Matter & Energy Quiz
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Questions and Answers

Which type of energy is described as the energy of motion at the atomic and molecular level?

  • Thermal Energy (correct)
  • Electromagnetic Energy
  • Electrical Energy
  • Nuclear Energy

    • What distinguishes matter from other entities in the physical world?

  • Volume
  • Mass (correct)
  • Weight
  • Density

    • Which form of energy is contained within the nucleus of an atom?

  • Nuclear Energy (correct)
  • Chemical Energy
  • Thermal Energy
  • Mechanical Energy

    • What type of radiation is NOT considered ionizing radiation?

    <p>Ultrasound</p> Signup and view all the answers

    Electrical energy is produced when an electron moves through which of the following?

    <p>Electrical potential difference</p> Signup and view all the answers

    What is the nature of uncharged particles regarding electric fields?

    <p>They do not have electric fields.</p> Signup and view all the answers

    What does the Law of Conservation of Energy state?

    <p>Energy can be transformed but not created or destroyed.</p> Signup and view all the answers

    Which of the following describes Coulomb’s Law?

    <p>The electrostatic force is directly proportional to the product of charges and inversely proportional to the square of the distance.</p> Signup and view all the answers

    Which wavelength range is associated with electromagnetic radiation?

    <p>10-10 to 10-14 m</p> Signup and view all the answers

    What effect does an electric field have on charged particles?

    <p>It causes charged particles to move from one pole to another.</p> Signup and view all the answers

    How is the frequency of electromagnetic radiation quantified?

    <p>$10^{18}$ to $10^{22}$ Hz</p> Signup and view all the answers

    What determines the movement of charged particles in an electric field?

    <p>The polarity of the electric field.</p> Signup and view all the answers

    What is a characteristic of materials that can be conductive?

    <p>They can allow the flow of electric current.</p> Signup and view all the answers

    What is a defining characteristic of superconductors?

    <p>They have no resistance below a critical temperature.</p> Signup and view all the answers

    What is required for a conductor to allow electrons to flow easily?

    <p>An applied voltage.</p> Signup and view all the answers

    How is electric resistance measured?

    <p>In Ohms.</p> Signup and view all the answers

    Which of the following substances is an example of an insulator?

    <p>Rubber.</p> Signup and view all the answers

    What are semiconductors characterized by?

    <p>Behaving as insulators or conductors depending on conditions.</p> Signup and view all the answers

    What happens to electric current when electric resistance increases?

    <p>It decreases.</p> Signup and view all the answers

    What does Ohm's Law describe?

    <p>The relationship between voltage, current, and resistance.</p> Signup and view all the answers

    What distinguishes alternating current from direct current?

    <p>The current alternates direction.</p> Signup and view all the answers

    What characteristic do conductors and superconductors share?

    <p>Both allow electric charge to flow with no resistance.</p> Signup and view all the answers

    Which of the following materials demonstrates high resistance, making it an insulator?

    <p>Clay.</p> Signup and view all the answers

    What is the primary blood cell type affected first within minutes to hours after exposure?

    <p>Lymphocytes</p> Signup and view all the answers

    What is the total equivalent dose for an embryo fetus for the entire gestation period?

    <p>5 mSv</p> Signup and view all the answers

    What is the recovery time for granulocytes and thrombocytes after irradiation?

    <p>2 months</p> Signup and view all the answers

    Which safety principle significantly reduces radiation exposure when positioning shielding?

    <p>Shielding</p> Signup and view all the answers

    What is the relationship between radiation-induced chromosome aberrations and radiation dose?

    <p>Non-threshold dose response</p> Signup and view all the answers

    How long does it take for erythrocytes to fully recover after radiation exposure?

    <p>6 months to 1 year</p> Signup and view all the answers

    What is the thickness of the absorber equivalent to one TVL in reducing radiation intensity?

    <p>3.3 cm</p> Signup and view all the answers

    What percentage of occupational exposure can protective aprons reduce?

    <p>25%</p> Signup and view all the answers

    What is the primary function of the high voltage generator in an x-ray system?

    <p>To increase the output voltage necessary for x-ray production</p> Signup and view all the answers

    Which timing circuit is able to measure time intervals as small as 1 ms?

    <p>Electronic Timer</p> Signup and view all the answers

    How does the falling load generator minimize exposure time?

