• Title/Summary/Keyword: Medical radiation

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The first KREDOS-EPR intercomparison exercise using alanine pellet dosimeter in South Korea

  • Park, Byeong Ryong;Kim, Jae Seok;Yoo, Jaeryong;Ha, Wi-Ho;Jang, Seongjae;Kang, Yeong-Rok;Kim, HyoJin;Jang, Han-Ki;Han, Ki-Tek;Min, Jeho;Choi, Hoon;Kim, Jeongin;Lee, Jungil;Kim, Hyoungtaek;Kim, Jang-Lyul
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2379-2386
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    • 2020
  • This paper presents the results of the first intercomparison exercise performed by the Korea retrospective dosimetry (KREDOS) working group using electron paramagnetic resonance (EPR) spectroscopy. The intercomparison employed the alanine dosimeter, which is commonly used as the standard dosimeter in EPR methods. Four laboratories participated in the dose assessment of blind samples, and one laboratory carried out irradiation of blind samples. Two types of alanine dosimeters (Bruker and Magnettech) with different geometries were used. Both dosimeters were blindly irradiated at three dose levels (0.60, 2.70, and 8.00 Gy) and four samples per dose were distributed to the participating laboratories. Assessments of blind doses by the laboratories were performed using their own measurement protocols. One laboratory did not participate in the measurements of Magnettech alanine dosimeter samples. Intercomparison results were analyzed by calculating the relative bias, En value, and z-score. The results reported by participating laboratories were overall satisfactory for doses of 2.70 and 8.00 Gy but were considerably overestimated with a relative bias range of 10-95% for 0.60 Gy, which is lower than the minimum detectable dose (MDD) of the alanine dosimeter. After the first intercomparison, participating laboratories are working to improve their alanine-EPR dosimetry systems through continuous meetings and are preparing a second intercomparison exercise for other materials.

Four-Dimensional Computed Tomography for Gated Radiotherapy: Retrospective Image Sorting and Evaluation

  • Lim, Sang-Wook;Park, Sung-Ho;Back, Geum-Mun;Ahn, Seung-Do;Shin, Seong-Soo;Lee, Sang-Wook;Kim, Jong-Hoon;Choi, Eun-Kyuong;Kwon, Soo-Il
    • Proceedings of the Korean Society of Medical Physics Conference
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    • 2005.04a
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    • pp.71-74
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    • 2005
  • To introduce the four-dimensional computed tomography (4DCT, Light Speed RT, General Electric, USA) scanner newly installed in our department and evaluate its feasibility for gated radiotherapy. Respiratory signal measured by real-time position management (RPM$^{\circledR}$, Varian Medical, USA) was recorded in synchronization with the 4DCT scanner. 4DCT data were acquired in axial cine mode and sorted retrospective image based on respiratory phase. PTVs delineated from helical CT and 4DCT images were compared. The PTV delineated from conventional helical CT images was 2 cc larger than that from 4DCT images. Dose in PTV of the plan from retrospective CT was 99.3% (minimum=72.0%, maximum=106.5%) and that of helical CT plan was 95.2% (minimum=24.1%, maximum=106.4%) of prescribed dose. Comparing with DVHs of both plan, the coverage for 4CDT plan was 3.7% improved. It is expected that 4DCT could improve tumor control and reduce radiation toxicity for liver cancer.

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Radiological Operating Technicians's Protective Behaviors on Radio-medical Measures in Hospitals (의료기관 방사선종사자들의 방사선안전관리에 대한 행위)

  • Han, Eun-Ok;Moon, In-Ok
    • The Journal of Korean Society for School & Community Health Education
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    • v.8 no.1
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    • pp.69-77
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    • 2007
  • Background & Objectives: International radiation protection committee recognized the importance of radiation protection from medical practices because the exposure to the radiation in medical practice is higher than any other exposure. The factors on knowledge, attitude and practice of radiation safety of the medical workers engaged in radiation were analyzed in order to improve radiation safety technology. Method: Questionnaires were used for 1200 radiation workers in medical institution from July 23 through September 4 and collected for analysis. Results: Different level of safety measures were practiced by age, marital status, career, and medical facility. The difference was statistically significant. Higher levels of safety measures were practiced in the age group of 50s and married persons. The workers who have more than 20 years experience have higher level of safety measures. The workers of health centers have higher level of safety measures to compare with other workers. The factors which give more concerns on safety practice were self efficacy, practice and knowledge in order. Conclusion: Safety conscious operators should get additional education program to maintain higher level of safety. The operators who do not have much safety concern should be intensive training program for self efficacy and safety.

