• Title/Summary/Keyword: $^{14}C$ 선량평가

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Evaluation after Applicated a Mold to a Paraneoplastic Autoimmune Multiorgan Syndrome Patient with Hypervascular Ulcer in the Oral Cavity during Treatment with Mold Brachytherapy (Paraneoplastic Autoimmune Multiorgan Syndrome으로 인하여 구강 내 국소적으로 발생한 과다혈관성 궤양의 방사선 근접치료 시 자체 제작한 Mold의 유용성 평가)

  • Park, Ju-Kyeong;Lee, Sun-Young;Lim, Seok-Geon;Kwak, Geun-Tak;Lee, Seung-Hun;Kim, Yang-Su;Hwang, Ho-In;Cha, Seok-Yong
    • The Journal of Korean Society for Radiation Therapy
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    • v.21 no.1
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    • pp.25-31
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    • 2009
  • Purpose: Evaluate the mold we have made to improve the reproducibility of the patient position and make homogeneous dose distribution to the treatment volume effectively when treating the patient who has hypervascular ulcer on her tongue caused by paraneoplastic autoimmune multiorgan syndrome by mold brachytherapy. Materials and Methods: The mold is consisted of upper and lower parts. We inserted 2 mm of lead sheet on the gums toward the oral cavity to protect them from unnecessary irradiation during the treatment. We had planned on orthogonal images obtained the patient. 200 cGy was delivered in every fraction with a total dose of 3000 cGy. To evaluate the effect of the lead sheet, we made a measurement with a phantom that has gums and tongue made of tissue with an equivalent material (bolus). Five of TLDs were placed on the interesting points of gums to measure the dose during irradiation with lead sheet and without lead sheet for three times respectively. Results: The result of the measurement without lead sheet are A: 33.9 cGy, B: 30.1 cGy, C: 31.8 cGy, D: 23.3 cGy, E: 24.1 cGy. The results of measurement with lead sheet are A: 20.6 cGy, B: 18.8 cGy, C: 19.6 cGy, D: 14.7 cGy, E: 15.1 cGy. Conclusion: Since we are using the mold made in our department during the treatment of the patient with hypervascular ulcer on tongue, we could deliver a proper dose to the treatment volume. In addition, the mold provided highly accurate and reproducible treatment and reduced the dose to the gums and teeth. Therefore, the possibility of side effects could be decreased significantly.

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Verification of Dose Evaluation of Human Phantom using Geant4 Code (Geant4 코드를 사용한 인체팬텀 선량평가 검증)

  • Jang, Eun-Sung;Choi, Ji-Hoon
    • Journal of the Korean Society of Radiology
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    • v.14 no.5
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    • pp.529-535
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    • 2020
  • Geant4 is compatible with the Windows operating system in C++ language use, enabling interface functions that link DICOM or software. It was simulated to address the basic structure of the simulation using Geant4/Gate code and to specifically verify the density composition and lung cancer process in the human phantom. It was visualized using the Gate Graphic System, i.e. openGL, Ray Tracer: Ray Tracing by Geant4 Tracing, and using Geant4/Gate code, lung cancer is modeled in the human phantom area in 3D, 4D to verify the simulation progress. Therefore, as a large number of new functions are added to the Gate Code, it is easy to implement accurate human structure and moving organs.

Effects of Low-Dose Fractionated Total Body Irradiation on Murine Immune System (마우스에서 전신 저선량 분할 방사선 조사에 의한 면역학적 변화 평가)

