Search

Highlights • The paper focuses on the dosimetry in nuclear medicine. • The personal dose equivalent H p (0.07) in workers handling 99mTc isotopes was analysed. • Correction coefficients for fingertips when using a wrist dosimeter was developed. • A wrist dosimeter can be used to measure the values of H p (0.07) for fingertips. Abstract Purpose Individual dosimetry is undoubtedly one of the best methods of assessing the exposure of personnel to ionizing radiation, however in case of nuclear medicine, the method applied to measure the dose does not always present a picture of the worker's actual exposure. The highly non-homogeneous dose distribution on the hand means that the ring dosimeter, routinely used to measure the H p (0.07), provides only approximate dose values received by fingertips, the body part most exposed to ionizing radiation. This paper is an attempt to answer the question whether the wrist dosimeter used as a replacement for the ring dosimeter is able to provide information on doses for the most exposed fragments of the hand of an employee during handling procedures with the use of radiopharmaceuticals. Materials Throughout measurements performed in five nuclear medicine facilities, high-sensitivity thermoluminescent detectors were used. Results Correction coefficients have been determined, which constitute an amendment to be made to move from the dose recorded by the wrist dosimeter to the doses received by the most exposed hand fragments. The fingertips received on average 25 times higher doses, compared to the values recorded by the wrist dosimeter. Conclusions A wrist dosimeter can be used to measure the H p (0.07) in nuclear medicine, including as a gauge of the most exposed parts of the hand – the fingertips. However, the applicability of correction coefficients makes it necessary to ensure a stable position of the wrist dosimeter during routine procedures. [ABSTRACT FROM AUTHOR]

The production of the 18F isotope—the marker of deoxyglucose (18F-FDG)—the radiopharmaceutical most commonly used in the oncological diagnostic technique of positron emission tomography, requires a cyclotron device. At present, there are nine facilities working in Poland that are equipped with cyclotrons used for producing the short-lived isotopes. The aim of the paper is to determine the hand exposure of workers employed in the two 18F-FDG production centres taking in to account the production procedures and work system in those facilities. Measurements, which included all professional workers exposed to ionizing radiation that were employed in two facilities, were performed by using high-sensitivity thermoluminescent detectors during the routine activities of the personnel. The work system used at the production centre has an impact on the level of the recorded doses. Among the production procedures performed by the staff, the highest ionizing radiation doses have been received by the staff during the 18F-FDG quality control. The maximum estimated annual Hp(0.07) for chemists from the quality control department can exceed the annual skin limit dose (500 mSv). The source of lowest doses on the hands are the cyclotron operating procedure and the 18F-FDG production, provided that these procedures can’t be combined with other production procedures. [ABSTRACT FROM AUTHOR]

It is important to optimize digital radiographic technique settings for small animal imaging in order to maximize image quality while minimizing radiation exposure to personnel. The purpose of this study was to evaluate two objective methods for determining optimal k Vp values for an indirect flat panel digital detector. One method considered both image quality and personnel exposure as endpoints and one considered only image quality. Phantoms simulated veterinary patients of varying thicknesses with lesions of varying sizes. Phantoms were exposed to a range of kVp values (60, 81, 100, and 121), using different mAs settings for each phantom. Additionally, all phantoms were exposed to a standard test exposure of 100 k Vp/2.5 m As. Scattered radiation was recorded and used as a measure of personnel exposure. When personnel exposure was considered, a figure of merit was calculated as an endpoint of optimization. The optimal k Vp value for each phantom was determined based on the highest signal difference-to-noise ratio with or without inclusion of the figure of merit. When personnel exposure was not considered, increasing k Vp resulted in higher signal difference-to-noise ratios and personnel exposure increased when both patient thickness and k Vp increased. Findings indicated that a single standard technique of 100 k Vp/2.5 m As was only optimal for most medium-sized patients. Images of thinner patients should be made with a lower k Vp. Very large patients require a higher k Vp than 100 regardless of the optimization method used. Personnel exposure from optimized techniques was low and not expected to exceed annual occupational dose limits. [ABSTRACT FROM AUTHOR]

The safety of workers and the public has been one of the most important concerns for electric utilities in the past and will continue to be so in the restructured electricity market. In this connection, Hydro One has assessed a number of methodologies for quantifying safety risks associated with the catastrophic failures of transmission station or substation equipment. This paper describes the assessment and its findings including the following: the study assessment methodology, data required, results obtained for some selected station equipment and study recommendations. [ABSTRACT FROM AUTHOR]

The use of 192Ir brachytherapy for the treatment of in-stent restenosis of the coronary arteries has shown promising clinical results. This paper investigates the radiation exposure of catheterization laboratory staff associated with the performance of this procedure. Methods and Materials: Cath lab staff were monitored using personal monitors (shielded against fluoroscopic x-rays) during the performance of eleven cases using nominal 10 GBq 192Ir sources. Staff positions in the lab were simultaneously tracked by video cameras. Direct measurements were also made using a survey meter. Treatments were administered in a conventional cardiac- catheterization-laboratory. Results: The dosimeter readings were analyzed in combination with the radiation survey and time motion survey. Brachytherapy procedural times for the cardiologist, oncologist, physicist, and angiographic assistants were, respectively, 26 +/- 24, 401 +/- 132, 486 +/- 148, and 7 +/- 13 s per case (mean +/- standard deviation). Readings ofthe personnel monitors were low. Credible upper limits of the respective doses are estimated to be less than 10, 10, 7, and 5 Mu Sv per procedure. Auxiliary shields reduced the dose to individuals located outside of the catheterization laboratory to less than 0.5 Mu Sv per procedure. Conclusions: The average radiation dose received by laboratory personnel during a representative 192Ir endocoronary brachytherapy procedure is estimated to be less than 0.1 % of the NCRPrecommended annual radiation worker's Maximum Permissible Dose (1%0 of the general public's MPD). This level is justifiable as long as the use of 192Ir benefits patients by producing an improved clinical outcome relative to the use of a less penetrating radionuclide or the application of alternative therapies. Further optimization of the delivery procedure is expected to reduce staff dose. [ABSTRACT FROM AUTHOR]