Why is lymphangiography important in the diagnosis of cancer?

Lymphangiography is important to cancer diagnosis because one of the ways that cancer spreads is through the lymph nodes. Lymphangiography can be useful in the diagnosis and staging of persons with Hodgkin's disease and lymphomas and sometimes for other cancers. It is a procedure which is done in an outpatient setting or in a hospital. A blue dye is injected into the small lymph vessel after a cut is made in the big toe. The lymph system in the abdomen can then be looked at by means of x-rays. Since the lymph glands are very small, it usually takes 2 to 3 hours for the dye to reach the lymph nodes. Lymphangiography is used to localize and determine the extent of the tumors. The surgeon can use it as a guide to finding specific lymph nodes and determining the size of the tumor. The radiotherapist uses it to evaluate how a person is responding to therapy. Since the dye stays in the system for some 3 to 4 months, progress usually can be followed through x-rays without repeating the procedure.

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Do some of the parts of the body absorb more x-ray beams than others? 

If you put a part of the human body in front of a beam of x-rays, some of the rays will pass through, while others will be absorbed and scattered inside the body. Bone, for example, which is more dense, will absorb x-rays more readily than surrounding tissues. It is the shadows of these denser parts of the body which show up on the developed film or screen.

What kinds of contrast media are used for x-rays? 

X-rays are absorbed by dense substances such as barium or iodine. These contrast media can be swallowed, injected into the bloodstream, or inserted with a plastic tube or catheter. Sometimes dye and air are both used in contrast films. For example, often both barium and air are used for gastrointestinal examinations.

What kind of physician should read diagnostic x-rays? 

Diagnostic x-rays should be interpreted by doctors who are board certified (or board eligible) radiologists.

What kind of background does a radiologist have? 

A board certified radiologist (certification is by the American Board of Radiology) must be a graduate of an approved medical school; must have four years of postgraduate training in the department of radiology, including training in pathology, nuclear radiology, and therapeutic radiology; and must have successfully completed written and oral examinations administered by the board.

What is the difference between a diagnostic radiologist and a therapeutic radiologist? 

A diagnostic radiologist administers and interprets x-rays used in diagnosing illness. A therapeutic radiologist (also sometimes called a radiation therapist, a radiotherapist, or a radiation oncologist) specializes in treating cancer with radiotherapy. The American Board of Radiology gives separate certification to these two specialties.

How do I know where to go for my diagnostic x-rays? 

This is a subject you should discuss with your physician. Ask questions. If you can, have your x-rays done in the outpatient department of a medical school or major hospital or by a private board certified radiologist.

What questions should I ask before I have x-rays? 

You should ask the following questions:

• Are the x-rays clearly necessary for diagnosis?

• Are there any x-rays which I have had taken recently which might be used instead of taking new ones?

• What is the approximate dose of x-ray?

• What do you think you will find out from the x-rays?

• What dosage is the particular machine giving?

• When was the machine last inspected?

• What kind of shielding will be used during the procedure?

Is there really a difference between the machines used in one office and those in another? 

Yes, there is definitely a difference. You should know that both the quality of the x-ray equipment and the quality of the technician or doctor doing the x-ray make a difference in whether or not you receive a low or high dose of radiation. The expertise of the operator also makes a difference in how good the x-ray will be. Another variable is in who reads the x-ray after it is taken.

What kind of training do x-ray technicians have to have? 

There are some states which legally require that radiology technicians be trained and certified. The 1970 X-ray Exposure Study conducted by the Public Health Service shows that those x-rays supervised by radiologists in private offices involved less exposure than those supervised by nonradiologists in private offices. However, many states have been working with the FDA's Bureau of Radiological Health on radiation-control regulations and on training programs for personnel.

Are the machines inspected regularly? 

There are presently no U.S. government inspection requirements. Although some states do have requirements, in many states the equipment is not inspected every year. Some machines, particularly those in doctors' offices, go uninspected for long periods of time. There should be a certificate posted near the machine. Look at it to see when the last inspection was performed. If it was more than a few years ago, go elsewhere.

When should x-rays be considered a necessity? 

As noted earlier, x-rays are an important part of the diagnostic workup. When properly taken and read, they are one of the doctor's most valuable tools. However, the benefits of the x-ray must be weighed against the risks. A qualified professional is a better judge of when x-rays are needed than you are. You, however, need to know the right questions to ask so that you can assure yourself you are in the hands of a skilled and competent practitioner.

What is the major risk of diagnostic x-rays? 

The amount of radiation which x-rays deliver to your body is the biggest risk. It is believed that the risks of x-ray dosage are linear that is, the more dosage a person receives during a lifetime, the greater his or her chance of developing cancer or another abnormality.

Who can tell me what the approximate dosage should be for the various tests? 

Your doctor should be able to give you approximate dosages so that you can ask the technician where you are having the test done what dosage his machine is giving. For example, a standard chest x-ray involves between 5 and 10 millirem (.005-010 rem or rad); a mammogram should be under 1 rad for both pictures of each breast.

Do the x-rays belong to me? 

There is quite a bit of controversy over this issue. However, you have a right to ask that the x-rays taken in one place be sent to another doctor or hospital of your choice. Some doctors and hospitals will give them to you directly; others will insist on mailing them to the other physician or hospital. It might be a good idea to explain that you are concerned about x-ray overexposure.