Quizzes/Tests Flashcards
xCollimation of the CT x-ray beam that occurs before the detectors, is primarily for:
a.patient protection
b.focusing the primary beam
c.determining slice thickness
d.the absorption of scatter radiation
d.the absorption of scatter radiation
CT numbers are usually provided in the form of:
a.milligrays
b.Hounsfield units
c.linear attenuation coefficients
d.EMI numbers
b.Hounsfield units
The algorithm that produces motion free images from a helical CT scan is called:
a.Fourier reconstruction
b.filtered back projection
c.interpolation
d.convolution
c.interpolation
The CT window controls the ______________ of the CT image as it appears to the viewer.
a.shades of grey and linear attenuation coefficients
b.spatial and contrast resolution
c.contrast and brightness
d.density and detail
c.contrast and brightness
Voxels that have equal dimensions (cube shaped) are referred to as:
a.anisotropic
b.prospective
c.tropic
d.isotropic
d.isotropic
In what phase of tissue enhancement is the intravenous iodinated contrast in the image below?
a.arterial
b.3 hours post drinking oral contrast media
c.3 hours post injection
d.portal venous
a.arterial
Random noise on a CT image, due to insufficient remnant radiation, appears as:
a.a step artifact
b.decreased brightness
c.fog
d.graininess
d.graininess
The loss of anatomic information between contiguous sections due to inconsistent patient breathing is called:
a.beam hardening
b.misregistration
c.misrepresentation
d.overbeaming
b.misregistration
The signal from the CT detectors must be converted into numerical information, prior to reconstruction, by the:
a.filtered back projection
b.digital to analog converter
c.analog to digital converter
d.array processor
c.analog to digital converter
The process of applying a filter that removes blurring from the reconstructed CT image is termed:
a.interpolation
b.isotropic
c.convolution
d.iterative
c.convolution
The average photon energy of the primary beam of a CT scanner operating at a tube potential of 120 kVp is approximately:
a.40 keV
b.60 keV
c.120 keV
d.100 keV
b.60 keV
The term used to describe the relationship between the linear attenuation coefficient of an object and the calculated CT number is:
a.quantum noise
b.reciprocity
c.quantum mottle
d.linearity
d.linearity
Pixels representing tissues with HU numbers greater than that of water have which of the following types of values?
a.positive
b.zero values
c.less than negative 1,000
d.negative
a.positive
The average photon energy of the CT x-ray beam can be increased by:
a.increasing filtration
b.all choices are correct
c.increasing mAs
d.increasing collimation
a.increasing filtration
A CT image is displayed in a window with a level of 0 and a width of 500. Which of the following statements is correct?
a.pixels with values less than 0 HU will appear white
b.pixels with values between -250 HU and +250 HU will be assigned shades of grey
c.pixels with values between -500 HU and +500 HU will be assigned shades of grey
d.pixels with values between 0 HU and 500 HU will appear white
b.pixels with values between -250 HU and +250 HU will be assigned shades of grey
he measurement of transmitted radiation made by an individual detector is called a(n):
a.Hounsfield unit
b.electronic signal
c.attenuation coefficient
d.ray sum
d.ray sum
An average CT number for blood is:
a.+100 HU
b.+45 HU
c.-20 HU
d.+10 HU
b.+45 HU
Which of the following could be utilized to improve temporal resolution in cardiac CT?
a.decrease in section width
b.increased breath hold
c.axial imaging
d.ECG gating
d.ECG gating
A region of interest (ROI) measurement placed over a portion of CT image provides which of the following?
a.average CT number (HU value)
b.diameter (mm)
c.distance
d.type of pathology
a.average CT number (HU value)
The streaking artifacts, depicted in the image below, is caused by:
a.metal dental fillings
b.detector malfunction
c.beam hardening
d.partial volume averaging
a.metal dental fillings
A contiguous data set means that:
a.images can only be viewed as axial images
b.all images were acquired in single acquisition
c.there is a gap in the data set
d.there is no gap in the image data set
d.there is no gap in the image data set
An insufficient mA was set for a CT scan. The resultant images are noisy; this is known as:
a.quantum mottle
b.photon flux
c.interpolation
d.mA noise
a.quantum mottle
Beam hardening artifacts can be reduced be doing which of the following:
a.acquiring thinner sections
b.utilizing a cone beam
c.decreasing the kVp
d.using reconstruction algorithms
d.using reconstruction algorithms
The main advantage of iterative reconstruction techniques versus filtered back projection is:
a.better handling of noisy images
b.faster reconstruction
c.does not require specification of reconstruction
d.better depiction of bone detail
a.better handling of noisy images
In helical CT, pitch is defined as:
a.table movement in 360 degrees/scan axis
b.reconstructed slice thickness/beam width
c.table movement in 360 degrees/beam width
d.table movement in 360 degrees/slice thickness
c.table movement in 360 degrees/beam width
High-pitch techniques are useful for:
a.fast scans
b.gated cardiac CT
c.accurate multiplanar reconstructions
d.very small findings (such as nondisplaced fractures)
a.fast scans
In helical CT, a low pitch technique might be most helpful for:
a.scanning a young child
b.scanning a tachypneic patient
c.detecting a subtle liver lesion
d.detecting a non-displayed fracture
d.detecting a non-displayed fracture
The major technical challenge in cardiac CT is:
a.contrast resolution
b.three-dimensional reconstruction
c.temporal resolution
d.spatial resolution
c.temporal resolution
Increasing the number of rows in MDCT allows for:
a.greater axial coverage
b.better temporal resolution
c.greater spatial resolution
d.greater contrast resolution
a.greater axial coverage
The process responsible for tissue contrast in CT imaging is:
a.characteristic radiation
b.coherent scatter
c.Compton effect
d.photoelectric absorption
d.photoelectric absorption
Iodine is a good CT contrast agent because:
a.very high contrast in target organs is produced
b.the k-edge (33 keV) is much lower than the energies produced by a 120 kVp x-ray tube
c.the k-edge (33 keV) is near the average diagnostic energy of a 120 kVp x-ray tube
d.it simulates the attenuation of bone due to photoelectric absorption
c.the k-edge (33 keV) is near the average diagnostic energy of a 120 kVp x-ray tube
Beam hardening in x-ray imaging refers to:
a.decreased average x-ray energy as a beam passes through a dense material
b.decreasing x-ray beam strength as it passes through a dense material
c.increased average x-ray energy as the x-ray beam passes through a dense material
d.decreasing x-ray beam due to filtration
c.increased average x-ray energy as the x-ray beam passes through a dense material
Automated exposure compensation uses the topogram (or scout) image to determine:
a.reconstruction filter
b.iterative reconstruction
c.tube current
d.pitch
c.tube current
the goal of automated exposure compensation is:
a.to eliminate the radiation risks from a CT exam
b.to generate images of similar noise in different patient sizes
c.to scan patients of different sizes with the same kV and mAs settings
d.to obtain quality images with acceptable noise
b.to generate images of similar noise in different patient sizes
If the field of view (FOV) is constant, a larger matrix will result in which of the following:
a.smaller pixel size, with low contrast resolution
b.larger pixel size, with better resolution
c.more pixels with better spatial resolution
d.less pixels with increased image noise
c.more pixels with better spatial resolution
The image below depicts which of the following artifacts
a.motion
b.streak
c.beam hardening
d.volume averaging
a.motion
Which of the following window levels would be most appropriate for analyzing a fracture of the skull?
a.- 500 HU
b.0 HU
c.+500 HU
d.-10 HU
c.+500 HU
The image below would most likely have settings of which of the following window widths and window levels?
a.WL 0 HU, WW 500
b.WL + 600 HU, WW 100
c.WL 0 HU, WW 1500
d.WL -600 HU, WW 1500
d.WL -600 HU, WW 1500
When one is viewing a minimum intensity projection (min-IP) image, each pixel represents:
a.the average attenuation occurring within the voxel
b.the maximum attenuation occurring within the voxel
c.the minimum attenuation occurring within the voxel
d.attenuations with the highest and lowest HU values possible
c.the minimum attenuation occurring within the voxel
Changing filters (aka kernals) in filtered backprojection results in:
a.different linear attenuation coefficients
b.different patient dose
c.trade-off between image sharpness and noise
d.reduced patient dose
c.trade-off between image sharpness and noise
To uniformly expose the entire detector array in MDCT, the primary beam is expanded beyond the array. This is called:
a.expanded collimation
b. overranging
c. interpolation X
d. overbeaming
d. overbeaming
Utilizing automatic tube current modulation results in:
a. decreased patient dose
b. improved radiographic contrast
c. decreased radiographic contrast
d. increased patient dose
a. decreased patient dose
Which of the following reconstruction methods can be used to decrease patient dose?
