What is the difference between an ordinary Xray, a CT Scan and a MRI scan ? - any Radiographers out there ?

Question

Which type of Xray tests for the density of the calcium in your bones ?

Answer 1

The X-ray and the CT scan both use x-rays.

The X-ray is rather like an ordinary photograph, only the x-rays pass through your body to expose the film behind you instead of the film being in the camera and hit by light waves that bounce off you. That's why the x-ray looks like a film negative: the more x-rays that pass through you, the more exposed is the film and the brighter the image. If you look at an x-ray of a lung with pneumonia, the x-rays pass through the fluid more easily than they do through lung tissue, and so the spaces filled with fluid show up as spidery white lines in the lung.

The CT scan is an x-ray "slice" of your body. It doesn't use film but x-ray sensors that send their signal to a computer as the x-ray transmitter spins around the body to scan a slice of you. Then it moves on to the next slice of you to scan that, sending the x-rays through you to the sensors that send the image to a computer that prints the image, and on it goes.

An MRI is a whole different animal. You are put into a very narrow tube--so narrow that some people have claustrophobia in it even though it is open at the foot and the head--that is filled with a very strong magnetic field. The magnetic field acts on the protons in your body, causing them to "line up" either toward your head or toward your feet, because that' the axis of the magnetic field. Now, the protons line up (actually, they have "spin," and it's more like lining up the axis of their spin) more or less randomly, that is, about half of them line their spins one direction, and the other half line their spins in the other, but not quite. A few more in any area will align their spins in one way, giving that area a slightly more magnetic moment in one direction than in the other. Those are the ones that the machine will detect when a radio frequency pulse resonant to protons is applied to the body. The protons will absorb the energy of that pulse, which the MRI scanner detects. This is called "T1," for "Time 1," the time of energy absorption, and this creates an field that the imager detects. The the protons radiate that absorbed energy at a specific wavelength (which all particles do), and the imager picks up that radiation, which researchers call "T2," for--you guessed it--"Time 2," the time of energy radiation. The MRI can "see" tissues much better than can an x-ray, which can't see soft tissues well at all, except in a few certain circumstances. The MRI uses coils in the tube the patient slides into to selectively apply the magnetic field and the RF pulses to different slices of the body, and it can do so with great precision.

The x-ray technique that can detect bone mineral density is a dual x-ray beam, called DEXA for Dual Energy X-ray Absorbtiometry. 2 x-ray beams of differing energy levels are directed toward the same bone or bones, and the bone's density is calculated from the amount of x-ray energy absorbed from each of the beams.

Answer 2

An X-Ray is simply passing x-rays through the body and evaluating the resultant image that develops on specialized film. Comparatively speaking, it's rather primitive technology compared to the CT (Cat) scan and the MRI.

The CT scan can be described as a computer enhanced 3-dimensional x-ray. It allows for the delineation and inspection of "slices" of tissue.

The MRI, or Magnetic Resonance Imaging, uses computer enhanced interpretations of intense magnetic fields to also delineate "slices" and 3-d images of tissues.

Answer 3

Xray is used to investigate the skeleton of the body in a 2dimensions. a ct scan (computerised tomography) uses cross-sectional x-rays to build up a 3 dimensional image of the brain or other organs of the body. MRI scan (magnetic resonance imaging) uses a large magnetic field and a computer to build a 3 dimensional image, it is used primarily in brain imaging as it can exploit the different magnetic properties of oxygenated and deoxigenated blood. click on the link to find an on line medical dictionary, this site is an excellent resource and should provide all the answers you need.

Answer 4

All are imaging equipment, mostly used by radiographers and radiologists, medical professionals.
Xray and CT scan use ionising radiation to produce images, while MRI uses magnetic field.
Xrays and CT Scan are good for bones and MRI is good for soft-tissues.

Answer 5

right im not a radiologist or anything like that, but ive had most of those scans and there is a slight difference, from what i can tell.

they all produce different sorts of images - xrays are good for looking at bone structure, MRIs are better for looking at tendons/organs etc etc

hmm this isnt really much use sorry!

Answer 6

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Answer 7

X-rays (or Röntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 to 30 000 PHz (1015 hertz). X-rays are primarily used for diagnostic radiography and crystallography. X-rays are a form of ionizing radiation and as such can be dangerous. In many languages it is called Röntgen radiation after the investigator of the radiation, Wilhelm Röntgen.

Computed tomography (CT), originally known as computed axial tomography (CAT or CT scan) and body section roentgenography, is a medical imaging method employing tomography where digital geometry processing is used to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. The word "tomography" is derived from the Greek tomos (slice) and graphia (to write). CT produces a volume of data which can be manipulated, through a process known as windowing, in order to demonstrate various structures based on their ability to block the X-ray beam. Although historically (see below) the images generated were in the axial or transverse plane (orthogonal to the long axis of the body), modern scanners allow this volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures.

Although most common in healthcare, CT is also used in other fields, for example nondestructive materials testing.

Magnetic Resonance Imaging (MRI), formerly referred to as Magnetic Resonance Tomography (MRT) or, in chemistry Nuclear Magnetic Resonance (NMR), is a non-invasive method used to render images of the inside of an object. It is primarily used in medical imaging to demonstrate pathological or other physiological alterations of living tissues. MRI also has uses outside of the medical field, such as detecting rock permeability to hydrocarbons and as a non-destructive testing method to characterize the quality of products such as produce and timber.[1]

The scanners used in medicine cost approximately USA$ 1 million per Tesla (T) and have a typical field strength of 0.3 to 3T, with several hundred thousand dollars paid per year just for maintenance.

Answer 8

A dexascan will measure the density in your bones