What denotes the rows and columns of pixels in a digital ultrasound image?

• A. Matrix
• B. Bitmap
• C. Voxel
• D. Grid

Answer: (A)

A digital ultrasound image is a grid of samples arranged in rows and columns, which is called a matrix. Each intersection of a row and column holds a pixel value that represents brightness or color at that point. Thinking of the image as a matrix makes sense because it’s a precise, two-dimensional array of data that can be directly indexed and manipulated with math operations.

If we extend to three dimensions, the equivalent element is a voxel, which is why voxels aren’t used for 2D images. A bitmap describes how pixels are stored or displayed, but the fundamental way the rows and columns are organized is best described as a matrix. A grid is a more general term and doesn’t specify the data structure used to store pixel values.