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Dental Radiology4
X-Ray Production and Image Formation
| Question | Answer |
|---|---|
| Matter | Anything that occupies space and has mass |
| Anything that occupies space and has mass | Matter |
| Atom, describe | *the smallest part of an element that still retains the properties of that element; *the most fundamental unit of matter |
| Atom consists of | a central nucleus that contains protons and neutrons, and orbiting electrons |
| atom combine with each other to form | molecules |
| The smallest part of an element that still retains the properties of that element; | Atom |
| The most fundamental unit of the matter | Atom |
| Electrons maintain position in their orbits (shells) by | Electrostatic force (attraction) between the positive nucleus and negative electrons; |
| How do electrons maintain their position in their orbits (shells) | By electrostatic force (attraction) between the positive nucleus and negative electrons; |
| What helps electrons to maintain their position in their orbits (shells)? | Electrostatic Force (attraction) between the positive nucleus and negative electrons; |
| Electrostatic Force aka | Binding energy, or binding force |
| Binding energy aka | Electrostatic Force, or binding force |
| Binding force aka | Electrostatic Force, or binding energy |
| How is binding energy determined? | By the distance between the nucleus and the orbiting electron |
| Binding energy is determined by... | the distance between the nucleus and the orbiting electron |
| What electron has the strongest binding force? | An electron positioned in an orbit closest to the nucleus (K shell) |
| An electron positioned in an orbit closest to the nucleus (K shell) has the | strongest binding force |
| Neutral atoms contain | the same number of protons and electrons |
| What atoms contain the same number of protons and electrons? | Neutral atoms |
| Atoms that gain or lose an electron become electrically unbalanced (they have either positive or negative charge), and are called | ions |
| Ions are ... | atoms that gain or lose an electron become electrically unbalanced (have either positive or negative charge) |
| Ionization is the | process of converting an atom to an ion |
| The process of converting an atom to an ion is called | Ionization |
| When an electron is removed from an atom, the result is... | the formation of an ion pair |
| Formation of an ion pair results when | an electron is removed from an atom |
| Ionizing Radiation, define | Radiation that produces ions when it reacts with matter; *Ions are produced by removing or adding an electron to an atom; |
| Ions are produced by | removing or adding an electron to an atom; |
| Radiation that produces ions when it reacts with matter is called | Ionizing radiation |
| Electromagnetic radiation, define | Type of ionizing radiation; Wave-like energy without mass that moves through space or matter; |
| Wave-like energy without mass that moves through space or matter is called | Electromagnetic Radiation |
| Examples of electromagnetic radiation | Cosmic Rays, gamma rays, x-rays, ultraviolet rays, visible light, microwaves, radio waves |
| What only type of energy radiation is capable of ionization? High energy or low energy? | Only high energy radiation (cosmic, gamma, x-rays) are capable of ionization |
| Examples of high-energy radiation | cosmic rays, gamma rays, x-rays |
| What is only high energy radiation capable of? | Only high energy radiation (gamma, x-rays, cosmic rays) are capable of ionization |
| Statement: Electromagnetic radiation has no mass or weight | True |
| Statement: Electromagnetic radiation has mass and weight | False |
| Statement: Electromagnetic radiation has an electrical charge | False |
| Statement: Electromagnetic Radiation has no electrical charge. | True. |
| Statement: Electromagnetic Radiation travels at the speed of light | True |
| Statement: Electromagnetic radiation travel a both a particle and a wave | True |
| Statement: Electromagnetic Radiation travel only as a particle | False. Travel both as a particle and as wave. |
| Statement: Electromagnetic Radiation travel only as a wave | False. Travel both as a particle and as wave |
| Statement: Electromagnetic Radiation propagate an electric field at right angles to path of travel | True |
| Statement: Electromagnetic radiations propagate a magnetic field at right angles to the electric field | True |
| Statement: Electromagnetic Radiations have different measurable energies. | True. Frequencies and Wavelength |
| Properties of Electromagnetic Radiations: | *no mass/weight *no electr charge *travel @speed oflight *travel as both particle &awave *propagate an electr field @right angles topath of travel *prpgte a magnetic field @right angles totheelectr field *have dffrnt measurable energies(frequenc/wavelengt |
| What moves through space as both a particle and a wave | Electromagnetic Radiation |
| Electromagnetic Radiation moves through space as both a particle and a wave: Particle concept describes electromagnetic radiation as bundles of energy called | photons |
| Electromagnetic Radiation moves through space as both a particle and a wave: wave concept describes electromagnetic radiation as | waves and focuses on wavelength and frequency |
| Electromagnetic Radiation and particle concept | Particle concept describes electromagnetic radiation as bundles of energy called photons |
