• Title/Summary/Keyword: 전리조 선량계

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Effect of Automatic Exposure Control Marker with Chest Radiography in Radiation Reduction (자동노출제어를 사용한 X선 흉부촬영에서 AEC 표지자 사용에 따른 환자 피폭선량 감소 효과)

  • Jung, Ji-Sang;Choi, Byoung-Wook;Kim, Sung-Ho;Kim, Young-Mo;Shim, Ji-Na;Ahn, Ho-Sik;Jin, Duk-Eun;Lim, Jae-Sik;Kang, Sung-Ho
    • Journal of radiological science and technology
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    • v.37 no.3
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    • pp.177-185
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    • 2014
  • This study focused on effects of patient exposure dose reduction with AEC (Auto Exposure Control) marker that is designed for showing location of AEC in X-ray Chest radiography. It included 880 adults who have to use Chest X-ray Digital Radiography system (DRS, LISTEM, Korea). AEC (Ion chambers are posited in top of both sides) are used to every adult and set X-ray system as Field size $17{\times}17inch$, 120kVp, FFD 180cm. 440 people of control group are posited on detector to include both sides of lung field and the other 440 people of experimental group are set to contact their lung directly to Ion chamber (making marker to shows location). Then, measured every DAP and, estimated patient effective dose by using PCXMC 2.0. The average age of control group (M:F=245:195) is 53.9 and the average BMI is 23.4. BMI ranges from under weight: 35, normal range: 279, over weight: 106 to obese: 20 and average DAP is 223.56mGycm2, Mean effective dose is 0.045mSv. The average age of experimental group (M:F=197:243) is 53.7 and the average BMI is 22.7. BMI ranges from under weight: 34, normal range: 315, over weight: 85 to obese: 6 and average DAP is 207.36mGycm2, Mean effective dose is 0.041mSv. Experimental group shows less Mean effective dose as 0.004mSv (9.7%) than control group. Also, patient numbers who got over exposure more than 0.056mSv (limit point to know efficiency of AEC marker) is 65 in control group (14.7%), 19 in experimental group (4.3%) and take statistics with t-Test. The statistical difference between two groups is 0.006. In order to use proper amount of X-ray in auto exposure controlled chest X-ray system, matching location between ion chamber and body part is needed, and using AEC marker (designed for showing location of ion chamber) is a way to reduce unnecessary patient exposure dose.

Development and Radiation Shield effects of Dose Reduction Fiber for Scatter ray in CT Exams (피폭선량저감 섬유의 개발과 CT 검사시 산란선 차폐 효과)

  • Kim, Sunghwan;Kim, Yong Jin;Kwak, Jong Suk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.4
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    • pp.1871-1876
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    • 2013
  • In this study, we developed and characterized the shielding properties of dose reduction fiber (DRF, Buffalo Co.) sheet during brain and chest CT examinations. The DRF sheet was composed of $1{\sim}500{\mu}m$ oxide Bismuth ($Bi_2O_3$) and 5 ~ 50 nm nano-barium sulfate ($BaSO_4$). Phantom and clinical studies were performed for characterization of the DRF shielding properties. In clinical study, we measured doses of eye, chest, abdomen and reproductive system of 60 patients in 3 hospitals during brain and chest CT examinations. We could determined the shielding effect of the DRF by comparing the doses when we used the DRF sheet or not. When we used the sheet during CT examination, the scattered dose were reduced about 20~50%. So, we suggest that the fiber should be used in radiological examinations for reducing patients doses.

A study on Synthesis and Radiation Detector Fabrication of Thin Films by MW Plasma CVD (MWPECVD에 의한 박막의 합성과 방사선 검출 특성에 관한 연구)

  • Koo, Hyo-Geun;Lee, Duck-Kyu;Song, Jae-Heung;Noh, Kyung-Suk;Park, Sang-Hyun
    • Journal of radiological science and technology
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    • v.27 no.2
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    • pp.45-50
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    • 2004
  • Synthesis diamond films have been deposited on the molybdenum substrates using an microwave plasma enhanced chemical vapor deposition method. The effects of deposition time, surface morphology, infrared transmittance and Raman scattering have been studied. Diamond deposited on molybdenum substrate for 100 hours by MW plasma CVD from $CH_4-H_2-O_2$ gas mixture had good crystallity with $100[{\mu}m]$ thickness needed for radiation detector. Diamond radiation detector of M-I-M type was made and the current of radiation detector was increased by increasing X-ray dose.

