Medical Physics dot points (1 Viewer)

[ToRnaDo]

"Describe how the principle of acoustic impedence and reflection and refraction are applied to ultrasound (Col 2 dot 4)"

Im stuck with this dot point :confused . Is there anyone do Medical Physics can help me with it???

 

[underthesun]

Because of different acoustic impedances for different body organs / structures, the reflected waves depend on the acoustic impedance of the structure that the waves are propagating to. Using this information, an ultrasound transducer producing waves objected onto a body will reflect and refract back the waves on different intensity and time. This information could be calculated by a computer to produce different brightness dots, for B-scan types, or wave charts for A-scan types.

Now, im just curious, what does the refraction part has to do with it? (Im thinking something to do with direction)

 

[Ragerunner]

i think because of the unflat nature of a body refraction will occur and send the ultrasound signals in other directions which can be a real mess.

 

[ToRnaDo]

Yeahh.. i dont know what the refraction part do either.. . I think it continues to go another tissues of the body. Thats all i guess and what happend next i have no idea???????????//

 

[underthesun]

Or since the wave is refracted, the wave won't reflect back to the same transducer. I got this on some website:

Refraction

If the ultrasound pulse strikes an interface at normal incidence, a percentage will be reflected back through the first medium, and a percentage will be transmitted into the second medium without a change in direction. However, if the pulse strikes an interface at oblique incidence, the transmitted portion of the pulse may be refracted. Refraction is often responsible for the misplacing of information in ultrasound images [2].

 

[underthesun]

Or how about refraction allows the machine to calculate the direction of the surface in which the wave reflects / refracts?