  • Kim, Mi-Hyoung;Rhu, Sang-Young;Lim, Dae-Seog;Song, Jie-Young
    • Journal of Radiation Protection and Research
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    • v.39 no.3
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    • pp.134-141
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    • 2014
  • Along with the wide use of radiotherapy in cancer treatment, there is growing interest in beneficial effect of low-dose irradiation (LDI) in cancer therapy. Therefore, we investigate how LDI affects immune responses in mice model. Total body irradiation (TBI) on C57BL/6 mice was given at low-dose rate of $1mGy{\cdot}min^{-1}$ using $^{137}Cs$ source at three times for consecutive three days. Hematological examination, total cell numbers of spleen, populations and characteristics of splenocytes were determined. Total numbers of RBC or platelet in irradiated mice showed no significant changes. WBC counts were decreased in a dose-dependent manner 2 days after TBI, however, these differences are gradually waned until 28 days. Dose-dependent decrease in the number of splenocytes of TBI mice at day 2 was also improved as time progressed. While the level of Foxp3 mRNA was decreased, the frequency of $CD4^+$ T cells and $CD69^+$ cells in spleen was increased at day 2 and 14. Fractionated low-dose TBI on mice exhibited normal body weight with no distinguishable behavior during whole experimental periods. These results suggest that some parameters of immune system could be altered and evaluated by fractionated low-dose TBI and be used to broaden boundary of low dose radiation research.

Evaluation of Residential Radiation Doses from Korean Atomic Power Plants - Effect of Socioenvironmental Inputs (국내 원전주변 주민 방사선 피폭선량 평가 - 입력변수의 영향)

  • 조대철;이갑복
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.4 no.3
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    • pp.223-229
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    • 2003
  • Annual radiation dose of residential individuals near 4 nuclear power plants in Korea was calculated via K-DOSE 60 based on the updated ICRP-60. The critical exposure variables were chosen as radionuclides, exposed organs and intake pathways. From the calculation results, the critical nuclides were found to be $^3$H, $^{133}$ Xe, $^{60}$ Co for Kori plants and $^{14}$ C, $^{41}$ Ar for Wolsung plants. The most critical pathway was 'vegetable intake' for adults and 'milk intake' for infants. However, there was no preference in the effective organs. Sensitivity analyses showed that the chemical composition in a nuclide much more influenced upon the radiation dose than any other input parameters such as food intake, radiation discharge, and transfer/concentration coefficients by more than 10$^2$ factor. The effect of transfer/concentration coefficients on the radiation dose was negligible. All input parameters showed highly estimated correlation with the radiation dose, approxinated to 1.0.

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Evaluation of Absorbed Dose and Skin Dose with MDCT Using Ionization Chamber and TLD (이온 전리함 및 TLD 법을 이용한 Multi-Detector Computed Tomography의 흡수선량 및 체표면 선량 평가)

  • Jeon, Kyung Soo;Oh, Young Kee;Baek, Jong Geun;Kim, Ok Bae;Kim, Jin Hee;Choi, Tae Jin;Jeong, Dong Hyeok;Kim, Jeong Kee
    • Progress in Medical Physics
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    • v.24 no.1
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    • pp.35-40
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    • 2013
  • Recently, the uses of Multi-Detector Computed Tomography (MDCT) for radiation treatment simulation and planning which is used for intensity modulated radiation therapy with high technique are increasing. Because of the increasing uses of MDCT, additional doses are also increasing. The objective of this study is to evaluate the absorbed dose of body and skin undergoing in MDCT scans. In this study, the exposed dose at the surface and the center of the cylindrical water phantom was measured using an pencil ionization chamber, 30 cc ionization chamber and TL Powder. The results of MDCT were 31.84 mGy, 33.58 mGy and 32.73 mGy respectively. The absorbed dose at the surface showed that the TL reading value was 33.92 mGy from MDCT. These results showed that the surface dose was about 3.5% from the MDCT exposure higher than a dose which is located at the center of the phantom. These results mean that the total exposed dose undergoing MDCT 4 times (diagnostic, radiation therapy planning, follow-up et al.), is about 14 cGy, and have to be considered significantly to reduce the exposed dose from CT scan.

