• Progress in Medical Physics
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• v.17 no.4
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• pp.187-191
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• 2006

The purpose of this study was to measure the dose distribution from the moving phantom for the respiratory motion. The phantom for TLD measurement was designed and built for this study based on the multiple plates for placing TLD and film. The TLDs may be inserted at 3 mm intervals in each TLD plate. For the measurements, TLD plate was inserted into the phantom at 1.5 cm ($d_{max}$) depth, and phantom was allowed to move in SI directions in the range of 1 to 2 cm with 0.5 cm interval for 6 MV X-ray beams. Penumbra and FWHM were measured at both moving state and compared stationary. It was found that penumbra increased 0.71 cm at stationary and 2.10 cm at moving state in 2 cm movement, and that FWHM are 7.52 cm for stationary state and 7.02 cm for moving state (2 cm movement). In this study, film was used to compared with TLD results of measurements and simitar results were observed. Therefore, it is expected that TLD moving phantom may be useful for the treatment of tumors that move due to the respiratory motion.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.329-334
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• 2012

For the dosimetry of the radiation workers, film badge, Thermo Luminescent Dosimeter (TLD), and glass dosimeter are being used and recently, there is a growing trend of using Optically Stimulated Luminescence Dosimeter (OSLD) in the world. However, OSLD is only being applied some of the field in Korea and there has been almost no study made related to OSLD. Thus, the accumulated radiation dose of TLD and OSLD that have been most frequently used in the field was compared in the radiation workers of nuclear medicine and their working areasfor 3 months. As a result, the average surface dose showed 0.85 mSv difference with 1.27 mSv for TLD and 2.12 mSv for OSLD while having 0.73 mSv difference for the average depth dose with 1.33 mSv for TLD and 2.06 mSv for OSLD. The surface dose and depth dose of OSLD showed statistically significant result with higher measurement (p<0.05).

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.473-476
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• 2012

The PET-MRI which has been installed and being managed recently uses both magnetic field and radiation. Most radiation workers wear a thermoluminescenct dosimeter (TLD) as a personal radiation dosimeter, and the TLD is affected both by a magnetic field and radiation. In this research, the same amount of X-ray was applied to 36 TLDs, and the changes in the dose of the 32 TLDs exposed to magnetic field at the location where its intensity of the magnetic resonance imaging (MRI) was about 5000 Gauss for eight hours with one-hour unit and that of the four TLDs not exposed to magnetic field were compared and checked. The measurement result showed that exposure dose of the TLD attached to the MRI changed irregularly depending on the amount of exposure time. Therefore, the TLD whose amount of changes little in the environment of a MRI is demanded to be developed.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.21-28
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• 1988

Absorbed dose in water was analyzed by Burlin's general cavity theory for medium X-ray energy region (HVL : 0.29, 0.84, 1.60, 2.62mm Cu) using LiF : PTFE TL dosimeter(0.4 mm ${\times}\;{\phi}$ 12.5mm, hot-pressed LiF TLD-700) which was enclosed in lucite capsule. The absorbed dose rate at 5cm depth in water phantom was determined with measurement error of ${\pm}5%$. This result was compared to that of the ionization method, indirectly absolute measurement method, of which measurement error of ${\pm}2%$. The difference between these two results lies within measurement error of LiF : PTFE method. Therefore, the absorbed dose in water obtained by LiF: PTFE is reliable, and this result suggests the base to estimate dose-equivalent for medium X-rays.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.135-141
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• 1997

The study of anneal characteristics is important for TL dosimeter to reuse. To obtain the annealing condition of the recently developed, new TL dosimeter, LiF:Mg,Cu,Na,Si Teflon Tills in a disk type (diameter 4.5 mm, thickness about $90mg/cm^2$), we studied for pre-irradiation annealing, readout procedure and post-readout annealing, in order. The gamma irradiations were carried out with a $^{60}Co$, dose of 0.1 Gy. We have used the method that observe the variation of thermoluminescent(TL) intensity of these Teflon TLDs over repeated cycles by changing both anneal temperature and anneal time with the TLD reader and the oven. There is a 5% loss in sensitivity over the ten repeated readouts by the annealing condition:pre-irradiation annealing at $80^{\circ}C$ for one hour, readout to $280^{\circ}C$ and post-readout annealing at $270^{\circ}C$ for 20 seconds.

