2 xrays Flashcards
- What is the main cause of attenuation in an x-ray beam?
A) Reflection
B) Refraction
C) Absorption and scattering
D) Diffraction
C
- Which of the following processes produces characteristic radiation in x-ray imaging?
A) Compton scatter
B) Photoelectric effect
C) Bremsstrahlung
D) Elastic scattering
B
- What does the term “beam hardening” refer to in x-ray imaging?
A) Removal of high-energy photons from the beam
B) Removal of low-energy photons from the beam
C) Increasing the overall intensity of the beam
D) Increasing the number of photons in the beam
B
- Which of the following effects in x-ray production accounts for approximately 80% of the emitted radiation?
A) Photoelectric effect
B) Compton scatter
C) Bremsstrahlung
D) Fluorescence
C
- What happens to the energy of an x-ray photon as it undergoes bremsstrahlung radiation?
A) It gains energy
B) It loses energy
C) It remains unchanged
D) It is transformed into visible light
B
- What is the primary purpose of using an intensifying screen in x-ray imaging?
A) To increase patient exposure
B) To convert x-ray energy into visible light
C) To reduce film processing time
D) To focus the x-ray beam
B
- What is the primary effect of adding filtration to an x-ray beam?
A) Increases the number of photons
B) Decreases the effective energy of the beam
C) Removes low-energy photons and increases the beam’s effective energy
D) Reduces image contrast
C
- The linear attenuation coefficient (LAC) of a material is most dependent on which factor?
A) The wavelength of the radiation
B) The material’s density
C) The temperature of the material
D) The thickness of the material
B
- Which type of radiation occurs when an electron is deflected near the nucleus of an atom, losing kinetic energy in the form of a photon?
A) Compton scatter
B) Photoelectric effect
C) Bremsstrahlung
D) Rayleigh scattering
C
- Which of the following is a key characteristic of polychromatic radiation?
A) All photons have the same energy
B) It produces a spectrum of photon energies
C) It only consists of high-energy photons
D) It is monochromatic and highly filtered
B
- What is the role of the latent image in photographic film?
A) To convert photons into visible light
B) To represent the unprocessed image before development
C) To reduce the exposure time
D) To increase the number of silver halide grains
B
Which of the following is wrong ?
A) The actual focal spot is determined by the anode angle
B) The effective focal length (spot size) increases with the anode angle.
C) The spatial resolution is improved when the effective focal spot is small
The actual focal spot is determined by the anode angle
FALSE. The actual focal spot is the physical area on the anode where the electron beam strikes. Its size is determined by factors such as the electron beam diameter and the design of the x‐ray tube—not by the anode angle.
B) The effective focal length (spot size) increases with the anode angle.
TRUE. Effective focal spot size=Actual focal spot size×sin(θ)This means that as the anode angle θ increases, sin(θ) increases, so the effective focal spot size increases
C) The spatial resolution is improved when the effective focal spot is small
TRUE. smaller effective focal spot produces less geometric unsharpness (penumbra) on the image, leading to better spatial resolution.
What is the advantage of having a large focal spot on the anode ? (one wrong answer)
Allows greater tube output intensity
B) Allows short exposure times
C) There is no advantage.
Allows greater tube output intensity
A larger focal spot distributes the electron beam’s heat over a wider area on the anode. This helps to dissipate heat more effectively, allowing the tube to operate at higher currents (mA) and produce more X‐rays without overheating. Thus, greater tube output intensity is indeed an advantage.
B) Allows short exposure times
Short exposure times help reduce motion blur and improve image quality. This is also an advantage.
C) There is no advantage. FALSE. This statement is incorrect because, as explained, there are clear advantages to having a large focal spot in terms of heat management and enabling higher output and shorter exposure times.
1) Which of the following statements correctly describes the anode heel effect?
