Transcript Computerized & Digital Radiography

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Historical perspectives of computerized
imaging
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Computer classifications
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Components of computer hardware
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Define computer terminology
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Are often classified according to size,
processing speed, and storage capacity.
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Supercomputers – are the fastest and
highest-capacity computers, containing
hundreds to thousands of microprocessors
(eg: weather forecasting)
Mainframe computer – are fast, mid-to-large
–size, large-capacity system that has multiple
microprocessors. They can support a few
hundred to thousands of users (eg: ATM’s)
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Workstation – powerful desktop system
usually connecting individual users to a larger
computer system to share and transfer
information
Microcomputers – best known as PC’s or palm
pilot.
1946 - First all electronic, general
purpose digital computer
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Basic form = input, output, and processing
devices
Input devices: keyboards, mice, microphones,
barcode readers, touch screens, and image
scanners.
Output devices: monitors, printers, and
speakers
Processing: central processing unit (CPU)
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Computers operate on the Binary Number
System
It has only two digits, 0 and 1
Computers function by converting all data
into binary values.
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Represents one character, digit, or value.
A bit describes the smallest unit of measure 0
or 1 – computers ultimately understand only
0 or 1
Byte are 8 bits
Alphabet in
Binary
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Analog refers to a continuously varying
quantity
A digital system uses only two values that
vary discretely through coding. Binary
Number System
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Analog - one value
blends into another
(like a
thermometer)
100
80
60
East
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Digital - distinct
separation
98.6
exact
40
W est
20
N orth
0
1st
3rd
Q tr
Q tr
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Computer processing is performed by a
series of transistors.
Transistors are either on or off.
◦ If the transistor circuit is closed and current passes
through, it is assigned a value of 1.
◦ If no current passes because of the circuit being
open, then 0.
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Transistors can be switched on and off
millions of times in a second. Each 1 or 0 is a
bit.
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One byte is the amount of memory needed to
store one letter.
A kilobyte represents 1024 bytes, megabyte
is 1 million bytes, gigabyte is approximately
1 billion bytes
Memory is talked about in kilo, mega, giga, or
tera.
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Hardware – the nuts & bolts of the computer
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Software – computer programs
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Hardware: Motherboard – the largest circuitry
board inside the computer and it contains
many important small components.
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Central processing unit, or microprocessor is
the brain of the computer.
It is a small chip found on the motherboard.
(not the “box” as most people refer)
CPU = a series of transistors that manipulate
data received from the software.
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Basic tasks are to read data from storage,
manipulate the data, and then move the data
back to storage or send it to external devices,
such as monitors or printers.
CPU’s are named after its manufacturer and
the speed at which it manipulates data.
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The basic input/output system.
A simple set of instructions to bring the
computer to life and run diagnostic test to
make sure the peripherals are functioning.
ROM = Read-only memory. Contains
information supplied by the manufacturer,
cannot be written on or erased. (how to start
the system)
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After start up, BIOS oversees the basic
functions of receiving and interpreting signals
from the keyboard and other ports.
BIOS is the intermediary between the
operating system (OS) and the hardware.
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The bus provides the connections for the
information to flow within the computer.
There are several: ex. connecting the
microprocessor and the system memory
(graphics port, video adapters, universal
serial bus)
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RAM = Random access memory.
◦ Data can be stored or accessed at random from
anywhere in the main memory.
◦ Only temporary storage when the computer is
turned off RAM is wiped clean.
◦ Usually expressed as MB (mega), GB (giga) or TB
(tera)
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CMOS = (complementary metal oxide
semiconductor) retains information about the
hardware while the computer is turned off.
Ex: date and time
Connectors sticking
out of the
back of the PC
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Parallel (printer port) = 8 bits of data through
the connection.
Serial (mouse) = 1 bit of data down a single
wire.
USB (universal serial bus) = multiple devices
may be connected into one port.
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Sound Card
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Network Card
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Provides electricity and contains a fan to keep
the computer cool.
Contains a transformer that converts AC from
the wall to DC.
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The main storage for programs and
documents.
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DVD’s can hold up to 7 times more than the
CD.
3 types of CD/DVD:
◦ ROM (read-only memory)
◦ R (write once-read many)
◦ RW (read and write many times)
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Starting in the center and spiraling out.
Tiny depression (pit) is laser burned into the
disk to create a series on pits and areas not
burned.
To read, a laser scans the disk if the laser hit
a pit the light reflects back. A diode
translates the impulses into binary.
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Common type of secondary storage are
optical disks, tape, diskette, Magnetic tape,
CD or DVD
 Keyboard
 Speakers
 Mouse
 Microphones
 Scanners
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The OS takes over just after the computer
wakes up and allows the computer to begin
doing tasks.
Ex: Windows by Microsoft, Macintosh OS,
UNIX/Linux
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Early OS’s were command based. To save a
file the user needed to know the word
commands.
Now most computers use GUI, graphical user
interface.
◦ A picture (icon) based program, where the mouse is
used to point and click on the function.
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Is the most commonly used. Some PACS
systems used a proprietary system.
UNIX is usually used on large servers because
of the exceptional multitasking capabilities.
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Soft copy = CRT or LCD display
(Plasma screen)
Hardcopy = film
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Digital images are made of discrete picture
elements, arranged in a matrix. The size of
the image is described in the binary number
system
Modern imaging systems are at least 1024 x
1024
4096 x 4096 is being developed for digital
radiography. The number of pixels on a
display determines the resolution.
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PACS - Picture Archiving & Communications
System
DICOM - Digital Images & Communication
in Medicine
TELERADIOGRAPHY -Remote Transmission of
Images