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299 Cards in this Set

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Tungsten is used as the target material on the tubes anode because it has a (high/low) atomic number & a (high/low) melting point.

HIGH & HIGH
What scanner design was the first to acquire four slices in a single rotation?
Multi-Row Detector

The enormous heat that builds up in the CT tube is caused by the:

collision of electron beam w the tungsten target on the tube anode
The number of electrons that flow from the cathode to the anode in the tube is controlled by:
mA

The slip ring on continuous rotation CT scanners:
1. Prevents the high voltage cable from winding up.
2. Allows the exam to commence more rapidly.
3. Eliminates the need for the reversal of gantry frame rotation.

ALL (1,2,3)

Which of the following is NOT part of the CT tube?
1. Tungsten Target
2. Collimator
3. Rotating anode
4. Filament

2. Collimator
Which of the following are NOT commonly used on today's scanners?
1. Xenon detectors
2. 4th generation technology
3. Continuous rotation technology
1 & 2

Which system component converts the projection attenuation data into the proper digital form for the array processor?
1. Detector
2. Photodiode
3. ADC (analog to digital converter)
4. Host computer

3. ADC
X-ray photons are produced by a fast moving electron:
1. Colliding w an atomic nucleus
2. Passing close to a nucleus
3. Colliding w an electron w/in an atom and ejecting it.
ALL (1,2,3)
Which of the following is TRUE regarding solid state detectors?
1. Xray photons cause detectors to generate a flash.
2. Detector type used on most scanners
3. Used in both 3rd generation & 4th generation
ALL (1,2,3)

CT is commonly referred to as: (3)

Computerized Axial Tomography, CAT-Scan, & Computed Tomography
What control does the operator have over the x-rays in a CT exam?
Energy level & quantity of x-rays can be selected.
(TRUE or FALSE) kV is the voltage potential between the tube cathode & anode while mA controls the filament current.
TRUE

(TRUE or FALSE) kV controls the energy level of the x-ray photons & mA controls the number of x-ray photons emitted from the tube.

TRUE
Which of the following does NOT affect the quantity of x-rays that completely penetrates the pt?
1. The distance that the x-ray photons must travel on their course through the pt's body.
2. The molecular composition of the tissues through which the x-ray photons pass.
3. The type of detector material used.
3. The type of detector material used.
_______ made helical imaging possible.
1. Multi-Row Detector Scanners
2. 2nd Generation Technology
3. 4th Generation Technology
4. Continuous Rotation Scanners
4. Continuous Rotation Scanners

(TRUE or FALSE) The reconstruction process used to create the image occurs in the array processor.

