module b computed tomography physics, instrumentation, and imaging

Module BModule B

Computed Tomography Computed Tomography Physics, Instrumentation, Physics, Instrumentation,

and Imagingand Imaging

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TerminologyTerminology

Algorithm- sequential set of operationsAlgorithm- sequential set of operations

ALARA- As Low As Reasonably ALARA- As Low As Reasonably AchievableAchievable

Aliasing- artifactAliasing- artifact

Alphanumeric (A/N)- letters, numbers, Alphanumeric (A/N)- letters, numbers, symbols found on a key boardsymbols found on a key board

Continue…..Continue…..Terminology Terminology

Analog- coding of dataAnalog- coding of data

Analog-to-digital converter (ADC)- Analog-to-digital converter (ADC)- transforming analog to transforming analog to

digitaldigital

Annotation- clinical or technical Annotation- clinical or technical information added to CT information added to CT

image image

Continue…..Continue…..TerminologyTerminology

Applications Program- softwareApplications Program- software

Archive- long term storageArchive- long term storage

Arithmetic Logic Unit (ALU)- Arithmetic Logic Unit (ALU)- computational unit or the CPUcomputational unit or the CPU

Array- detector array- detectors used Array- detector array- detectors used for for rapid samplingrapid sampling


Array Processor- rapid image Array Processor- rapid image reconstructionreconstruction

Artifact- distortion or error on an Artifact- distortion or error on an imageimage

Attenuation- decrease in intensity of Attenuation- decrease in intensity of x-ray x-ray as it passes through as it passes through mattermatter


Attenuation Coefficient-Attenuation Coefficient-

Linear Attenuation Coefficient-Linear Attenuation Coefficient-

Mass Attenuation Coefficient-Mass Attenuation Coefficient-

Axial- perpendicular to long axis of a Axial- perpendicular to long axis of a body body partpart


Back-Projection-Back-Projection-

Simple Back-Projection-Simple Back-Projection-

Summation Method-Summation Method-


Back–projection Filtered-Back–projection Filtered-

Filtered Back-Projection- Filtered Back-Projection-

Beam Hardening-Beam Hardening-


Beam Hardening Artifact-Beam Hardening Artifact-

Binary Coded Decimal-Binary Coded Decimal-

BIT- abbreviation for “binary digit”-BIT- abbreviation for “binary digit”-

Blinker Function- keyboard functionBlinker Function- keyboard function


Blur-Blur-

Blurring-Blurring-

Unsharpness-Unsharpness-

Buffer (Buffer Memory)- peripheral Buffer (Buffer Memory)- peripheral memory memory

unitunit


BYTE- smallest number of bits BYTE- smallest number of bits manipulatedmanipulated

Calibration- assessing CT accuracyCalibration- assessing CT accuracy

Central Processing Unit (CPU)- Central Processing Unit (CPU)- primary primary computer functionscomputer functions


Collimator- responsible for beam Collimator- responsible for beam reductionreduction

Computed Radiography- radiograph Computed Radiography- radiograph like like image image

Computer- electronic device capable Computer- electronic device capable of rapid computations of informationof rapid computations of information


Computer Graphics- process of Computer Graphics- process of annotating and labeling CT imagesannotating and labeling CT images

Control Unit- part of CPUControl Unit- part of CPU

CT numbers- Hounsfield unitsCT numbers- Hounsfield units

Cursor- identifiable markerCursor- identifiable marker


Data Acquisition System- components Data Acquisition System- components used to produce and collect x-ray dataused to produce and collect x-ray data

Density- relative CT numbersDensity- relative CT numbers

Detector Array- used for rapid samplingDetector Array- used for rapid sampling

Detector Efficiency- ability of the Detector Efficiency- ability of the detector arraydetector array


Digital- coding of dataDigital- coding of data

Edge Enhancement- a technique Edge Enhancement- a technique

Field of View (FOV)- scan field-of-viewField of View (FOV)- scan field-of-view

Filtered Back-Projection- convolutional Filtered Back-Projection- convolutional methodmethod


Fluence- total number of photons striking Fluence- total number of photons striking an areaan area

Flux- photons delivered per unit of timeFlux- photons delivered per unit of time

Gantry- movable frameGantry- movable frame

Gantry aperture- central opening in the Gantry aperture- central opening in the gantrygantry

