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THE PROCESS OF CARE AND THE ROLE OF 5. Contrast material/metal: bright white.
IMAGING FILM-SCREEN RADIOGRAPHY
➢ Film –Screen Radiography has been
the workhorse of radiology ever since
the discovery of x-ray by W.C.
Roentgen in 1895.
➢ Today film –screen radiography has
➢ what is wrong, which entails identifying entered into the domain of digital
the problem and establishing a imaging, or filmless imaging as it is
differential diagnosis. sometimes referred to.
➢ how serious is it, which involves testing ➢ It is the goal of radiology departments
the differential diagnosis and to eliminate film –based imaging
determining the extent of the problem. systems and introduce new
➢ what to do, which based on analysis of technologies for the purpose of
test results,concludes with a treatment improving diagnostic interpretation
decision. and digital image management and
to reduce the radiation dose to
The process of providing an accurate, patients.
expedient medical diagnosis via imaging ➢ These technologies include not only
can fail for several reasons such as: digital image acquisition modalities
➢ Wrong study requested but also digital image processing and
- Improper technique display, storage, and image
➢ Poor study acquisition communication or image transmission.
- Poor instrumentation/calibration ➢ Digital image acquisition modalities
- Insufficient background include: Computed Radiography (CR),
➢ Poor study interpretation Digital Radiography (DR), Digital
- Poor data presentation mammography, digital fluoroscopy for
- Poor reading skills routine gastrointestinal fluoroscopy
➢ Poor study documentation/ and vascular imaging, computed
communication tomography (CT), Magnetic
resonance Imaging (MRI), Nuclear
Five principal densities are recognized on medicine , and Diagnostics medical
plain radiographs in order of increasing sonography.
density: DIGITAL RADIOGRAPHY
1. Air/gas: black, e.g. lungs, bowel and ➢ Digital Radiography - refers to
stomach projection radiography by: euclid
2. Fat: dark grey, e.g. subcutaneous seeram, whereby computers process
tissue layer,retroperitoneal fat data collected from patients using
3. Soft tissues/water: light grey, e.g. solid special electronic detectors that have
organs,heart, blood vessels, muscle replaced the x-ray film cassette.
and fluid-filled organs such as bladder - Digital radiography has also been
4. Bone: off-white referred to as filmless radiography.
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- The film image appears with

varying degrees of blackening as a
result of the amount of exposure
transmitted by different parts of the
anatomy.

- The Detectors measure and

convert x-ray attenuation data
from the patient into electronic
(analog) signals that are
subsequently converted into digital - More exposure produces more
data for processing by a blackening and less exposure
computer. produces less blackening.
- The result of this processing is a - The blackening is referred to as the
digital image that must be film density and the difference in
converted so that it can be densities in the image is referred to
viewed on a computer monitor. as the film contrast.
- The displayed image can be - The film, therefore , converts the
manipulated using a variety of radiation transmitted by the various
digital image processing types of tissues ( tissue contrast)
techniques to enhance the into film
interpretation of diagnostic ➢ LIMITATIONS OF FILM –SCREEN
radiology images. RADIOGRAPHY
- Digital radiography also includes - One of the major problems with
image and information the radiographic imaging process
management systems, image is poor image quality if the initial
storage, and image data radiation exposure has not been
communication. accurately determined .
➢ BASICS STEPS IN THE PRODUCTION OF A - For example: if the radiation
RADIOGRAPH exposure is too high, the film is
➢ The production of a film –based overexposed and the processed
radiographic image involves image appears too dark and the
several steps: radiologist cannot make a
diagnosis from such an image.
- If the radiation exposure is too low,
the processed image appears too
light and not useful to the
radiologist
- If the images lack of proper image
density and contrast, and would
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have to be repeated to provide an - Better image quality

acceptable image quality needed - Rapid image acquisition, and
to make diagnosis - Image access at remote
locations

➢ SCREEN FILM IMAGING SYSTEM VS

DIGITAL IMAGING SYSTEM:
- The transition from an SF
environment to a new digital
environment should be considered
as a complex process.
- Technical factors concerning
image acquisition, management
of patient dose, and diagnostic
image quality are some issues that
could influence this process.
- In a transition process from SF to
digital, patient radiation doses
could increase 40–103% .
- When compared to SF, digital
technology could increase patient
radiation doses due to the wide
dynamic range they have.
- However, the dynamic range is - Windowing can be used to
useful because it contributes to a manipulate the image brightness
better clinical image quality when and contrast to suit the needs of
compared to traditional SF systems. the observer.
- The processes of X-ray detection
and readout digital detectors of
digital systems offer several
advantages when compared to SF
systems.
These include:
- Wide dynamic range
- Adjustable image processing
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magnified view of a selected part

of the image.

