Conventional versus digital/ dental implant courses

CONVENTIONAL
VERSUS DIGITAL
RADIOGRAPHY
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

Why do we take
radiographs?

Role of Radiographs
 Clinical examination
 Diagnosis (confirm / exclude)
 Treatment planning
 During treatment
 Follow up after various treatment procedures

www.indiandentalacademy.comwww.indiandentalacademy.com
Indian Dental academy
• www.indiandentalacademy.com
• Leader continuing dental education
• Offer both online and offline dental
courses

General dentistry:
 Loss of tooth structure
 Carious (occlusal, proximal)
 Non - carious (attrition, abrasion, erosion, fracture)
 Periodontal disease
 Endodontic disease
 Impacted teeth
 Trauma (root and alveolar fractures, foreign bodies)
 Other pathology affecting bone

X-RAY
 DISCOVERED AND
NAMED BY DR. W. C.
RÖNTGEN AT
UNIVERSITY OF
WÜRZBURG, 1895
 AWARDED FIRST
NOBEL PRIZE FOR
PHYSICS, 1901

RADIOLOGY TOOLS
X- RAY
ULTRASOUND
NUCLEAR MEDICINE
MAGNETIC RESONANCE
COMPUTED TOMOGRAPHY

X- RAY
 HIGH ENERGY PHOTON
 IONIZING RADIATION
 EXPOSES FILM / DETECTOR
 PROJECTION DATA

COMPUTED
TOMOGRAPHY
 HIGH ENERGY PHOTON
 IONIZING RADIATION
 EXPOSES DETECTOR

COMPUTED TOMOGRAPHY
 In 1972 Godfrey Hounsefield announced the
invention of revolutionary imaging technique
which he called as computerized axial
transverse imaging.
 Basic concept: Thin cross-section of head, a
tomographic slice, examined from multiple
angles with pencil like x-ray beam and then
transmitted radiations received on the
detectors and then displayed on the computer
as a tomographic image.

CONVENTIONAL
RADIOGRAPHY

Conventional Radiography and
Digital Imaging
 Conventional radiography uses radiographic
film as the image detector

X-RAY FILM
Composition
Emulsion – Silver halide grains and gelatin
Adhesive layer – serves to attach emulsion to base
Film base – polyester polyethylene terephalate
provides stable support to emulsion
Protective layer – transparent coating over emulsion
to protect mechanical and processing damage

FORMATION OF LATENT IMAGES

DEVELOPER SOLUTION
 DEVELOPER - Phenidone, Hydroquinone (silver halide
crystals to metallic silver grains)
 ACTIVATOR - Sodium or potassium hydrozide
Buffer- sodium bicarbonate (gelatin to swell so
developing agents reaches emulsion and to suspended silver
bromide crystals)
 PRESERVATIVE - Sodium sulfite
 RESTRAINER - Potassium bromide, Benzotriazole ( To
depress reduction of exposed and unexposed crystals)

FIXER SOLUTION
 CLEARING AGENT - HYPO (AMMONIUM
THIOSULPHATE)
 ACIDIFIER - Sulfuric acid(acidic PH required for good
diffusion of thiosulphate into emulsion and silver thiosulphate
complex out of emulsion)
 PRESERVATIVE - Ammonium sulphite (prevents
oxidation of thiosulphate)
 HARDENER - Aluminum sulphate (prevents damage to
gelatin, reduces swelling of emulsion, limits water absorption
and shortens drying time)

MANUAL PROCESSING
 Development
 Rinsing
 Fixing
 Washing
 Drying

AUTOMATIC PROCESSING
 Time saving- 4-6min
 Daylight loading
 Rollers – uniformity of processing
 Forcing solution out of emulsion
 Minimizes carryover of developer
to fixer tank

Processing Errors

The term digital in digital imaging refers to the numeric format
of the image contents
 Digital radiography – a film less imaging system a
method of capturing a radiographic image using a
sensor, breaking it into electronic pieces, and
presenting and storing the image using a computer
 Sensor – a small detector that is placed to capture a
radiographic image

