Patient-Image Optimization in Radiography
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Questions and Answers

What does patient contrast primarily refer to in radiography?

  • The degree of differential absorption of x-rays by the tissues (correct)
  • The energy level of the x-ray beam used in imaging
  • The clarity of the image on the radiographic film
  • The positioning of the patient during the imaging process

    • Which body type is characterized by being small and frail?

  • Sthenic
  • Asthenic (correct)
  • Hypersthenic
  • Hyposthenic

    • How does patient thickness affect x-ray attenuation?

  • Thickness has no effect on x-ray attenuation
  • Thicker body sections cause more x-rays to scatter than absorb
  • Thicker body sections allow more x-rays to pass through
  • Thicker body sections attenuate more x-rays than thinner sections (correct)

    • What does the term 'attenuation' describe in the context of radiography?

    <p>The reduction in the number of x-ray photons after passing through material</p> Signup and view all the answers

    Which factor does NOT influence subject contrast in radiography?

    <p>Geometric positioning of the patient</p> Signup and view all the answers

    In the equation for radiographic contrast, what does IR contrast represent?

    <p>The average gradient of the radiographic film</p> Signup and view all the answers

    Which factor directly affects the number of x-rays exiting the body during radiography?

    <p>Tissue mass density</p> Signup and view all the answers

    Which of the following best describes the term 'subject contrast'?

    <p>It is influenced by the x-ray absorption characteristics of the subject</p> Signup and view all the answers

    At which wavelength is bright-light vision best?

    <p>555 nm</p> Signup and view all the answers

    Which unit is used to measure illuminance on a surface?

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

    What is the relationship between luminous intensity and distance according to the inverse square law?

    <p>Luminous intensity decreases in proportion to the inverse square of the distance</p> Signup and view all the answers

    What is the basic photometric unit that measures luminous flux?

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

    Which condition yields an illuminance of approximately 10,000 footcandles?

    <p>Sunny Day</p> Signup and view all the answers

    What is the measurement unit for luminance?

    <p>Candela per square meter</p> Signup and view all the answers

    How do laser printed images commonly appear to radiologists?

    <p>On a viewbox</p> Signup and view all the answers

    What phenomenon is explained by the cosine law in terms of luminous intensity?

    <p>Luminous intensity reduces illumination and contrast when viewed from the side</p> Signup and view all the answers

    What is the purpose of image inversion in digital imaging?

    <p>To make soft tissues appear black and bones white.</p> Signup and view all the answers

    Which post-processing technique is primarily used to correct for patient motion in a series of images?

    <p>Pixel Shift</p> Signup and view all the answers

    How does edge enhancement benefit digital imaging?

    <p>It highlights fractures and small, high-contrast tissues.</p> Signup and view all the answers

    What is the function of the 'Region of Interest' in digital imaging?

    <p>To compute the mean pixel value for a specific area.</p> Signup and view all the answers

    Which technique is utilized in Digital Subtraction Angiography (DSA) to improve visibility of certain areas in an image?

    <p>Image Subtraction</p> Signup and view all the answers

    What is a characteristic of skeletal imaging related to bone loss?

    <p>A 50% loss of bone is required before changes can be seen.</p> Signup and view all the answers

    Which pathology is indicated to potentially require an increase in radiographic technique due to fluid accumulation?

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

    Which of the following is NOT considered a destructive pathology?

    <p>Fractures (without gross swelling)</p> Signup and view all the answers

    What factor significantly influences the quality of a radiographic image?

    <p>Patient movement during imaging</p> Signup and view all the answers

    What role does the 'long scale contrast' play in respiratory imaging?

    <p>It helps to see lung processes clearly.</p> Signup and view all the answers

    Which of the following is true regarding multiple myeloma in the context of radiographic imaging?

    <p>It can cause osteolytic lesions which are visible.</p> Signup and view all the answers

    Which imaging quality factor is related to the ability to clearly image small objects?

    <p>Spatial Resolution</p> Signup and view all the answers

    What effect does aerophagia have on imaging techniques?

    <p>It requires an increase in imaging technique due to air accumulation.</p> Signup and view all the answers

    What is line noise in imaging?

    <p>Artifacts caused by voltage variations</p> Signup and view all the answers

    What should be done to correct a defective pixel?

    <p>Interpolate signals from adjacent pixels</p> Signup and view all the answers

    How does window width affect image contrast?

