Exam (elaborations)
Computed Tomography questions and 100% correct answers.
- Course
- Institution
Computed Tomography questions and 100% correct answers.
[Show more]
Seller
Follow
Content preview
Computed Tomography questions and100% correct answers.
Fundamentals of CT ANS - -Creating a cross-sectional tomographic place of any body part
-A patient is scanned by an x-ray tube rotating around the body
-A detector assembly measures the radiation exiting the patient.
Radiographic Tomosynthesis ANS - Uses an x-ray beam to produce multiple digital images.
What does Tomo mean? ANS - image// to long axis of the body
What does CT mean? ANS - Image is transverse to the body
-Computed Tomography
*The CT image is a transaxial or transverse image that is perpendicular to the long axis of the body.
CT Imaging System ANS - CT imaging system consists of a finely collimated x-ray beam and a single
detector; both moving synchronously in a translate rotate mode.
Translation ANS - One rotation of source and detector around the body
Projection ANS - Attenuation pattern and intensity profile is formed for that translation.
When was CT first demonstrated? ANS - in 1970, dedicated to head CT only; Dr. Godfrey Hounsfield,
Allan Macleod Cormack
When was the first full-scale commercial unit installed? ANS - 1971; Physicians recognized its value for
providing diagnostic neurologic information; these early units were also dedicated head CT scanners
When was the first whole-body scanner developed? ANS - 1974; Dr. Robert S Ledley
, First Generation Scanners ANS - -Translation/Rotation
-Tube produced a finely collimated beam or pencil beam
-1 to 3 detectors were placed opposite the tube for radiation detection
-Tube required 180 translations with 1 degree rotation
What is the downfall to first generation scanners? ANS - It takes 5 minutes to gather enough
information for one image
Second Generation Scanners ANS - -Fan shaped x-ray beam
-5 to 30 detectors
-20 seconds per slice or 10 minutes for a 40 slice exam
-10 degree rotation increments, 18 translations for 180 degree image acquisition
-Long data reconstruction time
Disadvantage of the Fan beam in a second generation scanner ANS - Increased radiation intensity that
occurs towards the edges of the beam because of body shape
-Compensated for by using a "bowtie" filter
Third Generation Scanner ANS - *Fan beam
*Multiple detectors along an arc
*The tube/detector assembley rotates around the patient
*Total scan time faster than 1 second per image
*Uses a curvilinear detector
Disadvantage of the Third Generation Scanner ANS - Ring artifacts from detector malfunction
Fourth Generation Scanner ANS - -Fixed ring of as many as 4,000 detectors, completely surrounding the
patient, rotate only movement
-Rotating x-ray tube provides short burst of radiation
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 Professorkaylee. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $9.29. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
78075 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now