a. filtered back projection
b. iterative
c. interpolation
d. increase pitch
b. iterative
CT protocol should be optimized on the basis of ____to reduce patient dose.
a. suspected pathology
b. age
c. male or female
d. size or weight
d. size or weight
Contact shielding for CT examinations should be placed above and below the patient because of:
a. x-ray beam collimation
b. automatic tube current modulation
c. the rotation of the x-ray tube
d. high kVp techniques
c. the rotation of the x-ray tube
Continuous adjustment of mA during the CT examination is termed:
a. ionization determination
b. pitch adjustment
c. automatic tube current modulation
d. automatic exposure control
c. automatic tube current modulation
Which action could the CT technologist take to decrease patient dose?
a. change the algorithm from soft tissue to bone
b. decrease tube rotation from 360 to 180 degrees
c. decrease the display field of view (DFOV)
d. increase the matrix size
b. decrease tube rotation from 360 to 180 degrees
Dose length product (DLP) is calculated by which of the following?
a. CTDIvol x scan length (mm)
b. CTDIw x scan length (cm)
C.CTDIvol x pitch
d. CTDIvol x scan length (cm)
d. CTDIvol x scan length (cm)
Overbeaming occurs to reduce which of the following?
a. patient dose
b. pitch
c. scan length
d. penumbra
d. penumbra
Which of the following units is used to express the total patient dose from a helical CT exam?
a.Gray
b. Coulomb/kg
c. mGy-cm
d. Sieverts
c. mGy-cm
The radiation dose index calculation that takes into account the variations in absorption that occurs across the field of view due to beam hardening is
termed:
a. CTDIW
b. MSAD
c. CTDI
d. CTDIvol
a. CTDIW
The reduction in intensity of the CT x-ray beam as it passes through patient tissue is termed:
a. Compton scattering
b. photoelectric absorption
C.attenuation
d. filtration
C.attenuation
Which of the following methods can be used to reduce the radiation dose to a pediatric patient requiring a CT exam?
1. reduce mA
2. limit phases of acquisition
3. increase pitch
a. 1 only
b. 1, 2 and 3
c. 1 and 3 only
d. 1 and 2 only
b. 1, 2 and 3
A decrease in the focus to detector distance in a multidetector CT (MDCT) system would result in:
a. decreased patient dose
b. loss of contrast resolution
c. magnification of the image
d.increased paient dose
d.increased paient dose
Whole body risk based upon the radiosensitivity of exposed tissues is estimated using which of the following units?
a.equivalent dose
b. kerma
c. stochastic dose
d. effective dose
d. effective dose
The use of iterative reconstruction techniques for CT data processing results in:
1. decreased noise on the reconstructed image
2. decreased radiation dose to the patient
3. decreased image reconstruction time
a. 1,2, and 3
b. 1 and 2 only
c. 1 only
d. 3 only
b. 1 and 2 only
Which of the following devices is used to measure the patient dose from a CT exam?
a. CTDI
b. ionization chamber
c.OSI
d. Geiger counter
b. ionization chamber
When implementing a scan protocol for a CT of the abdomen without contrast on a pediatric patient (weight 18 kg), which technical factor should be primarily adjusted?
a. reconstruction algorithm
b. detector configuration
c. scan field of view (SFOV)
d. tube milliamperage
d. tube milliamperage
Contact shields made of
may be used to protect radiosensitive organs that lie within the scanned region during a CT exam
a. lead
b. bismuth
C.aluminum
d. molybdenum
b. bismuth
Which of the following technical factors has a direct effect on patient dose?
a. mAs
b. bow-tie filter
c. kVO
d. matrix size
a. mAs
Which of the following would be considered a mild reaction to IV contrast media?
a. dyspnea
b. vomiting
c. pulmonary edema
d. dysphagia
b. vomiting
The injection rate of an automatic injector is set to 1.5 mL/sec. What is the injection time required to inject 150 mL of contrast?
a. 100 seconds
b. 60 seconds
c. 2 minutes
d. 90 seconds
a. 100 seconds
After an intrathecal injection of iodinated contrast for a CT lumbar spine, the patient should be instructed to:
a. rest for 8 to 24 hours with head on pillow
b. rest for 8 to 24 hours with head slightly elevated
C.resume normal activity
d. rest for 8 to 24 hours with head lower than heart
b. rest for 8 to 24 hours with head slightly elevated
Which of the following may be administered to a patient having a severe anaphylactic reaction to IV iodinated contrast media?