    <p>Increasing window width decreases contrast</p> Signup and view all the answers

    What is the primary purpose of dynamic range in imaging?

    <p>To expand the visibility of gray shades</p> Signup and view all the answers

    What is the maximum number of gray shades a 12-bit dynamic range can display?

    <p>4,096 shades</p> Signup and view all the answers

    Which post-processing method improves visibility and spatial resolution?

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

    Which action corresponds to increasing window level?

    <p>Increasing density</p> Signup and view all the answers

    What is the function of image inversion in post-processing?

    <p>To change white to black and vice versa</p> Signup and view all the answers

    Study Notes

    Patient-Image Optimization

    • Patient/Subject Factors: affect how x-rays are absorbed, influencing image quality.

      • Subject Contrast: Degree of differential absorption between tissues.
        • High subject contrast: Large difference in x-ray absorption, like bone and soft tissue.
        • Low subject contrast: Small difference in x-ray absorption, like different types of soft tissue.
      • Patient Thickness: Thicker sections attenuate more x-rays, affecting contrast.
      • Tissue Mass Density: Denser tissues (bone) absorb more x-rays than less dense tissues (lung).
      • Effective Atomic Number: Higher atomic numbers (bone) absorb more x-rays than lower atomic numbers (soft tissue).
      • Object Shape: Influences x-ray attenuation and contrast.

    • Image-Quality Factors: Influence the overall quality of a radiographic image.

      • Spatial Resolution: Ability to image small objects with high contrast.
      • Contrast Resolution: Ability to distinguish subtle differences in tissue density.
      • Distortion: Geometric distortion of the image due to misalignment.
      • IR Response: The response of the image receptor to the x-rays.

    Radiographic Quality

    • Radiographic contrast is influenced by both image receptor contrast and subject contrast.

    Body Types

    • Hypersthenic: Large frame, overweight.
    • Sthenic: Average, strong, active.
    • Hyposthenic: Thin, but healthy appearance.
    • Asthenic: Small, frail, emaciated.

    Pathologies

    • Destructive Pathologies: Often require a decrease in technique due to reduced tissue density.
      • Examples: Osteoporosis, Osteomalacia, Emaciation.
    • Non-Destructive Pathologies: Many diseases don’t significantly affect tissue density.
      • Examples: Fractures without swelling, Ulcers, Diverticula.

    Image Viewing and Quality

    • Pre-Processing: Corrections applied to the digital image before viewing.

      • Line Noise: Voltage variations in the image receptor are corrected.
      • Defective Pixel: Corrected by interpolating adjacent pixel signals.
      • Image Lag: Offset correction is applied to compensate for delayed pixel response.

    • Post-Processing: Changes to the image after it is acquired.

      • Annotation: Text labels are added to identify structures.
      • Window/Leveling: Adjust the brightness and contrast of the image.
        • Window Width: Controls contrast (more width = lower contrast).
        • Window Level: Controls brightness (higher level = brighter).
      • Magnification: Zooms in on a region of interest for better visualization of detail.
      • Image Flip: Re-orient the image vertically or horizontally.
      • Image Inversion: Reverses the black and white levels, improving visibility of certain features.
      • Subtraction: Removes portions of the image to enhance specific structures.
        • Used in DSA (Digital Subtraction Angiography).
      • Pixel Shift: Corrects for patient motion during a sequence of images.
      • Region of Interest: Calculates the mean pixel value in a specific area.

    Luminance and Image Viewing

    • Luminance Intensity: Brightness of the light source (viewbox or monitor).
      • Measured in units of candela per square meter.
    • Cosine Law: Viewing a monitor straight on provides the maximum luminance intensity.
      • Viewing from an angle reduces luminance intensity.
    • Inverse Square Law: Luminance intensity decreases inversely proportional to the square of the distance from the source.
    • LCD Monitors: Utilize a backlight to illuminate each pixel, creating the image.

    Digital Image Viewing

    • Hard Copy: Film based images viewed on a lightbox.
    • Soft Copy: Digital images viewed on a computer monitor.

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    Related Documents

    Patient Image Optimization & Viewing the Medical Image PDF

    Description

    This quiz explores the factors affecting patient-image optimization in radiography, focusing on x-ray absorption and image quality. Key topics include subject contrast, patient thickness, tissue density, and spatial resolution. Test your knowledge on how these variables influence radiographic images.

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