In this fast growing techo-rich world, we need to have the basics go more stronger to equip ourselves efficiently.

1. “A picture is worth a thousand words”
“Knowledge is valuable”
“Don’t waste it”

2. •INTRODUCTION
•USES, ADVANATAGES, DISADVANTAGES
•EQUIPMENT
•ANALOG TO DIGITAL CONVERSION
•DIGITAL DETECTOR SYSTEMS & CHARACTERSTICS
•DIGITAL IMAGE DISPLAY
•DIGITAL SUBSTRACTION RADIOGRAPHY
•CONCLUSION
•REFERENCES

3.  Technological advancement-Cassetteless system
Method of capturing radiographic Image
Sensor
Break in Electronic pieces
Present and Store
Computer

4.  Detect lesions, diseases, conditions
 Information during root canal
procedures, implants
 Evaluate growth & development
 Changes secondary to
caries,trauma, periodontal diseases
 Progress of treatment

5.  Superior gray scale resolution
 Easy reproducibility
 Reduced exposure to radiation
 Detection of defects & 3D visualization of
dental structures
 Effective patient education tool
 No loss of quality due to chemical processing
 Lower equipment & film cost
 Enhancement of diagnostic image

6.  No Darkroom
 Transmission of Images for Consultation
 Instant Viewing of Images

7.  Initial set up costly
 Sensor size thicker than intraoral film
 Infection control difficult
 Receptors susceptible to rough handling and
costly to replace
 Legal considerations

8. FILM BASED IMAGING DIGITAL IMAGING
 Density-overall degree of  Brighteness-equivalent
darkening
 Latitude- measure of range  Dynamic range: number of
of exposure-distinguish shades of gray i.e pixel
density
 Film speed-faster film-less  Linearity-direct
radiation relationship b/n exposure &
image density
 Contrast-diff in density-  Contrast resolution-small
areas of radiograph diff in density

9.  Resolution-distinguish b/n  Spatial frequency-measure of
resolution-lines pairs/mm
small objects that are close
 Background electronic noise:
together
small electric current that
 Radiographic mottle-app
conveys no information but
of uneven density of an serves to obscure electronic
exposed film/graininess signal
 Sharpness- ability to define  Signal to noise ratio-
an edge/display density Fraction of output signal≈
boundaries diagnostic information(signal) +
signal (no information-noise)

10. INTRAORAL EXTRAORAL
 Direct  PhotoStimulable Phosphor
 Indirect Based radiography (PSP)-
 Storage phosphor imaging computed radiography
 Charged couple device
(CCD) systems-solid state
linear array of
photoiodides

11. DIRECT
INDIRECT

12. • Dental x-ray unit-radiation source
 Same for conventional but adapted to 1/100th
second exposure time
• Sensor-intraroral –no film, extraoral-PSP plates
• Computer-DIGITAL IMAGE DISPLAY

13.  Numeric format of image content & discreteness
• Spatial distribution of picture elements(pixels)
• Different shades of gray of each of the pixels
20
20
15
10 10
C1
0 5
1 2 3 4 5 6 7 8 9 10
0
1 2 3 4 5 6 7 8 9 10
Conventional-continuous Digital-inc /dec
density spectrum

14.  Small box or well-electrons are produced by
x-ray exposure-deposited
 Row/column-coordinate in matrix
 Digital equivalent of a silver crystal
 Ordered arrangement

15.  Sampling- small range of voltage values
grouped together-single value
 Quantization- every sampled signal is
assigned a value
 Stored in computer & represent image-
computer organize pixels-gives shade of
gray-correspond to no. assigned value during
quantization

16.  CONTRAST RESOLUTION
 SPATIAL RESOLUTION
 DETECTOR LATITUDE
 DETECTOR SENSITIVITY

17. • Ability – distinguish - densities
• Interaction of attenuation characteristics of tissues
being imaged
• Ability of computer display to portray diff in density
• Ability of observer to recognize differences
 Noise- densities captured limited by inaccuracies in
image acquisition

18.  To distinguish fine detail
 Limit of resolution-function of pixel size
 Resolution measured- units of line pair per
millimeter
 LINE PAIR(lp) - line & its associated space-
lp/mm
 2 pixels required to resolve a line pair

19.  Ability of imaging receptor to capture a range
of X-ray exposure
 Full range of densities – gingiva to enamel
 PSP receptors – larger latitude
 CCD & CMOS-similar to film-enhanced by
contrast & brightness

20.  Sensitivity of detector to respond to small amt
of radiation
 Factors : detector efficiency ,pixel size, noise

21.  Charge Coupled Device ( CCD)
 Complementary Metal Oxide
Semiconductors(CMOS)
 Photostimulable Phosphor Plates (PSP)
 Flat Panel Detectors(FPD)

22.  Solid state detector–thin wafer of silicon chip
+ electronic circuit
 Sensitive to xrays/light
 Enclosed in plastic housing(protect oral
environment)
 Electronic cable/wire system-fiberoptic cable-
sensor attached to computer-ADC
 Length-8-35 feet

23.  Wireless/cordless system-cable connection replaced
by micowave transmittor
 Pixel size- 20 to70 microns-307,200 pixels
 CCD more sensitive to light than X-rays
 Layer of scintillating material (Gadolinium
oxybromide)coated on the CCD directly/coupled to
surface – fiber optics-inc xray absorption efficiency
 Linear array of Pixel = OPG & Ceph
 More time - complete scan