| Electromagnetic radiation and wave concept | Wave concept describes electromagnetic radiation as waves and focuses on wavelength and frequency; |
| Wavelength, definition | The distance between the crest of one wave to the crest of next wave |
| The distance between the crest of one wave to the crest of next wave is | Wavelength |
| Wave frequency, definition | Number of wavelengths that pass a given point in a certain amount of time |
| Number of wavelengths that pass a given point in a certain amount of time | Wave frequency |
| Short wavelength and more frequency is characteristic of what radiation? | High frequency electromagnetic radiation |
| What is the speed of light | 186,000 miles/second |
| X-Radiation is | High-energy, ionizing, electromagnetic radiation |
| Characteristics of X-Rays: | *Weightless bundles of energy (photons); *No electrical charge; *Travel in waves and have short wavelengths at high frequencies: *travel @ the speed of light; *X-Rays photons interact with the materials they penetrate and the result is ionization |
| Contents of the Lead-lined glass tube (vacuum tube): Copper Stem | Dissipates heat away from the tungsten target |
| Contents of the Lead-lined glass tube (vacuum tube): Tungsten target | Converts electrons into X-Ray photons |
| Contents of the Lead-lined glass tube (vacuum tube): Molybdenum Focusing Cup | Focuses electrons into a narrow beam and directs it towards the tungsten target |
| Contents of the Lead-lined glass tube (vacuum tube): Filament | Produces electrons when activated by heat |
| Components of the X-Ray Tubehead: Radiator | Cools the machine by releasing heat |
| Components of the X-Ray Tubehead: Aluminum Disks/ ALumin Filter | FIlte rout longer wavelength (low energy) x-rays |
| Components of the X-Ray Tubehead: Lead collimator (diaphragm) | *Restrits the size of the X-Ray bem; *Lead plate w/ a central opening |
| Components of he X-Ray Tubehead: Transformers | alter the voltage of electricity coming into tubehead |
| Dissipates heat away from tungsten target | Component of lead-lined glass tube: copper stem |
| Converts electrons into X-ray photons | Component of lead-lined glass tube: tungsten target |
| Focuses electrons into a narrow beam and directs it towards the tungsten target | Component of lead-lined glass tube: Molybdenum Focusing cup |
| Produces electrons when activated by heat | Component of lead-lined glass tube: filament |
| Alter the voltage of electricity coming into the tubehead | Transformers |
| Cools the machine by releasing heat | Component of the X-Ray tubehead: radiator |
| Filter out longer wavelength (low-energy) x-rays | Component of the X-Ray tubehead: aluminum disks, aluminum filter |
| *Restricts the size of the x-ray beam; *lead plate w/a central opening | Component of the X-Ray tubehead: Lead collimator (diaphragm) |
| Cathod, what type of electrode and consists of what? | Cathode is a negative electrode, and consists of filament and molybdenum focusing cup. |
| Negative electrode that consists of molybdenum focusing cup and filament is known as | Cathode |
| Anode, what type of electrode and consists of what? | Anode, is a positive electrode and consists of the tungsten target and copper stem. |
| Positive electrode that consists of the tungsten targer and copper stem is called | Anode |
| Electric current is | flow of electrons through a conductor (measured in mA) |
| Flow of electrons through a conductor is | Electric current |
| Electric current is measured in | milliamperes (mA) |
| What is measured in milliamperes (Ma) | electric current |
| what is Voltage | Voltage is a measurement of electric force that causes electrons to move from a negative pole to a positie one; |
| Measurement of electric force, that causes electrons to move from a negative pole to a positive one. | Voltage |
| Voltage is measured in | kV (kilovolts) |
| What is measured in kV? | (kilovolts) Voltage |
| Transformer is... | Device that either increases or decreases voltage in an electrical circuit |
| Device that either increases or decreases voltage in an electrical circuit is... | transformer |
| What does transformer do: | 1)Transformer is a device that either increases or decreases voltage in an electrical circuit; 2)Alters the voltage of the incoming electrical current, and then sends the electrical energy to the x-ray tube; |
| What are the 2 transformers in the X-Ray tube? | 1)Step-up transformer (increases voltage) 2)Step-down transformer (reduces voltage from 110-220v to 3-5 volts to heat the filament; |
| Step-down transfromer which reduces the voltage is controlled by the... | milliamperage setting (mA) |
| What is the voltage necessary to heat up the filament inside the tubehead, and how is it done | The voltage necessary to heat up the filament is 3-5 volts; it is controlled by the step-down transformer that reduces voltage from 110-220 volts |
| What is the voltage necessary for production of X-Ray beam? | 65,000-100,000 necessary for production of x-ray beam |
| When the electrons strike the tungsten target their energy is converted to | X-ray energy and heat; 1% of the energy is x-rays; 99% of the energy is heat |
| When the electrons strike the tungsten target teir energy is converted to x-ray energy and heat. What is the percentage of energy and heat produced? | 1% of the energy is x-rays; 99% of the energy is heat |
| Types of X-Radiation | 1)Primary Radiation; 2)Secondary Radiation; 3)Scatter Radiation |
| Primary Radiation, describe | The penetrating x-ray beam produced at the tungsten target; useful beam; |
