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Posts Tagged ‘x-ray’

 

medical-imaging

Doctors use diagnostic medical imaging to find out the possible causes of illness, injury or pain, to help provide an accurate diagnosis. These images include X rays, CAT scans, MRIs, and ultrasound.

X-rays were the very first imaging technique and are still the most commonly used today. X-rays use radiation which produces rays that pass through the body. When striking something dense like bone the image appears white and when going through something hollow like the lungs the image appears black. Muscle and fat appear as shades of gray. Sometime a dye can be introduced into the body before the x-ray, to make certain organs stand out.

X-rays used to be developed on a type of photographic film which needed to be developed and stored. Now the x-ray images can be instantly viewed on a computer screen, eliminating the need for the old film technique. This is a landmark feature because not only are the digital images immediately available, but they can be sent instantly to another source, such as a consulting physician.

X-rays are still excellent for evaluating bones, teeth, the chest (including the lungs and heart), and swallowed opaque items such as coins and most pieces of glass. The digestive tract can be visualized using a dye, such as barium.

Computerized Axial tomography ( CAT/CT ) scans use x-rays with computers to produce 360 degree cross sectional views of the body. These views allow the physician to see details of bony structures, chest, heart and lung problems, cancers, and many other internal organs. A typical exam may take 10-30 minutes.

A CAT scanner is much larger and more complex than an x-ray machine. It is a very expensive piece of equipment and therefore more costly to the patient than an x- ray. In spite of the increased cost, CAT scans can provide the physician with much more information and diagnostic ability than can most x-rays.

CAT scans use substantially more radiation than conventional x-rays and therefore should be used only when absolutely necessary. Don’t hesitate to ask the ordering provider if the scan is absolutely necessary.

Magnetic Resonance Imaging ( MRI ) combines a very powerful magnet along with a computer and radio waves ( no radiation exposure ) to provide detailed, accurate images of bones, internal organs, soft tissue, and other internal body parts. Patients must be carefully screened to insure that they have nothing metallic in or on the body such as rings, necklaces, pace makers, metal implants and some tattoos, because of the use of the magnet.

MRIs often take at least 30 minutes or more and, as with the CAT scan, can take cross sectional images of the body area being studied. The patient needs to lie completely still inside of a large tube, which may be very difficult for a person with claustrophobia. While inside the tube, the MRI machine makes a very loud knocking sound, usually necessitating the need for wearing ear plugs. The MRI is the most expensive of all the imaging techniques.

Ultrasound uses high frequency sound waves to produce images of structures within our bodies. Like MRIs, it uses no radiation and is very safe. A small hand held device is pressed against lubricated skin and moves it around to capture the image. This exam can take from 30 minutes to an hour. Unlike the other imaging techniques, this exam can also be used in a doctor’s office or emergency room making it a very useful diagnostic tool in many circumstances.

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With the arrival of summer, many of us will be traveling by airplane. Those of us who are older than 50 can remember going in and out of airports free of any type of security measures. Now, to board a plane, we have to nearly disrobe, get patted down and, most recently, pass through full-body scanners that take an image of our body.

About 500 full-body scanners are in use at airports throughout America, falling into one of two types: Half are millimeter-wave scanners, and half are backscatter x-ray scanners.

Millimeter-wave scanners use radio waves to create an image of the body and produce no ionizing radiation. Backscatter x-ray scanners use ionizing radiation, which is the type of radiation that can cause tissue damage and cancer.

So, are full-body scanners safe? Depends who you listen to.

There is not much concern about side effects from the millimeter-wave scanners. Regarding backscatter x-ray scanners, a study done by radiation experts at the University of California, San Francisco, School of Medicine concludes that they are safe. The study states it would take more than 50 full-body scans by the backscatter x-ray scanner to equal the radiation exposure of one dental x-ray; 1,000 scans to equal a chest x-ray; and 200,000 scans to equal a CAT scan.

The study also provides many statistics to show that the use of x-ray scanners would produce only a trivial increase in cancer, such as six more cases of cancer among 100 million people scanned.

Other investigators have calculated a higher, although still extremely low, risk of cancer from the x-ray scanner. There are many who would argue that this is a small risk and may be acceptable, given the possibility of stopping a terrorist.

I assume the statistics I quoted from the study are probably correct, but I have several questions:

**Are the machines working properly to give the correct amount of radiation?

**Is any risk of increased cancer, albeit extremely small, worth the risk?

**If we have the non-ionizing millimeter-wave scanner that appears to be safe, then why would the backscatter x-ray scanner be used at all?

Each of us needs to decide what to do when we go through airport security. As for myself, I wouldn’t think twice about going through the millimeter-wave scanner. But, although I think that the risk of harm from the backscatter x-ray scanner is probably very small, if I have the luxury of time before boarding my plane, I’ll choose to get a pat-down as opposed to the x-ray scan.

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There has been a lot of attention recently about the amount of radiation to which patients are exposed by medical x-rays. As with most medical procedures, x-rays are safe when used with care — especially because, in most cases, as little radiation as possible is used to obtain the needed results.

Why worry about radiation exposure? Radiation in sufficient doses can ultimately cause cancer. It is difficult to arrive at any accurate figure of the number of cancer cases due to x-ray exposure, but it is probably fairly low.

The recent discussion of radiation exposure deals with the newer generation of x-ray exams, especially CT (or CAT) scans. About 60 million scans are done yearly in the U.S. This computerized type of x-ray exam has revolutionized the ability of a physician to diagnose critical diseases and injuries, such as appendicitis, stroke, blood clots in the lungs, kidney stones, internal injuries from accidents, heart attacks and many more serious medical problems. However, the scans expose a patient to much higher doses of radiation than plain x-rays.

Technological advances can help in reducing radiation exposure. Newer scanners may use less radiation, and newer guidelines may allow doctors to use CT scans less often. Attitudes about scanning might need to change, as well. Doctors and patients need a heightened level of awareness about the amount of radiation to which one is exposed.

Another source of concern is the entire-body scan, which has been made popular through direct advertising to the public and can probably cause more harm than good.

In addition to medical diagnostic radiation, we are all exposed to natural environmental radiation from cosmic forces, such as the sun, and even rocks and minerals. You might live in an area with a high exposure to radon gas in your house, which can give you added exposure to radiation. There is also exposure — although very minimal — to man-made factors, such as nuclear weapons-testing fallout, industrial sources, luminous watch dials and smoke detectors.

The bottom line is that you should agree to have a radiation-based medical test when it can improve your health or save your life. Your doctor should discuss with you the benefits versus risks of any x-ray test that is ordered for you.

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