Basic equipment
 X-ray source
 Sensor / Detector
 Computer

Figure 1: Intraoral charge-
coupled device
Figure 2: Intraoral charge-coupled
device with plastic infection
control sleeve in place.
DIGITAL RADIOGRAPHY

Charged Couple Device (CCD)

Wireless

Basic structure of CCD
Scintillator – improves x-ray
capture efficiency
Fibreoptics – improve
resolution

 Pixel (picture element) – a discrete unit of
information.
 A digital image consists of a large collection of pixels
organized in a matrix of rows and columns

Formation of a Digital image
 At each pixel of an electronic detector, the absorption
of x-rays generates voltage
 More x-rays – more voltage
 Analog Signal
 Analog to Digital Conversion (ADC)

Schematic representation of
a digital image
X-ray shadow
Image as detected by the digital
sensor; each square is a pixel

Schematic representation of a
digital image
Numerical representation of pixel
values sent to the computer
Digital image on the computer
screen

Direct digital imaging
 Components
X-ray machine, sensor & a computer monitor
Sensor placed inside the mouth
Exposed to x-ray
Capturing of radiographic image by the sensor
Transmission of an image to the computer
Appearance of image in a computer

Complementary Metal Oxide
Semiconductors (CMOS)
Silicon based semiconductor
 Each pixel is isolated from neighbouring pixel and
is directly connected to transistor
 The charge is generated after the x-ray exposure
is transferred to the transistor as a small voltage
Voltage is read by Frame grabber
 Stored and displayed as a digital grey value
 Technology is less expensive than CCD
 Manufacturer – Schick technologies and claims
25% greater resolution and has greater durabilitywww.indiandentalacademy.com

PHOTOSTIMULABLE PHOSPHOR
PLATES(PSP)
ScanX laser scanner
Storage phosphor plates are
inserted at the top of the
scanner (top arrow) and
ejected (bottom arrow) after
scanning is complete

STORAGE PHOSPHOR
PLATES
 Wireless digital radiography system
 Consists of reusable imaging plate coated with
phosphor instead of sensor
 Flexible, fits into the mouth as a conventional
film Phosphor material – Europium-doped
Barium halide (fluoride/iodide/chloride)
 Less rapid than direct digital imaging

Mechanism
Exposure to x-ray source
Records diagnostic data on plates
Plate removed from mouth
Placed into an electronic processor
Laser scans the plate
Produces an image
Image transferred to computer

DIAGRAM STIMUABLE
PHOSPHOR

READING PHASE & A/D
CONVERTER

Advantages
 PSP plates are reusable
 Image acquisition and display are separate
events
 Underexpose or overexposure of PSP can
produce diagnostically acceptable image
 Dental film , image quality decreased greatly
with decreasing exposure, but with PSP image
quality remained same with 53% reduction
exposure
PPR system provides reliable endodontic
measurements even at low exposure

Extra Oral Digital Radiography

Advantages of Digital Imaging
Systems
 50% to 80% less radiation to the patient
 Increase efficiency because images can be viewed
instantly, facilitating a quicker diagnosis and treatment
plan
 Create records that can be electronically transferred
to the patient's insurance company or specialist
 Allow image enhancements, such as sharpening the
image and changing its contrast, lightness, and
darkness
 Provide an educational tool to explain dental
problems and treatment options to patientswww.indiandentalacademy.com

Advantages of Digital Imaging
Systems
 Eliminate the need for a darkroom, film
processor, and processing chemicals
 Eliminate the need to dispose of environmentally
hazardous wastes, such as fixer and lead foil
 Eliminate the high cost of chemical disposal and
film purchases
 Eliminate the need for film duplication because
images can be reprinted
 Reduce the need for paper.

IMAGE STORAGE
 Digital radiographs, and other digital medical
images, are stored as digital data.
 Rapid storage and retrieval
 Less physical storage space required
 Ability to copy and duplicate without loss of
image quality
 Back up media suitable for external storage
media include Hard disks, Digital tapes, CDs,
and DVDs

PATIENT INFORMATION
SYSTEM
 The Patient Information System, perhaps known as
the Radiology Information System (RIS), is an
adjunct to the basic digital radiography
system. Through the interface, information such as
patient ID, scheduling, actual procedures
performed… transferred.

