Computed Tomography Ch 7 Exam 1 questions
& answers
similarities in Radiography and CT - answer x-ray passes through patient
and are absorbed in different ways by the body tissues
difference is radiography and CT - answer -Radiography: beam pass thru
the patient to the IR
-CT: beam passes through the patient as it circles around the patient
acquiring a cross sectional image
shortcoming of radiography - answer -all structure are superimposed
making it have to distinguish between structures
-difficulty to distinguish slightly different changes of issues
-proves to be a qualitative process rather and quantitative
Tomography - answer -move the tube and IR simultaneously in opp
directions
-allow unwanted sections the be blurred while desires sections stay
focued
-eliminate structures above and below focused section
, downside of tomography - answer -persistent image blurring
-degradation of image contrast
-problems resulting from film-screen combo
-failure to demonstrate small differences in tissue contrast
goals of CT - answer -eliminate the limitations of radiography
-those of superimposition
-improve contrast resolution
-record information accurately (very small difference in tissue contrast)
three steps to achieve goal of CT - answer 1)A carefully collimated beam
of x-rays is transmitted through a specific cross-section of the patient.
This removes superimposition above and below the desired slice.
2)Collimation serves multiple purposes. Eliminates superimposition,
Minimizes scatter which is degrading to the final image, Lowers Patient
Dose, Improves image contrast
3)Remaining photons hit the detectors and are measured which is
quantitative and can measure very small differences in tissue contrast.
The data from the detectors are processed by a digital computer that
uses special algorithms to reconstruct an image of the cross section.
three physical processes that occur in CT - answer 1. data acquisition:
get data
& answers
similarities in Radiography and CT - answer x-ray passes through patient
and are absorbed in different ways by the body tissues
difference is radiography and CT - answer -Radiography: beam pass thru
the patient to the IR
-CT: beam passes through the patient as it circles around the patient
acquiring a cross sectional image
shortcoming of radiography - answer -all structure are superimposed
making it have to distinguish between structures
-difficulty to distinguish slightly different changes of issues
-proves to be a qualitative process rather and quantitative
Tomography - answer -move the tube and IR simultaneously in opp
directions
-allow unwanted sections the be blurred while desires sections stay
focued
-eliminate structures above and below focused section
, downside of tomography - answer -persistent image blurring
-degradation of image contrast
-problems resulting from film-screen combo
-failure to demonstrate small differences in tissue contrast
goals of CT - answer -eliminate the limitations of radiography
-those of superimposition
-improve contrast resolution
-record information accurately (very small difference in tissue contrast)
three steps to achieve goal of CT - answer 1)A carefully collimated beam
of x-rays is transmitted through a specific cross-section of the patient.
This removes superimposition above and below the desired slice.
2)Collimation serves multiple purposes. Eliminates superimposition,
Minimizes scatter which is degrading to the final image, Lowers Patient
Dose, Improves image contrast
3)Remaining photons hit the detectors and are measured which is
quantitative and can measure very small differences in tissue contrast.
The data from the detectors are processed by a digital computer that
uses special algorithms to reconstruct an image of the cross section.
three physical processes that occur in CT - answer 1. data acquisition:
get data
