Medical Phisics (1 Viewer)

[Angle]

Can anyone please help me with the answers to the following dot points:
explain why MRIs can be used to:
detect cancerous tissues
identify areas of high
blood flow
distinguish between grey
and white matter in
the brain

.explain why different types of optical fibres will affect the image produced by an endoscope.

.describe how ultrasound is used to measure bone density

By the way which book are you using for the medical physics option.

Thanks heaps , Angle

 

[Angle]

Medical *Physics*

Sorry for the wrong spelling of Physics in the previous post

 

[damy]

Re: Medical Physics

You can find the answer to all those questions in Physics Contexts 2

I'll summarise them here though

- cancerous tumours obtain diff amounts of water from normal tissue or are often surrounded by some kinda watery fluid so they stand out clearly in MRI scans

-blood contains water,when there is more blood,there is more water therefore MRI can detect and analyse high blood flow

-grey matter of brain contains more water than the white matter so MRI can distinguish between them

-there is two types of optical fibre,coherent and incoherent...I'm pretty sure the book you're using explains why only coherent is used for imaging

-the velocity at which ultrasound travels depends on the density of the matter and the velocity at which the pulse of ultrasound travels from one side of the bone to another can be used to estimate the bone density

 

[Angle]

Thanks.

Thanks Damy,
The only book that I have for medical physics is "MACMILLAN PHYSICS 2" .In class we are using "Jacaranda" which does not have the medical physics option. Once again thanks for your answer .

 

[kckeven]

re: the velocity at which ultrasound travels depends on the density of the matter and

the velocity at which ultrasound travels depends on the density of the matter and the velocity at which the pulse of ultrasound travels from one side of the bone to another can be used to estimate the bone density

While this is true it is not to my knowledge the way that bone density is measured in ultrasound. Here is a quick run down of what i have been told:

Not all body tissue transmits sound with the same degree of ease. The accoustic impedence (Z) of a material is a measure of its opposition to the propagation of sound waves.
Z=pv
Z - accoustic impedence measured in rayls (1 rayl = 1 kg/m^2/s)
p - density of the medium measured in kg/m^3
v - velocity pf sound in the medium m/s

take a look at the table attached and u can that the densitys of body tissues and bones can be calculated.

But to do this the velocity and Z must be measured. Z is measured by measureing the intensity of the sound waves emitted and proportion reflected back. The velocity is then measured as the distance / time. Hope that is right :S and hope it helps.