An apparatus and method for controlling the quality of cylindrical or other geometrically regular-shaped products, such as tube or rounds, through high precision, continuous, real-time three-dimensional analysis of hot or cold products during their manufacture are disclosed. The apparatus includes multiple penetrating radiation sources and detectors. The apparatus is able to continuously and in real time perform a three-dimensional analysis of hot or cold products, detect cross-sectional and longitudinal flaws in the products, determine the processing steps causing the flaw, and modify the production process through feedback and/or feedforward control of the processing equipment. In performing the analysis on hot or cold products, the apparatus can determine the dimensional measurements of the products at other temperatures and take these measurements into consideration while controlling the manufacturing process in order to produce products of consistent dimensional quality.