A. X-ray intensity is greater on the cathode side of the tube due to absorption of some photons in the anode.
B. X-ray intensity is greater on the anode side due to the angle of the anode.
C. The anode heel effect causes more X-ray photons to be produced at the anode side of the tube.
D. The anode heel effect refers to uneven electron production at the filament.
A
2) Reducing the anode angle…
A. Increases the effective focal spot
B. Reduces heat production in the anode
C. Increases the anode heel effect
D. Creates a larger x ray field
C. all others are opposite
3) Added filtration to a polychromatic x ray beam (which is false)…
A. Reduce patient dose
B. Reduce the average energy
C. Shrinks the x ray spectrum
D. Reduces the overall output of x rays
B is false, it increases the average energy of the beam
4) Which of the following is true regarding the effect of kVp and mAs modulation?
A. Increasing the mAs by 15% is the same as doubling the kVp
B. Increasing the mAs increases the number of electrons, as well as the average energy of the electrons
C. Increasing the kVp increases the average energy of the electrons, and therefore the energy of the x rays produced
D. Increasing the kVp improves image contrast in all scenarios, but has to be balanced with patient dose
C. (A is the opposite way round, B is true for kVp, mAs only increases quantity of electrons, D, increased kVp increases Compton scatter and reduces contrast)
Q1: In an x-ray generator, the use of alternating current (AC) instead of direct current (DC) is essential because:
A) AC allows for continuous electron flow between cathode and anode
B) AC enables the use of transformers for voltage modulation
C) DC would produce higher energy x-ray beams
D) AC minimizes voltage ripple in high-frequency generators
B
Q2: In an x-ray circuit, what determines the voltage transformation ratio in a step-up transformer?
A) The turns ratio between primary and secondary windings
B) The input power supplied to the circuit
C) The resistance of the transformer coil
D) The current flow in the secondary coil
A
Q3: According to the transformer equation, if the primary coil has 200 turns and the secondary coil has 4000 turns, and the input voltage is 220V, what is the output voltage?
A) 2200V
B) 4400V
C) 5500V
D) 8800V
B
Q4: What is the primary function of the filament circuit in an x-ray tube?
A) Control the energy of x-ray photons
B) Regulate the high-voltage supply to the anode
C) Generate and control the thermionic emission of electrons
D) Convert alternating current into direct current
C
Q5: Which semiconductor material is most commonly used in solid-state rectifiers within x-ray generators?
A) Copper
B) Silicon
C) Tungsten
D) Molybdenum
B
Q6: Compared to a single-phase generator, a three-phase generator improves x-ray production by:
A) Increasing the frequency of x-ray pulses per second
B) Reducing power consumption by the x-ray tube
C) Decreasing the efficiency of x-ray photon production
D) Increasing voltage ripple to enhance beam penetration
A
Q7: In capacitor discharge x-ray generators, what limits their clinical application?
A) The continuous decay of voltage during exposure
B) Their inability to provide high-voltage output
C) Excessive heat production in the x-ray tube
D) The requirement of three-phase power input
A
Q8: The falling load principle in x-ray generators is primarily used to:
A) Maximize mA while maintaining the shortest exposure time possible
B) Reduce the load on the anode by lowering the voltage output
C) Increase the duration of x-ray exposure to optimize image contrast
D) Maintain constant tube current throughout the exposure
A
Q9: In an automatic exposure control (AEC) system using an ionization chamber, what parameter is directly measured to terminate exposure?
A) Voltage applied across the x-ray tube
B) The electrical charge generated by ionized air molecules
C) The number of x-ray photons emitted by the tube
D) The density of the patient’s anatomy
B
Q10: A single-phase x-ray generator with a 100% voltage ripple produces a beam with:
A) The highest possible efficiency
B) A continuous and uniform photon energy output
C) Significant fluctuations in photon energy, reducing beam efficiency
D) The same radiation output as a high-frequency generator
C
- What causes the anode heel effect in X-ray tubes?
A) Uneven electron distribution at the cathode
B) Reflection of X-rays within the collimator
C) Increased kVp during exposure
D) X-ray beam attenuation by the target material
D
- How does a decrease in the anode angle affect the anode heel effect?
