display/ QA Flashcards
what does cathode ray tube (CRT) contain?
- a phosphor-coated florescent screen
- electron beam generator
how does a Cathode ray tube work?
- electorns which strike the inside of the screen will cause the pixels at that spot to temporarily light up
CRT- the brighness of the dot on the screen = ?
strength of the electron beam
The CRT will generate electron beams that will ‘sweep’ the inner surface of the screen and cause lines to appear on the screen. This is called?
raster scanning
raster scanning involves how many horizontal lines?
525 horizontal lines
- grouped into odd and even fields (262.5 line/field)
what is twin interlacing?
In a given moment, one field is constructed; in the next moment, the other is constructed
in raster scanning how many images/second?
30 images/second
what is refresh rate?
how many images are shown on the screen per second
what is frame rate?
how quickly frames are built
- number of images entered into the image memory per second
refresh rate limits?
frame rate
instruments- display?
Frame rate Image Memory Refresh rate
colour display involves?
- 3 cathode ray tubes
- 1 per colour
flat panel display (LCD)?
- Liquid panel display
- matrix of photo-electric elements
Amplitude of voltage will decide?
luminance (brightness of element)
refresh rate on a typical LCD?
60 Hz
LCD advantages over CRT?
- display is much lighter and thinner
- good image quality, brighter image
- reduced eyestrain
- perform well in range of ambient light environments
- lower power consumptions and energy emissions
flat panel display (plasma)?
- electrical charge ionizes gas producing UV light
- UV light hits a phosphor coated screen which will glow
- 85Hz
flat panel display (organic LED)?
- latest and greatest, even thinner
- involves light emitting diode
Information received at the display can be shown in many different ways (3)?
- B-mode
- M-mode
- A-mode
brightness mode AKA?
- greyscale
- 2D
- suggests the brightness of each reflector at each anatomical position
M-mode?
- motion mode
- cardiac structures
- displays info from a single scan line- beam is stationary
- amplitude at each depth represents brightness of reflector
M-mode Y and X axis?
y-axis: depth
x-axis: time
in M-mode stationary areas show as?
straight lines
- moving areas show as wiggly lines
what is A-mode?
- amplitude mode
- displays info from a single scan line- beam is stationary
A-mode y and x axis?
y-axis: amplitude (brightness)
x-axis: depth
A-mode is mainly used in what kind of imaging?
opthalmic imaging
what is RAM?
- random access memory
- information storage
- temporary, very quick to access
- info lost when machine is turned off
‘image memory’ within the image processor uses?
RAM
ROM?
- rean only memory
- permanent info in storage
- will remain even if machine is turned off
Programmable ROM- PROM?
- permanent information in storage
- can still be accessed, adjusted, erased
- will remain even is machine is turned off
Where might the images we take and store fall under?
PROM
HIS – Hospital Information System?
An integrated information system designed to manage the administrative, financial and clinical aspects of a hospital
Everything involved in running a hospital (including paper and digital systems)
RIS – Radiology Information System?
- built to manage workflow in radiology
- Patient scheduling, intake, worklist generation, medical reporting, transcription, and report management
- a part of the HIS
PACS – Picture Archiving and Communication System
Storage, retrieval and distribution of images
2 main types of testing- quality assurance?
1- operational QA
- acoustic output
what is operational quality assurance?
- anatomical imaging/measurements
- doppler evaluation
what is acoustic output?
- beam former/transducer
- related to bioeffects
operational QA examples?
- tissue equivalent phantom
- test object
acoustic output?
hydrophone
what is TEP – tissue equivalent phantoms?
- AKA tissue mimicking phantom (TM)
- mimics soft tissue characteristics
- we scan along the top
TEP- tissue equivalent phantoms?
- graphite- filled aqueous gels
- urethane rubber
- nylon strings used to demarcate echogenic points
Graphite-filled aqueous gels?
1.54 mm/μs
urethane rubber?
1.45 mm/μs
TEP function?
- come with blue prints
- compare measurements on screen to blueprints
- check accuracy of axial and lateral resolution
TEP mimics?
- cysts
- solids
Hydrophone?
- aka microprobe
- Small transducer element on a long hollow needle (<1mm diameter)
- Point transducer at hydrophone, hydrophone picks up pressure wave, converts to a voltage
Polyvinylidene Fluoride Membrane (PVDF)
Point transducer at PVDF membrane, picks up pressure wave, converts to a voltage
Oscilloscope readings can be used to calculate?
T, PD, PRP, DF
f, λ, SPL
Spectrum analyzer?
connected to oscilloscope: able to break down incoming bandwidth to individual frequencies
oscilloscape readings can calculate?
amplitude based on peasks of the signal
Calorimeter
Measures tiny, tiny changes in temperature
Involves a sensitive thermometer
Relates the change in temperature to the output power/intensity