TRUE
(TRUE or FALSE) To collect the complete set of CT data, x-rays must be passed through the body at many different angles.
TRUE
(TRUE or FALSE) The detectors measure x-rays which completely penetrate the pt.
TRUE
Which of the following is a component NOT normally located in the gantry of the CT?
1. Pre-Pt collimators
2. Solid State Detectors
3. Array Processor
4. X-ray tube
3. Array Processor
(TRUE or FALSE) X-rays are used in CT bc they penetrate the body according to specific attenuation characteristics of each tissue.
TRUE
X-rays are produced whenever fast moving electrons collide with any form of matter because:
the electron loses kinetic energy which is converted into the emission of an x-ray photon.
Brief description of how Bremsstrahlung Radiation occurs:
Incoming electron loses some kinetic energy which is converted into an x-ray photon under 2 conditions:
1. electron collides w nucleus
2. electron slowed down as it passes the nucleus
The mA determines the:
Quantity of x-ray photons
If you INCREASE ____ it will INCREASE the likelihood that a given x-ray will penetrate a material.
kV (penetrates)
What is accomplished by electrically blocking x-rays?
Collimation
(TRUE or FALSE) Scatter radiation is caused by deflections from the original trajectory of an x-ray photon through the pt.
TRUE
Which technology do Multi-Row Detector scanners employ?
1. 2nd Generation
2. 3rd Generation
3. 4th Generation
4. 1st Generation
2. 3rd Generation
(TRUE or FALSE) PACS system is used for long term data storage, digital distribution of images, & image display for the radiologist.
TRUE
(TRUE or FALSE) Regarding the MDCT, the size of the detector arrays along the z-direction may be different.
TRUE
(TRUE or FALSE) Regarding MDCT, the attenuation info from adjacent detector arrays may be added together to generate thicker slices.
TRUE
(TRUE or FALSE) Regarding the MDCT, all of the detector arrays may or may not be used.
TRUE
Most commands from the technologist are received by the:
Operator's Console
Which of the following CT scanner designs does NOT use an x-ray tube?
1. 1st Generation CT
2. PET/CT
3. Electron Beam CT
4. MDCT
3. Electron Beam CT
The time between the end of one scan and the start of the next scan during which the tube will cool refers to:
Interscan Delay Time
On a Single Row Detector Scanner, collimation:
1. Controls the slice thickness
2. Minimizes the x-ray dose to pt
3. Reduces the detection of scatter radiation
ALL (1, 2, 3)
What is the main purpose of the detector?
capture x-ray photons & convert them to a measurable signal.
(TRUE or FALSE) In order for an x-ray photon to be measured it must: enter the detector chamber, be absorbed by the detector material, & be converted to a measurable event.
TRUE
(TRUE or FALSE) The pt table may move continuously during the scan.
TRUE
The CT x-ray tube rotates around the pt to:
1. keep the tube cool
2. generate projection views at different angles
3. minimize the x-ray dose administered to the pt
2. generate projection views at different angles
(TRUE or FALSE) The cathode filament helps determine the size of the focal spot.
TRUE
System Components: Pt info, Imaging parameters, post processing techniques, filming & archiving is entered at:
Console
System Components: What dose the Host Computer do?
translates info into system language
System Components: What is responsible for timing & operation of the table, gantry, & high voltage generator?
Scan Controller
System Components: What is necessary to produce high voltage potential that exists between the cathode & anode?
High Voltage Generator
System Components: What does the Gantry include?
X-ray tube & Detectors
System Components: X-rays pass through the pt then measured by detectors then converted into tiny signals which are passed on to ________ which increases the tiny signals strength.
Amplifier
System Components: Analog signals are then sent to:
S/H
What generation scanner:
* Pencil Beam
* Single Detector
* Tube & Detector move
* Translate - Rotate
1st Generation
What generation?
* Fan Beam
* Multiple detectors
* Translate - Rotate
2nd Generation
What generation?
* Most scanners today
*Fan Beam
* Multiple Detectors
* Rotates
3rd generation
What generation?
* Fan beam
* Rotates
* Detectors all the way around gantry
* Only TUBE rotates around pt
4th generation
What type of scanner has no x-ray tube, an array of tungsten anodes, no moving parts and the imaging is good for the heart and coronary arteries?
Electron Beam CT
What are the (2) most common types of scans to FUSE?
CT & PET
Pt Coordinates:
X
Y
Z
X: LT to RT
Y: Anterior to Posterior
Z: Head to Feet
Tube Current =
mA
Tube Voltage =
kV
What are (2) types of collimation?
Pre & Post pt collimation
(Pre or Post Collimation) Restricts x-ray beam after it exits CT tube & before x-rays enter pt's body?
Pre pt collimation
(Pre or Post Collimation) Restricts unwanted x-rays from entering detectors from arbitrary angles.
Post pt collimation
What type of detectors are used today on most scanners?
Solid State Detectors
(TRUE or FALSE) When a photon strikes the solid state material it emits a flash of light which is converted into an electrical impulse by a photodiode.
TRUE
Using a _______ reconstruction filter would decrease the appearance of noise in a CT image.
Smooth
A ______ scan uses only a single projection.
Localizer
(TRUE or FALSE) Helical image data is well suited for 3D SSD because there is minimal misregistration or gaps.
TRUE
How is the 3D SSD generated?
stacking up contiguous transverse slices
(TRUE or FALSE) Pt motion during the scan is detrimental to the quality of the 3D images.
TRUE
Which type of storage media may hold CT image data?
1. Internal Hard Disk
2. CD
3. Re-writable optical disk
ALL (1, 2, 3)
______ may have to be edited from the data set to get a diagnostic MIP of a CTA exam.
1. Iodinated Contrast
2. Vessels of interest
3. Air
4. Bones
4. Bones
What are (3) advantages of a Helical Study?
* Minimal anatomical misregistration sometimes caused by inconsistent breath-holding.
* Shorter exam time
* Can retrospectively reconstruct a slice at any arbitrary position.
Which of the following utilizes convolution?
1. 3D SSD
2. Fourier Transform
3. Filtered Back Projection
3. Filtered Back Projection
What is the process of applying a filter to the raw data during the image reconstruction calculation?
Convolution
Which technique defines the surface on which to reconstruct by setting a threshold based on the CT number of the surface of interest?
1. VR
2. MPR
3. MIP
4. 3D SSD
4. 3D SSD
From which of the following can the most diagnostic multi-planar reconstructions be generated?
1. Stacked transverse images from a helical scan.
2. Stacked transverse images from a conventional, serial scan.
3. Stacked localizer images.
1. Stacked transverse images from a helical scan.
The actual attenuation data measured by the detectors from all projections during a scan is contained in CT _____ data.
1. Image
2. Convolved
3. Raw
3. Raw
(TRUE or FALSE) On a single-row detector scanner, the thickness is equal to the beam collimation.
TRUE
A retrospective reconstruction in which the reconstruction field of view is varied uses:
1. A reconstructed image in the sagittal plane.
2. CT raw data
3. More photons
4. CT image data
2. CT raw data
(TRUE or FALSE) The amplified electrical signal obtained from the detectors must be digitized.
TRUE
(TRUE or FALSE) Digital CT images are numerical representations of cross sectional anatomy.
TRUE
(TRUE or FALSE) Digital signals may be formed by sampling analog signals at discrete time intervals.
TRUE
What is the mathematical process used by single row detector scanners to reconstruct CT images from raw data?
Filtered Back Projection
What is a post processing technique which is always applied to reconstructed data rather than unprocessed data?
3D SSD
Define Pixel:
single 2D picture element
The pencil thin section of the x-ray fan beam that strikes a single detector is called a:
Ray
Define Kernel:
Filter applied to CT raw data
CTA images come from what type of scan?
Helical
If an image matrix has 360 rows & 360 columns, how many pixels are there in the image?
Explanation:

Pixels are a 2D picture element with in a matrix.

ANS> 360x360= 129,600
What determines the intensity of the laser beam in a laser camera?
pixel values
Which of the following is a reconstruction technique applied to the raw data after the primary reconstruction has already been accomplished?
1. Maximum Intensity Projection
2. Volume Rendering
3. Retrospective Reconstruction
4. Multi-Planar Reconstruction
3. Retrospective Reconstruction
What does convolution do to the image quality when it is added to the back projection reconstruction process?
Enhances important characteristics of attenuation profiles thus reducing streak and star artifacts
Which of the following may occur during the interscan delay of a conventional CT scan performed on a continuous rotation scanner?
1. The table position is incremented
2. The tube continues to rotate in the same direction as during the scan
3. The tube assembly makes a 360* rotation
ALL (1, 2, 3)
______ allows helical data to be converted into planar raw data.
Interpolation (mathematical step)
What is the most common type of film used for recording CT images?
Single emulsion
A helical scan performed on a 64 slice MDCT scanner is reconstructed with:
Cone Beam Reconstruction
______ yields an image that appears 3D but also shows anatomical details above & below the 3D surfaces.
VR
(TRUE or FALSE) MDCT scanners capable of collecting 64 slices in a single rotation do NOT use filtered back projection as their method of image reconstruction.
TRUE
MPR's are performed on which of the following?
1. Image data
2. Raw data
3. Attenuation profiles
Image data
The ______ moves during a helical scan on a 3rd generation scanner.
1. X-ray Tube
2. Pt table
3. Detector elements
ALL (1, 2, 3)
A CT system manufactureer has a scanner in which the focal spot of the x-ray beam can move to two, slightly separated, distinct locations. What benefit does the dual focal spot provide compared to an identical scanner possessing a single focal spot?
The number of projections is doubled
A smooth reconstruction filter is typically NOT selected for a _____ exam.
1. pituitary
2. kidneys
3. liver
4. IACs
4. IACs
In a ____, the highest pixel values from a stack of CTA images are projected along many rays.
1. SSD
2. MIP
3. PR
4. VR
2. MIP
The x-ray beam used in CT scanning is ______ the pt's tissues.
attenuated by
_________ is a calculation used for reconstructing the final CT images from the raw data by adding together the attenuation information collected from all the projections.
Back Projection
What are the (2) basic types of reconstruction filters?
Sharp & Smooth
What filter improves edges?
Sharp
What filter minimizes grainy or noise from an image?
Smooth
(TRUE or FALSE) Convolution to raw data then filtered back projection if not the image will have blurry edges and will be grainy.
TRUE
Cone Beam artifact causes what kind of appearance?
Spoke or Star like
Which of the following are possible results of partial voluming?
1. Decreased sharpness of edges.
2. Misleading CT numbers
3. Improvement in resolution
1. Decreased sharpness of edges.
2. Misleading CT numbers
Which of the following has the highest pt dose assuming all other parameters are the same?
1. mA=200, rotation time=2s
2. mA=200, rotation time=1s
3. mA=150, rotation time=3s
4. mA=400, rotation time=1s
3. mA=150, rotation time=3