COMMUNICATIONS NETWORK
 Another advantage of digital images is the ability to
transfer them from one location to another very
rapidly.
 This can be:
 Within the imaging facility to the storage and display
devices
 To other locations (Teleradiology)
 Total network available for transferring digital images
is made up of a variety of integrated systems

It is simply a breakthrough in the world of dental services.
Other Application Softwares

TELERADIOLOGY
 Allow direct digital or digitized film images to
distant locations , where they can be viewed and
downloaded to hard copy for reading and
interpretation
 Acceptance of transmitted images by insurance
companies has shortens the authorization time for
patient treatment and speeding reimbursement to
the practitioner
 Commonly used format for transmission of images
is the Tagged image format file (TIFF), Wide area
network (WAN) www.indiandentalacademy.com

TELERADIOLOGY
 To improve transmission speeds , data compression
is done preserving critical image information
 Most widely used lossy compression versions are of
3.0 DICOM (Information modeling, technology, and
communication protocols)
 JPEG (Joint photographic Experts Group)
 Wavelet compression
 Advantage of saving interms of time and cost with an
increased demand for health care in undeserved
urban and rural areas will facilitates the acceptance
of Teleradiology www.indiandentalacademy.com

DICOM AND DENTISTRY
 Digital Imaging and Communications in
Medicine
 Standard specification describes a means of
formatting and exchanging images and
associated information
 It relies on media devices which address
communication and storage of digital images
from diagnostic modalities like CT, MRI, PET,
Nuclear medicine, Ultrasound, DR, Digitized
radiographs…
 Interconnectivity is imp to cost – effectiveness

DICOM
 Medical/ dental images can be captured and
communicated quickly, physicians can make
diagnosis and treatment vendors can be
made sooner
 Reimbursement for therapy can be enhanced
 Goals – facilitates operation in a networked
environment
 Structure to accommodate the introduction of
new services
 Make use of existing standards wherever
applicable

Dental imaging modalities are
supported by DICOM
 Digital intraoral endoscopes
 Digital intraoral radiography systems
 Digital panoramic systems
 Digital cephalometric machines
 Extra oral digital photographic systems
 Microscopic imaging systems for Oral
pathology

DICOM
 DICOM – I.O.P.A serves as
 An Acquisition medium during radiographic
procedure
 A Display medium for review and diagnosis
following procedure
 An Interchange medium b/n clinics and
dentists
 An Archive medium for long term storage of
patient records

VIDEOCONFERENCING
Conducting a conference between two or more
participants at different sites by using computer
networks to transmit audio and video data.
Multipoint videoconferencing allows three or
more participants to sit in a virtual conference
room and communicate as if they were sitting
right next to each other.
Other terminologies:
Data conferencing
ISDN (Integrated Service Digital Network)www.indiandentalacademy.com

DISPLAY
 Other advantages include the ability to zoom,
compare multiple images, and perform a variety of
analytical functions while viewing the images.
 Compared to radiographs recorded and displayed on
film, i.e. "softcopy", there are advantages of
"softcopy" displays
 Digital images cannot be lost or misplaced
 One major advantage is the ability of the viewer to
adjust and optimize image characteristics such as
contrast

Comparison Of Different X-ray
Detectors Used In Dentistry
 Essential properties of any digital imaging should
have
1. image produced should be of diagnostic quality
2. radiation dose is equal or reduced compared film
3. Digital radiology techniques should be compatible
with conventional x- ray generators
4. Lossless archiving is allowed in an image file
format that promotes interoperability within
DICOM standards
5.Time required for total procedure should be equalwww.indiandentalacademy.com

Comparison Of Different X-ray
Detectors Used In Dentistry
 Spatial resolution - Capacity for distinguishing
fine details
 Currently highest resolution CCD detectors for
dentistry have pixel sizes of approx 20 µ
 Silver grain for an intraoral film – 8 µ
 Resolution measurement – line pairs per mm
 Highest spatial resolutions were found in
InSight film, RVG- ui High resolution mode and
RVG 6000 detectors(20 lp/mm)
 www.indiandentalacademy.com

