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.
Which of the following is calculated by multiplying the CTDIvol and the length of the z-axis?
A. DLP.
B. CTDIW.
C. WR.
D. MSAD.
A. DLP.
All of the following would reduce patient dose in CT, except:
A. Decreasing mA.
B. Increasing pitch.
C. Using thinner slices.
D. Limiting the use of multiphase scans.
C. Using thinner slices.
A single voxel may encompass more than one tissue type, in which case the system uses _______ to assign the voxel a single CT number.
Partial volume averaging.
An __________ occurs when an inner layer of the aorta tears and a false lumen is created.
Aortic dissection.
High resolution CT imaging of the lungs uses all of the following, except:
A. Reduced kVp.
B. Reconstruction with high spatial frequency.
C. Reduced DFOV to include only lung parenchyma.
D. Thin slice acquisition.
A. Reduced kVp.
An environment from which all microorganisms have been removed or destroyed is:
Sterile.
Which of the following exams may require two acquisitions with the patient’s mouth open and then closed?
TMJ.
The human eye can differentiate ____ shades of gray.
60 to 80.
The range of displayed pixel values is decided by the selected:
Window width (WW).
A technologist performing a CT exam could choose to increase the pitch because:
increasing pitch = decreases dose.
When imaging the eye orbits, axial images are obtained parallel to the:
Infraorbitomeatal line (IOML).
The _______ provides specific education to parents, technologists, and radiologists on reducing pediatric CT doses.
Image Gently Campaign.
What type of contrast media contains molecules which dissociate into ions in solution?
Ionic.
The double-walled serous membrane surrounding the abdominal organs forms the:
Peritoneal cavity.
Which phase of contrast enhancement is marked by enhancement of venous structures?
Non-equillibrium Phase.
The section interval is the:
Space between each slice, section, or image.
In CT exams of the chest, pitch must be adjusted based on the:
Patient’s ability to hold-respiration.
Automatic Tube Current Modulation (ATCM) adjusts the ______ setting for maximum image quality with minimum patient dose.
mA.
A newer type of reconstruction method which uses the shapes of the primary and remnant beams to generate an image with reduced noise is called:
Model-based iterative reconstruction.
Visualization of the tracheobronchial tree using 3D images and reconstruction is called:
Bronchography.
The mathematical process in which the ray sum data from a scan is transformed into a matrix is called:
Back projection.
The number of photons passing through an area in a unit of time is the:
Photon flux.
A large blood clot located in the pulmonary trunk where it bifurcates into the left and right pulmonary arteries is called:
Saddle PE.
All of the following are used to increase tube heat dissipation efficiency, except:
A. oil and air cooling.
B. increased anode diameter.
C. conduction by tube rotation.
D. decreased filament sizes.
D. decreased filament sizes.
________ is a narrowing of the bony canals that contain the spinal cord and nerve roots.
Spinal stenosis.
Which of the following interactions occurs when an x-ray photon interacts with and ejects an outer shell electron?
Compton scattering.
The ECG gating technique that scans throughout the entire cardiac cycle and then allows the user to select data for reconstruction is called:
Retrospective gating.
The use of complex voltage-switching to create images of varying attenuations is called:
Dual-energy CT.
Manufacturers use the ____ when reporting typical CT scanner doses to the U.S. Food and Drug Administration.
CTDI.
All of the following would increase patient dose during a CT exam, except:
A. using thinner slices.
B. performing multiphase exams.
C. adjusting mA based on pt size.
D. incrasing kVp.
C. adjusting mA based on pt size.
Adjusting mAs based on patient’s size is a strategy for reducing radiation dose in CT.
Which of the following CT systems does not use moving parts?
A. MDCT.
B. SSCT.
C. Dual-energy MDCT.
D. Electron beam CT.
D. Electron beam CT.
Barium sulfate is contraindicated as an oral contrast in cases of:
Bowel Perforation.
Which of the following patient instructions during acquisition would improve visualization of the vocal cords?
Suspended respiration.
To reduce streak artifacts:
A. increase kVp.
B. decrease kVp.
C. increase mAs.
D. Decrease mAs.
A. Increase kVp.
Which of these structures lies between the pubic symphysis and rectum, just inferior to the base of the bladder?
A. Spleen.
B. Prostate.
C. Sigmoid colon.
D. Testes.
B. Prostate.
What is the SI unit of absorbed dose?
Gray.
Dual-energy CT scanning relies on:
Applying two different kVp settings during a scan.
The factor that limits how narrow a slice can be in MDCT is:
Detector configuration.
Which of the following window levels and widths would best display bone in an orbit exam?
WL 400; WW 3000.
CT enteroclysis uses a(n):
NG Tube.
The quantity of information that can be contained within each pixel is the:
Bit Depth.
Which of the following CT detector configurations allows for the most rapid acquisition time?
