Radiography - Chapter 1

Atomic Theory: A scientific theory that matter is composed of discrete units called atoms.
Electromagnetic Spectrum: The range of all types of electromagnetic radiation, arranged by frequency and wavelength.
Energy: The capacity to do work or to produce change; in electromagnetic waves, it relates to frequency and wavelength.
Thermal Energy: Energy that comes from the temperature of matter. It reflects the kinetic energy of particles within an object.
Frequency (f): The number of occurrences of a repeating event per unit of time, measured in Hertz (Hz).
Wavelength (λ): The distance between successive crests of a wave, typically measured in meters.

Wilhelm Conrad Roentgen (1895): Discovered x-rays while experimenting with Crookes tubes, glass vacuum chambers containing an anode (positive electrode) and cathode (negative electrode).
- Observation: Upon passing an electrical current between the electrodes, Roentgen noticed a glow, now known to result from electrons interacting with residual gas in the tube.
- Understanding of Cathode Rays: Initially attributed to cathode rays, as they appeared emitted from the negative electrode. These early studies contributed to a better understanding of these mysterious rays, which were eventually characterized as x-rays due to their unknown nature.
- Source Used: NationalMagLab.org.

Highly penetrating invisible rays that form electromagnetic radiation.
Electrically neutral.
Produce a wide variety of energies and wavelengths.
Release a small amount of heat as they pass through matter.
Travel in straight lines.
Travel at the speed of light in a vacuum.
Ionize matter.
Cause fluorescence of specific crystals.
Not focused by a lens.
Affect photographic film.
Induce chemical and biological changes in matter due to ionization and excitation.
Produce secondary and scatter radiation.

Electromagnetic Spectrum: This spectrum encompasses all types of electromagnetic (EM) radiation, arranged from increasing frequency and decreasing wavelength. Higher frequency means greater energy.
Types of Radiation:
- Ionizing Radiation: Carries enough energy to ionize atoms in its path.
- Non-Ionizing Radiation: Does not have enough energy to ionize atoms.
Examples of Radiation:
- Radio Waves: Longest wavelength, lowest frequency.
- Infrared Waves: Heat radiation.
- Visible Light: The spectrum of light visible to the human eye, denoted by ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet).
- Ultraviolet (UV) Light: Can penetrate living cells, producing Vitamin D; blocked by clothing.
- X-Rays: Can penetrate tissues and cause damage; blocked by dense materials like bone.
- Gamma Rays: Highest energy and shortest wavelengths; extreme penetration power, often requiring 3-4 feet of concrete to stop them.

X-rays and Gamma Rays: Both classified as ionizing radiation.
- X-rays: Used in diagnostic imaging within veterinary practices.
- Gamma Rays: Utilized in nuclear medicine applications like scintigraphy.
Energy Units:
- Measured in electron volts (eV).
Frequency: Measured in Hertz (Hz), which denotes cycles per second.
Wavelength (λ): Measured in meters, specifically ranges from 0.03 to 3.0 nanometers for x-rays.
- Composed of frequency and amplitude, where:
- Amplitude: Height of the wave.
- Frequency: Distance between wave crests.

Wavelength and Frequency Relationship:
- Long Wavelength: Corresponds to low frequency and limited penetrating power (e.g., radio waves).
- Short Wavelength: Corresponds to high frequency and increased penetrating power (e.g., gamma rays).
Wave-Particle Duality of X-Rays:
- Photons: The smallest quantity of any type of electromagnetic radiation, interacting with matter as though they are particles.
- Energy-Frequency Relationship:
- Energy and frequency are directly proportional; as energy increases, frequency also increases.

Energy can be conceptualized as existing both in wave forms as part of the electromagnetic spectrum and as particles (photons) that have specific energies depending on their frequency.