• Title/Summary/Keyword: 중성자선

Search Result 30, Processing Time 0.025 seconds

Measurement of Growth Delay and the Oxygen Enhancement Ratio of Fast Neutron Beam Using Mouse Model System (마우스모델을 이용한 고속중성자선의 성장지연 및 산소증강비의 측정)

  • Eom, Keun-Yong;Park, Hye-Jin;Kwon, Eun-Kyung;Ye, Sung-Joon;Lee, Dong-Han;Wu, Hong-Gyun
    • Journal of Radiation Protection and Research
    • /
    • v.32 no.4
    • /
    • pp.178-183
    • /
    • 2007
  • Neutrons are high LET (linear energy transfer) radiation and cause more damage to the target cells than x-rays or gamma rays. The damage from neutrons is generally considered fatal to a cell and neutrons have a greater tendency to cause cell death through direct interaction on DNA. We performed experiments to measure growth delay ratio and oxygen enhancement ratio (OER) in mouse model system. We inoculated EMT-6 cells to the right hind leg of BALB-c mouse and X-rays and neutron beams were given when the average volume of tumors reached $200-300mm^3$. We irradiated 0, 11, 15.4 Gy of X-ray and 0, 5, 7 Gy of fast neutron beam at normoxic and hypoxic condition. The volume of tumors was measured 3 times per week. In x-ray experiment, growth delay ratio was 1.34 with 11 Gy and 1.33 with 15.4 Gy in normoxic condition compared to in hypoxic condition, respectively. In neutron experiment, growth delay ratio was 0.94 with 5 Gy and 0.98 with 7 Gy, respectively. The OER of neutron beam was 0.97. The neutron beam was more effective than X-ray in the control of hypoxic tumors.

Different Expressions of HIF-$1\alpha$, Bcl-2 and Baxin DU145 Prostate Cancer Cells Transplanted in Nude Mouse between X-Ray and Neutron Irradiation (누드마우스에 주입된 DU-145 전립샘암에서 엑스선과 중성자선에 의한 HIF-$1\alpha$, Bcl-2, Bax 발현의 차이)

  • Kong, Moon-Kyoo;Kang, Jin-Oh;Kim, Sang-Ki;Shin, Dong-Oh;Park, Seo-Hyun;Kim, Chang-Ju;Chang, Hyun-Kyung
    • Radiation Oncology Journal
    • /
    • v.27 no.4
    • /
    • pp.218-227
    • /
    • 2009
  • Purpose: To investigate the radiobiologic effects of neutron and X-ray irradiation on DU-145 prostate carcinoma cells by identifying the differences of HIF-$1\alpha$ expression and apoptosis. Materials and Methods: Nude mice were injected with the human prostate cancer cell line, DU-145, and then irradiated with 2 Gy and 10 Gy X-rays, or 0.6 Gy and 3.3 Gy neutrons, respectively. The mice were sacrificed at 24 hours and 120 hours after irradiation. The expression levels of HIF-$1\alpha$, Bcl-2 and Bax were compared with immunohistochemical staining and western blotting. The apoptotic indexes were compared with the Terminal deoxynucleotidyl biotin-dUTP nick and labeling (TUNEL) assay. Results: At day 1, HIF-$1\alpha$ and Bcl-2 expression decreased, while Bax expression and the number of TUNEL positive cells increased in neutron irradiated groups for the control and X-ray irradiated groups. The Bcl-2/Bax ratio was significantly lower in the neutron irradiated groups regardless of dose (p=0.001). The same pattern of the differences in the expressions of the HIF-$1\alpha$, Bcl-2, Bax, Bcl-2/Bax ratio, and apoptotic indexes were indentified at day 5. HIF-$1\alpha$ expression was related with Bcl-2 (p=0.031), Bax (p=0.037) expressions and the apoptotic indexes (p=0.016) at day 5. Conclusion: Neutron irradiation showed a decrease in HIF-$1\alpha$, Bcl-2 expression, and Bcl-2/Bax ratio, but increased Bax expression regardless of dose. This study suggests that the differences radiobiological responses between photon and neutron irradiation may be related to different HIF-$1\alpha$ expression and subsequent apoptotic protein expressions.

Compositional Qualification of Radiation Protection in Neutron Radiotherapy Room with KCCH Cyclotron (원자력병원(原子力病院) 싸이클로트론 중성자선(中性子線) 치료실(治療室)의 방사선(放射線) 방어(防禦)에 관한 총합적(總合的) 평가(評價))

  • Yoo, Seong-Yul;Cho, Chul-Koo;Koh, Kyoung-Hwan
    • Journal of Radiation Protection and Research
    • /
    • v.14 no.2
    • /
    • pp.45-50
    • /
    • 1989
  • Radiation exposure of the personnel in the neutron therapy facility of KCCH cyclotron neutron system is discussed. In neutron therapy room, medical personnel is exposed to photons of the remanent induced radioactivity from the isocentric gantry in which targets and collimators are mounted. The radiation level of the neutron therapy room of KCCH cyclotron was acceptable and it decreased immediately after beam off. Personal exposure measured by individual monitor was far less than permissible level.

