Intro to CR/DR and PACS Flashcards
CR
computed radiography system
DR
digital radiography
DF
digital fluoroscopy
NM
nuclear medicine
MRI
magnetic resonance imaging
CT
computed tomography
DSA
digital subtraction angiography
how do computers process numbers
on a binary base 0/1
what do modern computers correspond to
off/ on of trillions electronic switches : transistors
what is a bit
a binary digit ( base 2)
what is an analogue image
an image viewed on film/tv as an image composed of CONTINUOUS variations of optical density (not separate clumps)
what is a digital image
- analogue image converted to digital image via ADC
- matrix of binary numbers held in computer
- these numbers distinct from one another to determine shade of grey
ADC
analogue to digital conversion
what is sampling in ADC
conversion of analogue signal into digital signal via process of regular periodic measurement
what do more pixels mean
smaller - pixel size determines smallest structure that can be demonstrated in an image
- the more pixels the better the resolution
what does ADC determine
the digital values allocated to each pixel
what is a photo diode
very fast switch activated by light
what are flat panel detectors
they are an absorbing layer that converts x-rays into light
what converts light into electrical signals
amorphous selenium
difference between analog and digital image
- analog is various levels of brightness and colours and not broken down into individual pieces
- digital images are recorded as many binary numbers and divided into matrix of small pixels
what is teleradiology
- images transferred via telephone line
- digital images transmitted to different location
- images received with image manipulation
advantages of teleradiology
- hospital to home emergency reporting - efficient
- remote locations linked to larger hospital
disadvantages of teleradiology
- doctors not discussing ur medical findings with you face to face leads to miscommunication
what does matrix size determine (number of pixels)
determines spatial resolution
what does matrix depth (number of bits) determine
contrast resolution
pre-processing
automatically manipulates data to optimise display of image and reduces need for post processing
post-processing
pre-processed image is displayed for review
- area under investigation
-patient positioning and collimation are checked
examples of post processing
- addition of anatomical markers
- image annotation
- window and level adjustment
- electronic collimation
- magnification
advantages of digital imaging
- wide latitude
- improved image contrast
- adjusts for over and under exposure
- eliminates repeats
- digital archiving
- radiographs comparable
