• Title/Summary/Keyword: Radiation Dosimeter

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Experimental study on build up characteristic of glass dosimeter of preheat and Non-preheat in low energy according to delay time (저에너지X선 영역에서 유리선량계의 preheat과 Non-preheat과의 시간에 따른 build up 특성에 관한 연구)

  • Son, Jin-Hyun;Min, Jung-Whan;Kim, Ki-Won;Son, Soon-Yong;Lim, Hyun-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.7
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    • pp.3412-3418
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    • 2013
  • The Purpose of this study was to evaluate by comparing the dose change and build up characteristic according to delay time in 30 days of glass dosimeter processed preheat and non preheat when measuring accumulation dose of radiation by using glass dosimeter over the long haul. For obtaining low dose with 0.1 mGy, 1 mGy and 5 mGy, we employed diagnostic generator AccuRay-650R. We compared the build up characteristic over the long haul by exposuring radiation to 30 glass dosimeters sorted into 10 glass dosimeters per tube voltage and current. In Non preheat glass dosimeter, initial measured dose was inferior to exposed dose but as time goes on, was close to exposed dose steadily. In 72 hour after experiment end, non preheat glass dosimeters were not indicated the difference from preheat glass dosimeters and statistical analysis were meaningful (p>0.05). Initial measured dose for low glass dosimeter processed preheat was close to exposed dose and stable. After 15 days dose was gradually increased. Previous study characteristics of glass dosimeter were with respect to characteristic of glass dosimeter in high dose of high energy area. However, in this study, we make a judgment to measure the dose of glass dosimeter without preheat processing when measuring the accumulation dose of low dose in conclusion.

The Study of Energy Compensation Filter Thickness for Each Energy Area of Low Energy X-ray Beam Optimization on Active Electronic Personal Dosimeter (능동형 전자식 개인피폭선량계의 저에너지 X선 영역별 최적화를 위한 에너지보상 필터 두께에 대한 연구)

  • Kim, Jung-Su;Park, Youn-Hyun;Chae, Hyun-Sic
    • Journal of the Korean Society of Radiology
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    • v.16 no.5
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    • pp.519-526
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    • 2022
  • Electronic personal dosimeter (EPD) provide real time monitoring and a direct indication of the accumulated dose or dose rate in terms of personal dose. Most EPD do not perform well in low energy photon radiation fields present in medical radiation environments. It has poor responsibility and large error rate for low energy photon radiation of medical radiation environments. This study evaluated to optimal additional filtration for EPD using silicon PIN photodiode detector form 40 to 120 kVp range in medical radiation environments. From 40 to 80 kVp energy range, Al 0.2 mm and Sn 1.0 mm overlapped filtration showed good responsibility to dose rate and from 80 kVp to 120 kVp energy range, Al 0.2 mm and Sn 1.6 mm overlapped filtration showed good responsibility to dose rate.

A Study on the Presentation of Entrance Surface Dose Model using Semiconductor Dosimeter, General Dosimeter, Glass Dosimeter: Focusing on Comparative Analysis of Effective Dose and Disease Risk through PCXMC 2.0 based on Monte Carlo Simulation (반도체 선량계, 일반 선량계, 유리 선량계를 이용한 입사표면선량 모델 제시에 관한 연구: 몬테카를로 시뮬레이션 기반의 PCXMC 2.0을 통한 유효선량과 발병 위험도의 비교분석을 중심으로)

  • Hwang, Jun-Ho;Lee, Kyung-Bae
    • Journal of the Korean Society of Radiology
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    • v.12 no.2
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    • pp.149-157
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    • 2018
  • One of the purposes of radiation protection is to minimize stochastic effects. PCXMC 2.0 is a Monte Carlo Simulation based program and makes it possible to predict effective dose and the probability of cancer development through entrance surface dose. Therefore, it is especially important to measure entrance surface dose through dosimeter. The purpose of this study is to measure entrance surface dose through semiconductor dosimeter, general dosimeter, glass dosimeter, and to compare and analyze the effective dose and probability of disease of critical organs. As an experimental method, the entrance surface dose of skull, chest, abdomen was measured per dosimeter and the effective dose and the probability of cancer development of critical organs per area was evaluated by PCXMC 2.0. As a result, the entrance surface dose per area was different in the order of a general dosimeter, a semiconductor dosimeter, and a glass dosimeter even under the same condition. Base on this analysis, the effective dose and probability of developing cancer of critical organs were also different in the order of a general dosimeter, a semiconductor dosimeter, and a glass dosimeter. In conclusion, it was found that the effective dose and the risk of diseases differ according to the dosimeter used, even under the same conditions, and through this study it was found that it is important to present an accurate entrance surface dose model according to each dosimeter.

