• Journal of Radiation Protection and Research
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• v.48 no.4
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• pp.197-203
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• 2023

Background: The thermoluminescent dosimeter (TLD) and Monte Carlo (MC) dosimetry are carried out to determine the occupational dose for personnel in the handling of ¹²⁵I seed sources. Materials and Methods: TLDs were placed in different layers of the Alderson-Rando phantom in the thyroid, lung and also eyes and skin surface. An ¹²⁵I seed source was prepared and its activity was measured using a dose calibrator and was placed at two distances of 20 and 50 cm from the Alderson-Rando phantom. In addition, the Monte Carlo N-Particle Extended (MCNPX 2.6.0) code and a computational phantom with a lattice-based geometry were used for organ dose calculations. Results and Discussion: The comparison of TLD and MC results in the thyroid and lung is consistent. Although the relative difference of MC dosimetry to TLD for the eyes was between 4% and 13% and for the skin between 19% and 23%, because of the existence of a higher uncertainty regarding TLD positioning in the eye and skin, these inaccuracies can also be acceptable. The isodose distribution was calculated in the cross-section of the head phantom when the ¹²⁵I seed was at two distances of 20 and 50 cm and it showed that the greatest dose reduction was observed for the eyes, skin, thyroid, and lungs, respectively. The results of MC dosimetry indicated that for near the head positions (distance of 20 cm) the absorbed dose rates for the eye lens, eye and skin were 78.1±2.3, 59.0±1.8, and 10.7±0.7 µGy/mCi/hr, respectively. Furthermore, we found that a 30 cm displacement for the ¹²⁵I seed reduced the eye and skin doses by at least 3- and 2-fold, respectively. Conclusion: Using a computational phantom to monitor the dose to the sensitive organs (eye and skin) for personnel involved in the handling of ¹²⁵I seed sources can be an accurate and inexpensive method.

• 대한방사선방어학회:학술대회논문집
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• 2009.11a
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• pp.146-147
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• 2009

• Proceedings of the Korean Society of Radiological Science
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• 1999.10a
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• pp.75.1-75.1
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• 1999

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.12-12
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• 2006

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.290-291
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• 2009

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.387-389
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• 1999

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.233-233
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• 1999

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.324-324
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• 1998

• Imaging Science in Dentistry
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• v.30 no.1
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• pp.11-15
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• 2000

Purpose: The primary objective of this study was to estimate the radiation absorbed doses in certain critical organs in the head and neck region with an Orthopos plus, a Panelipse, and a Panex-E machines. The second objective was to compare the absorbed doses between 5 inch by 12 inch and 6 inch by 12 inch image field for the Orthopos plus. Materials and Methods: Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses were measured at the thyroid gland, the submandibular gland, the parotid gland, the mouth floor, the maxillary sinus, the brain, the mandibular body, the mandibular ramus, the 2nd cervical spine and the skin over TMJ area. Results: The highest absorbed dose value was recorded at the mandibular ramus for the Orthopos plus with narrow image field. Higher absorbed dose values were recorded at the parotid gland, the mouth floor, the submandibular gland, and the 2nd cervical spine. The doses in the parotid gland were 597 μGy and 529 μGy with Orthopos plus, 638 μGy with Panelipse, and 1094μGy with Panex-E. Corresponding figures for the mandibular ramus were 2363 Gy and 1220 μGy, 248 μGy, and 118 μGy. The absorbed doses to the thyroid gland, the maxillary sinus, the brain, and the skin over TMJ were very low. Conclusion: Higher exposure values were recorded for the Orthopos plus than Panelipse and Panex-E. There was no significant differences of the absorbed doses according to the image field size.

• Journal of radiological science and technology
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• v.22 no.1
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• pp.55-60
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• 1999

In this study, the highly sensitive $CaSO_4:Tb$ glass capsule type TLDs are fabricated and their trap parameters are determined. The optimum conditions of fabricating of $CaSO_4:Tb$ phosphor was obtained to be in impurity concentration of Tb 1.0 mol% and sintering of $600^{\circ}C$, 2 hr. The glow curve of $CaSO_4:Tb$ consists of three glow peaks and these peaks are isolated by thermal bleaching method. Activation energy of the three glow peaks measured by the initial rise, the peak shape and the heating rate method are 0.70, 0.87, and 1.03 eV. The frequency factors are $1.76{\times}10^9,\;1.74{\times}10^9$, and $9.77{\times}10^8\;s^{-1}$, and the kinetic orders are 1.12, 1.46, and 1.34, respectively. The isolated glow peaks are fitted by least square method and optimum temperature range of the main peak for radiation dosimetry is $230{\sim}295^{\circ}C$.