文档介绍：Lecture 1: Overview; History of Radiation
Radiation can be defined as the propagation of energy through matter or
space. It can be in the form of ic waves or energetic
particles.
Source: Lawrence Berkeley Laboratories, “MicroWorlds: ic Spectrum.”[cited 26 March 2003.]
roWorlds/ALSTool/EMSpec/
Ionizing radiation has the ability to knock an electron from an atom, . to ionize.
• alpha particles
• beta particles
• neutrons
• gamma rays
• x-rays
Non-ionizing radiation does not have enough energy to ionize atoms in the
material it interacts with.
• microwaves
• visible light
• radio waves
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• TV waves
• Ultraviolet radiation (except for the very shortest
wavelengths)
Health effects depend on how radiation interacts with biological material at
the microscopic level.
Radiation delivers energy in “small packets”, not uniformly distributed
throughout the entire mass.
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Fig. in Hall, Eric J. Radiobiology for the Radiologist, 5 ed.
Philadephia PA: Lippincott Williams & Wilkins, 2000.
Sources of Radiation Exposure to the US Population
(from . NRC, Glossary: Exposure. [updated 21 July 2003, cited 26 March 2004]
ding-rm/basic-ref/glossary/
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1895: The Discovery of the X-ray
Radiation was discovered by Wilhelm Conrad Roentgen on November
8, 1895.
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Crookes/Hittorf Tube
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First “Roentgen Ray” image: December 22 1895
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One of the first images obtained by Rontgen
using x-rays, showing the bones of a hand.
1896: > 1000 papers published on X Rays.
Roentgen received the first Nobel Prize in physics in 1901
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What Happens in the Crookes/Hittorf Tube?
1. Phosphorescence/ Fluorescence: The glow from the tube
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Fluorescence: rapid (10-8 – 10-9 se