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sonography
marveen craig, 2nd edition esentials of sonography& patient care
| Question | Answer |
|---|---|
| gray scale | display mode in which echo intensity is recorded as shades of gray or brightness |
| anechoic | well defined echogenic walls without internal echoes, echo-free(black) appearance on a sonographic image. |
| hyperechoic | this reflects sound with a bright intensity. term used to described echo-producing structure that are brighter than normal or brighter compared to adjacent structures |
| enhancement or increased through transmission | sound that travels through a fluid-filled substance and is not attenuated (diminished) |
| fluid-level | interface between two fluids with different acoustic characteristics. this level will change with patient position |
| echogenic | capable of producing an echo |
| heterogeneous | refers to an uneven echo pattern or reflections of varying echodensities, not uniform in texture or composition |
| homogeneoeus | completely uniform in texture or composition |
| hypoechoic | term used to describe low-level echoes that are not as bright as normal echoes within a structure or less bright then adjacent structures |
| infiltrating | usually refers to a diffuse disease process or metastatic disease |
| irregular borders | borders are not well defined, ill defined, or not present |
| isoechoic | term used to describe structures with the same relative echo density, very close to the normal parenchyma echogenicity pattern |
| loculated mass | well-defined borders with internal echoes; the septa may be thin (likely benign) or thick(malignant) |
| acoustic impedance | density of tissue times the speed of sound in tissues |
| amplitude | strength of the wave measured in decibels |
| attenuation | progressive weakening of the sound beam as it travels through body tissue, cause by scatter, absorption, and reflection |
| crystal | material within the transducer that converts electrical impulses into sound waves and vice versa |
| cycle | per-second frequency at which the crystal vibrates |
| decibel | a unit used to express the ratio of two amounts of acoustical signal power equal to 10 times the commom logarithm of ratio |
| focal zone | depth of the sound beam where resolution is highest |
| frequency | number of times the wave is repeated per second as measured in hertz; diagnostic applications of ultrasound use frequencies of 1-10 MHz |
| hertz | standard unit of frequency; equal to 1 cycle per second |
| interface | occurs whenever two tissues of different acoustic impedance are in contact |
| megahertz(MHz) | 1,000,000 Hz |
| piezoelectric effect | effect caused by crystals changing shape when in an electrical field or when mechanically stressed, so that an electrical impulse can generate a sound wave or vice versa |
| power | quantity of energy generated by the transducer (expressed in watts) |
| pulse repetition rate | the number of times per second that a transmit-receive cycle occurs (use scale button to change) |
| resolution | ability to distinguish between two adjacent structures |
| specular reflector | reflection from a smooth surface at right angles to the sound beam |
| transducer | a device capable of converting energy from one form to another;in sonography, from electrical energy to mechanical energy * electrical energy goes into area of interst |
| ultrasound | sound waves beyond the audible range;used to evaluate soft-tissue anatomic structures. *audible=20-20,000 hertz *ultrasound=above 20,000 hertz *subsonic=below 20 hertz |
| velocity | speed of the wave, depending on tissue density |
| wavelength | distance a wave travels in a single cycle |
| acoustic power | varies the amount of energy the transducer transmits to the patient |
| cineloop | system memory stores a limited number of images as a sequence to be replayed |
| electronic focusing | each crystal elements within a group is pulsed separately to focus the beam at a particular area of interest |
| frame rate | rate at which the image is refreshed in a real-time system display; dependent on frequency and depth |
| gain | measure of the strength of the ultrasound signal throughout the image |
| real-time | type of imaging in which the image is created so many times per second that a cinematic view of the tissue is obtained |
| time gain compensation(TGC) | individual pod controls that compensate for attenuation of the sound beam as it passes through tissue |
Created by:
lgibbs
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