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  • [Med Phys.] Contact lens-type ocular in vivo dosimeter for radiotherapy.

    [Med Phys.] Contact lens-type ocular in vivo dosimeter for radiotherapy.

    서울대병원 / 김정인, 박종민*

  • 출처
    Med Phys.
  • 등재일
    2020 Feb
  • 저널이슈번호
    47(2):722-735. doi: 10.1002/mp.13932. Epub 2019 Dec 3.
  • 내용

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    Abstract
    PURPOSE:
    This study aimed to (a) develop a contact lens-type ocular in vivo dosimeter (CLOD) that can be worn directly on the eye and (b) assess its dosimetric characteristics and biological stability for radiation therapy.

    METHODS:
    The molder of a soft contact lens was directly used to create the dosimeter, which included a radiation-sensitive component - an active layer similar to a radiochromic film - to measure the delivered dose. A flatbed scanner with a reflection mode was used to measure the change in optical density due to irradiation. The sensitivity, energy, dose rate, and angular dependence were tested, and the uncertainty in determining the dose was calculated using error propagation analysis. Sequential biological stability tests, specifically, cytotoxicity and ocular irritation tests, were conducted to ensure the safe application of the CLOD to patients.

    RESULTS:
    The dosimeter demonstrated high sensitivity in the low dose region, and the sensitivity linearly decreased with the dose. The responses obtained for the 10 and 15 MV photon beams were 1.7% and 1.9% higher compared to the 6 MV photon beam. A strong dose rate dependence was not obtained for the CLOD. Angular dependence was observed from 90° to 180° with a difference in response from 1% to 2%. The total uncertainty in error propagation analysis decreased as a function of the dose in the red channel. For a dose range of 0 to 50 cGy, the total uncertainties for 5, 10, and 50 cGy were 14.2%, 8.9%, and 5%, respectively. Quantitative evaluation using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method presented no cytotoxicity. Further, no corneal opacity, iris reaction, or conjunctival inflammation was observed.

    CONCLUSIONS:
    The CLOD is the first dosimeter that can be worn close to the eye. The results of cytotoxicity and irritation tests indicate that it is a stable medical device. The evaluation of dose characteristics in open field conditions shows that the CLOD can be applied to an in vivo dosimeter in radiotherapy.

     

    그림 . 본 연구에서 개발한 콘택트렌즈 타입 선량계

     


    Author information

    Kim JI1,2,3, Cho JD1,2,4, Son J1,3, Choi CH1,2,3, Wu HG1,2,3,5, Park JM1,2,3,6.
    1
    Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.
    2
    Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.
    3
    Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea.
    4
    Department of Radiation Oncology, College of Medicine, Yonsei University, Seoul, 03722, Republic of Korea.
    5
    Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
    6
    Robotics Research Laboratory for Extreme Environments, Advanced Institute of Convergence Technology, Suwon, 16229, Republic of Korea.

  • 키워드
    contact lens dosimeter; lens dose; ocular dosimeter; radiation therapy
  • 연구소개
    세계 최초로, 수정체 피폭선량을 직접적으로 측정할 수 있는 콘택트렌즈 타입의 선량계(contact lens-type ocular in vivo dosimeter, CLOD)를 개발하고, 이에 대하여 임상시험을 포함한 성능평가를 수행한 논문입니다. 세포독성 및 자극 실험을 통하여 CLOD를 안구에 직접 적용해도 무해함을 확인했습니다. CLOD는 0.05 Gy부터 5 Gy의 영역에서 사용 가능하고, 낮은 energy dependency, dose rate dependency, 및 angular dependency를 보였습니다. 임상시험 결과, 몬테카를로 계산 선량과 CLOD 측정 선량의 차이는 0.3 – 2.8 cGy의 분포를 보였습니다.
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