 Latitude – ability of an imaging receptor to capture
a range of x-ray exposures
 Ability to record the full range of tissue densities,
from gingiva to enamel
 Useful range of densities in film radiography – 0.5 –
2.5
 Latitude of CCD and CMOS is similar to film
 PSP have larger latitudes
 Current detectors perform well interms of spatial,
contrast resolution and in exposure latitude
 Dental X-ray generators should be modified to
provide lower exposure options when exposing
digital x-ray detection systems (OOOOE

Conventional Vs Digitized
radiographs Image quality
assessment
 Density- Densitometer
 Contrast – Density differences b/n exposed and
unexposed sides of film
 Resolution – 2x magnifying glass
 Density of digitized radiographs are higher than
conventional film for the same exposure time
 Contrast of digitized radiographs are higher than
conventional film for the same exposure time
 Resolution was similar for both images
(Dentomaxillofacial Radiology 2005, 34; 353-www.indiandentalacademy.com

Diagnosis of Periapical bone lesions
 An image analysis system was developed for
computer aided diagnosis of periapical bone
lesions in the dental radiographs.
 Identify periapical region
 Trabecular pattern detected by texture analysis
 Determine presence of periapical lesion
 Estimate the size of lesion
 A. Mol, P. F. Vander Stell
1992

Diagnostic comparison of direct dental
radiography for the detection of periapical bone
loss
 Direct digital radiography(DDR) – RVG, Sens-A-
Ray, Visualix, Flash Dent, CDR and SIDEXIS
(Siemens)
 AD- Dose reduction, immediate image display, and
image processing facilities
 Draw back – Small image area, except for CDR
sensors, which are comparable to film size
 High – contrast resolution of the DDR system was
inferior to the conventional film
 Low- contrast resolution RVG system presented
higher sensitivity than D and E- Speed filmswww.indiandentalacademy.com

Diagnostic comparison of direct dental
radiography for the detection of periapical bone
loss
 comparison of direct dental radiography for the
detection of periapical bone loss showed no
differences between D and E-Speed films and
Sens – A- Ray system
(OOOO 1996;82:344-50)

ADVANTAGES OF DIGITAL O.P.G
 Higher efficiency of electronic sensors makes a
substantial reduction of X- ray dose to the patient
 ALARA – To implement new technologies which
makes this standard a reality
 Pixel intensity, Fractal analysis(mathemetical
methods for describing and analysing complex
shapes and patterns of cancellous bone on dental
images) for detecting osteoporotic changes in
mandibular C/PM region cancellous bone on CCD
digital images by using image analysis.
 Dis – Radiographic shadows of overlying structures
like cervical spine, will be sharper than

ADVANTAGES OF DIGITAL
EXTRAORAL IMAGING
 Common projection is of cephalometric – method
for ascertaining cranio mandibular growth and
skeletal relationships
 To locate automatically the anatomical landmarks
for cephalometric analysis which would
eliminate tracing of radiographs and manual
localization of landmarks
 Results would be of reproducible and reliale
(Digital Panaromic and Extraoral Imaging ,
DCNA , Vol 37 , OCT 1993, 541-545)

Computer Assisted Diagnosis:

Film and Digital radiography for
detection of simulated root resorption
cavities
 External root resorption can be seen as a
complication of trauma, transplantation, and
Orthodontic movement of teeth
 With optimal exposures film, CCD could not be
considered as adequate technique to detect early
resorption
 Storage phosphor system has considerably
diagnostic value at lower exposure values
(Film and Digital radiography for detection of
simulated root resorption cavities, OOOO
1998;86:110-4)

A comparison of PSP digital images with
conventional radiographs for the clarity of fine
endodontic files and periapical lesions
 An accurate working length is an effective
canal debridement and root canal obturation
 Non vital teeth with periapical lesions that
were instrumented and filled within 2mm of
apex had highest success rate of 94%
 Radiographs do not always reflect the extent
of the destructive process in the periapical
tissues and under represent the size of lesion .
It require loss of lamina dura before
radiographic detection of a periapical lesion
can occur www.indiandentalacademy.com