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Identification of Specific Gene Modules in Mouse Lung Tissue Exposed to Cigarette Smoke

  • Xing, Yong-Hua;Zhang, Jun-Ling;Lu, Lu;Li, De-Guan;Wang, Yue-Ying;Huang, Song;Li, Cheng-Cheng;Zhang, Zhu-Bo;Li, Jian-Guo;Xu, Guo-Shun;Meng, Ai-Min
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.10
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    • pp.4251-4256
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    • 2015
  • Background: Exposure to cigarette may affect human health and increase risk of a wide range of diseases including pulmonary diseases, such as chronic obstructive pulmonary disease (COPD), asthma, lung fibrosis and lung cancer. However, the molecular mechanisms of pathogenesis induced by cigarettes still remain obscure even with extensive studies. With systemic view, we attempted to identify the specific gene modules that might relate to injury caused by cigarette smoke and identify hub genes for potential therapeutic targets or biomarkers from specific gene modules. Materials and Methods: The dataset GSE18344 was downloaded from the Gene Expression Omnibus (GEO) and divided into mouse cigarette smoke exposure and control groups. Subsequently, weighted gene co-expression network analysis (WGCNA) was used to construct a gene co-expression network for each group and detected specific gene modules of cigarette smoke exposure by comparison. Results: A total of ten specific gene modules were identified only in the cigarette smoke exposure group but not in the control group. Seven hub genes were identified as well, including Fip1l1, Anp32a, Acsl4, Evl, Sdc1, Arap3 and Cd52. Conclusions: Specific gene modules may provide better understanding of molecular mechanisms, and hub genes are potential candidates of therapeutic targets that may possible improve development of novel treatment approaches.

Adjuvant Radiotherapy after Breast Conserving Treatment for Breast Cancer:A Dosimetric Comparison between Volumetric Modulated Arc Therapy and Intensity Modulated Radiotherapy

  • Liu, Zhe-Ming;Ge, Xiao-Lin;Chen, Jia-Yan;Wang, Pei-Pei;Zhang, Chi;Yang, Xi;Zhu, Hong-Cheng;Liu, Jia;Qin, Qin;Xu, Li-Ping;Lu, Jing;Zhan, Liang-Liang;Cheng, Hong-Yan;Sun, Xin-Chen
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.8
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    • pp.3257-3265
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    • 2015
  • Background: Radiotherapy is an important treatment of choice for breast cancer patients after breast-conserving surgery, and we compare the feasibility of using dual arc volumetric modulated arc therapy (VMAT2), single arc volumetric modulated arc therapy (VMAT1) and Multi-beam Intensity Modulated Radiotherapy (M-IMRT) on patients after breast-conserving surgery. Materials and Methods: Thirty patients with breast cancer (half right-sided and half left-sided) treated by conservative lumpectomy and requiring whole breast radiotherapy with tumor bed boost were planned with three different radiotherapy techniques: 1) VMAT1; 2) VMAT2; 3) M-IMRT. The distributions for the planning target volume (PTV) and organs at risk (OARs) were compared. Dosimetries for all the techniques were compared. Results: All three techniques satisfied the dose constraint well. VMAT2 showed no obvious difference in the homogeneity index (HI) and conformity index (CI) of the PTV with respect to M-IMRT and VMAT1. VMAT2 clearly improved the treatment efficiency and can also decrease the mean dose and V5Gy of the contralateral lung. The mean dose and maximum dose of the spinal cord and contralateral breast were lower for VMAT2 than the other two techniques. The very low dose distribution (V1Gy) of the contralateral breast also showed great reduction in VMAT2 compared with the other two techniques. For the ipsilateral lung of right-sided breast cancer, the mean dose was decreased significantly in VMAT2 compared with VMAT1 and M-IMRT. The V20Gy and V30Gy of the ipsilateral lung of the left-sided breast cancer for VMAT2 showed obvious reduction compared with the other two techniques. The heart statistics of VMAT2 also decreased considerably compared to VMAT1 and M-IMRT. Conclusions: Compared to the other two techniques, the dual arc volumetric modulated arc therapy technique reduced radiation dose exposure to the organs at risk and maintained a reasonable target dose distribution.

