Introductory Biomedical Imaging

X-Ray Imaging Simulations

Conventional radiography and computed tomography (CT) are closely related techniques. Images are generated by detecting X-rays that traverse a patient positioned between a source and a detector. X-ray transmission is high for radiolucent regions of the body, such as the lungs, which lack X-ray absorbing structures. In contrast, X-ray transmission is low for radiopaque regions, such as bone. In X-ray images, radiolucent areas appear black, and radiopaque areas appear white. In conventional radiography, each image point reflects summed X-ray attenuation along an associated straight-line trajectory between the source and detector. The resulting “projection” images lack depth information and suffer from structural superposition. In contrast, in CT, images are created by collecting projections at many viewing angles and using the different views to reconstruct high-resolution, depth-preserving two-dimensional slices and three-dimensional images of anatomical structures, including soft tissue. Conventional radiography has many uses, including detecting broken bones, cavities, and various cancers. CT also has many uses, including rapid emergency assessments, cancer diagnosis and treatment, and in conjunction with radionuclide imaging to create hybrid structural/functional images. Both conventional radiography and CT are notable for providing anatomic (i.e., structural) information.

The following simulations explore the foundations of X-ray imaging and how X-rays are used to create both planar and tomographic images. The simulations are listed in the recommended order of performance. Each simulation includes a home page from which the simulation can be run, together with links to simulation-specific Information, Background, and Activity documents.