212 PRE FINALS

Computer Network

two or more objects sharing resources and information

computers, terminals, and servers that are interconnected by communication channels

·Local Area Network(LAN)

·Wide Area Network (WAN)

Ceographic Classifications:

Peer-to-Peer Network

Server-Based Network

Client-Based Network

Component Role Classification:

Local Area Network

It is a small area networked with a series of cables or wireless access points that allow computers to share information and devices on the same network

These are least expensive to install, much faster than WANs, and has the fastest

communication technology

Wide Area Network

It is a network that spans a large area

It is used to connect computers that are not physically attached but are connected thrpugh other means

Peer to Peer Network

Each computer on the network is considered equal

It is the most popular small office or home network configuration because it is the least expensive and most simple to setup

Server-Based Network

There is a centralized computer (server) that controls the operations, files, and sometimes the programs ofthe attached computers in the network

Client-Based Network

Similar to server-based network, however,the server processes as requested by the client and returns only the results back to the client

Server

Thin Client

Thick Client

There are three types of computers:

Server

lt manages resources for other computers,servers,and networked devices

Thin Client

It is a device that is found on a network that reouests services and resources from a server

Thick Client

It is a compputer that can work independently ofthe network and process and manage its own files.

Coaxial Cable

Fiber Optics Bundle

Twisted-Pair Wire

Wireless Connection

Communication Mediums:

Coaxial cable

It consists ofa center conducting wire surrounded byinsulation then a grounded shield of braided

wire.

It is the sturdiest wire used and is often found in the network infrastructure throughout a building

It is often connected to another type ofcommunication medium before it meets the device interface

Twisted-Pair Wire

It usually consists offour twistec pairs of copper wires that are insulated and bundled together

Category 5

The minimum recommended

standard of Twisted-Pair Wire is __________,and is the most commonly used connection medium in LANs

Fiber Optics Bundle

It uses olassthreads to transmit data on the network

It consists of a fiber optic core that is surrounded by a plastic protective covering

This type is much faster than its metal counterparts,but more expensive and much more fragile

Wireless Connection

The connection is made by using either infrared or radio freguencies as its means of communication

There is no physical cabling needed,but each device must contain the appropriate wireless transmitter/receiver

Network Interface Card (NIC)

It provides the physical connection between the computer and the network medium

It works with networking software to establish and manage the data, chop up data,and handle addressing issues

Network Hub

It is the simplest device that can be used to connect several pieces of equipment together for network communication purposes

It has several wiring ports available to receive and transmit data to various connected pieces of equipment

Network Switch

It is similar to a hub, but it sends data only to those devices which the data are directeed.

Network Bridge

It is sometimes created so that larger networks to reduce traffic within that network

Network Router

It can read portions of messages and direct

them to their intended target, even if the device is on a separate network and uses a different network protocol

It also helps with segmenting the network to allow access only for approved devices within that segment

Bus Network Topology

All devices are physically attached to and listen for communications on a single wire

This does not need any switches or hubs because computers broadcast and receive information down the single wire

Ring Network Topology

It is a network in which the devices are connected in a circle

The computers are connected in a circle, and a token is transmitted around the ring ("token ring")

Star Network Topology

It is a netowrk that has devices

connected to a central hub or

switch

This transmission of data may

be through another hub or

switch to an adjacent network

or directly to the device

It isthe most commonly used

network topology

Mesh Network Topology

It is a network that has multiple pathways

interconnecting devices andmnetworks

This has redundancy built in

with multiple connections

Digital Imaging and Communications in Medicine (DICOM)

It has become an almost universally accepted standard for exchanging medical images among networked medical devices

Health Level 7 (HL7)

It is an American National Standards Institute(ANSI)- accredited Standards Developing Organization International (SDO)

It oversees most clinical and administrative data and are generally used in communication between Hls and RIS

Hospital Information System (HIS)

holds the patient's full medicalinformation, from hospital billing to the inpatient ordering system

Radiology Information System (RIS)

holds all radiology-specific patient data, from patient scheduling information to the radiologist's dictated and transcribed report

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

Quality control

- Visible, on-going effort to collect information about an imaging operation

- Part of an overall Quality Assurance (QA) program

- Seeks to get the most efficient performance from both the imaging facility and the physician

1. Malfunctions

2. Unpredictability

3. Inefficient use of radiation

4. High fluoroscopic outputs

5. Radiation not reaching receptor

6. Inadequate filtration

7. Oversized collimation

QC can detect:

1. Acceptance Testing

2. Establishment of baseline performance

3. Diagnosis of changes in performance

4. Verification of correction of deterioration

Components of QC:

Diagnostic quality

● Quality image that makes accurate diagnosis possible

● Can be described in terms of contrast, resolution, and noise

image and accurate report of findings.

The end product in radiography is the ...

● Calibration of the generator

● Collimation

● Beam alignment

● Linearity of exposure

● Spatial resolution (focal spot)

Computed radiography still uses conventional radiographic equipment so basic radiography quality control

testing is still needed:

Process map

Flowchart of the steps involved in performing a DR exam

Reject Analysis

• a time-honored method for assessing and improving quality of imaging operations

1. Collection of data

2. Data must be analyzed to reveal recurring causes

3. Results need to be reported to management/staff

4. Action needs to be taken based on the results to affect any improvement.

Reject analysis:

- to maintain optimal quality of diagnostic images;

- to reduce unnecessary radiation exposure to patient and staff;

- to be cost effective

Objectives of QA program:

1. Quality Control tests

2. Administrative procedures

3. Preventive maintenance procedures

4. Training

The QA program has many facets, including:

Quality control

• An integral part of quality assurance

• Involves specific actions designed to keep measurable aspects of the process involved in manufacturing a

product (image) or providing a service within specified limits.

- The inherent variability of the process or equipment

- The age, reliability, and frequency of use of the equipment

- The criticality of the element in the imaging chain

The frequency of any QC test depends on the following variables:

Administrative procedure

These procedures are designed to verify that QC testing is effective

Preventive maintenance procedure

These are performed on a regularly scheduled basis with the goal of preventing breakdowns due to equipment failing

without warning signs detectable by monitoring.

Quality Assurance Committee

Personnel in the QA program who are responsible to oversight of the QA program, setting the goals and

direction, determining policies, and assessing the effectiveness of QA activities

Quality Assurance Committee

They have an overall documented strategy with clearly defined work plans to achieve the goals and

objectives of the radiology department.

- Medical Physicist

- Radiologist

- Biomedical engineer

- Medical Imaging Technologist (MIT) and Radiographer

- Information Technology (IT) Technician

QA committee members includes:

Medical physicist

An individual who is competent to independently practice in one or more of the subfields in medical physics.

Radiologist

A medical doctor who specializes in the diagnosis and treatment of disease and injury by using medical

imaging technologies.

Biomedical engineer

use their knowledge of modern biological principles in their engineering principle to

design and develop devices and procedures that solve medical and health-related problems.

- Corrective and preventative maintenance

- Fault Reporting

Biomedical engineer are involve in;

Medical imaging technologist (MIT) & Radiographer

- Ensuring that the appropriate protocol and technique factors are used for the requested examination.

- Ensuring that the QC tests are performed, interpreted and recorded appropriately.

- Perform all the checks for the daily, monthly and quarterly QC testing of equipment

- Report faults immediately any deviation in trend of equipment performance to QA manager

- Undertaking additional continuous education courses

Information Technology (IT) Technician

• A key element of any digital radiology facility that intends to store, review and distribute images

electronically or using hard copy. Their responsibility includes;

• Maintenance of the integrity of system databases to ensure continuous and accurate operation of the

information systems.