Fingernail electron paramagnetic resonance dosimetry protocol for localized hand exposure accident

  • Jae Seok Kim;Byeong Ryong Park;Minsu Cho;Won Il Jang;Yong Kyun Kim
    • Nuclear Engineering and Technology
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    • v.55 no.1
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    • pp.270-277
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    • 2023
  • Exposure to ionizing radiation induces free radicals in human nails. These free radicals generate a radiation-induced signal (RIS) in electron paramagnetic resonance (EPR) spectroscopy. Compared with the RIS of tooth enamel samples, that in human nails is more affected by moisture and heat, but has the advantages of being sensitive to radiation and easy to collect. The fingernail as a biological sample is applicable in retrospective dosimetry in cases of localized hand exposure accidents. In this study, the dosimetric characteristics of fingernails were analyzed in fingernail clippings collected from Korean donors. The dose response, fading of radiation-induced and mechanically induced signals, treatment method for evaluation of background signal, minimum detectable dose, and minimum detectable mass were investigated to propose a fingernail-EPR dosimetry protocol. In addition, to validate the practicality of the protocol, blind and field experiments were performed in the laboratory and a non-destructive testing facility. The relative biases in the dose assessment result of the blind and field experiments were 8.43% and 21.68% on average between the reference and reconstructed doses. The results of this study suggest that fingernail-EPR dosimetry can be a useful method for the application of retrospective dosimetry in cases of radiological accidents.

Involvement of Cdc25c in Cell Cycle Alteration of a Radioresistant Lung Cancer Cell Line Established with Fractionated Ionizing Radiation

  • Li, Jie;Yang, Chun-Xu;Mei, Zi-Jie;Chen, Jing;Zhang, Shi-Min;Sun, Shao-Xing;Zhou, Fu-Xiang;Zhou, Yun-Feng;Xie, Cong-Hua
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.10
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    • pp.5725-5730
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    • 2013
  • Cancer patients often suffer from local tumor recurrence after radiation therapy. Cell cycling, an intricate sequence of events which guarantees high genomic fidelity, has been suggested to affect DNA damage responses and eventual radioresistant characteristics of cancer cells. Here, we established a radioresistant lung cancer cell line, A549R, by exposing the parental A549 cells to repeated ${\gamma}$-ray irradiation with a total dose of 60 Gy. The radiosensitivity of A549 and A549R was confirmed using colony formation assays. We then focused on examination of the cell cycle distribution between A549 and A549R and found that the proportion of cells in the radioresistant S phase increased, whereas that in the radiosensitive G1 phase decreased. When A549 and A549R cells were exposed to 4 Gy irradiation the total differences in cell cycle redistribution suggested that G2-M cell cycle arrest plays a predominant role in mediating radioresistance. In order to further explore the possible mechanisms behind the cell cycle related radioresistance, we examined the expression of Cdc25 proteins which orchestrate cell cycle transitions. The results showed that expression of Cdc25c increased accompanied by the decrease of Cdc25a and we proposed that the quantity of Cdc25c, rather than activated Cdc25c or Cdc25a, determines the radioresistance of cells.

Dosimetric comparison of volumetric modulated arc therapy with robotic stereotactic radiation therapy in hepatocellular carcinoma

  • Paik, Eun Kyung;Kim, Mi-Sook;Choi, Chul Won;Jang, Won Il;Lee, Sung Hyun;Choi, Sang Hyoun;Kim, Kum Bae;Lee, Dong Han
    • Radiation Oncology Journal
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    • v.33 no.3
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    • pp.233-241
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    • 2015
  • Purpose: To compare volumetric modulated arc therapy of RapidArc with robotic stereotactic body radiation therapy (SBRT) of CyberKnife in the planning and delivery of SBRT for hepatocellular carcinoma (HCC) treatment by analyzing dosimetric parameters. Materials and Methods: Two radiation treatment plans were generated for 29 HCC patients, one using Eclipse for the RapidArc plan and the other using Multiplan for the CyberKnife plan. The prescription dose was 60 Gy in 3 fractions. The dosimetric parameters of planning target volume (PTV) coverage and normal tissue sparing in the RapidArc and the CyberKnife plans were analyzed. Results: The conformity index was $1.05{\pm}0.02$ for the CyberKnife plan, and $1.13{\pm}0.10$ for the RapidArc plan. The homogeneity index was $1.23{\pm}0.01$ for the CyberKnife plan, and $1.10{\pm}0.03$ for the RapidArc plan. For the normal liver, there were significant differences between the two plans in the low-dose regions of $V_1$ and $V_3$. The normalized volumes of $V_{60}$ for the normal liver in the RapidArc plan were drastically increased when the mean dose of the PTVs in RapidArc plan is equivalent to the mean dose of the PTVs in the CyberKnife plan. Conclusion: CyberKnife plans show greater dose conformity, especially in small-sized tumors, while RapidArc plans show good dosimetric distribution of low dose sparing in the normal liver and body.