# Digitital

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1. what is film density?
the blackening of film
2. what is contrast?
3. what is film speed?
the amount of density a film produces for a given amount of exposure.. it takes less exposure to produce a given density with a faster film.
4. what is exposures latitude?
the range of exposures that produce densities in the diagnostic range.

-- as slope of the straight line portion increases, contrast increases, but exposure latitude decreases or becomes more narrow.
5. if the characteristic curve for 2 films were plotted on the same curve.. which would be the faster curve?
the curve located the farthest to the left is the fastest film
6. what are the film/ screen limitations?
• Density-- overexposed=to dark ; underexposed=to light
• contrast resolution-- atomic number of tissue must be greater than 10% in order to see
• fixed display--the display of a film on a view box is fixed.. in order to change must repeat
• archival requirements--manual handling for archival and retrieval.. lg storage needs
7. the signal is in analog form and must be converted to a digital form. what must convert it?
8. What point is the image in analog or digital form?
• Analog form-electons on detectors
• Digital- after it is has been converted by an ADC
9. What is the binary system? and know how to convert it.
Data processing done by the computer software.

• 1011
• 1 x 2^0=1
• 1 x 2^1=2
• 0 x 2^3=0
• 1x 2^4=16

=19
10. When digital images must be first converted to an analog image before it can be displayed on a monitor. what accomplishes this?
digital to analog converter (DAC)
11. what form is an image that is displayed on a monitor? analog or digital?
analog
12. What components make up CR?
• -photostimulable phosphor storage imaging plates
13. how does CR compare to film screen when talking about spatial resolution and contrast resolution?
CR has lower spatial resolution and higher contrast resolution
14. What components are necessary for DR?
• Digital x-ray machine (new)
• flat panel detector
15. When comparing DR to CR which offers the highest spatial resolution? and between that and film screen what has the highest of them all.
DR offers higher spatial resolution than CR. and film screen has the highest spatial resolution.
16. between CR, DR, and film/screen what has the widest exposure latitude?
CR and DR have the widest
17. when you over or under exposure digital what does the radiograph look like?
the radiograph looks normal under and over exposures do not effect DR
18. what is IMACS?
• image management and communication systems.. AKA PACS
• - it is in charge of sending the image from the acquisition modality to the monitor for display and diagnosis
19. what is QA/QC and what is special about it?
• activities are designed to ensure patient dose is as low as reasonable achievable to ensure good quality and reduce cost
• -- VERY MFG SPECIFIC IN DIGITAL

film screen - all machines do the same steps to check machine and processor, but when dealing with digital it is VERY MFG specific to how to check the machine and processor!!
20. What are some Input devices:
What are some Output devices:
Input: keyboard, mice, microphones, bar code readers, touch screens, image scanners

Output: Monitors, printers, speakers
21. What is Binary code?
when a computer takes data from the user and processes it using a machine language of 1s and 0s known as binary code
22. if the transistor circuit is closed and current passes through it is assigned what value number? and if the circuit is open and current does not pass through, it is assigned a value of what?
1, 0
23. What are the 2 major functions of the box are?
• - to hold all of the components in a relatively cool, clean and safe environment
• - to shield the outside environment from the radio frequencies being emitted by the electronic components of the computer
24. What is the brain of the computer and what does it do?
the CPU aka microprocessor.. small chip found on the motherboard.. and its main job is to read date from storage, manipulate the date and move the data back to storage or send it to external devices
25. What does the BIOS do?
• it is a basic input/ and output system
• - runs the startup diagnostic system
• - makes sure all the peripherals are functioning properly
• - oversees the basic function of receiving and interpreting signals
• - acts as the intermediary between the operating system and hardware
26. What is the Bus?
it is a series of connections, controllers, and chips that create information highways of the computer
27. What is temporary memory AKA ? and what is memory measured in?
RAM. memory is measured in bytes
28. What does CMOS use to retain information about the PC's hardware while the computer is turned off?
small rechargeable or lithium battery
29. What does a sound card do? and what does it interpret?
it contains all of the circuitry for recording and reproducing sound on the PC.. it interprets many different files types such as the WAV files.. MP3 files and MIDI files
 Author: Anonymous ID: 23139 Card Set: Digitital Updated: 2010-06-11 22:19:37 Tags: Test Folders: Description: digital test 1 Show Answers: