PTW is the global market leader in radiation medicine quality assurance and a specialist for manufacturing and supplying high-quality product solutions for radiotherapy, diagnostic radiology, nuclear medicine and health physics.

In 1922 PTW-Freiburg was founded to produce and market a revolutionary new electromechanical component for measuring very small electrical charges. Today PTW is the global market leader in radiation medicine quality assurance and a specialist for manufacturing and supplying high-quality product solutions for radiotherapy, diagnostic radiology, nuclear medicine and health physics. PTW-Freiburg operates one of the most busiest Secondary Standard Dosimetry Laboratories for radiological calibrations in the world, accredited by the PTB, the National Laboratory in Germany and is a member of the IAEA/WHO Network of SSDLs.

The quality of X-ray images is influenced by a number of parameters. To maintain a consistent performance of X-ray installations, quality checks have to be conducted regularly. The various components of the imaging chain are ideally tested independently to identify malfunctions and eliminate those detected easily. PTW offers a variety of diagnostic test tools for different X-ray equipment to avoid creeping deficiencies, to test proper functioning of the X-ray devices and to reduce patient exposure and costs for X-ray departments.

Furthermore PTW's "Code of Practice -- Constancy tests of X-ray equipment in diagnostic radiology" defines in an easy and compact way how to perform quality control measurements on different diagnostic X-ray installations. This document is a practical guideline for performing regular constancy tests and to ensure consistent quality in diagnostic radiology. The document is based on international standards and includes the description of test procedures for quality checks of any X-ray and film developing equipment. The necessary equipment for measuring main parameters, acceptable limits as well as adequate measurement protocols are mentioned accordingly. The "Code of Practice" bases on actual standards and because of its great success  it is available in eight different languages (German, English, French, Spanish, Portuguese, Russian, Chinese, Japanese)!