Optimisation of patient protection and image quality in diagnostic radiology.

OBJECTIVE To determine the examination frequencies, quality of radiographic images and the entrance surface dose (ESD) in patients undergoing general radiographic examinations. DESIGN Prospective study on the device performance, film reject rate, patient dose, and image quality during the use of standard and fast speed film screen combination. SETTING Radiology Department of Kenyatta National Hospital, a referral, teaching and research hospital in Kenya. SUBJECTS A total of 837 adult and 229 paediatric patients undergoing diagnostic examinations were assessed for patient dose and image quality. INTERVENTIONS The X-ray tube output measurements and X-ray exposure parameters were determined. The patients ESD on standard 200 and fast 400 speed film screen combination was determined. The radiographic image quality was assessed. MAIN OUTCOME MEASURES The findings were compared with the international diagnostic reference levels (DRL's) for determination of dose optimisation in diagnostic radiography. RESULTS The relative frequency of examination was 80% and 20% for adults and paediatric patients respectively. The image quality improvement by 13% was achieved and patient dose reduction range of 31% to 77%. CONCLUSIONS The patient dose reduction and image quality was achieved through a quantitative quality control (QC) assessment of processes involved in producing radiographs. The study leads to the introduction of the concept of plan- do-check-act on QC results and optimise with a view of patient dose reduction. The department appreciated the value of a quality assurance (QA) programme and continues to collect data for establishment of DRL's.