• Journal of radiological science and technology
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• v.21 no.2
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• pp.47-52
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• 1998

Tissue-equivalent $MgB_4O_7$ TL phosphors were prepared and the effects of Lantanides series activators on TLD properties of the phosphors were studied. The glow curve of TLD increased TL intensity and the peak temperature is low that is, the heating rate is $10^{\circ}C/sec$. The activation energy of the main peak estimated by the peak shape method. By these methods, the estimated activation energies were $0.76{\sim}1.55eV$ respectively. The TL phosphors prepared in this work may be utilized to radiation sensor elements because of this high sensitivity to X-ray.

• The Journal of the Korean dental association
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• v.50 no.7
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• pp.420-430
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• 2012

Purpose: The purpose of this study was to measure the absorbed dose and to calculate the effective dose for full-mouth periapical radiography using the portable dental x-ray machine and panoramic radiography Material and Method: Thermoluminescent chips were placed at 25sites throughout the layers of the head and neck of a tissue-equivalent human skull phantom. The man phantom was exposed with the portable dental x-ray machine and panoramic unit. During full-mouth periapical radiography the exposure setting was 60 kVp, 2 mA and 0.15 ~ 0.25 seconds, while during panoramic radiography the selected exposure setting was 72 kVp, 8 mA and 18 seconds. Absorbed dose measurements were obtained and equivalent doses to individual organs were summed using ICRP 103 to calculate of effective dose. Result: In the full-mouth periapical radiography, the highest absorbed dose was recorded at the mandible body follow with submandibular glands and cheek. Using panoramic unit, the highest absorbed dose was parotid glands and the following was back of neck and submandibular glands. The effective dose in full-mouth periapical radiography using portable dental x-ray machine was 46 ${\mu}Sv$. In panoramic radiography, the effective dose was 38 ${\mu}pSv$. Conclusion: It was recommended to panoramic radiography for general check in the head and neck area because that the effect dose in the panoramic radiography was lower than the dose in the full-mouth periapical radiography using portable dental x-ray machine.

• Imaging Science in Dentistry
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• v.42 no.2
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• pp.65-70
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• 2012

Purpose : The aim of this study was to compare the effective dose for imaging of mandible between multi-detector computed tomography (MDCT) and cone-beam computed tomography (CBCT). An MDCT with low dose technique was also compared with them. Materials and Methods : Thermoluminescent dosimeter (TLD) chips were placed at 25 organ sites of an anthropomorphic phantom. The mandible of the phantom was exposed using 2 different types of MDCT units (Somatom Sensation 10 for standard-dose MDCT, Somatom Emotion 6 for low-dose MDCT) and 3 different CBCT units (AZ3000CT, Implagraphy, and Kavo 3D eXaM). The radiation absorbed dose was measured and the effective dose was calculated according to the ICRP 2007 report. Results : The effective dose was the highest for Somatom Sensation 10 (425.84 ${\mu}Sv$), followed by AZ3000CT (332.4 ${\mu}Sv$), Somatom Emotion 6 (199.38 ${\mu}Sv$), and 3D eXaM (111.6 ${\mu}Sv$); it was the lowest for Implagraphy (83.09 ${\mu}Sv$). The CBCT showed significant variation in dose level with different device. Conclusion : The effective doses of MDCTs were not significantly different from those of CBCTs for imaging of mandible. The effective dose of MDCT could be markedly decreased by using the low-dose technique.

• Journal of Radiation Protection and Research
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• v.44 no.2
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• pp.79-88
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• 2019

Background: The main goal of experiments is to compare various operational and technical characteristics of D-Shuttle semiconductor personal dosimeters of the Japanese company "Chiyoda Technol Corporation" and Harshaw thermoluminescent dosimeters (TLD) manufactured by "Thermo Fisher Scientific" and DTL-02 of the Russian Research and Production Enterprise (RPE) "Doza" by their occupational and calibration exposure at various dose equivalents from 0.5 to 20 mSv of gamma-radiation. Materials and Methods: Besides dosimeters DTL-02, D-Shuttle and Harshaw TLD, there were also used: (1) the primary reference radionuclide source Hopewell Designs IAEA: G10-1-12 with $^{137}Cs$ isotope (an error is not more than 6% and activity is 20 Ci), and (2) the verification device UPGD-2M of RPE "Doza" and installed in the National Center for Expertise and Certification of the Republic of Kazakhstan (Kapchagai, the National Center for Expertise and Certification). Results and Discussion: The main results of researches are the following: (1) TLDs for Harshaw 6600 and DVG-02TM have an approximately equal measurement accuracy of the individual dose equivalents in the range from 0.5 to 20 mSv of gamma-radiation. (2) Advantages of dosimeters for Harshaw 6600 are due to the high measurement productivity and opportunity to indicate the dose on the skin $H_p$(0.07). Advantages of DVG-02TM consist of operation simplicity and lower cost than of Harshaw 6600. (3) D-Shuttles are convenient for use in the current and the operational monitoring of ionizing radiation. Measurement accuracy and 10% linearity of measurements are ensured when D-Shuttle is irradiated with dose equivalents below 1 mSv at the equivalent dose rate not higher than $3mSv{\cdot}hr^{-1}$. This allows using D-Shuttle at a routine technological activity. Conclusion: The obtained results of experiments demonstrate advantages and disadvantages of D-Shuttle semiconductor dosimeters in comparison with two TLD systems of DVG-02TM and Harshaw 6600.

