PET/CT Midterm
What, as a general rule, is the normal range for serum creatinine? A. 0.6 to 1.7 mg/dL B. 0.3 to 0.77 mg/dL C. 0.2 to 1.77 mg/dL D. 6 to 17 mg/dL
A. 0.6 to 1.7 mg/dL
How many centigray (cGy) are equivalent to 1 radiation absorbed dose (rad)? A. 1 B. 10 C. 100 D. 1000
A. 1
In an x-ray tube, of the energy applied to the system, the percentage of x-rays that exit is A. 1% B. 10% C. 50% D. 99%
A. 1%
What, as a general rule, is the normal range for partial thrombo-plastin time (PTT)? A. 25 to 55 seconds B. 15 to 25 seconds C. 10 to 15 seconds D. 5 to 25 seconds
A. 25 to 55 seconds
How many grams of iodine will be delivered when 150 mL of an agent with a concentration of 300 mgI/mL is injected? A. 45 g B. 450 g C. 4500 g D. 45,000 g
A. 45g
What is another name for the bolus phase of tissue enhancement? A. Arterial phase B. Venous phase C. Nonangiographic phase D. Aortic phase
A. Arterial phase
How are delayed reactions to intravascular iodinated contrast media defined? A. As reactions occurring between 1 hour and 1 week after contrast medium injection B. As reactions occurring between 1 hour and 1 day after contrast medium injection C. As reactions occurring between 1 day and 1 month after contrast medium injection D. As reactions occurring between 1 day and 1 week after contrast medium injection
A. As reaction occurring between 1 hour and 1 week after contrast medium injection
Which is the correct formula for dose-length product (DLP)? A. DLP = CTDIvol × scan length B. DLP = CTDIvol ÷ scan length C. DLP = CTDIvol + scan length D. DLP = CTDIvol × 2 × scan length
A. DLP = CTDIvol × scan length
What causes the edge gradient effect? A. Irregularly shaped objects that have a pronounced difference in density from surrounding structures B. More than one type of tissue is contained within a voxel. C. Patient motion D. Anatomy that extends out-side of the selected SFOV
A. Irregularly shaped objects that have a pronounced difference in density from surrounding structures
Noise in PET imaging arises from: A. Random and scatter coincidences B. Attenuation effects C. Radioactive decay D. The reconstruction process E. All of the above
A. all of the above
How is noise is measured? A. By finding the standard deviation of the CT numbers within the region of interest B. By finding the mean of the CT numbers within the region of interest C. By finding the standard median of the CT numbers within the region of interest D. By finding the variance of the CT numbers within the region of interest
A. by finding the standard deviation of the CT numbers within the region of interest
In PET reconstruction, filtered back-projection A. creates streak or star artifacts B. eliminates streak or star artifacts C. increases contrast in the image D. equates with iterative reconstruction
A. creates steak or star artifacts
In PET scanning, blank scans are performed A. daily B. quarterly C. annually D. upon installation
A. daily
In a PET scanner, the determination of the annhilation event is made possible by A. electronic collimation. B. parallel hole collimation. C. back-scatter projection. D. filtered back-scatter projection.
A. electronic collimation
With PET radionuclides, the higher the energy particle, A. the greater the mean range for the travel of the positron. B. the shorter the mean range for the travel of the positron. C. won't have an effect on the mean range for the travel of the positron. D. it reduces the mean range for the travel of the positron.
A. the greater the mean range for the travel of the positron
The purpose of using an aluminum filter in CT scanning is A. to absorb the very-low-energy x-rays B. to act as an upper level discriminator C. to act as a window D. to attenuate the high-energy x-rays
A. to absorb the very-low-energy x-rays
In a PET system, gain update calibration should be performed at least A. weekly B. quarterly C. annually D. following repair
A. weekly
What is the purpose of windowing (window level and window width) of a set of CT images?
Allowing the certain tissue to be displayed while the other values (HU) that are below and above the set window to be out of range with lower intensity.