Application of Variance Reduction Techniques for the Improvement of Monte Carlo Dose Calculation Efficiency (분산 감소 기법에 의한 몬테칼로 선량 계산 효율 평가)

  • Park, Chang-Hyun;Park, Sung-Yong;Park, Dal
    • Progress in Medical Physics
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    • v.14 no.4
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    • pp.240-248
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    • 2003
  • The Monte Carlo calculation is the most accurate means of predicting radiation dose, but its accuracy is accompanied by an increase in the amount of time required to produce a statistically meaningful dose distribution. In this study, the effects on calculation time by introducing variance reduction techniques and increasing computing power, respectively, in the Monte Carlo dose calculation for a 6 MV photon beam from the Varian 600 C/D were estimated when maintaining accuracy of the Monte Carlo calculation results. The EGSnrc­based BEAMnrc code was used to simulate the beam and the EGSnrc­based DOSXYZnrc code to calculate dose distributions. Variance reduction techniques in the codes were used to describe reduced­physics, and a computer cluster consisting of ten PCs was built to execute parallel computing. As a result, time was more reduced by the use of variance reduction techniques than that by the increase of computing power. Because the use of the Monte Carlo dose calculation in clinical practice is yet limited by reducing the computational time only through improvements in computing power, introduction of reduced­physics into the Monte Carlo calculation is inevitable at this point. Therefore, a more active investigation of existing or new reduced­physics approaches is required.

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Preliminary Post-closure Safety Assessment of Disposal Options for Disused Sealed Radioactive Source (폐밀봉선원 처분방식별 폐쇄후 예비안전성평가)

  • Lee, Seunghee;Kim, Juyoul;Kim, Sukhoon
    • Economic and Environmental Geology
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    • v.49 no.4
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    • pp.301-314
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    • 2016
  • Disused Sealed Radioactive Sources (DSRSs) are stored temporally in the centralized storage facility of Korea Radioactive Waste Agency (KORAD) and planned to be disposed in the low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju city. In this study, preliminary post-closure safety assessment was performed for DSRSs in order to draw up an optimum disposal plan. Two types of disposal options were considered, i.e. engineered vault type disposal and rock cavern type disposal which were planned to be constructed and operated respectively in LILW disposal facility in Gyeongju city. Assessment end-point was individual effective dose of critical group and calculated by using GoldSim code. In normal scenario, the maximum dose was estimated to be approximately $1{\times}10^{-7}mSv/yr$ for both disposal options. It meant that both options had sufficient safety margin when compared with regulatory limit (0.1 mSv/yr). Otherwise, in well scenario, the maximum dose exceeded regulatory limit of 1 mSv/yr in engineered vault type disposal and the exposure dose was mainly contributed by $^{226}Ra$, $^{210}Pb$ (daughter nuclide of $^{226}Ra$) and $^{237}Np$ (daughter nuclide of $^{241}Am$). For rock cavern type disposal, even though the peak dose satisfied regulatory limit, the exposure doses by $^{14}C$ and $^{237}Np$ were relatively high above 10% of regulatory limit. Therefore, it is necessary to exclude $^{14}C$, $^{226}Ra$ and $^{241}Am$ for two type of disposal options and additional management such as long-term storage and development of disposal container for those radionuclides should be performed before permanent disposal for conservative safety and security.

Assessment of the Usefulness of an IMRT Plan Using a Shell-Type Pseudo Target with Patients in Stage III or IV of NSCLC (비소세포폐암 III, IV기 환자에 있어서 Shell-Type Pseudo Target을 이용한 세기 조절 방사선치료계획기법의 유용성 평가)

