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  • [Med Phys.] Development of a deformable lung phantom with 3D-printed flexible airways.

    [Med Phys.] Development of a deformable lung phantom with 3D-printed flexible airways.
    3차원 프린팅 기술을 접목하여 변형 가능한 폐 팬톰 개발 연구

    가톨릭대, University of California Davis School of Medicine / 신동석, 서태석*, Yamamoto T*

  • 출처
    Med Phys.
  • 등재일
    2020 Mar
  • 저널이슈번호
    47(3):898-908. doi: 10.1002/mp.13982. Epub 2020 Jan 20.
  • 내용

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    Abstract
    PURPOSE:
    Deformable lung phantoms have been proposed to investigate four-dimensional (4D) imaging and radiotherapy delivery techniques. However, most phantoms mimic only the lung and tumor without pulmonary airways. The purpose of this study was to develop a reproducible, deformable lung phantom with three-dimensional (3D)-printed airways.

    METHODS:
    The phantom consists of: (a) 3D-printed flexible airways, (b) flexible polyurethane foam infused with iodinated contrast agents, and (c) a motion platform. The airways were simulated using publicly available breath-hold computed tomography (CT) image datasets of a human lung through airway segmentation, computer-aided design modeling, and 3D printing with a rubber-like material. The lung was simulated by pouring liquid expanding foam into a mold with the 3D-printed airways attached. Iodinated contrast agents were infused into the lung phantom to emulate the density of the human lung. The lung/airways phantom was integrated into our previously developed motion platform, which allows for compression and decompression of the phantom in the superior-inferior direction. We quantified the reproducibility of the density (lung), motion/deformation (lung and airways), and position (airways) using breath-hold CT scans (with the phantom compressed and decompressed) repeated every two weeks over a 2-month period as well as 4D CT scans (with the phantom continuously compressed and decompressed) repeated twice over four weeks. The density reproducibility was quantified with a difference image (created by subtracting the rigidly registered baseline and the repeated images) in each of the compressed and decompressed states. Reproducibility of the motion/deformation was evaluated by comparing the baseline displacement vector fields (DVFs) derived from deformable image registration (DIR) between the compressed and decompressed phantom CT images with those of repeated scans and calculating the difference in the displacement vectors. Reproducibility of the airway position was quantified based on DIR between the baseline and repeated images.

    RESULTS:
    For the breath-hold CT scans, the mean difference in lung density between baseline and week 8 was -1.3 (standard deviation 33.5) Hounsfield unit (HU) in the compressed state and 0.4 (36.8) HU in the decompressed state, while large local differences were observed around the high-contrast structures (caused by small misalignments). By visual inspection, the DVFs (between the compressed and decompressed states) at baseline and last time point (week 8 for the breath-hold CT scans) demonstrated a similar pattern. The mean lengths of displacement vector differences between baseline and week 8 were 0.5 (0.4) mm for the lung and 0.3 (0.2) mm for the airways. The mean airway displacements between baseline and week 8 were 0.6 (0.5) mm in the compressed state and 0.6 (0.4) mm in the decompressed state. We also observed similar results for the 4D CT scans (week 0 vs week 4) as well as for the breath-hold CT scans at other time points (week 0 vs weeks 2, 4, and 6).

    CONCLUSIONS:
    We have developed a deformable lung phantom with 3D-printed airways based on a human lung CT image. Our findings indicate reproducible density, motion/deformation, and position. This phantom is based on widely available materials and technology, which represents advantages over other deformable phantoms.

     

    그림. 본 연구에서 개발한 변형가능 기도 모델과 이를 탑재한 폐 팬톰

     


    Author information

    Shin DS1,2, Kang SH3, Kim KH1,2, Kim TH1,2, Kim DS1,2, Chung JB3, Lucero SA4, Suh TS1,2, Yamamoto T5.
    1
    Department of Biomedical Engineering, Department of Biomedicine and Health Sciences, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea.
    2
    Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, 06591, Republic of Korea.
    3
    Department of Radiation Oncology, Seoul National University Bundnag Hospital, Bundang, Gyeonggi-do, 13620, Republic of Korea.
    4
    Department of Biomedical Engineering, University of California Davis, Davis, CA, 95616, USA.
    5
    Department of Radiation Oncology, University of California Davis School of Medicine, Sacramento, California, 95817, USA.

     

    이달의 연구자 바로가기

  • 키워드
    deformable image registration; deformable phantom; flexible airways; three-dimensional printing
  • 연구소개
    본 논문은 가톨릭대학교와 UC Davis와의 공동연구를 통해 학계 최초로 3D 프린팅을 이용한 변형가능 기도(airway)가 부착된 변형 폐 팬톰을 개발한 연구입니다. 4차원 CT 및 breath-hold CT 스캔을 사용하여 각각 4주 및 8주간 밀도/움직임/변형/위치에 대한 재현성 평가를 수행하였으며, 결과적으로 개발된 팬톰의 재현성에 문제가 없다는 것을 확인하였습니다. 본 개발된 팬톰은 유연한 기도 모델을 탑재하고 있기 때문에, 폐암 방사선 치료 시 발생할 수 있는 기도의 움직임과 변형으로 인한 선량적 불확실성을 검증할 수 있는 유용한 도구로 사용될 수 있습니다. 또한, 제안한 팬톰은 복잡한 구조의 기도모델을 탑재하였음에도 불구하고, 간단한 방법 및 손쉽게 구할 수 있는 재료들로 제작되었습니다. 이러한 점들은 기존 변형 폐 팬톰들과 비교할 때 더 유용한 장점을 가지고 있음을 나타냅니다.
  • 편집위원

    Flexible한 3D 프린팅 팬텀을 사용한 Lung Phantom을 이용하여 호흡
    에 따른 모션을 연구한 점이 흥미롭습니다.

    2020-04-27 17:23:26

  • 편집위원2

    본 논문은 폐기도의 움직임을 고려한 4차원 영상획득과 방사선치료 빔 전달 기술을 연구하기 위해 3차원 프린팅 기술을 이용한 변형 가능한 폐 팬톰을 개발하는데 있다. 3차원 프린팅 기술을 접목한 변형 가능한 폐 팬톰은 방사선치료 전과정 동안 환자의 호흡 움직임이나 체중 변화, 중양 축소 등을 고려한 적응방사선치료(Adaptive Radiation Therapy, ART) 검증에 적극 이용함으로써 폐암 방사선치료 향상에 일조할 것으로 사료됩니다.

    2020-04-27 17:23:38

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