What is the quality factor for the diagnostic x-rays that are used in CT? A .0 B. 1 C. 5 D. 10
B. 1
What, as a general rule, is the normal range for platelet count? A. 100,000 to 300,000 cubic millimeters B. 150,000 to 400,000 cubic millimeters C. 175,000 to 375,000 cubic millimeters D. 200,000 to 500,000 cubic millimeters
B. 150,000 TO 400,000 cubic millimeters
Who often share the responsibility for performing and documenting quality control tests? A. CT technologists and physicians B. CT technologists and medical physicists C. Physicians and medical physicists D. Medical physicists and scanner manufacturers
B. CT technologists and medical physicists
Which is an example of a moderately adverse idiosyncratic patient reaction? A. Cough B. Hypertension C. Convulsions D. Itching
B. Hypertension
What causes spiral interpolation artifacts? A. Too few samples B. Images are created from views not in the same plane C. Patient motion D. The x-ray beams are composed of different energies
B. Images are created from views not in the same plane
Which is the name for a long catheter that is inserted through the large veins of the upper arm? A. Central venous catheter B. Peripherally inserted central catheter C. Midline catheter
B. Peripherally inserted central catheter
ackprojection is associated with: A. helical/spiral scanning. B. artifacts. C. increased image sharpness. D. pitch
B. artifacts
How does filtration affect the radiation dose? A. By increasing rotation to greater than 360° B. By removing some of the soft x-rays C. By decreasing the pitch D. By increasing scan field diameter
B. by removing some of the soft x-rays
In PET reconstructions, OSEM and RAMLA are most commonly used over FBP because A. they are faster with less data storage. B. of reduced streak artifacts and image noise. C. of increased image contrast. D. a fewer mispositioning artifacts.
B. of reduced streak artifacts and image noise
Large array parallel processors are responsible for: A. executing several tasks sequentially. B. performing numerous tasks simultaneously . C. assessing faulty detector arrays D. hardening the x-ray beam.
B. performing numerous tasks simultaneously
Using a higher mA.... A. results in an increase in image noise B. results in an increase in contrast resolution C. results in a decrease in dose to the patient D. shortens the imaging time for the patient
B. results in an increase in contrast resolution
On a PET sinogram, the horizontal row represents A. each angle from which the projection was taken. B. the count profile across the distance of the gantry as seen from each angle. C. the set of reconstructed transaxial slices as seen from each angle. D. the angle from which the projection is taken over 180 degrees.
B. the count profile across the distance of the gantry as seen from each angle.
In PET imaging, the purpose of a transmission scan is A. for quality control purposes. B. to compensate for the variable attenuation in tissues. C. for registration purposes. D. to provide data for scatter correction.
B. to compensate for the variable attenuation in tissues
How many radiation absorbed dose (rad) are equivalent to 1 gray (Gy)?. A. 10 B. 50 C. 100 D. 1000
C. 100
About how many times greater is radiation exposure from a whole body CT scan than from a chest x-ray? A. 5 times greater B. 10 times greater C. 100 times greater D. 1000 times greater
C. 100 times greater
What is the approximate CT number for bone? A. 0 B. 10 C. 1000 D. 100
C. 1000
What is the most common formula for calculating the dose of intravascular contrast for pediatric CT studies? A. 0.5 mL/kg B. 1 mL/kg C. 2 mL/kg D. 4 mL/kg
C. 2mL/kg
What is the trade-off for the excellent low-contrast resolution that is seen on CT images? A. Less patient comfort during examinations B. Decreased detector efficiency C. A relatively high radiation dose D. The need for highly-trained technologists
C. A relatively high radiation dose
What type of contrast agent has osmolality equal to that of blood? A. High-osmolality contrast media B. Low-osmolality contrast media C. Isosmolar contrast media
C. Isomolar contrast media
A high-osmolality contrast media can be up to how many times greater than the osmolality of blood? A. Two times B. Four times C. Seven times D. Ten times
C. Seven times
Which is not a feature CT systems use to minimize beam hardening? A. Filtration B. Calibration correction C. Slowing gantry rotation speed D. Beam-hardening correction software
C. Slowing gantry rotation speed
In a dedicated PET scanner, there is a photomultiplier tube (PMT) for A. each crystal. B. every other crystal. C. a group of crystals. D. every ring in crystals.
C. a group of crystals
In PET imaging, a large particle range results in A. better resolution of annihilation events. B. an overcalculation of the annihilation event from the positron-emitting atom. C. a slight mispositioning of the annihilation event from the positron-emitting atom. D. truer positioning of the annihilation event with the positron-emitting atom.
