Experience has drawn attention to the needs and potential benefits to be derived from the implementation of effective quality assurance programmes. Several studies have indicated the many diagnostic radiological facilities produce poor-quality images and give unnecessary radiation exposure. An early indication of the existence of these problems was revealed by a medical surveillance programmeconducted in the USA by the national institute for occupational safety and Health in association with the department of Labor’s Pneumoconiosis compensation program. Trout et al. (49 ) found that, despite the prescreening of facilities and readers,44% of the facilities participating in the first round of examinations had from 10% to 40% of their submitted radiographs of inadequate quality for the diagnostic of pneumoconiosis. these inadequate images represented unproductive radiation exposure as well as unsatisfactory medical care.Some of the reasons for the inadequacy were related to poor equipment performance. An evaluation of preauthorization dental submitted to Pennsylvania Blue shield( a statewide medical insurance plan ) in the USA found that approximately 20% were unsatisfactory for reasons probably related to poor equipment performance ( 5 ) . Astudent of a number of general radiography facilities by the Du Pont Company ( Delaware,USA ) revealed that, on average,13% of the radiographs processed were rejected as being of inadequateq quality (16 ).An average of 9 % of radiographs taken had to be repeated. An analysis of the reasons for these rejections led to the conclusion that poor equipment performance was an important problem.