Transcript 11.CT Physics Module B

Module B
Computed Tomography Physics,
Instrumentation, and Imaging
Disclaimer

This workforce solution was funded by a grant awarded under the President’s
Community-Based Job Training Grants as implemented by the U.S.
Department of Labor’s Employment and Training Administration. The
solution was created by the grantee and does not necessarily reflect the official
position of the U.S. Department of Labor. The Department of Labor
makes no guarantees, warranties, or assurances of any kind, express or
implied, with respect to such information, including any information on
linked sites and including, but not limited to, accuracy of the information or
its completeness, timeliness, usefulness, adequacy, continued availability, or
ownership. This solution is copyrighted by the institution that created
it. Internal use by an organization and/or personal use by an individual for
non-commercial purposes is permissible. All other uses require the prior
authorization of the copyright owner.
Terminology

Algorithm- sequential set of operations

ALARA- As Low As Reasonably
Achievable

Aliasing- artifact

Alphanumeric (A/N)- letters, numbers, symbols found
on a key board
Continue…..
Terminology

Analog- coding of data

Analog-to-digital converter (ADC)transforming analog to digital

Annotation- clinical or technical
information added to CT image
Continue…..
Terminology

Applications Program- software

Archive- long term storage

Arithmetic Logic Unit (ALU)computational unit or the CPU
Array- detector array- detectors used for
rapid sampling

Continue…..
Terminology

Array Processor- rapid image reconstruction

Artifact- distortion or error on an image

Attenuation- decrease in intensity of x-ray
as it passes through matter
Continue…..
Terminology

Attenuation Coefficient-

Linear Attenuation Coefficient-

Mass Attenuation Coefficient-

Axial- perpendicular to long axis of a body
part
Continue…..
Terminology

Back-Projection-

Simple Back-Projection-

Summation Method-
Continue…..
Terminology

Back–projection Filtered-

Filtered Back-Projection-

Beam Hardening-
Continue…..
Terminology

Beam Hardening Artifact-

Binary Coded Decimal-

BIT- abbreviation for “binary digit”-

Blinker Function- keyboard function
Continue…..
Terminology

Blur-

Blurring-

Unsharpness-

Buffer (Buffer Memory)- peripheral
memory unit
Continue…..
Terminology

BYTE- smallest number of bits manipulated

Calibration- assessing CT accuracy

Central Processing Unit (CPU)- primary
computer functions
Continue…..
Terminology

Collimator- responsible for beam
reduction

Computed Radiography- radiograph like
image

Computer- electronic device capable of rapid
computations of information
Continue…..
Terminology

Computer Graphics- process of annotating and
labeling CT images

Control Unit- part of CPU

CT numbers- Hounsfield units

Cursor- identifiable marker
Continue…..
Terminology

Data Acquisition System- components used to produce
and collect x-ray data

Density- relative CT numbers

Detector Array- used for rapid sampling

Detector Efficiency- ability of the detector array
Continue…..
Terminology

Digital- coding of data

Edge Enhancement- a technique

Field of View (FOV)- scan field-of-view

Filtered Back-Projection- convolutional
method
Continue…..
Terminology

Fluence- total number of photons striking
an area

Flux- photons delivered per unit of time

Gantry- movable frame

Gantry aperture- central opening in the gantry
Continue…..
Terminology

Gas Detector- commonly used detector
system

Generation- term used to classify CT
machine models

Generator- provides electrical power

Geometric Efficiency- detector
characteristic
Continue…..



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
Continue…..





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
Continue…..
Terminology

Modulation Transfer Function-

Monitor-

Multi-format Camera- hardcopy device

Noise- random fluctuations in the image

Partial Volume Effect- condition where a voxel
is occupied by two different tissues
Continue…..
Terminology

Period- temporal or spatial duration

Peripherals-

Pipeline Reconstruction- technique for scanning and image
reconstruction

Pixel- abbreviation for “picture element cell”

Power Distribution Unit (PDU)- responsible for channeling
incoming voltage
Continue…..
Terminology

Radiotherapy Treatment Planning (RTP)- software

RAMTEK- component which handles display capabilities

Region (Range) of Interest (ROI)- technique used to isolate a
given value (Hounsfield number) within the image

Reference Detectors- located at the ends of the detector array

Reformat (Reformatted Images)-
Continue…..
Terminology

Scan- mechanical motion

Scan Data- raw data

Scan Projection Radiography-

Scintillation Crystal- crystal detector which converts x-ray
energy into light energy

Slice- cross-sectional portion

Spatial Frequency- sinusoidal variation
Continue…..
Terminology

Spatial Resolution- capability of a system to record a
distinct image

Spatial Uniformity-

Storage Capacity- mega, giga, tera bytes

Subject Contrast- actual (original) tissue
densities within the patient
Symbolic Address-

Continue…..
Terminology

Table (CT)- bed, table or portion of the unit on which
the patient is placed

Trace-

Transformer- component used to transfer electrical
energy

Voxel (Volume Element)- basic volume
unit
Continue…..

Window Level-

Window Width-

Xenon-
Terminology