Wilhelm Roentgen discovered X-rays in 1895 while experimenting with cathode ray tubes. He observed that a screen coated with barium salt would fluoresce when placed near the tube, even though the tube was covered. This led him to conclude that a new type of penetrating radiation was being emitted. The first medical X-ray image ever taken was of Roentgen's wife's hand. X-rays are a type of electromagnetic radiation that is able to pass through and penetrate materials like human tissue. They are used widely in medical imaging procedures. Digital radiography systems like computed radiography and digital radiography have largely replaced traditional film-based X-ray systems, allowing for the digital capture, processing,

1. Eng: Mohamed Gad

3. NGOJO 3
X-rays were discovered in 1895
when Wilhelm Conrad Roentgen
observed that a screen coated with a barium
salt fluoresced when placed near a cathode
ray tube. Roentgen concluded that a form of
penetrating radiation was being emitted by
the cathode ray tube and called the
unknown rays, X-rays.

4. NGOJO 4
First X-ray Image

5. • X rays are the ionizing electromagnetic radiation emitted
from a highly evacuated high-voltage tube. Inner orbital
electrons in the target anode are stimulated to emit x-
radiation via bombardment by a stream of electrons from
a heated cathode.
• X-rays, like gamma rays, are penetrating and carry
enough energy to ionize atoms in their path. Nearly
identical to gamma rays, x-rays require shielding to
reduce their intensity and minimize the danger of tissue
damage to personnel. Mishaps with x-rays can cause
severe radiation burns and deep tissue damage and can
lead to various cancers.
NGOJO 5

6. Radiation is energy in the form of waves or particles.
Radiation which is high enough in energy to cause ionization is called
ionizing radiation. It includes particles and rays given off by radioactive
material and high-voltage equipment. Ionizing radiation includes x-rays,
gamma-rays, beta particles, alpha particles, and neutrons.
Without the use of monitoring equipment, humans are not able to
"find" ionizing radiation. In contrast to heat, light, odors and noise,
humans are not able to see, feel, taste, smell, or hear ionizing radiation.
NGOJO 6

7. Units of Radiation Exposure and Dose
• Exposure (Roentgens)
• Dose Equivalence (Sievert)
Relative biological effectiveness of
different types of ionising radiation
• The Effective Dose Rate (Sievert)
• Absorbed dose (Gray)
NGOJO 7

8. Dose
International Commission on Radiological Protection (ICRP)
Prescribed Limits per annum
• Members of public
• Radiation workers
20 mSv per annum above background
150 mSv to eye
500 mSv to hands
1 mSv per annum above background
5 mSv to eye
20 mSv to hands
•Pregnant women must receive no more than 2mSv
per annum
NGOJO 8

9. Eng: Mohamed Gad

10. There are two ways to obtain Digital X-rays:
• Computed Radiography
• Digital Radiography

11. • A Digital way of doing general radiography
with Conventional X-ray machines

12. • Computed Radiography (CR) is a process of
capturing radiographic data from a conventional X-
ray machine and processing the data digitally to
produce crisp and high quality radiographic images

13. • For exposure, an Imaging Plate (IP) is placed in
a cassette instead of a piece of film. The IP
captures and "stores" the X-rays
• The image is "developed" in a CR reader instead
of a film processor. The CR reader extracts the
information stored in the plate and produces a
digital image

14. • Computed Radiography is a digital image
acquisition process that produces images
that have much better contrast than a
Conventional X-ray film-screen system

15. Basic Modules of CR
MATRIXLR 3300
Digitizer
Preview & ID Station
Processing Server
ID Tablet
Laser Camera
Cassette with
Imaging Plate

16. • The Imaging Plate looks like the intensifying
screens found in Conventional film-screen
cassettes
• They are made of photostimulable phosphor

17. • Instead of emitting light immediately when
exposed to X-rays, the photostimulable phosphor
has the special property of storing the X-ray energy
in a latent form and releasing the same when
stimulated by a laser energy in the CR Reader /
Digitizer

