DOI QR코드

DOI QR Code

방사선사고시 피폭선량평가를 위한 휴대전화 부품의 전자상자성공명(EPR) 특성에 대한 예비 연구

Preliminary Study on Electron Paramagnetic Resonance(EPR) Signal Properties of Mobile Phone Components for Dose Estimation in Radiation Accident

  • 투고 : 2015.04.21
  • 심사 : 2015.09.17
  • 발행 : 2015.12.31

초록

본 연구에서는 전자상자성공명(electron paramagnetic resonance, EPR) 장치를 사용한 휴대전화 부품들의 EPR 특성 측정을 통해 방사선사고시 회구적 선량평가용 선량계로써 활용가능성에 대하여 확인하였다. 화면표시 방식이 다른 두 스마트폰에서 12개의 시료를 선정하여 실험에 사용하였고, 시료의 방사선조사에는 $^{137}Cs$ 감마선 그리고 EPR 측정은 실온에서 Bruker사의 ELEXSYS E500 X-Band EPR spectrometer를 사용하여 수행하였다. 먼저 각 시료에 대하여 비조사시료와 조사시료의 EPR 스펙트럼을 측정하여 방사선에 의한 라디칼 생성 여부를 확인하였고, 그 후 선량반응곡선과 시간에 따른 시그널 크기 변화를 측정하였다. 측정결과 유심 플라스틱과 IC 칩을 제외한 모든 시료에서 방사선에 의한 EPR 시그널 증가를 확인할 수 있었다. 시료 중에서 덮개유리, 카메라렌즈, 도광판, 확산시트는 결정계수 $R^2=0.93$이상의 좋은 선형상관관계를 보였다. 특히 도광판은 선량에 따른 시그널 증가량이 가장 크고 백그라운드 시그널이 없기 때문에 선량평가에 이상적인 특성을 가지고 있었지만, 72 시간 이내에 시그널이 약 50% 감소하는 약점이 있었다. 확산시트 또한 도광판과 유사한 페이딩 특성을 나타내었고, 덮개유리와 카메라렌즈는 단기간 동안에는 시그널이 안정적으로 보존되었다. 휴대전화 부품을 이용한 EPR 선량평가를 실제 대규모 방사선 사고에서 신속하게 적용하기 위해서는 더 많은 휴대전화 기종의 같은 부품에 대한 시그널 차이, 페이딩, 시료 전처리 방법 등에 대한 추가연구가 진행될 필요가 있다. 그러나 현재 결과를 바탕으로 소규모 방사선사고시 피폭환자가 소지하고 있던 휴대전화와 동일한 제품을 구입하여 비교하는 방법 또는 추가조사법을 이용한 선량평가는 가능할 것으로 판단된다.

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by $^{137}Cs$ gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity ($R^2$ > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.

키워드

참고문헌

  1. Committee European de Normalisation(CEN). Detection of irradiated food containing bone, Method by ESR spectroscopy. European Committee for Standardization. EN 1786. 1996.
  2. Committee European de Normalisation(CEN). Detection of irradiated food containing crystalline sugar, Method by ESR spectroscopy. European Committee for Standardization. EN 13708. 2001.
  3. Committee European de Normalisation(CEN). Detection of irradiated food containing cellulose, Method by ESR spectroscopy. European Committee for Standardization. EN 1787. 2000.
  4. International Organization for Standardization (ISO)/American Society for Testing and Materials (ASTM). Practice for use of an alanine-EPR dosimetry system. ISO/ASTM. ISO/ASTM 51607. 2013
  5. International Atomic Energy Agency(IAEA). Use of electron paramagnetic resonance dosimetry with tooth enamel for retrospective dose assessment. IAEA. IAEA-TECDOC-1331. 2002
  6. Swartz HM, Flood AB, Williams BB, Dong R, Swarts SG, He X, Grinberg O, Sidabras J, Demidenko E, Gui J, Gladstone DJ, Jarvis LA, Kmiec MM, Kobayashy K, Lesniewski PN, Marsh SDP, Matthews TP, Nicolalde RJ, Pennington PM, Raynolds T, Salikhov I, Wilcox DE, Zaki BI. Electron Paramagnetic Resonance dosimetry for a large-scale radiation incident. Health Phys. 2012; 103(3):255-267. https://doi.org/10.1097/HP.0b013e3182588d92
  7. Kinoshita A, Calcina CSG, Sakamoto-Hojo ET, Camparato ML, Picon C, Baffa O. Evaluation of a high dose to a finger from a $^{60}Co$, Health Phys. 2003;84(4):477-482. https://doi.org/10.1097/00004032-200304000-00007
  8. Wu K, Sun CP, Shi YM. Dosimetric properties of watch glass: a potential practical ESR dosemeter for nuclear accidents. Radiat Prot Dosim. 1995;5:223-225
  9. Wu K, Guo L, Cong JB, Sun CP, Hu JM, Zhou ZS, Wang S, Zhang Y, Zhang X, Shi YM Researches and applications of ESR dosimetry for radiation accident dose. Radiat Prot Dosim. 1998; 77(1/2):65-67. https://doi.org/10.1093/oxfordjournals.rpd.a032296
  10. Longo A, Basile S, Brai M, Marrale M, Tranchina L. ESR response of watch glasses to proton beams. Nucl Instrum Meth A. 2010;B 268:2712- 2718.
  11. Trompier F, Della Monaca S, Fattibene P, Clairand I. EPR dosimetry of glass substrate of mobile phone LCDs. Radiat Meas. 2011;46:827-831.
  12. Fattibene P, Trompier F, Wieser A, Brai M, Ciesielski B, Angelis CD, Monaca SD, Garcia T, Gustafsson H, Hole EO, Juniewicz M, Krefft K, Longo A, Leveque P, Lund E, Marrale M, Michalec B, Mierzwinska G, Rao JL, Romanyukha AA, Tuner H. EPR dosimetry intercomparison using smart phone touch screen glass. Radiat Environ Biophs. 2014;53:311-320.
  13. Teixeira MI, Ferraz GM, Caldas LVE. EPR dosimetry using commercial glasses for high gamma doses. Appl Radiat Isotopes. 2005;62:365-370. https://doi.org/10.1016/j.apradiso.2004.08.012