Quality assurance of ultrasound systems: current status and review of literature.

Diagnostic ultrasound (US) images can be obtained from a quality device, in optimal working conditions, combined with the capable actions of the operator in tweaking the equipment's characteristics. The quality assurance (QA) is the topic of this review article, and it is addressed in an US practice through proper selection of the equipment when purchasing, and through care and preventive maintenance of the machine for ensuring accurate performance. For optimal US system functioning, QA steps carried out on the basis of a scheduled program are needed in any US practice or department. It is critical to confirm in a semiannual or annual basis that the image quality is maintained according to standards and any subtle change in equipment's functioning is detected and amended at an early stage. The use of test objects (also called US testing phantoms) is required above the basic level of QA testing. The scope of this review article is to inform the US user about necessary QA knowledge and at the same time, present the state of the art of the most suitable test methods for US QA. We referred to relevant publications, selected after performing a systematic literature search of the MEDLINE, EMBASE and COCHRANE databases, and also to the standards established by authoritative international societies.