• Title, Summary, Keyword: 선량평가

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4-Dimensional dose evaluation using deformable image registration in respiratory gated radiotherapy for lung cancer (폐암의 호흡동조방사선치료 시 변형영상정합을 이용한 4차원 선량평가)

  • Um, Ki Cheon;Yoo, Soon Mi;Yoon, In Ha;Back, Geum Mun
    • The Journal of Korean Society for Radiation Therapy
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    • v.30 no.1_2
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    • pp.83-95
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    • 2018
  • Purpose : After planning the Respiratory Gated Radiotherapy for Lung cancer, the movement and volume change of sparing normal structures nearby target are not often considered during dose evaluation. This study carried out 4-D dose evaluation which reflects the movement of normal structures at certain phase of Respiratory Gated Radiotherapy, by using Deformable Image Registration that is well used for Adaptive Radiotherapy. Moreover, the study discussed the need of analysis and established some recommendations, regarding the normal structures's movement and volume change due to Patient's breathing pattern during evaluation of treatment plans. Materials and methods : The subjects were taken from 10 lung cancer patients who received Respiratory Gated Radiotherapy. Using Eclipse(Ver 13.6 Varian, USA), the structures seen in the top phase of CT image was equally set via Propagation or Segmentation Wizard menu, and the structure's movement and volume were analyzed by Center-to Center method. Also, image from each phase and the dose distribution were deformed into top phase CT image, for 4-dimensional dose evaluation, via VELOCITY Program. Also, Using $QUASAR^{TM}$ Phantom(Modus Medical Devices) and $GAFCHROMIC^{TM}$ EBT3 Film(Ashland, USA), verification carried out 4-D dose distribution for 4-D gamma pass rate. Result : The movement of the Inspiration and expiration phase was the most significant in axial direction of right lung, as $0.989{\pm}0.34cm$, and was the least significant in lateral direction of spinal cord, as -0.001 cm. The volume of right lung showed the greatest rate of change as 33.5 %. The maximal and minimal difference in PTV Conformity Index and Homogeneity Index between 3-dimensional dose evaluation and 4-dimensional dose evaluation, was 0.076, 0.021 and 0.011, 0.0 respectfully. The difference of 0.0045~2.76 % was determined in normal structures, using 4-D dose evaluation. 4-D gamma pass rate of every patients passed reference of 95 % gamma pass rate. Conclusion : PTV Conformity Index was more significant in all patients using 4-D dose evaluation, but no significant difference was observed between two dose evaluations for Homogeneity Index. 4-D dose distribution was shown more homogeneous dose compared to 3D dose distribution, by considering the movement from breathing which helps to fill out the PTV margin area. There was difference of 0.004~2.76 % in 4D evaluation of normal structure, and there was significant difference between two evaluation methods in all normal structures, except spinal cord. This study shows that normal structures could be underestimated by 3-D dose evaluation. Therefore, 4-D dose evaluation with Deformable Image Registration will be considered when the dose change is expected in normal structures due to patient's breathing pattern. 4-D dose evaluation with Deformable Image Registration is considered to be a more realistic dose evaluation method by reflecting the movement of normal structures from patient's breathing pattern.

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Development of Algorithm for Evaluation of the Dose with Thermoluminescence Dosimeter (열형광선량계에 의한 선량평가 알고리즘 개발)

  • Song, Myung-Jae;Kim, Hee-Keun;Ha, Chung-Woo;Lee, Tae-Young;Yoon, Suk-Chul
    • Journal of Radiation Protection and Research
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    • v.17 no.2
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    • pp.1-13
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    • 1992
  • The purpose of this study is to develop an algorithm of TLD dose evaluation to meet all requirements stated in ANSI N13. 11-1983. It made the PB-3 TLD of Teledyne Isotopes an object of the development. Personal dosimetry performance testings of the development algorithm have been performed twice through the Atlan-Tech, INC. in accordance with the criteria of testing described in ANSI N13. 11-1983. As ,a result, it is assured that the developed algorithm has complied with all requirements stated in ANSI N13. 11-1983.

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비상 베타선량계의 에너지에 따른 피부 선량평가 알고리즘 개발

  • 조천형;이원근;김종수;윤석철
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.63-68
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    • 1996
  • 열형광 선량계(TLD)를 사용한 피부 선량평가는 베타선의 에너지를 구분함으로 정확히 평가된다. 이는 차폐체에 의한 감쇄효과를 이용하는 방법으로 본 논문에서는 7개의 두께가 다른 알루미늄 차폐체를 사용하였고, TLD로는 미국 Teledyne Isotopes사의 LiF$_{7}$ 선량계를 채택하였다. 비상 베타 선량계의 베타선에 대한 특성실험을 위해 한국 원자력연구소가 확보 하고 있는 PTB 표준선원인 $^{90}$ Sr/ $^{90}$ Y (E$_{max}$=2.27MeV, E$_{avg}$=0.8MeV), $^{204}$Tl(E$_{max}$=0.76MeV, E$_{avg}$=0.26MeV), $^{147}$ Pm (E$_{max}$= 0.225MeV, E$_{avg}$=0.06MeV)에 대한 조사를 하였다. 이런 결과로 비상 베타 선량계의 표준 베타선원에 대한 보정계수와 소자별 반응비를 구할 수 있었고, 이것을 이용하여 미지의 베타선원에 대하여 정확한 선량평가를 하기위한 알고리즘을 개발하였다.

