• Title/Summary/Keyword: Ir-192 source measurement

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High Dose Rate Ir-192 Source Calibration Method with Newly Designed Calibration Jig (고선량 Ir-192선원 교정기의 제작 및 특성)

  • Yi, Byong-Yong;Choi, Eun-Kyung;Chang, Hye-Sook
    • Radiation Oncology Journal
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    • v.7 no.2
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    • pp.299-303
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    • 1989
  • Authors have developed highly reproducible calibration method for the Micro-Selectron HDR Ir-192 system (Nucletron, Motherland). The new jig has a 10cm radius circular hole in the $30cm{\times}30cm{\times}0.2cm$ acrylic plate, and 5F flexible bronchial tubes are attached around the hole. The source moves along the circle in the tubes and the ionization chamber is placed verticaly at the center of the circular hole (center of the jig). Dose distribution near the center was derived theoretically, and measured with the film dosimetry system. Theoretical calculation and measurement show the error margin below $0.1\%$ for 1mm or 2mm position deviation. We have measured at 12 and 24 points of circle with 1, 6, 11 and 21 second dwell time of source in order to calculate the activity of the source. Measurements have been repeated daily for 50 days. The accuracy and the reproducibility are below $1\%$ error margin. The half life of the source from our measurement is estimated $73.4\pm0.4$ days.

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Study on the Compatibility for an Ir-192 Source Manufactured by Korea Atomic Energy Research Institute (KAERI) in GammaMed Brachytherapy Machine (한국원자력연구소에서 개발한 Ir-192 선원의 감마메드 치료기 호환성 연구)

  • Jeong, Dong-Hyeok;Lee, Kang-Kyoo;Kim, Soo-Kon;Moon, Sun-Rock
    • Progress in Medical Physics
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    • v.21 no.1
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    • pp.78-85
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    • 2010
  • The compatibility with GammaMed-12i brachytherapy machine for an Ir-192 encapsulated source (IRRS20, KAERI, Korea) manufactured by Korea atomic energy research institute (KAERI) has been investigated. As a mechanical testing of compatibility, precise measurement of step movement with channels, measurement of curvature of radius for wire, and emergency return testing were performed. Periodic measurements of air kerma strength for 45 days were carried out to evaluate decay characteristics of Ir-192 radioisotope and comparison of dose distributions in phantom between KAERI and old sources previously used were performed by film dosimetry. KAERI source has a good compatibility with GammaMed12i machine as a result of mechanical testing. There are in good agreement with calculated values in activity characteristics and there were small differences in dose distributions around the source in comparison between KAERI and old source.

Determination of Exposure Dose Rate and Isotropic Distributions of Substitute High Dose Rate Ir-192 Source for Co-60 Brachytherapy Source (원격강내조사용 Co-60 선원의 대체용 Ir-192 선원의 조사선량결정 및 선량 등방성조사)

  • 최태진;원철호;김옥배;김시운;김금배;조운갑;한현수;박경배
    • Progress in Medical Physics
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    • v.9 no.1
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    • pp.55-64
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    • 1998
  • In recent, the demand of development of the high dose rate brachytherapy source increased for substitute for Co-60 source by iridium source, since the supplying Co-60 source is very depressed and the high dose rate brachytherapy sources are entirely imported from the abroad. This study investigated the exposure rates and isotropic dose distributions for the Ir-192 source produced from $\^$191/Ir(n,r)$\^$192/Ir by nuclear reactor in Korea Atomic Energy Research Institute. The activity of source was obtained an 1.012 Ci (the initial activity without encapsulation was 2,87Ci) by measurement with encapsuled stainless steel. The exposure rate of provided Ir-192 source was determined on 6.36 ${\pm}$ 0.147 Rm$^2$/h-GBq (2.350 ${\pm}$ 0.054 Rcm$^2$/mCi-hr) within ${\pm}$ 2.2% discrepancy with IC-10 ion chamber (0.14 cc) which was mounted on the acrylic jig to 5, 10 and 20 cm from the center of source. The calculated doses with 22 most significant spectrum lines were corrected with intrinsic efficiency of the germanium detector were compared to measured exposure dose rates within ${\pm}$3.8 % discrepancy. The authors confirmed the high dose rate Ir-192 source could be replaced the long decayed Co-60 source via investigation of the isotropic dose distributions in lateral, source axis and diagonal direction of source center are very closed to within 3% uncertainties. Especially, this exposure rate constant and isotropic dose distribution will be fundamental to build the high dose rate source and develop the computed therapy planning system.

