CT REGISTRY REVIEW Flashcards
The utilization of half-scan reconstruction can improve which of the following?
A. Uniformity.
B. Contrast resolution.
C. Temporal resolution.
D. Spatial resolution.
C. Temporal resolution.
Half-scan reconstruction consists of a reconstruction of data that was obtained from only a half of a gantry rotation. Utilization of this method allows for the scan time to be cut in half, and improves temporal resolution.
Which of the following is NOT a function of the RIS?
A. Store images.
B. Store orders.
C. Schedule patients.
D. Patient billing.
A. Store images.
RIS, or the radiology information system is used for scheduling patients, storing patient orders, patient billing, and start and end exam functions.
Which term is used to describe the rate that photons pass through an area in a set amount of time?
A. Effective kV.
B. Photon flux.
C. Effective mAs.
D. Photoelectric effect.
B. Photon flux.
Photon flux is the rate that photons that pass through an area, in a set of time. Increasing the rate of photons results in a decrease in noise. Increasing mA, kVp, or the scan time can also increase the photon flux within an image, but this comes at the cost of increased patient dose and decreased contrast resolution.
Which of the following is caused by an increase in the average energy of the x-ray beam?
A. Partial volume averaging.
B. Edge gradient
C. Beam hardening.
D. Streaks.
C. Beam hardening.
Beam hardening artifacts on an image are caused by the increase in the average energy of the x-ray beam.
Image compression that does NOT loose any data is known as:
A. Lossy.
B. Lossless.
C. DICOM.
D. CD-R.
B. Lossless.
Lossless data is compressed without any loss of data.
The name of the program that tests the performance of a CT scanner to ensure that it is performing at an optimal level and meeting standards is:
Quality Control.
Which of the following is a measure of the noise of an image?
A. ROI.
B. SSP.
C. Standard deviation.
D. HU.
C. Standard deviation.
Noise can be measured by observing the standard deviation of a given set of pixels within an ROI.
Which of the following is NOT true about 3D imaging?
A. They require the use of thick slices.
B. They provide the perception of depth.
C. They utilized overlapped images.
D. They require the use of thin slices.
A. They require the use of thick slices.
3D imaging requires thin, overlapped images to create a model that provides the perception of depth.
Which of the following provides optimal imaging of distal upper extremities?
A. Arms by their side in the neutral position.
B. Arms by their side in the pronated position.
C. Arm not of interest removed from the scan field.
D. Arm of interest in the “superman” position.
D. Arm of interest in the “superman” position.
The volume of a voxel is impacted by adjustments to all of the following except:
A. Matrix size.
B. DFOV.
C. Slice thickness.
D. MPR.
D. MPR.
The DFOV, matrix, and slice thickness all impact the volume of voxel.
Of the following, which is a non ionic radiopaque contrast media?
A. Iopamidol.
B. Iodipamide.
C. Iothalamate.
D. Diatrizoate.
A. Iopamidol.
A CT image has a WL of 0 and a width of 300. Which of the following is correct?
A. The CT numbers will range between 0 and 300.
B. The CT numbers will range between 100 and 400.
C. The CT numbers will range between -300 and 0.
D. The CT numbers will range between -150 and +150.
Answer: D
The range of the numbers is referred to as the Window Width and the center of the range is the Window Level.
At which vertebral level does the spinal cord end?
L1-L2.
Which of the following completes the majority of the processing of the image?
A. Array processor.
B. DAS.
C. ADC.
D. Detectors.
A. Array processor.
The array processor completes the majority of the processing of the image.
Hypertrophy of the facet of the vertebrae is known as:
Spondylosis.
The MinIP is used to display:
The minimum attenuation within a voxel.
A low level of oxygen in the blood is called:
Hypoxemia.
Conversion of data into digital values is completed by the:
A. DICOM.
B. ADC.
C. DAS.
D. Array processor.
B. ADC.
The ADC converts the data into digital values, which determine the grayscale resolution
A contiguous data set means that:
There is no gap in the image data set.
