Introduction To Medical Imaging

Question 1

Define medical imaging.

Answer 1

Is a discipline in the healthy sector that deals with radiations to diagnose and treat disease, some radiations are x-ray, magnetic field and ultrasound

Question 2

Explain the 2 roles of medical imaging .

Answer 2

Diagnostic role/ radiography: this role helps to diagnose diseases

Therapeutic radiography/role:
This involves the treatment of diseases

Question 3

What’s the significance of radiation in medicine?

Answer 3

Radiation provides the radiographer with techniques that help to look inside the body of the body without physical cutting.

Helps radiographers to investigate disease and treat some diseases by using different radiations.

Question 4

Explain how the general x-ray machine works.

Answer 4

The General X-Ray machine.
Used special type of rays Called x-rays and the rays are made to pass through an area of focus, some rays penetrate and some are blocked forming an image in an analog format and is viewed In a viewing box.

Question 5

List the modalities used in medical imaging.

Answer 5

> X-ray equipment
Magnetic resonance imaging
Nuclear medicine equipment
Radiotherapy equipment

*There are only 4 modalities

Question 6

X-ray equipment is categorized according to it’s diagnostic roles, explain the categories.

Answer 6

1. General X-ray machine
2. Fluoroscopy machine
3. Mammography Machine
4. Bone densitometry machine
5. Mobile machine

Question 7

Who discovered x-rays

Answer 7

William Conrad Roentgen

Question 8

Explain the discovery of x-rays

Answer 8

• he was in a physics lab working on an experiment of the crooks tube
• One end of the tube was cathode and one end anode connected to a high voltage transformer.
• He switched it on and he notices that a blueish green color glowing from the tube, and he thought were cathode rays.
• He then covered the crooks tube with a black box and switched off the lights, he notices that some 8ft from where he was there was a glow of barium platinocide fluorescent material.

Question 9

When were x-rays discovered

Answer 9

8th November 1895

Question 10

First x-ray examination was taken on

Answer 10

20th December 1895 his wife’s hand

Question 11

Process in which x-rays are produced

Answer 11

Thermionic emission

Question 12

Bremsstrahlung

Answer 12

A type of electromagnetic radiation produced when an accelerating charged particle is suddenly stopped by a nucleus to produce energy photons.

Question 13

Evolution of the x-ray tube

Answer 13

1. Realignment of the cathode with anode; for the emitted electrons to be going directly to the anode.
2. Bevelling of the anode; to avoid x-rays from going different direction rather one direction.
3. Redesign the cathode from a single basic disc to a filament; to produce more electrons
4. Redesigning of the anode to make it a rotating anode; this was to prevent pitting of the anode cause by the electrons. Thereby extending the lifespan of the tube.

Question 14

Basic requirements for Production of x-rays

Answer 14

1. A vacuum( glass envelope made of borocilicate glass)
2. A source of electrons-cathode
3. A target for the electrons-anode
4. A high potential difference(voltage) between the anode and
   cathode

Question 15

Properties of x-rays

Answer 15

• travel at the speed of light
• Cannot be focused by lens
• Have short wavelength
• Have photographic effect
• Causes ionization of matter

Question 16

Electromagnetic spectrum

Answer 16

• Is the flow of energy at the universal speed of light through
space or through a material medium in the form of electric and
magnetic fields

Question 17

Types of electromagnetic radiation

Answer 17

• ionizing radiation
• Non ionizing radiation

Question 18

Ionizing radiation

Answer 18

It nocks off electrons from their orbit after an interaction

Question 19

Non-ionizing radiation

Answer 19

Does not ionize atoms after an interaction

Question 20

Forms of electromagnetic radiation

Answer 20

• GaXu-Vi-IMiRa

Question 21

Sources of ionizing radiation

Answer 21

1. Natural sources
2. Artificial sources

Question 22

Natural sources of ionizing radiation

Answer 22

• Radon Gas; decay product of uranium
• Cosmic rays; rays that exist in fast moving objects in space tend to emit radiation.
• Terrestrial radiation; radiation occurs naturally in the soil, water air
• Radiation inside the body

Question 23

Artificial sources of ionizing radiation

Answer 23

• Medical x-rays
• Nuclear power plants
• Nuclear weapons
• Consumer items e.g bricks, cement
  blocks, granite, phosphate fertilizers

Question 24

Types of ionizing radiation

Answer 24

1. Alpha particles
2. Beta particles
3. Gamma rays

Question 25

Alpha particles

Answer 25

•Alpha particles are made of 2 protons and 2 neutrons.
• This means that they have a charge of +2, and atomic mass unit
of 4.
• Alpha particles are relatively slow and heavy

Question 26

Beta particles

Answer 26

Beta particles have a charge of minus 1 (-1), and a mass of about
0.0005.
• Beta particles are the same as an electron, they are fast and light.
• Beta particles have a medium penetrating power
* they are
stopped by a sheet of aluminium or plastic such as Perspex.
• Beta particles ionize atoms that they pass, but not strongly as
alpha particles.

Question 27

Gamma rays

Answer 27

Gamma rays are waves, therefore
mass and no charge.
• Gamma rays have high penetrating power (it takes a thick sheet such
as lead, or a concrete to reduce them significantly).
• Gamma rays do not directly ionize other atoms, although they may
cause atoms to emit other particles which will then cause ionization.
• Gamma rays originate in the nucleus of an atom.

Question 28

Detail

Answer 28

The sharpness of appearance of small structures on the radiograph

Question 29

Distortion

Answer 29

Misrepresentation of anatomical structure in size and shape on the radiograph

Question 30

Image quality factors

Answer 30

• Contrast
• Optical density
• Distortion
• image detail

Question 31

Factors that are used to describe radiographic positioning and techniques.

Answer 31

1. Patient factors
2. Image quality factors
3. Exposure factors

Question 32

Patient factors

Answer 32

Evaluation of patients body size, shape and physical condition

Question 33

Body decubitus of patients

Answer 33

Sthenic; strong and active( average body)
Hyposthenic; slim but healthy in appearance
Hypersthenic; overweight individuals ( obese)
Asthenic; thin, small, frail and emaciated