Module 1

Question 1

Allows the superimposition structure to be lurred and thus leaving the area of interest in maximum focus.

Answer 1

Axial tomography

Question 2

Axial tomography is also called

Answer 2

Conventional tomography

Question 3

2 types of axial tomography

Answer 3

sagittal and coronal

Question 4

hounsfield unit also reffered to as

Answer 4

ct number

Question 5

Goals of CT:

Answer 5

Overcome superimposition if structures
Improve image contrast
Measure small differences in tissue contrast

Question 6

1st mathematically principle developed
It is possible to build up an image of two or three dimensional object from a large number of projections from different directions.

Answer 6

1917 by J. Radon

Question 7

cross section portion of body scanned is called

Answer 7

slice/ cut

Question 8

two dimensional array of numbers arranged in rows and columns is called

Answer 8

Matrix

Question 9

Each square in matrix is called

Answer 9

Pixel or picture element

Question 10

3D
represents tiny block of tissue called

Answer 10

voxel

Question 11

numbers in the image matrix is called

Answer 11

ct number or hounsfield unit

Question 12

restricts xray beam to specific area
controls slice thickness
reduce pt dose
improve image quality

Answer 12

Functions of Collimator

Question 13

Advantage of this CT detector is to remain stable under pressure, cheaper, and easier to calibrate.
Can be used in third gen scanner.
60 - 87% absorption

Answer 13

Xenon gas detector

Question 14

This gas must be kept under pressure in an aluminum casing

Answer 14

Xenon gas

Question 15

Advantage of this CT detector is it has a high coefficient of 100%

Answer 15

Solid state crystal (Scintillation Detectors)

Question 16

determines the radiation dose profile & pt radiation dose

Answer 16

Prepatient Collimator

Question 17

determines the sensitivity profile & improves contrast

Answer 17

Postpatient/ Predetector Collimator

Question 18

captures radiation beam from the patient & converts it into electrixal signals then be converted into binary information

Answer 18

CT Detector

Question 19

Causes of ring artifacts

Answer 19

single detector
multiple detector
malfunction

Question 20

The smaller the pixel size, the better the:

Answer 20

spatial resolution

Question 21

Factors affecting Noise:

Answer 21

kVp & Filtration
Pixel size
Slice thickness
Detector efficiency
Pt dose

Question 22

describes the amount of the CT number of a material is exactly proportional to the density of this material
must be calibrated frequently so that water is consistently represented by CT number 0

Answer 22

Linearity

Question 23

EMI Mark 1

Answer 23

1st Generation Scanner

Question 24

T/F
5th generation scanner uses translate-rotate principle

Answer 24

F
1st & 2nd generation

Question 25

for head ct scan only because abdomen or chest has motion

Answer 25

1st Generation

Question 26

more throughput, more information can be scanned 20 second image acquisition able to rotate at 6°

Answer 26

2nd Generation

Question 27

complete rotation of XRT and detectors scan time about .5 seconds or less

Answer 27

3rd Generation

Question 28

complete rotation of XRT around stationary detectors ring fan beam geometry

Answer 28

4th Generation

Question 29

no XRT uses electron gun EBCT & DSR

Answer 29

5th Generation

Question 30

DSCT Scanner Image moving structures such as heart Minimize motion artifacts Have multiple XRT and detectors

Answer 30

6th Generation

Question 31

number of line pairs per unit length is called

Answer 31

spatial frequency

Question 32

1 bar & its interspace of equal width

Answer 32

line pair

Question 33

Factors affecting Image Quality

Answer 33

Spatial resolution Contrast resolution Temporal resolution Noise

Question 34

degree of blur or the ability to see the difference between two objects that are close together

Answer 34

Spatial resolution

Question 35

ability to differentiate between small differences in density within the image

Answer 35

contrast resolution

Question 36

Factors that improve Temporal resolution

Answer 36

Multidetector Tube/Gantry rotation time Dual source CT

Question 37

good for cardiac CT freeze any motion of a scanned object

Answer 37

Temporal resolution

Question 38

scan parameters affecting contrast

Answer 38

slice thickness reconstruction algorithm image display (window width)

Question 39

scan parameters affecting spatial

Answer 39

SFOV DFOV Matrix Reconstruction slice thickness Detector aperture width Slice thickness

Question 40

made of carbon filter strong, rigid doesn't absorbs xrays coming from pt

Answer 40

patient couch/table

Question 41

quick heat transfer but heavy

Answer 41

all metal disk design

Question 42

base body is graphite high heat storage capacity and faster anode cooling

Answer 42

brazed graphite anode disk

Question 43

can accommodate large, lightweight disks with large heat storage capacity and fast cooling rates

Answer 43

chemical vapor deposition graphite disk

Question 44

removes long wavelengths xrays shapes the energy distribution across the radiation beam by using shaped filter

Answer 44

Filtration

Question 45

residual gas molecules present within the evacuated envelope

Answer 45

tube arcing

Question 46

topography

Answer 46

Allesandro Volta

Question 47

made many advances in rotational scanning

Answer 47

David E. Kuhl & Roy Q. Edwards

Question 48

derived a mathematical theory for image reconstruction he also applied reconstruction technique in NucMed

Answer 48

Allan Mcleod Cormack

Question 49

inventor of clinical Computed tomography

Answer 49

Godfrey Hounsfiled 1967

Question 50

obtained readings from a specimen of Human brain

Answer 50

James Ambrose 1971

Question 51

1st whole body ct scanner

Answer 51

Robert Ledley 1974

Question 52

Major limitation of Radiography

Answer 52

Superimposition of anatomical structure Radiography is qualitative rather than quantitative

Question 53

reduction of energy of xrays

Answer 53

attenuation