The amount of density a film produces for a given amount of exposure.
True or False: It takes less exposure to produce a given density with a faster film.
The range of exposures that produces densities in the diagnostic range.
If the characteristic curve for two films were plotted on the same graph, which one would be faster?
The one farthest to the left would represent the faster film.
Film screen limitation for density.
An overexposed film appears much too dark. An underexposed film appears much too light.
Film screen limitation for contrast resolution.
The contrast resolution number of film is 10. That means that there must be at least a 10% difference in tissue before it will be detected on the radiograph as different shades of gray.
Film screen limitation for fixed display.
The display of a film on a view box is fixed, in order to change it the image must be repeated.
Film screen limitation for archival requirements.
Manual handling for archival and retrieval. This requires a large storage unit.
How does an analog signal become converted into a digital signal?
Analog to digital converter (ADC)
What point is the image in analog and digital form?
Analog -- electrons on detectors.
Digital -- After it has been converted by an ADC
Convert binary language: 1011
1 x 20 = 1
1 x 21 = 2
0 x 23 = 0
1 x 24 = 16
A digital image must first be converted to an analog image before it can be displayed on the monitor. How does this happen?
This is accomplished by the digital to analog converter (DAC)
When an image is displayed on a monitor, is it analog or digital?
What components make up CR?
Traditional x-ray machines.
Photostimulable phosphor storage imaging plates.
When comparing CR to film/screen imaging, CR has ______ spatial resolution, but _______ contrast resolution.
What components make up DR?
Digital x-ray machine.
Flat panel detector.
When comparing DR to CR, which ofters higher spatial resolution?
*Film/Screen has the highest of all.
When comparing CR, DR, and film/screen, which has the widest exposure latitude?
CD and DR
True or False: Under and over exposure to a radiograph no longer produces an image that is too dark or too light when working with digital?
True. Under and over exposures do not effect DR.
What is IMACS?
Image Management and Communication Systems. A.K.A PACS.
What is PACS responsible for?
It is the system responsible for sending the image from the acquisition modality to the monitor for display and diagnosis.
What is QA/QC?
QA/QC activities are designed to ensure patient dose is as low as reasonably achievable, ensure optimal image quality, and reduce operating cost. Test are very manufacturer specific.
Keyboard, mice, microphone, touch screens.
Monitors, printers, speakers.
Computer takes data from the user and processes it using a machine language of 1s and 0s.
If the trasistor circuit is closed and current passes through, it is assigned a value of _______.
IF the circuit is open and current does not pass through, it is assigned a calue of ______.
The box has two main functions....
To hold all of the components in a relatively cool, clean, and safe enviroment.
To shield the outside environment from the radio frequencies being emitted by the electronic components of the computer.
True of False: The box is the brain of the computer?
False. The CPU is the brain of the computer.
What is the basic input/output system?
BIOS. BIOS runs the start-up diagnostics on the system.
A series of connections, controllers, and chips that creates the information highway of the computer.
Memory is measured in....
What does CMOS use to retain information about the PC's hardware while the computer is turned off?
A small rechargeable or lithium battery.
What does a sound card interpret?
WAV files, MP3 files, and MIDI files
Enables the PC to connect to other PCs that are on the same network.
If the computer ever receives a power surge, what is designed to take the brunt of the force?
The power supply.
Compare DVD storage to CD storage.
A DVD holds up to 7 times more data than the CD.
What are the 3 main types of CD/DVD drives?
ROM - (Read only memory)
R - (Write once, read many)
RW - (Read and write many times)
What is a Land and Pit?
Land - 1 - Reflects
Pit - 0 - Does not reflect
What are the 2 basic types of keyboards?
Soft -- no sound
Click -- sound
An individual controllable set of dot triads.
The measurement of how close the dots are located to one another within a pixel.
True or False: The smaller the dot pitch of a display, the finer the resolution.
A measure of how fast the monitor rewrites the screen or the number of times that the image is redrawn on the display each second.
How does refresh rate relate to flicker?
Refresh rate helps control the flicker as seen by the user, the higher the refresh rate the less flicker seen.
How does CRT create the image?
Consists of a cathode and anode within a vacuum tube. Cathode boils off a cloud of electrons, and then a potential difference is placed on the tube. A stream of electrons is sent across to the anode, which is the case of the monitor is a sheet of glass coated with a phosphor layer. Electrons then strike the phosphor on the glass, causing glass to emit a color based intensity where most electrons strike. .. does this all in a raster scan pattern
How does LCD emit an image?
LCD produces images by shining or reflecting light through a layer of liquid crystal and a series of color filters. When a current is applied to the liquid crystal, it aligns and allows light in varying intensities through to the next layer of glass through color filters. Light forms the colors and images seen on display.
How does plasma screens emit an image?
They are made up of many small fluorescent lights that are illuminated to form the color of the image.
Compare CRT and LCD.
CRT -- least expensive, bulky, more luminance than LCD.
LCD -- More expensive, less of viewing angle, takes up less space.
What are the 3 major operating systems?
Windows by Microsoft
UNIX / Linux
What TYPE of operating system does modern x-ray equipment use?
Two or more objects sharing resources and information.
Compare LAN and WAN
LAN -- local area nonnection. Least expensive.
WAN -- wide area network. Connects computers that are not physically attached.
What are the two typical classifications of networks?
Peer-to-peer -- Each computer on the network is considered equal.
Server based -- Centralized computer controls the operations, files, and sometimes the programs of the computer.
Client based -- Server returns only the results back to the client.
A computer that manages resources for other computers, servers, and networked devices.
A component found on a network that request services and resources from a server.
Computer that can work independently from the network.
Similar to TV cable. Center conduction wire surrounded by insulation and grounded shield and braided wire.
Wire similar to telephone wire. Used for LAN.
Uses glass threads to transmit data on a network -- easy to damage.
Uses infared or radio frequencies. No cable needed.
Provides the interface between the computer and the network medium.
Network Interface Card
Device for connecting several pieces of equipment.
Sends data only to those devices to which the data is directed.
Physical (wired) connection from one network segment to another.
Directs messages to intended target even it target is on a separate network and uses a different network protocol.
Address is made up of four octets of numbers. First set indicates the network class.
True of False: Network protocols send data from one device to another.
Needed to understand the basic principles of network communication
OSI Model. Open Systems Interconnection Model.
A network in which all devices are physically attached to and listen for communication on one single wire.
Devices are connected in a circle.
Connected to a central hub or switch. Most Common
Multiple passageways. What internet uses.
A device or system that represents changing values as continuously variable physical quantities.
Only can display information in few discrete values.
Numbers that represent shades of gray on a X and Y axis.
Spatial Location Domain
A mathematical algorithm that is used to change image data from the spatial location domain to the spatial frequency domain.
The Fouier Transformation
Change the image so that is meets the needs of the viewer, usually it facilitates the diagnosis made by the radiologist.
Improves the quality of images that have been degraded.
Allows for measurements and statistics as well as image segmentation.
Reduces the size of the image dile which will then reduce trasder time and storage needs.
Each box within the matrix is called a _______.
A digital image is made up of a 2D array of nubmers called a _________.
Each pixel represents a 3D volume of tissue known as a _______.
As pixel size decreases, spatial resolution _________.
As matrix size increases, with field of view remaining the same, pixel size ___________. Therefore spatial resolution ___________.
As bit depth increases, more shades of gray are able to be represented and thus, contrast resolution __________.
What are the 3 steps in digitizing an image? How does a ADC fit into these steps?
1) Scanning -- scans in a raster pattern.
3) Quantization -- An ADC assigns a number to each pixel which is representative of a gray value.
A graph of the shades of gray of an image versus the number of pixels containing each shade of gray.
A mapping function in which all pixels are changed to a new gray value, a method of adjusting image contrast and brightness.
Look Up Table (LUT)
The range of the pixel values (shades of gray).
The center of the range.
Window width controls....
Window level controls...
As window level increases , brightness _________.
The output image pixel value is calculated using a small area of pixels surrounding the input pixel.
Local Processing Operations
Spatial frequency filtering in the spatial location domain is an example of a local processing operation.
Use all the pixels in the input image to calulate the gray level for one pixel in the output image.
Give an example of global processign operations.
Spatial Frequency Filtering
What is used to chagne the data into the frequency domain.
The Fourier Transformation.
Allows the user to change the position or orientation of pixels.
A company provides outsourcing of archiving and management functions to the hospital for a pay per use, or pay per month charge.
Application Service Provider
Modalities that use a scanner to acquire the image data at full spatial resolution and grayscale
Digitize the analog signal obtained form the image receptor.
The data transfer rate of the network.
Individual device connected via the network.
Connection between nodes.
What is the slowest link? What is the fastest link?
Telephone modem -- slowest
Fiber optics -- fastest
Ensures access only to those people for whom the information is intended.
Allows the message recipient to verify the identity of the sender and the sender to verify the identity of the recipient.
Ensures that the information received has not been altered deliberately or accidentally.
Consist of a jukebox containing several magnetic or optical disks that are controlled by a robotic arm.
Short term storage
Digital Linear tape (DLT) is often used for?
Long term storage
Short term and long term storage components can be connected by a sub network called?
Storage Area Network (SAN)
Storage that cannot be removed and provides immediate access to images (RAM).
Storage is removable and has longer retrieval times (RAID)
Storage devices that must be retrieved by a person and loaded onto a drive. This is the cheapest form of storage with the largest storage capacity.
What is the purpose of image compression?
To reduce file size, which reduces the storage requirements and transmission time
True of False: Because a radiologist is reading an image for primary diagnosis, only images with lossless compression are used.
The ratio of the storage capacity required for the original image compared to the storage capacity required for the compressed file.
More pixels are displayed in the vertical direction than in the horizontal direction.
More pixels are displayed in the horizontal direction than in the vertical direction.
What is the desirable image display time?
PACS is an image based system with _______ as a standard.
RIS is a text based system with ______ as a standard.
Allows users to remotely access images using internet browser technology.
How does the number of steps in workflow for film/screen compare to digital?
Fewer steps in digital
Current set of standards that allows different modalities within radiology to communicate with each other. Current set of standards.
What is a DICOM conformance statement?
A statement that describes the capabilities of a device.
What is the purpose of UIDs?
To globally identify each image set.
Standard for text based systems with health care so that communication between network conponents is possible.
What is the purpose of inegration health enterprise (IHE)?
To facilitate communication between DICOM and HL7.
What are the FDA regulations for PACS?
Require manufacturers to submit a pre market approval and registration of both the product and facility.
Deals with the use and disclosure of protected health information.
Used to send and recieve signals from computers.
Converting a digital signal from the computer into an analog signal that can be sent over a communication link.
Analog converted to digital.
Changing data into information.
This is replacing traditional paper based health records.
Electronic Health Record (EHR)
A database that contains patient demographic information and assists in identifying and locating patient records.