Waves and energy propagation are central to medical sonography. Amplitude (A), frequency (v) and phase shift (p) describe a given wave on an x-y plot. Since a wave oscillates with respect to time, the relevant independent variable is time (t). The overall equation is y = A*sin(vt + p). Variable "y" describes wave behavior over time, taking into account amplitude, frequency and phase shift.
Medical sonography gives an image of soft tissues. Abnormal growths that are not sufficiently dense to show up under X-ray analysis are visible through ultrasound techniques. Understanding how soft tissue absorbs, reflects and refracts sound vibrations is important in programming the software that interprets sonogram signals into comprehensible images.
Mathematics and an understanding of electric current are necessary. Resistors, capacitors, LED physics and electrical noise are all necessary for proper instrumentation design.