 DDR has ability to manipulate image after
acquitisation to produce a more clear diagnostic
image, reduction in the b/n exposure and image
interpretation, and ability to electronically store
patient records
 Digital images were inferior to E-Speed films in
terms of clarity of endodontic file tips in relation to
root apex
 Use of enhanced mode resulted greater clarity of
file tip compared original image
 Storage phosphor system imaging were more

A comparison of PSP digital images with
conventional radiographs for the clarity of fine
endodontic files and periapical lesions
 Digital radiography offers no advantage over
conventional film with respect to ability of
detecting periapical lesions
(OOOOE 2002;93:321-7)

Effects of Dose reduction on the detect ability
of Standardized Radiolucent lesions in Digital
O.P.G
 Orthophos DS can be used by a dose reduction
of upto 75% compared to Kodak Ektaspeed films
to detect ability of Standardized Radiolucent
lesions with a diameter of 1 or 1.25 mm
(OOOO 1998; 86: 227-33)

Comparison of O.P.G and Digital subtraction
radiography in the detection of simulated
osteolytic lesions of Mandibular condyle
 Imaging of TMJ made with negative vertical –
beam angulations, X-ray beam is not parallel with
long axis of the condyle , which makes
superimposition of base of skull and zygomatic
arches
 Anatomic relationships of bony structures of the
TMJ are not accurately depicted on O.P.G
 Digital subtraction radiography effectively used to
improve visualization of condyle
 Color enhanced DSR shown improved diagnostic
capabilities in the detection of simulatedwww.indiandentalacademy.com

Periodontitis Detection Efficacy Of
Film and Digital Images
 Alveolar bone height
 Alveolar bone health
 Generalised vs localised
alveolar bone loss
 Peri-radicular infection
 Electronic automatic probes, manual probing,
Bitewing radiographs, digital images – Holds there
were no differences in diagnostic efficacy with
respect to alveolar bone level assessment
(Periodontitis Detection Efficacy Of Film and
Digital Images, OOOO, 1998;85:608-12)

Quality of Film- based and Digital
O.P.G
 Visualization of anatomical structures being worse in
digital than film images (overexposed areas of
mandibular rami and body )
 Film images of T.M Joint to be better than digital
images obtained with storage phosphor and CCD
system
 More noise in digital images
 Ad- fast image communication, small storage space,
decreased pollution of environment
 By the use of greater image depth (10 or 12 bits )might
improve quality(Quality of Film- based and Digitalwww.indiandentalacademy.com

Common Electronic Image Processing tools
used for various diagnostic purposes
 Interproximal caries detection- Contrast and
brightness optimization and embossing
 Alveolar crestal bone height- optimizing
contrast and brightness can help measure
alveolar bone height , image reversal also
seems to allow better visualization of PDL
space, Furcation areas, and even pulp canals
 PDL Width – Image inversion, embossing tools

Common Electronic Image Processing
tools used for various diagnostic
purposes
 Early periapical changes – to detect in these
changes in a conventional film 30% of cortical
bone must be destroyed, but this is not the
case in a digital film

COMPUTERISED
TOMOGRAPHY
 Other radiographic methods provides two
dimensional view where as CT provides three
– dimensional object
 Each slice can be viewed individually so that
superimposition of structures can be
minimized
 CT imaging can be electronically processed
without altering original image

DENTAL APPLICATIONS
 Radiological examination of pathological
processes and assist the surgeon in treatment
planning
 Assessment of para nasal sinuses
 Assessment of trauma, TM Joint
 Implant assessment

CONE BEAM CT
 4 manufacturers are currently available
toprovide this technology
 3 – “Sit- down” panoramic type and 1
traditional “table – gantry “ type of CT
 Devices allow oral radiologists to acquire
images of only the head and neck region of
patient , at greatly reduced absorbed x-ray
doses compared to conventional medical CT

Tuned aperture computed
tomography (TACT)
 Assessment of dento alveolar tissues in three
dimensions with existing dental equipment without
the high cost and dose associated CT
 By shifting and combining a set of basic projections
 Each radiograph is taken at different angles relative
to object and receptor
 Improves ability to detect osseous defects around
implants
 TACT subtraction used to detect and localization of
osseous changes in the crestal bonewww.indiandentalacademy.com

