Chapter 25

Question 1

Digital Imaging

Answer 1

Filmless imaging
A digital radiograph is not an actual picture but a computer’s representation of the image from the computer’s programming. In other words, if it is not in the programming, it will not show up in the radiograph.. The computer can delete or stress different aspects.

Question 2

Indirect Digital Imaging

Answer 2

Converts conventional radiographs to digital via a scanner equipped with a transparency adapter
Or
Via use of a digital camera. Place a radiograph on a viewbox and photograph. The camera digitizes the image and converts
THESE ARE COPIES OF THE ORIGINAL SO CLARITY IS LOST.

Question 3

Direct Digital Imaging

Answer 3

Used to replace the traditional film. It uses special sensors and a computer.

Question 4

What are the goals of Direct digital imaging?

Answer 4

To produce high quality diagnostic images by improving the quality through pixels, spatial resolution, and gray scale.

Question 5

What are the uses if direct digital imaging?

Answer 5

to detect and classify oral disease and lesions, to detect trauma, Eval. growth and development and working films used in end. or surgery.

Question 6

What is Digital Subtraction?

Answer 6

Digitally merging 2 images to show changes that occur over time. The “like” portions cancel each other out and clearly images the differences.

Question 7

What is Pixel?

Answer 7

Short for picture element– discrete units of information that together form the image.

Question 8

What is Spatial Resolution?

Answer 8

Discernable separation of closely adjacent image details.

• Determined by the number and size of the pixels.
• Increasing Pixels Increases quality.

Question 9

What is Line Pair?

Answer 9

Greatest number of paired lines visible in 1mm of image.

-Increasing resolution increases sharpness.

Question 10

What is a Sensor?

Answer 10

Special plate sensitive to x-rays that captures the radiographic image )latent image in the film)

Question 11

Analog Film

Answer 11

Radiographic image produced by conventional film.

-Depicted by a continuous spectrum of gray shades between the extremes of white and black.

Question 12

Bit-depth Image

Answer 12

Number of possible Gray-scale combinations for each pixel.

Question 13

Charge-Coupled Device(CCD)

Answer 13

Solid-state silicone ship detector that converts light or x-ray photons into an electrical charge or signal; in digital imaging the CCD is found in the sensor.

Question 14

Digitize

Answer 14

In digital imaging, to convert an image into a digital form that, in turn, can be processed by a computer.

Question 15

Storage Phosphor Imaging

Answer 15

Method of obtaining a digital image in which the image is recorded on a phosphor-coated plate and then placed into an electronic processor, where a laser scans the plate and produces the image on a computer monitor.

Question 16

Gray scale

Answer 16

Very much like contrast in an image

It is defined as the number of shades of gray in an image.

Question 17

How many shades of gray does digital claim?

Answer 17

65,500 Gray Levels

Question 18

How many shades of gray can the monitor display?

Answer 18

Only 256 Gray levels

Question 19

0-255 Gray shades

Answer 19

0 being pure black and 255 being white.

Question 20

How many shades of gray can the human eye distinguish?

Answer 20

32 Shades of Gray

Question 21

X-ray Machine

Answer 21

must be equipped with timers capable of being set low enough for digital—Can still be used for traditional film radiographs by resetting the time exposure.

Question 22

What is best for the x-ray machine to be capable of?

Answer 22

low kV (70 or less) and low mA (5 mA or less) and have DC current

Question 23

Sensor

Answer 23

Wired or wireless
–Wired—connected to the computer via fiber optic cable that may be from 8-35 feet in length
–Wireless—use of a radiofrequency to communicate with the computer
Sensors come in sizes comparable to film and in 3 most common types

Question 24

What are the 3 types of sensors?

Answer 24

1. CCD- Charge Coupled Device
2. CMOS- Complementary Metal Oxide Semiconductor
3. PSP- Photo Stimuable Phosphor

Question 25

CCD- Charge-Coupled Device

Answer 25

• Most widely used
• also used in video cameras, fax machines, telescopes, etc.
• solid state detector made up of grids of transistor elements that convert x-rays to electrons.

Question 26

CMOS- Complementary metal oxide semiconductor

Answer 26

• solid state circuitry
• pixels can be smaller and chips more durable and less expensive
• require less computer power, so can connect via USB
• -Does not require an internal computer circuit card as does CCD needs
• Schick Technologies and the Kodak RVG 6000

Question 27

PSP- Photo Stimuable Phosphor

Answer 27

• completely different kind of sensor
• rare earth phosphor (barium europium fluoro-halide) coated plates used as sensors
• when exposed, PSP stores x-ray energy until stimulated by a laser
• a separate scanning device is required that “reads” the fluorescent signal and converts it into a digital image
• very similar to film in that multiple images are taken and the sensor plates “developed” by putting through scanner
• plates are reusable by erasing the image by exposing it to bright light

Question 28

Digital Software allows for what?

Answer 28

Manipulation of the image by the operator

Question 29

Digital Software Manipulation

Answer 29

1. Side-by-Side displays-May view multiple images
2. Magnification—up to 4x larger image
3. Density Contrast—May alter but only if an acceptable image is present to begin with.(Cannot alter too light an image to acceptable
4. Measurement Tools—”software rulers” can be used for lengths of root, bone loss, cyst size, etc.
5. Charting– made easier, can place notes, arrows, circles, etc
6. Digital Subtraction—merges two images and shows differences
7. Colorization

Question 30

What are the Advantages of Digital?

Answer 30

1. Less Radiation—50-80% less per film since sensors are more sensitive than film
2. Quicker viewing on the monitor
3. Eliminates darkroom and costs of it
4. Diagnostic image may be manipulated for interpretation—LEGAL IMPLICATION- IT IS FRAUD TO MANIPULATE IN THE FAVOR OF THE DENTIST IN A LAWSUIT
5. Improved gray scale
6. Remote transfer for consultation (e-mail)
7. Use in patient education via monitor

Question 31

Disadvantages of Digital

Answer 31

1. Expensive-Initial Investment Cost Greater
2. Technology Concerns
   - How long until out-dated
   - If computer crashes, malfuntions, virus, etc
   - Storage and back-up more complicated and should not delete old radiographs
   - System compatibility when transferring later
   - ID theft
3. Learning Curve
   1. There is a difference in reading digital vs. traditional images
   2. multiple mouse clicks are required to view a full mouth series or to compare
4. Sensor Size
   1. Sensors are thicker
   2. Patients complain more due to size
   3. More exposure needed to cover same area than in traditional
5. Infection Control
   1. sensors cannot withstand heat sterilization
   2. Plastic sheaths tear and leak
   3. keyboard has to be touched
6. Legal Issues
   1. May be altered
   2. Computer hackers

Question 32

What is DICOM?

Answer 32

Digital Imaging and Communications in Medicine is addressing the ID Theft. This will be ever Changing.