Design of Multipurpose Phantom for External Audit on Radiotherapy

  • Lim, Sangwook
    • Progress in Medical Physics
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    • v.32 no.4
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    • pp.122-129
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    • 2021
  • Purpose: This study aimed to design a multipurpose dose verification phantom for external audits to secure safe and optimal radiation therapy. Methods: In this study, we used International Atomic Energy Agency (IAEA) LiF powder thermoluminescence dosimeter (TLD), which is generally used in the therapeutic radiation dose assurance project. The newly designed multipurpose phantom (MPP) consists of a container filled with water, a TLD holder, and two water-pressing covers. The size of the phantom was designed to be sufficient (30×30×30 cm3). The water container was filled with water and pressed with the cover for normal incidence to be fixed. The surface of the MPP was devised to maintain the same distance from the source at all times, even in the case of oblique incidence regardless of the water level. The MPP was irradiated with 6, 10, and 15 MV photon beams from Varian Linear Accelerator and measured by a 1.25 cm3 ionization chamber to get the correction factors. Monte Carlo (MC) simulation was also used to compare the measurements. Results: The result obtained by MC had a relatively high uncertainty of 1% at the dosimetry point, but it showed a correction factor value of 1.3% at the 5 cm point. The energy dependence was large at 6 MV and small at 15 MV. Various dosimetric parameters for external audits can be performed within an hour. Conclusions: The results allow an objective comparison of the quality assurance (QA) of individual hospitals. Therefore, this can be employed for external audits or QA systems in radiation therapy institutions.

Fabrication and Evaluation of Mercury(II) Iodide Unit Cell Dosimeter to Confirm the Feasibility of Digital Quality Assurance in Intracavitary Radiotherapy (방사선 근접치료의 디지털 정도관리 가능성 확인을 위한 HgI2 Unit Cell 선량계의 제작 및 평가)

  • Jung, Jae-Hoon;Park, Sung-Kwang
    • Journal of the Korean Society of Radiology
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    • v.16 no.3
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    • pp.257-263
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    • 2022
  • In intracavitary radiotherapy, it is essential to verify the correct location of radiation source among quality control items because an incorrect location will irradiate an unnecessary dose to normal tissues. As a basic study of digital line dosimeters, this study fabricated a unit cell dosimeter based on polycrystalline mercury (II) iodide (HgI2) and compared its performance with a diode. The study result showed that for reproducibility, the relative standard deviation (RSD) was 1.21%, satisfying the RSD evaluation criterion of within 1.5%. Considering linearity, the coefficient of determination R2 showed an excellent result of 0.9997. Regarding the evaluation of distance dependence, it showed a similar trend in general with a difference of 0.035 cm for intensity 50% when compared with the inverse square value. This study suggests the applicability of a digital dosimeter for brachytherapy quality control by evaluating the performance of the HgI2 dosimeter. This study on dosimeter for candidate photoconductor materials can be used as basic data in all areas using radiation.

A study of Curved Dosimeter for Flattening Filter Free Beam Quality Assurance Evaluation using Curved Dosimeter in Radiotherapy (Flattening Filter Free Beam의 정도관리를 위한 곡면선량계 가능성 연구)

  • Han, Moojae;Shin, Yohan;Jung, Jaehoon;Heo, Seunguk;Kim, Kyotae;Heo, Yeji;Cho, Heunglae;Park, Sungkwang
    • Journal of the Korean Society of Radiology
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    • v.13 no.1
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    • pp.119-124
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    • 2019
  • Radiation therapy using flattening filter free beam can prevent beam attenuation caused by flattening filter and can improve treatment efficiency. However, accurate dose control is not established for nonuniform iso dose distributions. In this study, curved dosimeter based on photoconductive material $HgI_2$ was fabricated and its reproducibility and linearity were evaluated at 6 MV photon energy to verify its performance. In order to show the usefulness of the curved measurement, the signals measured on the flat substrate and the curved substrate were compared in the flattening filter free beam using the acrylic filter. As a result, the reproducibility of the unit cell dosimeter was evaluated as SE 0.613%, and the linearity was evaluated as R-sq 0.9999. The usability evaluation of the array curve dosimeter demonstrated its usefulness by indicating a curvature error rate of 11.073%p and a reduced error rate.