A) Reduces the anode heel effect by increasing focal spot size
B) Increases the anode heel effect by decreasing the effective focal spot size
C) Has no impact on the anode heel effect but increases heat dissipation
D) Increases the intensity of the X-ray beam
B
- An X-ray generator can produce 700 mA at 100 kVp for a 100 ms exposure. What is its power rating?
A) 70 kW
B) 7 kW
C) 700 kW
D) 7000 kW
A
- According to regulatory requirements, the misalignment between the light field and X-ray field should not exceed which value?
A) 1% of the Source-to-Image Distance (SID)
B) 2% of the SID
C) 5% of the SID
D) 10% of the SID
B
- Which of the following factors will decrease the maximum allowable exposure on a tube rating chart?
A) Increasing the focal spot size
B) Increasing the anode rotation speed
C) Using a smaller anode disk diameter
D) Using a larger anode angle
C
- For an exposure of 120 kVp, 400 mA, and 0.2 seconds using a three-phase generator, what is the total heat unit (HU) deposition?
A) 9,600 HU
B) 12,960 HU
C) 16,800 HU
D) 24,000 HU
B
- During continuous fluoroscopy at 80 kVp and 3 mA, how much heat (HU) is generated per second?
A) 80 HU
B) 240 HU
C) 800 HU
D) 2400 HU
B
- Which type of X-ray accounts for the majority of radiation produced in an X-ray tube?
A) Characteristic radiation
B) Compton scattering
C) Bremsstrahlung radiation
D) Photoelectric effect
C
Which of the following materials is suitable for the interspace material in an X- ray grid?
Lead
Air
Carbon fibre
Caesium iodide
C
Which of the below is the main limiting factor of parallel grids as opposed to focussed grids?
Grid cut-off
Increased mAs required
Increased patient dose
Reduced contrast
A. B and C are true for both types of grids. Grids generally improve contrast by increasing photoelectric effect
3) The use of grids…
Increases the probability of the photoelectric effect
Reduces Compton scatter hitting the detector
Increases bremsstrahlung interactions
Reduces patient dose
B. It can’t alter the interactions that have already occurred, bremsstrahlung occurs in the anode, grids require an increased mAs so generally the dose to the patient is increased.
4) Without a grid a chest xray requires 85kVp and 0.8 mAs. You decide to use a focussed grid with a grid factor of 5. What settings will be required?
17kVp, 0.4mAs
425kVp, 4mAs
85kVp, 4mAs
17kVp, 0.8mAs
C
5) Which of the following anatomical areas would benefit from the air gap technique most?
Canine carpus
Feline carpus
Canine skull
Canine thorax
D, would it make the skull blurry?
6) Which of the following would you change to magnify an x ray image?
Increase source to object distance
Increase source to film distance
Decrease source to object distance
Decrease source to film distance
C, (D)
7) What reaction happens at the fluorescent input screen and photocathode in an image intensifier as part of a fluoroscopy machine?
Light photons> electrons
Xrays>light photons>electrons
Electrons>light photons
Xrays>Electrons>light photons
B
Which factor most directly affects the spatial resolution of a digital image?
a) Field of View (FOV)
b) Number of pixels in the matrix
c) Bits per pixel
d) Image contrast
B
What is the recommended pixel matrix size for detecting objects smaller than 1 mm in fluoroscopic imaging with a 23 cm field of view?
a) 256 x 256
b) 512 x 512
c) 1,024 x 1,024
d) 2,048 x 2,048
C
What happens if pixel size is larger than half the size of the smallest object to be detected?
a) Image contrast improves
b) Image resolution decreases
c) File size decreases
d) Image intensity increases
B
Which component is primarily responsible for image processing and 3D image calculations in modern computers?
a) CPU
b) RAM
c) GPU
d) LAN Adapter
C
- What is the main advantage of increasing RAM in a computer system used for radiology imaging?
a) Faster image rendering
b) Improved network connectivity
c) Reduced image contrast
d) Increased storage capacity
A
Which of the following storage devices offers the fastest data access but lacks redundancy?
a) RAID Level 0
b) RAID Level 1
c) Magnetic Tape
d) DVD
A
- Which image format is preferred for maintaining high-quality medical images without compression loss?
a) JPEG
b) TIFF
c) PNG
d) BMP
B
- What is the key difference between indirect and direct digital radiography (DR) detectors?
Indirect DR converts X-rays directly into an electrical charge, while direct DR converts them into light first.
Indirect DR converts X-rays into light first, while direct DR converts them directly into an electrical charge.
Indirect DR uses selenium, while direct DR uses caesium iodide.
Indirect DR produces sharper images than direct DR.
B
- What is the primary function of a Thin-Film-Transistor (TFT) array detector?
a) Converts X-rays into visible light
b) Stores and amplifies the signal as an electrical charge
c) Directly converts X-rays into grayscale images
d) Controls the intensity of the X-ray beam
B
- What material is commonly used as the scintillator in indirect DR detectors?
a) Amorphous selenium (a-Se)
b) Silicon carbide
c) Caesium iodide (CsI:TI)
d) Lead oxide
C
- Why does direct DR provide high spatial resolution?
a) It eliminates light conversion, preventing lateral light spread.
b) It uses a thicker CsI layer to improve detection efficiency.
c) It scatters X-ray photons to sharpen the image.
d) It allows for larger pixels to capture more detail.
A
- Which of the following statements regarding Computed Radiography (CR) and X-ray luminescence is TRUE?
a) The latent image in a CR plate is formed by the direct deposition of silver halide crystals.
b) Europium (Eu²⁺) acts as a dopant in BaFBr phosphor and is oxidized to Eu³⁺ during X-ray exposure.
c) During image readout, a blue laser beam stimulates trapped electrons to emit red light photons.
d) The latent image in a CR plate is permanent and can be re-read multiple times without erasure
B
- What does the Fill Factor represent in an indirect TFT detector?
a) The total number of pixels in the detector
b) The X-ray absorption efficiency of the scintillator
c) The total area occupied by electronic components
d) The ratio of the sensitive area to the total area of a pixel
D
- What is a major drawback of CCD-based detectors compared to TFT detectors?
a) They are less expensive to manufacture
b) They have better radiation dose efficiency
c) They do not require an optical system
d) Optical minification causes light loss, increasing noise and reducing dose efficiency
D
- What is the main limitation of Digital Radiography (DR) when compared to film-screen radiography?
a) Lower contrast resolution
b) Lower spatial resolution
c) Inability to digitally enhance images
d) Inability to store images electronically
B
- Which of the following statements about Detective Quantum Efficiency (DQE) is TRUE?
a) A higher DQE means a higher radiation dose is required.
b) DQE measures how efficiently a detector converts incident X-rays into an image signal.
c) DQE is unrelated to image noise.
d) A lower DQE leads to better image quality.
B
- What type of noise occurs due to too few X-ray photons striking the detector?
a) Quantum noise
b) Electronic noise
c) Structured noise
d) Amplification noise
A
- What does Modulation Transfer Function (MTF) measure?
a) The system’s ability to convert X-rays into light
b) The efficiency of X-ray absorption
c) The ability to preserve contrast at different spatial frequencies
d) The number of pixels in an image
C
- Which statement about the H&D (Characteristic) curve is correct?
a) It is a linear relationship between exposure and optical density
b) It plots the log of relative exposure against optical density
c) It shows that optical density remains constant regardless of exposure
d) It is only relevant to digital radiography
B
- What happens in the toe region of the H&D curve?
a) High optical density, low transmittance
b) Best contrast and anatomical detail
c) Low optical density, high transmittance, minimal contrast
d) Maximum image contrast is achieved
C
- What does a steep characteristic curve indicate about the film’s latitude?
a) Wide latitude, suitable for thoracic radiographs
b) Narrow latitude, high contrast, suitable for bone X-rays
c) No effect on latitude, only exposure time
d) Increased exposure requirements and poor contrast
B
