Display

Hard copy

Radiographic film or digital images produced using laser printers or dry processors, and is displayed on an illumination viewbox

Soft copy

The images are viewed on a screen flat monitor

1. Multiple viewing of the same image

2. Variation of image display parameters

3. Reduced number of lost films

4. Can be displayed and distributed throughout different locations simultaneously

5. Manipulate images directly on a monitor without re-exposing the patient

Advantages of digital, image display:

Teleradiology

Is the practice in which radiologists remotely read examinations results and write reports

Hardware components

The physical parts of your computer system that can be

touched. It also enables data entry, processing, storage, and

the output of data processing

Software components

responsible for the digital instructions and programs

that enable the hardware to function individually and

communicate collectively

- Input

- Processor

- Memory

- Output devices

Core hardware components of the computer:

Input hardware

... converts data into a form that the computer can use

Output hardware

Consists of devices that translate computer information into a form that humans can understand

Flat panel displays or Display monitors

Are the most prevalent form of display in radiology departments today

- Cathode ray tube monitors (CRT)

- Liquid crystal display monitors (LCD)

Types of Display monitors:

Cathode ray tube monitors

It is a vacuum tube that is used as a display screen in a computer or video display terminal

Cathode ray tube monitors

They are thicker in size than LED and LCD, requiring more space on desks and counters

Cathode ray tube monitors (CRT)

This monitor produces a very bright image and has a very fast refresh

rate, which reduces the possibility of blur

- energy consumption

- heat production

- sheer size and weight of the monitors

Biggest disadvantage of cathode ray tube monitors:

1. Cathode

2. Conductive Coating

3. Anode

4. Phosphor-Coated Screen

5. Electron Beams

6. Shadow Mask

Components of a cathode ray tube monitors:

Refresh rate

Is the measure of how fast the monitor rewrites the screen or the number of times that the image is redrawing on the display each second

Hertz

Refresh rate is measured in ...

Dot pitch

Is the measurement of how close the dots are located to one another within a pixel

Finer

The smaller the dot pitch, the ... the resolution

Millimeters

Dot pitch is usually expressed in ...

Shadow mask

Metal plates with holes in them, ensure that each electron beam only reaches its correct

color phosphor

Liquid crystal display (LCD) monitor

produces images by shining or reflecting

light through a layer of liquid crystal and a series of color filters

liquid crystal display (LCD) monitor

Monitor mostly prevalent in all radiology departments

1. Case

2. Backlight

3. 2 Polarized filters

4. Thin film transistor (TFT)

5. Liquid crystal

6. Color filters

7. Cover glass

Components of an LCD monitor:

1. Backlight

2. Liquid crystal layer

3. Color filters

Three main components of every LCD:

Backlight

LCD: a big panel of bright white lights that is usually composed of

light-emitting diodes (LED)

Polarized filters

LCD: Control the intensity and color of the transmitted light from the backlight

Polarized filters

LCD: sandwiches the liquid crystal layer of the LCD panel

Liquid crystal

LCD: Is a material state between that of a liquid and solid

1. Nematic

2. Smectic

Liquid crystal has two phases:

Red-green-blue

Color LCDs have ... filters fashioned into the pixels to create colors; turning the white light into millions of different shades

1. Twisted Nematic Panels

2. Vertical Alignment Panels

3. In-Plane Switching Panels

Three Major Categories for LCD Display Panels:

Twisted nematic panels

These are the oldest, most common LCD screen type, and simplest of the three

Twisted, untwist

TN Panel: In their default state, the crystals are ..., when Voltage is applied, they ... to block light

Fast response rate for dynamic images, reducing the chance of blur

Advantages of Twisted Nematic Panel:

- The viewing angle of the display

- The ability to produce a wide range of colors

Disadvantages of Twisted Nematic Panel:

Vertical Alignment Panel

These were designed to solve contrast issues of the TN LCD panels

vertically, tilt

VA panel: When no voltage is applied, the liquid crystals sit ...,

When voltage is applied, crystals start to "..." over to let light through

- Will produce blacker blacks

- Can produce 10-bit images

- Allows greater viewing angle

- Functions in more extreme temperature variations

Advantages of Vertical Alignment Panel:

- Much more expensive than TN panel

Disadvantage of Vertical Alignment Panel:

In-Plane Switching Panel

It is superior in color reproduction and greater viewing angle, but offers a slightly lower refresh rate than TN displays

rotate parallel ("in-plane")

IPS Panel: When voltage is applied, the crystals ...

("...") rather than upright to allow light to pass through

Angular dependence of viewing

Principal disadvantage of an LCD:

- Resolution

- Luminance

- Contrast

- Bit depth

- Uniformity

- Glare

Factors affecting image quality on a monitor:

Resolution

based on how many pixels can be displayed in the

horizontal and vertical dimensions

Directly proportional

Relationship of pixel number and resolution

Luminance

It is a measure of the brightness of a source, such as a digital display device

Contrast

It is a function of luminance, and must have adequate

amounts of light from all areas

Bit Depth

The size of an image file will depend on the matrix size and bit depth

Uniformity

It measures whether the brightness and color are the same across the entire screen (vignetting effect)

Vignetting effect

Blackening on the sides, brighter center

Glare

Monitors have design features to reduce this effect; however,

it cannot be eliminated

Glare

The use of LCD monitors should not be used in rooms with ambient or bright lighting because it will cause ...