Radiation 101
We’re exposed all the time to natural radioactive materials just by living on earth. Here’s
how to put scanning tests into perspective.
An X-ray penetrates the body but not the bones. One chest X-ray
gives off the same amount of radiation as a person would receive
naturally in ten days.
X-rays
These are 3-D X-rays, taken multiple times to show several layers
of bone and muscle. The amount of radiation varies depending
on the area scanned. A CT of the abdomen or spine, for example, equals three
years of daily radiation. But a head scan equals eight months’ worth.
CT scans
Ultrasound
This test uses acoustic radiation, or sound waves, to show an
internal body part and does not pose a radiation risk.
Magnetic resonance imaging does not use radiation. Instead, it em-
ploys magnets and a radio-frequency pulse that tracks the hydrogen
atoms in the body to create an image. The downside: An MRI is very expensive
and is not used for routine screenings.
MRI
Bone-density scan
This test uses X-ray technology but at a very low dose—
one scan is equivalent to a day of natural radiation.
The problems are leading many
doctors to question which tests are
beneficial and under what circumstances. And they’re setting off some
highly charged debates in the medical
community and beyond.
“We get a lot of what we call ‘
inci-dentalomas,’ abnormalities we see on
the C T scan and don’t know what they
are,” says Leipzig. “Then we’re left
wondering if it’s something to be concerned about and whether the patient
wants to go through what it takes to
chase this down.” In her own experience, she says, the chase is often not
worth the stress, cost, and pain. It’s
one reason many medical experts
have gone out of their way to strongly
recommend against the full-body
CT scan that has been so heavily marketed to consumers in recent years.
So which tests are essential? Routine screenings recommended by the
USPSTF (which is supported by the
Department of Health and Human
“RADIATION 101” SOURCE: RADIOLOGICAL SOCIETY OF NORTH AMERICA
