The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Mats Isaksson - One of the best experts on this subject based on the ideXlab platform.
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A comparison between Monte Carlo-calculated and -measured total efficiencies and energy resolution for large plastic scintillators used in Whole-Body Counting.
Radiation protection dosimetry, 2010Co-Authors: Jenny Nilsson, Mats IsakssonAbstract:The measured total efficiency for several source positions has been determined for a large, plastic scintillation detector (NE 102A, 91.5 × 76.0 × 24.5 cm(3)) used for Whole-Body Counting gamma spectrometry. The results have been compared with Monte Carlo-calculated total efficiencies; the code used was MCNPX 2.60. For (137)Cs, there was a good agreement between the measured and calculated total efficiencies. MXNPX was also used to calculate the electron light yield for (137)Cs; for the detector material NE 102A, Birks' constant kB was found to be 9.6 mg cm(-2) MeV(-1). The effect of light losses on spectrum resolution has been investigated for (65)Zn.
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Determination of potassium in the skeletal muscles by Whole-Body Counting.
Acta Diabetologica, 2003Co-Authors: Mats Isaksson, I. Bosaeus, Y. Surać, M. AlpstenAbstract:Changes in muscular function are related to nutritional status, disease and physical activity. To study these relationships, it is desirable to be able to determine the Whole Body potassium content, which is characteristic to the muscular tissue. This can be achieved by measurements in a Whole-Body counter, identifying contributions from the upper and lower parts of the Body. In a Whole-Body counter with large plastic scintillators, a special measuring methodology is required. Such a method of measuring 40K in the leg muscles, extracting the part of the detector signal originating from the lower part of the Body, has been developed and tested by independent phantom measurements. The results suggest that it is suited to perform regional measurements of Body potassium but validation and implementation into clinical research are still necessary.
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Determination of the retention of 47Ca by Whole-Body Counting
Applied radiation and isotopes : including data instrumentation and methods for use in agriculture industry and medicine, 2000Co-Authors: Mats Isaksson, Kerstin Fredlund, Ann-sofie Sandberg, Anette Almgren, Lena Rossander-hulthénAbstract:Retention of intravenously or orally administered 47Ca in the human Body are described by a two-parameter function. It is then sufficient to make only a few Whole-Body measurements to determine the retention function, avoiding faeces sampling and stool markers. Seven days after intake the non-absorbed calcium was excreted and the model agreed with the measured relative retention. Absorption of calcium could then, in some cases (e.g. comparative studies), be described by relative retention at the 7th day after intake.
Ji Seok Kim - One of the best experts on this subject based on the ideXlab platform.
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Use of photographic images to construct voxel phantoms for use in Whole-Body Counting.
Radiation protection dosimetry, 2009Co-Authors: Ji Seok Kim, Jong Hwi Jeong, Kun Woo Cho, Jai Ki LeeAbstract:Quantification of radioactivity in the Body by in vivo bioassay uses Counting efficiencies obtained from calibration from a phantom. Usually a standardised BOMAB (Bottle Manikin Absorption) phantom is employed for Whole-Body Counting. The physical size of workers being counted, however, may differ from the calibration phantom, and can be a source of significant errors in dose estimates. A methodology was developed applying subject-specific efficiency data determined by Monte Carlo simulation based on a voxel phantom that was constructed from photographic images of the subject. This approach was demonstrated using a BOMAB phantom. The measured and calculated efficiencies agreed well, with maximum deviation of 30 % at 1.836 MeV (Y-88 gamma-rays). The expected Counting efficiencies for an obese volunteer appear higher compared with a BOMAB phantom. This is caused by a closer distance between the detector and the Body surface. The fast construction technique of voxel phantoms will contribute to a reduction in uncertainty caused by variations in the Counting geometry.
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A validation of computational phantoms from photographic images for patient-tailored Whole Body Counting
Applied Radiation and Isotopes, 2009Co-Authors: Ji Seok Kim, Jong Hwi Jeong, Kun Woo Cho, Jai Ki LeeAbstract:This study attempted to validate a new method for patient-tailored efficiency calibration. Digital calibration with Monte Carlo simulations was used to substitute the lack of precision limitation due to the limited number of experimental phantoms in Whole Body Counting calibration for internal dosimetry. The validity of this approach was examined by comparing the simulation results to the measured values from actual measurements using family BOMAB phantoms. The computational voxel phantoms were constructed by a reconstruction technique using AP and lateral photographic images of the BOMAB phantoms, instead of using the given specifications provided with BOMAB phantoms. Although discrepancies to a certain degree between the computational simulation and measured efficiencies do exist, the results support the new approach of being an alternative to family BOMAB phantoms.
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Simplified Calibration Method for the Transportable Whole Body Counting System in Radiation Accidents
Journal of Nuclear Science and Technology, 2008Co-Authors: Ji Seok Kim, Hyun Ki Kim, Chang Woon ChoiAbstract:A Whole Body counter is used for assessment of internal dose in the Body by directly measuring the radiation emitted from the Body. It is the most reliable and standard method of monitoring for internal exposure. National Radiation Emergency Medical Center in Korea Institute of Radiological and Medical Science constructed the transportable Whole Body Counting system with chair geometry. The system uses HPGe detector as in-vivo monitoring device. Good energy resolution of the system was obtained with the HPGe detector. Although chair geometry used in the system has poor uniformity of the detector response, it is more suitable than other geometries as transportable system for accidental monitoring of internal contamination. In this study, relative response of the single torso detector according to position of the detector was analyzed to determine Counting distance between subject and detector and to promote conventional calibration method for Whole Body Counting system. Activities in each part of the phant...
