S1_L2: Computed Tomography Scan Flashcards
TRUE OR FALSE: Denser structures are seen as darker shades of gray.
False
TRUE OR FALSE: One disadvantage of doing CT Myelogram is that allergic reactions may occur in patients sensitive to the contrast media.
True
TRUE OR FALSE: Modifying the window is a form of data conversion in the post processing stage of CT imaging.
True
TRUE OR FALSE: One advantage of CT scan imaging is that it is less time consuming than ultrasound.
True
TRUE OR FALSE: The x-ray tube is found inside the collimator assembly.
False
TRUE OR FALSE: Thinner CT slices for a tibial shaft fracture is recommended for adequate visualization of the extent of the fracture.
False
TRUE OR FALSE: Tumor is difficult to visualize in CT scan because tumors may have the same radiodensity as the surrounding structures even with the use of contrast media.
False
TRUE OR FALSE: Coronal images are viewed from back to front.
False
TRUE OR FALSE: Remnant radiation is the radiation that bounces off of the patient.
False
This individual discovered computed tomography in 1972.
Godfrey Hounsfield
Godfrey Hounsfield’s work was based on whose mathematical formulas for reconstruction of images for digital signals?
Alan Cornack
The first computed tomography scanners were dedicated for scanning and imaging of the ___.
brain/head
In 1976, whole body CT scans became possible. Godfrey Hounsfield was awarded the Nobel Prize in Medicine in 1979.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
Unlike x-rays, CT creates images based on cross-sectional (axial) slices, created by up to ____ projections from different angles.
1000
Enumerate the 3 elements of the CT scan
Gantry, operator’s console, and computers
Functional imaging is neuroimaging that demonstrates the microanatomy and macroanatomy of the brain. Structural imaging is neuroimaging that displays the activity of the brain based on metabolic activity.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
D. Both statements are false, terminologies were interchanged.
Note: The more metabolic activity (hyperactive area), the more the contrast media lightens up. However, all of it must normally light up in the same intensity.
A computed tomography scan creates images based on the radiodensity of tissues. Magnetic resonance imaging creates images based on the energy emitted from hydrogen protons in water or soft tissues.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
Element of the CT scan that transforms radiant energy to something we are able to see
Computers
Element of the CT scan that is CT technology used to control the scanning process, select slice thickness, reconstruction algorithms (post-processing), and other specifications.
Operator’s console
Element of the CT scan into which the patient slides during the examination
Gantry
- Imaged part can be rotated “in space” on the computer screen
- Acquires all the data in a single sweep of the scanner
A. Three-Dimensional CT
B. CT Myelogram
C. Cone Beam CT
- A
- C
- Used mostly in dentistry for TMJ
- Multiplanar reconstruction
- Invasive in nature, where a contrast media is injected into the subarachnoid space
A. Three-Dimensional CT
B. CT Myelogram
C. Cone Beam CT
- C
- A
- B
- For breast cancer detection as it is used for imaging of the breast
- Fallen out of favor d/t nature & with the advent of the MRI
A. Three-Dimensional CT
B. CT Myelogram
C. Cone Beam CT
- C
- B (MRI is more preferred as it is a non-invasive procedure)
Cone Beam CT uses a large, cone-shaped x-ray beam matched with a ____.
Flat-panel detector
TRUE OR FALSE: CT myelography is better able to distinguish between osteophytes, ligament infolding, and annular material than the MRI.
True
Source: Fundamentals of Musculoskeletal Imaging, 4th ed.
TRUE OR FALSE: Images captured using the three-dimensional CT is best viewed in digital format than on printed format.
True, it is easier to see the 3D image on the monitor in order to see the different angles of the particular area you are interested in.
TRUE OR FALSE: Cortical bone is more dense than cancellous bone.
True
E.g., The cranium is a flat bone with cancellous bone sandwiched between cortical bone.
For axial cuts/images, images are viewed in a ___ manner
caudo-cephalad
TRUE OR FALSE: For sagittal cuts, images are viewed from left to right for either side of the body.
True
CT scan slices are identified in terms of ____ that correspond to scout images.
slice numbers
It appears as a small locator image inserted into the left uppermost corner of the image for each slice.
Scout image
TRUE OR FALSE: Slice thickness for musculoskeletal CT can vary from 0.5 to 2 mm, for small joints, to 2 to 3 mm, for the pelvis.
True
Thinner slices are typically used in areas of rapidly changing anatomy. Smaller bones or joints can be missed in thicker slices.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
The ability to select the range of radiodensities displayed in an image.
Windowing
CT image made for the purpose of viewing musculature, soft tissues, or viscera.
Soft tissue window
CT image for viewing of the bone
Bone window
A brain image of the Circle of Willis looks like a ___.
star
To see the circle of willis in a CT scan, the slice is taken just above the ____.
Base of the skull
The eyes of the brain images Mr. Happy & Mr. Sad represent what structure?
anterior horns of the lateral ventricles
The smile/mouth of the brain image Mr. Happy represents what structure?
Quadrigeminal cistern
The frown (down-turned lips) of Mr. Sad represents what structure?
posterior horns of the lateral ventricles
The lateral ventricles are represented by what brain image?
(Back-to-Back) Worms
Each limb of the Cross brain image is made up what 2 structures?
Lesser wings of the sphenoid & petrosal portion of the temporal bone
TRUE OR FALSE: Gray matter is more dense than white matter.
True: it appears whiter due to its higher radiodensity, however, it is not as dense as bone.
To see the coffee beans brain image, the slice/cut must be taken almost at the ___ of the skull.
