Whats the diff between ct and pet scans?

A PET scan involves injecting a small amount of a radioactive chemical in a vein and then waiting for a period of time so it can be aborbed by tissues and organs. A PET will show you metabolic changes occuring in a organ or tissue.This is important because disease begins with funtional changes at the cellular level.A PET can dectect these changes very early where as CT does not show changes until there is damage to an organ or tissues.CT uses X_rays to take detailed pictures of the body.With CT sometimes a contrast agent is used to make it easier to see organs.The machines look the same but,give very different information.

I am not completly sure but I think that a cat scan is more of the brain and a Pet is of the cerebral cord. I know that a PET scan is newer, so I think that it gives a more 3d image.

A CT scan uses only images taken by like an Xray, the technology is far more superior and allows the doctor to see a more detailed image of the body than an xray. A PET scan uses images nuclear images that radiate after a nuclear material has been ingested by the patient. The images are taken from the position of the emission of positrons. Or the liquid that you ingest.

They are completely different technologies, and have different uses. A CT scan is essentially a complicated X-ray. The machine does x-rays from every angle then a computer puts the results together to form a three-dimensional image of your body. It's good for structure, you can see the anatomy very well in most cases. It's relatively cheap, and it's fast, especially with the new scanners.
A PET scan is something completely different. I don't understand how it works, to be honest, I don't have the physics background. It's a nuclear scan and requires a radioactive tracer (very low level, not harmful). What it is good for is looking at function, it's level of resolution is not as good as what you get with a CT scanner, but you can see which tissues are metabolically active, which can be very helpful if you're looking for, say, metastatic cancer. It also takes a lot longer to perform and is more expensive than a CT scan.

I don't recall anymore, but I do know that some scans can detect growths that the other scan can not.

A CT (computed tomography) scan also known as CAT (computed axial tomography) scan is an imaging technology using X-rays and computer tomography to generate 2-D or 3-D images. It is used to look at structures in the body. In the case of cancer, tumors are looked at. Quite detailed images can be captured using CT scans.

A PET (positron emission tomography) scan is a imaging technology where the patient is injected with a radioactive sugar. Cancer cells absorb this sugar more readily than normal cells. The sugar decays giving off radioactive particles which are detected by a scanning device. The cancer cells which absorbed most of the radioactive sugar will be giving off the most particles and show up brightly (if color) or dark spots if black and white. As mentioned, it is a useful tool for detecting metastases.

CT scans work similarly to x-ray and show structure and anatomy only and sometimes involve the use of a contrast. PET is geared to show metabolic function by use of a positron emitting radioactive glucose that is injected via an IV, most commonly used is F-18 (FDG). PET radiopharmaceuticals, which have a very short half-life, work with the bodies ability to metabolize glucose as effected areas will uptake the glucose more readily due to the high metabolic activity of cancer. Someone mentioned previously that the dose is of low radioactivity which is not true....actually with PET radiopharmaceuticals you are getting a greater exposure due to the high energy and very short half life which is the reason why the PET technologists take turns injecting patients. Their exposure is greater than say a general Nuc Med Tech...... PET and CT always work together (Which is why it is called PET/CT) as the CT will map out areas of concern when superimposed over PET. PET has the wonderful ability to show even the minutest areas of glucose uptake which leads to early cancer detection and treatment, much earlier than the ability of CT. CT can be used for most general radiology findings while PET is mainly used for cancer staging and restaging. Unfortunately, it is harder to get insurance to pay for PET scans than it is for CT unless you have a cancer diagnosis. PET/CT is obviously more expensive than just CT alone due to the cost of the radiopharmaceutical dose and time involved and you are technically getting 2 scans in one shot...........