mA x time = mAs
CT numbers _______ would appear black if a window width of 400 and a window level of -100 are used.
1. above +200
2. below -300
3. below -200
4. above +100
2. below -300
If a calcification with a CT number of +300 appears pure white on an image, which of the following could be the window width and window level selected?
1. WL= 0, WW= 500
2. WL= +300, WW= 500
3. WL= +100, WW= 1000
1. WL=0, WW= 500
Which of the following determinants of CT image quality is responsible for how grainy or speckled a CT image appears?
1. Resolution
2. Linearity
3. Noise
4. Contrast
3. Noise
(TRUE or FALSE) Magnification uses image data ONLY, NOT raw data.
TRUE
(TRUE or FALSE) Magnification will make the image appear enlarged but there is no change in the spatial resolution.
TRUE
If a thin slice is used, which of the following would help reduce the apparent image noise?
1. Reduced reconstruction field of view
2. Increased matrix
3. Increased mAs
4. Increased kVp
3. Increased mAs
A CT number calibration test should be performed:
daily
(TRUE or FALSE) As the ptich is increased, the helical path of the x-ray beam is stretched & a greater volume of anatomy can be covered in a given time.
TRUE
(TRUE or FALSE) Image spatial resolution is dependent upon the reconstruction FOV & image matrix
TRUE
An increase in ______ will result in hardening of an x-ray beam.
1. Tissue Density
2. Tissue Thickness
3. kVp
ALL (1, 2, 3)
If the slice thickness is changed from 5mm to 7mm and all other parameters are held constant, _____% more photons will be used in making the slice.
2mm difference

2/5= .4 x 100% = 40%
One dimension of a voxel is determined by:
slice thickness
If a reconstruction FOV of 32cm & a 512 x 512 matrix are used, the pixel size is:
Pixel size = reconstruction FOV / matrix

Pixel size = 32/512
Pixel size = .625
Decreasing Reconstruction FOV, (Increases/Decreases) pixel size.
Decreases pixel size
Decreasing Reconstruction FOV, (Increases/Decreases) spatial resolution.
Increases spatial resolution
Decreasing Reconstruction FOV, (Increases/Decreases) image noise.
Increases noise
What is the conversion equation from CT number to Hounsfield unit?
CT number = Hounsfield Unit
What is the total pixels in a 1024 x 1024 matrix.
more than a million
Reducing slice thickness, (Increases/Decreases) total number of photons, which (Increase/Decreases) the image noise.
Decreases photons, which Increases noise
Define Partial Volume Averaging:
different tissues w/in voxel are averaged together to yield a single CT number assigned to the pixel
Increase pitch, (Increase/Decrease) pt dose.
Decrease pt dose
Increase mAs, (Increase/Decrease) pt dose.
Increase pt dose
Increase table increment, (Increase/Decrease) pt dose.
Decrease pt dose
_______ affects the CT number of water.
1. No imaging parameter
2. The slice thickness
3. kVp
4. mAs
1. No imaging parameter
The smallest object that can be resolved if a reconstruction FOV of 24cm and a 512 x 512 matrix are used is _____mm.
24cm = 240mm (to change cm to mm just move the decimal one place over to the right)

240mm/512= 0.47
If the radiologist requires 2mm thick contiguous slices through the pituitary, and 2.4cm of coverage, ____ slices are necessary.
2.4cm = 24mm