18. • Storage phosphors are unique because they respond to
a very wide range of X-ray exposures
• This latitude gives the flexibility in selecting X-ray
technique and takes care of under or over exposure
• Regardless of the exposure, the image can be
displayed correctly
• As a consequence, retakes due to inappropriate
exposures are drastically reduced

19. laser stimulation
EmissionAbsorption
x-rays
electron
trap
electron
trap

20. • The imaging plate is coated with photostimulable
phosphor, also called storage phosphor
• The phosphor material is generally a kind of
Bariumfluorohalide
• The Imaging Plate contains not only the phosphor
layer, but also a protective coat, a conductive layer,
support and laminate layers

21. • Incident X-rays excite electrons into a higher energy
level (electron traps)
• A latent image is created in the form of “stored
energy”
• Stimulation with a scanning laser beam releases
electrons
• Typical wavelength of the stimulating laser is 633 nm
• Falling back, electrons emit luminescent light
• Typical wavelength of the emitted light is 390 nm

23. • The emitted light intensity is proportional to the
original incident X-ray intensity
• The emitted light is captured with an optical array
and a photomultiplier and is digitized
• The residual image is erased from the plate by an
intense light source, which returns all electrons to
their original state. This makes the plate ready to be
reused for new exposures

24. • The storage phosphor plate fits inside a standard
size cassette and is exposed to X-rays exactly
like film
• The X-ray energy is stored on the plate in the
form of latent energy
How is a Storage Phosphor plate
exposed?

25. • Before exposing the cassette, the patient
demographic and exam data is stored on the
microchip attached on cassette
• This is done by inserting the cassette in a
slot of ID station and entering the data with
the help of keyboard
• When cassette is inserted in digitizer after
X-ray exposure, the digitizer reads both
patient data as well as X-ray exposure data
• The two data are combined to display
images along with patient data

26. • The plate is inserted into the digitizer
where it is scanned with a high power
laser
• The laser light causes the storage
phosphors to release the energy they have
captured in the form of blue light
• In the digitizer, this blue light energy is
converted to electrical signals which are
then digitized to produce digital images

27. • After exposure and scanning, the phosphor plate is
"erased" by exposing to a bright light exposure
within the digitizer
• The previous image stored in the phosphors is
removed and the plate is ready to be exposed again

28. • The digitized image
data is processed on
a processing server
and is displayed on
its monitor

29. • The life of a phosphor plate depends on how
carefully it is handled. Physical damage to the
plate will limit its useful life
• If properly cared for, a plate will produce
thousands of images
• Imaging Plates are known to last more than
50000 Exposure Cycles

30. • No, CR uses the existing X-ray equipment
• One CR system can support multiple x-ray
rooms

31. • Instead of taking the film cassette to a dark room
for processing, the technologist takes the cassette
with imaging plate to the CR reader for digital
processing of the image
• Instead of manually taking the films to the
reporting radiologists , the softcopy images reach
the workstation almost immediately

32. • The time required to acquire a Digital image is
much less compared to conventional darkroom
process
• The film is the first product in Conventional
where as the film is the last product in CR

33. Rx
Network
Digitizer
Printing
MATRIXLR 3300
Identification
Processing server
Exposure
Cassette with Imaging Plate

34. Rx
Network
Digitizer
Printing
MATRIXLR 3300
Identification
Processing server
Exposure
Cassette with Imaging Plate
The cassettes fit into X-ray table. After the exposure, the cassette is identified in the ID-station. Here patient
and exam related information is stored. Next the digitizer reads the identification data, handles the plates, reads
the image and sends out a raw dataset in DICOM-format. The automatic processing server processes the image
according to the type of exam. For each type of exam, an optimized image processing parameter set-up is used.
The processing server then pushes the processed image to the preview station for previewing. After approval
the image is routed to other destinations such as a printer, a review station and an archive server.

