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Advanced Modalities
Computed Tomography
| Question | Answer |
|---|---|
| CT eliminates ____________ encountered in X-ray by passing a __________ __________ ________ through a part at many different __________. | Superimposition; Tightly collimated beam; Angles |
| CT creates a _________-__________ ___________ plane of any part of the body. | Cross-sectional tomographic |
| The CT scan is obtained by an __________ _________ rotating around a body part. | X-ray Tube |
| Exit ___________ is measured by a _____________ assembly. | Radiation; detector |
| The __________ assembly sends the measured __________ __________ information or ___________ data to the computer. | Detector; Exit Radiation; Primary |
| CT has improved ___________ resolution due to the reduction in ___________ radiation. | Contrast; scatter |
| The newest method of data acquisition from CT is __________/__________ CT. | Spiral/Helical |
| With Spiral/Helical CT the __________ rotates continuously while the table moves through the aperature at the same time. | Gantry |
| _________ _________ technology makes continuous rotation of the tube possible. | Slip-ring |
| __________ _________ forms a spiral path from which raw data is obtained. | Continuous motion |
| Multi-slice gathers _____ slices in ______ mS. | 4; 350 |
| The significance of Spiral/Helical CT is that it scans a ___________ of tissue rather than __________ _________. | Volume; Individual slices |
| 3 Advantages of Spiral/Helical CT: | 1)Respiratory motion is minimized; 2)Useful for detecting small lesions 3)Useful for noncooperative, combative, trauma and pediatric patients. |
| The technical aspects of CT is that it provides information on _________ relationships and ___________ characteristics. | Positional; Tissue |
| The radiation __________ measures exit radiation and coverts it to an _____________ ___________ and sends it to the computer. | Detector; Electronic signal |
| The Raw Data is the __________ __________ ______________ values. | Measured X-ray transmission |
| The computer ____________ the signal received which is actually assigning a ___________ _________ to each signal. | Digitizes; Whole number |
| The Matrix is an array of ___________ arranged in a ___________ of ________ and ________. | Numbers; Grid; Rows and columns |
| A _________ is a single square or picture element within a matrix. | Pixel |
| The __________ is the volume element of the digital image and matrix; It is the product of the __________ area and _________ ___________. | Voxel; Pixel and slice thickness |
| Each __________ represents a piece of anatomy and is displayed on the image monitor as a dot of light in one of the shades of gray. | Pixel |
| The __________ the pixel, the ____________ the piece of anatomy being represented and the better the __________ _________ __________ will be. | Smaller; Smaller; Image Quality Resolution |
| Each pixel is assigned a number that is related to the ___________ _____________ __________ of the tissue within each __________. | Linear Attenuation Coefficient; Voxel |
| The numbers assigned to each pixel are called ____ numbers or _____________ Units. | CT numbers or Hounsfield Units |
| Hounsfield numbers of tissue varies according to the ______________ of that tissue. | Density |
| More dense tissue have __________ numbers and less dense tissue have ___________ numbers. | Higher numbers; Lower numbers |
| Hounsfield numbers range between _____________ and _____________ and has recently been expanded to ____________ for bone imaging. | -1000 HU to +1000 HU; +4000 HU |
| The average Hounsfield units for the following: (1) Air; (2) Water; (3) Blood; (4)Muscle; (5) Bone | (1)Air: -1000; (2) Water: 0; (3) Blood: +20 to +50; (4) Muscle +35 to +50; (5) Bone: +150 to +1000 |
| Higher HU numbers appear ___________ and lower HU numbers appear ___________. | Lighter; Darker |
| ___________ determines the amount of data displayed on the monitor. | Field of View (FOV) |
| The _________ _________ and the _________________ determines the pixel size. | Matrix size; Displayed FOV |
| Pixel Size = _________/_________ | DFOV/Matrix Size |
| _____________ is the ability of an imaging system to differientiate among objects. | Resolution |
| ___________ is the reference material for CT because: (1) __________ in the body; (2) has ___________ __________; (3) and is assigned an arbitrary value of ___________. | Water; (1) Abundant; (2) Uniform Density; (3) Arbitrary value of 0 |
| __________ CT numbers are more dense than water and ___________ CT numbers are less dense than waater. | Positive; Negative |
| CT numbers scale range from __________ for air to ___________ for dense bone. | -1000; +14,000 |
| The __________ _________ on the display corresponds to the CT number for that pixel. | Gray level |
| __________ ____________ allows the technologist to alter the _________ of the displayed image by adjusting the window _______ and window _________. | Windowing Technique; Contrast; Level; Width |
| Windowing is ________-_______ mapping. | Gray-Level |
| The Window _________ is the range of CT numbers used to map signals into shades of gray and establishes the __________ of gray levels displayed. | Width; number |
| Narrow Window = _________ shades of gray and __________ contrast (or _______-scale contrast) | Fewer; Higher; Short-scale |
| A Wide Window = ___________ shades of gray and __________ contrast (or ________ scale contrast) | Greater; Lower; Long-scale |
| ___________ ___________ determines the midpoint of range of the gray range displayed. | Window Level |
| The Window Level should be set to the CT number of the __________ of interest. | tissue |
| The increments that the table moves through the gantry is termed ___________. | Indexing |
| Contrast Media is used to help distinguish _____________ anatomy from ___________ and increases the visibility of _____________ ______________. | Normal anatomy; Pathology; Disease Processes |
| Contrast media for CT may be administered: (1) (2) (3) | (1) IV; (2) Orally; (3) Rectally |
| MPR is ____________ ____________ and is the ability to reconstruct ___________ images into __________, __________, or ___________ body planes without additional radiation to the patient. | Multiplaner Recontruction; Axial; Sagittal; Coronal; Oblique |
| The initial introduction of _________ raised concerns that CT would become obsolete. | MRI |
| CT demonstrates _________ better than MRI. MRI demonstrates _____________ better than CT. | CT demonstrates bone better than MRI. MRI demonstrates Soft Tissue better than CT. |
Created by:
foster1317
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