Physics p1

is a noninvasive, radiation-free imaging test that uses high-frequency sound waves to create real-time pictures of organs, soft tissues, and blood flow inside the body. It is commonly used to monitor pregnancy, diagnose medical conditions, and guide procedures like biopsies

Ultrasound (sonography)

is a form of energy which causes a mechanical disturbance in the form of vibration of molecules within a

Sound, Medium

It will then cause adjacent air molecules to vibrate, and these in turn will cause their neighbouring molecules to vibrate. This disturbance will spread through the air as a

Longitudinal wave

Types of UTZ Waves

Longitudinal/Compression, Transverse/Shear, Surface/Rayleigh

Primary type used in diagnostic ultrasound Particles vibrate parallel to the direction of wave propagation. Require a material medium (cannot travel in a vacuum). Produce alternating compressions and rarefactions.

Longitudinal Waves (Compression Waves)

Longitudinal Waves (Compression Waves) Examples

Abdominal ultrasound Obstetric ultrasound Echocardiography

Longitudinal Waves (Compression Waves) Characteristics

Fastest type of sound wave in soft tissue Travels through liquids, solids, and gases Used for all diagnostic medical ultrasound

Particles vibrate perpendicular to the direction of wave propagation. Travel only through solids under normal conditions. Do not propagate in fluids because fluids cannot support shear stress.

Transverse Waves (Shear Waves)

Transverse Waves (Shear Waves)

Characteristics

Slower than longitudinal waves

Used mainly in elasticity imaging rather than conventional B-mode imaging

travel along the surface of a solid, with particle motion following an elliptical path. Their energy decreases rapidly with depth beneath the surface

Surface or Rayleigh Waves

Surface or Rayleigh Waves Characteristics

Confined to the surface of solids Particles move in an elliptical motion Slowest among the three wave types Energy is concentrated near the surface

DIAGNOSTIC range

1-30 MHz

THERAPEUTIC Range

0.7 - 1.0 MHz

SURGERY Range

1-5 MHZ

INDUSTRIAL Range

25-400 kHz

MILITARY Range

20-50 kHz

Deep abdominal imaging, obese patients

1–3 MHz

Adult abdomen, obstetrics, pelvis

2–5 MHz

Small parts, vascular studies, pediatrics

5–10 MHz

Breast, thyroid, testes, musculoskeletal imaging

7–15 MHz

Ophthalmology, dermatology, superficial structures

15–30 MHz

AIR (at 32º F)

331 m/s

WATER (SEA) (at 77º F)

1531 m/s

SOLID (STEEL)

5200 m/s

EARTHQUAKES OCCUR AT INFRASONIC FREQUENCIES

INFRA SOUND BELOW 16 Hz -20Hz

The phase of the wave when the molecules are pushed together is called? and when apart

Compression. rarefraction

ACOUSTIC VARIABLES

Period, Wavelength, Amplitude, Frequency, Velocity

The time taken for one complete cycle to occur

Period, T (s or µs)

Length of space over which one cycle occurs

Wavelength (λ), (m or mm)

The maximum displacement that occurs in an acoustic variable. (depth

AMPLITUDE

in a sound wave refers to the rate of the vibration of the sound travelling through the air 1 Hertz= 1Cycle per second

Frequency

is the distance traveled by a given point on a wave in a given interval of time

SPEED/VELOCITY

Fat velocity

1450 m/s

Soft tissue velocity

1540 m/s

Muscle velocity

1580 m/s

Bone velocity

4080 m/s

Period Unit

s, μs

Wavelenght unit

m, mm

Amplitude unit

dB

Frequency Unit

Hz, MHz

Velocity Unit

m/s

What determines ultrasound speed?

speed changes depending on its MEDIUM frequency doesnt change no matter what medium

is the ability of a material to return to its original shape after being compressed or stretched

Elasticity

Higher elasticity (stiffer material) =

Higher speed of sound

Lower elasticity (less stiff material)

Lower speed of sound

a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.

DECIBELS

Sound power is the total airborne sound energy radiated by a sound source per unit of time

power

Watt (W)

Sl Unit

commonly used in diagnostic ultrasound

Miliwatt