Quiz questions Part I-III Flashcards
What is the name of the cell death triggered by hydrogen peroxide?
Apoptosis
Apoptosis is programmed cell death, often triggered by oxidative stress from hydrogen peroxide.
What is the principal difference between mass and weight?
Mass is the equivalent of energy; weight is the force exerted by gravity.
Mass remains constant, while weight depends on gravity.
Collimation and filtration do which of the following?
Reduce patient dose
They remove low-energy x-rays that would increase radiation dose without contributing to image formation.
Roentgen originally identified x-rays as which of the following?
X-light
Roentgen called them “X-light” because their nature was unknown.
Which of the following items is considered to be matter?
Wet snow
Matter has mass and occupies space, as opposed to energy forms like light or radiation.
What is special about the atom after alpha and/or beta decay?
A change in element
Alpha and beta decay change the number of protons, converting the atom into a different element.
No valence shell of an atom can contain more than how many electrons in reality?
8
The octet rule states that atoms are stable with 8 electrons in their outermost shell.
The absorption of electromagnetic energy is an all-or-nothing event. What is this process called?
Absorption
X-ray photons are either absorbed entirely or not at all in the photoelectric effect.
Which of the following is expressed in the proper SI units?
Exposure: mGy
Exposure is measured in milligray (mGy), a standard SI unit.
This type of emission occurs when the nucleus of an atom becomes unstable, and alpha particles are emitted to restore balance.
Alpha emission
Alpha decay occurs in heavy isotopes with a neutron-to-proton ratio that is too low.
Atoms that have the same number of neutrons but different numbers of protons are called what?
Isotones
Isotones have the same number of neutrons but different atomic numbers.
This bond is characterized by the attraction of opposite electrostatic charges.
Ionic
Ionic bonds form between positive and negative ions, such as in salts.
Isotopes are atoms that have what in common?
The same element
Isotopes have the same number of protons but different numbers of neutrons.
The longer the wavelength, the ________ the energy.
Less
Energy is inversely proportional to wavelength (E = hf).
Which scientist developed the fluoroscope?
Thomas Edison
Thomas Edison invented the fluoroscope, an early real-time x-ray imaging device.
What is the atomic number?
The number of protons
The atomic number represents the number of protons in an element, defining its identity.
Which of the following imaging modalities was developed most recently?
Multislice spiral CT
Multislice CT is a more modern imaging technique compared to ultrasound, MRI, and direct digital radiography.
What is the largest component of an atom?
Empty space
Atoms are mostly empty space, with a dense nucleus at the center.
Superficial x-ray applications operate in what energy range?
50 to 100 kVp
Superficial x-rays use lower energy compared to diagnostic and therapeutic x-rays.
What is the only atom that has an atomic mass equal to its atomic mass number?
Carbon
The atomic mass of carbon-12 equals its mass number (12).
What was the device with which Roentgen discovered x-rays?
Crookes tube
Roentgen used a Crookes tube to observe x-ray emissions for the first time.
Which component of the x-ray tube generates the flow of electrons?
Anode stator
The anode stator rotates the anode, controlling electron interactions.
Which of the following is expressed in the proper SI units?
Exposure: Gy
Gray (Gy) is the SI unit for radiation absorbed dose.
Losing an electron makes an atom _______.
Ionized
An atom that loses an electron becomes positively charged (a cation).
Which of the following temperature conversions is correct?
K = C + 273
The Kelvin scale is derived from Celsius by adding 273.
This type of emission occurs when the neutron-to-proton ratio is too high, and a neutron transforms into a proton and an electron.
Beta emission
Beta decay involves a neutron splitting into a proton and an electron, with the electron being emitted.
In atomic nomenclature, the number of protons is represented by which letter?
Z
The atomic number (Z) represents the number of protons.
The velocity of all electromagnetic radiation is ______.
3.0 × 10⁸ m/s
The speed of light is constant for all electromagnetic radiation in a vacuum.
Atoms that have the same atomic number but different atomic mass numbers are called what?
Isotopes
Isotopes differ in neutron count but have the same number of protons.
One tenth-value layer is equivalent to how many half-value layers?
