Exam (elaborations)
COMPUTED TOMOGRAPHY (CT) - SPECIALTY EXAM QUESTIONS AND ANSWERS
- Course
- Institution
COMPUTED TOMOGRAPHY (CT) - SPECIALTY EXAM QUESTIONS AND ANSWERS
[Show more]
Content preview
COMPUTED TOMOGRAPHY (CT) -SPECIALTY EXAM QUESTIONS AND
ANSWERS
Air calibration - Answer-Scan of air in gantry; based on a known value of -1000 for air,
the scanner calibrates itself according to this density value relative to actual density
value measured.
algorithm - Answer-Mathematic formula designed for computers to carry out complex
calculations required for image reconstruction; designed for enhancement of soft tissue,
bone, and edge resolution. also referred to as kernel
anisotropic spatial resolution - Answer-spatial resolution of a voxel in which all three
axes of the volume element are not equal. slice thickness is not equal to pixel size.
aperture - Answer-opening of the gantry through which patient passes during scan
archiving - Answer-storage of CT images on long term storage device such as cassette
tape, magnetic tape, or optical disk.
artifact - Answer-distortion or error in image that is unrelated to subject being studied
attenuation - Answer-coefficient CT number assigned to measured remnant radiation
intensity after attenuation by tissue density.
axial - Answer-describes plane of image as presented by CT scan; same as transverse.
bolus - Answer-preset amount of radiopaque contrast medium injected rapidly per IV
administration to visualize high flow vascular structures, usually in conjunction with
dynamic scan; most often injected using a pressure injector.
channel - Answer-in multidectector CT, multiple rows of detectors (channels) are
arranged along the longitudinal (z) axis of the patient. each detector row(channel)
consists of numerous elements.
Computed Tomography (CT) - Answer-xray tube and detector assembly rotating 360
degrees around a specified area of the body; also called CAT (Computed Axial
Tomography)
Computed tomography dose index (CTDI) - Answer-Radiation dose descriptor
calculated with normalized beam widths for 14 contiguous sections or slices
, Computed tomography dose index 100 (CTID100) - Answer-radiation dose descriptor
calculated with the full length of a 100 mm pencil ionization chamber. Measures larger
scan distances than CTDI, but only one location is calculated.
Computed tomography dose indexvol (CTDIvol) - Answer-Radiation dose descriptor that
takes into account the parameters that are related to a specific imaging protocol.
considers helical pitch or axial scan spacing in its calculation. more accurate measure of
dose per protocol.
Computed tomography dose indexw (CTDIw) - Answer-radiation dose descriptor that
provides a weighted average of the center and peripheral contributions to dose within
the scan plane. more accurate than CTDI100 owing to calculations from more than one
location.
CT angiography - Answer-use of volumetric CT scanning with spiral technique to
acquire image data that are reconstructed into three dimensional CT angiograms.
CT number - Answer-Arbitrary number assigned by computer to indicate relative density
of a given tissue; CT number varies proportionately with tissue density; high CT
numbers indicate dense tissue, and low CT numbers indicate less dense tissue. all CT
numbers are based on the density of water, which is assigned a CT number of 0. also
referred to as a Hounsfield unit.
contrast resolution - Answer-ability to differentiate between small variations in density
within the image.
curved planar reformations - Answer-post processing technique applied to stacks of
axial image data that can be reconstructed into irregular or oblique planes
data acquisition system (DAS) - Answer-Part of detector assembly that converts analog
signals to digital signals that can be used by the CT computer.
Detector - Answer-electronic component used for radiation detection; made of either
high density photo reactive crystals or pressurized stable gases.
detector assembly - Answer-Electronic component of CT scanner that measures
remnant radiation exiting the patient, converting the radiation to an analog signal
proportionate to the radiation intensity measured.
direct coronal - Answer-Describes position used to obtain images in coronal plane; used
for head scans to provide images at right angles to axial images; patient is positioned
prone for direct coronal images and supine for reverse coronal images
Dose length product (DLP) - Answer-commonly reported dose descriptor on cT
scanners. Calculated by multiplying the CTDLvol by the length of the scan (cm).
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller biggdreamer. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $14.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
72042 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now