COPYRIGHT
---------
This program is written by Kevin M. Rosenberg, M.D.

It is covered by the GNU General Public License (GPL) which
allows copying and modifying this code with restrictions. See the
file COPYING for complete details.

HISTORY
------

CTSim development began in 1983 while I was in medical school.  It was
written using Lattice C and MS-DOS. I used assembly language to write
directly to an IBM EGA video adapter.

In 1999, I ported CTsim to GNU/Linux. In April 2000, the source code 
for CTSim was published on the Internet.

STATUS 
------

The official home for CTsim is http://www.ctsim.org. From this site,
you can download the CTsim source code and use CTSim online using a
beowulf cluster.

I would be very pleased to have other developers join me in the
development of CTSim. Please see the TODO list for the most obvious
ideas.

In this release, the main issue that needs addressing is the inclusion
of old graphic library code. This code is not being used by
CTSim. Compilation warnings will occur in these files. Please ignore
these warnings. In the next major release of CTSim, there will be
support for interactive graphics. I just need to write the low-level
drivers to support X-window rather than IBM EGA hardware.

OVERVIEW
--------

CTSim simulates the collection of x-rays by a CT scanner. These x-rays
of objects are called projections or raysums.

Phantom objects are defined. Several built-in phantoms are included,
as well as an extension to load files of phantom definitions.

CTsim uses .sdf (standard data files) to represent 2-dimensional image
data. It uses a 32-bit floating-point pixel format. SDF is loosely
based on a image file format used by the Jet Propulsion Laboratory
(JPL). It supports multiple text labels per image.

THE PROGRAMS
------------

phm2sdf - generates an SDF image of a phantom object

phm2rs - Simulates the collection of CT data, or raysums, of a phantom
object

ctrec - Performs an CT reconstruction, also known as image
reconstruction from projections. Reads a raysum file and writes a SDF
file.

rs2sdf - Converts raysum data to a raw sinugram image

sdf2img - Converts an SDF file to a variety of 8-bit image formats

sdfinfo - Show statistics and history labels of SDF files

TYPICAL USAGE
-------------

When evaluating CT simulation, in general, these steps are followed:

Create a phantom image and viewable image file
  phm2sdf ...
  sdf2img ...

Simulate CT data collection and create a viewable image of raw raysums
  phm2rs ...
  rs2sdf ...
  sdf2img ...

Perform CT reconstruction and create viewable image file
  ctrec ...
  sdf2img ...

These functions are convert output image to a PNG file performed by
the CGI program ctsim.cgi which can be installed as described in
INSTALL file.

There is a sample shell script installed called 'sample-ctrec'.


CLOSING
=======

Please enjoy CTSim. I'd like to hear any feedback

Kevin M. Rosenberg, M.D.
kevin@rosenberg.net