    <p>By beginning at maximum mA and then decreasing</p> Signup and view all the answers

    What role do precision resistors serve in the x-ray system?

    <p>To reduce voltage to a level suitable for selected milliamperage</p> Signup and view all the answers

    What is the purpose of the Automatic Exposure Control (AEC) in an x-ray system?

    <p>To automatically terminate exposure when a predetermined radiation intensity is reached</p> Signup and view all the answers

    What does the space charge effect refer to in x-ray production?

    <p>Electrostatic repulsion of the electron cloud near the filament</p> Signup and view all the answers

    What describes the signal from the MA meter in an x-ray system?

    <p>It monitors the x-ray tube current</p> Signup and view all the answers

    What is the relationship between the turns ratio and voltage in a transformer?

    <p>Directly proportional to voltage and inversely proportional to current</p> Signup and view all the answers

    Which component is primarily responsible for converting AC to DC in an x-ray system?

    <p>Rectifiers</p> Signup and view all the answers

    Which type of semiconductor has loosely bound electrons?

    <p>P-type semiconductor</p> Signup and view all the answers

    What is the primary limitation of a single-phase power x-ray system?

    <p>Results in a pulsating x-ray beam with zero output at some points</p> Signup and view all the answers

    What distinguishes a full-wave rectification from half-wave rectification?

    <p>It cuts exposure time in half</p> Signup and view all the answers

    In a high voltage transformer, how is the secondary current related to the primary current?

    <p>Secondary current is less than primary current</p> Signup and view all the answers

    What is a primary advantage of using a three-phase power system?

    <p>The voltage remains constant during exposure</p> Signup and view all the answers

    What is thermionic emission in the context of x-ray production?

    <p>The release of electrons from a heated filament</p> Signup and view all the answers

    Study Notes

    Matter & Energy

    • Matter is anything that occupies space and has mass.
    • Mass is the distinguishing characteristic of matter and is measured in kilograms.
    • Atoms are the building blocks of matter.
    • Energy is the ability to do work.
    • Electrical energy is produced when an electron moves through an electrical potential difference.
    • Thermal energy is the energy of motion at the atomic and molecular level.
    • Nuclear energy is energy contained in the nucleus of an atom.
    • Electromagnetic energy (EMR) is radiation and is a transfer of energy.
    • Ultrasound is a form of radiation but not ionizing radiation.

    Laws of Conservation

    • Law of Conservation of Matter: Matter can neither be created nor destroyed.
    • Law of Conservation of Energy: Energy may be transformed from one form to another, but cannot be created or destroyed.
    • Coulomb's Law: The electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them.
    • Law of Distribution: Electric charge distribution of charges is uniform throughout or on the surface.

    Electrodynamics

    • The study of electric charge in motion.

    Conductors

    • Substances through which electrons flow easily.
    • Require voltage to move the electron.
    • Characteristics:
      • Variable resistance
      • Obeys Ohm's Law
    • Examples: Copper, Aluminum, & Water

    Insulator

    • Substances that do not allow electrons to flow.
    • Characteristics:
      • Extremely high resistance
      • Necessary with high voltage for insulation (to protect from electrocution)
    • Examples: Glass, Rubber, & Clay

    Semiconductors

    • Materials that sometimes behave as insulators and sometimes as conductors.
    • Characteristics:
      • Can be resistive
      • Can be conductive
      • Basis of computers
    • Examples: Silicon, & Germanium

    Superconductor

    • Materials that allow electrons to flow without resistance.
    • Characteristics:
      • No resistance
      • No electrical potential required (voltage)
      • Must be very cold/extreme low temperature
    • Examples: Niobium and titanium

    Superconductivity

    • The property of some matter to exhibit no resistance below a critical temperature.

    Electric Circuits

    • The path of electron flow from the generating source through the various components and back again.

    Electric Current/Electricity

    • Flow of electrons through a conductor.
    • Direction: Always opposite the electron flow.
    • Measured in Amperes (A)

    Electric Resistance

    • Measured in ohms.
    • Increasing electric resistance results in a reduced electric current.

    Ohm's Law

    • The voltage across the total circuit or any portion of the circuit is equal to the current times the resistance.
    • Formula: V = I x R

    Alternating Current (AC)

    • Electrons flow alternately in opposite directions.
    • Electrons flow first in a positive direction and then in a negative direction.
    • Sinusoidal wave.