Continue…..Continue…..TerminologyTerminology Gas Detector- commonly used detector Gas Detector- commonly used detector

systemsystem

Generation- term used to classify CT Generation- term used to classify CT machine modelsmachine models

Generator- provides electrical powerGenerator- provides electrical power

Geometric Efficiency- detector Geometric Efficiency- detector characteristiccharacteristic


High Resolution Contrast- ability to High Resolution Contrast- ability to reproduce tissue with reproduce tissue with

high density high density changeschanges Image Data- processed reconstructed Image Data- processed reconstructed

image dataimage data

Image Quality- degree of image Image Quality- degree of image reproduction reproduction

accuracy accuracy


Incrementation- movement of CT Incrementation- movement of CT table relative to the gantrytable relative to the gantry

Keyboard-Keyboard- Low Contrast Detect ability- ability Low Contrast Detect ability- ability

of CT of CT system to discriminate system to discriminate between similar between similar densitiesdensities

Matrix- grid of pixelsMatrix- grid of pixels Memory- digital information storageMemory- digital information storage

Continue…..Continue…..TerminologyTerminology Modulation Transfer Function-Modulation Transfer Function-

Monitor-Monitor-

Multi-format Camera- hardcopy deviceMulti-format Camera- hardcopy device

Noise- random fluctuations in the imageNoise- random fluctuations in the image

Partial Volume Effect- condition where a Partial Volume Effect- condition where a voxel voxel is occupied by two is occupied by two different tissuesdifferent tissues

Continue…..Continue…..TerminologyTerminology Period- temporal or spatial durationPeriod- temporal or spatial duration

Peripherals- Peripherals-

Pipeline Reconstruction- technique for scanning Pipeline Reconstruction- technique for scanning and image reconstructionand image reconstruction

Pixel- abbreviation for “picture element cell”Pixel- abbreviation for “picture element cell”

Power Distribution Unit (PDU)- responsible for Power Distribution Unit (PDU)- responsible for channeling incoming voltagechanneling incoming voltage

Continue…..Continue…..TerminologyTerminology Radiotherapy Treatment Planning (RTP)- softwareRadiotherapy Treatment Planning (RTP)- software

RAMTEK- component which handles display RAMTEK- component which handles display capabilitiescapabilities

Region (Range) of Interest (ROI)- technique used Region (Range) of Interest (ROI)- technique used to isolate a given value (Hounsfield number) within to isolate a given value (Hounsfield number) within the imagethe image

Reference Detectors- located at the ends of the Reference Detectors- located at the ends of the detector arraydetector array

Reformat (Reformatted Images)-Reformat (Reformatted Images)-

Continue…..Continue…..TerminologyTerminology Scan- mechanical motionScan- mechanical motion

Scan Data- raw dataScan Data- raw data

Scan Projection Radiography- Scan Projection Radiography-

Scintillation Crystal- crystal detector which Scintillation Crystal- crystal detector which converts x-ray energy into light energyconverts x-ray energy into light energy

Slice- cross-sectional portionSlice- cross-sectional portion

Spatial Frequency- sinusoidal variationSpatial Frequency- sinusoidal variation

Continue…..Continue…..TerminologyTerminology Spatial Resolution- capability of a system Spatial Resolution- capability of a system

to record a distinct image to record a distinct image

Spatial Uniformity- Spatial Uniformity-

Storage Capacity- mega, giga, tera bytesStorage Capacity- mega, giga, tera bytes

Subject Contrast- actual (original) tissue Subject Contrast- actual (original) tissue densities within densities within

the patientthe patient Symbolic Address-Symbolic Address-

Continue…..Continue…..TerminologyTerminology Table (CT)- bed, table or portion of the Table (CT)- bed, table or portion of the

unit on which the patient is placedunit on which the patient is placed

Trace- Trace-

Transformer- component used to transfer Transformer- component used to transfer electrical energy electrical energy

Voxel (Volume Element)- basic volume Voxel (Volume Element)- basic volume unitunit


Window Level-Window Level-

Window Width-Window Width-

Xenon-Xenon-

module b computed tomography physics, instrumentation, and imaging

Documents

unit o

labeling ct imagescontrol

projection beam hardening

rapid samplingcontinue

technical information

projectionsummation

terminology analog coding

long axis