Hokkaido University Research Profiles

Japanese
Information and Communication

Development of Mathematical Algorithms for Biomedical Optical Imaging

Development of a mathematical model for light propagation model inside biological tissues

A highly accurate and computationally efficient light propagation model is necessary for the progress of biomedical optical imaging. In this study, we have succeeded in constructing a fast solution method for the radiative transfer equation that describes light propagation with high accuracy. We are working on the advancement of an optical diagnosis and treatment using the proposed method.

Content of research

In this study, we are constructing a mathematical algorithm for biomedical optical imaging based on the radiative transfer equation. Our goal is to develop an imaging technique with excellent image resolution that can be applied to biological tissues and body parts where conventional imaging based on mathematical models cannot be applied. Until now, the numerical computational burden of the radiative transfer equation has been enormous, limiting its applicability to small-sized organisms. In this study, we have succeeded in developing a highly accurate and computationally efficient light propagation model by coupling the radiative transfer equation and the photon diffusion equation. Optical imaging based on the developed light propagation model can be applied to various biological tissues and sites. Currently, we are working on applying the model to the optical diagnosis of thyroid tumors in the human neck and the in-vivo evaluation of optical property values in biological tissues.

  • Near infrared rays
    Near-infrared light (light in the wavelength region of 700 nm ? 900 nm) can propagate deep into the body, and penetrate as far as the thickness of an adult male's hand, as shown in the figure.

  • Construction of a Propagation Model: Fast Solution of a Radiative Transfer Equation
    At the detection point where the light diffusion equation (DE) does not hold, the integrated light intensity Φ by the radiative transfer equation (RTE) agrees well with the coupled model (Hybrid) proposed in this study.

  • Light propagation in the human neck
    This is a simulation of the integrated light intensity distribution when light is irradiated from the front of the neck (top of the figure). Light with information about the thyroid gland is considered to be detectable.

Potential for social implementation

  • ・Photodiagnosis of thyroid tumors: We believe that a photodiagnosis is effective for those types of tumors that are difficult to identify using conventional methods.
  • ・Functional brain imaging: We believe that we can capture the dynamics of brain activity with higher accuracy than before.

Appealing points to industry and local governments

The optical imaging technology proposed by the researchers can be applied to small tissues such as skin as well as large areas such as the human neck, and is highly useful. We also expect to integrate light with heat and sound, and are considering joint research with researchers in thermal engineering and acoustic engineering, as well as with companies.

2022/5/27Released