In this study, the method to measure the deformation at the surface and inside of a mattress was developed. The mattress with contrast media on and in it was manufactured, and the manikin in imination of the shape of the human trunk, of which the weight was equivalent to the human one, was manufactured by photo fabrication. The mattress with the manikin on it were photographed by X-ray CT. It was confirmed that the CT images had the phantom of contrast media and the mattress deformation state could be visualized. The coordinates of positions equivalent to the centers of gravity of contrast media were acquired from image processing. This process enabled us that deformation state of the mattress was evaluated using numerical values. The plane shape at the mattress surface contacting the manikin was almost the same as the shape of the manikin. Thus, the digitizing precision of our method was estimated by comparing the shape of the manikin with the digitized result, showing the precision was about 2.4mm.