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The Activity Check of Brachytherapy Isotope (근접치료동위원소의 Activity Check)

  • Kim, Gun-Oh;Lee, Byung-Koo;Kwon, Young-Ho
    • The Journal of Korean Society for Radiation Therapy
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    • v.16 no.1
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    • pp.21-27
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    • 2004
  • An isotope Ir-192, which is used in brachytherapy depends on import in whole quantities. There are a few ways for its activity. measurement using Welltype chamber or the way to rely on authentic decay table of manufacturer. In-air dosimetry using Farmer Chamber, etc. In this paper, let me introduce the way using Farmer chamber which is easier and simple. With the Farmer chamber and source calibration jig, take a measurement the activity of an isotope Ir-192 and compare the value with the value from decay table of manufacturer and check the activity of source. The result of measurement, compared the value from decay table, by ${\pm}2.1\%$. (which belongs to recommendable value for AAPM ${\pm}5\%$ as difference of error range) It is possible to use on clinical medicine. With the increase in use of brachytherapy, the increase of import is essential. And an accurate activity check of source is compulsory. For the activity check of source, it was possible to use Farmer chamber and source calibration jig without additional purchase of Well type chamber.

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A Study on Calibration Procedures for Ir-192 High Dose Rate Brachytherapy Sources (고선량률(HDR) 근접치료의 동위원소 Ir-192에 대한 측정방법에 관한 고찰)

  • Baek, Tae-Seong;Lee, Seung-Wook;Na, Soo-Kyong
    • The Journal of Korean Society for Radiation Therapy
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    • v.19 no.1
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    • pp.19-26
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    • 2007
  • Purpose: To compare of the accuracy among various measurement procedures of HDR Brachytherapy, and to evaluate the clinical suitability and usefulness of alternative PMMA (polymethylmethacrylateplastics: $C_5H_8O_2$) plate phantom without any additional cost due to the purchase of measuring apparatus. Materials and Methods: We made a comparative study on three types of measuring systems: well type chamber, source calibration jig, and PMMA plate phantom. Farmer type chamber was used for source calibration jig method and PMMA plate phantom method. Measurement was done 5 times each in comparison with the measurement values from manufacturer. Measurement results from experiment were compared with that from the manufacturer which is offered with the source whenever a source is substituted by a new one and evaluate the accuracy of source activity. Results: As a consequence of Ir-192 source measurement using well type chamber, source calibration jig and PMMA plate phantom, RMS (Root Mean Square) values for the relative error are 0.6%, 1.57%, 2.1%, respectively, compared with the data from manufacturer. And the mean errors with standard deviation are given $-0.2{\pm}0.5%$, $0.97{\pm}1.23%$, $-0.89{\pm}1.87%$ respectively. Conclusion: From the results shown by the three types of measurement system (well type chamber, source calibration jig, and PMMA plate phantom), the measurement with well type chamber produced the best accuracy. It turns out that we can also use the alternative system of PMMA plate phantom clinically without purchasing any additional particular apparatus since the system does not exceed the recommendation of AAPM (American Association of Physicists in Medicine), which requires the error range of within ${\pm}5%$.

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Measurement of Ir-192 Source Activity for High Dose Rate Brachytherapy (고 선량률 근접치료시 사용되는 Ir-192 선원의 방사능 평가)

  • 최동락;허승재;안용찬;임도훈;김대용;우홍균
    • Progress in Medical Physics
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    • v.8 no.1
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    • pp.25-29
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    • 1997
  • Ir-192 source activity for high dose rate brachytherapy is measured using Farmertype ionization chamber. The source-to-chamber distance is 10 cm and the measured charge unit is converted to activity unit. The measured values are compared to the values provided from vendor. Because of time dependency of Ir-192 source activity, the activities are regularly checked and compared to calculated values. As the accuracy of Ir-192 source activity is depend on the mechanical measurement setup, we estimated the precision of remote controlled source dwell position using home-made device and film scanner. The difference between measured and predicted dwell position is within 1 mm. As a result, the errors of source activity are 0.7${\pm}$1.5 % for measured and vendor-provided values and 0.l${\pm}$1.2% for measured and time-dependent calculated vlaues. In conclusion, our measured activity has been comparable to the values provided from vendor and our brachytherapy unit has been very accurate until now. Regular quality control of brachytherapy is essential for successful treatment which depends on the accuracy of source position and activity.

