Which component is necessary for a real-time B-mode scanner but is not present in an A-mode scanner?

Which component is necessary for a real-time B-mode scanner but is not present in an A-mode scanner?

• A. Clock
• B. Scan converter
• C. Transmitter
• D. Receiver

Answer: (B)

The question is about what makes real-time B-mode imaging possible visually, not just the physics of echoes. For B-mode you’re building a two-dimensional brightness image from echoes collected along many scan lines. The scan converter is the component that takes those raw echoes, organized by time and along each emitted line, and maps them into the display coordinates, assigning a brightness level to each pixel. It effectively turns a sequence of one-dimensional depth traces into a coherent 2D image that can be refreshed rapidly for real-time visualization. In A-mode you’re only displaying a single depth trace, amplitude versus depth, on one line—there’s no need to assemble multiple lines into a 2D image. So a scan converter isn’t required there. The transmitter, receiver, and clock are still essential in both modes: the transmitter emits the pulses, the receiver processes the echoes, and the timing is coordinated by the clock. But the unique piece that enables real-time B-mode images is the scan converter, which translates the raw line data into the full image on the screen.

The question is about what makes real-time B-mode imaging possible visually, not just the physics of echoes. For B-mode you’re building a two-dimensional brightness image from echoes collected along many scan lines. The scan converter is the component that takes those raw echoes, organized by time and along each emitted line, and maps them into the display coordinates, assigning a brightness level to each pixel. It effectively turns a sequence of one-dimensional depth traces into a coherent 2D image that can be refreshed rapidly for real-time visualization.

In A-mode you’re only displaying a single depth trace, amplitude versus depth, on one line—there’s no need to assemble multiple lines into a 2D image. So a scan converter isn’t required there. The transmitter, receiver, and clock are still essential in both modes: the transmitter emits the pulses, the receiver processes the echoes, and the timing is coordinated by the clock. But the unique piece that enables real-time B-mode images is the scan converter, which translates the raw line data into the full image on the screen.