Diagnostic Technology

Question 1

What EMR is used in radiography?

Answer 1

x-ray

Question 2

When are grids used?

What is the purpose of the Grid?

Answer 2

used when the patient is more than 10 cm thick

intercepts scatter from the patient before it reaches the film

Question 3

Digital Radiography

Answer 3

The map of x-ray transmission through the patient is converted to a digital file not recorded on film.

Question 4

How is the total pixels worked out?

Answer 4

Each row x Column intersection

Question 5

What does DICOM mean?

Answer 5

Digital Imaging Communications in Medicine

Question 6

More pixels =

Answer 6

bigger file size
greater detail
The pixels are arranged in a grid called a matrix

Question 7

DR

Answer 7

Digital Radiography

Question 8

CR

Answer 8

Computed Radiography

Question 9

DDR

Answer 9

Direct Digital Radiography

Question 10

What are the types of Flat Panels?

Answer 10

Indirect Digital Detector

Direct Digital Detector

Question 11

What are the advantages of Digital?

Answer 11

Professional image
No darkroom, film, envelope

Post Processing
Consultation
Exposure Latitude
Contrast optimization

Question 12

Exposure latitude meaning?

Answer 12

the extent to which a film, image plate or film panel can be over or underexposed and still achieve an acceptable result

Question 13

Contrast Optimization meaning?

Answer 13

Application of additional processing ‘normalizes’ the image

Dark regions are made lighter and lighter regions darker

Question 14

What are the two problems we are reducing by using Digital Radiography?

Answer 14

Improper exposure

Poor darkroom technique

Question 15

ALARA

Answer 15

As Low As Reasonably Achievable

Question 16

mA

Answer 16

controls the current that goes through the filament and the hotter the filament gets the more electrons are generated

Question 17

Increasing kVp

Answer 17

Greater voltage difference
Electrons travel faster
Have more kinetic energy
Create higher energy x rays

Question 18

Underexposed image is?

Answer 18

too light

Question 19

Overexposed image is?

Answer 19

too dark

Question 20

How do you fix an underexposed radiograph?

Answer 20

Increase mAs
or
Increase kVp

Question 21

Thorax Radiographs

Answer 21

Air provides contrast

Use high kVp, low mAs

Question 22

Abdomen Radiographs

Answer 22

Fat provides contrast

Use low kVp, high mAs

Question 23

What are the advantages to using an intensifying screen?

Answer 23

Permit over 100x reduction in mAs compared to no screens
Reduced movement artifact

Reduced patient exposure
Reduced personnel exposure
Increased tube life

Question 24

What is the intensifying screen used for?

Answer 24

converts x-ray photons to light photons

Question 25

How does the scintillation layer work?

Answer 25

After the x-rays leave the patient it goes to what is known as the Scintillation layer (usually Gadolinium oxysulfide aka GOS) it interacts with the scintillation layer and becomes light. The xrays raises the electrons to a higher binding energy and when they come back down the difference in binding energies is given out as light.

Question 26

What is penumbra?

Answer 26

Penumbra is the term used when the image becomes blurred due to the x-rays not being fine and overlapping

Question 27

How does AED work?

Answer 27

``` Hollow cell containing air Air becomes ionised when exposed Creates an electrical charge which is directly proportion to the amount of radiation When Optimal charge/density is reached Exposure terminated ```

Question 28

How does CR work? overview

Answer 28

X-ray photons > Storage Phosphor > Read by Laser – releases light > Converted to Digital Data (ADC) > Image Constructed

Question 29

What is pixel depth?

Answer 29

Pixel depth is the number of bits used to define each pixel | The greater the bit depth the greater the number of shades of grey that can be represented

Question 30

How does DR (indirect) work? overview

Answer 30

X-ray photons > Light Photons > Electric Signal > Converted to Digital Data (ADC) > Image Constructed

Question 31

How does DDR work? overview?

Answer 31

X-ray photons > Electric Signal> Converted to Digital Data (ADC) > Image Constructed

Question 32

How does indirect DR work? overview

Answer 32

X-ray photons > Light Photons > Electric Signal > Converted to Digital Data (ADC) > Image Constructed

Question 33

What causes image noise?

Answer 33

Insufficient data

Question 34

What is the production source?

Answer 34

Thermionic emission, | Electrons are "burnt off" the cathode and accurate to the anode to interact with the target material.

Question 35

``` DAP apparatus What does DAP mean? Where is it located? What is it measuring? What is it measured in? ```

Answer 35

Dose Area Product Attached to the bottom of the light beam collimator Measures the patient dose received mGy.Cm2

Question 36

With reference to a detector: Indirect

Answer 36

First, the emergent beam exits the patient and reacts with the scintillator layer, this works by the Xrays interacting with the material and raising the electrons to a higher binding energy level and when the reaction is finished the electron drops back down and the difference in binding energies is given out as light. However, since the light spreads out there is also usually a crystal structure grown in columns so that the light doesn't spread out. This helps prevent low spatial resolution. Then the light interacts with a photodiode this is to turn the light into an electric signal. This means that a TFT is used in order to use the electric signal and make it digital. A TFT array means that each pixel has a capacitor and it stores an electrical charge and this turns the information into binary so that a computer can display the image.