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Evaluation of dose variation at the vertex during Total Skin Electron Beam (전신 피부 전자선 조사(TSEB)시 두정부(Vertex)에서의 선량 변화 평가)

  • Jeon Byeong-Chul;An Seung-Kwon;Lee Sang-Gyu;Kim Joo-Ho;Cho Kwang-Hwan;Cho Jung-Hee;Park Jae-Il
    • The Journal of Korean Society for Radiation Therapy
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    • v.12 no.1
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    • pp.112-116
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    • 2000
  • Purpose : The vertex scalp is always tangentially irradiated during total skin electron beam(TSEB) This study was discuss to the dose distribution at the vertex scalp and to evaluate the use of an electron reflector. positioned above the head as a means of improving the dose uniformity. Methods and Materials Vetex dosimetry was performed using ion-chamber and TLD. Measurements were 6 MeV electron beam obtained by placing an acrylic beam speller in the beam line. Studies were performed to investigate the effect of electron scattering on vertex dose when a lead reflector $40{\times}40cm$ in area, was positioned above the phantom. Results : The surface dose at the vertex, in the without of the reflector was found to be less than $37.8\%$ of the skin dose. Use of the lead reflector increased this value to $62.2\%$ for the 6 MeV beam. Conclusion : The vertex may be significantly under-dosed using standard techniques for total skin electron beam. Use of an electron reflector improves the dose uniformity at the vertex and may reduce or eliminate the need for supplemental irradiation.

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Feasibility Study of the Radiophotoluminescent Glass Dosimeter for High-energy Electron Beams (유리선량계를 이용한 고에너지 전자선 측정 이용 가능성에 관한 연구)

  • Son, Ki-Hong;Jung, Hai-Jo;Shin, Sang-Hun;Lee, Hyun-Ho;Lee, Sung-Hyun;Kim, Mi-Sook;Ji, Young-Hoon;Kim, Kum-Bae
    • Progress in Medical Physics
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    • v.22 no.1
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    • pp.52-58
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    • 2011
  • Our goal is to assess the suitability of a glass dosimeter on detection of high-energy electron beams for clinical use, especially for radiation therapy. We examined the dosimetric characteristics of glass dosimeters including dose linearity, reproducibility, angular dependence, dose rate dependence, and energy dependence of 5 different electron energy qualities. The GD was irradiated with high-energy electron beams from the medical linear accelerator andgamma rays from a cobalt-60 teletherapy unit. All irradiations were performed in a water phantom. The result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; $R^2$ of 0.999 between 6 and 20 MeV. The reproducibility of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was ${\pm}1.2%$. In terms of the angular dependence to electron beams,GD response differences to the electron beam were within 1.5% for angles ranging from $0^{\circ}$ to $90^{\circ}$ and GD's maximum response differencewas 14% lower at 180o. In the dose rate dependence, measured dose values were normalized to the value obtained from 500 MU/min. The uncertainties of dose rate were measured within ${\pm}1.5%$ except for the value from 100 MU/min. In the evaluation of the energy dependence of the GD at nominal electron energies between 6 and 20 MeV, we obtained lower responses between 1.1% and 4.5% based on cobalt-60 beam. Our results show that GDs have a considerable potentiality for measuring doses delivered by high-energy electron beams.

Preliminary Investigations of the Dosimetric Properties of a Normoxic Polymethacrylic Acid Gel Dosimeter Using a Respiration-Motion Simulator (호흡모의움직임장치를 이용한 정상산소 폴리메타크릴산 겔 선량계의 선량특성)

  • Park, Chae Hee;Cho, Yu Ra;Cho, Kwang Hwan;Park, Ji Ae;Kim, Kyeong Min;Kim, Kum Bae;Jung, Hai Jo;Ji, Young Hoon;Kwon, Soo-Il
    • Progress in Medical Physics
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    • v.23 no.3
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    • pp.138-144
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    • 2012
  • Dose distribution throughout the clinical organ range of motion was analyzed using a respiratory-motion simulator that was equipped with a polymer gel dosimeter and EBT2 film. The normoxic polymer gel dosimeter was synthesized from gelatin, MAA, HQ, THPC and HPLC. The gel dosimeter and EBT2 film were irradiated with Co-60 gamma rays that were moved along the x-axis and y-axis in ${\pm}1.5cm$ steps at five-second intervals. The field size was $5{\times}5cm^2$. The SSD was 80 cm and set to 10 Gy at a depth of 2 cm. The PDD at a depth of 50 mm was 75.2% in the ion chamber, 82.3% in the static state and 86.1% in the dynamic state in the gel dosimeter. The penumbra for the dynamic state target, which was measured using the gel dosimeter, averaged 10.89 mm, this is a 40.5% increase over the penumbra of the static state target of 7.74 mm. In addition, when measuring with gel dosimetry, the value for the penumbra is 36.6% smaller in the static state and 29.4% smaller in the dynamic state compared to measuring with film. The aim of this study was to investigate the dosimetric properties of a normoxic polymethacrylic acid gel dosimeter in static and dynamic states and to evaluate the potentiality as a relative dosimeter for dynamic therapeutic radiation.

