[en] The application of radiation in human health, for both diagnosis and treatment of disease, is an important component of the work of the IAEA. The responsibility for the increasing technical aspects of this work is undertaken by the medical physicist. To ensure good practice in this vital area, structured clinical training programmes are required to complement academic learning. This publication is intended to be a guide to the practical implementation of such a programme for diagnostic radiology. There is a general and growing awareness that radiation medicine is increasingly dependent on well trained medical physicists based in the clinical setting. However, an analysis of the availability of medical physicists indicates a large shortfall of qualified and capable professionals. This is particularly evident in developing countries. While strategies to increase academic educational opportunities are critical to such countries, the need for guidance on structured clinical training was recognized by the members of the Regional Cooperative Agreement (RCA) for Research, Development and Training related to Nuclear Sciences for Asia and the Pacific. Consequently, a technical cooperation regional project (RAS6038) under the RCA programme was formulated to address this need in the Asia-Pacific region by developing suitable material and establishing its viability. Development of a clinical training guide for medical physicists specializing in diagnostic radiology started in 2007 with the appointment of a core drafting committee of regional and international experts. The publication drew on the experiences of clinical training programmes in Australia and New Zealand, the UK and the USA, and was moderated by physicists working in the Asian region. This publication follows the approach of the IAEA publication Training Course Series No. 37, Clinical Training of Medical Physicists specializing in Radiation Oncology. This approach to clinical training has been successfully tested in Thailand, with two other Member States currently undergoing testing, and is believed to be applicable to the medical physics community in general.