DIGITAL SUBTRACTION
RADIOGRAPHY
 Is a useful method for assessing the small
differences on serially taken radiographs
 It was facilitated by development of
microcomputer allowing conventional to be
digitized and subtracted
 To evaluate Periodontal changes, Diagnosis of
periapical lesions , Evaluation of external root
resorption, diagnosis of proximal caries and
evaluation of bony changes surrounding implants
 Many studies showed that DSR was superior to
conventional radiography for evaluation of bony

DIGITAL SUBTRACTION
RADIOGRAPHY

DIGITAL SUBTRACTION
RADIOGRAPHY
 Quantitative analysis of apical root resorption
can be performed by means of DSR using
Emago software. Calculated value was equal
to amount of tooth loss(ooooE 2001;91:369-
73)

DSR
 To minimize these errors an automatically
registration method based on cross-correlation
of a region of interest (ROI) in this surrounding
anatomical region of interest provides higher
accuracy than bone patterns using larger ROI
(OOOOE;2006:101, 503-6)
 Discrepancy of projection geometry is the main
cause of errors in subtraction images of DSR
 To reduce this several paralleling techniques
developed, such as bite block, film holder, beam
aiming device. www.indiandentalacademy.com

DSR
 Most reproducible instrument to produce
diagnostically useful information for DSR is
combination of elastic impression maerial and
XCP bite block.
 Vertical angulation error was larger than
horizontal
 Vertical angulation error was smaller in
mandible than maxilla, and placing sensor was
easier in mandible than in mxilla.

 Advantages 0f Digital Radiography over
conventional film-based radiography
 Lower dose of radiation required
 Computer manipulation of the image resulting
in:
Alteration in contrast
Alteration in resolution
Image enhancement
Automated image analysis

Disadvantages of Digital Imaging
Systems
 High initial set-up cost, though the cost is recovered
over several years
 Sensor’s active area is smaller than intra oral film
which limits the number of teeth shown in each
exposure
 May compromise patient comfort because the
sensors are bulkier than conventional film, except
when using PSP plates
 Cable can make the placement of the sensor in the
mouth difficult
 Requires the use of barrier protection for infection
control because the sensors cannot be sterilized
 Time lost to training the entire staff to use the system

Disadvantages of Digital
Imaging Systems
 May cause legal issues because of the
capability of the system to enhance the images;
a system must have an archival DICOM 3
compliant storage protocol
 Fragile sensors are expensive to replace
 Inferior image quality with a resolution of 10 line
pairs per mm compared with conventional film
that has a resolution of 12 to 20 line pairs per
mm

Disadvantages
 Expensive, especially panoramic systems
 Large disc space is required to store the images
 In direct digital systems the sensor and the
computer have to be connected directly, and the
connecting cable can make intraoral placement
of the sensor difficult
 There is some loss of image definition and
resolution compared with film, both on the TV
monitor and the hard copy printout

Disadvantages
 Image manipulation can be time-consuming and
misleading to the inexperienced
 It is difficult with some intraoral systems to view
multiple images at once, e.g. a full mouth survey
 The hard copy images can fade with time-this
may be a major problem since a radiograph
taken of a 6-year-old child legally should be kept
until the patient has reached 25

REFERENCES
 Christensen’s Physics of Diagnostic Radiology,
4th edition.
 Fundamentals of X-ray and Radium Physics,
Joseph Selmon, 8th edition.
 Oral Radiology-Principles and Interpretations,
Stuart C. White & Michael J. Pharoah, 5th
edition.
 Essentials of Dental Radiography and
Radiology, Eric Whaites, 2nd edition.
 Physics of Radiology, Meredith.
 Oral Surg Oral Med Oral Pathol Oral Radiol
Endod 1984:338-342.

 Dentomaxillofac Radiol 1993:22(1); 7-12.
 Dentomaxillofac Radiol 1993:22(1); 179-182.
Endod 1995:79: 114-116.
 Dentomaxillofac Radiol 1999:28; 73-79.
 The Dental Assistant 2003:72(5); 22-28.
Endod 2001: 91; 120-129.

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Conventional versus digital/ dental implant courses

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