Device (10 30 50 70) for calibration of a quantitative computed tomography apparatus, which includes a body (12 32 52 72) and several known-density elements (13 33 53 73) attached to the body and made of different materials and in different densities from each other and different from the body. The body (12 32 52 72) is configured to be placed in the mouth or on another part of a persons head, with the known-density elements (13 33 53 73) arranged in the region of the persons teeth. The device enables a quantitative computed tomography apparatus to adjust its calculations so as to convert the radiodensity units of the tomographic image into bone mineral density units, by knowing the exact densities of certain points of the image, corresponding to the points where the known-density elements (13 33 53 73) are located.
