Medical ultrasonic imaging: An overview of principles and instrumentation

Recent advances in electronics and digital processing techniques have significantly improved conventional ultrasonic imaging systems and allowed the development of new and sophisticated scanning methods. As a result, ultrasonic imaging devices have become an important modality for the clinical radiologist, complimenting the images obtained from X-ray and nuclear cameras. A particular advantage of ultrasonic waves is that they are nonionizing, thus presenting less risk to both patient and examiner. This paper presents some of the basic principles of ultrasonic propagation in tissue and how those principles impact the design of imaging devices. The characteristics of both the B- scan and C-scan techniques are described along with a summary of various scan formats that are currently available. Examples of B-scan and C-scan instruments are presented along with their relative advantages, limitations, and current usage;representative images are presented whenever possible. This paper concludes with a description of some new research developments in this rapidly emerging technology.