➢ A DIGITAL RADIOGRAPHIC IMAGING

SYSTEM
➢ Major technical components :
data acquisition, computer data
processing , image display & post
processing.

➢ Digital radiography images may be

reviewed and reported on a computer
workstation in higher image quality for
accurate diagnosis. ➢ DATA ACQUISITION – Refers to the
- Magnification of areas of interest collection of x-rays transmitted through
- Alteration of density the patient. It is the first step in the
- Measurements of distances and production of images.
angles. ➢ In digital radiography , special
electronic (digital ) detectors are used
to replace the x-ray film cassette that
is used in film –based radiography.
➢ These digital detectors are of several
types and utilize various technologies
to convert x-ray to electrical signals .
➢ This light is collected by photodiodes

- This allows various manipulations of and converted into electric charge

images as well as application of while an analog-to-digital device

functions such as measurements of converts it into a corresponding digital

length and angle measurements. image. Figure shows the SPS scanning

- Shows a ‘magnifying glass’ process.

function, which provides a

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is, 0 or 1). These digits are referred

to as binary digits, or bits. Bits are
not continuous rather they are
discrete units.
- Computers operate by processing
and transforming these discrete
units (binary numbers) into other
discrete units (Decimal numbers).

Example: it would first have to be converted

into digital data (binary representation ). Which
Example: One type of detector will first convert would appear as 01000101 01010101
x-ray into light, followed immediately by the 01000011 010001010101010101000011
conversion of the light into electrical signals.
➢ Another type of digital detector will
➢ IMAGE DISPLAY AND POST
avoid the light electricity conversion
PROCESSING:
process and convert x-ray directly into
- The output of computer
electrical signals.
processing, that is, the digital
➢ The analog signals then be converted
image, must first be converted into
into digital data for processing by a
an analog signal before it can be
computer. The conversion of analog
displayed on a monitor for viewing
signals into digital data is the function
by the observer. Such conversion is
of the analog –to-digital converter
the function of the digital –to-
(ADC).
analog converter (DAC) .
- The image displayed for initial
➢ COMPUTER DATA PROCESSING:
viewing can be processed using a
- The ADC sends digital data for
set of operations and techniques
processing by a computer. The
referred to as post- processing
computer uses special software to
techniques, to transform the input
create or build up digital images
image into an output image that
using a binary numbers system.
suits the needs of the
- While humans use the decimal
observed”radiologist” in order to
number system. That operates with
enhance diagnosis.
base 10, that is, 10 different
Example : Operation can be used
numbers (0,1,2,3,4,5,6,7,8,9).
to reduce the image noise,
- Computers use the binary number
enhance image sharpness.
system . Operates with base 2, that
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- To simply change the image computer communication

contrast, or to stitch several images networks to transmit images from
together to form one image . The acquisition phase to the display/
effect of one common and viewing and storage phase.
popular digital image processing - If the image transmission is within a
tool, referred to as gray-scale hospital (intranet) , local area
mapping. networks (LANs) are used.
- If images have to be sent outside
the hospital to remote locations
(internet) , networks such as wide
area networks (WANs) must be
used.
➢ PICTURE ARCHIVING AND
COMMUNICATION SYSTEM (PACS):
➢ PACS - are being used for
storing/archiving and
communicating images in the
- Digital image – processing tool of
digital radiology department.
gray –scale mapping can change
- In addition , information systems
the picture quality to suit the needs
such as Radiology information
of the viewer.
system (RIS), Hospital information
➢ IMAGE STORAGE :
systems are now being integrated
- The vast amount of images
with the PACS via computer
generated for the wide range of
networks.
digital radiology examinations must
- Using communication standards
be stored not only for retrospective
such DICOM (Digital Imaging
analysis but also for medico- legal
communications in Medicine) and
purposes.
HL-7 (Health Level -7) for effective
- Various kinds of storage devices
management of patient
and systems are used for this
information
purpose. Example : magnetic types
➢ An important element of image and
,disk, and laser optical disks for long
data communication is image
term storage.
compression to reduce storage space
- Image storage : In PACS
and decreased image transmission
environment . Example: such as
time.
RAID (redundant array
➢ Two popular compression method for
independent disk. Images stored in
used in digital radiology are Lossless or
a short term archival system are
reversible and Lossy or irreversible .
deleted after a period of time
defined by the institution.
➢ IMAGE AND DATA COMMUNICATIONS:
- Image and data communications
are concerned with the use of
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➢ IMAGE AND INFORMATION ➢ PACS: MAJOR COMPONENTS AND