1. epinephrine
2. atropine
3. diphenhydramine
a. 1 only
b. 1 and 3 only
c. 1,2, and 3
d. 2 only
b. 1 and 3 only
Which of the following is the preferred range of heart rate for an optimal cardiac CT study?
a. 65 - 75 bpm
b. 75 - 85 bpm
C.90 to 100 bom
d.40 - 50 bpm
a. 65 - 75 bpm
Which oral contrast material could cause peritonitis if there was a perforation in the Gl tract?
a. iohexol
b. iopamidol (Gastrografin)
C.diatrizoate(Hypaque)
d. barium sulfate
d. barium sulfate
Which of the following angiocatheter sizes may be safely used with an automatic power injector with a flow rate set higher than 3 mL/ sec?
1. 18 qauge
2. 20 gauge
3. 22 gauge
a. 1.2 and 3
b. 1 and 2 only
c. 1 only
d. 3 only
b. 1 and 2 only
The range of serum iodine concentration for adequate tissue pacification during contrast enhanced CT exams is:
a. 50 - 60 mg/mL
b. 12 - 20 mg/mL
C.2 - 8 mg/mL
d.30 - 40 mg/ml
C.2 - 8 mg/mL
The use of water as an oral contrast material for CT of the abdomen and/or pelvis provides:
a. high contrast visibility of bowel structures
b. better demonstration of enhancing bowel wall
c. less likelihood of CIN
d. hydration for IV contrast
b. better demonstration of enhancing bowel wall
A/an_____contrast media does not dissociate into charged particles in solution.
a. neutral
b. ionic
C.nonionic
d. osmolality
C.nonionic
Which of the following needle (angiocatheter) sizes would allow for the most rapid administration of IV contrast media?
a. 23 qauge
b. 18 gauge
C.25 gauge
d. 20 gauge
b. 18 gauge
The international normalized ratio (IN) is calculated to standardize which of the following laboratory values?
a. estimated glomerular filtration rate (eGFR)
b. prothrombin time (PT)
c. partial thromboplastin time (PTT)
d. blood urea nitrogen (BUN)
b. prothrombin time (PT)
An intrathecal injection of contrast media is performed for a CT exam of the lumbar spine. The contrast is administered into which of the following:
a. the subarachnoid space
b. the epidural space
c. the subdural space
d. the femoral vein
a. the subarachnoid space
The escape of contrast material from a needle or blood vessel into the subcutaneous tissues is called:
a. infusion
b.extravasation
c. infiltration
d. intravasation
b.extravasation
Risk factors for contrast-induced nephrotoxicity (CIN) include:
1. pheochromocytoma
2. allergy to shellfish
3. dehydration
a. 1 only
b. 3 only
c. 1 and 2 only
d. 2 only
b. 3 only
A patient suffers acute renal failure following an IV injection of contrast media for a tri-phasic liver CT study. This type of reaction would be termed:
a. toxic
b. iatrogenic
c. nosocomial
d. anaphylactic
b. iatrogenic
Which of the following may be considered one of the high-osmolar contrast media?
1. iothalamate meglumine
2. diatrizoate sodium
3. iohexol
a. 1.2 and 3
b. 3 only
c. 1 only
d. 1 and 2 only
d. 1 and 2 only
The escape of contrast material from a needle or blood vessel into the subcutaneous tissues is called:
a. infusion
b.extravasation
c. infiltration
d. intravasation
b.extravasation
Risk factors for contrast-induced nephrotoxicity (CIN) include:
1. pheochromocytoma
2. allergy to shellfish
3. dehydration
a. 1 only
b. 3 only
c. 1 and 2 only
d. 2 only
b. 3 only
Which of the following is considered one of the ionic radiopaque contrast media?
