Sunday, May 18, 2014

What is the difference between a traditional CT Scanner and a Spiral CT Scanner?




marshyanke


I know that a spiral produces thinner slices and perhaps in more detail, I am not really sure? I would like to better understand the science behind it? Also, could you respond with some understanding of MRI and Doppler scans as well? Could you provide some of the history of the above mentioned diagnostic tests? Thank you.


Answer
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.

Spiral CT scanning is just a new and advanced from of CT scanning: This is a newer type of CT scan, also known as a 'helical' CT scan. It is faster than a standard CT scan and gives an even more detailed picture of your organs and tissues, including blood vessels. This can make it useful for picking up very small tumours. It's called a spiral scan because the X-ray beam rotates around you during the scan in a spiral shape. This gives the radiographers a continuous picture, with no possible gaps between the 'slices' of the scan.

Can someone answer my questions about the 3-D printer?




Joey


Is there any limits to what it can make? Is it illegal to make certain things out of the 3D printer? If so,tell me. How much money is a 3D printer?If I put a puppy in the scanner, would it be able to replicate the puppy? How does the 3-D printer know if something should move or not?


Answer
Let me answer your questions one at a time:

1. Is there any limits to what it can make?
Right now, yes. In the future, no. The technology today is not advanced enough to make anything. The most common materials used now are plastic, resin, and recently the technology has grown to include metal. Food (lots of chocolate) has recently been printed as have organic materials such as stem cells. However, right now the biggest constraints of 3D printing is size. Soon one can conceivably print things as big as buildings, but for now most printers are relatively small (12in.X12in. though there are some much larger commercial printers). The future of 3D printing will also allow for printing on a molecular level, but for now the technology can only print in the micro scale.

2. Strictly speaking there are no laws against printing anything in 3D. However, laws exist that prohibit the manufacturing of certain goods and these apply to things that a 3D printer can conceivably make. An example of something that is illegal to print in the U.S. is a full gun. One can print parts of a gun legally, but cannot print a whole gun.

3. The cost of a 3D printer varies greatly. One can buy a 3D printer for the home for as little as $499. Commercial 3D printers cost much more and can run upwards of $30,000. With the continual advancement of the technology you can expect to see the prices drop as time goes on.

4. If you scan a puppy in 3D, a printer can print it in 3D. It would most likely be made out of plastic or resin though, not nice soft puppy fur.

5. 3D printers can print moving parts. When an item is programed into the software it maps out exactly where to lay down material. Because 3D printing is additive manufacturing it doesn't print the parts one by one, but instead prints the whole object layer by successive layer. If the programing is correct then moving parts can be included in the printed final product.




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