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