Ch. 2: Radiation Concepts

Matter

Has mass and occupies space

Energy

Is a force to do work

Radiation

Emitted energy is when matter is struck by radiant energy (taking an x-ray = taking an exposure)

Law of conservation of matter and energy

The sum of matter and the sum of energy is constant

E=mc²

Substances

• Simple

• Complex

• Atom

• Molecule

Simple substance

Element/pure subtance (cannot be broken down)

Complex Substance

Compound, 2+ elements united (different elements)(can be visible)

• EX: H2O

Atom

Includes protons, neutons, elements

Molecule substance

2+ atoms united (can be some or different)

Atomuc Theory: Historical Overview (include)

• Ancient Greeks

• Dalton (early 1800s)

• Rutherford (1911)

• Bohr (1913)

• Schrodinger

Ancient Greeks (Atomic theory: historical overview)

Air, water, earth, fire

Dalton (early 1800s)(Atomic theory: historical overview)

• Separted elements based on mass

• Lead to mendeleev’s development of periodic table of elements

Rutherford (1911)(Atomic theory: historical overview)

Dense, positive nucleus surrounded by cloud of negative electrons

Bohr (1913)(Atomic theory: historical overview)

Miniature solar system (expanded daltons work)

Schrodinger (Atomic theory: historical overview)

• The foundation of modern physics

• Ouatum physics or wave mechanics

Quantum Physics

• Study of matter/energy at most fundamental level (Subatomic particles)

• Protons/neutrons made up of quarks

• M theory (string theory)

M Theory (String Theory)

• Links quantum physics and relativity

• How matter responds to stimuli and environmental factors on quantim levl

• Five string theories

Basic atomic particles

• Proton (+ charge)

• Neutron (no charge)

• Electron (- charge)

Ionization

• X-ray photons can interact with an atom, resulting in the ejection of an electron

• Change charge between atoms

• Formed by energy/interacting with matter

DOES NOT change element

Orbital Electrons

Defines location where an electron might be at any given time in an atom. Shells include:

• K(1),L(2),M(3),N(4),O(5),P(6),Q(7)

Electron Binding energy (Eb)

Energy needed to eject from atom

• Related to closeness of electron to nucleus

• Eb increases as zX increases

Types of energy

• Mechanical energy

  • Potential

  • Kinetic

• Chemical Energy

• Heat Energy (Thermal energy)

• Nuclear energy

• Electrical energy

• Electromagnetic (EM) energy

Mechanical Energy (includes)

• Potential energy

• Kinetic

Heat Energy (thermal energy)

• Movement of molecules

Nuclear Energy

Obtained by breaking bonds between particles (nucleons) within nucleus

Electrical Energy

Movement of electrons in conductor

Electromagnetic (EM) energy

• Both electic + magnetic fields traveling through space

• Produced by acceleration of charged particles

• Travel in medium or vacuum

• Excitation/ionization

• Energies arranged in spectrum (Wavelength/frquency)

• X-ray only type photon EM energy

Characteristics (EM Radiation)

• Wavelength

• Energy

• Frequency

Particle Theory

• High frequency, high energy EM Radiation

• Interacts like particles when in contact with matter

E=hv (E: photon energy)(v: photon energy)(h: planks constant)

Discovery of first X-ray

Wilhelm Condrad Rontgen (1895)

Wilhelm Conrad Rontgen

• First Nobel Prize winner (physics)

• Occurred while studying electrons travelling through gas tube

• First: X-ray image was the left hand (with a ring)

• Barium platino cyanide as a fluorescent

X-Ray Properties

• Penetrating and invisible form of EM radiation

• Electrically neutral

• Polyenergetic or heterogeneous energies

• Release heat when passing through matter

• Travel in straight lines

• Travel at the speed of light in a vacuum

• Can ionize matter

• Cause fluorecence (emission of light) of certain crystals

• Cannot be focused by the lens

• Affect photographic film

• Produce chemical and biological changes in matter through ionization and excitation

• Produce secondary and scatter radiation