CT Instrumentation part 2

Question 1

What is the word for CT that corresponds to the bore size in MR?

Answer 1

The gantry aperture

Question 2

How much can CT gantries tilt?

Answer 2

12 - 30 degrees

Question 3

What is the frequency range for the high frequency generators used in modern CT scanners?

Answer 3

500 - 25,000 Hz

Question 4

How many degrees angled is the high speed rotating anode in the CT x-ray tube?

Answer 4

12 degree target angle

Question 5

What part of the CT system has Ceramic Elements?

Answer 5

the Solid State detectors used in multi-slice CT

Question 6

What is the common name for “axial” CT image acquisition that we use here for Iaia’s head scans.

Answer 6

Step-and-shoot

Question 7

Speed and Accuracy are two important features of this “A” acronym that is part of the CT imaging system.

Answer 7

ADC (or Analog to Digital Converter)

Question 8

What is the relationship between the number of “bits” of the ADC processor and it’s accuracy?

Answer 8

The high the “bits” the more accurate the it is and the more shades of gray represented

Question 9

What is the relationship between ADC (analog to digital converter) speed and accuracy?

Answer 9

They are inversely proportional. As one increases, the other decreases (ie. increased accuracy = slower digitization)

Question 10

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)

Answer 10

Results in decreased accuracy in the digitization process

Question 11

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)

Answer 11

Detector efficiency

Question 12

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)

Answer 12

Gantry aperature

Question 13

The gantry is equipped with _____ technology for the purpose of centering and positioning the patient for a CT exam.

Answer 13

Laser Beam

Question 14

The typical range of gantry tilt in a CT scanner is ______. (1 - 5 degrees, 5 - 10 degrees, 10 - 15 degrees, 12 - 30 degrees).

Answer 14

12 - 30 degrees

Question 15

What type of detector is used in a multi-slice CT scanner? (xenon detector, flat panel detector, scintillation detector, dosimetry detector)

Answer 15

Scintillation Detector

Question 16

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)

Answer 16

Asymmetric detector

Question 17

What 3 functions does the computer system do with data?

Answer 17

Received data, reconstructs data, manipulates data (raw and image)

Question 18

CT Computers have a special processor called “LAPP”. What does it stand for?

Answer 18

Large Array Parallel Processor

Question 19

What is the main goal of pre-processing software?

Answer 19

To remove unwanted signals prior to image reconstruction

Question 20

What is the ultimate goal of the reconstruction software?

Answer 20

assigning CT Numbers

Question 21

1. 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 _______.

Answer 21

Reconstruction Algorithms

Question 22

What scanner generation were iterative reconstruction methods used?

Answer 22

First Gen

Question 23

What type of reconstruction algorithm is prone to Star Pattern Noise?

Answer 23

Back Projection

Question 24

Of the three major reconstruction algorithms, which is in use today?

Answer 24

Analytical method (filtered back projection or interpolation algorithms)

Question 25

In what kind of scaning are interpolation algorithms used?

Answer 25

Helical or Spiral scanning

Question 26

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)

Answer 26

Control Unit

Question 27

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)

Answer 27

CPU

Question 28

The industry standard format for radologic images is:

Answer 28

DICOM