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physics
frequency, wavelength, propagation Speed
Question | Answer |
---|---|
axial resolution | the ability of an ultrasound transducer to distinguish two closely spaced structures separately that lie parallel to the direction of sound travel. Axial resolution is equal to spatial pulse length divided by two. |
beam divergence | the increase in width of a sound wave as it travels beyond the focal point. Transducer diameter, frequency and focusing affect beam divergencce |
lateral resolution | the ability of an ultrasound transducer to resolve two closely spaced structures that lie perpendicular to the sound beam |
near zone | the area of the sound beam that extends from the face of the transducer to the focal point |
period | the time it takes for a single cycle to occur |
pulse | a collection of cycles. usually 2 to 5 cycles make up one pulse in clinical imaging ultrasound |
pulse duration | the time of a single pulse |
resolution | the ability to separate two closely spaced structures. |
spatial pulse length | the length of a single pulse |
ultrasound transducer | a piezoelectric crystal that is able to convert electrical energy into sound energy and vice versa |
f | frequency |
Hertz (Hz) | 1 cycle per sec |
kilohertz (kHz) | 1000 cycles per second |
MegaHertz (MHz) | 1,000,000 cycles per second |
infrasound | less than 20 Hz |
Audible sound | 20 Hz to 20,000 Hz (20 kHz) |
clinical imaging | 2MHz to 10 MHz |
frequency | the number of wave cycles per second is |
One compression and one rarefaction occurring in one second represent | 1 hertz |
the frequency range for infrasound | less than 20 Hz |
the frequency range closest to the lower limit of ultrasound is | 20 kHz |
the frequency range for clinical ultrasound imaging is | 20 to 10 MHz |
frequency is determined by the | source |
frequency decreases, depth of penetration | increases |
frequency increases, depth of penetration | decreases |
frequency increases resolution | improves |
frequency decreases resolution | degrades |
increasing frequency | decreases wavelength, decreases spatial pulse length, decreases period, degrades resolution |
increase the frequency does not improve | depth of penetration |