Airway ventilation state calibration system and system for predicting airway deformation during sleep

A model generating method comprising:

• a nasal-cavity model generation step of:
• extracting pixels having pixel density values from three-dimensional image data on a nasal cavity of a subject, the extracted pixels having pixel density values within a range defined between a first pixel density value and a second pixel density value larger than the first pixel density value, the first pixel density value being approximate to a pixel density value of air, and
• generating a nasal cavity model based on the three-dimensional image data composed of the extracted pixels, the nasal cavity model being a three-dimensional model of the nasal cavity;
• a simulation step of calculating a nasal cavity resistance through fluid analysis using the nasal cavity model generated in the nasal-cavity model generation step;
• and
• an adjustment step of adjusting at least the second pixel density value for the pixels to be extracted for generation of the nasal cavity model in the nasal-cavity model generation step until the nasal cavity resistance calculated in the simulation step becomes equal to a nasal cavity resistance actually measured with a nasal-cavity draft gauge, wherein the second pixel density value is adjusted by:
• incrementing the second pixel density value when the nasal cavity resistance calculated by the nasal-cavity resistance calculator is larger than the actually-measured nasal cavity resistance, or
• decrementing the second pixel density value if the nasal cavity resistance calculated by the nasal-cavity resistance calculator is smaller than the actually-measured nasal cavity resistance.

A method for predicting airway deformation in a sleeping state, the method comprising:

• a nasal-cavity model generation step of:
• extracting pixels having pixel density values within a specific range from three-dimensional image data on a nasal cavity of a subject, the extracted pixels having pixel density values within a range defined between a first pixel density value and a second pixel density value larger than the first pixel density value, the first pixel density value being approximate to a pixel density value of air, and
• generating a nasal cavity model based on the three-dimensional image data composed of the extracted pixels, the nasal cavity model being a three-dimensional model of the nasal cavity;
• a simulation step of calculating a nasal cavity resistance through fluid analysis using the nasal cavity model generated in the nasal-cavity model generation step;
• an adjustment step of adjusting at least the second pixel density value for the pixels to be extracted for generation of the nasal cavity model in the nasal-cavity model generation step until the nasal cavity resistance calculated in the simulation step becomes equal to a nasal cavity resistance actually measured with a nasal-cavity draft gauge, wherein the second pixel density value is adjusted by:
• incrementing the second pixel density value when the nasal cavity resistance calculated by the nasal-cavity resistance calculator is larger than the actually-measured nasal cavity resistance, or
• decrementing the second pixel density value if the nasal cavity resistance calculated by the nasal-cavity resistance calculator is smaller than the actually-measured nasal cavity resistance;
• a conversion equation generation step of generating conversion equations by an optimization procedure using three-dimensional models of upper airways of a plurality of subjects in waking states and three-dimensional models of the upper airways of a plurality of subjects in sleeping states, the conversion equations converting location information on a specific site of an upper airway in a waking state into location information on the specific site in a sleeping state;
• and
• an estimation step of estimating location information on the specific site of the upper airway of the subject in a sleeping state by assigning location information on the specific site of the upper airway of the subject in a waking state to the generated conversion equations.