C. a slight mispositioning of the annihilation event from the positron emitting atom.
In a CT scanner, the oil bath that may surround the rotating anode tubes serves to A. make the tubes rotate more quickly B. make the tubes rotate more smoothly C. cool the tubes D. provide efficient conduction of the current
C. cool the tubes
The standard uptake value is useful in A. performing attenuation correction B. calculating scatter correction C. differentiating between malignant and benign tissue D. determining the time span between injection and scan
C. differentiating between malignant and benign tissue
The line of response (LOR) A. is determined for each crystal within a detector system. B. is determined for each detector system and each crystal type. C. is created by the detection of an annihilation photon pair by opposing crystals. D. is created to perform scatter correction techniques.
C. is created by the detection of an annihilation photon pair by apposing crystals.
Modern CT scanners rely on _____ to process acquired data. A. supercomputers B. mainframe computers C. minicomputers D. microcomputer
C. minicomputers
Computed tomography (CT) scanning accomplishes all of the following EXCEPT A. minimal superimposition of tissues B. improved contrast resolution C. reduction of radiation dose compared to conventional radiography D. differentiation of tissue densities
C. reduction of radiation dose compared to conventional radiography
Spatial resolution on PET scanners is determined primarily by A. the collimator used and the size of the septa. B.the size of the crystals and their separation. C. the sensitivity of the system and the number of rings. D. the scatter correction and the accuracy of the attenuation correction.
C. the sensitivity of the system and the number of rings
patial resolution in PET is the best at the of the gantry.
Center
The two types of x-rays produced in an x-ray tube are and _____________.
Characteristic, Bremssstrahlung
What, as a general rule, is the normal range for prothrombin time (PT)? A. 2 to 5 seconds B. 6 to 10 seconds C. 8 to 12 seconds D. 11 to 14 seconds
D. 11 to 14 seconds
Who typically determines the proper protocol for a CT examination? A. The ordering physician B. A technologist C. The attending nurse D. A radiologist
D. A radiologist
What is a reconstruction kernel? A. A unit of data in a reconstructed CT image B. The entire data set used to produce reconstructed images in CT C. A measurement used to determine the data set used for CT reconstruction D. An algorithm that defines the clinical application and amount of image smoothing applied in the reconstruction
D. An algorithm that defines the clinical application and amount of image smoothing applied in the reconstruction
What, as a general rule, is the normal range for blood urea nitrogen (BUN)? A. Between 0 and 2.5 mg/dL B. Between 2 and 15 mg/dL C. Between 7 and 45 mg/dL D. Between 7 and 25 mg/dL
D. Between 7 and 25 mg/dL
Which is not a strategy for reducing CT radiation dose? A. Consider alternative modalities B. Limit the region covered C. Consider patient shielding D. Maximize the use of thin slices
D. Maximize the use of thin slices
What is the best way to reduce metallic artifact? A. Select a SFOV that is larger than the patient. B. Recalibrate the scanner C. Give the patient clear breathing instructions D. Minimize the metal present in the SFOV
D. Minimize the metal present in the SFOV
The normalization scan corrects for which of the following? A. Variations in LOR density across the transaxial field of view B.Variations in sensitivity in the axial direction C. Variations in measured count rate from a uniform source, from one line of response to the next D. All of the above
D. all of the above
Which of the following affect the value obtained for the SUV? A. How the region of interest is defined B. How the count rate within the region of interest is determined C. Whether a partial volume correction is applied D. All of the above
D. all of the above
Which is not a manifestation of patient motion? A. streaking B. blurring C. ghosting D. concentric rings
D. concentric rings
In PET imaging, blank scans are used A. to subtract background B. to calculate scatter correction C. to determine deadtime D. in attenuation correction
D. in attenuation correction
All of the following are true about increasing the kVp setting EXCEPT A. it selects the maximum possible energy of the x-ray beam B. it defines the fraction of photons that will reach the detectors C. it affects the radiation exposure to the patient D. it increases beam hardening
D. it increases beam hardening
Collimators in CT scanning are used to do all of the following EXCEPT A. limit the beam size B. reduce scattered x-rays C. define slice thickness D. offset the alignment of the tube and detector array to optimize the beam location
D. offset the alignment of the tube and detector array to optimize the beam location
To assure fast scan times and immediate data processing, CT computers depend on: A. distributed processing. B. multitasking C. multiprocessing D. parallel processing.
