Ultrasound Physics Flash Cards

Three interactive concept cards demonstrating how physics education can move beyond static memorization. Each card teaches a foundational SPI exam concept through direct manipulation and discovery.

Full Series Overview

This demo showcases three interactive concept cards sampled from across the SPI exam domains. Each card features a different interaction pattern, and any of these formats can be adapted to cover additional topics.

Domain 1

23% of SPI

Physical Principles

Acoustic Parameters, Propagation Speed, Attenuation and Half-Value Layer, Acoustic Impedance, Reflection and Refraction, Range Equation

Demo Card 1 Demo Card 2

Domain 2

7% of SPI

Ultrasound Transducers

Piezoelectric Effect, Transducer Types (linear, curved, phased), Bandwidth and Damping, Beam Characteristics

Domain 3

26% of SPI

Image Optimization

B-Mode Formation, Axial/Lateral/Elevational Resolution, Time Gain Compensation, Artifacts (reverberation, shadowing, enhancement, mirror), Harmonic Imaging

Domain 4

34% of SPI

Doppler Principles

Doppler Effect and Angle, CW vs PW Doppler, Spectral Analysis, Color and Power Doppler, Aliasing and Nyquist, Hemodynamics

Demo Card 3

Domain 5

10% of SPI

Quality Assurance and Safety

Bioeffects (thermal, mechanical), ALARA Principle, TI and MI Indices, Phantom Testing

Interaction Types

Slider
Parameter manipulation. Adjust values and watch relationships change in real time.
Builder
Drag, swap, or combine elements to construct scenarios and observe outcomes.
Scenario
Animated clinical simulations with adjustable conditions.
Quiz
Identification challenges. Classify, match, or diagnose.

The three demo cards below showcase Slider, Builder, and Scenario types respectively.

Acoustic Parameters

SPI Domain 1 | Physical Principles

Sound waves in tissue have measurable properties: frequency, wavelength, period, and amplitude. In diagnostic ultrasound, the transducer sets the frequency; everything else follows. Move the controls below to see how these parameters are linked.

wavelength = speed / frequency
0.31 mm = 1540 m/s / 5.0 MHz
Wavelength
0.31 mm
Period
0.20 µs
Propagation Speed
1540 m/s
Frequency
5.0 MHz
1 MHz 15 MHz
5.0 MHz

Acoustic Impedance and Reflection

SPI Domain 1 | Physical Principles

Acoustic impedance is a tissue's resistance to sound propagation. When sound hits a boundary between two tissues with different impedances, part of the beam reflects and part transmits. The greater the mismatch, the stronger the echo.

42.8%
Reflected
|
57.2%
Transmitted
R = ((Z2 - Z1) / (Z2 + Z1))2
R = (( 7.80 - 1.63 ) / ( 7.80 + 1.63 ))2 = 0.428
Z = density × speed | Impedance values are pre-calculated from published tissue densities and propagation speeds. Units: MRayls (megarayls).

Doppler Effect and Angle Dependence

SPI Domain 4 | Doppler Principles

The Doppler effect measures blood flow by detecting frequency shifts in reflected ultrasound. The critical variable is the angle between the beam and the direction of flow. Small angle changes produce large signal changes.

Doppler Frequency Shift
2,755 Hz
fd = (2 × f0 × v × cosθ) / c
fd = (2 × 5.0 MHz × 0.60 m/s × cos(45°) ) / 1540
cos(45°) = 0.71
0°
60° max
90°
45° Acceptable