3.3
One TVL (Tenth-Value Layer) reduces radiation to 10%, equivalent to approximately 3.3 HVLs.
An alpha particle is a helium nucleus that contains what?
Two protons and two neutrons
Alpha particles are helium nuclei with a charge of +2.
Frequency (f) is typically measured in what units?
Hertz (Hz)
Frequency is the number of cycles per second, measured in hertz.
Electron binding energy is greatest in which shell?
K-shell
The K-shell (closest to the nucleus) has the highest binding energy due to strong nuclear attraction.
What term is used to describe the x-ray beam after it leaves the patient’s body and before it reaches the image receptor?
Remnant radiation
Remnant radiation is the portion of the primary x-ray beam that passes through the patient and carries the image information.
What device is used to restrict the size and shape of the x-ray field?
Collimator
A collimator helps control scatter radiation by limiting the field size, improving image quality and reducing patient dose.
Which factor has the greatest impact on image contrast in digital radiography?
kVp
Higher kVp reduces contrast by increasing Compton scatter, while lower kVp increases contrast by enhancing the photoelectric effect.
The overall darkness or blackness of a radiographic image is referred to as what?
Radiographic density
Density refers to the amount of blackening on a film image, which is controlled by mAs in conventional radiography.
What effect does increasing SID (source-to-image distance) have on image sharpness?
Increases sharpness
Increasing SID reduces geometric unsharpness (penumbra), leading to better image detail.
What is the inverse square law, and how does it affect x-ray intensity?
X-ray intensity is inversely proportional to the square of the distance
Doubling the distance reduces intensity to one-fourth, while halving the distance increases intensity fourfold.
The difference in optical density between adjacent structures on a radiographic image is called what?
Contrast
Contrast refers to the visible differences in grayscale that allow structures to be distinguished.
What effect does increasing kVp have on Compton scatter?
Increases scatter
Higher kVp increases photon energy, which leads to more Compton scatter, reducing contrast and increasing fog.
What is the term for magnification caused by a large OID (object-to-image distance)?
Size distortion
When an object is far from the detector, it appears larger due to geometric magnification.
Which exposure factor is primarily responsible for controlling x-ray beam penetration?
kVp
kVp determines x-ray energy and its ability to penetrate tissue, affecting image contrast and patient dose.
Which of the following reduces scatter radiation and improves contrast in an x-ray image?
Using a grid
Grids absorb scattered photons before they reach the image receptor, enhancing contrast by reducing fog.
What happens to x-ray beam intensity when filtration is increased?
Beam intensity decreases
Filtration removes low-energy photons, reducing overall beam intensity while increasing average energy (beam hardening).
What does mAs primarily control in an x-ray image?
X-ray quantity (image brightness/density)
mAs directly affects the number of x-ray photons produced, influencing image exposure and patient dose.
Which of the following factors can reduce motion blur on an image?
Decreasing exposure time
A shorter exposure time minimizes motion artifacts by reducing the time in which the patient can move.
What does high contrast in an image mean?
Few shades of gray (short grayscale)
High contrast results from lower kVp, creating a more black-and-white image with distinct differences between densities.
What type of contrast is produced by a high kVp technique?
Low contrast (long grayscale)
High kVp produces more penetrating x-rays, reducing differential absorption and increasing grayscale range.
What is the primary function of a grid in radiographic imaging?
Absorbs scatter radiation before it reaches the image receptor
Grids improve image contrast by preventing scattered x-rays from fogging the image.
How does increasing OID (object-to-image distance) affect image sharpness?
Decreases sharpness
A greater OID increases the penumbra (blur) effect, reducing spatial resolution.
What is the purpose of beam restriction devices like collimators?
Limit patient exposure and reduce scatter radiation
Beam restriction narrows the field size, decreasing unnecessary radiation and improving contrast.
What does the term penumbra refer to in radiographic imaging?
Geometric unsharpness around the edges of an object
Penumbra results from the finite size of the x-ray focal spot, causing edge blurring.
What is the primary advantage of using a longer SID?
Reduces image distortion and increases sharpness
A longer SID minimizes beam divergence, reducing size distortion and improving spatial resolution.
What is the primary reason for using an intensifying screen in film-based radiography?