    Magnetism

    • Oxide of iron (Fe3O4)
    • A rodlike stone moving back and forth also called as lodestone or leading stone.

    Magnetic Field

    • Any charged particle in motion creates a magnetic field.
    • Magnetism controls the kVp and operates as an induction device.

    High Voltage Generator

    • Housed in an equipment cabinet positioned against a wall, close to the x-ray tube.
    • Newer generator designs take up less space.
    • Reduces patient radiation dose.

    Operating Console

    • Most familiar to the radiologic technologist.
    • Used to control the x-ray tube current and voltage applied to the xray tube.
    • Provides control of:
      • Line compensation
      • kVp
      • mA
      • Exposure time
    • Most xray systems are designed to operate on 220v power.

    Radiation Quantity (mAs)

    • Number of x-rays.
    • Intensity of the x-ray beam.
    • Controlling factor of current.
    • High number of electrons, higher heat provided to the x-ray tube.
    • Units: mR, mGy or mR/mGya, mAs.

    Autotransformer Law

    • States that the voltage received and provided by the transformer is directly proportional to the number of turns.
    • Vs/Vp = Ns/Np

    kVp Meter

    • Placed across the output terminals of the autotransformer.
    • Actually reads voltage, not kVp.
    • Pre-reading kVp meter: Allows the voltage to be monitored before an exposure.

    Filament Temperature

    • Controlled by the filament current, determines the number of electrons emitted by the filament.

    Filament Current

    • Measured in Ampheres (A).
    • X-ray tube is controlled through a separate circuit called Filament Circuit.
    • Operates at currents of 3 to 6 Ampere.

    Space Charge Effect

    • Phenomena via electrostatic repulsion.
    • Electron cloud near the filament.

    Thermionic Emission

    • Release of electrons from a heated filament.

    Precision Resistors

    • Used to reduce the voltage to a value that corresponds to the selected milliamperage.

    Falling load generator

    • Exposure begins at maximum mA, then drops as the anode heats, which results in minimum exposure time.

    mA x Exposure Time (mAs)

    • Product of x-ray tube current (mA) and exposure time is mAs.
    • Measure of Electrostatic Charge (C).

    mA meter

    • Monitors the x-ray tube current.
    • Connected at the center of the secondary winding of the high-voltage setup transformer.
    • Ensures electrical safety.

    Filament Transformer

    • "Filament heating isolation step-down transformer".
    • Receives the voltage from the mA selector switch.
    • Steps down the voltage to approx.. 12 v.
    • Provides current to heat the filament.
    • Primary winding: Thin copper, 0.5 to 1Ampere, 150v approximately.
    • Secondary winding: Thick, 5 to 8Ampere, 120 V.

    Exposure Timers

    • Devices that control the duration of x-ray exposure.

    Guard Timer

    • Terminate exposure after a prescribed time (6s).

    Synchronous Timer

    • Motor driven.
    • Precision device designed to drive a shaft at precisely 60 rev per second.
    • Cannot be used for serial exposures.

    Electronic Timer

    • Most sophisticated, complicated, and accurate of the x-ray exposure timers.
    • Allows a wide range of time intervals to be selected and are accurate to intervals as small as 1ms.
    • Used for rapid serial exposures, suitable for interventional radiology.
    • Most exposure timers are Electronic.

    mAs Timer

    • Monitors the product of mA and exposure time (Electrostatic Charge – C).
    • Terminates exposure when the desired mAs value is reached.
    • Provides the highest safe tube current for the shortest exposure for any mAs selected.

    Automatic Exposure Control (AEC)

    • Device that measures the quantity of radiation that reaches the IR.
    • Automatically terminates the exposure when the IR has received the required radiation intensity.

    Solid-State Detectors (SSD)

    • Used to check timer accuracy (as short as 1 ms)

    High Voltage Generator

    • Increases the output voltage from the autotransformer to the kVp necessary for x-ray production.
    • Heat generated is conducted by the oil, which is used primarily for electrical insulation (DIALA V OIL).
    • Three primary parts:
      • High voltage transformer
      • Filament transformer
      • Rectifiers

    High Voltage Transformer

    • Step Up Transformer.
    • Secondary Voltage (kVp) > Primary Voltage (V)
    • Secondary Current (mA) < Primary Current (A)
    • Secondary Windings > Primary Windings
    • Voltage waveform: Sinusoidal.