a. iohexol
b. iopamidol
C.oversol
d. iothalamate meglumine
d. iothalamate meglumine
A patient who is extremely lethargic, and very difficult to arouse, is said to be:
a.semicomatose
b. drugged
C.obtunded
d. lethargic
C.obtunded
Direct contraindications to IV administration of iodinated contrast material include:
a. type Il diabetes
b.an eGER of 100
c. multiple myeloma
d. severe, life threatening, prior reaction to IV contrast
d. severe, life threatening, prior reaction to IV contrast
Which of the following medications may be administered to slow down the heart rate for a cardiac CT exam?
a. beta blocker
b. sublinqual nitroglycerine
c. atropine
d. fentanyl
a. beta blocker
Which of the following medications may be administered to dilate the coronary vasculature prior to a CT cardiac exam?
a. aspirin
b. morphine
c. sublingual nitroglycerine
d. beta blocker
c. sublingual nitroglycerine
A normal range for diastolic blood pressure in an adult is:
a.95 - 140 mm Hg
b. 80 - 120 mm Hq
c. 100 - 120 mm Hg
d. 60 - 90 mm Hq
d. 60 - 90 mm Hq
Which of the following is considered one of the iso-osmolar contrast media?
a. iopamidol
b. iodixanol
c. iohexol
d. oversol
b. iodixanol
The potentially serious decline in renal function after IV contrast media administration is called:
a.CIN
b. eGFR
c. renal failure
d. anaphylaxis
a.CIN
Advantages of a saline flush immediately after IV contrast media administration include:
1. reduction in contrast agent dose
2. reduction in CIN
3. reduction in streaking artifact in the vasculature
a. 1 only
b. 2 and 3 only
c. 3 only
d. 1,2 and 3 are correct
d. 1,2 and 3 are correct
Which of the following terms is used to describe a patient who is not breathing?
a. aphasic
b. dyspnea
c. aphagia
d.apnea
d.apnea
A 35 year old male patient is brought to the emergency department at 3:00 am, via ambulance, after a MVA. The patient is unconscious and the emergency physician orders a non contrast head CT
Which of the following would apply?
a. The CT technologist must consult the Radiologist for appropriate consent.
b. The CT technologist must try and “wake” the patient to get consent.
c. The CT technologist must not complete the scan until a legal quardian is contacted.
d. The CT technologist must complete the scan as this is a medical emergency.
d. The CT technologist must complete the scan as this is a medical emergency.
Complete cardiac diastole corresponds to which portion of the cardiac cycle on an ECG?
a P wave
b. PO segment
c.ORS complex
d. T wave
d. T wave
Which of the following may affect a patient’s calculated glomerular filtration rate (GFR)?
a. sex
b. diet
c. weight
d. hydration
a. sex
Which of the following IV contrast agent administration methods provides the greatest overall plasma iodine concentration?
a. direct arterial injection
b. biphasic technique
C.drip infusion
d. bolus injection
d. bolus injection
Which of the following is a nonionic contrast agent?
a. iothalamate
b. iohexol
c. iodamide
d. diatrizoate
b. iohexol
Which of the following is the correct angle of insertion for placing an angiocath into a vein (antecubital space) for IV administration of a contrast agent?
a. 60 degrees
b. 15 to 30 degrees
c. 5 degrees
d. 45 degrees
b. 15 to 30 degrees
A total volume of 125 mL of iodinated contrast media is administered IV via automatic injector in 50 seconds. The flow rate for this injection is:
a. 1.75 mL/sec
b. 125 mL/sec
c. 2.5 mL/sec
d. 0.75 mL/sec
c. 2.5 mL/sec
The condition whereby the patient suffers from a low concentration of oxygen in the blood is called:
a. hypoxia
b. anoxia
c. hypotension
d. hypoxemia
d. hypoxemia
Which of the following reformat techniques is demonstrated in the image below?
a.minimum intensity projection (min-IP)
b.volume-rendered 3D
c.MPR coronal plane
d.maximum intensity projection (MIP)
d.maximum intensity projection (MIP)
What is the CT number for fat?
a.0 HU
b.-100 HU
c.+50 HU
d.+5 HU
b.-100 HU
Number 7 on the image below corresponds to:
a.jejunum
b.duodenum
c.right kidney
d.pancreas
d.pancreas