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Characteristics of Tissue Dose of High Dose Rate Ir-192 Source Substitution for Co-60 Brachytherapy Source (코발트-60 선원 대체용 고선량률 Ir-192 선원의 조직선량특성)

  • 최태진;이호준;김옥배
    • Progress in Medical Physics
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    • v.9 no.4
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    • pp.259-266
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    • 1998
  • To achieve the 2D dose distribution around the designed high dose rate Ir-192 source substitution for Co-60 brachytherapy source, we determined the exposure rate constant and tissue attenuation factors as a large depth as a 20 cm from source center. The exposure rate constant is used for apparent activity in designed source with self-absorption and encapsulation steel wall. The tissue dose delivered from the 4401 segments of 2.5 mm in a diameter and 2.5 mm height of disk-type source layer. In the experiments, the tissue attenuation factors include the tissue attenuation and multiple scattering in a medium surrounding the source. The fitted the polynomial regression with 4th order for the tissue attenuation factors are very closed to the experimental measurement data within ${\pm}$1% discrepancy. The Meisberger's constant showed the large uncertainty in large distance from source. The exposure rate constant 4.69 Rcm$^2$/mCi-hr was currently used for determination of apparent activity of source and air kerma strength was obtained 0.973 for tissue absorbed dose from the energy spectrum of Ir-192 source. In our experiments with designed high dose rate brachytherapy source, the apparent activity of Ir-192 source was delivered from the 54.6 % of actual physical source activity through the self-absorption and encapsulation wall attenuations. This paper provides the 2-dimensional dose tabulation from unit apparent activity in a water medium for dose planning includes the multiple scattering, source anisotropy effect and geometric factors.

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Development of Real-Time Thickness Measuring System for Insulated Pipeline Using Gamma-ray (감마선을 이용한 단열배관의 실시간 두께측정시스템 개발)

  • Jang, Ji-Hoon;Kim, Byung-Joo;Kim, Gi-Dong;Cho, Kyung-Shik
    • Journal of the Korean Society for Nondestructive Testing
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    • v.22 no.5
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    • pp.500-507
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    • 2002
  • By this study, on-line real-time radiometric system was developed using a 64 channels linear array of solid state detectors to measure wall thickness of insulated piping system. This system uses an Ir-192 as a gamma ray source and detector is composed of BGO scintillator and photodiode. Ir-192 gamma ray source and linear detector array mounted on a computer controlled robotic crawler. The Ir-192 gamma ray source is located on one side of the piping components and the detector array on the other side. The individual detectors of the detector array measure the intensity of the gamma rays after passing through the walls and the insulation of the piping component under measurement. The output of the detector array is amplified by amplifier and transmitted to the computer through cable. This system collects and analyses the data from the detector array in real-time as the crawler travels over the piping system. The maximum measurable length of pipe is 120cm/min. in the case of 1mm scanning interval.

Comparison of Non-Destructive Testing Images using $^{192}Ir$ and $^{75}Se$ with Computed Radiography System (Computed Radiography 시스템에 $^{192}Ir$$^{75}Se$ 동위원소를 적용하여 촬영한 비파괴검사 영상 비교)

  • Kang, Sang-Mook;Chol, Chang-Il;Lee, Seung-Kyu;Park, Sang-Ki;Kim, Yong-Kyun
    • Journal of Radiation Protection and Research
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    • v.35 no.1
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    • pp.26-33
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    • 2010
  • A computed Radiography (CR) system by use of reusable Image Plate (IP) offers a convenient and reliable way to replace a conventional film-screen system for NDT (non-destructive testing) field. The quality of a radiography to detect a defect of welded objects depends on the procedure embracing several factors such as measurement conditions, image plate type/class, radiation energy, radiation type, and source to image plate distance. Also, the ability of images to detect a flaw reduces with increasing object thickness. In the study, the properties of gamma ray source were summarized for NDT field and inspection images of CR image system manufactured by FUJI were acquired using $^{75}Se$ and $^{192}Ir$ with welded objects. We analyzed the gray scale of hole defect image by using XCAP image processing program and calculated the image contrast and SNR in definition. Also the sesitivities of image quality indicator(IQI) were calculated for hot and cooling tube image of $^{75}Se$ and $^{192}Ir$.

Development of Real Time On-Line Thickness Measuring System for Insulated Pipeline (단열배관의 온라인 두께측정시스템 개발)

  • Jang, Ji-Hun;Kim, Byeong-Ju;Jo, Gyeong-Sik;Kim, Gi-Dong
    • 연구논문집
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    • s.32
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    • pp.65-76
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    • 2002
  • The intensity of x-ray or gamma-ray is attenuated according to density and thickness of the transmitted medium. In this study, by using this principle, on-line real-time radiometric system was developed using a 128 channels linear array of solid state detectors to measure wall thickness of insulated piping system. This system uses a Ir-192 as a gamma ray source and detector is composed of BGO scintillator and photodiode. Ir-192 gamma ray source and linear detector array mounted on a computer controlled robotic crawler. The Ir-192 gamma ray source is located on one side of the piping components and the detector array on the other side. The individual detectors of the detector array measure the intensity of the gamma rays after passing through the walls and the insulation of the piping component under measurement. The output of the detector array is amplified by amplifier and transmitted to the computer. This system collects and analyses the data from the detector array in real-time. The maximum measurable length of pipe is 120cm/mm. in the case of 1mm scanning interval.

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