Feasibility Study of Vertical Multileaf Collimator for Determination of Irradiation Size (수직형 다엽 콜리메이터의 방사선 조사면 크기 결정을 통한 유용성 연구)

  • Lee, Chang-Yeol;Son, Ki-Hong;Shin, Sang-Hun;Park, Seung-Woo;Lee, Dong-Han;Jung, Hai-Jo;Choi, Mun-Sik;Oh, Won-Young;Kim, Kum-Bae;Yang, Gwang-Mo;Ji, Young-Hoon
    • Progress in Medical Physics
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    • v.22 no.1
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    • pp.3-11
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    • 2011
  • The purpose of this study was to evaluate feasibility of Vertical Multileaf Collimator for determination of irradiation size using Vertical Multileaf Collimator and lead block to determine 4 different irradiation shape in case of Co-60 gamma-ray and 6 MV X-ray. We chose ion chamber, glass dosimeter and EBT chromic film to compare with Vertical Multileaf Collimator results and lead block results. In case of Co-60 gamma-ray and 6 MV X-ray, the central axis point dose normalized at reference field of lead block with ion chamber results for Vertical Multileaf Collimator were estimated higher than lead block about 5.1%, 4.2%. In case of Co-60 gamma-ray, the central axis point dose normalized at reference field of lead block with glass dosimeter results for Vertical Multileaf Collimator were estimated higher than lead block about 2.2%, 7.8%, 7.2%, 4.0% for reference, circle, triangle, cross field, respectively. In case of 6 MV X-ray, the central axis point dose normalized at reference field of lead block with glass dosimeter results for Vertical Multileaf Collimator were estimated higher than lead block about 6.7%, 6.2%, 3.8%, 6.2% for reference, circle, triangle, cross field, respectively. The results of EBT chromic film, Vertical Multileaf Collimator of penumbra size for all irradiation shape was smaller than lead block of those size that 2.0~3.5 mm for Co-60 gamma-ray, 0.5~1.0 mm for 6 MV X-ray. The results from this study, radiation treatment volume that results in shielding block can be minimized. In addition, during radiation treatment for 2, 3-dimensional radiation therapy using a Vertical Multileaf Collimator of this survey can be used to determine variety of irradiation fields.

Comparison of Radiation Dose in the Measurement of MDCT Radiation Dose according to Correction of Temperatures and Pressure, and Calibration of Ionization Chamber (MDCT 선량측정에서 온도와 압력에 따른 보정과 Ionization Chamber의 Calibration 전후 선량의 비교평가)

  • Lee, Chang-Lae;Kim, Hee-Joung;Jeon, Seong-Su;Cho, Hyo-Min;Nam, So-Ra;Jung, Ji-Young;Lee, Young-Jin;Lee, Seung-Jae;Dong, Kyung-Rae
    • Progress in Medical Physics
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    • v.19 no.1
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    • pp.49-55
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    • 2008
  • This study aims to conduct the comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber used for measuring radiation dose in the MDCT, as well as of $CTDI_w$ according to temperature and pressure correction factors in the CT room. A comparative analysis was conducted based on the measured MDCT (GE light speed plus 4 slice, USA) data using head and body CT dosimetric phantom, and Model 2026C electrometer (RADICAL 2026C, USA) calibrated on March 21, 2007. As a result, the $CTDI_w$ value which reflected calibration factors, as well as correction factors of temperature and pressure, was found to be the range of $0.479{\sim}3.162mGy$ in effective radiation dose than the uncorrected values. Also, under the routine abdomen routine CT image acquisition conditions used in reference hospitals, patient effective dose was measured to indicate the difference of the maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the correction of temperature and pressure of the CT room are crucial in measuring and calculating patient effective dose. Thus, to measure patient radiation dose accurately, the detailed information should be made available regarding not only the temperature and pressure of the CT room, but also the humidity and recombination factor, characteristics of X-ray beam quality, exposure conditions, scan region, and so forth.