  • Lee, Sang-Bong;Park, Ki-Ju;Park, Du-Chan;Kim, Man-Wo;Kim, Jun-Gon;Noh, Sung-Hwan
    • The Journal of Korean Society for Radiation Therapy
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    • v.24 no.2
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    • pp.95-106
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    • 2012
  • Purpose: The objective of this study was to investigate the usefulness of an IMRT treatment plan according to whether there was a shell-type pseudo target during radiation therapy for patients in Stage III or IV of non-small cell lung cancer (NSCLC). Materials and Methods: After setting an IMRT (Intensity-Modulated Radiation Therapy, IMRT) plan for when there was a shell-type pseudo target (SPT) and when there was none (WSPT) with 22 patients in Stage III or IV of NSCLC, the investigator analyzed dose-volume histograms (DVHs) and made assessment with dosimetric comparisons such as homogeneity index (HI) inside the tumor target, conformity index (CI) of the tumor target, spinal cord maximum dose, Esophagus $V_{50%}$, mean lung dose (MLD), and $V_{40%}$, $V_{30%}$, $V_{20%}$, $V_{10%}$, $V_{5%}$. Results: The mean CI of WSPT and SPT was $1.22{\pm}0.04$ and $1.16{\pm}0.032$ ($.000^*$), respectively, and the mean HI of WSPT and SPT was $1.06{\pm}0.015$ and $1.07{\pm}0.014$ ($.000^*$), respectively. In SPT, the mean of each CI difference decreased by $-5.16{\pm}2.54%$, while HI increased by average $0.81{\pm}0.47%$. Esophagus $V_{50%}$ recorded $14.54{\pm}12.01%$ (WSPT) and $12.14{\pm}11.09%$ ($.000^*$, SPT) with the mean of SPT differences dropping by $-26.37{\pm}25.05%$. Mean spinal cord maximum dose was $3,898.44{\pm}1,075.0$ cGy (WSPT) and $3,810.8{\pm}1,134.9$ cGy ($.004^*$, SPT) with SPT dropping by average $-3.36{\pm}5.81%$. As for lung $V_{X%}$, the mean of $V_{5%}$ and $V_{10%}$ differences was $-1.62{\pm}2.29%$ ($.006^*$) and $-1.98{\pm}5.02%$ ($.005^*$), respectively with SPT making a decrease. The mean of V20%, V30%, and V40% differences was $-3.51{\pm}3.07%$ ($.000^*$), $-4.84{\pm}6.01%$ ($.000^*$), and $-6.16{\pm}8.46%$ ($.001^*$), respectively, with SPT making a decrease with statistical significance. In MLD assessment, SPT also dropped by average $-2.83{\pm}2.41%$ ($.000^*$). Those results show that SPT allows for mean 169 cGy (Max: 547 cGy, Min: 6.4 cGy) prescription dose. Conclusion: An IMRT treatment plan with SPT during radiation therapy for patients in Stage III or IV of NSCLC will help to reduce the risk of lung toxicity and radiation-induced pneumonia by cutting down radiation doses entering the normal lung, reduce the local control failure rate during radiation therapy due to increasing prescription doses to a certain degree, and increase treatment effects.

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Evaluating efficiency of application the skin flash for left breast IMRT. (왼쪽 유방암 세기변조방사선 치료시 Skin Flash 적용에 대한 유용성 평가)

