How do x-rays work?

Discovery of the x-ray
X-rays were discovered by a german physicist named Wilhelm Roentgen in 1895.  He was experimenting one day in his laboratory when he stumbled upon something so amazing he was unsure if it was actually real.  Although many books state that Wilhelm was the first, A.W. Goodspeed was actually the first person to make this incredible discovery, on February 22, 1890.  With no information or even proof that he had discovered what he had, Goodspeed did not take credit but instead renamed his discovery an accident.
The process of what Wilhelm discovered in his dark laboratory that day is as follows-
He enclosed a glass tube inside of a black paper box.  The glass tube had wiring that was running inside of it, much like what a light bulb has.  This allowed for electrical currents to build up inside of the glass tube.  The tube was connected with an induation coil apparatus which let an electric current travel into the tube.  When this occurred a faint green colored light appeared across the room.  He was not quite sure if his eyes were fooling him or not, so he decided to make sure of the new found light that he had discovered.  Lighting a match, he discovered a small screen across the room which was coated with a chemical.  He blew out his match and once again, sent the current.  The exact same light appeared.  Wilhelm was incredibly thrilled!  As days and weeks passed, he also found these so-called rays, naked to the eye, could penetrate through objects like wood and metal.  One day, his hand came in contact with the tube, and to his suprise he saw shadows of his hand and fingers with darker shadows representing the bones.  When he moved his hand, the shadow on the screen moved too.  This shadow became known as the first x-ray picture.


How does it work?
X-rays were found to be able to penetrate through materials of light atoms like flesh.  The heavier atoms like metal absorb them.  A beam of high energy electrons crashes into a metal target and x-rays are produced.  A filter near the x-ray source blocks the low energy rays so only the high energy rays pass through a patient toward a sheet of film.  Along with the sheet of film, a second sheet of film prevents the scattered x-rays from fogging the picture.  Calcium in bones is considered a type of metal and when photographic film is placed on the body, this allows the technician to take the picture and an x-ray is developed to solve or analyze the problem.  These rays were found to be harmful to the skin and soon new ways of medical imagers were developed.


What do we use them for?

Lesson Plans and Fun Ideas

Lesson Plans from Everyday Discoveries by:Sharon MacDonald
page 67

The x-ray box

You need:
-cardboard box, 12"x16"x21" (30cmx40cmx53cm)
-sharp cutting tool
-white tempera paint
-several paint brushes
-2 strips of wide fabric or ribbon, 12" (30cm) long
-skeleton or picture of a skeleton

-Cut out the top and bottom of the box
-Staple the strips of fabric across the top
-When the children arrive, have them help you make an "x-ray machine."  First, ask them to examine the skeleton or skeleton picture and count the ribs.
-Next, ask them to decide which part of the skeleton would show if one of the children hung the box from his shoulders
-Encourage them to paint the box front like the skeleton they imagine they would see
-The children can slip into the box and pretend to have an x-ray made

Questions you might ask:
-How is this x-ray machine different from a real one?
-Can you think of another way to make a picture of the inside of a body?

More challenging for older children:
Divide the class into groups of four or five.  Give each group a box, skeleton picture and paints to draw skeletons.  Compare the group's results after they have made their x-ray boxes.

Modifications for younger children:
Give each child a smock.  Children pain their skeletons on the smock.

Science and Math principle:
Teaches children about models by making a representation of a bone.

page 68

A Puzzling x-ray

You need:
-large x-ray film
-black permanent marker

-Before the children arrive, cover any name on the x-ray with black permanent marker and cut the film into three, five, seven or more pieces (depending on how hard you want the puzzle to be)
-Place the pieces on a tray and place the tray for the children to examine and ask questions about (not only of you, but of their classmates, from whom they will learn a great deal)
-Have the children assemble the puzzle

Questions you might ask:
-How are the x-ray pictures of bones like the bones in your body?
-Why do our bodies have bones?

More challenging for older children:
Cut the x-ray film into twenty to thirty pieces.  Obtain a second x-ray film of the same body part.  The children compare the second film to the first, finding similarities and differences.

Modifications for younger children:
After you cut the film into puzzle pieces, trace the outline of each piece of the puzzle, in assembled form, on a large sheet of white paper.  This gives younger children a base (and a reference) upon which to work the puzzle.

Science and Math principle:
Teaches children about the properties of bones.

Page Created by:
Katie Juhl, Elementary Education Major at Concordia College in Moorhead, MN
Special Thanks to:Sharon MacDonald