A. 32 rows x 0.5 mm per row.
B. 16 rows x 1.0 mm per row.
C. 64 rows x 0.625 mm per row.
D. 16 rows x 1.25 mm per row.
C. 64 rows x 0.625 mm per row.
Which of the following image production processes is performed by the host computer of the CT system?
A. creation of unprocessed transmission readings.
B. creation of analog electrical singals.
C. creation of digitized attenuation measurements.
D. creation of multiplanar reformations.
D. creation of multiplanar reformations.
A CT imaging of the lungs demonstrates a hyperdense area of inflammation with an irregular border? What is the diagnosis?
A. Pulmonary metastases.
B. Pneumonia.
C. Interstitial lung disease.
D. Pneumothorax.
E. Pleural Effusion.
B. Pneumonia.
Why is the range of imaging limited in the shuttle/continuous/cine data acquisition mode in CT?
The pt’s table moves rapidly back & forth.
In CT imaging, the primary purpose of adjusting the collimation is to control the:
A. Level of noise in the image.
B. Patient dose.
C. Contrast resolution.
D. Spatial resolution.
D. Spatial resolution.
Excessive production of sex-related hormones could be caused by a neoplastic condition in what organ?
Adrenal Gland.
During CT venography of the head, the purpose of scanning in the direction of superior to inferior is to:
Follow the flow of contrast through the cerebral sinuses.
CT systems distinguish between different types of tissues in the pts body by detecting the intensity of which of the following?
A. Primary radiation.
B. Remnant radiation.
C. Scatter radiation.
D. Characteristic radiation.
B. Remnant radiation.
What reconstruction parameters should be used for 3D renderings of the colon in CT colonography?
1.25 mm slice thickness in the standard algorithm.
Acquisition slice thickness is directly determined by the:
Detector row thickness.
A technologist attempts and fails to cannulize (insert the tube) the cephalic vein in mid-forearm. What sites are appropriate to cannulize on the 2nd attempt?
Basilic vein distal to the initial site.
Basilic vein proximal to the initial site.
Cephalic vein proximal to the initial site.
(Tech can NOT use the same vein more than once!)
What data acquisition method uses the concept of pitch to manage the balance between image quality & radiation dose?
Helical.
What pulmonary condition typically presents in sectional imaging as a single neoplasm with a thick, irregular border?
Bronchogenic carcinoma.
What type of photon-tissue interaction is responsible for the majority of the contrast in CT imaging?
Photoelectric effect.
The MIP rendering technique is LESS suitable in CT imaging when imaging which of the following structures?
A. Blood vessels.
B. Bones.
C. Soft tissues.
D. Heart.
C. Soft Tissues.
A CT scan of a pt with severe facial trauma reveals a suspected mandibular fracture. What signs on a CT scan would most likely support this diagnosis?
A. Increased maxillary sinus deformity.
B. Discontinuity in the mandibular cortex.
C. Enlargement of the temporomandibular joint.
D. Widening of the nasal septum.
B. discontinuity in the mandibular cortex.
What is the resulting effect when the pitch is increased in CT imaging?
A. increased amount of overlap.
B. decreased amount of overlap.
C. Increasing pitch has no effect on the amount of overlap.
B. decreased amount of overlap.
What 3 imaging quality factors are affected by changes to the reconstruction thickness in CT?
- Spatial resolution.
- Contrast resolution.
- Noise.
The primary benefit of integrating Medical Image Management and Processing System (MIMPS) with the Electronic Medical Record (EMR) is that it:
Allows for more convenient retrieval & viewing of images within a pt’s health record.
Contrast resolution in CT imaging refers to the ability of the system to:
Differentiate between objects with similar attenuation properties.
What term describes a benign vascular malformation within the liver?
Liver hemangioma.
Which of the following image production processes is performed by the array processor of the CT system?
A. creation of unprocessed transmission readings.
B. creation of analog electrical signals.
C. creation of digitized attenuation measurements.
D. creation of reconstructed image data.
D. creation of reconstructed image data.
How should gonadal shielding be applied to a female pediatric pt undergoing a CT examination of the pelvis for appendicitis?
Gonadal shielding should NOT be used.
What effect does decreasing the DFOV have on the pixel size in CT imaging?
Decreasing DFOV = Decreases the pixel size = improves image detail.
In what scenario would a cone beam artifact be most severe?
Using a wide detector array scanner for volumetric CT imaging.
Which CT image artifact arise from abrupt changes in tissue density?
Edge gradient artifact.
Which of the following pathologies develops from malignant cells that have migrated to the brain from a primary cancer elsewhere in the body?
- Pituitary adenoma.
- Meningioma.
- Medulloblastoma.
- Acoustic neuroma.
- Cerebral metastases.
- Cerebral metastases.
Decreasing the window level (WL) affects the appearance of a CT image by:
Increasing image brightness.
Which of the following vessels is a primary source of blood supply to the upper extremity?
A. Femoral artery.
B. Vertebral artery.
C. Subclavian artery.
D. Carotid artery.
C. Subclavian artery.
A pt with suspected cervical spondylosis is scheduled for a CT scan. What imaging plane is typically used to best visualize this condition?
