Objectives: Vascular and interventional radiology procedures are characterized by high exposure of personnel to ionizing radiation. This study assessed the exposure of medical personnel to ionizing radiation during vascular radiology and mechanical thrombectomy procedures. Material and...
During the production of 18F, as a result of the interaction of the beam of protons and secondary neutrons with the structural elements of the target body, many radionuclide impurities are created in the cyclotron. As part of this work, we theoretically predicted which isotopes would be activated in the target tantalum or silver bodies. Subsequently, we used gamma spectrometry analysis to verify these predictions. The results were compared with the work of other authors who studied titanium and niobium as materials for making the target body. Tantalum has been evaluated as the most favorable in terms of generating radionuclide impurities during the production of 18F by irradiation of 18O-enriched water in accelerated proton cyclotrons. Only three radionuclides were identified in the tested samples: 181W, 181Hf, and 182Ta with a half-life of fewer than 120 days. The remaining reactions led to the formation of stable isotopes.
1 April 2021 in Journal of Hazardous, Toxic, and Radioactive Waste
The production and use of radioactive tracers for positron emission tomography (PET) diagnostics in Poland generates various kinds of solid radioactive waste, the disposal of which requires special procedures. This study analyzes the replaceable elements of a medical cyclotron (i.e., a Havarfilm used for 18F- and 11C-label production). Nine samples were taken from the cyclotron between 2014 and 2016. In all of them, the quality and quantity of radioactive isotopes were analyzed. All samples of the Havar window were classified as high-activity radioactive waste, and after a time of cooling to reach medium level, a radioactive waste protocol was proposed. Storage of the waste materials in a selected room (e.g., in lead shields in a bunker at a medical center) enabled reduction of transportation and transfer costs to a radioactive waste disposal plant.
18 October 2023 in Nuclear Engineering and Technology
Quality control in mammography is a very important element. One of the parameters indicating the appropriate image quality is the threshold image contrast. The CDMAM phantom is used to measure this parameter. It is currently available in two versions 3.4 and 4.0. The aim of this work is to compare the threshold image contrast readings obtained with the CDMAM 3.4 and CDMAM 4.0 phantoms. In the measurements, 9 CDMAM 4.0 phantoms were used to check the difference in indications of individual copies. The phantom whose readings were closest to the average of all readings was used for comparative measurements with the CDMAM 3.4 phantom. Measurements were made on 40 mammography devices. The obtained images were read with the software provided by the phantom manufacturer and the CDMAM Analysis v2.3.0 (NCCPM) software. The average percentage difference between the minimum and maximum values indicated by the CDMAM 4.0 phantoms was 10.09%. Using the CDMAM Analysis v2.3.0 (NCCPM) software, the average difference in readings between the CDMAM 3.4 and CDMAM 4.0 phantoms is 7.93%, and when using the software provided by the phantom manufacturer, it is as much as 60.15%. The obtained results of the threshold image contrast are affected by the type of software used for reading and the accuracy of the execution of individual elements of the phantom. It is recommended to use CDMAM Analysis v2.3.0 (NCCPM) software or the latest software provided by the phantom manufacturer to read the phantom images.
This study investigates neutron radiation sources in medical cyclotrons used for PET isotope production, focusing on differences between 18F and 11C. Neutron and gamma dose rates were measured in the bunker and operator control room during routine production with an 11 MeV Eclipse cyclotron. 18F production generated approximately 2.5 times higher neutron levels in the bunker than 11C. Shielding performance also varied: the same wall reduced neutron fluxes by factors of kF = 14,000 for 18F and kC = 86,000 for 11C, while gamma shielding was similar for both isotopes (kγ ≈ 28,000). However, the neutron shielding factor calculated from the data for 18F should be taken as kF ≥ 1.4 × 104, because several neutron readings reached the upper limit of the detector range, which indicates a partial underestimation of the dose in the bunker. Consequently, neutron levels in the control room during 18F production were about 15-fold higher than during 11C production. These differences result from distinct neutron generation mechanisms. The 18O(p,n)18F reaction produces primary neutrons with a Maxwellian spectrum (~2.5 MeV), while 11C neutrons arise solely from secondary interactions in structural materials. The findings emphasize the need for composite shielding adapted to isotope-specific spectra. Annual dose estimates (260 18F and 52 11C productions) showed neutron exposure (3.78 mSv/year, 57%) exceeded gamma exposure (2.82 mSv/year, 43%). The total dose of 6.6 mSv/year is ~33% of regulatory limits, supporting compliance but underscoring the need for dedicated neutron dosimetry.