digital radiography: best practices

Question 1

when were Digital radiographs first invented

Answer 1

in the late 80’

Question 2

Characteristics of the first radiographs

Answer 2

V. large
TV not computer
no storage or manipulation of image
cost

Question 3

when did Digital x-rays become like today

Answer 3

In the 90s

Question 4

what is a digital image

Answer 4

A representaion of a 2d image as a finite set of digital values called pixels

Question 5

what do pixels represent

Answer 5

represent gray levels, colors, heights….

Question 6

is a digital scene actually the real image

Answer 6

No an approximation of a real scene

Question 7

Benifit of Digital X-ray to standard to patient

Answer 7

reduction compared to F-sped between 0-50 percent (lower dose)
Increase in number of radiographs made
INcrease in ease of remakes

Question 8

why do digital

Answer 8

Efficient work flow
Image enhancement
Better case acceptance
Co-diagnosis

Question 9

Digital Imaging chain

Answer 9

Image acquisition
Image processing
Image display

Question 10

retake rate of digital vs. Film

Answer 10

digital: 20%
FILM: 9%

Question 11

what is involved in image Acuisition

Answer 11

X-ray tube
Sensor
sensory placement and exposure

Question 12

How should the X-ray tube act for digital X-rays

Answer 12

timer capable of making reproducible short exposures if image quality is suoptimal (may need to upgrade)

Question 13

systems for making digital X-rays

Answer 13

CCD
CMOS
Phosphors

Question 14

what type of digital x-rays are indirect

Answer 14

Phosphors (scanning)

Question 15

How does CCD digital X ray work

Answer 15

• X-ray hits sensor and produces electrons at the same rate of the x-ray hitting
• One well transfers the electrons to the next
• edge of the CCD provides Electrical signal

Question 16

How does a CMOS work

Answer 16

each pixel has its own transistor and this is read directly

Question 17

what happens if too many electrons in a well

Answer 17

spill over and muddy image (over exposure)

Question 18

which type of sensor has more noise

Answer 18

The CMOS due to the extra transistors

Question 19

what is a Wireless sensor mades of (PSP)

Answer 19

plastic plate coated with phosphor material sensitive to X-rays

Question 20

what is a PSP

Answer 20

the plate of a wireless sensor (photostimulable phosphor plate)

Question 21

how does a PSP work

Answer 21

• Sensor exposed to an x-ray which creates a latent image stored on the plate
• then image digitalized with scanner

Question 22

what must be done to a PSP after an image is taken

Answer 22

cleared by light exposure for several minutes before next use

Question 23

steps of a PSP

Answer 23

Exposure
Stimulate with laser
reading due to light emision
Ease with light

Question 24

what is the weakest part of the sensor

Answer 24

the junction to the computer

Question 25

what are extraoral digital radigraphs

Answer 25

PAnoramic | Cephalometric

Question 26

do most current X-ray detectors work well

Answer 26

GEnerally yes, interms of spatial and contrast resoltuions and in terms of exposure latitude - indepent of modality applied`

Question 27

Characteristics of digital detector characteristics

Answer 27

Contrast REsolution Spatial rsolution Detector Latitude Detector sensitivity

Question 28

what is contrast resolution

Answer 28

Dynamic range (ability to distriguish different densities in the image

Question 29

what affefcts contrast resolution

Answer 29

Attenuation of radiation by tissues Capacity of receptor computer display ability of observer

Question 30

what does bit mean

Answer 30

it is the power 2 is raised to to determine the amount of gray levels are capable of being made

Question 31

what is spatial resolution

Answer 31

the capacity to distinuish fine detal

Question 32

smallest picel size

Answer 32

20 microns (24 lp/mm)

Question 33

HUman eye can differentiate how many lp/mm without maginification

Answer 33

6-8 (less than the smallest pixel)

Question 34

what is detector latitude

Answer 34

Ability of receptor to capture a range of exposure

Question 35

what is detector sensitivity

Answer 35

Ability to respond to small amouts of radiation

Question 36

standard for detector sensitivity

Answer 36

No classification yet

Question 37

what is Detector quantum effeciency

Answer 37

Is the measure of noise and contrast expressed as a function of object detail

Question 38

what does a DQE of 100% mean

Answer 38

A perfect detector, meaning all info that reaches detector is trasferred out of detector

Question 39

what are qualities of sensors

Answer 39

Spatial resolution Bit depth Active area

Question 40

what should the bit depth be at least for a senosr

Answer 40

at least 12

Question 41

important things to think about when it comes to sensory

Answer 41

``` Sensory reliablility (life span) Software integration with practice management software ```

Question 42

Roll of image processing

Answer 42

To restore, enhance, or analyze image

Question 43

aspects of image enhancement

Answer 43

Brightness and contrast Sharpening and smoothing color Digital subtraction

Question 44

what does a histogram do

Answer 44

Shows certain spectrums of color

Question 45

what are kinds of analysis tools

Answer 45

Zoom Measurement Digital subtraction

Question 46

what is digital subtraction

Answer 46

- when 2 radiographs are taken with the same exposure geometry over a time interval - images superimposed - computer compares and removes whatever is exactly the same giving a clear image of anything that is different

Question 47

how do changes look in digital subtraction

Answer 47

displayed as a resultant image against a neurtral gray background

Question 48

how much bone mass can digital subtraction notice

Answer 48

A change as little as 5%

Question 49

how many practicing dentist have experience problems with digital radiography

Answer 49

about 65%

Question 50

what is one of the weaker links in the technical chain of digital radiograph

Answer 50

Monitor

Question 51

room lighting affect on analysis of radiographs

Answer 51

Affects the diagnosistic outcome of low contrast patterns (low light good)

Question 52

affect of high luminance

Answer 52

results in better image quality, making subtle lesions easier to detect

Question 53

Luminance of different things

Answer 53

``` Viewboxes (1000-2000 Cd/ Msequared reg monitors (250-300 medical monitors (1000) ```

Question 54

What is luminence

Answer 54

MAx and Min amount of light emitted from display monitor (contrast ratio)

Question 55

what kind of devices have small picture elemets

Answer 55

High quality photographic and medical display devices

Question 56

how much does contrast ratio drop at a vewing angle of 85 degrees

Answer 56

10:1

Question 57

shades of gray in a medical display

Answer 57

4096(12 bit) | - consumer display is 8 bit

Question 58

important things for image storange

Answer 58

Prevention of permanent deletion or modification | Backup considerations

Question 59

Size of aradiograph

Answer 59

200 kb to 6MB

Question 60

what is the standard for for didigtal communcation

Answer 60

Digital imaging and Communication in mediicine stand (DICOM)

Question 61

benifit of Following DICOM

Answer 61

makes sharing images simpler between providers

Question 62

where should you test new X-ray machines and why

Answer 62

In your own office so images can be standaradizes and not preselected also know how to integrate and environement

Question 63

how long do X-ray ray equipment work

Answer 63

5-7 years

Question 64

cost of CCD and CMOS

Answer 64

5-8k

Question 65

cost of PSP plates

Answer 65

30-50

Question 66

how much ram should you have

Answer 66

4 gigabytes

Question 67

CPU speed

Answer 67

2 gigahertz

Question 68

Storage in server

Answer 68

Terabyte | dedicated server need a hardrive of 500GB

Question 69

USB?

Answer 69

Always good

Question 70

should you go wireless or nah

Answer 70

Sinve large files, wired is faster and secure