MANAGEMENT CORE TECHNOLOGIES:
- Refers to the use of PACS and
information system such as RIS and
HIS to manage the vast number of
images and text data produced in
a digital radiology department
with databases and file
management software.
- While the RIS and HIS handle
essentially textual information ,
➢ The major components of pacs and
specially dealing with business
their functional relationship these
operations for the entire hospital.
includes:
- PACS handle images generated
- Digital image acquisition modalities
by the various digital imaging
- Database/image server
modalities.
- Web server
➢ What is PACS exactly ?
- Archive server
- Some individuals believe that
- Short term and long term archive
perhaps it should be called IMACS
server
( Image Management and
- Image display subsystem
Communication Systems) ;
➢ All are connected via computer
However, the more popular
networks, using gateways and
acronym is PACS.
switches. In order to extend their
- Mosby Medical Dictionary (2009)
functionality and usefulness.
defines PACS as “a network of
➢ PACS are integrated with RIS-HIS
computers used by radiology
through computer communication
departments that replaces film with
networks via RIS-PACS broker and Tele
electronically stored and display
-PACS (satellite connection to remote
digital images.
facilities)
➢ PACS is a digital radiology computer-
➢ COMMUNICATION AND INTEGRATION
based system or medical device
OF ALL COMPONENTS REQUIRED
where images acquired from patient
COMMUNICATION PROTOCOL
are:
STANDARDS:
1. Displayed on monitors for viewing
➢ Two data standards in a PACS
and subsequent digital image
environment:
post- processing.
- DICOM Standard that essentially
2. Stored and archived in electronic
addresses the communication of
form
images (image data)
3. Transmitted to other locations via
- HL-7 – A communication standard
computer communication
configured for information systems,
networks.
which addresses the
communication of textual data,
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such as demographics, admission, - Star Network configuration, where

& discharge transfer, and the type all computers are connected to a
of imaging examination and central or host computer called a
radiology reports. Hub.
➢ COMPUTER NETWORKS - Ring Network configuration, a
- The hardware components of computer is connected to two
PACS and the associated adjacent computers and all
information system (RIS-HIS) are all computer connections form a ring.
connected. - In general, computers are
- These connections are made connected by wires (co-axial
possible via Computer Networks. cables, optical fiber cables) or
- Networks allow information to be wireless connections (radiowave,
transferred and shared among microwave and satellite links)
computers and consist of both capable of transferring data in
hardware components and the different rates.
necessary software to enable the - This data transfer rate of the
hardware to function. network is called the Bandwidth.
- LOCAL AREA NETWORK (LAN)- The bandwidth will vary depending
Connects computers that are on the physical connection
separated by short distances such between computers.
as within a radiology department, - The unit of bandwidth is megabits
a building or two or more buildings. per second ( 1Mbps = 106 bps)
- WIDE AREA NETWORK (WAN) – - Several computer network
Connects computers that are technologies, their bandwidth, and
separated by large distances, such associated times for transferring
as in another state or country. The digital images.
internet is a perfect example of
WAN
➢ The network topologies for LANs: Bus
Network, Star Network, and Ring
Network.

➢ COMPUTER NETWORKS
- Information sent through the
network is divided into packets of
fixed or variable size sent via
switching devices to the
appropriate computer on the
network
- In the Bus Network configuration,
- An individual device is referred to
computers (nodes) connected via
as a node, and the connections
a single cable
among nodes are called links.
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- Other hardware components such (RAID) redundant array of

as bridges and routers play an independent disks.
important role in sending the - It contains several magnetic or
packets and ensuring that they get optical disks that can perform as a
to the correct computer large disk drive. The result is an
destination. automated library system (ALS),or
➢ Communication protocol: a “Juke box”.
- such protocol in a PACS - RAID are used primarily for short
environment is the TRANSMISSION –term storage.
CONTROL PROTOCOL/ INTERNET - Digital linear tape (DLT) – usually 0.5
PROTOCOL (TCP/IP) –inch magnetic type that is
- TCP divides the information to be intended for long-term storage of
transferred into packets. images. These image storage
- IP provides bandwidth web components can be connected
services for the information data by a sub-network called storage
and imaging data transfer time to area network (SAN).
the destination. - Storage area network (SAN)– a
➢ PACS MAIN COMPUTERS: fiber optic high- speed network (up
- Images and data acquired from to about 100 megabits/ sec)
patients are sent via computer sometimes referred to as a fiber
networks to the PACS main channel.
computer. Which is the heart of the
system and consists of high end
computers or servers.
- This computer is sometimes referred
to as the PACS controller, the
database server or the image
server.
- Images and patient data are sent
from the acquisition gateway ➢ A dedicated image storage network
computer. The HIS and the RIS to called a storage area network (SAN)
the PACS controller. Which has a for connecting storage devices in
database server as well as an PACs.
archive system. ➢ IMAGE COMPRESSION:
➢ PACS IMAGE STORAGE - The purpose of compression is to
- Storage technologies for PACS speed up transmission of
include solid-state memory information (textual data and
magnetic data carriers (disk & images) and to reduce storage
Types), and optical disk. requirements.
- One of the popular storage Several image compression
technologies used in PACs is the methods are :
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- Lossless compression or reversible

compression where no information
is lost in the process
- Lossy compression or irreversible
compression, where some
information is lost in the process.

➢ The RIS /PACS BROKER

- The PACs are concerned primarily
with image data, and the RIS deals
with textual data such as patient
demographics.
- In order for the PACs and the RIS to
➢ Joint photographic experts group
communicate with each other, A
(JPEG)
device is needed to act as a
- Image compression features both
translator so that the
lossy and lossless compression
communication can be effective
methods. For medical images,
and accurate.
JPEG is DICOM’S present method.
- Such a device is referred to as the
- JPEG 2000 uses wavelets (wavelet
“BROKER” more specifically the
compression) in an effort to
RIS-PACs broker.
decrease the image size and
➢ Types of RIS-HIS integration one that
enhance image quality.
uses broker technology and the other
➢ Display and Analysis Workstations:
one that is brokerless technology.
- The workstation is an essential
component of PACs, since it
provides a system –to-user
interface.
- The ultimate goal of PACs
workstation is to provide the
radiologist , in particular, with a tool
to make a diagnosis and the
technologist to assess the overall
➢ SYSTEM INTEGRATION:
image quality before the image is
- The RIS/HIS/PACs must be able to
sent to the PACs server.
exchange data and information is
such a way that it is seamless to
technologist, radiologist and other
related personnel in the hospital.
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- Integration means to “combine “. - PACS are directly related to

To perform this task requires a DICOM: they are the standard
connection, an interface to incarnate. Their functionality is
facilitate communication in order DICOM-driven, which guarantees
to make up the whole. their interoperability.
- Interface is a computer program ➢ DICOM Conformance Statement:
that sets up the rules for - Defines services including
communication so that different modalities specific storage
systems (RIS-HIS-PACs) can - Defines other specific
exchange data. conformance issues
➢ INTEGRATION OR COMMUNICATION - Transfer syntax (encoding)
STANDARDS FOR PACS: - Limitation
- In order to integrate the two - Configuration
information system the RIS-HIS . Two - Physical network
communication standard the HL-7 - Required standard format
and the DICOM - Public document shared on
- HL-7 deals with the flow of textual website.
information between the HIS and ➢ A Patient IOD, for example, can be
the RIS and other information described by patient name, ID, sex,
system such as NIS (nursing age, weight, smoking status, and so on
information system). – as many attributes as needed to
➢ DICOM – deals primarily with the capture all clinically relevant patient
exchange of images in the radiology information.
department and facilitate
communication among specific
imaging equipment.
- How Does DICOM Work?
- DICOM uses its own lingo, based
on its model of the real world
(DICOM information model).
- All real-world data – patients,
- DICOM maintains a list of all
studies, medical devices, and so
standard attributes(more than
on – are viewed by DICOM as
2,000 of them), known as the
objects with respective properties
DICOM Data Dictionary, to ensure
or attributes.
consistency in attribute naming,
- The definitions of these objects and
formatting, and processing.
attributes are standardized
- DICOM represents this processing
according to DICOM Information
with a service rendering model:
Object Definitions (IODs). Think
Application Entities provide
about IODs as collections of
services to each other because
attributes, describing IOD
each service usually involves some
properties.
data exchange. Typically
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performed over a computer

network.

- It becomes natural to associate

particular service types with the
data (IODs) that they process.
- DICOM calls these associations
Service-Object Pairs (SOPs), and
groups them into SOP Classes.

- The statement explains which SOPs

(services) the unit supports, and to
what extent (SCU, SCP, or both) it
supports them.
- DICOM Conformance Statement is
your most essential planning guide
for any DICOM-related project.