Dental Radiography: Nature, Discovery, and Uses

• The Course Learning Outcome includes explaining the nature of radiation and its effects on matter.
• The Course Learning Outcome includes describing briefly the discovery of radiation and listing the characteristics of radiation.
• The Course Learning Outcome includes a description of the basic structure of atoms and the principles of ionization.
• The Course Learning Outcome involves describing the interactions of radiation with matter.

Uses of Dental Radiography

• Dental radiographs aid in detecting lesions, confirming or classifying suspected diseases.
• Radiographs are used to localize lesions or foreign objects, provide information during dental procedures.
• Radiographs help to evaluate growth and development, illustrate changes secondary to caries, periodontal disease, or trauma.
• Radiographs are necessary for documenting the current condition of a patient.

Radiography Basics

• An X-ray is a beam of energy capable of penetrating substances and recording image shadows on photographic film.
• A radiograph provides a two-dimensional representation of a three-dimensional object.
• An image receptor is a recording medium, such as x-ray film, phosphor plate, or digital sensor.
• Dental imaging involves creating digital prints or film representations of anatomic structures for diagnosis.
• Disease detection is a primary use for dental images.
• Wilhelm Conrad Roentgen discovered the x-ray in 1895.
• Digital imaging is a significant advancement in dentistry, allowing instant review and transmission of images, reducing patient exposure, and improving diagnostic potential.

Fundamental Concepts

• Key areas include atomic and molecular structure, ionization, radiation, radioactivity, and ionizing radiation.
• The world is composed of matter, which has mass, and energy, like light, which has no mass.
• The fundamental unit of matter is the atom.
• All matter consists of atoms.
• Atoms contain positively charged protons, neutral neutrons, and negatively charged electrons.
• A stable atom has a central nucleus with a positive charge, where the number of electrons equals the number of protons maintaining electrical neutrality.
• Most of an atom's weight is from protons and neutrons, while electrons have very little weight.
• An atom has a central nucleus with orbiting electrons and the identity is determined by the nucleus composition and electron arrangement.
• The nucleus is composed of protons, which have a positive electrical charge, and neutrons, which have no electrical charge.
• The atom's mass number or atomic weight is the number of protons and neutrons in the nucleus.
• The atomic number is determined by the number of protons inside the nucleus, which equals the number of electrons outside the nucleus.
• Atoms are arranged on the periodic table in increasing order of their atomic number.
• Electrons are tiny, negatively charged particles with very little mass, about 1/1800 as much as a proton or neutron.
• Electrons travel around the nucleus in well-defined paths known as orbits or shells.
• The shell nearest the nucleus has the highest energy level.
• An atom contains a maximum of seven shells, designated K, L, M, N, O, P, and Q.
• Electrons are held in their orbits by the electrostatic force between the positive nucleus and negative electrons.
• Binding energy is the force maintaining electrons in their orbits.
• The K shell has the strongest binding energy and the binding energy is determined by the distance between the nucleus and the orbiting electron.
• Atoms combine with each other to form molecules.
• Molecules are formed by transferring or sharing electrons in the outermost shells of atoms and the energy required to remove an electron from its orbital shell must exceed the binding energy of that electron.
• It is easier to dislodge an M shell electron versus a K shell electron due to its high binding energy.
• An ion is an electrically unbalanced atom that has gained or lost an electron.
• Usually, atoms have an equal number of protons and electrons and are neutral.
• Gaining an electron results in a negative charge, and losing an electron causes a positive charge.
• If an atom has 4 protons and 5 electrons, the charge of the atom is -1.

Ionization

• It is the production of ions by converting atoms into ions.
• When an electron is removed from an atom during ionization, an ion pair results.
• The ion pair includes the atom becoming a positive ion, and the ejected electron becoming a negative ion looking to join another atom or be shared between atoms in a molecule.
• The formed ion pair-positive and negative- reacts with each other until neutral atoms are formed.
• Radiation involves the emission and propagation of energy through space or a substance, either in waves or particles.
• X-radiation is used in dentistry.
• Ionizing radiation is one type, while non-ionizing radiation is another.

Ionizing Radiation

• It is capable of producing ions by removing or adding an electron to an atom.
• Particulate radiation such as alpha and beta particles at high speed can cause damage.
• Another type is electromagnetic radiation.

Particulate Radiation

• It involves tiny particles with mass that travel at high speeds in straight lines.
• Examples are electrons, neutrons, and protons that can lose control at high speed.
• Electromagnetic radiation is the propagation of wavelike energy without mass through space or matter, with oscillating electric and magnetic fields at right angles to each other.
• Electromagnetic radiation can be human-made or occur naturally.

Electromagnetic Spectrum

• Electromagnetic radiation is arranged in the electromagnetic spectrum based on energy.
• Cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light, radar waves, microwaves, and radio waves are examples of electromagnetic radiation.
• Electromagnetic radiation have similar characteristics and can be either ionizing or non-ionizing.
• High-energy radiations can cause ionization, such as cosmic rays, gamma rays, and x-rays
• Electromagnetic radiation is both a particle and a wave, similar to a person on a waterslide.
• Particle Concept terms electromagnetic radiation as discrete bundles of energy called photons, which have no mass, no charge, travel at the speed of light, and move in a straight line.
• Wave Concept characterizes electromagnetic radiations as waves with velocity, wavelength, and frequency.
• Velocity is the speed of the wave.
• Wavelength is the distance between the crests of two waves.
• Frequency is the number of wavelengths passing a point in a given time.
• Low energy radiation has a low frequency and a long wavelength.
• High energy radiation has a high frequency and a short wavelength.

X-Radiation Characteristics

• X-rays are high-energy, ionizing electromagnetic radiation.
• X-rays consist of weightless bundles of energy without an electrical charge that travel in waves at a specific frequency at the speed of light.
• X-ray photons interact with the materials they penetrate and cause ionization.