CT

Seeram Chapter 2:

Introduction to

Computers

Electronic Computer Technology

Vacuum tubes

Discrete Semiconductors

Integrated Circuits

Early Computers1951-1958Vacuum tube memoryInput / Output

Punch cardsMagnetic Tape

Electronic Computer Technology

Warm-upRan hothot

tube filaments required constant heating

computers required air conditioning

Frequent failures

Computers after Vacuum Tubes1959-1963Transistor & magnetic

core memorySmallerLess power needed

Discrete Semiconductor Components in Computers

transistorsmagnetic memory coresSpace requirements

largebut

smaller than vacuum tubesRan much coolercooler than vacuum tubes

Computers: The Big JumpIntegrated Circuits

millions of semiconductor components in tiny packagelower production costs

Extremely smallExtremely fastRun very coolVery reliable

Categories of Computers

Super computers

MainframesMinicomputersMicrocomputers

5th Generation: Supercomputers

Large (even today)ExpensiveFound only in major research sitesApplications

weatherscientific modelingoil explorationother research

Mainframe ComputersLarge$$$Requires teams of expertsLarge # of usersApplications

large corporationsgovernmenthospitals

Microcomputer

“PC”Rapidly changing

technologyLow costNon-proprietaryFirst common in

1980’s

MinicomputersFirst seen in 1970’sMuch less expensive than mainframesMedium-sizedProprietary ($$$)

partsoperating systems

Computer used for CTAppropriate

Size price

Applications imaging, reconstruction archiving

Basics

Input Processing Output

InputManual

keyboardmouse

ElectronicCT detectorsCR Plates

Input Processing Output

Other Voice

recognition

Analog to Digital Conversion(A to D)

Analog(continuously varying)

Digital(discretely varying)

Analog to Digital Conversion(A to D)

Many real world inputs are analog voltagesCT detector intensity

Analog values must be converted to a # to use in a computer

0.2

0.4

0.6

0.8

Input analog voltage

1 2 3 4Digital conversion

to computer

ProcessingCentral Processing Unit (CPU)

ArithmeticLogic

Internal MemoryScratchpad

Input Processing Output

OutputHard copy

printerSoft copy

CRT

Input Processing Output

Storage• disk• tape

Hardcopy DevicesDo not lose information

when power is shut offPrinters

impact (dot matrix) noisy multi-copy

non-impact (quiet) ink jet laser

PlottersMicrofilm

Softcopy DevicesLose all information

when power shut offFlat-panel monitors

Digital to Analog Conversion(D to A)

Computer reconstructs digital imageset of numbers

Computer displays analog image

125 25 311 111 182 222 176

199 192 85 69 133 149 112

77 103 118 139 154 125 120

145 301 256 223 287 256 225

178 322 325 299 353 333 300

Computer System Elements

Hardware Software

People

Hardware

ComputerPeripherals

keyboardprinter

Hardware Software

People

HardwareExamples

Disk DriveMemory

Random Access (RAM)

Read only (ROM)

MouseKeyboardCables

Hardware Software

People

SoftwareInstructions to computer

Operating SystemApplications

Hardware Software

People

Operating System

Fundamental instructions to hardwareWhat to do when computer first turned onHow to interact with hardware

CRTKeyboardMouseModem

Hardware Software

People

Operating SystemComputer “face” presented to users

WindowsDOSMAC OS

Dictates how usersinteract withcomputer torun applicationsoftware

Hardware Software

People

Application SoftwareComputer instructions which perform

some desired taskBalance checkbookPlay a gameCalculate (reconstruct)

a CT image

Hardware Software

People

Application SoftwareUsually a quasi-quasi-

EnglishEnglish languageBasicFortranCOBOLC

Languages provide tools to software developers to efficiently design application software

Forms![FDoSurvey]![FExpsSub].Form![KVEff] = Val(Mid$(MyData, 2, 10))Forms![FDoSurvey]![FExpsSub].Form![KVAVG] = Val(Mid$(MyData, 12, 10))Forms![FDoSurvey]![FExpsSub].Form![MRMEAS] = Val(Mid$(MyData, 22, 10))Forms![FDoSurvey]![FExpsSub].Form![TIMEMEAS] = Val(Mid$(MyData, 32, 10))DumText = Mid$(MyData, 42, 3)'MsgBox$ (DumText)If Right$(DumText, 1) = "+" Then DumText = Left$(DumText, 2)Else DumText = Left$(DumText, 1)End If'MsgBox (DumText)MyData = Right$(MyData, Len(MyData) - Len(DumText) - 41)'MsgBox (MyData)NKvs = Val(DumText)'MsgBox (NKvs)KVMAX = 0If NKvs > 0 Then For DumNum = 1 To NKvs 'MsgBox (Val(Mid$(MyData, 10 * (DumNum - 1) + 1, 10))) If (Val(Mid$(MyData, 10 * (DumNum - 1) + 1, 10))) > KVMAX Then KVMAX = (Val(Mid$(MyData, 10 * (DumNum - 1) + 1, 10))) End If NextForms![FDoSurvey]![FExpsSub].Form![KVMAX] = KVMAXEnd IfDoCmd.Close acForm, "FNeroExp"End Sub

PeopleDesigners

hardwaresoftware

Usersrun applicationsprovide inputuse output

Meaningless Slide

Storage HardwareRandom vs. Sequential

Direct (random) accessany data can be accessed at any timedisks

Sequential accessdata only accessed in serial fashionmust pass through unwanted data to reach

target datatapes

information encoded magnetically

Data Storage Technologies(constantly changing)

DisksFormats

Hard removable non-removable

Floppy CD

CD-RW CD-R

Tapelots of dataserial access

Technologies» Magnetic (disks & tape)

re-writable

» optical (disks & CD’s) re-writable write once

Data Communication

Featuresspeedcosttopology

wiring scheme

Data transmission between computers

Data Communication Technologies

Telephone linestwisted pair wires

Coaxial cableFiber optic cableMicrowavesSatellitesRadio waves

NetworksLAN (Local area network)

computers connected in one areaLAN’s can be connected together

WAN (Wide area network)computers connected together over large

distancesCommunications protocols

Ethernet uses bus technology

Internet

File ServerSpecial computer which handles functions

for connected computersdisk accessprinting

Incorporates securitymay limit user to selected files or directoriesmay limit # of connections per usermay limit times when network available

Typical Lan

NetworkGateway

OtherNetworks

Radiology Computer Systems

RIS

Professional

Billing

CR

CTMRI

Digital Dictation

Mammography

Digital Spot Film

Voice to TextDictation

WebServer

InsuranceCarrierHospital

Admission/Discharge

Billing

Reports

PACS

Angio / Digital

Subtraction

The Computerization of Radiology

RIS PACS

CT CR MRIDigitalFluoro

DigitalAngio

Dictation Admin

RadiologistWorkstation

RadiologistWorkstation

RadiologistWorkstation

3DWorkstation

NucMed

LaserPrinter

Web Browser

The Internet

Network connecting all computersOriginally developed for security

Single bomb can’t destroy all U.S. computing facilities

Can connect large number of computers in many locations

Communicates in finite “packets”Each packet has specific destination (address)Packets can be

E-mail Web site

Allows linkinglinking of information