This book will give an overview of the theory of mammography and mammographic equipment and recommendations for testing such equipment. The book will be a revision and update of the existing report entitled 'IPEM report 89: The commissioning and routine testing of mammographic x-ray systems' (version 3). It will cover all aspects of the physics of mammography, including new technologies that the existing report does not cover and the testing requirements for these. IPEM Report 89 is a valuable document for medical physicists working in mammography. Not only does the current NHS breast screening programme (NHSBSP) protocol for digital mammography systems require users to refer to IPEM Report 89, it contains a lot of information and theory not easily found elsewhere and is an important reference for physicists working outside of the breast screening programme. However, the report was last published in 2005 and since then technology has changed dramatically. This update will provide a much-needed refresh of the existing report with the inclusion of now almost universally adopted full field digital technology as well as new techniques that are becoming widely available: digital tomosynthesis and contrast enhanced spectral mammography. The chapters detailing obsolete technology and methods will also be removed.