RT212 Display

Hard Copy

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

Soft Copy

The images are viewed on a flat

screen monitor

1.Multiple viewing of the sameimage

2.Variation of image display parameters

3.Reduced number oflost films

4.Can be displayed and distributed throughout different locations simultaneously

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

advantages pf digital imaged display:

Teleradiology

is the practice in which radiologists remotely read examination results and write reports.

Input hardware

converts data into a form that the computer can use.

keyboard

mouse

other input

input hardware:

output hardware

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

display screens and printers

common output devices are:

monitor

printer

speaker

other output

output hardware:

Flat panel displays

are the most prevalent form of display in radiology departments today

lower resolution may be

acceptable

Monitor characteristics are determined by the requirements ofthe user: technologists

ower resolution may be acceptable for image viewing

Highest spatial and contrast resolution

for image interpretation and diagnosi

Monitor characteristics are determined by the

requirements ofthe user: radiologists

Cathode Ray Tube Monitors

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

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

energy consumption

heat production

sheer size

weight of the monitors

producing a very bright image

very fast refresh rate

disadvantages of cathode ray tubes:

Cathode

Phosphor-coated screen

Conductive coating

Electron beams

Anode

Shadow mask

cathode ray tube monitors:

refresh rate

is the measure of how fast the monitor rewrites the screen or the number oftimes that the image is redrawn on the display each second

dot pitch

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

finertbe resolution

the smaller the dot pitch, the ________

Liquid Crystal Displays (LCD) Monitor

produces images by shining or reflecting light through a layer of liouid crystal and a series of color filters

Liquid crystal and hydrogenated

amorphous silicon(a-Si:H)

are contained between glass plates on the front of the monitor (LCD)

Light-emitting Diodes (LED)

provides backlight for the LCD monitor

Polarized filters

control the intensity and color of the transmitted light

Liquid crystal

is a material state between that of a liquid and a solid

nematic and smectic

2 phases of LCD:

red-green-blue filter

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

Twisted Nematic

these are the oldest,most common LCD screen type, and simplest of the three. In their default state, the crystals are twisted. When voltage is applied, they untwist to block light

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

advantages of twisted nematic

The viewing angle of the display

The ability to produce a wide range of colors

disadvantages of twisted nematic:

Vertical Alignment

These were designed to solve the contrast issues of TN LCD panels.When no voltage is applied, the liquid crystals sit vertically. When voltage is applied, crystals start to "tilt" 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:

Much more expensive than TN panel

disadvantages of vertical alignment:

In-Panel Switching

when voltage is applied, the crystals

rotate parallel ("in-plane") rather than upright to allow light to pass through

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

angular dependence of viewing

the primcipal disadvantage of an LCD is the _____

CRT displays

LCDs are superior to_____

Light Emitting

Curved face

Scanning electron beam

Veiling glare distortion

Spot pixel

Phosphor nonuniformity

Principal differences between CRT and LCD devices: CRT

Light Modulating

Flat Face

Individual pixel address

Pixel cross-talk distortion

Square pixel

LC nonuniformity

Principal differences between CRT and LCD devices: LCD

Resolution

Luminance

Contrast

Bit Depth

Uniformity

Glare

factors affecting image quality on monitor:

Resolution

It is based on how many pixels can be displayed in the horizontal and vertical dimensions

Resolution

The higher the number of pixels, the higher the ______

Luminance

it is a measure of 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

matrix size and bit depth

Uniformity

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

Glare

Monitors have design features to reduce this effect; however, it cannot be eliminated

Monitors should not be used in rooms with ambient or bright lighting