Recent advances in diagnostic aids /certified fixed orthodontic courses by Indian dental academy

Recent Advances in
Diagnostic Aids
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


1

History
Andreas Vesalius (1514-1564) published
his masterpiece De Humani Corporis
Fabrica in 1543.

Discovery of X rays- Roentgen


2

History

W C Roentgen
First human radiograph
3
(1845-1925) www.indiandentalacademy.com

History
Original Orthodontic diagnostic
records
- Study models
- Detailed clinical examination
- Plaster models of face
- Radiographs –
Cephalometric,panoramic
- Photographs

5

Fundamentals of Diagnostic
Imaging
Different approaches to diagnostic
imaging –
Transmission imaging
Reflection imaging
Emission imaging


6

Imaging and Image acquisition

Images

Conventional
ANALOG PROCESS

Contemporary
DIGITAL PROCESS


7

Digital Imaging
Digital Photography
Digital Radiography


8

Digital Photography
Digital camera


9

Digital Photography
Basic structure


10

Digital Photography
Image acquisition


11

Digital Photography
CCD - Charged Couple Device (Charge
Coupled Device?)
CMOS – Complementary Metal Oxide
Semiconductor
ADC – Analog to Digital Converter
Light

Sensor
Memory

Electric charge


ADC

12

Digital Photography
Image quality –
Pixel (Picture element)

Voxel (Volume element) &
Spoxel (Space element)

13

Digital Photography
Storage of digital images
Compression –
JPEG (Joint Photographic Experts Group)
TIFF (Tag Image File Format)
Compression ratio – 3:1 almost no loss
20:1 clinically acceptable
Storage media- Magnetic disks
Optical or laser disks
Optical tape – 1 terabyte (1 million
14
MB)

Digital Photography
Advantages of digital photography
- Instant viewing of pictures – mistakes
can be rectified immediately
- No film or processing is required
- Manipulation of data on computer
- Organization of data
- No rolls – saves money in long run
- Decreases storage needs
- Transmission of data

15

Digital Radiography
Digital radiography is possible since
Trophy introduced the first Charge coupled
device (CCD) in mid- 80’s
Patient radiation exposure can be reduced
by 30% - 98%


16

Digital Radiography

X Ray

Sensor

Data collection:

Electrical
charge

digitizer

Image

• CCDs
• Amorphous Selenium
• Amorphous Silicon
• Phosphor plates


17

Digital Radiography
RadioVisuoGraphy (RVG)
 Imaging done with a CCD
 view delay 1 - 4 s
 very high resolution
 optimal shape and size of the sensor
 sensor thickness 4 mm
 sensor cable diameter 3 mm


18

Digital Radiography
Structure of the sensor

Scintillator

CCD

Fiber optic layer

19

X-ray imaging with CCD
Scintillator- converts x-radiation
to photons (light)
Fibre optic layer
- conducts photons to CCD
- stops x-radiation
pixels

CCD- converts photons
to electrons (charge)

Electronic circuit
- amplifies the signal
- converts the analog signal
to digital

20

Digital Radiography
DenOptix
- A radiographic technique which
eliminates silver halide film
- Instead uses Storage Phosphor imaging
plates
- Advantage over CCD - no rigid sensors
and wires,also less expensive

21

Thin,flexible films
Low cost laser scanner


22

Phosphor plate:

PROTECTIVE LAYER
PHOSPHOR LAYER

SUPPORT
BACKING LAYER
BAR CODE LABEL


23

Imaging cycle

1.Load intraoral or panoramic
imaging plate

5. Erase imaging plates
for reuse

2. Take X ray

Image on computer


3. Mount imaging plates in carousel

24

4. Place in scanner & Scan images

Digital images can be manipulated using
software filters


25

Advantages
- Alternative to conventional film
- Same machine and settings used for DenOptix
and regular cephs & OPGs
- No dark room required
- Environment friendly- no heavy metal wastage
- Can be reused thousands of times
- Transmission of images
- Saving staff time

26

Digital Cephalometry
Digitization is a process by which analog
information is converted into digital form
- Direct computer digitization of the ceph.
- Indirect computer digitization of the ceph.