Reduces patient dose
Intensifying screens amplify x-ray photons, requiring lower exposure and reducing patient radiation dose.
Which of the following reduces both patient dose and image noise?
Increasing kVp while reducing mAs
Higher kVp increases penetration while allowing lower mAs, reducing dose and quantum noise.
What is the result of using a small focal spot size?
Increases image sharpness
A smaller focal spot reduces penumbra, leading to better spatial resolution and finer detail.
What effect does using a grid have on exposure factors?
Requires an increase in mAs
Grids absorb scatter but also primary x-rays, so mAs must be increased to maintain exposure.
What is the most effective way to reduce voluntary motion on an x-ray?
Clear communication with the patient
Instructing the patient properly helps prevent motion blur from unnecessary movement.
What is the purpose of the anode heel effect in x-ray imaging?
Causes intensity variation across the x-ray field
The heel effect results from x-ray absorption in the anode, making the beam weaker on the anode side.
What is the function of scatter radiation in diagnostic imaging?
It reduces image contrast and can cause fogging
Scatter radiation adds unwanted exposure, decreasing the ability to distinguish fine details.
What is the primary reason for using a high-frequency generator in modern x-ray systems?
It produces a more efficient and consistent x-ray output
High-frequency generators provide nearly constant voltage, reducing voltage ripple and improving image quality.
What is the effect of increasing focal spot size on spatial resolution?
Decreases resolution
A larger focal spot increases penumbra (edge blur), reducing sharpness.
What happens when x-ray photons interact with air?
Minimal attenuation occurs
Air has a very low atomic number, so it absorbs almost no x-rays, allowing most photons to pass through.
What is the purpose of exposure timers in an x-ray system?
Regulate the duration of x-ray exposure
Timers control how long x-ray photons are produced, preventing overexposure and excessive radiation dose.
Which type of body habitus represents the largest patient body type?
Hypersthenic
Hypersthenic patients have a broader, more massive build, requiring higher exposure settings due to increased tissue density.
What is the most common method of measuring patient radiation dose?
Entrance Skin Exposure (ESE)
ESE measures the radiation dose received at the skin surface, which is the highest dose the patient receives.
Which type of imaging system has the best contrast resolution?
MRI
MRI provides excellent soft tissue contrast due to differences in proton density and relaxation times.
Which part of the x-ray tube is responsible for producing free electrons?
Filament
The filament is heated to release electrons through thermionic emission, which are then accelerated to produce x-rays.
What is the function of the focusing cup in an x-ray tube?
Directs the electron beam toward the anode
The focusing cup is negatively charged and helps concentrate electrons into a narrow stream, preventing electron spread.
What is the primary purpose of the anode in an x-ray tube?
To stop the electron stream and produce x-rays
When high-speed electrons strike the anode target, their kinetic energy is converted into x-ray photons and heat.
What is the most common target material used in diagnostic x-ray tubes?
Tungsten
Tungsten is used due to its high atomic number, high melting point, and excellent heat dissipation properties.
What is the purpose of the glass envelope in an x-ray tube?
Maintains a vacuum
The vacuum prevents air molecules from interfering with electron movement, ensuring efficient x-ray production.
What percentage of electron kinetic energy is converted to x-rays in the anode?
Less than 1%
Approximately 99% of the energy is converted into heat, while only 1% is converted into x-ray photons.
What does the rotating anode do in an x-ray tube?
Spreads heat over a larger surface area
Rotation allows different parts of the anode to receive heat, reducing the risk of damage and increasing tube longevity.
What is the advantage of a high-speed rotating anode?
Better heat dissipation and longer tube life
Higher rotation speeds reduce overheating and extend the anode’s durability, allowing higher exposure techniques.
What is the line-focus principle?
Angling the anode to create a smaller effective focal spot
This improves image resolution while allowing a larger actual focal spot to handle higher heat loads.
What is the purpose of the heel effect in x-ray production?
Causes uneven x-ray intensity, with stronger radiation on the cathode side
The heel effect is due to x-ray absorption in the anode, affecting beam intensity distribution.
How does increasing kVp affect x-ray tube output?
Increases both quantity and quality of x-rays
Higher kVp increases photon energy and penetration, as well as the total number of x-rays produced.
