PRINCIPLES OF CT EXAM QUESTIONS
AND ANSWERS
The varying shads of grey displayed on a CT image are created by ____ of the x-ray
beam - Answer-attenuation
The amount of x-ray beam scattered or absorbed per unit thickness the material is
expressed as its - Answer-linear attenuation coefficient
Which of the following is the approximate beam attenuation capability per unit thickness
of water at 125 kvp - Answer-0.180 cm-1
Which of the following is the name given to a three dimensional volume of image data -
Answer-voxel
Which scan axis goes along the long axis of the part being scanned and determines the
thickness of the slices - Answer-z-axis
Which of the following is a numerical value use in CT to compare tissue densities on a
CT image where water is assigned a value of 0 - Answer-hounsfield units
What is the name given to objects that appear on images that are not actually present in
the body - Answer-artifact
Which of the following is a negative effect of acquiring images with thinker slices -
Answer-thicker slices decrease ability to visualize smaller objects
____ ____ is the effect of hiding a small object in a thick image slice by averaging the
tissue densities together - Answer-volume averaging
In which of the following modes of data acquisition does the table continue to move as
the scan is being acquired? - Answer-helical and spiral
____ data is the thousands of bits of data acquired by the CT during a procedure -
Answer-raw
Which criteria of image quality is defined by the speed of data acquisition - Answer-
spatial resolution
Which of the following CT parts permits continuous rotation of the CT unit during
acquisition - Answer-slip rings
What is unique shape of the filter used in CT imaging - Answer-bow tie
AND ANSWERS
The varying shads of grey displayed on a CT image are created by ____ of the x-ray
beam - Answer-attenuation
The amount of x-ray beam scattered or absorbed per unit thickness the material is
expressed as its - Answer-linear attenuation coefficient
Which of the following is the approximate beam attenuation capability per unit thickness
of water at 125 kvp - Answer-0.180 cm-1
Which of the following is the name given to a three dimensional volume of image data -
Answer-voxel
Which scan axis goes along the long axis of the part being scanned and determines the
thickness of the slices - Answer-z-axis
Which of the following is a numerical value use in CT to compare tissue densities on a
CT image where water is assigned a value of 0 - Answer-hounsfield units
What is the name given to objects that appear on images that are not actually present in
the body - Answer-artifact
Which of the following is a negative effect of acquiring images with thinker slices -
Answer-thicker slices decrease ability to visualize smaller objects
____ ____ is the effect of hiding a small object in a thick image slice by averaging the
tissue densities together - Answer-volume averaging
In which of the following modes of data acquisition does the table continue to move as
the scan is being acquired? - Answer-helical and spiral
____ data is the thousands of bits of data acquired by the CT during a procedure -
Answer-raw
Which criteria of image quality is defined by the speed of data acquisition - Answer-
spatial resolution
Which of the following CT parts permits continuous rotation of the CT unit during
acquisition - Answer-slip rings
What is unique shape of the filter used in CT imaging - Answer-bow tie