Performance Evaluation of Lead (II) Oxide Dosimeter for Digital Quality Assurance in Brachytherapy (방사선 근접치료의 디지털 정도관리를 위한 Lead (II) Oxide 선량계 성능 평가)

  • Han, Moo-Jae;Yang, Seung-Woo;Park, Sung-Kwang
    • Journal of the Korean Society of Radiology
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    • v.15 no.4
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    • pp.429-435
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    • 2021
  • In intracavitary radiotherapy, incorrect location of the source can cause excessive dose to normal tissue, so it is essential to evaluate the location accuracy of the source. In this study, basic research was performed on digital line dosimeter based on lead (II) oxide (PbO) to improve analog verification method. Therefore, a polycrystalline PbO unit cell dosimeter was manufactured and the measurement performance for Ir-192 sources was evaluated. As a result, the reproducibility satisfies the evaluation criteria of 1.5% with a relative standard deviation of 0.85%. Linearity showed excellent results with a linear coefficient of R2 of 0.9998. In the case of distance dependence evaluation, the power function R2 showed 0.9855 for PbO and 0.9974 for diode, and the overall average difference was 1.66% for PbO and 2.18% for diode. This study presents the basic detection performance of the polycrystalline PbO dosimeter for the Ir-192 source and can provide basic data in the field of radiation measurement.

Study on the Dose Characteristics of the PTW-LinaCheck Dosimeter and Its Application to Daily Output Measurement (PTW-LinaCheck 측정기의 선량 특성과 일일 출력측정 응용에 관한 연구)

  • Jeong, Dong-Hyeok;Lee, Kang-Kyoo;Moon, Un-Chul;Kim, Hyun-Jin;Kim, Young-Seok;Moon, Sun-Rock
    • Progress in Medical Physics
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    • v.19 no.1
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    • pp.56-62
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    • 2008
  • In this study, we have investigated the dose characteristics of PTW-LinaCheck designed to detect output of medical LINAC and discussed clinical use of the detector. The reproducibility, linearity, and dose rate dependency of the dosimeter were measured for photons of 6 and 15MV and the electrons of 4, 6, 9, 12, and 16MeV. To know the error ranges of the measured data in daily output measurement, the response variations due to geometrical setup errors were measured. As a result of measurement, the error range from the geometrical setup and the reproducibility was less than ${\pm}0.6%$ for given beam qualities in daily output measurement, where the errors from the linearity and the dose rate dependency were negligible. Finally, we concluded that the LinaCheck dosimeter has a good characteristics in terms of dose and setup convenience in daily output measurement. In addition we have shown an examples of clinical use of this dosimeter for measuring daily output more than 60 days.

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Energy Dependancy of the Polyethylene Terephthalate Film for Radiation Detector (방사선 검출기용 PET 박막의 에너지 의존성)

  • Back, Geum-Mun;Kim, Keon-Chung;Kim, Wang-Gon;Hong, Jin-Woong;Yi, Byong-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.71-74
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    • 2002
  • Currently small and accurate dosimeters are on the rise. In this study, the feasibility and energy dependency of the electret dosimeter that made of PET (polyethylene terephtalate) were observed by irradiating 4, 6, 15 MV photon beams from the clinical linear accelerator to develop a dosimeter for the clinical field. $10{\times}10cm$ field size of the photon beams were irradiated to the electret dosimeter where the 2.5 cm depth in the polystylene phantom from 100 cm SSD, while 300 DCV was applied to the electret dosimeter. The result showed that the absorbed dose was proportional to the charge linearly, and the volume of a dosimeter could be reduced and the signals were high enough. According to this study, it was found that the polymer electret detector could be produced as a large quantity with a small cost and showed the feasibility of a realtime measurement.

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Simulation and design of individual neutron dosimeter and optimization of energy response using an array of semiconductor sensors

  • Noushinmehr, R.;Moussavi zarandi, A.;Hassanzadeh, M.;Payervand, F.
    • Nuclear Engineering and Technology
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    • v.51 no.1
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    • pp.293-302
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    • 2019
  • Many researches have been done to develop and improve the performance of personal (individual) dosimeter response to cover a wide of neutron energy range (from thermal to fast). Depending on the individual category of the dosimeter, the semiconductor sensor has been used to simplify and lightweight. In this plan, it's very important to have a fairly accurate counting of doses rate in different energies. With a general design and single-sensor simulations, all optimal thicknesses have been extracted. The performance of the simulation scheme has been compared with the commercial and laboratory samples in the world. Due to the deviation of all dosimeters with a flat energy response, in this paper, has been used an idea of one semi-conductor sensor to have the flat energy-response in the entire neutron energy range. Finally, by analyzing of the sensors data as arrays for the first time, we have reached a nearly flat and acceptable energy-response. Also a comparison has been made between Lucite-PMMA ($H_5C_5O_2$) and polyethylene-PE ($CH_2$) as a radiator and $B_4C$ has been studied as absorbent. Moreover, in this paper, the effect of gamma dose in the dosimeter has been investigated and shown around the standard has not been exceeded.