Vertex
The coffee beans brain image represents what structure?
Brain parenchyma
The temporal lobe is present in which cranial fossa?
Middle cranial fossa
Coronal slices offer the best view of the ventricular system. Sagittal slices best show the spinal cord, medulla, pons, and midbrain.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
It is the modality of choice for acute settings due to the short scanning times
Computed tomography
It is the most commonly used slice for diagnostic purposes
Axial slice
Case: A 56 y/o male pt was brought to the ER with signs of hydrocephalus and Arnold Chiari Type II malformation. Which CT slice is best to use for this patient?
A. Axial
B. Coronal
C. Sagittal
B. Coronal
Case: A 28 y/o male pt was brought in after sustaining a MVA head on collision. Which CT slice is best to use for this patient to detect any debris in the skull?
A. Axial
B. Coronal
C. Sagittal
C. Sagittal
Aperture that creates a narrow fan-shaped beam of x-rays and through which x-rays pass.
Collimator Assembly
Device that controls the radiation center
and determines the slice thickness of the CT scan.
Collimator Assembly
Device that measures remnant radiation, it is found opposite the x-ray tube.
Detector array
Note: Up to 1,000 detectors are arranged in an array, encircling the patient.
It amplifies the signal from the detectors in the form of varying electrical current, known as the analog signal. This signal will later on be converted into digital for an image to be seen in the computer.
A. X-ray tube
B. Detector Array
C. Data Acquisition
D. Collimator Assembly
C. Data Acquisition
It is the best imaging for evaluation of loose bodies in a joint.
Computed tomography scan
TRUE OR FALSE: CT is the modality of choice for detailed imaging of cortical and trabecular bone.
True
Source: Fundamentals of Musculoskeletal Imaging
It is an indirect imaging of the brain that demonstrates blood vessels in and around the brain.
A. Computed tomography
B. Cerebral angiography
C. Magnetic resonance imaging
D. Ventriculography
B. Cerebral angiography
An invasive, indirect imaging of the brain performed by injecting air in the ventricular system.
A. Computed tomography
B. Cerebral angiography
C. Magnetic resonance imaging
D. Ventriculography
D. Ventriculography
Note: It can be used in cases of patients with hydrocephalus.
TRUE OR FALSE: The scout image is a 3 dimensional digital radiograph, showing the localization of the structures to be scanned.
False, it is a 2 dimensional digital radiograph
TRUE OR FALSE: The screening process is where transduction occurs.
True
Sagittal or coronal cuts are performed to visualize the image that is created by the CT.
A. Matrix
B. Image
C. Post Processing
B. Image
The matrix becomes an image using a mathematical process known as ____.
back projection
The result is manipulated in the computer’s software to improve contrast and modify the window.
A. Matrix
B. Image
C. Post Processing
C. Post Processing
In data conversion, radiodensities are converted by the computer into a ____.
matrix
Additional: Each cell of the matrix is a pixel (picture element). Each pixel is assigned a shade of gray, which represents the radiodensity of that cell of the matrix, expressed in terms of Hounsfield units.
In viewing CT images, tissues have differing radiodensities represented by different shades of ____.
gray
In the CT, ____ structures are represented by white or a light shade of gray.
dense
Note: Less dense structures are darker.
A limitation of the CT scan is low radiation exposure. It also has a limited capability for determining the histological make up of tissues.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
B. Only the 2nd statement is true
It identifies blood clots or thrombosis, and hemorrhage. The point of occlusion associated with stroke can also be seen.
A. Computed tomography
B. Cerebral angiography
C. Magnetic resonance imaging
D. Ventriculography
B. Cerebral angiography
Note: When haziness is seen due to the contrast media leaking in the brain, this represents a hemorrhagic stroke.
Standard thickness for CT axial slices
2-3 mm
Note: 0.5mm is used for smaller images
Neuroimaging used for diagnosis of lesions that are too small to be detected.
Functional imaging
TRUE OR FALSE: CT scan has the same imaging principles as conventional radiography, where x-rays are attenuated by body tissues.
True
CT scans provide accurate measurement of osseous alignment. CT scans are less expensive than MRI and less problematic for claustrophobic patients.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
CT scan is more time consuming than MRI or UTZ. UTZ is fast but operator-dependent; without an US specialist, you won’t be able to do it.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
B. Only the 2nd statement is true
CT scan is not used for subtle fractures, complex fractures, and comminuted fractures. Instead, CT scan is used for IV disc conditions when combined with diskograms.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
B. Only the 2nd statement is true
In the 1970s, CT was used with nuclear medicine. In the 1980s, radioactively labeled chemicals were used for functional imaging of the brain.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
B. Only the 2nd statement is true
1970s: CT scan was used for neuroimaging.
1980s: CT & nuclear medicine, single-photon emission CT, & positron emission tomography.
CT scan is used to detect degenerative changes, spinal arthritic changes, and spinal stenosis especially with CT myelography. It can also be used for serious trauma, as multiple injuries to both osseous and soft tissue structures can be determined.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
During CT scanning, the x-ray tube revolves circumferentially (360º) around the patient in the gantry to get a slice. Then, it stops and the table is moved for a new slice, known as the stop-and-go action.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
Note: Movement of the tabletop is referred to in terms of pitch.
The x-ray tube and the high-voltage generator can be found in the ____.
Gantry
TRUE OR FALSE: Modern scanners move and scan continuously during the examination process, thus creating helical slices.
True
Duration of CT scan
~10 mins, which is why it is used for acute cases
