Introductory Biomedical Imaging

Radionuclide Imaging Simulations

Planar and tomographic nuclear imaging are emission analogs of projection radiography and computed tomography (CT), respectively. They similarly use ionizing radiation. To generate an image, a patient is administered a radiopharmaceutical comprising a radioactive substance attached to a pharmaceutical. The radiopharmaceutical preferentially localizes, by design, to a particular site in the body, which becomes a source of gamma-ray photons generated by nuclear decay events. The gamma rays escape the body, ideally without interacting with body structures, and generate an image of the distribution of the radiopharmaceutical. Nuclear imaging typically assays for disease-associated changes in function, which are manifest as altered radiopharmaceutical localization The detection of emitted, rather than transmitted, radiation is one of several key differences between nuclear and X-ray-based imaging. Common applications include monitoring the increased metabolism of glucose analogs by cancerous cells, showing sites of metastasis, and the reduced metabolism of glucose analogs in regions of the brain affected by cognitive impairment. The best-known tomographic approach is positron emission tomography (“the PET scan”). Nuclear images generally have poorer resolution, but better contrast, than X-ray images. Both planar and tomographic nuclear imaging are notable for providing functional information and are often used in conjunction with radiography to create hybrid structural/functional images.

The following simulations explore the fundamentals of radioactivity and how radioactivity is 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.