Imaging Technologies I

Question 1

Definition of pixels

Answer 1

Grid elements

Question 2

Definition of image resolution

Answer 2

Used to refer to the no of pixels along each axis

Question 3

Definition of intensity/grey scale

Answer 3

No for a pixel

Question 4

Definition of intensity/grey scale resolution

Answer 4

Image of possible intensity values

Question 5

Definition of spatial resolution

Answer 5

Measure of smallest discernible details in an image

Depends on properties of imaging devie

Question 6

Definition of pixel count

Answer 6

No of pixels along each axis

Question 7

Definition of aspect ratio

Answer 7

Ratio of its width to its height

Question 8

Definition of dynamic range

Answer 8

Range of intensity values used to display the image

Question 9

Definition of n bit image

Answer 9

2n different intensity values

Question 10

Definition of voxels

Answer 10

Pixels in 3D images

Question 11

Definition of binary values

Answer 11

Only has 2 grey values in a digital image

Question 12

Definition of fluoroscopy

Answer 12

Moving images w Xray

Question 13

What is medical imaging

What can it be used for

Answer 13

Technique and process used to create images of the human body
Studying normal populations
Treatment, selection, planning, guidance, evaluation
Scientific research
Diagnosis

Question 14

What is a digital image

Answer 14

Acquired by imaging device

Overlay grid, assign an integer to each position

Question 15

Importance of image resolution

Answer 15

Low spatial resolution, cannot resolve small structures

Low intensity resolution, cannot differentiate objects that look similar

Question 16

Images and matrices

Answer 16

Images can be conveniently represented using matrices

Question 17

Pixels and voxels

Answer 17

Many medical images are 3D
Because medical images represent real things, pixels/voxels have a size
In most cases, 2D dimensions are the same but z axis is usually larger

Question 18

Image file types

Answer 18

Many image file formats available

Use DICOM, not compressed, not lossy

Question 19

Visualisation techniques

Answer 19

Slice mode

Volume mode, involves projecting a 3D dataset onto 2D images

Question 20

3 main types of visualization techniques

Answer 20

Maximum Intensity projection, can see surfaces and internal structures
Surface rendering
Volume rendering

Question 21

Generation of Xrays

Answer 21

Ionising radiation, cause biological damage
Produced when high speed electrons strike a target material (tungsten)
Max energy of X-rays depends on electron speed (30-100KeV)

Question 22

Radiographical contrast

Answer 22

Arises due to differences in density

Question 23

5 Xray densities

Answer 23

Air
Fat
Soft tissue/water
Bone
Metal

Question 24

Detection of xrays

Answer 24

Screen film combinations
Image intensifiers
Flat panel detectors static imaging
Dynamic imaging

Question 25

Modern X-ray systems

Answer 25

Chest xrays
Portable xrays
Mobile C arm X-rays
Fixed C arm single plane
Fixed C arm bi plane
Robotic C arm single plane

Question 26

Problems with projective xrays

Answer 26

All estrutures are superimposed

Cannot know depth of objects

Question 27

CT scanners used today

Answer 27

Gen 3 of 5
Single motion, fan beam rotating detector
(single/multislice)

Question 28

Methods of scanning in CT

Answer 28

Conventional scanner
Spiral scanner
Multislice scanner

Question 29

Trends in CT

Answer 29

Faster scanning, more images/sec
Lower radiation does, less mSr
Interventional, real time imaging
Spectral, resolve xray energies
Multisource, more than 1 tube