  • Lim, Kyoung Dal;Seo, Seok Jin;Lee, Je Hee
    • The Journal of Korean Society for Radiation Therapy
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    • v.30 no.1_2
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    • pp.49-63
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    • 2018
  • Purpose : The purpose of this study is investigating the changes of treatment plan and comparing skin dose with or without the skin flash. To investigate optimal applications of the skin flash, the changes of skin dose of each plans by various thicknesses of skin flash were measured and analyzed also. Methods and Material : Anthropomorphic phantom was scanned by CT for this study. The 2 fields hybrid IMRT and the 6 fields static IMRT were generated from the Eclipse (ver. 13.7.16, Varian, USA) RTP system. Additional plans were generated from each IMRT plans by changing skin flash thickness to 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm and 2.5 cm. MU and maximum doses were measured also. The treatment equipment was 6MV of VitalBeam (Varian Medical System, USA). Measuring device was a metal oxide semiconductor field-effect transistor(MOSFET). Measuring points of skin doses are upper (1), middle (2) and lower (3) positions from center of the left breast of the phantom. Other points of skin doses, artificially moved to medial and lateral sides by 0.5 cm, were also measured. Results : The reference value of 2F-hIMRT was 206.7 cGy at 1, 186.7 cGy at 2, and 222 cGy at 3, and reference values of 6F-sIMRT were measured at 192 cGy at 1, 213 cGy at 2, and 215 cGy at 3. In comparison with these reference values, the first measurement point in 2F-hIMRT was 261.3 cGy with a skin flash 2.0 cm and 2.5 cm, and the highest dose difference was 26.1 %diff. and 5.6 %diff, respectively. The third measurement point was 245.3 cGy and 10.5 %diff at the skin flash 2.5 cm. In the 6F-sIMRT, the highest dose difference was observed at 216.3 cGy and 12.7 %diff. when applying the skin flash 2.0 cm for the first measurement point and the dose difference was the largest at the application point of 2.0 cm, not the skin flash 2.5 cm for each measurement point. In cases of medial 0.5 cm shift points of 2F-hIMRT and 6F-sIMRT without skin flash, the measured value was -75.2 %diff. and -70.1 %diff. at 2F, At -14.8, -12.5, and -21.0 %diff. at the 1st, 2nd and 3rd measurement points, respectively. Generally, both treatment plans showed an increase in total MU, maximum dose and %diff as skin flash thickness increased, except for some results. The difference of skin dose using 0.5 cm thickness of skin flash was lowest lesser than 20 % in every conditions. Conclusion : Minimizing the thickness of skin flash by 0.5 cm is considered most ideal because it makes it possible to keep down MUs and lowering maximum doses. In addition, It was found that MUs, maximum doses and differences of skin doses did not increase infinitely as skin flash thickness increase by. If the error margin caused by PTV or other factors is lesser than 1.0 cm, It is considered that there will be many advantages in with the skin flash technique comparing without it.

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Imaging Characteristics of Computed Radiography Systems (CR 시스템의 종류와 I.P 크기에 따른 정량적 영상특성평가)

  • Jung, Ji-Young;Park, Hye-Suk;Cho, Hyo-Min;Lee, Chang-Lae;Nam, So-Ra;Lee, Young-Jin;Kim, Hee-Joung
    • Progress in Medical Physics
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    • v.19 no.1
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    • pp.63-72
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    • 2008
  • With recent advancement of the medical imaging systems and picture archiving and communication system (PACS), installation of digital radiography has been accelerated over past few years. Moreover, Computed Radiography (CR) which was well established for the foundation of digital x-ray imaging systems at low cost was widely used for clinical applications. This study analyzes imaging characteristics for two systems with different pixel sizes through the Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE). In addition, influence of radiation dose to the imaging characteristics was also measured by quantitative assessment. A standard beam quality RQA5 based on an international electro-technical commission (IEC) standard was used to perform the x-ray imaging studies. For the results, the spatial resolution based on MTF at 10% for Agfa CR system with I.P size of $8{\times}10$ inches and $14{\times}17$ inches was measured as 3.9 cycles/mm and 2.8 cycles/mm, respectively. The spatial resolution based on MTF at 10% for Fuji CR system with I.P size of $8{\times}10$ inches and $14{\times}17$ inches was measured as 3.4 cycles/mm and 3.2 cycles/mm, respectively. There was difference in the spatial resolution for $14{\times}17$ inches, although radiation dose does not effect to the MTF. The NPS of the Agfa CR system shows similar results for different pixel size between $100{\mu}m$ for $8{\times}10$ inch I.P and $150{\mu}m$ for $14{\times}17$ inch I.P. For both systems, the results show better NPS for increased radiation dose due to increasing number of photons. DQE of the Agfa CR system for $8{\times}10$ inch I.P and $14{\times}17$ inch I.P resulted in 11% and 8.8% at 1.5 cycles/mm, respectively. Both systems show that the higher level of radiation dose would lead to the worse DQE efficiency. Measuring DQE for multiple factors of imaging characteristics plays very important role in determining efficiency of equipment and reducing radiation dose for the patients. In conclusion, the results of this study could be used as a baseline to optimize imaging systems and their imaging characteristics by measuring MTF, NPS, and DQE for different level of radiation dose.

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