How does increasing the number of focal zones affect imaging?

Increasing the number of focal zones primarily affects the frame rate by decreasing it. Each additional focal zone requires the system to send and receive ultrasonic pulses from multiple depths, which leads to an increase in the time needed to capture the entire image. This results in a reduction of the frame rate, meaning that the images are updated less frequently.

While axial resolution may seem like it could improve with more focal zones, it is primarily determined by the bandwidth of the transducer rather than the number of focal zones. Similarly, depth of field and lateral resolution are influenced by other factors, including transducer design and beam characteristics, rather than solely by increasing focal zones. Thus, while those factors have their complexities, the key effect of adding focal zones is the decrease in frame rate due to the extended time required for data acquisition.