Radiation Dose in CT Imaging

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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?

Increasing mA for thicker tissue penetration Signup and view all the answers

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

20 to 40 mGy Signup and view all the answers

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

Allows for longer helical scans Signup and view all the answers

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

Linear attenuation coefficient Signup and view all the answers

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

4096 Signup and view all the answers

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

Slip-ring technology Signup and view all the answers

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

Table increment per rotation and beam collimation Signup and view all the answers

Which detector is commonly used in modern CT systems?

Solid-state scintillator detectors Signup and view all the answers

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

Increases contrast Signup and view all the answers

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

Extent of details contributing to the signal Signup and view all the answers

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

Interpolates into planar images Signup and view all the answers

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

Spatial resolution and image quality Signup and view all the answers

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

Determining the mean CT number of the nodule Signup and view all the answers

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

High SNR required for high contrast resolution Signup and view all the answers

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

Compton scattering Signup and view all the answers

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

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

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

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

Which factor influences the Collimator Pitch CTDIvol in CT imaging?

Collimation mm Signup and view all the answers

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

Decreases patient dose Signup and view all the answers

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

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

What parameter increases with tube voltage in CT imaging?

Image contrast Signup and view all the answers

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

Reduces dose Signup and view all the answers

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

Develop mA settings based on patient weight or diameter Signup and view all the answers