    Turns Ratio

    • Ratio of the number of secondary windings to the number of primary windings.
    • Example: 500:1 and 1000:1.
    • Directly proportional to the voltage.
    • Inversely proportional to the current.

    Rectification

    • Process of converting AC to DC.
    • X-rays are only produced by the acceleration of electrons from cathode to the anode and cannot be produced by electrons flowing in the reverse direction (Direct Current).

    Voltage Rectification

    • Ensures that electrons flow from cathode to anode only.

    Rectifier

    • Electronic device that allows current to flow in only one direction.

    Diode

    • Electronic device that contains two electrodes.
    • All diode rectifiers were vacuum tubes called Valve tubes (Replaced by Solid-State Rectifiers made up of Silicon).

    Semiconductor

    • Between Insulator and conductor in the ability to conduct electricity.

    P-type Semiconductor

    • Have loosely bound electrons (free to move).
    • Have spaces called holes (no electrons).
    • Holes: As mobile as electrons.

    Solid-State P-N Junction

    • N-type material placed in contact with p-type crystal.
    • It conducts electricity in only one direction.
    • Solid-State Diode: A rectifier.

    Half-Wave Rectification

    • Contains 0, 1, or 2 diodes.
    • Voltage is now allowed to swing negatively during the negative half of its cycle.
    • Producing 60 x-ray pulses/per second.
    • Wastes half the supply of power and requires twice the exposure time.

    Full-Wave Rectification

    • Contains at least 4 diodes.
    • Negative half-cycle corresponding to the inverse voltage is reversed.
    • 120 x-ray pulses/second.
    • Exposure time is cut in half.
    • Used in almost all stationary x-ray.

    Single-Phase Power

    • Results in a pulsating x-ray beam.
    • X-rays produced have a value near zero.
    • Single Phase Halfwave voltage ripple: 100%
    • Single Phase Fullwave voltage ripple: 100%
    • Voltage varies from zero to maximum.

    Three-Phase Power

    • Voltage impressed across the x-ray tube is nearly constant.
    • 6 pulses per 1/60 second.
    • Voltage never drops to zero during exposure.
    • Has a disadvantage in terms of its size and cost.
    • Requires 10-kVp reduction.
    • 6-Pulse voltage ripple: 14%

    The X-ray Tube

    • Special type of diode - contains an anode and cathode.
    • Converts electrical energy to electromagnetic energy (x-rays).
    • Formula for single-phase power: (0.7)(mA x kVp)/1000

    Hematopoiesis Cell Survival

    • Exposure to radiation causes a decrease in the number of all types of blood cells in the circulating peripheral blood.
    • Lymphocytes are the first blood cells to be affected, depleting within minutes to hours after exposure.
    • Recovery of lymphocyte levels is very slow.
    • Granulocytes and thrombocytes are depleted 30 days after irradiation and take 2 months to recover.
    • Erythrocytes are less sensitive to radiation than other blood cells and take 6 months to 1 year to fully recover.

    Radiation Dose Limits

    • Students (over 18 years old) have a dose limit of 50 mSv.
    • General public has a dose limit of 1 mSv for frequent exposure and 5 mSv for infrequent exposure.
    • Embryos and fetuses have a total equivalent dose limit of 5 mSv for gestation, or 0.5 mSv per month.

    Cardinal Principles of Radiation Safety (STD)

    • Shielding: Positioning shielding between the radiation source and exposed personnel significantly reduces radiation exposure.
    • Time: Reducing the duration of exposure to radiation reduces the total radiation dose received.
    • Distance: Increasing the distance between the radiation source and exposed personnel reduces the intensity of radiation.

    Cytogenetics

    • The study of the genetics of cells (cell chromosomes).
    • Radiation-induced chromosome aberrations follow a non-threshold dose-response relationship, meaning that any dose of radiation can cause damage.

    Radiation Shielding

    • One TVL (tenth-value layer) is the thickness of absorber that reduces radiation intensity by 90%.
    • A protective apron containing 0.5 mm of lead is equivalent to 2 HVLs (half-value layers), reducing occupational exposure by 25%.
    • 1 TVL is equivalent to 3.3 HVLs.

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