X-Ray Tomography

This movie from the Dornelas laboratory shows how X-ray tomography works.

X-ray microtomograhy or micro computed X-ray tomography is a technique used to obtain 3D images containing both external and internal information of an object. This technique is commonly used for animal samples, but it has been increasingly used to obtain 3D images from plants. The way the technique works is similar to a hospital CAT-scan, but in a smaller scale and with increased resolution. A source of X-ray illuminates an object and a detector captures an image. Hundreds of images are acquired while the object rotates. These images are used by a computer program to reconstruct a stack of virtual cross section slices through the object. These slices can be obtained in many different orientations to provide the information needed. Additionally, a stack of these virtual cross sections can be combined by other computer programs to produce a 3D rendering of the object that was imaged. These 3D reconstructions can also provide information on the internal structure of the sample. Commercially available equipments can also produce images using a fixed object and a moving x-ray source. Some of these machines are so fast that a complete scanning can be performed in less than 10 minutes. This allows the imaging of entire small plants or delicate samples such as freshly collected flowers. As the technique is non-destructive and generally does not require further sample preparation, rare fluid-preserved museum samples can also be imaged and returned without damage. This technique is extremely useful to obtain detailed 3D descriptions of plant structures contributing to the studies of plant development and evolution. The InnerWorld of Passionflowers showcases the work of Marcelo Dornelas and his research group at Universidade Estadual de Campinas in Brazil.