X-Ray Imaging Techniques and Principles
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Questions and Answers

What is the primary purpose of reducing the penumbra in an X-ray image?

  • To increase patient comfort
  • To enhance image sharpness (correct)
  • To improve film processing
  • To minimize radiation exposure

    • Air appears white on X-ray film.

    False

    What type of film is used in dental X-rays?

    Non-screen film

    The width of the penumbra can be calculated using the formula 𝑝 = (D/L) * 𝑙, where 𝑝 is the penumbra width, D is the focal spot size, L is the _____, and 𝑙 is the object-film distance.

    <p>focal-object distance</p> Signup and view all the answers

    Match the following techniques with their purpose in improving X-ray image quality:

    <p>Using a small focal spot = Reduces penumbra width Positioning the patient close to the film = Increases image sharpness Using grids of lead and plastic = Reduces scattered radiation Holding breath during X-rays = Minimizes motion blur</p> Signup and view all the answers

    Which of the following is NOT a factor in increasing the sharpness of an X-ray image?

    <p>Large focal spot</p> Signup and view all the answers

    Dense bones allow more X-rays to pass through them compared to soft tissues.

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

    What is the term for the blurred edge of an object in an X-ray image?

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

    What is the primary function of a small focal spot in an X-ray tube?

    <p>It produces less image blurring.</p> Signup and view all the answers

    The line-focus principle aims to increase image blurring.

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

    What is emitted as a result of bremsstrahlung radiation?

    <p>X-ray photon</p> Signup and view all the answers

    Characteristic X-rays are emitted when an electron from an ____ shell fills a vacancy in the K-shell.

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

    Match the following types of X-rays with their descriptions:

    <p>Bremsstrahlung Spectrum = Continuous X-ray emission when electrons are decelerated Characteristic X-ray = X-ray produced when an outer electron fills a K-shell vacancy Small Focal Spot = Produces less image blurring, concentrates heat Large Focal Spot = More image blurring, dissipates heat over a larger area</p> Signup and view all the answers

    What characteristic of diagnostic X-rays is true?

    <p>They fall within the energy range of 15 to 150 keV.</p> Signup and view all the answers

    Increasing the kilovolt peak (kVp) raises the likelihood of electron penetration into the atomic nucleus.

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

    What effect does the temperature of the filament have on the X-ray tube?

    <p>It affects the number of electrons accelerated towards the anode.</p> Signup and view all the answers

    What is the primary purpose of using grids during X-ray imaging?

    <p>To reduce scatter radiation</p> Signup and view all the answers

    Motion during X-ray exposure can cause blurring in the images.

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

    What unit is used to measure X-ray radiation exposure?

    <p>roentgen (R)</p> Signup and view all the answers

    The exposure-area product (EAP) is calculated as exposure (roentgen) multiplied by ______ (cm²).

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

    Which of the following is a disadvantage of using grids in X-ray imaging?

    <p>They may absorb some primary beam photons</p> Signup and view all the answers

    Match the interaction type with its description:

    <p>Direct interaction = Radiation energy is transferred to DNA causing structural changes Indirect interaction = Radiation energy is absorbed by water molecules forming free radicals</p> Signup and view all the answers

    What materials are commonly used as filters in X-ray beam filtration?

    <p>Aluminum, copper</p> Signup and view all the answers

    High-energy x-rays increase patient radiation dose without improving diagnostic quality.

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

    What is the primary use of X-rays in medicine?

    <p>Diagnosis and radiotherapy</p> Signup and view all the answers

    X-rays belong to the same category as radio waves and visible light.

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

    What is the relationship between the energy of a photon and its frequency?

    <p>Directly proportional</p> Signup and view all the answers

    The main component of the X-ray tube that produces electrons is the ______.

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

    Match the components of X-ray production with their functions:

    <p>Cathode = Source of electrons Anode = Target for electron interaction Glass envelope = Allows electron acceleration High positive potential = Controls energy of electrons</p> Signup and view all the answers

    What percentage of the accelerated electron energy is converted to X-ray photons in the X-ray tube?

    <p>1%</p> Signup and view all the answers

    Increasing the atomic number of the anode material decreases the intensity of the X-ray beam.

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

    What is the melting point of tungsten, the material used for the anode in X-ray tubes?

    <p>3400 C°</p> Signup and view all the answers

    What is the energy equivalent of 1 keV?

    <p>Both A and B</p> Signup and view all the answers

    The power produced during an x-ray study is given in watts, calculated as P = I * V.

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

    What is the term for the thickness of material that reduces the intensity of radiation by half?

