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Diagnostic imagingYour doctor may order a variety of different diagnostic scans and tests to help monitor and diagnose your NHL. The variety of different scans is often confusing to patients, and many wonder why they are not getting one type of scan instead of another. The most important point to remember is that each type of scan has its purpose and place in treatment. No one scan type is superior to all the others because each serves a different purpose, and each is very valuable in its own right.
X-RayX-rays are the oldest type of diagnostic scan around, and they have been around since the late 1890's. X-ray images provide the doctor with an excellent image of the interior structures of the body. X-ray images 2 dimensional and are excellent for a variety of tasks, so they are the most widely used scan used in medicine in general. X-ray images are less useful in the diagnosis and monitoring of cancer because it does not provide enough 3D detail for monitoring. X-rays are very good for detecting fluid build up in major organs like the lungs ( pleural effusion ) Overall X-rays will not be a common choice for regular NHL monitoring or diagnosis.
CT scansCT or Computed Tomography (often called CAT for CT's are the most widely used scan because they allow the radiologist and doctor to look "inside" your body and see the structures that are there. They can see shape, size, and location of anything inside you. They provide far more detail than a simple x-ray image can. This is extremely important for finding tumours, and monitoring their growth, and seeing if they are threatening any nearby organs. Virtually all patients will undergo multiple CT scans throughout their journey with NHL. They are relatively inexpensive and give the doctors a great deal of information about what is going on. Even very small tumours can usually be spotted on a CT scan by an experienced radiologist. Since they have been around for a long time, there is a high degree of experience with them in the medical field so mistakes are less likely to happen.
Gallium scansGallium scans are very similar to PET scans. In fact due to the superiority of PET at detecting the smallest traces of cancer Gallium is quickly being replaced by PET as the scan of choice. Like PET Gallium is a radioactive substance. Tissues that are infected, or are cancerous have a very high affinity for Gallium and therefore it migrates to those tissues. This is often referred to as Gallium avid tissue. When the scan is performed those areas will light up quite vividly on the image. In general the patient will have the Gallium injection one day, then come back 3-4 days later for the actual scan. Once again, Gallium scans have their place in diagnostic imaging so even though PET are considered superior there are times when a Gallium scan is the preferred scan. Gallium is very good at finding inflammation and infection. That combined with the fact that there are many professionals with more experience with Gallium Scintigraphy makes them a very useful tool.
How much radiation am I getting from all these scans?Looking for more information about the various types of scans? There is a ton of it on the Internet. Just use your favourite search engine to search for "FDG PET", or "Gallium Scintigraphy" or "Computed Tomography". You'll find lots of information. One question that might occur to many patients is "Just how much radiation do I get from these various scans?" Of primary concern are X-rays, and CT's since they deliver radiation directly to your body. PET and Gallium scans inject radioactive substances into your body, but in only the most minute quantities. Nevertheless a PET scan delivers approximately the same amount of radiation to the body as a whole body CT scan.
It is a tough question to answer, but there is no doubt that a CT scan delivers dramatically more radiation to your body than any type of x-ray. A CT of the chest and abdomen can deliver the equivalent of 300 chest x-rays in radiation. While that sounds very frightening it is important to understand that this is still a small amount of radiation due to the very sophisticated equipment in use today. However if you are interested in reading a bit more about various radiation doses you get on a regular basis click the links below.
While not quite related to diagnostic imaging the following link looks at the risk of radiation from mobile phones which is still a concern to many people. Mobile Phone Radiation and Health Guide
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Computed Axial Tomography) is the most common and useful type of scan for
regular detection and follow up of NHL. CT's are still just X-ray images but
they produce a near 3D image of the interior of the body. They do this by having
the scanner spin around the body taking multiple pictures, or slices. A computer
combines these images into a single image that looks like a slice taken right
out of your body when looking down from the top of the head.