CT Instrumentation part 2 Flashcards
What is the word for CT that corresponds to the bore size in MR?
The gantry aperture
How much can CT gantries tilt?
12 - 30 degrees
What is the frequency range for the high frequency generators used in modern CT scanners?
500 - 25,000 Hz
How many degrees angled is the high speed rotating anode in the CT x-ray tube?
12 degree target angle
What part of the CT system has Ceramic Elements?
the Solid State detectors used in multi-slice CT
What is the common name for “axial” CT image acquisition that we use here for Iaia’s head scans.
Step-and-shoot
Speed and Accuracy are two important features of this “A” acronym that is part of the CT imaging system.
ADC (or Analog to Digital Converter)
What is the relationship between the number of “bits” of the ADC processor and it’s accuracy?
The high the “bits” the more accurate the it is and the more shades of gray represented
What is the relationship between ADC (analog to digital converter) speed and accuracy?
They are inversely proportional. As one increases, the other decreases (ie. increased accuracy = slower digitization)
Increased ADC speed (results in slower digitization, results in increased accuracy in the digitization process, results in decreased accuracy in the digitization process, requires a fewer bit processor)
Results in decreased accuracy in the digitization process
The ability of a detector to capture, absorb, and convert photons is referred to as: (detector response time, detector stability, the dynamic range of the detector, detector efficiency)
Detector efficiency
The circular opening of the gantry through which the patient travels in a CT scanner is termed: (gantry collimator, gantry aperature, gantry tilt, gantry range)
Gantry aperature
The gantry is equipped with _____ technology for the purpose of centering and positioning the patient for a CT exam.
Laser Beam
The typical range of gantry tilt in a CT scanner is ______. (1 - 5 degrees, 5 - 10 degrees, 10 - 15 degrees, 12 - 30 degrees).
12 - 30 degrees
What type of detector is used in a multi-slice CT scanner? (xenon detector, flat panel detector, scintillation detector, dosimetry detector)
Scintillation Detector
The type of multi-slice detector called an adaptive array in which the individual detector cells are divided into different sizes is called: (xenon detector, symmetric detector, matrix detector, asymmetric detector)
Asymmetric detector
What 3 functions does the computer system do with data?
Received data, reconstructs data, manipulates data (raw and image)
CT Computers have a special processor called “LAPP”. What does it stand for?
Large Array Parallel Processor
What is the main goal of pre-processing software?
To remove unwanted signals prior to image reconstruction
What is the ultimate goal of the reconstruction software?
assigning CT Numbers
- Iterative Methods (Algebraic Reconstruction Technique [ART] used by Hounsfield, Iterative Least Squares [ILST], Simultaneous Iterative Reconstruction Technique), 2. Back Projection, 3. Analytical Method (filtered Back Projection, Two-dimensional Fourier Transformation) are the three main kinds of _______.
Reconstruction Algorithms
What scanner generation were iterative reconstruction methods used?
First Gen
What type of reconstruction algorithm is prone to Star Pattern Noise?
Back Projection
Of the three major reconstruction algorithms, which is in use today?
Analytical method (filtered back projection or interpolation algorithms)
In what kind of scaning are interpolation algorithms used?
Helical or Spiral scanning
The part of the central processing unit that directs the activities of the computer is called the: (arithetic unit, control unit, input unit, logic unit)
Control Unit
The part of a computer system that is the center of all activities or “the thinker” is called the: (CPU, ALU, Control unit, Output Unit)
CPU
The industry standard format for radologic images is:
DICOM
