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
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
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
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
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
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
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
45.
46.
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
50.
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