24mm/2mm= 12
Decrease reconstruction FOV, (Increases/Decreases) spatial resolution.
Increases spatial resolution
Decrease reconstruction FOV, (Increases/Decreases) image noise
Increases image noise
What parameter affects the contrast of a CT image?
kVp (penetration/contrast)
What parameter is responsible for partial volume averaging?
Slice thickness
On MDCT, the final reconstructed slice thickness is determined by the:
the size of the detectors & how may of them combine their attenuation data
On a Single Row detector scanner what determines the final slice thickness?
the collimation of the x-ray beam.
The distance that the table travels between slices is called:
table increment
(TRUE or FALSE) The number of x-ray photons leaving the x-ray tube is directly proportional to mAs.
TRUE
(TRUE or FALSE) X-ray tube heating is directly proportional to mAs.
TRUE
(TRUE or FALSE) Radiation dose to the pt is directly proportional to mAs.
TRUE
What parameter causes helical slices to be reconstructed so they overlap?
Reconstruction interval
(TRUE or FALSE) The CT number calibration test is a test run to measure the CT number of water in a water phantom.
TRUE
On a conventional CT scan if we want 5mm slices with 1mm over lap, the table increment should be ___mm.
To have a 1mm overlap, the table increment must be 1mm less than the slice thickness.

5mm-1mm= 4mm
What parameter allows adjacent slices to be overlapped without increasing the dose to the pt?
reconstruction interval
Which of the following can be change?
1. Slice thickness from an MDCT helical scan
2. the slice overlap from a single row detector scanner helical scan
3. the slice thickness from a single row detector scanner helical scan
1. the slice thickness from an MDCT helical scan
2. the slice overlap from a single row detector scanner helical scan
Which of the following values for pitch would stretch the x-ray helix the most?
1. 1.5
2. 1.0
3. 0.8
4. 0.5
1. 1.5
What parameter determines how penetrating the x-ray beam will be?
kVp (penetration/contrast)
Which of the following would be used in a high resolution study of the temporal bones?
1. reduced slice thickness
2. reduced FOV
3. sharp filter
ALL (1, 2, 3)
Which of the following would be used to better visualize low contrast resolution?
1. decreased mAs
2. sharp filter
3. narrow window width
3. narrow window width
(TRUE or FALSE) As FOV increases, pt dose decreases.
TRUE
(TRUE or FALSE) As pitch increases, pt dose decreases.
TRUE
(TRUE or FALSE) As slice thickness increases, pt dose decreases.
TRUE
(TRUE or FALSE) Increasing the window level will make the image appear darker.
TRUE
For the phantom test, one hole & one space is called:
line pair
What is spatial resolution expressed in?
line pairs
What is the equation for pitch?
pitch = movement of table in one
gantry rotation /
slice thickness
Narrow window width (Increases/Decreases) contrast of an image.
Increases contrast
A low window level makes the image appear (brighter/darker).
brighter
(TRUE or FALSE) Following the HIPPA guidelines, you may give a pt's medical info to another employee only if it is needed to do their job.
TRUE
If the mA of a 2s brain scan is doubled and all other parameters are not changed the dose is:
doubled
What does PTT stand for?
Partial Thromboplastin Time
Renal function refers to:
Kidney
(TRUE or FALSE) Signed consent forms are not required by law in every state.
TRUE
What is the normal range for PT (prothrombin time)
10-14s
What is the normal diastolic pressure range for adults?