D. parallel processing
Regarding septa on a PET system, all of the following are true except A. they limit the field of view of events to those within the same detector ring, or events with contiguous planes. B. they reduce the number of scatter and random events from outside the plane. C. they allow for the system to operate in 2D mode. D. they allow for the system to operate in 3D mode.
D. they allow for the system to operate in 3D mode.
In a blank scan, failure of a detector block is seen as a _________.
Diagonal white line
A 2D image will have a higher scatter fraction than a 3D image. (True or false)
False
A larger value for pitch indicates higher radiation exposure to the patient. (True or false)
False
Subtraction of scatter in a PET image does not affect the signal-to-noise ratio characteristics of the image. (True or false)
False
System sensitivity is lower in 3D imaging than in 2D imaging. (True or false)
False
True or False? For a given set of machine parameters (mAs, slice thickness, and pitch), organ doses are higher for adults than for children.
False
True or False? Tube arcing is patient-induced artifact.
False
CT voxel values are given in terms of _______________ , which express the attenuation of a given tissue relative to that of ____________.
Hounsfield units, water
Describe the goal and concept behind time-of-flight PET.
Short decay time and better signal-noise ratio
The raw data image from a PET scan is called a
Sinogram
Explain the meaning of pitch
The table movement of the patient going through the gantry. The smaller the pitch the longer the scan time and increased patient dose there is. If the pitch is bigger then it can cause gaps and miss sections of the body that are needing to be imaged and also degrades contrast.
What is the meaning of SUV (standardized uptake value)?
To differentiate between benign and malignant tumors
The x-ray beam used for CT imaging is polychromatic. (True or false)
True
Time-of-flight PET requires a scintillation crystal that has very high light yield. (True or false)
True
True or False? An undesired surge of electrical current within the x-ray tube causes tube arcing.
True
True or False? The computed tomography dose index (CTDI) can only be calculated if slices are contiguous.
True
True or False? The effective dose attempts to account for the effects particular to the patient's tissue that has absorbed the radiation dose.
True
When a PET tomograph is used in both 2D and 3D modes, the normalization factors and well counter calibration factor must be acquired separately for each mode. (True or false)
True
What is another name for the nonequilibrium phase of tissue enhancement? A. Arterial phase B. Venous phase C. Nonangiographic phase D. Aortic phase
Venous phase
Evidence of a repeating artifact related to the tomograph's bed positions is corrected by __________.
acquiring a new normalization scan
Any object seen on the image that is not present in the object scanned is considered an
artifact
The three general phases of tissue enhancement commonly discussed in CT are the phase, the nonequilibrium phase, and the equilibrium phase.
bolus
True or False? Adding an iodinated agent to the bloodstream will temporarily decrease the beam-attenuating ability of the blood.
false
True or False? Central venous access devices (CVADs) are the optimal choice for contrast administration.
false
True or False? The practice of acquiring a signed consent form is a practice that is universally accepted for routine CT examinations.
false
True or False? Tumors and other disease processes always have different attenuation coefficients than those of their surrounding tissue.
false
refers to the relationship between CT numbers and the linear attenuation values of the scanned object at a designated kVp value.
linearity
In a PET tomograph using rod sources for attenuation correction, the blank scan is used to __________ the transmission lines of response, and must be analyzed and saved _________.
normalize, daily
is a property of intravascular contrast media that refers to the number of particles in solution, per unit liquid, as compared with blood.
osmolality
The unit of x-ray exposure in air is the
roentgen
Which of the following contributes the most to dead time? A. Random coincidences B. Scatter coincidences C. Single events D. Multiple coincidences
single events
True or False? Prior to an examination, scanner calibrations and tube warm-up procedures should be done while the room is free of both patients and CT staff.
true
True or False? Warming a contrast agent reduces viscosity.
true
refers to the ability of the scanner to yield the same CT number regardless of the location of an ROI within a homogeneous object.
uniformity
is a physical property that may be described as the thickness or friction of the fluid as it flows.
viscosity
