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What You Need to Know About X-Rays

Last December we received a letter from a mother who had just read an article which warned that young girls undergoing x-ray should wear protective breast shields. She wanted to know where she could buy these shields for her daughter. The question made us realize that there are many misunderstandings about the x-ray process. To broaden our knowledge, we interviewed Dr. Joseph P. Dutkowsky, Assistant Professor of Orthopedic Surgery and Pediatrics at the University of Virginia.

Q: Dr. Dutkowsky, let's begin at the beginning. Who first discovered x-rays and why were they given that name?
A: The German physicist Wilhelm K. Roentgen discovered them way back in 1895. During one of his experiments, he noticed that radiation not only penetrated through the skin so he could see deeper structures like bone tissues, but it also produced phosphorescence or light. Because he didn't really know what these mysterious rays were, he named them "X" rays. Today, we know that x- radiation is all around us-in the atmosphere, in the ground beneath our feet, and even in our own bodies. We're all radioactive, you know. And it has nothing to do with what we eat or drink-it's just the way the good Lord put us together.

Q: Since our readers are interested in scoliosis x-rays, would you tell us how much radiation is produced by a scoliosis x-ray compared with other sources of radiation.
A: To answer that question, let's first talk about how radiation is measured. The standard unit of radiation is called a "rad." For measurement purposes, we usually divide a rad into thousandths, which we call "millirads." In other words, 1/l000th of a rad equals one millirad. Now, to put that into perspective, consider a few figures:

  • If you stayed outdoors all year round in New York City, you'd get 90 millirads of radiation.
  • If you stayed in a brick building 24 hours a day for a year in New York City, you'd get 140 millirads.
  • If you live outside the fence of a nuclear power plant, the U.S. government would allow you to get 125 millirads per quarter, or 500 millirads per year.
  • If you have a dental x-ray, you'd get 1,000 millirads.
Q: That's fascinating, but what about the radiation from a scoliosis x-ray?
A: If a young girl has a scoliosis x-ray exam, comprised of one PA (posterior- anterior view, or back to front) x-ray plus one lateral (side view) x-ray, and assuming preventive measures have been taken to protect her breasts, her breast tissue would receive a total of 10 millirads.

Q: Clearly, the amount of radiation from one scoliosis x-ray isn't very much. But as everyone knows, x-radiation can alter tissue and destroy it. So what preventive measures do doctors use to avoid these problems?
A: The first preventive measure is to avoid x-radiation whenever possible. How do we do that? Well, during the course of treatment, a doctor may use a scoliometer or other non-imaging method to monitor the patient's curve. Unfortunately, though, devices like the Scoliometer cannot give us exact information about a curvature; only an x-ray can provide us with an extremely accurate picture of a curvature. And in certain instances, when the patient is seen for the first time and shows signs of scoliosis, or later on if his or her curve has progressed, a doctor may need to x- ray the patient in order to determine the precise nature and degree of the curve.

Q: In those instances when an x-ray cannot be avoided, what do doctors do to lessen a patient's exposure to radiation?
A: First, let me tell you what doctors have done in the past several years. To begin with, they have increased and standardized the distance of the patient from the x-ray machine. Patients now stand six feet from the machine, which automatically cuts down x-radiation exposure. Secondly, they've reversed the position of the patient who must have standing x-rays. Instead of having patients face the machine, which allowed x-radiation to enter sensitive breast tissue first, we now turn them around so their backs face the machine. By doing this, the spine and ribs absorb much of the radiation before it reaches the breast.

Q: What else can be done?
A: Doctors use a variety of lead shields that block roughly 99 percent of the radiation generated via an x-ray machine. For young girls, whose breast tissue is the most sensitive to radiation, we use breast shields. Made of lead and covered with heavy cloth, the shield looks a lot like an apron and covers the breast area during x-radiation. When necessary, we also use lead shields that protect the female's pelvic region where reproductive organs are located. For young boys, we use lead shields for the gonadal area. In addition, all modern x-ray machines have lead shields built right into them so that a narrow x-ray beam is produced minimizing exposure.

Q: Since today's x-ray machines already contain lead shields for protection against radiation, is it necessary to use the breast and/or gonadal shields as well?
A: By using the lead aprons for breasts and/or gonads, you're adding another measure of safety. At most scoliosis clinics, using these aprons is a standard procedure.

Q: We've heard about something called "rare earth screens." What are they and what do they do?
A: I'm glad you brought that up, cause that's a way that we lessen x-radiation exposure. Placed on each side an x-ray film, rare earth screens produce more light; you can use fewer x-rays to get the same picture. For that reason, all scoliosis clinics today should use rare earth screens.

Q: Even with all the preventive measures now being used, particularly those that protect sensitive breast tissue, what is the risk of breast cancer in young girls who've had scoliosis x-ray exams?
A: We've made a lot of progress in that area, too. In 1979, Dr. Clyde Nash did a study indicating that the typical female adolescent with scoliosis would undergo 22 x-ray exams during the course of treatment. Due to those x-rays, he estimated the risk of breast cancer would increase 110 percent . In my most recent study, which takes into account the many preventive measures which I've already mentioned, we've found that the risk has been lowered to .22 percent, or roughly a fourth of one percent. In other words, assuming that 22 radiographic examinations are performed over the course of scoliosis treatment-a greater number of x-rays than one would routinely receive today-our findings reveal that the increased relative risk of breast cancer is roughly two breast cancers per million women examined per year beginning at age 35. That's an extremely small number considering that the risk of a woman getting breast cancer in her lifetime in the United States is one out of eleven.

Q: Even though your figures are relatively reassuring, we all want to try to protect ourselves from radiation as much as possible. Any other recommendations?
A: When patients have to have an x- ray, they should ask questions about the equipment and procedures. Remember, patients have the right to demand any or all of the preventive measures I've mentioned. I believe that the patient's body is ultimately his or her responsibility. The more you know about the care you're getting, the more informed and comfortable you'll be, and that helps doctors do their jobs. Most if not all scoliosis clinics will be using the procedures I've mentioned, but it never hurts to ask questions to reassure yourself. You'll feel better about what's being done.

Q: What about the future? Are other devices in the works?
A: The best "replacement" technology will probably be magnetic resonance imaging or MRI; it doesn't use any radiation at all to get a picture of the inside of the human body. Simply explained, it's a magnetic device that's used with a computer to provide exquisitely detailed images. If scientists can figure out how to make it less expensive, more available, and faster at developing images, I suspect it eventually will be the ultimate tool.


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