What is the normal systolic pressure range for adults?
(d)60-80

(s)110-140
The result of which of the following lab tests may impact the decision to administer IV contrast?
1. BUN
2. Creatine
3. PT
ALL (1, 2, 3)
On a multi-row detector scanner a radiation penumbra may be found:
only on the first & last slices of the slice volume
What action would you take if a pt arrives with an obvious head trauma, expecting a CT of the brain, but the paperwork requests a pelvic CT?
clarify with the ordering physician
(TRUE or FALSE) During a CT scan, the pt must be monitored visually & verbally.
TRUE
(TRUE or FALSE) Decreasing the mAs, decreases the dose to the pt.
TRUE
(TRUE or FALSE) Increasing the pitch during a scan decreases the dose to the pt.
TRUE
1 rem = ___ rad
1
1 Gy = ___ rad
100
1 Sv= ___rem
100
The average pulse rate for an infant is:
100 - 180
The average pulse rate for a child is:
95 - 110
Normal pulse rate for adults:
70 - 100
The most important consideration in the care of an unconscious pt is to ensure that:
air passages are clear
(TRUE or FALSE) The human embryo/fetus is most sensitive to radiation in the first trimester.
TRUE
What is the typical skin dose for a brain scan?
1-3rads
If there is no overlap or gap between adjacent slices of a CT scan, CTDI (is greater than/ less than/ equals) MSAD
equals
A normal adult has how many respiration's per minute?
12-20
What is the normal range for the BUN?
5-25
Which of the following tests are not an indication of renal function?
1. BUN
2. Creatine
3. PTT
PTT
(TRUE or FALSE) A typical indication of shock may include grayish skin tone, hypotension, or tachycardia.
TRUE
Platelets are small:
cell fragments necessary for blood coagulation
Which of the following reduces pt dose at the expense of increasing the noise on an image?
1. kVp
2. pitch
3. table increment
4. mAs
4. mAs
(TRUE or FALSE) Some possible long term effects of radiation exposure include: cataracts, cancer, and a decrease in life expectancy.
TRUE
CPR must be administered to a cardiac arrest victim with in a maximum of ___ minutes before there is a risk of brain damage.
4 mins
(TRUE or FALSE) Radiation penumbra is radiation that extends outside of the imaging region.
TRUE
(TRUE or FALSE) Radiation penumbra is accounted for in the calculation of MSAD
TRUE
What is the normal range for Creatine?
0.6 - 1.7
The Code of Ethics is a
guideline
The Rules of Ethics are
enforceable
Normal oral temperature is
97 - 99degrees
Peds pulse range:
95 -110
To modify a standard CT protocol so that it is appropriate for children, which of the following should be decreased?
1. pitch
2. kVp
3. mAs
2. kVp
3. mAs
When injecting a hypertonic solution into the vascular space what happens?
there is a net movement of water into the vascular space.
What are some common pt reactions to IV contrast? (8)
warmth at the injection site, headaches, nausea, vomiting, chills, minor hives, sweating, or metallic taste
(TRUE or FALSE) All contrast media (HOMC & LOMC) are hypertonic to blood plasma.
TRUE
LOCM typically has a (higher/lower) concentration of particles compared to blood.
higher
(TRUE or FALSE) LOCM is used more frequently in CT than HOCM because high osmolar contrast tends to cause more adverse reactions than LOCM.
TRUE
(TRUE or FALSE) The barium sulfate used in CT are less concentrated than those used in conventional radiography.
TRUE
Barium sulfate oral contrast media would be selected instead of iodinated oral contrast media because:
1. it passes through the GI tract more quickly
2. the trauma pt may have a perforated bowel
3. the contrast media stays more dense in the distal GI tract
3. the contrast media stays more dense in the distal GI tract
Which of the following may help to reduce adverse reactions resulting from the administration of IV contrast media?
1. use high osmolar contrast media
2. administer an antihistamine prior to the IV contrast injection
3. increase the rate of injection
2. administer an antihistamine prior to the IV contrast injection
What oral contrast agent is better for opacifying the distal small intestine?
1. ionic iodinated contrast
2. non-ionic iodinated contrast
3. barium
3. barium
Iodinated IV contrast agents perfuse normal:
1. liver tissue
2. brain tissue
3. thecal sac
4. lymph nodes
1. liver tissue
What are the most common adverse reactions to oral contrast? (4)
Diarrhea, abd pain, cramping, and flatulence
A delay of about ___ seconds after the start of the IV contrast injection should be used for a helical scan of the neck.
35s
If there is dowbt regarding the sterility of the contrast media the contrast should be:
discarded
What is the most common catheter size used in CT?
18 - 22g
Viscosity is a measure of a fluid's:
thickness
The viscosity of IV contrast can be reduced by:
heating it
Why is the cephalic vein less desirable for injection than the basilic vein?
the flow may be impeded as the pt's arms are raised.
IV contrast agents used in CT increase the attenuation of the x-ray beam due to the concentration of ______ in the agent.