24. X radiation breaks covalent bonds
b/n silicon atom – electron hole
pairs
“charge packets”-positive potential
Each packet = one pixel
Charge pattern = latent image
“Bucket bridge” fashion-row of
pixel charges to next
End of row-as voltage-Charge
transmitted - ADC

25. High Resolution = 22.5 Standard = 45
Standard High Standard
&
High
Resolution
#2 #1 #0

26.  Silicon based semiconductors-pixel isolation
from neighboring pixel-directly connected
Charge transferred to transistor as small voltage
Read by Frame Grabber
Stored and displayed as digital gray value

27.  Digital cameras, digital dental
radiography, CPU chips
 25 %more resolution, cheap, durable

28.  Similar to CCD, no computer used
 CID xray sensor, cord, plug-inserted into light
source on camera platform-system monitor-
seconds
 Same as intraoral camera
 Color printer

29.  Absorb & store energy from xray- stimulated by light-
app wavelenghth-release energy as light
(PHOSPHORESCENCE)
 “Europium doped” barium fluorohalide
 Crystal lattice- barium+iodine+chlorine+bromine
 Europium-imperfection in lattice
 F-centre

30. Exposed to sufficient energy source
Valence electrons absorb energy-move in conduction band
Electron-halogen vacencies-trapped
Latent image
Red light 600nm-electrons released by barium fluorohalide to
conduction band
When electron returns to europium ion, energy is released in green
spectrum b/n 300 and 500 nm
Red filter at photomultiplier tube selectively removes stimulating
light, & green light converted to voltage
Voltage signal quantified by ADC, stored & displayed as digital image

31. (Europium Activated Barium FluoroHalide)
BaFX:Eu , (X= Cl, Br, or I)

32.  PSP plates –sizes as intraoral and extraoral film
 PSP plate -erased before use - ghost images
 Latent image on PSP plate can be read by:
 Stationary plate scans - rotating multifaceted mirror reflecting
beam of red laser light.( fast & slow scan direction)
 Rotating plate scans – rotation of drum past a fixed laser
provides a scan
 Resolution of PSP systems determined by:
 Thickness of phosphor material
 Diameter of the laser beam

33.  Plates processed quickly
 Susceptible to bending & scratching – permanent
artifacts in receptor – obscure information of
potential diagnostic value
 Semidark environment- plate handling
 Red light- not safe

34. Casette and PSP
PSP digitizer
Workstation

35.  Provide large matrix areas - pixel sizes <100 microns
 Direct digital imaging-Larger areas of body-head
Two types:
 Indirect detectors
 sensitive to visible light
 intensifying screen converts x-rays energy to light
 Direct detectors- photoconductor material(selenium)
Similar to silicon, high atomic no-more absorption

36.  Thin film transistor (TFT)-laptop, flatpanel
computers
 Digitizes, processes, stores-immediate
viewing-good speed
 Dental procedures-root canal, implants
 Hardcopy-printed
 Transmitted electronically

37.  Spilt screen technology-multiple images on
same screen
 Magnification-linear & angular
measurements
 Image restoration-raw data received-
corrected-before visible image on screen
 Image enhancement-brightness &
contrast, sharpness, colour

38.  Image analysis-extract non pictorial
information-segmentation
 Image compression-reducing no. of digital
files.lossy- irreversible
 Image synthesis-CT, MRI, PET-acquired data-
multiple projections-new image-sectioning

39.  Tomosynthesis-selective focusing on an
arbitrary slice-through object-shift & adding
basic projection
 Localized computed tomography(micro CT
radiography, Microtomography)
-invitro-study of mineral tissues
-complex facial fractures
Work as CT

40.  Enhances the mineral changes that have
occurred over time against a homogenous
background of unchanged anatomy
 Subtraction of gray scales-b/n 2 images
 Change-light & dark areas-loss of bone(dark
area), gain (light area)

41.  Subtle changes in bone-before & after
periodontal therapy
 Periapical region
 Condylar changes

42. Subtraction radiography. The image to the right is the result of the
subtraction of the second image from the first image. Note the dark
area indicating bone loss (red arrow) that was not visible on the
original image

43.  The Digital Imaging and Communications in
Medicine (DICOM) Standard is a detailed
specification that describes semantics and
syntax for exchanging images and associated
information. The standard applies to the
operation of the interface which is used to
transfer data in and out of an imaging device.

44. DICOM Display
Workstation
Storage, Query/Retrieve,
Study Component
LiteBox
Query/Retrieve
Results Management
DICOM
Acquisition
Media Exchange Print Management
DICOM Query/Retrieve,
Archive Patient & Study

47.  Film images->digital format->enhanced
Better quality
 2 parts-drum scan with reading & writing
units
 Minicomputer with subsystems
 Ad-overall improved contrast, trabecular fine
marrow spaces, low density=high density
 Disad-artifacts & noise

48.  Microscopic imaging-single frame digital
camera-attach dental microscope-high
quality images
 Intraoral cameras-photo of single
tooth, procedure, documentation & patient
education
barrier sheath-contamination

49.  Fiberoptic imaging-endoscope-root canals
-0.7 mm & 11.8 mm dia light fiberoptic probe-
insert in root canal
-disposable-optical grade plastic
 PSP radiography-trial file length
 Digital photography

51.  Oral Radiology, Principles and interpretation,
5th edition – White & Pharoah
 Text book of Dental and Maxillofacial
Radiology, Freny. R.Karjodkar
 Essentials of Dental Radiography &
Radiology, III edition, Eric Whaites