35. This technique is performed by digital X-ray
machines with flat panel detectors

36. Digital Radiography uses two types of
detectors:
• Direct
• Indirect

37.  TFT = THIN-FILM TRANSISTOR ARRAY

38. Uses a two step
process that first
converts X-rays
into light, then
converts that
light energy into
electronic signals

39. • Direct detectors automatically convert
X-rays into electronic signals.
 X-rays interact with semiconductor
material
 Amorphous selenium
 X-rays converted directly into
electrical charge
 No intermediate steps

40. • The flat panel detector consists of an amorphous
selenium semiconductor X-ray absorber coating
over a thin-film transistor array of amorphous silicon
• In this system,X-ray photons are immediately
converted into electronic signal
• This immediate conversion eliminates the need for
additional steps to capture and convert incident X-
ray energy
• Corrective image processing which can result in
increased image noise is reduced with the highly
efficient X-ray energy conversion of direct DR

41. • Film has a limited exposure latitude i.e less detail
contrast
• Time consuming & cumbersome
• Intolerant to exposure errors
• Repeat X-rays ( More radiation exposure )
• Film wastage

42. • Cannot be duplicated without loss of quality
• Film storage is a problem
• Scatter radiation reduces contrast and increases
patient dose
• Quality control is an issue

43. • Post processing (soft tissue and bony details can
be viewed at same time )
• Reduction in hazardous X-ray dose to patients
• More info on one image
• Constant image quality
• Possibility of viewing X-ray images wherever
needed

44. • Digital images are of extremely high quality
• Digital images have a future scope of better
image management
• Facility of giving multiple images of
investigative studies on a single high definition
laser film

45. • Radiography consists of following functions:
-Image data acquisition
-Image processing
-Reproduction of image
-Storage

46. • In Screen film system, all the processes are done
on the X-ray film itself which is used for:
-Image data acquisition
-Image reproduction
-Storage

47. On the other hand, Digital X-ray distributes all the
processes into different stages:
• Imaging plate and digitizer are used for
image data acquisition in CR and Amorphous
Selenium detector array in DR
• Processing server is used for image processing and
storage
• Workstation monitor is used for image reproduction

48. • Digital X-ray is the only film less way to link the
existing general radiography set up into the
digital environment of PACS

49. • Image enhancement
• Printing
• Annotation
• Black border
• Panoramic dental package
• Full leg / Full Spine

52. • Image pre-processing
• Scale the data to appropriate range
• Contrast enhancement – Anatomy specific
grayscale manipulation
• Spatial frequency enhancement

56. MISS.PADMINI 20YRS,F 14/08/2004 20:15:01
SKULL, MASTIODS 23
MISS.PADMINI 20YRS,F 14/08/2004 20:17:01
SKULL, MASTIODS 23
MISS.PADMINI 20YRS,F 14/08/2004 20:15:01
SKULL, MASTIODS 23
MISS.PADMINI 20YRS,F 14/08/2004 20:17:01
SKULL, MASTIODS 23

59. DIGITIZER, EMERGENCY 1O/07/2004 22:3O:28 DIGITIZER, EMERGENCY 1O/07/2004 22:3O:28

61. MR.RAVINDER 33YRS, M 19/08/2004 14:20:08
RIGHT LEG, AP&LAT 268
MR.RAVINDER 33YRS, M 19/08/2004 14:20:08
RIGHT LEG, AP&LAT 268

62. MRS.SWAPNA 30YRS, F 29/06/2004 09:15:32

63. MRS.FARIDA 30YRS ,F 12/8/2004 09:15:23
BARIUM MEAL FOLLOW THROUGH 286

64. CR
 imaging plate
 Processing is done in a
Digital Reader
 Signal sent to computer
 Viewed on a monitor
DR
 transistor receiver (like
bucky)
 directly into digital
signal
 seen immediately on
monitor –