X-Rays    Sarah Fiorelli, Anne Adams, Carissa

Ferarro, Caisang Huang, and Yingying Han

X-Rays

Prehistory of X-Rays• William Crookes

o Created an electrical discharge tube from which the air could be almost completely removed

o Streams of electrons (cathode rays) were discovered in the tube

o Now known as cathode ray tubes or Crookes tubes

o Played a role in scientific discoveries, notably the discovery of the electron's negative charge

Prehistory of X-Rays

• Wilhelm Conrad Röntgeno Worked with Crookes tubes

o November 8, 1895: Röntgen noticed a screen of barium platinocyanide was glowing in his lab, near where he had been testing cathode rays

o Tube was a foot away from the screen, and also was covered with black carbon paper

o Röntgen spent six weeks determining the nature of the screen's fluorescence

Discovery of X-Rays

• After testing, Röntgen determined he had discovered a new form of electromagnetic radiation, between gamma rays and ultraviolet rays

• Named "x-rays" (for their enigmatic nature), Röntgen found they could penetrate solid substances (like the black carbon paper) that many other light rays could not

• When he placed his hand between the tube and the screen, he saw the outline of his bones projected onto the screen

The hand (with wedding ring) of Mrs. Röntgen

Discovery of X-Rays (con't)

• Röntgen brought his wife into the lab, and produced the first picture of an x-ray

• Röntgen realized his discovery would transform medical practices and published his findings

• x-rays were used by doctors within one year, and Röntgen won the Nobel Prize in physics in 1901. 

Before the Discovery of X-rays 

•  Before the discovery of X-rays, scientist and doctors had no certain way of examining the bones, tumors, or the location of bullets within the human body

• In order to analyze the body, scientist and doctors would take a number of steps to diagnose their patients.

• These approaches were to:o  probe and examine the body 

Before the Discovery of X-rays  (con't)

•  • This process caused doctors to develop risky, and

sometimes dangerous, methods in order to examine wounds and other ailments

• Even through this process and elaborate methods doctors still were many times unable to correctly analyze the body

• Without the discovery of x-rays, doctors were basically shooting in the dark.  

After the discovery of X-rays• Since the discovery of X-rays, doctors are able to more

safely and successfully analyze the human body

• Within the medical world today, X-rays are used for many different uses. Some examples of these uses include:o the detection of cancero examining the condition of an internal organo determining if a bone is broken o determining the location of a bullet 

After the discovery of X-rays (con't)

• Now with the use of X-rays, doctors no longer have to guess when diagnosing a patient. 

• We can now use X-rays to not only diagnose individuals, but to intervene earlier and prevent diseases, such as cancer, from spreading or reaching a fatal stage

• In addition to medical advantages, the discovery of x-rays sparked a chain of discoveries within physics and medicine

The Dangers of X-rays

• When X-rays were first discovered, scientists and doctors were unaware of the harm that can be caused by these rays

• Before the dangers of X-rays were known, scientists and doctors and their patients were sometimes exposed to X-rays for long periods of time. When this occurred, these individuals became very sick. This sickness is known as radiation sickness. 

• X-rays are dangerous due to a form of ionizing radiation. X-rays are a form of light. When normal light interacts with atoms, the atoms stay intact and remain completely unharmed. However, when X-rays interact with atoms, they cause the atoms to form an ion. This change occurs when the X-rays hit the atom, causing electrons to be knocked off from the atom. This creates an ion, which is an electrically charged atom. Free electrons then collide with other atoms, creating more ions. 

X-Ray Machine Today

• Made up of two components of an electrode pair         1. Anode: positively charged disk made of tungsten         2. Cathode: Heated filament • Electrode pair sits inside a glass vacum tube

• Current is passed through the macchine which heats up the cathode which causes the electrons to shoot off the filament 

• Then the anode draws the electrons across the tube

• Due to the high voltage difference between the cathode and anode it causes the electrons to fly through the tube with a great deal of force 

•  Speeding electrons collide with anode and knocks loose an electron in one of the atoms lower orbits & a higher orbital electron fills the empty position 

•  The empty position releases energy as a photon 

X Ray Macchine Today (con't)• The now free electron is attracted to the tungsten atom nucleus 

• As the electron speeds past, the nucleus' course is then altered causing the electron to lose energy releasing an X-ray photon 

• A lot of heat is generated due to the high impact collision of the X-ray production, and a motor rotates the anode to prevent melting and overheating 

• Entire machine is surrounded by a thick lead shield to prevent X-rays from escaping in all directions, but has a small window that allows some of the rays to escape through a narrow beam 

• Narrow beam passes through a series of filters on its way to the patient

• On the other side of the patient there is a camera that records the pattern of Xray light which passes through the patient 

• Results come in the form of negatives o  areas exposed to more light = darker on the negatives o areas exposed to less light = lighter on the negatives 

Broken FInger Bone 

X- Ray Negatives 

Broken Leg 

Teeth: lighter spots indicate cavities 

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