Limitations of film-based imaging - ANSWER Been around since 1895 Used
in all radiology modalities. The patient is exposed to a predetermined amount of
radiation that is needed to provide a diagnostic image. If an image is under/over
penetrated the patient would have to be exposed again, increasing the dose. Not
an ideal way to perform radiation detection, image display and image archiving.
Film-screen(x-ray) can't show differences in tissue contrast less than
10%(contrast resolution). Optical range and contrast for the film are fixed and
limited(can't window/level them, have to retake). Stored-in envelopes require
manual handling for archiving and retrieval.
Major components of generic digital imaging system - ANSWER Data
acquisition, Image processing, Display/storage/archivingImage communication
Data acquisition - ANSWER 1st step- systematic method of collecting data
from the patient, Attenuation data collected for imaging modality, Ct- x-Ray
tube and digital image detectors do this, Output signal is an electrical
signal(analog signal that varies continuously on time), Analog, signal must be
converted into a digital signal for, computer processing using an ADC converter
Image processing - ANSWER Performed by digital computer , Takes input
digital image, processes it to produce output digital image(using binary number
system), ADC sends digital data for digital image processing by a digital
computer, Accomplished by set of operations, techniques to the input image
into an output image, these operations can reduce noise, enhance sharpness, or
change the contrast
Image display, storage, and communication - ANSWER Output digital image
must be converted into an analog signal before it can be displayed on the
monitor using a DAC, Can be archived on magnetic data carriers and laser
optical disks for retrospective viewing and manipulation, Can be communicated
electronically through computer networks to remote sites
, Image formations and representation analog images - ANSWER Analog
images are continuous images, Images formed when x-rays pass through patient
and projected onto x-Ray film, Films processed in chemical solutions to render
visible. These images formed by photochemical process, Images can be formed
by photo electronic means, images may be represented as electrical(analog)
signals that emerge from photo electrical device
Image formation and representation digital images - ANSWER Numerical
representations or images of objects, Formation of any digital image requires
digital computer, Any information that enters the computer must be converted
into digital form(numbers). ADC converts continuous signals to discrete
signals(digital data). Computer receives data and then does necessary
processing. Result=digital and can be displayed as digital image, Output=analog
image
Digital image processing - ANSWER In image processing it's necessary to
convert an input image into an output image, if both are analog this is referred
to as analog processing, if both are discrete this is referred to as digital
processing, When an analog image must be converted into digital data for
computer input a digitizations system is required , CT is based on a
reconstruction process whereby digital image, changed into a visible physical
image, process-"a series of actions or operations leading to a desired result;
thus, a series of actions or operations are performed upon an object to alter its
form in a desired manner".
Spatial location domains=CT - ANSWER Used in radiography and CT, The
digital image is a numerical image arranged in such a manner thAt the location
of each number in the image can be identified using the x-y coordinate system,
x=columns(horizontal), y=rows(vertical), The first pixel in the upper left hand
corner is always identified as 0,0
Spatial frequency domains - ANSWER Used in MRI, frequency refers to the
number of cycles per unit length(the number of times the signal changes per
unit length).
Image domains - ANSWER Digital image processing can transform one image
domain into another image domain, An image in the spatial location can be
transformed into a spatial frequency domain image, The Fourier transform(FT)
in all radiology modalities. The patient is exposed to a predetermined amount of
radiation that is needed to provide a diagnostic image. If an image is under/over
penetrated the patient would have to be exposed again, increasing the dose. Not
an ideal way to perform radiation detection, image display and image archiving.
Film-screen(x-ray) can't show differences in tissue contrast less than
10%(contrast resolution). Optical range and contrast for the film are fixed and
limited(can't window/level them, have to retake). Stored-in envelopes require
manual handling for archiving and retrieval.
Major components of generic digital imaging system - ANSWER Data
acquisition, Image processing, Display/storage/archivingImage communication
Data acquisition - ANSWER 1st step- systematic method of collecting data
from the patient, Attenuation data collected for imaging modality, Ct- x-Ray
tube and digital image detectors do this, Output signal is an electrical
signal(analog signal that varies continuously on time), Analog, signal must be
converted into a digital signal for, computer processing using an ADC converter
Image processing - ANSWER Performed by digital computer , Takes input
digital image, processes it to produce output digital image(using binary number
system), ADC sends digital data for digital image processing by a digital
computer, Accomplished by set of operations, techniques to the input image
into an output image, these operations can reduce noise, enhance sharpness, or
change the contrast
Image display, storage, and communication - ANSWER Output digital image
must be converted into an analog signal before it can be displayed on the
monitor using a DAC, Can be archived on magnetic data carriers and laser
optical disks for retrospective viewing and manipulation, Can be communicated
electronically through computer networks to remote sites
, Image formations and representation analog images - ANSWER Analog
images are continuous images, Images formed when x-rays pass through patient
and projected onto x-Ray film, Films processed in chemical solutions to render
visible. These images formed by photochemical process, Images can be formed
by photo electronic means, images may be represented as electrical(analog)
signals that emerge from photo electrical device
Image formation and representation digital images - ANSWER Numerical
representations or images of objects, Formation of any digital image requires
digital computer, Any information that enters the computer must be converted
into digital form(numbers). ADC converts continuous signals to discrete
signals(digital data). Computer receives data and then does necessary
processing. Result=digital and can be displayed as digital image, Output=analog
image
Digital image processing - ANSWER In image processing it's necessary to
convert an input image into an output image, if both are analog this is referred
to as analog processing, if both are discrete this is referred to as digital
processing, When an analog image must be converted into digital data for
computer input a digitizations system is required , CT is based on a
reconstruction process whereby digital image, changed into a visible physical
image, process-"a series of actions or operations leading to a desired result;
thus, a series of actions or operations are performed upon an object to alter its
form in a desired manner".
Spatial location domains=CT - ANSWER Used in radiography and CT, The
digital image is a numerical image arranged in such a manner thAt the location
of each number in the image can be identified using the x-y coordinate system,
x=columns(horizontal), y=rows(vertical), The first pixel in the upper left hand
corner is always identified as 0,0
Spatial frequency domains - ANSWER Used in MRI, frequency refers to the
number of cycles per unit length(the number of times the signal changes per
unit length).
Image domains - ANSWER Digital image processing can transform one image
domain into another image domain, An image in the spatial location can be
transformed into a spatial frequency domain image, The Fourier transform(FT)