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Dosimetric Characteristics of a Thermal Neutron Beam Facility for Neutron Capture Therapy at HANARO Reactor (하나로 원자로 BNCT 열중성자 조사장치에 대한 선량특성연구)

  • Lee, Dong-Han;Suh, So-Heigh;Ji, Young-Hoon;Choi, Moon-Sik;Park, Jae-Hong;Kim, Kum-Bae;Yoo, Seung-Yul;Kim, Myong-Seop;Lee, Byung-Chul;Chun, Ki-Jung;Cho, Jae-Won;Kim, Mi-Sook
    • Progress in Medical Physics
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    • v.18 no.2
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    • pp.87-92
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    • 2007
  • A thermal neutron beam facility utilizing a typical tangential beam port for Neutron Capture Therapy was installed at the HANARO, 30 MW multi-purpose research reactor. Mixed beams with different physical characteristics and relative biological effectiveness would be emitted from the BNCT irradiation facility, so a quantitative analysis of each component of the mixed beams should be performed to determine the accurate delivered dose. Thus, various techniques were applied including the use of activation foils, TLDs and ionization chambers. All the dose measurements were perform ed with the water phantom filled with distilled water. The results of the measurement were compared with MCNP4B calculation. The thermal neutron fluxes were $1.02E9n/cm^2{\cdot}s\;and\;6.07E8n/cm^2{\cdot}s$ at 10 and 20 mm depth respectively, and the fast neutron dose rate was insignificant as 0.11 Gy/hr at 10 mm depth in water The gamma-ray dose rate was 5.10 Gy/hr at 20 mm depth in water Good agreement within 5%, has been obtained between the measured dose and the calculated dose using MCNP for neutron and gamma component and discrepancy with 14% for fast neutron flux Considering the difficulty of neutron detection, the current study support the reliability of these results and confirmed the suitability of the thermal neutron beam as a dosimetric data for BNCT clinical trials.

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The Study on Properties and Application of Enhanced Dynamic Wedge Factor (향상된 동적쐐기인자(Enhanced Dynamic Wedge Factor)의 특성 및 적용에 관한 고찰)

  • Kim, Dae-Sup;Ban, Tae-Joon;Yeom, Mi-Suk;Yoo, Soon-Mi;Lee, Woo-Seok;Back, Geum-Mun;Kwon, Kyung-Tae
    • The Journal of Korean Society for Radiation Therapy
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    • v.22 no.1
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    • pp.53-60
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    • 2010
  • Purpose: We try to calculate EDW-factor easily with the formula applies essential data of EDW-factor and evaluate the validity through a measurement. Materials and Methods: We used the given value of GSTT (Golden Segmented Treatment Table) for the calculation of the EDW-factor. As to the experimental device, 0.6 cc farmer-type ion-chamber, an electrometer and water- phantom were used. A measurement was made at the maximum dose depth of the photon beam energy 6 MV and 15 MV under the condition that SSD (Source to Surface Distance) was 100 cm. The angle of the EDW (Enhanced Dynamic Wedge) which we use in an experiment was 60 degree, 30 degree, 20 degree in the Y1-OUT direction. We used Eclipse planning system (Varian, USA) as RTP system and the EDW-factor was calculated about all fields and EDW direction. In order to show the EDW-factor feature, a measurement was made at the selected field that verify the influence of the dependability about X, Y jaw and off-axis field. Results: When we change the Y1 field, it influence on the EDW-Factor and measured value. But the error between measured values and calculated values was less than 1%. The experimental result indicated the tendency that the error of the result of calculation and measured value becomes smaller as the EDW angle become smaller whether the calculation point (measurement point) and iso-center are same or not. The influence of the field size and energy did not show up. We simulated with the same condition using the RTP system. And we found that it makes no difference between the MU which is calculated manually by applying the EDW-Factor obtained from the commercial program and the value which is calculated by using RTP system. Conclusion: We excluded fitting value from well-known EDW-Factor formula and calculated EDW-factor with the formula applies essential data of EDW-factor only. As a result, there are no significant difference between the measured value and calculated value and it showed errors less than 1%. Also, we implemented the commercial program to calculate EDW-Factor conveniently without measure a factor on each field.

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