Iodine
The concentration of molecular particles in the contrast is known as the:
Osmolality
The order to the (3) phases of enhancement are:
1. Bolus
2. Non-equilibrium
3. Elquilibrium
The difference in density of ____ HU between the aorta and the ivc would indicate the non-equilibrium phase of enhancement.
10-30
There is substantial enhancement of the liver compared to tumors during the ______ phase, but during the ______ phase there is the possibility of tumor enhancement, which may make hepatic tumors isodense with liver tissue.
non-equilibrium, equilibrium
The hepatic arterial phase occurs approximately ____ seconds after the start of the injection.
20-40s
The portal venous phase occurs approximately _____ seconds after the start of the injection
60-90s
What is the osmolality of blood plasma?
285mOsm/kg
For the CT Chest what is the delay?
20-25s
CT of the pancrease what is the delay?
50-60s
Exams to rule out ____ would indicate the use of IV contrast media in the chest.
1. lymphoma
2. hilar mass
3. arotic dissection
ALL (1, 2, 3,)
(TRUE or FALSE) To best visualize the stomach wall, the pt should drink water last.
TRUE
How long does it take to inject 150ml of contrast media with an injection rate of 2ml/sec?
150/2= 75s
What is the heating unit on the power injector used for?
decreasing the viscosity of the contrast
(TRUE or FALSE) Concentration of the iodine, the osmolality of the iodine, and the viscosity of the iodine all can affect the pt's tolerance to the IV contrast agent.
TRUE
intraarticular means:
into the joint
Intravenous means:
IV
Intrathecal means:
into the spine
Oral means:
by mouth
(TRUE or FALSE) The contrast between a lesion & surrounding tissue may improve, degrade or be unchanged.
TRUE
What is the injection rate for a CTA?
4-5ml/s
CT scan of the brain to best visualize MS plaques uses a delay of:
45min
What is the appropriate cate to give to a pt with diabetes?
1. if IV contrast use LOCM
2. if pt is using Metformin advise them to stop taking it 48 hours prior to the exam
3. if pt is using Metformin advise pt to stop taking it 48 hours after the exam.
1 & 3
Where is cerebrospinal fluid (CSF) produced?
Choroid Plexus which originates in the ventricles of the brain
Where would you expect to find cerebral spinal fluid? (2)
Subarachnoid space
4th ventricle of the brain
In order to best visualize the anatomical relationship between the pituitary & sella turcica what kind of images would be best?
coronal
What is the range of anatomy that should be covered for examination of one intervertebral disk space?
from the pedicle of the vertebra above the disk to the pedicle of the vertebra below the disk
(TRUE or FALSE) Vessels such as the internal carotid artery and the jugular vein will enhance or become brighter on the CT image following contrast, while the lymph nodes will not enhance during the first several minutes.
TRUE
What cranial nerves can be visualized in a study of the soft tissue neck?
IX - glossopharyngesal
X - vagus
XI - accessory
XII - hypoglossal
In order to generate a 3D shaded surface rendering of the hips, the ____ data is used directly by the 3D reconstruction software.
image
What is the appropriate range of coverage for a coronal sinus study?
dorsum sella to anterior frontal sinus
(TRUE or FALSE) IV contrast is usually NOT administered to rule out a herniated disk.
TRUE
(TRUE or FALSE) The entire thoracic spine is not routinely scanned with transverse CT slices.
TRUE - Axial slices are normally obtained
(TRUE or FALSE) Sagittal & coronal images of an adult spine may not directly colledcted from a CT scan
TRUE - Axial then reformatted
What cranial nerves might be visualized in the IAC study? (2)
VII - facial
VIII - vestibulocochlear
What might you do to reduce the lordotic curve when performing a scan of the L-spine?
place a wedge under the pt knees.
What are the (3) reference lines when scanning the brain?
* CML - cantomeatal line
* OML - orbitomeatal line
* IML - infraorbiatl meatal line
How should the mAs be varied to compensate for an increase in noise on an image caused by reducing slice thickness?
increase mAs
What is the primary reason to have a pt phonate the letter "e" during a CT exam of the larynx?
demonstrates vocal cord mobility
Name a few techniques which can be employed in order to minimize pt motion.
* suspend respiration
* shorter scan time
* pt immobilization devices
What does the mediastinum include?
* heart
* great vessels
* trachea
* bronchi
* esophagus
*thymus
*lymph nodes
*thoracic duct
* phrenic & vagus nerves
How is the pt positioned for a CT scan of the chest?
supine with arms raised over head
Which of the following may reduce the out of field artifact?
1. Increasing the scan field of view
2. Reducing the reconstruction field of view
3. reducing slice thickness
4. increasing the matrix
1. Increasing the scan field of view.
A cone beam artifact may look like:
Stars or Spokes coming from structures around the edge of the image.

