CGT (Clinical Guidance Tree) Viewer

CGT Logo

See the download page to obtain this program


The CGT project ('The Development and Evaluation of A Computerised Clinical Guidance Tree for Benign Prostatic Hyperplasia and Hypertension') was funded by the Chief Scientist's Office in Scotland from March 2000 to June 2003. Richard Bland was the chief designer of the CGT system, Claire Beechey was the main implementer, and Dawn Dowding (now at the University of York) was the driving force behind the project. The clinical guidance trees were mainly designed by Pat Thomson and Claire Beechey (University of Stirling), Chris Mair (Forth Valley Primary Care Research Group), and Joanne Protheroe (University of Manchester).


The CGT Viewer is a graphical application that allows the user to explore a guidance tree through several phases. The demonstration examples provided with the tool include benign prostatic hyperplasia (swelling of the prostate), hypertension (high blood pressure), influenza vaccination, and menorraghia (excessive bleeding during periods). However, the Viewer is a general purpose tool that can be used with decision trees for any application. For example, the AD/IT tool (Abstract Decision/Interactive Trees) is also provided with some small non-medical demonstrations.

The example screenshots below are taken from the hypertension demonstration.


Warning The decision tree examples provided with the viewer are for demonstration purposes only. They must not be used as the basis of any real decisions by the user.

The CGT Viewer is provided as an executable installer for Microsoft Windows. Run cgt-2.8.exe and follow the installation instructions. The viewer is installed under the name 'Clinical Guidance Tree'. The code and examples are installed in C:\Program Files\CGT by default. The Microsoft Java Virtual Machine is also installed if not already present.

The program has been tested only on Windows XP and 7. It is likely to run successfully on later versions of Windows. It has not been tested on Windows Vista.

The code has been developed and packaged on a system with the latest Microsoft security patches and the latest Symantec anti-virus software. To the best of the authors' knowledge it is free from viruses and other malware.

Because the CGT Viewer relies on features in Microsoft Windows, certain aspects may need to be selected using Internet Options in the Control Panel, or using Tools/Internet Options/Advanced in Microsoft Internet Explorer. The Multimedia section needs to have 'Play animations in webpages' selected.

As the program runs, it logs user activities into a database file. (In clinical practice, a healthcare professional would later analyse this statistically.) The database is Log2.mdb in the same directory as you installed the CGT viewer. If the demonstration trees are used with the viewer, certain control files are written to the tree folders. It follows that anyone who uses the viewer requires write access to Log2.mdb file and to the trees folder.

If you wish to keep the viewer history private, ensure that only you can read the database file. After considerable use, the database may grow unacceptably large. Re-install the CGT viewer to re-initialise the database.


The University of Stirling retains all rights in this program. However, the University grants free use of this program for non-commercial research purposes.

This program is distributed in the hope that it will be useful but without any warranty, without even the implied warranty of merchantability or fitness for a particular purpose.


Version 1.0 .. 2.7: Internal versions, Claire Beechey, March 2001 .. June 2003

Version 2.8: First public version, Claire Beechey and Ken Turner, 19th October 2007

Version 2.9: Ken Turner, 22nd October 2008:

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Last Update: 18th July 2016