Images for a CT Orbit exam should be aquired:
A. Parallel to the infraorbital meatal line.
B. Superior to the infraobital meatal line.
C. Perpendicular to the infraobital meatal line.
D. Inferior to the infraobital meatal line.
A. Parallel to the infraobital meatal line.
CTDI measures:
The dose received in a single section or slice.
Which of the following may require a pt to be at full expiration during image acquisition?
A. CT Chest high Resolution.
B. CTA Chest.
C. CT Pulmonary Angiography.
D. CT Chest.
A. CT Chest high resolution.
During the CT Chest High Resolution exam, imaging is acquired while the patient is holding their breath in both inspiration and expiration.
Which of the following is true about CT Lung Nodule?
A. It is performed with held expiration.
B. It is performed with slow, steady breathing.
C. It is performed with an increased technique.
D. It is performed with a reduced technique.
D. It is performed with a reduced technique.
CT lung nodule protocols are often performed with decreased kV and mA settings to lower the patient’s dose. The settings are based upon the patient’s weight and produce a somewhat limited study.
Which of the following may result in mis-registration of pt info?
A. Motion.
B. Partial volume averaging.
C. Tube arcing.
D. Cupping.
A. Motion.
Patient motion on the image appears as streaks, misregistration of information, blurring, or step artifact.
The accuracy of the CT number compared to the linear attenuation coefficient is:
A. Linearity.
B. Quantum mottle.
C. Uniformity.
D. Noise.
A. Linearity.
Linearity describes the accuracy of a CT number compared to the linear attenuation coefficient of the object that was imaged.
When calculating DLP, what relationship does scan length have with dose?
A. It does not play a role.
B. It is proportional.
C. It is disproportionate.
B. It is proportional.
DLP is the total amount of exposure for an exam, with consideration of the scan length. The scan length is proportional the radiation dose
Which of the following is NOT a parenteral route for medication administration?
A. Sublingual.
B. Subcutaneous.
C. Intramuscular.
D. Intrathecal.
A. Sublinqual.
Iodinated contrast media are most often injected directly into the blood intravenously for CT exams. This is considered a parenteral administration of contrast. Parenteral administration is any non oral method of administration.
Which imaging plane is parallel to the metatarsals of the foot?
A. Sagittal.
B. Coronal.
C. Direct axial.
D. Oblique axial.
D. Oblique axial.
Which process uses the entire data set for image reconstruction?
A. MPR.
B. Surface rendering.
C. Volume rendering.
D. MinIP.
C. Surface Rendering.
Volume Rendering uses the entire data set for image reconstruction. Because the entire data set is used, volume rendering creates a higher quality image.
During a CT Urinary Tract exam, pts may be imaged in the prone position to better:
Differentiate stones within the urinary tract.
When performing a CT Urinary Tract exam it may be necessary to complete an additional acquisition with the patient in the prone position which helps to differentiate stones within the urinary tract.
When possible, which of the following should be avoided during pediatric imaging?
A. Reduced kV.
B. Multiphase imaging.
C. Scanning only the area of interest.
D. Validation of clinical appropriateness.
B. Multiphase imaging.
t is important that the radiation dose for each pediatric patent is optimized so that the overall dose is minimized. Several steps that can be taken to reduce the overall dose include eliminating multiphase imaging, reducing kV and mA, and ensuring clinical appropriateness.
Which of the following phases contrast enhancement best demonstrates the renal pelvis?
A. Early arterial.
B. Late arterial.
C. Excretory.
D. Corticomedullary.
C. Excretory.
Excretory phase of enhancement occurs at least 3 minutes post administration of IV contrast. This phase is ideal for imaging the renal pelvis, ureters, and bladder.
When performing a CT Head exam, the gantry should be angled:
Parallel to the infraorbital meatal line.
Voxels that form a perfect cube are referred to as:
A. Anistoropic.
B. Isotropic.
C. MPR.
D. Pixel.
B. Isotropic.
Isotropic imaging refers to when the length, width, and height of a voxel are equal and form a perfect cube. Isotropic imaging results in images with excellent quality.
The x-ray beam utilized in MDCT is known as:
A. Electronic beam.
B. Cone beam.
C. Fan beam.
D. Pencil beam.
B. Cone beam.
The generator for the CT scanner is located in the:
Gantry