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Fluke 76-907, 76-908 user manual General Information, Section, Introduction, Phantom Description

Models: 76-908 76-907

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General Information

Introduction 1

Section 1

General Information

1.1 Introduction

This user's manual describes a set of MRI phantoms that were manufactured based on the AAPM recommendations and their use in measuring the MRI system performance. These phantoms were designed to measure them conveniently and quickly. The AAPM recommended image parameters described in this document are:

•Image uniformity

•Resonance frequency

•Slice position/separation

•Spatial linearity

•Phase related image artifacts

•Signal-to-noise

•Slice thickness

•Spatial resolution

This set of parameters is measured for monitoring the sensitivity and geometric characteristics of MR imaging clinical systems as specified in the AAPM document.

Two phantoms were designed to meet the AAPM specifications. This manual describes a set of test procedures associated with the phantoms that can be used to evaluate the performance of clinical magnetic resonance imaging systems. These procedures and tests, which are described in the AAPM document, can be used to establish absolute performance standards as well as routine quality assurance programs.

The manual does not include procedures to measure any T1, T2, or proton density, because at the present time there are no commonly accepted standard methods for determining T1, T2, and proton density from image data and because the assessment of these parameters is not currently a part of clinical practice.

1.2 Phantom Description

AAPM specifications provide a framework of requirements for MRI phantoms and their use, but it defines neither how phantoms should be constructed nor how inserts are to be organized. The AAPM MR Phantoms take into consideration a number of factors that maximize convenience and time efficiency for the user. The phantoms were designed to provide maximum amount of information in a reproducible manner with the shortest data acquisition time.

The set consists of two phantoms: a three dimensional resolution and slice (3DRAS) phantom and an uniformity and linearity (UAL) phantom

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Fluke 76-907, 76-908 user manual General Information, Section, Introduction, Phantom Description

Contents

Nuclear Associates 76-907 and AAPM MRI PhantomsMarch Manual No. 38616 Rev All product names are trademarks of their respective companies6045 Cochran Road Cleveland, Ohio Radiation Management ServicesFluke Biomedical Table of Contents General InformationOperations Blank page Section General Information1.1 Introduction 1.2 Phantom DescriptionResolution Block Detail - 2 Required 1.2.1 3D Resolution and Slice 3DRAS Phantom ModelFigure 1-2. Resolution Block Detail Outer Shape 6 X 6 X 5 Cubical BoxGeneral Information Figure 1-3. Resolution Sections in Three Imaging PlanesPhantom Description 2 mm Gap 1 mm Gap 1 mm GapNuclear Associates 1.2.2 Uniformity and Linearity UAL PhantomOperators Manual Figure 1-5. Slice Thickness SectionsGeneral Information MR Phantom for Spatial Linearity, Signal-To-Noise, and Image ArtifactPhantom Description UAL PhantomOperators Manual The flood phantom has a uniform solution, the image of which can be used to measure the uniformity in signal intensity in the images. The grid section consists of grids that can be used to assess geometric linearityNuclear Associates Operation 2.1.1Signal Producing Solution2.1 Phantom Preparation 2.1.2Filling the Phantom2.2 Preparation for Scanning 2.3 Tests with 3D Resolution and Slice 3DRAS Phantom2.2.1 Positioning the Phantom 2.2.2 Scanning Parameters2.3.3 High-Contrast Spatial Resolution 2.3.2 Signal-To-Noise RatioTests with 3D Resolution and Slice 3DRAS Phantom Operation2.3.5 Slice Position and Separation 2.3.4 Slice ThicknessNuclear Associates Operators ManualOperation 2.3.6 Example ImagesTests with 3D Resolution and Slice 3DRAS Phantom Operators Manual Figures 2-2 and 2-3 represent two adjacent sagital views of the phantom. The resolution holes are well resolved in vertical and horizontal direction and the two slices are 6 mm apart SP = 14.5 and 20.5. The slice thickness images of short vertical lines on top and bottom of the phantom image again are from the crossed hot ramps of 2 mm top and 1 mm bottomNuclear Associates Operation Tests with 3D Resolution and Slice 3DRAS PhantomOperators Manual Nuclear AssociatesOperation Tests with 3D Resolution and Slice 3DRAS PhantomFigures 2-7 and 2-8 show an example of the slice thickness measurement analysis. A signal intensity profile is drawn vertically through a set of slice thickness ramp Images. The profile is the slice thickness profile. One can also obtain the slice thickness by measuring full width half maximum of the profile. Figure 2-8 represents the same data using a larger zoom factor 2.4.1 Image Uniformity 2.4 Tests With Uniformity and Linearity UAL Phantom2.4.2 Spatial Linearity Distortion Nuclear AssociatesTests with Uniformity and Linearity UAL Phantom 2.4.3 Image ArtifactsOperation 2.4.5 Example Images 2.4.4 Action CriteriaDC-Offset Errors Receive Quadrature ErrorsTests with Uniformity and Linearity UAL Phantom Operation2-14 Nuclear AssociatesOperators Manual 2-15 OperationTests with Uniformity and Linearity UAL Phantom 6045 Cochran Road Cleveland, Ohio Radiation Management ServicesFluke Corporation