RT 201 sir dean Flashcards
*It is a numerical representation of the patients
that is a is a matrix of picture elements or
pixels.
*It can be described with respect to several
characteristics or fundamental parameters,
including the matrix, pixels, voxels, and the bit
depth
Digital image
*A square arrangement of numbers of columns and rows.
*It is the number of pixels along the length and width of an
image.
*Each box within the ______ corresponds to a specific
location in the image that pertain to a specific area of the
patient’s tissue.
*_____size is the number of pixels along the length and
width of the image.
Matrix
*It is the basic unit of a digital image.
* It is expressed in the x and y direction.
*It is considered as the basic building block of the
medical image.
*The size of the ______ is determined by the ratio of the
actual image and the size of the image matrix.
*Each ______ contains a specific value, the value
contained in each _____ represents the part of a
certain anatomy of the part being imaged
PIXEL (Picture Elements)
*It is a unit of graphic
information that defines a
point in the
three-dimensional space.
*Expressed in the x, y, and
z direction
*It represents the
information contained in
a volume of tissue in the
patient.
VOXELS (Volume Element)
*______ is the ability to image two separate objects
and visually distinguish one from the other.
Resolution
Two Categories of Resolution
*Spatial resolution
*Contrast resolution
*Refers to the ability to image small objects that have
high subject contrast, such as bone-soft tissue, a breast
micro-calcification, or a calcified lung nodule.
*It also refers to detail or sharpness (or visibility of
detail).
*It is measured in line pairs per millimeter (lp/mm).
*Higher resolution means more image detail.
*bone-soft tissue
*breast micro-calsifications
Spatial resolution
*It refers to the ability to
distinguish anatomical
structures of similar
contrast such as liver-spleen
and gray-white matter.
*In other words, it refers to
the differences in tissue
contrast that can be seen on
the image.
Contrast resolution
- is the Process of Converting Tissue Characteristics into a Visual Image
Medical imaging
*Difference in the image gray-scale between closely adjacent regions on the image.
Contrast
- imaging system’s ability to translate physical object contrast into image contrast.
Contrast sensitivity
*Increases Image Contrast and the Visibility of Objects in the Body
Increasing Contrast Sensitivity
Image contrast
*Low contrast (High kVp exposure)
*High contrast (low kVp exposure)
*It can be discussed in
terms of electronic noise
(system noise) and
quantum noise (quantum
mottle).
Noise
- is the result
of the variations in the
computation of pixel
value.
System noise
*is the
result of low radiation
dose. Increasing the
radiation dose decreases
noise but increases patient
dose.
Quantum mottle
*DQE refers to the efficiency of a detector in converting
incident x-ray energy into an image signal.
*It is a measure of the efficiency and fidelity with which the
detector can perform this task.
Detective Quantum Efficiency
*any false visual feature on
a medical image that
simulates tissue or
obscures tissue
*_____ therefore can be
disturbing to radiologists
and may even result in an
inaccurate diagnosis.
Artifacts
Image quality factors
*
*
*
*
*
*Resolution
*Image contrast
*Noise
*Detective Quantum Efficiency
*Artifacts
Basic concepts of image file formats
*
*
*
*
*Pixel depth
*Photometric interpretation
*Metadata
*Pixel data
- A ____ (binary digit) is the smallest
of measurement used to quantify
computer data. It contains a
single value of 0 or 1. - ____ are the basic building block
of data. - Each 1 or 0 in a binary number is
called a ___. - These binary digits are known as
____, and are the smallest possible
unit for data storage.
Bits
*This specifies the interpretation of the pixel data for
correct image display as a monochrome image or a
color image.
*Clinical radiographic image such as x-ray, computed
tomography, MRI have a gray scale photometric
interpretation.
*Nuclear medicine images like Positron Emission
Tomography and Single Photon Emission
Tomography are typically displayed with a color map
or color palette.
- Photometric Interpretation
*It is a set of data that describes and gives
information about other data.
*It is the data about other data.
*Some examples of basic _______ are author, date
created, date modified, and file size.
*_______ is also used for unstructured data such as
images, video, web pages, spreadsheets, etc.
*This is a powerful tool to
annotate and exploit
image related
information for clinical
and research purposes
and to organize and
retrieve into archives
images and associated
image data.
- Metadata
*This is the numerical values of the pixel are
stored.
*The pixels are stored in computer memory as a
raster image or raster map, a two-dimensional
array of small integers.
- Pixel Data
DATA FORMATS:
*
*
*
*
*DICOM (Digital Imaging and
Communications in Medicine) (.dcm)
*NIFTI (Neuroimaging Informatics
Technology Initiative) (.nii)
*ANALYZE (.img and .hdr)
*MNIC - Medical Imaging NetCDF
Toolkit (.mnc)
*This was created at the end of 1980’s as a format
employed by the commercial software
developed at the Mayo, Clinic, in Rochester, MN,
USA.
*This was a standard for the medical image post
processing.
Analyze
*A file format created at the beginning of 2000s
by a committee based at the National Institutes
of Health with the intent to create a format for
neuroimaging.
*It can be thought as a revised Analyze format.
