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Effective dose assessment with optically stimulated luminescence dosimetry and Monte Carlo calculation in CBCT

Other Titles
 광자극발광선량계(OSLD)측정법과 몬테카를로 산출법(MC)에 의한 콘빔시티의 유효선량 평가 
Authors
 박창희 
Degree
박사
Issue Date
2018
Description
치의학전문대학원
Abstract
Objective: The aim of this study was to evaluate the effective dose of three different cone beam computed tomography (CBCT) units with optically stimulated luminescence dosimeters (OSLD). Also, this dosimetric measurement method was compared with Monte Carlo (MC) simulation in Alphard 3030 CBCT unit. Through the measurement process and obtained value, more practical and efficient method in acquiring the effective dose of a CBCT would be suggested. Materials and Methods: Twenty-two optically stimulated luminescence dosimeters (OSLD) were calibrated and equipped in human anthropomorphic phantom of head and neck. The phantom with dosimetry was exposed respectively with C, P and I modes of Alphard 3030 (Asahi Roentgen Ind., Co. Ltd, Kyoto, Japan); Large Jaw and Jaw modes of RAYSCAN α+ (Ray Co. Ltd, Hwaseong-si, Korea); Facial and Dual Jaw modes of CS9300 (Carestream Dental LLC, Atlanta, Georgia). Dose recorded in dosimetry was obtained and organ dose as well as effective dose were obtained in each examination mode of 3 CBCT units. The organ and effective dose were also obtained with MC simulation on three examination modes of Alphard 3030 CBCT unit. For MC simulation, PCXMC software (STUK, Helsinki, Finland) was used and dose-area-product (DAP) value was measured with DAP meter. Results: The effective dose was the highest in C mode, Alphard 3030 and the lowest in Dual jaw mode, CS9300. When comparing the 10 x10 cm FOV mode of all 3 CBCT units, the effective dose was higher in order of Alphard 3030 (258.8 µSv), RAYSCAN α+ (213.8 µSv), and CS9300 (90.7 µSv). The organ dose was the highest in salivary gland and the lowest in bone marrow in the same FOV mode of 3 CBCT units. When compared the result of OSLD in Alphard 3030 with MC simulation, percent difference of the effective dose was 9.8~23.4%. Overall organ dose distribution was consistent in all different examination modes of Alphard 3030 CBCT unit. Conclusion: The effective dose showed tendency of increasing as FOV increased regardless of the CBCT model. In addition, the effective dose varies depending on several other factors such as exposure conditions and geometry of the CBCT, thus the effective dose of various equipment should be examined in the future. Also, MC simulation is expected to be convenient assessment method because it was similar to the OSLD measured value according to the examination modes. 목적: 광자극발광선량계(OSLD)를 이용하여 세 종류의 콘빔시티에서 유효선량을 측정하고, Alphard 3030 콘빔시티에서 OSLD 측정값과 몬테카를로(MC) 시뮬레이션 산출값을 비교하는 것이다. 이를 통해 콘빔시티 유효선량을 획득하기 위한 보다 실용적이고 효율적인 방법을 제안하고자 한다. 재료 및 방법: 초기 보정을 거친 22개의 OSLD를 성인 두경부를 재현한 ATOM (CIRS, Norfolk, VA) 팬텀의 정해진 위치에 각각 삽입하였다. 준비된 팬텀을 세 종류의 콘빔시티를 이용하여 제조사가 제시한 노출조건으로 촬영하였다. Alphard 3030 콘빔시티(Asahi Roentgen Ind., Co. Ltd, Kyoto, Japan)에서 C, P, I 3가지 모드, RAYSCAN α+ 콘빔시티(Ray Co. Ltd, Hwaseong-si, Korea)에서 Large jaw, jaw 2가지 모드, CS9300 콘빔시티(Carestream Dental LLC, Atlanta, Georgia)에서 Facial, Dual jaw 2가지 모드로 각각 촬영하였다. 모드 별로 OSLD 측정값을 얻고, 장기 흡수선량과 유효선량을 산출하였다. 또한 Alphard 3030의 3가지 모드에서는 선량면적곱측정계 DAP meter (VacuDAPTM; VacuTec Meßtechnik GmbH, Dresden, Germany)로 노출선량을 측정하였다. 이 값을 통해 PCXMC 소프트웨어(STUK, Helsinki, Finland)를 사용하여 몬테카를로 산출법으로 장기 흡수선량과 유효선량을 획득하였다. OSLD와 MC 두 방법 간의 유효선량 차이를 % 오차로 비교하였다. 결과: OSLD로 측정한 유효선량은 Alphard 3030 C 모드에서 가장 높았고 (599.0 µSv), CS 9300 Dual jaw 모드에서 가장 낮았다 (90.7 µSv). 조사야 크기가 10×10 cm으로 동일한 모드 간의 유효선량을 비교하면 Alphard 3030 (258.8 µSv), RAYSCAN α+ (213.8 µSv), CS9300 (90.7 µSv) 순서대로 높게 나타났다. 장기별 흡수선량은 콘빔시티의 종류와 상관없이 타액선에서 가장 높았고, 골수에서 가장 낮았다. Alphard 3030 콘빔시티의 OSLD 측정값과 MC 산출값을 비교해보면, 유효선량의 두 방법 간 퍼센트 오차는 9.8~23.4 %를 보였다. 두 방법 간의 장기별 흡수선량의 전반적인 분포는 Alphard 3030 콘빔시티의 검사 모드와 상관없이 비슷한 양상을 보였다. 결론: MC 산출값은 검사 모드에 따른 OSLD 측정값과 유사한 수준의 결과를 보였다. 따라서 MC 산출법은 임상에서 사용할 수 있는 편리한 방사선량측정 방법으로 기대된다. 중심단어: 몬테카를로방법, 선량측정법, 콘빔시티, 광자극발광선량계
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Appears in Collections:
2. College of Dentistry (치과대학) > Others (기타) > 3. Dissertation
URI
https://ir.ymlib.yonsei.ac.kr/handle/22282913/166472
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