• Progress in Medical Physics
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• v.2 no.2
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• pp.149-154
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• 1991

We have designed and applied the calibrationmethod of $\^$90/Sr Ophthalmic Applicaton by measuring the electron currents. We considered the number of electrons which is emitted from the source, the area of the source, and the electron stopping power in the water, and those data were used for calculation. Film was used for evaluating the accurate source area. Average electron stopping power was obtained by analyzing ${\beta}$-ray energy spectrum. We compared between the result from our method and that from the TLD measurements. The calibration result from our method shows 63.3 ${\pm}$5.1 cGy/sec, while 50.7${\pm}$7.3 cGy/sec from TLD measurement. But the supplier's specification tells 46.89.4cGy/sec.

• 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.

• Progress in Medical Physics
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• v.18 no.3
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• pp.126-133
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• 2007

A head-and-neck phantom was designed in order to evaluate remotely the quality of the delivery dose of intensity modulated radiation therapy (IMRT) in each institution. The phantom is homogeneous or inhomogeneous by interchanging the phantom material with the substructure like an air or bone plug. Monte Carlo simulations were executed for one beam and three beams to the phantom and compared with ion chamber and thermoluminescent dosimeter (TLD) measurements of which readings were from two independent institutions. For single beam, the ion chamber results and the MC simulations agreed to within about 2% TLDs agreed with the MC results to within 2% or 7% according to which institution read the TLDs. For three beams, the ion chamber results showed -5% maximum discrepancy and those of TLDs were $+2{\sim}+3%$. The accuracy of the TLD leadings should be increased for the remote dose monitoring. MC simulations are a valuable tool to acquire the reliability of the measurements in developing a new phantom.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.1-7
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• 2005

High-quality single crystals of pure $Li_2B_4O_7$ as well as $Li_2B_4O_7$ doped with Cu, Mn and Mg impurities (1.0mol%, respectively) have been grown from the melt of $Li_2CO_3+2B_2O_3$ by Czochralski method in platinum crucibles. To study the thermoluminescent properties, $Li_2B_4O_7$ series single crystal TLDs were made by cutting in the size of $4{\times}5{\times}1\;mm^3$. The glow curves show two or three peaks which can be easily deconvoluted. It is observed that room temperature($20{\sim}30^{\circ}C$) fadings of the dosimetric peaks of $Li_2B_4O_7$ series single crystal TLDs were about 10 % for 30 days. The relative photon energy response for $Li_2B_4O_7$ series single crystal TLDs were about 85 % when the responses were normalized to that measured with $^{60}Co\;(1.25\;MeV)\;{\gamma}-rays$. The measured data are in a good agreement with theoretical ones. The $Li_2B_4O_7$ series single crystal TLDs fabricated in this work can be used for monitoring personal and environmental radioactivity.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.247-255
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• 2009

This study aims to provide basic data for establishing the safety and health plan by investigating the exposure conditions in the facilities registering business about handling radiations and radioactive isotopes in Korea. dose levels(working space, worker location) of the workers in 153 facilities were measured using surveymeter, and individual exposure concentration[(shallow dose(SD), depth dose(DD)] in 27 facilities using thermal luminescence dosimeter(TLD). In accordance with the measurement results by business type[fire fighting prevention business(FFPB, n=10), financial insurance business(FIB, n=3) and other facilities(n=140)] using surveymeter, those three business type groups showed difference (p<0.000). Dose levels of worker location for FFPB and FIB were significantly higher than 10.0 ${\mu}Sv$/hr, the allowable standard for radiations and radioactive isotopes, and they were higher 109.3 times(p<0.000) and 187.5 times(p<0.000) than those in other facilities. The concentration of TLD[FFPB(n=10), other facility (n=17)] in DD of FFPB was significantly higher than that in other facility(p=0.05). In accordance with the analysis result on relationship between surveymeter and TLD, the dose on working space and worker location(r=0.406, p<0.05), worker location dose and SD(r=0.453, p<0.05), worker location dose and DD(r=0.553, p<0.01), and SD and DD(r=0.927, p<0.001) had all related each other. It is urgently required to change FFPB and FIB from the facilities requiring registration for handling radiations and radioactive isotopes to the facilities that shall get permission for handling radiations and radioactive isotopes by reestablishing the legal administration area, for safety and health of radiation occupants.