Download 11.CT Physics Module B

Module B
Computed Tomography Physics,
Instrumentation, and Imaging
Disclaimer
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Terminology
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Algorithm- sequential set of operations
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ALARA- As Low As Reasonably
Achievable
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Aliasing- artifact
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Alphanumeric (A/N)- letters, numbers, symbols found
on a key board
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Terminology
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Analog- coding of data
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Analog-to-digital converter (ADC)transforming analog to digital
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Annotation- clinical or technical
information added to CT image
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Terminology
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Applications Program- software
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Archive- long term storage
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Arithmetic Logic Unit (ALU)computational unit or the CPU
Array- detector array- detectors used for
rapid sampling
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Terminology
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Array Processor- rapid image reconstruction
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Artifact- distortion or error on an image
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Attenuation- decrease in intensity of x-ray
as it passes through matter
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Terminology
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Attenuation Coefficient-
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Linear Attenuation Coefficient-
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Mass Attenuation Coefficient-
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Axial- perpendicular to long axis of a body
part
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Terminology
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Back-Projection-
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Simple Back-Projection-
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Summation Method-
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Terminology
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Back–projection Filtered-
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Filtered Back-Projection-
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Beam Hardening-
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Terminology
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Beam Hardening Artifact-
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Binary Coded Decimal-
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BIT- abbreviation for “binary digit”-
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Blinker Function- keyboard function
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Terminology
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Blur-
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Blurring-
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Unsharpness-
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Buffer (Buffer Memory)- peripheral
memory unit
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Terminology
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BYTE- smallest number of bits manipulated
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Calibration- assessing CT accuracy
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Central Processing Unit (CPU)- primary
computer functions
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Terminology
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Collimator- responsible for beam
reduction
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Computed Radiography- radiograph like
image
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Computer- electronic device capable of rapid
computations of information
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Terminology
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Computer Graphics- process of annotating and
labeling CT images
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Control Unit- part of CPU
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CT numbers- Hounsfield units
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Cursor- identifiable marker
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Terminology
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Data Acquisition System- components used to produce
and collect x-ray data
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Density- relative CT numbers
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Detector Array- used for rapid sampling
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Detector Efficiency- ability of the detector array
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Terminology
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Digital- coding of data
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Edge Enhancement- a technique
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Field of View (FOV)- scan field-of-view
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Filtered Back-Projection- convolutional
method
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Terminology
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Fluence- total number of photons striking
an area
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Flux- photons delivered per unit of time
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Gantry- movable frame
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Gantry aperture- central opening in the gantry
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Terminology
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Gas Detector- commonly used detector
system
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Generation- term used to classify CT
machine models
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Generator- provides electrical power
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Geometric Efficiency- detector
characteristic
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Terminology
High Resolution Contrast- ability to
reproduce tissue with high density
changes
Image Data- processed reconstructed
image data
Image Quality- degree of image
reproduction accuracy
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Terminology
Incrementation- movement of CT table relative
to the gantry
KeyboardLow Contrast Detect ability- ability of CT
system to discriminate between similar
densities
Matrix- grid of pixels
Memory- digital information storage
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Terminology
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Modulation Transfer Function-
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Monitor-
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Multi-format Camera- hardcopy device
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Noise- random fluctuations in the image
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Partial Volume Effect- condition where a voxel
is occupied by two different tissues
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Terminology
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Period- temporal or spatial duration
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Peripherals-
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Pipeline Reconstruction- technique for scanning and image
reconstruction
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Pixel- abbreviation for “picture element cell”
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Power Distribution Unit (PDU)- responsible for channeling
incoming voltage
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Terminology
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Radiotherapy Treatment Planning (RTP)- software
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RAMTEK- component which handles display capabilities
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Region (Range) of Interest (ROI)- technique used to isolate a
given value (Hounsfield number) within the image
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Reference Detectors- located at the ends of the detector array
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Reformat (Reformatted Images)-
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Terminology
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Scan- mechanical motion
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Scan Data- raw data
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Scan Projection Radiography-
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Scintillation Crystal- crystal detector which converts x-ray
energy into light energy
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Slice- cross-sectional portion
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Spatial Frequency- sinusoidal variation
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Terminology
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Spatial Resolution- capability of a system to record a
distinct image
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Spatial Uniformity-
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Storage Capacity- mega, giga, tera bytes
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Subject Contrast- actual (original) tissue
densities within the patient
Symbolic Address-
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Terminology
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Table (CT)- bed, table or portion of the unit on which
the patient is placed
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Trace-
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Transformer- component used to transfer electrical
energy
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Voxel (Volume Element)- basic volume
unit
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Window Level-
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Window Width-
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Xenon-
Terminology