    <p>Half value thickness (HVT)</p> Signup and view all the answers

    The linear attenuation coefficient (μ) depends on the energy of x-rays, atomic number (Z), and ______.

    <p>density (ρ)</p> Signup and view all the answers

    Match the kVp values with their respective x-ray studies:

    <p>Mammography = 25 to 50 kVp Chest X-ray = ≈ 350 kVp</p> Signup and view all the answers

    Which of the following describes Bremsstrahlung?

    <p>A broad smooth curve in X-ray energy spectrum</p> Signup and view all the answers

    The intensity of an X-ray beam increases exponentially as it passes through matter.

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

    What happens during the photoelectric effect with X-rays?

    <p>Incoming X-ray photon transfers all energy to an electron, ionizing surrounding atoms.</p> Signup and view all the answers

    What are the two main categories of health effects from radiation?

    <p>Deterministic and Stochastic effects</p> Signup and view all the answers

    Stochastic effects of radiation can result in cancer development after a lag period of at least 5 years.

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

    What type of imaging technique is used for real-time visualization of patients?

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

    In tomography, a picture (graph) of a __________ is produced.

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

    Which imaging technique utilizes strong magnetic fields and radio waves?

    <p>Magnetic Resonance Imaging</p> Signup and view all the answers

    Match the following imaging techniques with their characteristics:

    <p>Fluoroscopy = Continuous acquisition of X-ray images CT Scan = Produces 3D images through multiple angles MRI = Uses magnetic resonance properties X-ray = Static images of structures</p> Signup and view all the answers

    The primary advantage of CT scans is their ability to display two-dimensional images of the body.

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

    What is the primary use of fluoroscopy?

    <p>Positioning catheters and visualizing contrast agents</p> Signup and view all the answers

    Study Notes

    X-ray Production and Types

    • X-rays are electromagnetic radiation with very short wavelengths, enabling high penetration power
    • X-rays are produced when energetic electrons interact with matter, converting kinetic energy into electromagnetic radiation
    • Main components of an X-ray tube include:
      • A source of electrons (cathode/filament)
      • An evacuated space (glass envelope)
      • A high positive potential (kV) to accelerate electrons
      • A target (anode) where electrons strike
    • The number of X-ray photons produced is controlled by tube current and time (mAs)
    • Energy of X-ray photons depends on frequency (E=hv=hc/λ) (h=Planck's constant, c=speed of light, λ=wavelength, υ=frequency)

    X-ray Interaction with Matter

    • Photoelectric effect (PE): High-Z elements, low energy photons. Photon energy is completely transferred to an electron. The electron leaves the atom, ionizing surrounding atoms. Bone absorbs X-rays much better than soft tissue because of PE (higher Z).
    • Compton scattering (CS): Low-Z elements, moderate energy photons. Only part of photon energy is transferred to the electron, and the remainder is scattered. More likely at higher energy levels (e.g., ≥30 keV in water/soft tissue). More likely than PE in bone at ≥100 keV
    • Pair production: High energy photons, rare occurrence. High energy photons convert into electron-positron pairs in the vicinity of the nucleus. Annihilation radiation produces two new photons.

    X-ray Image Quality

    • Penumbra: Blurred edge of an object in an X-ray image. Calculated by (P=D*L/l)
    • Focal spot size (D) and object to film distance (l) impact penumbra reduction. Ideally, smaller focal spots and larger object–image distances are preferred.
    • Grids: Reduce scatter radiation and improve image contrast by absorbing scattered rays before reaching the film. Thicker body parts produce more scatter radiation.
    • Contrast media: Iodine and barium-based compounds and air are used to highlight specific anatomical structures for better visualization.

    Fluoroscopy

    • Continuous acquisition of X-ray images over time (real-time). Useful for tracking motion (e.g., heart).
    • Uses X-ray detector systems to rapidly acquire images.

    Computed Tomography (CT)

    • Uses X-rays rotated around the body to create cross-sectional images.
    • Detects transmission data to provide detailed tomographic images.
    • 3-D slices remove superposition of anatomical structures.

    X-ray Exposure Units and Risks

    • Exposure is measured in roentgens (R).
    • Exposure-area product (EAP) considers both exposure and area for exposure calculations.
    • Radiation risk is associated with energy deposition in tissues. Deterministic effects follow high doses, resulting in immediate damage; stochastic effects follow low doses, potentially leading to cancer development.

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    Physics of Diagnostic X-Rays 2024-2025 PDF

    Description

    Test your knowledge on X-ray imaging techniques and principles. This quiz covers topics such as penumbra reduction, film types used in dental X-rays, and factors affecting image quality. Challenge yourself with questions that delve into the functions of focal spots and the types of X-rays.

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