-lived Radionuclides Research Articles

A Radiation Levels Measurement at Workplace of Cyclotron-PET/CT Facilities (in Karachi) using TLD Dosimeters

Cyclotron is the most widely used proton particle accelerator for production of short lived radionuclides particularly F-18 for diagnostic purpose in oncology imaging. Currently, only Fluorine [F-18] is being produced in Pakistan. F-18 is tagged with glucose analogue and converted into [18F] FDG (Fluorodeoxyglucose) by synthesis process. [18F] FDG emits positron and, via annihilation process, produces two gamma photons of 511keV energy, which is of great concern for occupational safety. Therefore, a study was carried out to assess the dose incurred by radiation workers working in controlled and supervised areas of cyclotron facility.
 In this study, the ten (10) calibrated Thermoluminescene dosimeters (TLD-100) were annealed and placed in different locations of four Cyclotron-PET/CT facilities for determination of dose in work area. In the selected cyclotron facilities, one out of four was unshielded cyclotron and other three were self-shielded. Ten (10) TLDs were placed in preselected controlled and supervised areas of facilities for the duration of 30 days. After four weeks of exposure, TLDs were removed and assessed on TLD reader for dose evaluation.
 The evaluated results of radiation levels from TLDs are in good agreement with the criteria for classification of areas as defined in Regulations on Radiation Protection (PAK/904). The measured doses of work area are well below the defined regulatory dose limits for controlled area (>6mSv/yr) as well as supervised area (>1mSv/yr) except in case of unshielded cyclotron vault. It is concluded that the facilities have implemented the requirement 27 of PNRA Regulations on Radiation Protection (PAK/904) and also have established strong radiation safety measures for minimization of occupational exposure.

The production of short-lived radionuclides by new non-rotating and rotating Wolf-Rayet model stars

Context.It has been speculated that WR winds may have contaminated the forming solar system, in particular with short-lived radionuclides (half-lives in the approximate y range) that are responsible for a class of isotopic anomalies found in some meteoritic materials.

Short-Lived Radionuclides in Meteorites: Constraints on Nebular Timescales for the Production of Solids

Variations in the abundances of short-lived radionuclides such as 26Al (τ1/2 ≈ 0.74 Ma) and 53Mn (τ1/2 ≈ 3.7 Ma) in meteoritic solids may be used to infer relative formation intervals of these solids in the nebula at precisions of less than 1 Ma. In a strict chronometric interpretation of the isotopic variations, whereby criteria such as spatial and temporal isotopic homogeneity and closed system isotopic evolution are met, solid formation occurred in the nebula for at least several million years. This is longer than some theoretical and astronomical estimates for the duration of the active nebula. The evidence for live 41Ca (τ1/2 ≈ 0.10 Ma) in meteoritic inclusions further indicates that the onset of solid formation occurred quite early, perhaps within a few hundred thousand years after the onset of the collapse of the sun's parent molecular cloud. Failure of the chronometric interpretation may arise for a variety of reasons, including but not limited to, the late, inhomogeneous injection of material from a nearby stellar source or the local production of short-lived radionuclides by an energetic particle irradiation, e. g., from T Tauri (X-wind) or galactic cosmic ray sources. Although some isotopic evidence exists that the criteria required for a strict chronometric interpretation are not met by each of the short-lived chronometers, there is no compelling reason to shorten the interval of solid formation in the nebula to less than 1 Ma.

Cyclotron targetry for medical radioisotope production

Solid, liquid and gas targets for the production of short lived radionuclides are described. The use of nuclear data for optimizing different parameters for the target are discussed. The use of elements with low melting point and poor thermal conductivity for solid targetry were also discussed.

Status Report on the Nirs-Chiba Isochronous Cyclotron Facility

A variable energy isochronous cyclotron has been installed for biomedical studies. Since the fall of 1975, the cyclotron has been used for the clinical trial of fast neutron therapy and the production of short-lived radionuclides. To improve the beam stability, a beam-phase stabilizer has been developed. Recently, a heavy ion source of self heated cathode PIG type has been developed and several kinds of ions have been successfully accelerated. The facility and some experiences in the application are also described.

The Production of Short-lived Radionuclides with Cyclotron

The Production of Short-lived Radionuclides with Cyclotron