This paper discusses the measurement of bubbles moving through a fluidized bed imaged with a double X-ray tomographic scanner. The scanner is made of 3 X-ray sources equipped with two rings of 90 CdWO4 detectors The fluidized bed has a diameter of 23 cm and is filled with a Geldart B powder The scanner measures the attenuation in two thin parallel slices separated by a small vertical distance This allows the estimate of the velocity of individual bubbles rising through the bed. Data arc collected at a frequency of 2500 Hz To remove the noise, data are averaged over 10 samples before tomographic reconstruction is performed, resulting in 250 independent frames per second From the measured bubble velocity and the passage time through the reconstruction planes, the vertical dimensions of the bubbles are found. This allows imaging of the real shape of the bubbles and calculation of the volume of each individual bubble