  • PDF

Evaluation of Biological Characteristics of Neutron Beam Generated from MC50 Cyclotron (MC50 싸이클로트론에서 생성되는 중성자선의 생물학적 특성의 평가)

  • Eom, Keun-Yong;Park, Hye-Jin;Huh, Soon-Nyung;Ye, Sung-Joon;Lee, Dong-Han;Park, Suk-Won;Wu, Hong-Gyun
    • Radiation Oncology Journal
    • /
    • v.24 no.4
    • /
    • pp.280-284
    • /
    • 2006
  • $\underline{Purpose}$: To evaluate biological characteristics of neutron beam generated by MC50 cyclotron located in the Korea Institute of Radiological and Medical Sciences (KIRAMS). $\underline{Materials\;and\;Methods}$: The neutron beams generated with 15 mm Beryllium target hit by 35 MeV proton beam was used and dosimetry data was measured before in-vitro study. We irradiated 0, 1, 2, 3, 4 and 5 Gy of neutron beam to EMT-6 cell line and surviving fraction (SF) was measured. The SF curve was also examined at the same dose when applying lead shielding to avoid gamma ray component. In the X-ray experiment, SF curve was obtained after irradiation of 0, 2, 5, 10, and 15 Gy. $\underline{Results}$: The neutron beams have 84% of neutron and 16% of gamma component at the depth of 2 cm with the field size of $26{\times}26\;cm^2$, beam current $20\;{\mu}A$, and dose rate of 9.25 cGy/min. The SF curve from X-ray, when fitted to linear-quadratic (LQ) model, had 0.611 as ${\alpha}/{\beta}$ ratio (${\alpha}=0.0204,\;{\beta}=0.0334,\;R^2=0.999$, respectively). The SF curve from neutron beam had shoulders at low dose area and fitted well to LQ model with the value of $R^2$ exceeding 0.99 in all experiments. The mean value of alpha and beta were -0.315 (range, $-0.254{\sim}-0.360$) and 0.247 ($0.220{\sim}0.262$), respectively. The addition of lead shielding resulted in no straightening of SF curve and shoulders in low dose area still existed. The RBE of neutron beam was in range of $2.07{\sim}2.19$ with SF=0.1 and $2.21{\sim}2.35$ with SF=0.01, respectively. $\underline{Conclusion}$: The neutron beam from MC50 cyclotron has significant amount of gamma component and this may have contributed to form the shoulder of survival curve. The RBE of neutron beam generated by MC50 was about 2.2.

Frequency of Micronuclei in Lymphocytes Following Gamma and Fast-neutron Irradiations (방사선 조사량에 따른 인체 정상 림파구의 미세핵 발생빈도)

  • Kim Sung-Ho;Cho Chul-Koo;Kim Tae-Hwan;Chung In-Yong;Yoo Seong-Yul;Koh Kyoung-Hwan;Yun Hyong-Geun
    • Radiation Oncology Journal
    • /
    • v.11 no.1
    • /
    • pp.35-42
    • /
    • 1993
  • The dose response of the number of micronuclei in cytokinesis-blocked (CB) lymphocytes after in vitro irradiation with $\gamma$-rays and neutrons in the 5 dose ranges was studied for a heterogeneous population of 4 donors. One thousand binucleated cells were systematically scored for micronuclei. Measurements performed after irradiation showed a dose-dependent increase in micronuclei (MN) frequency in each of the donors studied. The dose-response curves were analyzed by a linear-quadratic model, frequencies per 1000 CB cells were ($0.31{\pm}0.049$)D+($0.0022{\pm}0.0002)D^2+(13.19{\pm}1.854) (r^2=1.000,\;X^2=0.7074,\;p=0.95$) following $\gamma$ irradiation, and ($0.99{\pm}0.528$)\;D+(0.0093{\pm}0.0047)\;D^2+(13.31{\pm}7.309)\;(r^2=0.996,\;X^2=7.6834,\;p=0.11) following neutrons irradiation (D is irradiation dose in cGy). The relative biological effectiveness (RBE) of neutrons compared with $\gamma$-rays was estimated by best fitting linear-quadratic model. In the micronuclei frequency between 0.05 and 0.8 per cell, the RBE of neutrons was $2.37{\pm}0.17$. Since the MN assay is simple and rapid, it may be a good tool for evaluating the $\gamma$-ray and neutron response.

  • PDF

The Relative Biological Effectiveness of KCCH-Cyclotron neutron (원자력병원(原子力病院) 싸이클로트론 속중성자선(速中性子線)의 방사선생물학적효과비(RBE)에 관(關)한 연구(硏究))

  • Yoo, Seong-Yul;Koh, Kyoung-Hwan;Cho, Chul-Koo;Kim, Sung-Ho
    • Journal of Radiation Protection and Research
    • /
    • v.12 no.2
    • /
    • pp.1-8
    • /
    • 1987
  • The relative biological effectiveness has been measured for the biological characterization of $p^+(50.5\;MeV)$ Be neutron of KCCH-Cyclotron prior to clinical application. Measured RBE of mouse jejunal crypt cell in single whole body irradiation was 2.8. This RBE value is changed differently in different biologic systems such as mouse jejunal crypt cells, intestine and bone marrow in different irradiation method, so that in fractionated irradiation RBE is variable to the different fraction size and total dose, and also variable to the number of fractions.

  • PDF

The Change of Asphalt Content by The Position of Neutron Source (중성자선원의 위치에 따른 아스팔트 함량의 변화)

  • Kim, Ki-Joon
    • 전자공학회논문지 IE
    • /
    • v.45 no.2
    • /
    • pp.6-12
    • /
    • 2008
  • In this study, because of the importance of asphalt content, the target is to develop a asphalt content detector that the influence of the jurisdiction and usage of radioisotopes are limited of 100[${\mu}Ci$] or less. For development of a asphalt content detector, it is divided into three parts that is affected the change of asphalt content due to the position of neutron source. First part is to decrease the distance between asphalt mixture and neutron source, second is to install the reflector, and last is to change the history number. It performed to analysis by computer simulation and satisfactory results of error range can use to design data for development of a asphalt content detector.