• Progress in Medical Physics
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• v.20 no.3
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• pp.152-158
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• 2009

Total Skin Electron Beam Therapy (TSEBT) of linear accelerator has become use so as to be useful, 2~9 MeV of energy territories came to be used with mycosis fungoides and cutaneous lymphomas in the superficial lesion treatment which covers the major portion of the body. I treat a patient to Stanford technique in this study, and it is $60^{\circ}$ around the patients whom Stanford technique irradiated electronic beam to a linear accelerator in horizontal directions and there is a way a standard of TSEBT treat it to six located field (anterior, posterior, and four obliques) becoming. An each field does horizontally it and consist to beam of the two component which fitted the center to a suitable angle. a patient treats it to three dual field a day in order to make short treatment time. when a first day, we treat one dual field at anterior position and two dual field at posterior position. when the second day, treat one dual field at posterior position and two dual field at anterior position. Therefore, six dual field is finished in perfect periodic two days. we made cylindrical acrylic phantom, and I inserted a dosimeter film between phantom. in order to measure a dose distribution calculation before treat a patient, and a patient checked it in six field directions that got from a treatment. It is after that thermoluminescent dosimetry (TLD) as it uses Rando phantom and then measurement dose distribution in six field directions after attaching at chest, the right and left flank, a back after irradiation.

• Journal of Radiation Protection and Research
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• v.24 no.1
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• pp.39-43
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• 1999

Thermoluminescent (TL) response characteristics of a thin LiF:Mg,Cu,Na,Si Teflon detectors have been studied for use in beta radiation detection. The detectors were fabricated from a mixture of LiF:Mg,Cu,Na,Si phosphor and Teflon powder which was molded into a thin disk form of $50mg/cm^2$ thickness. These detectors were irradiated to beta fields of $^{147}Pm,\;^{204}Tl\;and\;^{90}Sr/^{90}Y$ sources with a covering of Kapton foil ($2mg/cm^2$) and photon irradiation was carried out with a $^{137}Cs$ source at the Korea Atomic Energy Research Institute (KAERI). Batch uniformity was estimated to be 4.7% and the beta dose response presented linear relationship from 0.1 mGy to 100 Gy. The beta energy responses of thin detectors normalized to $^{137}Cs$ were presented as 0.46, 1.09 and 1.06 for $^{147}Pm,\;^{204}Tl\;and\;^{90}Sr/^{90}Y$ beta rays, respectively. The evaluated values for angular responses were $0.93{\pm}0.03\;(^{147}Pm),\;0.94{\pm}0.04\;(^{204}Tl),\;and\;0.92{\pm}0.05\;(^{90}Sr/^{90}Y)$. The results satisfied well a proposed ISO Standard for beta ray dosimeters.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.150-153
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• 2002

High dose rate (HDR) brachytherapy in the treatment of cervix carcinoma has become popular, because it eliminated many of the problems with conventional brachytherapy. In order to improve clinical effectiveness with HDR brachytherapy, dose calculation algorithm, optimization procedures, and image registrations should be verified by comparing the dose distributions from a planning computer and those from a humanoid phantom irradiated. Therefore, the humanoid phantom should be designed such that the dose distributions could be quantitatively evaluated by utilizing the dosimeters with high spatial resolution. Therefore, the small size of thermoluminescent dosimeter (TLD) chips with the dimension of 1/8" and film dosimetry with spatial resolution of <1mm used to measure the radiation dosages in the phantom. The humanoid phantom called a pelvic phantom is made of water and tissue-equivalent acrylic plates. In order to firmly hold the HDR applicators in the water phantom, the applicators are inserted into the grooves of the applicator supporters. The dose distributions around the applicators, such as Point A and B, can be measured by placing a series of TLD chips (TLD-to- TLD distance: 5mm) in three TLD holders, and placing three verification films in orthogonal planes.

