Radiation Dose in CT Imaging
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Questions and Answers

What is the equivalent number of chest x-rays with a CT Abdomen or Pelvis scan?

  • 35
  • 500 (correct)
  • 50
  • 400
  • Which organ receives the highest radiation dose during a Pelvis CT scan?

  • Uterus (correct)
  • Thyroid
  • Gonads
  • Eye lens
  • What is the induction of erythema typically caused by in terms of Gy?

  • 8 Gy
  • 2 Gy (correct)
  • 40 mGy
  • 26 mGy
  • How does modern CT scanners modulate the mA during the scan?

    <p>Increasing mA for thicker tissue penetration</p> Signup and view all the answers

    What is the typical range of patient skin doses in CT scans?

    <p>20 to 40 mGy</p> Signup and view all the answers

    If the mAs is reduced to half with no other changes, what effect does this have?

    <p>Allows for longer helical scans</p> Signup and view all the answers

    What aspect of tissue influences Compton scatter and plays a dominant role in forming contrast in medical CT?

    <p>Linear attenuation coefficient</p> Signup and view all the answers

    How many shades are utilized in the gray-scale of CT image voxels?

    <p>4096</p> Signup and view all the answers

    What technological advancement led to helical (spiral) acquisition in CT imaging?

    <p>Slip-ring technology</p> Signup and view all the answers

    In helical CT scanning, what does the pitch parameter indicate?

    <p>Table increment per rotation and beam collimation</p> Signup and view all the answers

    Which detector is commonly used in modern CT systems?

    <p>Solid-state scintillator detectors</p> Signup and view all the answers

    How does a narrower window width affect the contrast of a CT image?

    <p>Increases contrast</p> Signup and view all the answers

    What does the slice sensitivity profile describe in single slice CT?

    <p>Extent of details contributing to the signal</p> Signup and view all the answers

    How does helical data set interpolation compensate for differences in CT reconstruction algorithms?

    <p>Interpolates into planar images</p> Signup and view all the answers

    What does the choice of CT reconstruction kernel or algorithm chosen by the operator affect?

    <p>Spatial resolution and image quality</p> Signup and view all the answers

    What is the role of CT numbers in determining the amount of calcification in pulmonary nodules?

    <p>Determining the mean CT number of the nodule</p> Signup and view all the answers

    Which aspect of radiation dose in CT is unique compared to chest radiography?

    <p>High SNR required for high contrast resolution</p> Signup and view all the answers

    What is the principal interaction mechanism in CT that contributes to a considerable radiation dose from scattered radiation?

    <p>Compton scattering</p> Signup and view all the answers

    What does the Multiple Scan Average Dose (MSAD) in CT measure?

    <p>Average dose resulting from a large series of CT slices</p> Signup and view all the answers

    How is the Computed Tomography Dose Index (CTDI) measured?

    <p>Using a pencil-type ionization chamber in phantoms simulating heads and bodies</p> Signup and view all the answers

    Which factor influences the Collimator Pitch CTDIvol in CT imaging?

    <p>Collimation mm</p> Signup and view all the answers

    What is the impact of increasing pitch while holding other factors constant in CT scanning?

    <p>Decreases patient dose</p> Signup and view all the answers

    In which body scans are CTDI values typically lower and why?

    <p>Body scans, due to greater x-ray attenuation</p> Signup and view all the answers

    What parameter increases with tube voltage in CT imaging?

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

    What does decreasing kVp do to dose in CT imaging with other factors constant?

    <p>Reduces dose</p> Signup and view all the answers

    What is an effective way to reduce patient radiation dose in pediatric patients during CT scans?

    <p>Develop mA settings based on patient weight or diameter</p> Signup and view all the answers

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