NIFTI
*It was established by the American College of
Radiology and the National Electric
Manufacturers Association.
*DICOM standard is the backbone of every
medical imaging department.
*This is a standard that was made for the medical
exchange of images
DICOM
Medical Imaging Modalities
*
*
*
*
*
*Ultrasound
*CT (Computed Tomography)
*PET (Positron Emission Tomography)
*MRI (Magnetic Resonance Imaging)
*X-Ray Radiography
*This is the oldest form of medical imaging and is
frequently used.
*X-rays are produced by the transmission of x-rays
through the patient to a capture device then
converted into an image for diagnosis.
Projection Radiography/ X-ray Radiography
Components:
*________
* It is also called as the control panel that is located in a control booth which
contains protective lead shielding.
* This is the unit where the operator would select the appropriate amount of
exposure factors.
*________
* It provides electrical power to the x-ray tube
* ______
* It creates the x-ray photons
*Operating Console
* It is also called as the control panel that is located in a control booth which
contains protective lead shielding.
* This is the unit where the operator would select the appropriate amount of
exposure factors.
*High Voltage Generator
* It provides electrical power to the x-ray tube
* X-ray tube
* It creates the x-ray photons
- This is a medical imaging modality that is used to describe the use of
high frequency soundwaves. - Components: Transducer and Cathode Ray Tube
Ultrasound
- It is a device that transmits sound into the patient and received the echoes
(returning sound wavers) - It converts energy to one form to another
Transducer (Probe)
*When the transducer is placed in contact with the body, the vibrating
crystals causes the particles in the body to vibrate and theses
vibration are then passed from one layer to another.
*During its journey, the sound waves will encounter different types of
tissue and its energy loses (attenuation) due to the differing densities
of tissues..
* Echoes detected are calculated and converted into a visible image
display of the anatomic structures in a variety of shades of gray
ranging from black to white on the monitor and can be stored in the
CD for later viewing.
Imaging Principle Ultrasound
Imaging Principle:
*
*
*Conventional radiography
*Digital radiography
*It is the creation of cross sectional tomographic
section of the body using a rotating fam beam,
detector array and computed reconstruction.
*CT stand for Computed tomography from the Greek
words: TOMOS meaning SLICE and GRAPHEIN meaning
”TO WRITE”.
*CT takes images in individual slides which are
displayed independently
Computed Tomography
COMPONENTS OF CT:
*
*
*
*
*Gantry
*Sub system: X-ray tube and Detector Array
*Operating Console
*Computer
*A rotating frame containing the x-ray tube on
one side and an array of detectors on the
opposite side.
*It can be angled up to 30 degrees in each
direction
GANTRY
*This allows the technologist to control the parameters
of the examination.
*It contains controls and monitors for various imaging
technique factors
*One monitor for the technologist to annotate
patient data on the image
*Second Monitor is for the technologist to view and
manipulate the resulting image for filming and filing
OPERATING CONSOLE
- Requires a large computing capacity of about 250,000 equations that
can be solved simultaneously
*It must possess a stunning speed and memory capacity
COMPUTER
*The table moves the patient through the aperture of the CT
scanner
*While the patient is inside the aperture, the x-rat tube and
detector array within the gantry rotate simultaneously
around the patient taking picture at a time as it rotates.
*During rotation, the x-ray tube produces x-rays that will pass
through the section of the patients body and it will be
detected by the detector array and will convert the radiation
of an electrical signal that the computer will calculate the
data and construct it into an image.
IMAGING PRINCIPLE CT
*It can be defined as the use of magnetic fields
and radiowaves to obtain mathematically
reconstructed images.
MRI
MRI COMPONENTS:
*
*
*
*
*
*
MRI COMPONENTS:
*Gantry
*It contains the main magnet – the largest and most
expensive component of the MRI machine
*Qualities
*Must be large enough to surround the patient
*Must provide a uniform strong magnetic field
*COMPUTER
*It houses the electronics
necessary for overall control
of all processes.
*Qualities
*It must have high capacity to
store data and be fast to
handle number of calculation
required to produce an image
*Operating Console
*It is used for the controls of imaging process and
allows visualization of the images on the monitor.
*As the patient lie within the MRI machine, the device gives off a
strong magnetic field unto the patient.
* This will cause the atoms specifically the hydrogen atoms to line up in
the body in one direction.
*Once the atoms are lined up, the MRI machine gives of a burst of
radiofrequency waves.
* These waves causes the atoms to change in direction and when they
return to their original position, they will give off certain signals that
will be detected by the coils placed on the specific area of the body
being scanned.
IMAGING PRINCIPLE MRI
*This is a three dimensional tomographic
technique that is capable of demonstrating the
biochemical functions of the body’s organ and
tissue.
*Information obtained from positron emission
tomography is important since it reveals the
biochemical metabolism and functions of organs
and tissue
Positron Emission Tomography
- __________
- These tracers or radioactive compound
are administered to the patient by
injection or inhalation.
*When these tracers are found inside of the
body. The pet scanner detects the
radiation emitted from the tracer within
the patients anatomy.
Instrumentation
* Radiotracers
