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CT Midterm

In which part of the CT process are the data converted into shades of gray for viewing? A) Data acquisition B) Image reconstruction C) Image display C. Image Display
What is the name of the process in CT by which different attenuation values are averaged to produce one less accurate pixel reading? A) Volume averaging B) Pixel averaging C) Z axis averaging D) Image averaging A. Volume Averaging
Which is a drawback of using thicker CT slices when imaging? A) They increase the likelihood of missing very small objects. B) They increase radiation dosage. C) They increase the number of slices that are produced. D) They decrease the pixel size. A. They increase the likelihood of missing very small objects.
Which generation of scanners uses a detector array that is fixed in a 360° circle within the gantry? A) First-generation B) Second-generation C) Third-generation D) Fourth-generation D. Fourth-generation
What is an overscan? A) A tube arc greater than 360°. B) A thin x-ray beam passed linearly over the patient. C) The occurrence of ring artifacts. D) Streaking on the CT image. A. A tube arc greater than 360°.
Which is not a segment of the CT process? A) Image reconstruction B) Data acquisition C) Data dispersal D) Image display C. Data Dispersal
What measures the number of photons that strikes the detector, converts the information to a digital signal, and sends the signal to the computer? B. The data-acquisition system
Collimators control the slice thickness by narrowing or widening the x-ray beam. A) True B) False A. True
High-frequency generators are currently used in CT. A) True B) False A. True
What is interpolation? D. A mathematical method of creating missing data
What is the name for the process of converting the data from the attenuation profile to a matrix? A) Attenuation B) Interpolation C) Back projection D) Fourier transform C. Back projection
What is the process of applying a filter function to an attenuation profile called? A) Interpolation B) Convolution C) Back projection D) Progressive reconstruction B
What is the absolute center of the gantry called? A) Median B) Epicenter C) Image center D) Isocenter D
What does the selected display field of view (DFOV) determine? A) The area, within the gantry, from which the raw data are acquired D) How much of the collected raw data is used to create an image
The scan field of view (SFOV) is also called zoom or target. A) True B) False B
How many shades of gray can the monitor display? A) 64 B) 128 C) 256 D) 512 C
What determines the center pixel value in gray scale? A) Window level B) Window width C) Window height D) Window contrast A
Which is the first step in many image display and measurement functions? A. Defining a region of interest
Wider window width settings increase image contrast. A) True B) False B
Where does a localizer image for a CT of the chest usually begin? A) At the top of the head B) At the lower neck C) At mid-abdomen D) At the base of the spine B
In which type of scans doe the CT table move to the desired location and remain stationary while the x-ray tube rotates. A) Helical scans B) Spiral scans C) Localizer scans D) Step-and-shoot scans D
Which generation of CT systems typically used a 360° rotation for each acquisition? A) Fourth generation B) Third generation C) Second generation D) First generation B
What is the name for the slight pause in scanning between data acquisitions? A) Interscan delay B) Interpolation C) Back projection D) Convolution A
The General Electric Lightspeed QX/I scanner system uses 16 detector rows, each 1.25 mm wide, arranged side-by-side along the z axis. If three detector rows are combined, how thick will the resultant slices be? A) 3.75 mm
Why is it important to correctly input the patient's position before the localizer image is obtained? C) Subsequent images will be incorrectly annotated which can result in misdiagnosis and serious medical errors
An examination protocol calls for contiguous, 5-mm slices to be taken and 70 slices are planned. How much of the patient anatomy in the z direction will be covered with cross-sectional slices? A) 75 mm B) 159 mm C) 350 mm D) 700 mm C) 350 mm
What percent reduction in radiation dose do automatic tube current modulations provide without degrading image quality? A) 10% to 25% B) 15% to 40% C) 5% to 50% D) 15% to 60% B) 15% to 40%
What is the tube rotation of an overscan? A) 180° B) 360° C) 380° D) 400° D) 400°
True or False? Slice thickness has a no impact on image quality. A) True B) False B
What is the kVp range for routine body CT for adult patients? A) 80 kvP to 100 kVp B) 120 kVP to 140 kVp C) 80 kVp to 140 kVp D) 100 kVp to 160kVp B
What barrier to communication is likely to occur when the receiver doesn't like portions of the sender's message? A) Fuzzy transmission B) Language C) Receiver distortion D) Assumptions C) Receiver distortion
Studies have shown that what percent of the meaning we derive from communication comes from the nonverbal cues that the other person gives? A) 50% B) 75% C) 90% D) 100% C) 90%
Which is a communication habit to avoid? C) Using false reassurance
True or False? A number of independent studies have established a link between effective communication and a reduction in malpractice claims. A) True B) False A
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
How many methods of verifying a patient's identity are required? A) None B) at least one C) at least two D) at least three C
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
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
What is the first step in the CT process as defined by the text? A) Verify the order B) Obtain the patient's medical history C) Prepare the room D) Verify patient identity C
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. A) True B) False A
Which is considered to be a low-density contrast agent? A) Water B) Carbon dioxide C) Iodine D) Barium B
A low-osmolality contrast media is how many times greater than the osmolality of blood? A) Two times B) Four times C) Seven times D) Ten times A
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
What is the typical single dose of iodinated contrast agents? A) Between 50 and 100 mL B) Between 100 and 150 mL C) Between 150 and 175 mL D) Between 175 and 200 mL B
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
Which plays a major role in nonallergic reactions to contrast medium? A) Osmolality B) Viscosity C) Clearance D) Ionicity A
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
Which is an example of a moderately adverse idiosyncratic patient reaction? A) Cough B) Hypertension C) Convulsions D) Itching B
With intravenous administration, what is the risk of recurrent reaction in a patient with a prior reaction when HOCM is used? A) 5% to 10% B) 16% to 35% C) 10% to 50% D) 100% B
True or False? Warming a contrast agent reduces viscosity. A) True B) False A
Which is the preferred venous access site when a mechanical injector is used? A) Cephalic vein B) Axillary vein C) Superficial dorsal vein D) Antecubital or large forearm vein D
What is another name for the bolus phase of tissue enhancement? A) Arterial phase B) Venous phase C) Nonangiographic phase D) Aortic phase A
What is another name for the nonequilibrium phase of tissue enhancement? A) Arterial phase B) Venous phase C) Nonangiographic phase D) Aortic phase B
When does contrast enhancement typically reach a near-peak in the aorta? C) From 15 to 22 seconds after the start of the injection
True or False? Many PICC lines cannot tolerate the pressure required to inject contrast media at the high injection rates typical of CT examinations that use mechanical injectors. A) True B) False A
Which causes multiple scan average doses (MSAD) to increase? A) Gaps between the slices B) Overlapping slices C) Using single slices B
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
What is the primary criteria in the selection of mAs? A) Patient size B) The region to be scanned C) The clinical indication that prompted the scan D) Cost A
How much do extra images add to the patient's radiation dose from the examination? A) Approximately 1% B) Approximately 10% C) Approximately 25% D) Approximately 50% B
True or False? The computed tomography dose index (CTDI) can only be calculated if slices are contiguous. A) True B) False A
True or False? Overscans decrease the radiation dose. A) True B) False B
Given the same dose of radiation, how many times more likely is it for a 1-year-old infant to develop a malignancy than it is for a 50-year-old adult? A) Six times B) Ten times C) Twenty times D) One hundred times A
When the radiation doses used in adult protocols are used in neonates or young children, the effective dose is up to what percent greater? A) 10% B) 25% C) 50% D) 100% C
Created by: RT2017