CT Review
The ability to display small objects, or define small objects distinctly describes? - correct answer
✔✔Spatial resolution
Tomography's root word "tomo" means? - correct answer ✔✔Cut, section, or layer
CT numbers are usually provided in the form of? - correct answer ✔✔Houndsfield units
The reduction in intensity of an x-ray beam as it interacts with matter is termed? - correct answer
✔✔attenuation
The most current and proper name for CT is? - correct answer ✔✔Computed Tomography
What is a major limitation of conventional radiography when compared to computed tomography?
-superimposition of tissues
-homogenous x-ray photon production
-increased radiation dose to the patient
-lack of digital imaging capabilities - correct answer ✔✔Superimposition of tissues
A CT scanner creates what type of images? - correct answer ✔✔cross-sectional
The thickness of a slice would be determined by what axis of the body? - correct answer ✔✔z-axis
Given the window setting of window width = 1200, and window level = -300, what would be the lowest
value in the range? - correct answer ✔✔-900
A ct image is displayed in a window with a level of 0 and a width of 500. What would the pixel values be?
- correct answer ✔✔pixels with values between -250 and +250 HU are assigned shades of grey
,RIO measurements include what?
-the area selected
-the average HU
-the standard deviation - correct answer ✔✔all of the above
As the displayed field of view decreases
1. less anatomy is selected
2. spatial resolution increases
3. spatial resolution decreases - correct answer ✔✔1 and 2
what CT number represents water? - correct answer ✔✔0
Window width represents what? - correct answer ✔✔image contrast
to view a CT image on a LCD monitor, data must undergo what? - correct answer ✔✔digital-to-analog
conversion
a 16 slice helical/spiral scanner produces how many images from a single slice of scan data? - correct
answer ✔✔16
what operation forms the basis for CT reconstruction? - correct answer ✔✔Fourier transform
how do we solve for mAs - correct answer ✔✔mA x time
what is a common kVp for pediatric patients? - correct answer ✔✔80 kVp
If we increase our matrix from 512 x 512 to 1024 x 1024, pixel size and spatial resolution do what? -
correct answer ✔✔pixel size decreases
spatial resolution increases
, Increasing our mA in CT allows us to do what? - correct answer ✔✔allows us to lower our scan time
Decreasing pixel size does what to the number of photons? - correct answer ✔✔decreases
Decreasing pixel size does what to noise? - correct answer ✔✔increases
Which matrix will have the most pixels?
a. 80x80
b. 256x256
c. 512x512
d. 1024x1024 - correct answer ✔✔1024x1024
How many pixels would a 1024x1024 matrix contain? - correct answer ✔✔1,048,576
When a matrix size is decreased from 1024^2 to 512^2 for the same field of view, which of the following
would be true?
1. the pixels will become larger
2. the pixels will become smaller
3. there will be a greater amount of volume averaging.
4. there will be less volume averaging - correct answer ✔✔1 and 3
A two dimensional square created by the x and y axis of the matrix is called - correct answer ✔✔picture
element
The z axis runs along what? - correct answer ✔✔the length of the body
The atomic number of an object or tissue and the amount of x-ray beam attenuated demonstrates what
type of relationship? - correct answer ✔✔direct
The ability to display small objects, or define small objects distinctly describes? - correct answer
✔✔Spatial resolution
Tomography's root word "tomo" means? - correct answer ✔✔Cut, section, or layer
CT numbers are usually provided in the form of? - correct answer ✔✔Houndsfield units
The reduction in intensity of an x-ray beam as it interacts with matter is termed? - correct answer
✔✔attenuation
The most current and proper name for CT is? - correct answer ✔✔Computed Tomography
What is a major limitation of conventional radiography when compared to computed tomography?
-superimposition of tissues
-homogenous x-ray photon production
-increased radiation dose to the patient
-lack of digital imaging capabilities - correct answer ✔✔Superimposition of tissues
A CT scanner creates what type of images? - correct answer ✔✔cross-sectional
The thickness of a slice would be determined by what axis of the body? - correct answer ✔✔z-axis
Given the window setting of window width = 1200, and window level = -300, what would be the lowest
value in the range? - correct answer ✔✔-900
A ct image is displayed in a window with a level of 0 and a width of 500. What would the pixel values be?
- correct answer ✔✔pixels with values between -250 and +250 HU are assigned shades of grey
,RIO measurements include what?
-the area selected
-the average HU
-the standard deviation - correct answer ✔✔all of the above
As the displayed field of view decreases
1. less anatomy is selected
2. spatial resolution increases
3. spatial resolution decreases - correct answer ✔✔1 and 2
what CT number represents water? - correct answer ✔✔0
Window width represents what? - correct answer ✔✔image contrast
to view a CT image on a LCD monitor, data must undergo what? - correct answer ✔✔digital-to-analog
conversion
a 16 slice helical/spiral scanner produces how many images from a single slice of scan data? - correct
answer ✔✔16
what operation forms the basis for CT reconstruction? - correct answer ✔✔Fourier transform
how do we solve for mAs - correct answer ✔✔mA x time
what is a common kVp for pediatric patients? - correct answer ✔✔80 kVp
If we increase our matrix from 512 x 512 to 1024 x 1024, pixel size and spatial resolution do what? -
correct answer ✔✔pixel size decreases
spatial resolution increases
, Increasing our mA in CT allows us to do what? - correct answer ✔✔allows us to lower our scan time
Decreasing pixel size does what to the number of photons? - correct answer ✔✔decreases
Decreasing pixel size does what to noise? - correct answer ✔✔increases
Which matrix will have the most pixels?
a. 80x80
b. 256x256
c. 512x512
d. 1024x1024 - correct answer ✔✔1024x1024
How many pixels would a 1024x1024 matrix contain? - correct answer ✔✔1,048,576
When a matrix size is decreased from 1024^2 to 512^2 for the same field of view, which of the following
would be true?
1. the pixels will become larger
2. the pixels will become smaller
3. there will be a greater amount of volume averaging.
4. there will be less volume averaging - correct answer ✔✔1 and 3
A two dimensional square created by the x and y axis of the matrix is called - correct answer ✔✔picture
element
The z axis runs along what? - correct answer ✔✔the length of the body
The atomic number of an object or tissue and the amount of x-ray beam attenuated demonstrates what
type of relationship? - correct answer ✔✔direct