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Design of a TL Personal Dosimeter Identifiable PA Exposure and Development of Its Dose Evaluation Algorithm (후방피폭선량계측이 가능한 TL 개인선량계의 설계 및 선량평가 알고리즘 개발)

  • Kwon, J.W.;Kim, H.K.;Yang, J.S.;Kim, J.L.;Lee, J.K.
    • Journal of Radiation Protection and Research
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    • v.29 no.3
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    • pp.179-186
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    • 2004
  • A single-dosimeter worn on the anterior surface of body of a worker was found to provide significant underestimation of dose to the worker when radiation comes from behind of the human body. Recently, several researchers suggested that this kind of underestimation can be corrected to a certain extent by using an extra dosimeter on the back. But this multiple dosimetry also has the disadvantages like overestimation lowering work efficiency or cost burden. In this study, a single dosimeter introducing asymmetric filters enabled to identify PA exposure was designed by monte-carlo simulation and experiments and its dose evaluation algorithm for AP-PA mixed radiation field was established. This algorithm was applicable to penetrating radiation which had the effective energy more than 100 keV. Besides, the dosimeter and algorithm in this study were possible to be applied to near PA exposure.

Evaluation of the Output Dose of a Linear Accelerator Photon Beams by Using the Ionization Chamber TM31010 Series through TG-51 Protocol to Postal Monitoring Output of RPC for 5 Years (TM31010 계열의 공동이온전리함과 TG-51을 이용한 선형가속기광자선의 5년간 출력선량 평가)

  • Choi, Tae-Jin;Kim, Ok-Bae
    • Progress in Medical Physics
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    • v.22 no.2
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    • pp.92-98
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    • 2011
  • This study is to keep the accuracy and stability of the output dose evaluations for linear accelerator photon beams by using the air ionization chambers (TM31010, 0.125 cc, PTW) through the Task Group 51 protocol. The absorbed dose to water calibration factor $N_{dw}{^{Co-60}}$ was delivered from the air kerma calibration factor $N_k$ which was provided from manufacture through SSDL calibration for determination of output factor. The ionization chamber of TM31010 series was reviewed the calibration factor and other parameters for reduce the uncertainty within ${\pm}2%$ discrepancy and we found the supplied $N_{dw}{^{Co-60}}$ which was derived from Nk has shown a -2.8% uncertainty compare to that of PSDL. The authors provided the program to perform the output dosimetry with TG-51 protocol as it is composed same screen of TG-51 worksheets. The evaluated dose by determination of output factor delivered to postal TLD block for comparison the output dose to that of MDACC (RPC) in postal monitoring program. The results have shown the $1.001{\pm}0.013$ for 6 MV and $0.997{\pm}0.012$ discrepancy for 15 MV X rays for 5 years followed. This study shows the evaluated outputs for linear accelerate photon beams are very close to that of international output monitor with small discrepancy of ${\pm}1.3%$ with high reliability and showing the gradually stability after 2010.

The Performance Test of Teledyne PB-3 Personnel Dosimetry System by Intercomparison Study (국제상호비교검증을 통한 Teledyne PB-3 개인선량계시스템의 성능시험)

  • Lee, Sang-Yoon;Lee, Hyung-Sub;Kim, Jung-Lyul;Yoon, Suk-Chul
    • Journal of Radiation Protection and Research
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    • v.19 no.2
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    • pp.133-145
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    • 1994
  • Recently, the Ministry of Science and Technology issued a Ministerial Ordinance (No 1992-15) about the technical criteria on personnel radiation dosimetry. In today's climate, it is important to demonstrate and document that the processor's systems and services to others meet national standards of quality. The purpose of this study is to verify the performance of the Teledyne PB-3 personnel dosimetry system that is generally used in Korea Atomic Energy Research Institute(KAERI) by intercomparison with Oak Ridge National Laboratory. The KAERI has been participated in this personnel dosimetry intercomparison study(PDIS) program since 1991 and it could be possible to test and calibrate personnel monitoring system. This report presents a summary and analysis of by about 50 dose equivalent measurements reported for PDIS-16 through 18 (1991 -1993) with emphasis on neutron dose equivalent sensitivity, accuracy and precision. Relationships of the PDIS results to occupational neutron monitoring and methods to improve personnel dosimetry performance are also discussed.

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A Study on the Effect of Containment Filtered Venting System to Off-site under Severe Accident (중대사고시 격납건물여과배기계통(CFVS)적용으로 인한 사고영향과 결과 고찰)

  • Jeon, Ju Young;Kwon, Tae-Eun;Lee, Jai-Ki
    • Journal of Radiation Protection and Research
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    • v.40 no.4
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    • pp.244-251
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    • 2015
  • The containment filtered venting system reduces the range of the contamination area around the nuclear power plant by strengthening the integrity of the containment building. In this study, the probabilistic assessment code MACCS2 was used to assess the effect of the CFVS to off-site. The accident source term was selected from a Probabilistic Safety Analysis report of SHINKORI 1&2 Nuclear Power Plant. The three source term categories from 19 STC were chosen to evaluate the effective dose and thyroid dose of residents around the power plant and the dose with CFVS and without CFVS were compared. The dose was calculated according to the distance from the nuclear power plant, so the damage scale based on the distance that exceeds the IAEA criteria for effective dose (100 mSv per 7 days) and thyroid dose (50 mSv per 7 days) were compared. The effective dose reduction rates of the STC-3, STC-4, STC-6 were about 95-99% in the whole range (0~35 km), 96-98% for the thyroid dose. There are similar results between effective dose and thyroid dose. After applying the CFVS, the damage scale that exceeds the effective dose criteria was about 1 km (mean). Especially, the STC-4 damage scale was decreased from 26 km (mean) to 1.2 km (mean) significantly. The damage scale that exceed the thyroid dose criteria was decreased to 2~3 km (mean). The STC-4 damage scale was also decreased significantly as compared to STC-3, STC-6 in terms of effective dose.