Sagittal.
What is the most suitable window setting for evaluating the thoracic spinal cord on a CT scan?
Soft tissue window.
- best to see the soft tissues and spinal cord.
How does the osmolality of non-ionic contrast media compare to ionic contrast media?
Non-ionic contrast media has a LOWER osmolality than ionic contrast media.
Which of the following changes can be implemented to decrease the appearance of noise in a CT image?
A. decrease tube current (mA).
B. decrease tube potential (kVp).
C. use of an edge-enhancing algorithm.
D. use of a smoothing algorithm.
D. use of a smoothing algorithm.
Which of the following CT data acquisition methods is best suited for imaging large anatomical areas in one rotation of the gantry?
A. Axial/sequential.
B. Helical.
C. Volumetric.
D. Dual-energy/dual-source.
C. Volumetric.
What landmark is commonly used to identify the bladder on a CT scan?
Symphysis pubis.
Which of the following can cause ring artifacts in CT?
A. Non-uniform detector responses.
B. Pt movement during the helical exposure.
C. Positioning the pt outside the SFOV.
D. Temporary loss of x-ray tube output.
A. Non-uniform detector responses.
What reconstruction protocol will produce minimal image noise for CT imaging of the soft tissue neck?
A. 0.5 mm reconstruction thickness in the bone algorithm.
B. 0.5 mm reconstruction thickness in the standard algorithm.
C. 3.0 mm reconstruction thickness in the bone algorithm.
D. 3.0 mm reconstruction thickness in the standard algorithm.
D. 3.0 mm reconstruction thickness in the standard algorithm.
Which of the following demonstrate implied consent in CT? (Select 2).
- a pt arrives for an abdominal CT.
- a pt signs a pregnancy consent for a pelvic CT.
- a pt lies down on the CT scanning bed in preparation for a head CT.
- a pt’s family member gives verbal permission for a CT-guided biopsy.
1 and 3.
What is the primary pathological consideration in soft tissue neck CT imaging when a pt presents with a malignant neck mass?
A. Hemangioma.
B. Thyroid adenoma.
C. Squamous cell carcinoma.
D. Branchial cleft cyst.
C. Squamous cell carcinoma.
In CT imaging of the sacrum/coccyx, what type of post-processing presentation is typically used to best depict the anatomy?
- MIP.
- Volume rendering (VR).
- MPR.
- Surface rendering.
Multiplanar Reconstruction (MPR).
How does the normal density of the spleen compare to the normal density of the liver during the portal venous phase of IV contrast enhancement?
The spleen is isodense compared to the liver.
- Isodense = same density.
What scan delay time will demonstrate the pancreas in the portal venous phase of contrast enhancement?
A. 30 seconds.
B. 70 seconds.
C. 3 minutes.
D. 5 minutes.
B. 70 seconds.
What is the primary advantage of computed tomography venography (CTV) over ultrasound for evaluating venous anatomy & pathology in the neck region?
A. CT venography provides real-time imaging.
B. CT venography provides higher spatial resolution.
C. CT venography is less invasive.
D. CT venography is faster.
B. CT venography provides higher spatial resolution.
Which of the following image analysis tools are used in CT to measure the depth of a tumor relative to the surface of the pts skin?
A. Region of interest (ROI).
B. Standard deviation (SD).
C. Histogram analysis.
D. Geometric distance.
D. Geometric distance.
How is multiplanar reformation (MPR) utilized in the assessment of diseases such as cancer?
MPR enables the visualization of the disease from multiple angles.
Uniformity in a CT image refers to the consistency of:
CT numbers for the same material throughout the image.
The mathematical process that allows multidetector ct (MDCT) images to be reconstructed at any point along the acquired volume is commonly known as:
Z-filtering
A CT image is formed in part by projecting back all of the attenuation values recorded during data acquisition onto a:
MATRIX
Filament sizes for modern ct xray tubes range between:
0.5 and 1.2 mm
The average density of a mass within the kidney measures -75 HU. The mass is most likely a:
LIPOMA
The benign mass of the 8th cranial nerve known as vestibular schwannoma may also be termed a(n):
Acoustic neuroma
Equation for Lambert-Beer law
I=Ioe^-ux
Equation for Lambert-Beer law
I=Ioe^-ux
In the binary number system, a byte is a series of ______ bits of information
Eight (8)
Areas of a CT image that contain minimal changes in tissue density are electronically represented by:
Low spatial frequencies
Writable CD and DVD media are optical disks that may be described as:
Write-once, read-many (WORM)
Compared with conventional radiography, CT produces diagnostic images with better;
Low-contrast resolution
What term describes the interaction between high-energy electrons & the nuclei of the target material that results in the production of xrays?
Bremsstrahlung radiation.
Which liver tumor becomes iso-intense or hyper-intense relative to the surrounding liver tissue during delayed imaging in CT?
Liver hemangioma
