Exam 1 - 7. Digital Imaging Flashcards
2
Digital imaging has ____ less radiation dose than film imaging.
6
1 Bit = ____
6
1 byte = ____ bits
6
What is the normal display for binary system?
6
What is the twelve bit sensory?
7
What is the smallest element of a digital picture?
7
Digital images are numeric. There are _____ of pixels and different shades of ____ in each pixel.
8
Pixels are arranged in rows and columns to form the _____.
9
Pixel values typically represent ____
9
Digitization implies that a digital image is an ____ of a real scene.
13
What are three things needed for image acquisition?
14
What is the direct digital image receptor?
14
What is the indirect digital image receptor?
16
Sensor is a laminate of _____ screen, ____ faceplate, and _____ layer.
16
Fiber optic faceplate protects _____ layer and provides _____.
17
The semiconductor layer is usually made up of _____.
17
With the semiconductor layer, electrons are attracted toward the most _____ potential in the device where they create _____.
17
Each charge packet corresponds to ______.
17
With the semiconductor layer, the amount of electron hole pairs is proportional to the amount of ____ an area receives.
18
Each pixel is like a tiny battery with its charge equal to the ______ trapped inside. The computer records the charge in each pixel and converts it to a _____.
20
Every digital image is “born” _____ to _____.
20
What is the term for “a small range of voltage values are grouped together as a single value?
20
What is the term for “Every sampled signal is assigned a numerical value”?
22
Charge-coupled device read in _____ fashion.
22
For complementary metal oxide semiconductors, each pixel is _____.
23
The emission by a substance of stored energy as light is referred to as _____.
23
Photostimulable phosphor playes (indirect digital imaging) consist of reusable imaging plates coated with ____ instead of the sensor
23
What is the main advantage of photostimulable phosphor plates?
24
The PSP plate is made of _______.
27
What is a pro of CCD/CMOS compared to PSP?
27
What are three pros to PSP compared to CCD/CMOS.
30
As exposure to x-ray photons increases, the degree of darkening _____, and so the density _____.
30
What are three factors affecting the radiographic density of an image?
31
What is the most important factor affecting radiographic density of an image?
31
Increasing the milliamperage (mA), peak kilovoltage (kVp), or exposure time increases the _____ reaching the film and
thus increases the ______.
31
For subject thickness, the thicker the subject, the more the beam is attenuated, and the ____ the resultant image.
31
The greater the density of a structure within the subject, the ____ the attenuation of the x-ray beam directed through the subject or area.
32
Dense objects (which are strong absorbers) cause the radiographic image to be light and are said to be _____.
32
Objects with low densities are weak absorbers. They allow most photons to pass through, and they cast a dark area o film that corresponds to the ______ object.
33
What is the term for the difference in density between areas on the radiograph?
33
Radiographic contrast depends on what three things?
34
What four things does subject contrast depend on?
34
What is the formula for subject contrast?
34
What is the relationship between kVp and subject contrast?
36
Resolution is not that important for detecting _____. ___ and ____- plays a much larger role.
39
What are three useful tools in digital image processing? What are two things that are sometimes useful?
40
What is the best means to alter the brightness or contrast of an image?