Matthew M. Mille - One of the best experts on this subject based on the ideXlab platform.
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An analysis of dependency of Counting efficiency on worker anatomy for in vivo measurements: Whole-Body Counting.
Physics in medicine and biology, 2008Co-Authors: Binquan Zhang, Matthew M. MilleAbstract:In vivo radiobioassay is integral to many health physics and radiological protection programs dealing with internal exposures. The Bottle Manikin Absorber (BOMAB) physical phantom has been widely used for Whole-Body Counting calibrations. However, the shape of BOMAB phantoms-a collection of plastic, cylindrical shells which contain no bones or internal organs-does not represent realistic human anatomy. Furthermore, workers who come in contact with radioactive materials have rather different Body shape and size. To date, there is a lack of understanding about how the Counting efficiency would change when the calibrated counter is applied to a worker with complicated internal organs or tissues. This paper presents a study on various in vivo Counting efficiencies obtained from Monte Carlo simulations of two BOMAB phantoms and three tomographic image-based models (VIP-Man, NORMAN and CNMAN) for a scenario involving homogeneous Whole-Body radioactivity contamination. The results reveal that a phantom's Counting efficiency is strongly dependent on the shape and size of a phantom. Contrary to what was expected, it was found that only small differences in efficiency were observed when the density and material composition of all internal organs and tissues of the tomographic phantoms were changed to water. The results of this study indicate that BOMAB phantoms with appropriately adjusted size and shape can be sufficient for Whole-Body Counting calibrations when the internal contamination is homogeneous.
Binquan Zhang - One of the best experts on this subject based on the ideXlab platform.
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An analysis of dependency of Counting efficiency on worker anatomy for in vivo measurements: Whole-Body Counting.
Physics in medicine and biology, 2008Co-Authors: Binquan Zhang, Matthew M. MilleAbstract:In vivo radiobioassay is integral to many health physics and radiological protection programs dealing with internal exposures. The Bottle Manikin Absorber (BOMAB) physical phantom has been widely used for Whole-Body Counting calibrations. However, the shape of BOMAB phantoms-a collection of plastic, cylindrical shells which contain no bones or internal organs-does not represent realistic human anatomy. Furthermore, workers who come in contact with radioactive materials have rather different Body shape and size. To date, there is a lack of understanding about how the Counting efficiency would change when the calibrated counter is applied to a worker with complicated internal organs or tissues. This paper presents a study on various in vivo Counting efficiencies obtained from Monte Carlo simulations of two BOMAB phantoms and three tomographic image-based models (VIP-Man, NORMAN and CNMAN) for a scenario involving homogeneous Whole-Body radioactivity contamination. The results reveal that a phantom's Counting efficiency is strongly dependent on the shape and size of a phantom. Contrary to what was expected, it was found that only small differences in efficiency were observed when the density and material composition of all internal organs and tissues of the tomographic phantoms were changed to water. The results of this study indicate that BOMAB phantoms with appropriately adjusted size and shape can be sufficient for Whole-Body Counting calibrations when the internal contamination is homogeneous.
Jai Ki Lee - One of the best experts on this subject based on the ideXlab platform.
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Use of photographic images to construct voxel phantoms for use in Whole-Body Counting.
Radiation protection dosimetry, 2009Co-Authors: Ji Seok Kim, Jong Hwi Jeong, Kun Woo Cho, Jai Ki LeeAbstract:Quantification of radioactivity in the Body by in vivo bioassay uses Counting efficiencies obtained from calibration from a phantom. Usually a standardised BOMAB (Bottle Manikin Absorption) phantom is employed for Whole-Body Counting. The physical size of workers being counted, however, may differ from the calibration phantom, and can be a source of significant errors in dose estimates. A methodology was developed applying subject-specific efficiency data determined by Monte Carlo simulation based on a voxel phantom that was constructed from photographic images of the subject. This approach was demonstrated using a BOMAB phantom. The measured and calculated efficiencies agreed well, with maximum deviation of 30 % at 1.836 MeV (Y-88 gamma-rays). The expected Counting efficiencies for an obese volunteer appear higher compared with a BOMAB phantom. This is caused by a closer distance between the detector and the Body surface. The fast construction technique of voxel phantoms will contribute to a reduction in uncertainty caused by variations in the Counting geometry.
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A validation of computational phantoms from photographic images for patient-tailored Whole Body Counting
Applied Radiation and Isotopes, 2009Co-Authors: Ji Seok Kim, Jong Hwi Jeong, Kun Woo Cho, Jai Ki LeeAbstract:This study attempted to validate a new method for patient-tailored efficiency calibration. Digital calibration with Monte Carlo simulations was used to substitute the lack of precision limitation due to the limited number of experimental phantoms in Whole Body Counting calibration for internal dosimetry. The validity of this approach was examined by comparing the simulation results to the measured values from actual measurements using family BOMAB phantoms. The computational voxel phantoms were constructed by a reconstruction technique using AP and lateral photographic images of the BOMAB phantoms, instead of using the given specifications provided with BOMAB phantoms. Although discrepancies to a certain degree between the computational simulation and measured efficiencies do exist, the results support the new approach of being an alternative to family BOMAB phantoms.