27

Indirect digitization
Digitizing tablet

Electronic pen

Mouse

Cross hair cursor

28

Digitizing tablet with cross hair cursor
 Fine electronic grid- 0.009mm
 Two wires arranged in a cross hair pattern
embedded in a glass window


29

Digitization
 Activated by pressing the button
 Location of individual landmarks in a
predetermined sequential manner
 Visual ceph generated by connecting
dots by lines and curves
 Once digitization is complete,any
analysis can be performed in seconds

30

Digigraph
Introduced by Dolphin imaging systems
Non radiographic system
Video imaging is also possible
VTO


31

Digigraph
The Digigraph Workstation
 5 feet long,3 feet wide,
7 feet high.
 working area of 25 sq feet.
 two video cameras –
permanently aimed and
focused

32

Digigraph
Head holder
 More comfortable
 Ear rods and forehead
& posterior head pieces

33

Digigraph
 Model board inserted in
head holder to record
images


34

Digigraph
 Light box can also be attached
for imaging panoramic
radiographs,etc


35

Digigraph

 Attached video monitor –
can be moved
 Images,text,numerical data
can be displayed,stored,
modified using a light pen or
computer keyboard

36

Digigraph
Output devices
 Sony video imager – makes 5”X
7” colour prints in 60 seconds
 Polaroid freeze frame camera –
polaroid prints in 10 seconds
 Hewlett Packard paintjet printermakes 8”X10” colour copies in
4-8 minutes

37

Digigraph
 Digitizing handpiece with
removable,sterilizable tips
 Landmark location is recorded
in 3 dimensional coordinates(x,y,z)
 The time it takes the sound to
reach each of the microphones
determines the landmark location.

38

Digigraph
Procedure
Select cephalometric analysis to be performed


39

Digigraph
Procedure
Digitization


40

Digigraph
Procedure
 Digitizing done in order –
1.Facial landmarks
2.Mouth closed intraoral landmarks
3.Intraoral landmarks requiring a
disposable bite opener to be
inserted
 Indirect digitization –
4.Extrapolated landmarks

41

Digigraph
Cephalometric analysis display
- Any of the 14 cephalometric analyses
• Downs
• Rickets lateral
• Burstone
• Rickets frontal
• McNamara
• Vari-Simplex
• Tweed
• Holdaway
• Grummons frontal
• Alabama
• Standard lateral
• Jarabak
• Standard frontal
• Steiner

42

Digigraph
Tracing display
- Additional custom analyses
may be set up
- Observed value is shown with
patient norm- adjusted for age,
sex,race and head size – and
standard deviations from norm

43

Digigraph
Visual Treatment Objective (VTO)
To move part of the picture,
simply touch the light pen
to two points on the screen,
at opposite extremes of the
area to be moved.


44

Digigraph
The software automatically blends
skin tones and smoothes profile
lines so they are consistent with the
surrounding tissue.

“Before and after" format


45

Digigraph
Finishing the Digigraph session
At this point the data is saved on two 3 ½ "
floppy disks – one given to pt. and the other
disk for office record.


46

Computed Tomography
Introduced in medicine in early 70’s
Slice like images are referred to as tomograms
and a computer is necessary to generate the
pictures; hence the name – Computed
Tomography


47

Computed Tomography
Equipment
- Scanner (movable X ray
table + gantry)
- Computer system
- Display console


48

Computed Tomography
Principle
An image of a layer within
the body is produced
while the images of the
structures above and
below that layer are made
invisible by blurring

49

Computed Tomography
A pencil beam is used in CT


50

Computed Tomography
Scan geometries
- Early scanners – translation+rotation
- Contemporary scanners – rotation only


51

Computed Tomography
Scan geometries


52

Computed Tomography
CT measurement geometry


53

Computed Tomography
Detector system
Two types of detector
i.Ionization chamber
(Gas filled chamber
with electrodes)
ii.Scintillation detectors
(Solid crystalline
dielectric)


54

Computed Tomography
Clinical applications
High radiation exposure and high cost has
prevented its use in Orthodontics.
But in certain situations benefits outweigh risks.
 In severe craniofacial deformities where 2D
diagnostic records are inadequate
 Treatment predictions with 3D computer
tomographic skull models
 TMJ examination


CT image
55

Computed Tomography
TMJ examination
CT for the evaluation of the TMJ was introduced
by Wegener and colleagues for
demonstrating bone abnormalities within the
TMJ.


56

Computed Tomography
TMJ examination
 Useful in determining changes
in bone density
 Primary imaging method when
internal derangement or arthrosis
is suspected – clinical diagnosis
is not always sufficient.
 Has advantages when planning
treatment or operations on jaws
and TMJ diseases and
deformities.

57

Micro Computed Tomography
 Principally the same as CT, except that the
reconstructed cross sections are confined to a
much smaller area.
 Significantly reduces radiation dosage.
 Used to measure bone connectivity in all 3
dimensions and even record anisotropy – till
now not possible even with histology

58

Micro Computed Tomography
Clinically used to evaluate alveolar
remodelling (osteoblastic/osteoclastic activity)
as well as bone dehiscences and root
resorption


59

Magnetic Resonance Imaging

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60

Recent advances in diagnostic aids /certified fixed orthodontic courses by Indian dental academy

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