This work is devoted to the application of tomographic techniques for "X Ray Dynamic Defectoscopy" (XRDD). The XRDD method enables the on-line observation of material density variations with micrometric accuracy thanks to the good spatial resolution and sensitivity of the Medipix-1 detector. The single X-ray photon counting pixel detector Medipix-1 consists of a matrix of 64x64 square pixels of 170 m pitch and their read-out electronics. The test specimen is illuminated by X-rays during the loading process. Measured changes in transmission represent effective alterations in the specimen thickness, which are understood as weakening of the material due to volume voids resulting from loading stress. Volume voids in the specimen are projected onto a single two dimensional image. Variation in void density along the beam can be determined by tomographic methods. This paper studies the applicability of tomographic techniques for XRDD and presents results of preliminary experiments.