Digital image processing-CT
Study online at https://quizlet.com/_142h86
1. Limitations of film Been around since 1895 Used in all radiology modalities. Patient is ex-
based imaging posed to predetermined amount of radiation that is needed to provide
a diagnostic image. If image is under/over penetrated the patient would
have to be exposed again, increasing dose. Not ideal way to perform ra-
diation detection, image display and image archiving. Film-screen(x-Ray)
can't show differences in tissue contrast less than 10%(contrast reso-
lution). Optical range and contrast for film are fixed and limited(can't
window/level them, have to retake). Stored in envelopes requires manual
handling for archiving and retrieval.
2. Major components of Data acquisition, Image processing, Display/storage/archivingImage
generic digital imaging communication
system
3. Data acquisition 1st step- systematic method of collecting data from the patient, Attenua-
tion 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
4. Image processing 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
1/7
, Digital image processing-CT
Study online at https://quizlet.com/_142h86
5. Image display, storage, Output digital image must be converted into an analog signal before it can
and communication be displayed on the monitor using a DAC, Can be archived on magnetic
data carriers and laser optical disks for retrospective viewing and manip-
ulation, Can be communicated electronically through computer networks
to remote sites
6. Image formations and Analog images are continuous images, Images formed when x-rays pass
representation analog through patient and projected onto x-Ray film, Films processed in chem-
images ical 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
7. Image formation and Numerical representations or images of objects, Formation of any digital
representation digital image requires digital computer, Any information that enters the comput-
images er must be converted into digital form(numbers). ADC converts continu-
ous 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
8. Digital image process- In image processing it's necessary to convert an input image into an
ing 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".
2/7
Study online at https://quizlet.com/_142h86
1. Limitations of film Been around since 1895 Used in all radiology modalities. Patient is ex-
based imaging posed to predetermined amount of radiation that is needed to provide
a diagnostic image. If image is under/over penetrated the patient would
have to be exposed again, increasing dose. Not ideal way to perform ra-
diation detection, image display and image archiving. Film-screen(x-Ray)
can't show differences in tissue contrast less than 10%(contrast reso-
lution). Optical range and contrast for film are fixed and limited(can't
window/level them, have to retake). Stored in envelopes requires manual
handling for archiving and retrieval.
2. Major components of Data acquisition, Image processing, Display/storage/archivingImage
generic digital imaging communication
system
3. Data acquisition 1st step- systematic method of collecting data from the patient, Attenua-
tion 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
4. Image processing 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
1/7
, Digital image processing-CT
Study online at https://quizlet.com/_142h86
5. Image display, storage, Output digital image must be converted into an analog signal before it can
and communication be displayed on the monitor using a DAC, Can be archived on magnetic
data carriers and laser optical disks for retrospective viewing and manip-
ulation, Can be communicated electronically through computer networks
to remote sites
6. Image formations and Analog images are continuous images, Images formed when x-rays pass
representation analog through patient and projected onto x-Ray film, Films processed in chem-
images ical 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
7. Image formation and Numerical representations or images of objects, Formation of any digital
representation digital image requires digital computer, Any information that enters the comput-
images er must be converted into digital form(numbers). ADC converts continu-
ous 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
8. Digital image process- In image processing it's necessary to convert an input image into an
ing 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".
2/7