What material is commonly used in x-ray tube filtration?
Aluminum
Aluminum effectively removes low-energy x-rays, reducing patient dose while maintaining image quality.
What does added filtration do to the x-ray beam?
Increases average beam energy (beam hardening)
Filtration removes low-energy photons, increasing the overall penetrating ability of the x-ray beam.
What is the primary purpose of added filtration in an x-ray tube?
To reduce patient skin dose
By eliminating low-energy x-rays that would be absorbed by the skin, filtration decreases unnecessary radiation exposure.
What happens to the x-ray beam intensity when filtration is increased?
Decreases intensity while increasing average energy
More filtration means fewer x-ray photons overall, but those that remain are higher energy.
What is the difference between inherent and added filtration?
Inherent is built into the tube; added is externally placed
Inherent filtration includes the glass envelope and cooling oil, while added filtration consists of aluminum plates outside the tube.
What is the purpose of compensating filters in radiography?
To even out exposure in body parts of varying thickness
Filters like wedge or trough filters adjust x-ray intensity to prevent overexposure of thinner body areas.
What type of radiation is produced outside the focal spot?
Off-focus radiation
These are x-rays produced by electrons striking areas of the anode outside the intended focal spot, contributing to image blur.
What is the primary function of the x-ray tube housing?
To reduce leakage radiation and provide mechanical support
The housing contains lead shielding to prevent excess radiation from escaping, ensuring safety compliance.
What is leakage radiation?
Radiation that escapes from the tube housing in unintended directions
Leakage is controlled by regulatory limits and should not exceed 1 mGy per hour at 1 meter distance.
What is the purpose of the stator and rotor assembly in the x-ray tube?
Rotates the anode for better heat dissipation
The stator (electromagnetic) and rotor (mechanical) work together to spin the anode, preventing overheating.
What factor determines the effective focal spot size?
The anode angle
A steeper anode angle results in a smaller effective focal spot, improving image resolution.
What is the primary advantage of a smaller focal spot?
Better spatial resolution
A smaller focal spot produces sharper images with finer detail, though it has a lower heat capacity.
What is the minimum total filtration required for x-ray tubes operating above 70 kVp?
2.5 mm Al equivalent
Regulatory guidelines require a minimum of 2.5 mm aluminum equivalent for patient radiation protection.
What is meant by heat capacity in an x-ray tube?
The ability to store and dissipate heat without damage
The anode must withstand repeated exposures without overheating or cracking.
What determines the anode’s ability to handle heat?
Focal spot size, anode rotation speed, and material
A larger focal spot, faster rotation, and tungsten target improve heat handling capability.
What is the purpose of the tube rating chart?
To determine safe exposure limits without damaging the tube
This chart helps technologists avoid exceeding heat capacity during x-ray exposures.
What is the most common cause of abrupt x-ray tube failure?
Tungsten vaporization from the filament
Over time, tungsten evaporates from the filament, leading to arcing and electrical failure.
What does the anode warm-up procedure prevent?
Thermal shock and anode cracking
Gradually warming up the anode prevents sudden expansion that can cause structural damage.
What is the main advantage of a dual-focus x-ray tube?
It has two focal spot sizes for different imaging needs
A smaller focal spot provides better resolution, while a larger one handles higher exposures to prevent overheating.
What happens to the effective focal spot size when the anode angle is reduced?
It becomes smaller
A steeper anode angle creates a smaller effective focal spot, improving image sharpness but reducing the heat capacity.
How does increasing tube current (mA) affect x-ray production?
Increases the number of x-ray photons produced
Higher mA generates more electrons at the filament, increasing the quantity of x-rays without changing beam energy.
What happens if the x-ray tube is operated above its heat capacity?
It may cause tube damage or failure
Exceeding heat limits can result in anode pitting, cracking, or complete tube burnout.
What is the purpose of a heat unit (HU) calculation?
To determine how much heat is generated in the x-ray tube
Heat unit calculations help technologists ensure safe operation by monitoring cumulative heat load.
Why are rotating anodes made of a tungsten-rhenium alloy?
It improves durability and heat resistance
Rhenium strengthens the tungsten target, preventing cracking and increasing the anode’s lifespan.