| Secondary Radiation, describe | X-Radiation that is created when the primary beam interacts with matter (soft tissues, bones, teeth); Less penetrating than primary radiation |
| Statement: Secondary Radiation is less penetrating than the primary radiation | True |
| Statement: Secondary Radiation is more penetrating than the primary radiation. | False |
| Scatter Radiation, describe | Form of secondary radiation that has been deflected from its path by interaction with matter (hard and soft tissues); *Travels to different parts of the body and throughout the dental operatory; *Detrimental (harmful) to pt and operator; |
| 3 Possible Radiation Interactions (when it is released): | 1)An X-Ray photon can pass through the pt without any interaction with biological tissues; 2)An X-Ray photon can be entirely absorbed by the pt (known as photoelectric effect); 3)X-Ray photons are scattered; |
| Photoelectric effect | When the photon collides w/an inner-shell electron giving up all of its energy to eject the electron from its orbit (In Radiation Interaction: when an X-Ray photon can be entirely absorbed by pt) |
| When the photon collides with an inner-shell electron giving up all of its energy to eject the electron from its orbit, known as | photoelectric effect |
| Compton scatter is a type of | Scatter Radiation |
| What represents 62% of all scatter radiation | Compton scatter |
| Compton scatter represents how much percent of the scatter radiation | 62% |
| Compton Scatter, describe | X-Ray photon collides w/an electron inthe outer shell of an atom, & theelectron is ejected from its orbit *the x-ray photon now has less energy &travels in adiffrnt direction (scatters) @low energy *The ejected electron is referrd to as a Compton electron |
| In dental radiography, the quality of the X-Ray beam is controlled by | kilovoltage peak (kVp) |
| 70 kVp = | 70,000 volts |
| Varying voltages in the tube current result in a polychromatic x-ray beam, means | beam that contains many different wavelengths of varying inensities; |
| Kilovoltage peak refers to the | energy and penetrating ability of the x-ray beam |
| An increase in the kVp (kilovoltage peak) results in a (what beam?) | high-energy x-ray beam w/increased penetrating power; |
| An increase in kVp and its effect on the image density | Overall darkness/blackness of the image receptor |
| Low kVp and its effect on the receptor contrast | High contrast receptor (many black and white areas w/few shades of gray) |
| High kVp and its effect on the receptor contrast | low contrast receptor (many shades of gray instead of black and white) |
| Low kVp and its effect on receptor density | decreased density; overall light image |
| Exposure time, define | Interval of time in which x-rays are produced |
| Exposure time measured in... | impulses |
| What is measured in impulses | Exposure time |
| Impulses, define | creation of x-rays occurs in series of bursts rather than in a continuous stream |
| One impulse occurs | very 1/60 of a second (60 impulses per second) |
| How many impulses are there per second | 60 |
| A maxillary molar periapical radiograph is taken with an exposure time of .32 seconds. To calculate the equivalent number of impulses: | .32 X 60 (60 impulses per second) = 19.2 impulses |
| When kVp (kilovoltage peak) is decreased what must be done to exposure time to maintain proper density and contrast of the receptor | Exposure time must be increased |
| Kilovoltage peak rule: When kVp is increased by 15, exposure time should be | decreased by one-half (Kilovoltage peak rule: if 60 kVp is increased to 75 kVp, exposure time must be decreased from 1.0 to .5) |
| In dental radiography, the quantity of radiation produced is controlled by: | milliamperage |
| Milliamperage controls the | quantity or number of x-rays emitted from the tubehead by regulating the temperature of the filament |
| What controls the quantity or number of x-rays emitted from the tubehead by regulating the temperature of the filament | Milliamperage (mA) |
| high mA affects/equals: | increased temperature of filament = increased number of electrons produced by the filament; *an increase in electrons = increased number of x-rays emitted from the tubehead |
| when mA is increased, number of X-Ray is | increased |
| When mA is increased, what must be done to the exposure time | Exposure time must be decreased to maintain image receptor density |
| Intensity of the X-ray beam, define | Quality (energy of the x-ray beam) and quantity (number of x-ray photons in the beam) of x-ray photons per unit of area per unit of exposure time; |
| Intensity of the X-Ray beam affected by: | *kVp; *mA; *Exposure time; *Distance |
| Inverse Square Law. Explains how distance affects the intensity of the x-ray beam | Distance and intensity are inversel proportional; as one increases, the other decreases |
| Ionizing Radiation can be classified into 2 groups: | 1) Particulate Radiation and 2)Electromagnetic Radiation |
| Particulate Radiation is a subgroup of | Ionizing Radiation |
| Particulate Radiation is | Particles of matter that have mass and travel in straight lines at high speeds. Includes electrons, protons, neutrons, and alpha particles; |
| Particulate Radiation includes | electrons, protons, neutrons, and alpha particles |
| What is characterized as: "particles of matter that have mass and travel in straight lines at high speeds"? | Particulate Radiation (a subgroup of Ionizing Radiation) |
Created by:
EdmondDantes