Programmable TGC in Ultrasound Receivers
The time gain control (TGC) in most diagnostic ultrasonic receivers is a monotonically increasing function of time relative to the transducer excitation. The TGC compensates for tissue absorption of ultrasound as a function of range. However, a monotonically increasing TGC cannot independently compensate for tissue absorption and variations in the acoustical impedance and effective reflecting areas at tissue interfaces. One approach to compensate for variations in echo producing parameters is to employ a more versatile TGC. A new design receiver employs TGC that can increase, decrease or not change the receiver gain over a useable 5 0 db dynamic range. The TGC can be programmed in 1 cm range steps for A- or TM-mode presentations or in 2 cm range steDS for scanning presentations.