Curriculum · SPI

Ultrasound Physics & Instrumentation

The physical foundation every sonographer must master: wave physics, pulse-echo imaging, tissue interaction, transducers, beams, resolution, and the signal path. Maps to the ARDMS SPI examination.

6 lessons · ~200 min · level: foundation

1. 1Acoustic Waves & Parameters~35 minWhat sound is, the seven acoustic parameters, the wave equation c = fλ, propagation speed, acoustic impedance, and the decibel scale.SPI
2. 2Pulsed Ultrasound & Axial Resolution~30 minPulse duration, spatial pulse length, PRF/PRP, duty factor, and how spatial pulse length sets axial resolution (SPL/2).SPI
3. 3Wave–Tissue Interaction: Reflection, Refraction, Scattering & Attenuation~35 minHow the pulse interacts with tissue: specular vs diffuse reflection and the reflection coefficient, Snell's law, Rayleigh scattering (f⁴), and attenuation (0.5 dB/cm/MHz) with the half-value layer.SPI
4. 4Transducers: Piezoelectricity, Damping & Arrays~35 minThe piezoelectric effect, how element thickness sets frequency, the damping–bandwidth–Q tradeoff, the quarter-wave matching layer, array types, and electronic focusing/steering.SPI
5. 5Beams & The Five Resolutions~30 minNear-field length (D²/4λ) and far-field divergence, and the five resolutions — axial, lateral, elevational, temporal, and contrast — with what improves each.SPI
6. 6Instrumentation & Image Formation~35 minThe pulse-echo signal path: the range equation (13 µs/cm), TGC vs gain vs output power, dynamic range/compression, pre- vs post-processing, the frame-rate tradeoff, harmonic imaging, and spatial compounding.SPI