chapter 8 radio
purpose of digital image
image produced are diagnostically better equivalent or better compared to film based imaging
use of digital image
to generate images that diagnosis assessment of dental disease
use of digital imaging
To detect lesions, diseases and conditions of the teeth and surrounding structures
To confirm or classify suspected disease
To localize lesions or foreign objects
To provide information during dental procedures
To evaluate growth and development
To illustrate changes secondary to caries, periodontal disease, or trauma
To document the condition of a patient at a specific point in time
To aid in the development of a clinical treatment plan
digital imaging
A method of capturing an image using a sensor, breaking it into electronic pieces, and presenting and storing the image using a computer
Image used to describe the pictures that are produced
A sensor placed inside the mouth
The electronic signal is digitized
radiation exposure
-Digital imaging requires less x-radiation exposure than film-based imaging
-The typical sensor is more sensitive to x-rays than conventional film
-Exposure times are 50% to 90% less than that required for conventional radiography (ALARA principle)
IF digital imaging is less x-radiation does a patient have to wear a lead apron?
equipment
-X-ray unit
-Sensor
.Charge-coupled device (CCD)
.Complementary metal oxide semiconductor/active pixel sensor
.Charge injection device
-Computer
x-ray unit
-Most digital imaging systems use a conventional dental x-ray unit as the x-radiation source
-The x-ray unit timer must be adapted to allow exposures in a time frame of 1/100 of a second
sensor
-a small detector that is placed in the mouth of the patient and used to capture the dental image, various sizes
-wired----> the imaging sensor is linked by a fiber optic cable to a computer
-wireless---> the imaging sensor is not linked by a cable
sensor--> charge coupled device (CCD)
the most common image receptor used in dental digital imaging.
-----> a solid-state detector that contains a silicon chip with an electronic circuits embedded in it
-----> the electrons that make up the sillicon CCD can be visualized as being divided into an arrangement of blocks or picture elements known as pixles
pixel-> a small box into which the electrons produced by the x-ray exposure are deposited
CCD
-The x-ray photons that come into contact with the CCD cause electrons to be released from the silicon and produce a corresponding electronic charge
Each pixel arrangement, or electron potential well, contains an electronic charge proportional to the number of electrons that reacted within the well
Each electronic well corresponds to a specific area on the linked computer screen
computer
Used to store the incoming electronic signal
Converts the electronic signal from the sensor into a shade of gray that is viewed on the computer monitor
The computer digitizes, processes, and stores information received from the sensor
An image is recorded on a computer monitor in 0.5 to 120 seconds
Has split screen and magnification capability
types of digital imaging
-direct imaging
-indirect digital imaging ----> scanning traditional images,storage phosphor imaging
direct digital imaging
-components include an intraoral dental x-ray unit, a sensor,and a computer with imaging software
---> a sensor is placed into the mouth of the patient and exposed
----> the sensor captures the image an transmits it to the computer monitor
---> software is used to enhance and store the image
indirect digital imaging
components include a CCD camera and computer
--> an existing x-ray film is digized using CCD camera
--> the image is displayed on a computer monitor
--> scanning of the image ,copy
storage phosphor imaging
a wireless digital imaging system
--> this a reusable imaging plate coated with phosphors instead of a sensor with a fiber optic cable
--> the phosphor coated plates are flexible and fit into the mouth
--> high-speed scanner is used to convert the information into electronic files
--> this type of digital imaging is less rapid than direct digital imaging
intraoral sensor preparation
Each sensor is sealed and waterproofed
--->The sensor must be covered with a disposable barrier because it cannot be sterilized
Rigid digital sensors, wired or wireless, must be covered with a disposable barrier sleeve
--->Rubber finger cot may be placed underneath the disposable barrier sleeve to further protect the wired or wireless sensor, and to prevent cross-contamination
intraoral sensor placement
the sensor is held in the mouth by bite-block attachments or devices that aim the beam and sensor accurately
--> the paralleling techniques is the preffered exposure methods
advantages of digital imaging
Superior gray scale resolution --> 256 colours of gray to conventional 16 - 25
Reduced exposure to x-radiation---> 50%-90%
increased speed of image viewing
lower equipment and film cost
increased efficiency
enhancement of diagnostic image--> ability to manipulate the density
effective patient education tool
eco-friendly tool
disadvantages of digital imaging
intail set-up costs
image quality
sensor size and thickness--> bulky and less flexible
infection control--> sensors cannot stand heat for sterillization
wear and tear
legal issues--> possibility of digital enhancements