TEST PREP CT Flashcards
The range of CT numbers, and therefore the number of shades of gray assigned in a CT image, is determined by the:
WW Setting
Which of these technologies uses electromagnetic steering of the electron beam, resulting in two sources of x-rays?
A. Flying focal spot.
B. Dual filament.
C. Dual energy.
C. Focal Spot Duality.
A. Flying focal spot.
Which formula is used to determine linear attenuation coefficients and demonstrates the relationship between radiation intensity and object density?
The Lambert-Beer Law.
What component converts the image signal into a digital format?
Analog-to-Digital Converter (ADC).
Each intervertebral disk includes a soft, gelatinous center, which is surrounded by a tougher outer layer of tissue called the:
Annulus Fibrosis.
What phase of kidney enhancement is optimal for the evaluation of the renal cortex and renal veins?
Corticomedullary Phase.
To obtain quality multiplanar reformations (MPR), which of the following should be used?
A. The largest possible DFOV.
B. Small slice gaps.
C. A soft tissue or standard algorithm.
D. The thinnest possible detector collimation.
D. The thinnest possible detector collimation.
The unenhanced liver appears ______ in CT imaging.
Homogeneous.
The relationship between kVp and patient dose is:
Direct and exponential.
Which of the following is the most common storage medium for the PACS archive?
A. Magnetic tape.
B. Redundant array of independent disks (RAID).
C. DVD.
D. Optical disk.
B. RAID.
What effect does pitch have on image noise?
They are directly proportional.
Which of the following occurs only in MDCT systems due to the cone-beam shape of the x-ray beam?
WIndmill artifact.
In SSCT, the width of the fan-shaped beam corresponds to the selected detector array and the:
Scan field of view (SFOV).
ROI measurements for the ______________ can aid in the diagnosis of fatty infiltration of the liver during a CT abdomen.
Liver & Spleen.
Evaluation of cardiac function in coronary CTA is:
Not possible.
When using prospective gating for a CT exam of the heart, data is acquired during which phase of the cardiac cycle?
Diastole.
Linked computers that are located within the same facility form a(n):
LAN.
The abnormal state of consciousness in which a patient is not easily aroused from a state of confusion is called:
Obtunded.
The data from the detectors is originally transmitted in _____ form.
Analog.
An MDCT third generation machine uses a:
Cone beam.
In-plane Bismuth shielding:
May cause streaking artifact.
Which of the following methods would help to differentiate between stones in the bladder and at the ureterovesical junction (UVJ)?
Placing the pt in a prone position.
A detector configuration that offers two detector sizes, with narrower detectors in the center and wider detectors on either side is called a(n):
Hybrid array.
Which of the following characteristics is useful for acquiring images of the heart and lungs in motion?
A. Spatial resolution.
B. Penumbra control.
C. SNR.
D. Temporal Resolution.
D. Temporal Resolution.
Which of the following parameters would be the most suitable for a CT abdomen and pelvis to evaluate for ureteral calculi?
A. A helical scan with a slice thickness of 2.5 mm or less.
B. An axial scan with a slice thickness of 5 mm.
C. Cine mode with a slice thickness of 0.625 mm.
D. A helical scan with a slice thickness of 10 mm.
A. A helical scan with a slice thickness of 2.5 mm or less.
__________ occurs when an x-ray photon is completely absorbed through ionization of an inner-shell electron.
The photoelectric effect.
Which of the following organs are located within the retroperitoneum?
A. Pancreas.
B. Stomach.
C. Liver.
D. Spleen.
A. Pancreas.
_________ is used as a negative contrast for colonic distension studies because it is readily absorbed by the body.
Carbon Dioxide.
The linear non-threshold model states that:
biological damage is directly proportional to the dose received, with even the smallest dose creating an effect.
The dose deposited outside of the imaged volume from partial rotations is called the:
Overrange dose.
The mechanical aperture responsible for primary beam restriction is called the:
Pre-patient collimator.