Occurs on MDCT
Define Beam Hardening:
process by which lower energy photons are absorbed by the tissues.
Which of the following affects beam hardening?
1. types of tissues the beam passes through
2. thickness of the tissues traversed by the beam
3. the energies of the photons in the beam
ALL (1, 2, 3)
(TRUE or FALSE) CT artifacts are the annoying anomalies which sometimes appear in CT images.
TRUE
Which of the following would display the greatest amount of partial volume artifact?
1. 10mm slice from a 20 slice study
2. 5mm slice from a 40 slice study
3. 5mm slice from a 20 slice study
1. 10mm slice from a 20 slice study
* The number of slices collected has no affect on the amount of partial volume averaging that occurs.
Which of the following is a result of reducing the slice thickness to reduce partial volume effects?
1. increased noise
2. increased resolution
3. decreased anatomical coverage with the same number of slices
ALL (1, 2, 3)
(TRUE or FALSE) Beam hardening can cause CT # inaccuracies, streaks in image, & cupping artifact.
TRUE
What would happen if the filter at the aperture of the x-ray tube was removed?
beam hardening artifact would decrease
What is the cause for the cupping artifact?
tissues of the body attenuate low energy photons
Which of the following would make noise in the image appear less noticeable?
1. increased window width
2. increased mAs
3. increased slice thickness
ALL (1, 2, 3)
What would cause two parallel lines seen on a localizer image?
two faulty detector elements
How would we expect metal to affect the appearance of a localizer image?
the CT #'s of the tissues in the image will be misrepresented & there will be no streaks
Why must we choose a scan field of view which is larger than the anatomy to be scanned?
to avoid out of field artifacts
What refers to the increase in the average energy of the photons which comprise the x-ray beam as it penetrates tissue.
Beam Hardening
(TRUE or FALSE) Cone beam artifacts can occur on MDCT scanners when the x-ray beam that is divided over multiple slices is more than 20mm thick.
TRUE
Decrease slice thickness, (increase/decrease) noise.
INCREASE noise
Decrease slice thickness (increase/decrease) partial volume effect.
DECREASE partial volume
(TRUE or FALSE) Edge gradient effects are reduced by using detectors with smaller apetures, thinner slices, & higher data sampling rates.
TRUE
Which of the following would reduce the partial volume effect?
1. increased reconstruction FOV
2. increased mAs
3. decreased matrix
4. decreased slice thickness
4. decreased slice thickness
(TRUE or FALSE) Metal artifacts can be made more or less severe depending upon the amt, chemical makeup, & geometry of the metal object.
TRUE
Which of the following would eliminate a ring artifact?
1. re-calibration of the detector elements.
2. removal of metal
3. decreased matrix
4. increased mAs
1. re calibration of the detector element
CT x-ray tube arcing can occur because of _______ the x-ray tube.
1. impurities in the oil outside
2. tungsten gas inside
3. tungsten solids in the oil inside
1 & 2
If an algorithm to correct for the cupping artifact is applied too aggressively to the data for a head image, the ______ of the image would be too bright.
Center
If the pt's arms are placed at their sides during a chest exam if the scan FOV is 33cm, which of the following might occur?
1. Beam hardening
2. Out of field artifact
3. cone beam artifact
1 & 2
How do you reduce partial volume artifact?
decreasing the slice thickness
Which of the following will affect the hardening of an x-ray beam?
1. tissue density
2. tissue thickness
3. kVp
ALL 1, 2, 3
In which direction are streaks from the edge gradient effect oriented?
parallel to the direction of the sharp density difference interface
Which of the following may be a result of partial volume averaging?
1. decreased sharpness of edges
2. inaccurate CT numbers
3. ghosting of tissue boundaries
1 & 2
The service engineer should be notified about which of the following?
1. frequent bad streaks on the inferior slices of head scans
2. consistent circle on the images
3. frequent bad streaks throughout the entire image
2 & 3
Frequent bad streaks throughout the entire image may indicate:
tube arcing
As slice thickness is decreased, the partial volume artifact & edge gradient effect both are:
decreased
A _____ artifact is a streak artifact which arises from a high spatial frequency interface between tissues with a great difference in density.
1. tube arcing
2. edge gradient
3. cone beam
4. ring
2. edge gradient
Which of the following would decrease the effects of beam hardening artifacts?
1. increased kVp
2. increased mAs
3. increased scan time
1. increased kVp

mAs & scan time do not affect beam hardening
Which of the following strategies would not help us differentiate possible pathology from a partial volume artifact?
1. inspection of adjacent slices
2. collect additional thinner slices through suspicious region
3. rescan & decrease pitch (without changing the slice thickness)
1. inspection of adjacent slices
2. collect additional thinner slices through suspicious region
Which of the following strategies minimizes beam hardening artifact from dense contrast media?
1. contrast solution can be diluted
2. the scan can be performed with a slight delay
3. the scan can be performed in the opposite direction
ALL (1, 2, 3)
(TRUE or FALSE) Tube arcing might cause an increased appearance of noise on the images.
TRUE