• Imaging Science in Dentistry
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• v.38 no.1
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• pp.7-15
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• 2008

Purpose: This study provides comparative measurements of absorbed and effective doses for newly developed cone beam computed tomography (CT) in comparison with these doses for conventional CT. Materials and Methods: Thermoluminescent dosimeter rods (TLD rod: GR-200, Thermo Fisher Scientific Inc., Waltham, MA, USA) were placed at 25 sites throughout the layers of Male ART Head and Neck Phantom (Radiology Support Devices Inc., Long Beach, USA) for dosimetry. Implagraphy, DCT Pro (Vatech Co., Hwasung, Korea) units, SCT-6800TXL (Shimadzu Corp., Kyoto, Japan), and Crane x 3+(Soredex Orion Corp., Helsinki, Finland) were used for radiation exposures. Absorption doses were measured with Harshaw 3500TLD reader (Thermo Fisher Scientific Inc., Waltham, MA, USA). Radiation weighted doses and effective doses were measured and calculated by 2005 ICRP tissue weighting factors. Results: Absorbed doses in Rt. submandibular gland were 110.57 mGy for SCT 6800TXL (Implant), 24.56 mGy for SCT 6800TXL (3D), 22.39 mGy for Implagraphy 3, 7.19 mGy for DCT Pro, 5.96 mGy for Implagraphy 1, 0.70 mGy for Cranex 3+. Effective doses $(E_{2005draft)$ were 2.551 mSv for SCT 6800TXL (Implant), 1.272 mSv for SCT 6800TXL (3D), 0.598 mSv for Implagraphy 3, 0.428 mSv for DCT Pro and 0.146 mSv for Implagraphy 1. These are 108.6, 54.1, 25.5, 18.2 and 6.2 times greater than panoramic examination (Cranex 3+) doses (0.023mSv). Conclusion: Cone beam CT machines recently developed in Korea, showed lower effective doses than conventional CT. Cone beam CT provides a lower dose and cost alternative to conventional CT, promising to revolutionize the practice of oral and maxillofacial radiology.

• Journal of Radiation Protection and Research
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• v.15 no.2
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• pp.57-65
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• 1990

Newly developed LiF(Mg, Cu, Na, Si) thermoluminescence phosphors sealed in a plastic capsules (32mm dia., 0.9mm wall thickness) were used for in-phantom dosimetry of $^{60}Co$ $\gamma$-irradiation. The absorbed doses in water were determined by applying the general cavity theory to the absorbed dose in TLD cavity, which was computed from exposure. The absorbed doses at various sites in the water-phantom were measured by LiF(Mg, Cu, Na, Si) TLD and compared with doses obtained by the ionization method. Both results were consistent within the experimental fluctuation$({\pm}3%)$ Central axis percentage depth doses and phantom-air ratios measured by LiF(Mg. Cu, Na, Si) TLD showed good agreement with the published values[Br. J. Radiology, Suppl. 17(1983)].

• Progress in Medical Physics
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• v.14 no.1
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• pp.15-19
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• 2003

High dose rate (HDR) brachytherapy for treating a cervix carcinoma has become popular, because it eliminates many of the problems associated with conventional brachytherapy. In order to improve the clinical effectiveness with HDR brachytherapy, a dose calculation algorithm, optimization procedures, and image registrations need to be verified by comparing the dose distributions from a planning computer and those from a phantom. In this study, the phantom was fabricated in order to verify the absolute doses and the relative dose distributions. The measured doses from the phantom were then compared with the treatment planning system for the dose verification. The phantom needs to be designed such that the dose distributions can be quantitatively evaluated by utilizing the dosimeters with a high spatial resolution. Therefore, the small size of the thermoluminescent dosimeter (TLD) chips with a dimension of <1/8"and film dosimetry with a spatial resolution of <1mm used to measure the radiation dosages in the phantom. The phantom called a pelvic phantom was made from water and the tissue-equivalent acrylic plates. In order to firmly hold the HDR applicators in the water phantom, the applicators were inserted into the grooves of the applicator holder. The dose distributions around the applicators, such as Point A and B, were measured by placing a series of TLD chips (TLD-to-TLD distance: 5mm) in the three TLD holders, and placing three verification films in the orthogonal planes. This study used a Nucletron Plato treatment planning system and a Microselectron Ir-192 source unit. The results showed good agreement between the treatment plan and measurement. The comparisons of the absolute dose showed agreement within $\pm$4.0 % of the dose at point A and B, and the bladder and rectum point. In addition, the relative dose distributions by film dosimetry and those calculated by the planning computer show good agreement. This pelvic phantom could be a useful to verify the dose calculation algorithm and the accuracy of the image localization algorithm in the high dose rate (HDR) planning computer. The dose verification with film dosimetry and TLD as quality assurance (QA) tools are currently being undertaken in the Catholic University, Seoul, Korea.