All of the following conditions increase risk of contrast media-induced nephropathy, except:
A. Renal cancer.
B. Diabetes mellitus.
C. Obesity.
D. Hypertension.
C. Obesity.
The MSAD equals the CTDI when:
There is NO overlap or gap between slices.
If a CT image exactly replicates a scanned object, what is the image’s modulation transfer function (MTF) value?
1.
A CT image’s MTF value is between 0 and 1. A value of 1 indicates that the image is a replica of the object, while a 0 specifies that no data is present.
The vein that carries blood to the heart from the lower limbs, pelvic organs, and abdominal wall is the:
Inferior vena cava (IVC).
The average CT number assigned for white matter in the brain is approximately:
45.
In CT perfusion imaging of the brain for a patient with a CVA, the ischemic but still viable tissue immediately surrounding the infarct core is called the:
Penumbra.
Effective mAs is calculated using which formula?
mAs / pitch.
CT images of the soft tissue neck should extend from the _________ to the lung apex.
Superior orbital rim.
Which of these dose measurements takes into account the type of tissue being irradiated?
A. Absorbed dose.
B. Slice sensitivity profile.
C. Multiple scan average dose.
D. Effective dose.
D. Effective dose.
For sinus imaging, the acquisition should extend posteriorly to include:
The sphenoid sinus.
Nonconsensual touching of someone else is considered:
Battery.
Which of the following window settings is best for evaluating the liver?
A. WW 1800; WL 400.
B. WW 1500; WL -600.
C. WW 350; WL 50.
D. WW 150; WL 30.
D. WW 150; WL 30.
To reduce the incidence of headaches, post-myelogram patients should:
A. be placed in the trendelenburg position.
B. be placed in the supine position.
C. walk around after the exam.
D. have their head elevated.
D. Have their head elevated.
How much contrast media is typically administered rectally to visualize the rectosigmoid area?
150 to 200 mL.
The ______________ of contrast enhancement occurs when the contrast media has permeated throughout the organ and is evenly diluted in the blood.
Equillibrium Phase.
What can be done if initial scans of the pancreas fail to differentiate the margins of the pancreas from the duodenum?
Give the patient additional oral contrast (water or low attenuation oral contrast).
For CTA imaging, contrast should be injected __________ to avoid streaking artifact from within the brachiocephalic vein.
Into the right arm.
During myelography exams, contrast media is injected into the _______ of the spinal cord.
Subarachnoid Space.
___________ is a stress fracture of the pars interarticularis commonly caused by osteophyte formation.
Spondylosis.
What is the mathematical process used to reconstruct MDCT images using tube rotations just above and below a given slice?
Interpolation.
The ability of the CT system to record spatial frequency and resolve objects is demonstrated by the:
Modulation transfer function (MTF).
The ______ is the table distance traveled in one 360 degree rotation of a helical scanner divided by the collimated width of the beam.
Pitch.
The technique of using 3D reconstruction to provide a viewpoint within the lumen of an object is called:
Perspective volume rendering.
In CT imaging, the voxel depth is equal to the:
Reconstructed section width.
The average time it takes for blood to pass through a given region of brain tissue is the:
Means transit time (MTT).
Which of these represents the approximate HU of muscle?
A. -15.
B. 20.
C. 45.
D. 90.
C. 45.
Coronary CTA images should extend from the ______ to the base of the heart.
Carina.
The spinal cord extends to the level of T12-L1 before tapering and terminating at the:
Conus medullaris.
Protrusion of abdominal contents through the diaphragm and into the thorax is called a(n):
Hiatal hernia.
A low concentration of oxygen in the blood is also called:
Hypoxemia.
__________ can be measured by scanning a specialized phantom containing an assortment of materials to determine if the system’s HU values match the known ranges of the phantom.
Linearity.
In CT perfusion imaging of the brain for a patient with a CVA, the ischemic brain tissue that is beyond repair is called the:
Infarct Core.
The tube housing and cooling oil contribute to ________ filtration.
Inherent.