The National Library of Medicine of the US Department of Health and Human Services has
established the Visible Human Project with the goal of creating a digital atlas of the
human body. The data collected for this purpose currently include X-ray computed
tomography (CT), magnetic-resonance imaging (MRI), and digitized cryosectional images for
one male and one female cadaver. An overview of this project and information on its data
products may be found at <http://www.nlm.nih.gov/research/visible/visible_human.html>.
With permission from the
NLM, portions of the Visible Man CT and MRI data are
included on the Slicer Dicer CD-ROM. These data are provided solely for demonstration
purposes. The user is encouraged to explore these data in order to become familiar with
the operation of Slicer Dicer and to discover its usefulness in visual analyses of complex
volumetric data. The Visible Human data are well-suited for this purpose because almost
everyone is curious about human anatomy and knows enough to appreciate these data, even
without understanding the details of how CT and MRI data are collected or how they are
interpreted by medical professionals.
Limitations, and Restrictions
The Visible Human data samples included on the Slicer Dicer CD-ROM are provided
courtesy of the National Library of Medicine (NLM) of the US Department of Health and
Human Services. Use of these data is subject to copyright restrictions and other
limitations imposed by the Slicer Dicer Software License Agreement under which the Slicer
Dicer software and associated data products are distributed.
The Visible Human data are provided by the NLM on an interim basis and may be modified
substantially by NLM in subsequent versions.
About CT and MRI
CT and MRI are volumetric scanning techniques widely used in medicine as well as in
many non-medical settings, such as non-destructive testing and quality control in
X-ray computed tomography (CT, or CAT for computer assisted tomography) involves an
X-ray source and detector deployed on opposite sides of the specimen or patient. This
equipment is arranged in such a way that the X-ray beam can be rotated about one axis
while the specimen is translated parallel to that axis. In this way, a sequence of
transverse cross-sections are obtained, with X-ray images of each section digitally
recorded from many angles. Subsequently, algorithms derived from a mathematical procedure
called tomography are applied to reconstruct a three-dimensional matrix of values
representing the X-ray transmission properties in the volume occupied by the specimen.
The following image is a Slicer Dicer rendering derived from the CT sample data. It
includes a projected volume (maxima) rendered on the background surfaces and an isosurface
delineating the skull. A cutout has been used to cut away a portion of the skull and
reveal its interior.