Table of Contents
Related Manuals for Fluke Nuclear Associates 76-907
Summary of Contents for Fluke Nuclear Associates 76-907
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Page 1: Users Manual
Nuclear Associates 76-907 and 76-908 AAPM MRI Phantoms Users Manual March 2005 Manual No. 38616 Rev. 3 ©2003, 2005 Fluke Corporation, All rights reserved. Printed in U.S.A. All product names are trademarks of their respective companies... - Page 2 Fluke Biomedical Radiation Management Services 6045 Cochran Road Cleveland, Ohio 44139 440.498.2564 www.flukebiomedical.com/rms...
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Page 3: Table Of Contents
Table of Contents Section 1: General Information................... 1-1 Introduction ....................1-1 Phantom Description..................1-1 1.2.1 3D Resolution and Slice (3DRAS) Phantom (Model 76-908) ....1-2 1.2.2 Uniformity and Linearity (UAL) Phantom (76-907)........1-4 Section 2: Operations....................2-1 Phantom Preparation ................... 2-1 2.1.1 Signal Producing Solution .............. - Page 4 (Blank page)
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Page 5: General Information
General Information Introduction 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: •... -
Page 6: Resolution And Slice (3Dras) Phantom (Model 76-908)
Nuclear Associates 76-908 & 76-907 Operators Manual 1.2.1 3D Resolution and Slice (3DRAS) Phantom (Model 76-908) The 3DRAS phantom has outer dimensions of 6" x 6" x 5" (Figure 1-1). Six resolution inserts and slice thickness 4 ramp sets were placed inside of the rectangular box to allow image acquisition in any one of the three directions (sagital, coronal, and transaxial) without repositioning the phantom. - Page 7 General Information Phantom Description Filling Hole ( ¼”) 2 mm Gap Resolution Block W/Horizontal Holes Resolution Blocks w/Holes into the Paper Resolution Blocks w/Vertical Holes Slice Thickness 1 mm Gap Block Groups (4) Box Dimension of the Box 6: x 6: Walls are Made with ¼”...
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Page 8: Uniformity And Linearity (Ual) Phantom (76-907)
Nuclear Associates 76-908 & 76-907 Operators Manual A ramp-crossing angle of 90° yields an angle of 45° between the ramp and the imaging slice plane. Each slice thickness section consists of four triangular blocks arranged to form (signal producing) hot ramps filling the gaps of 1 mm or 2 mm (Figure 1-5). - Page 9 General Information Phantom Description MR Phantom for Spatial Linearity, Signal-To-Noise, and Image Artifact Glue Glue Linearity Grid, Light Cover 13” Glue, Orientation References Glue Glue 13” Not To Scale Figure 1-6. UAL Phantom MRI Phantom for Spatial Linearity, Signal-To-Noise, and Image Artifact Glue Glue Glue 3/16”...
- Page 10 Nuclear Associates 76-908 & 76-907 Operators 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 linearity.
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Page 11: Operations
Operation Phantom Preparation Section 2 Operation 2.1 Phantom Preparation The phantoms can be shipped filled with solutions or solutions can be shipped separately. Each user can also prepare a solution. 2.1.1 Signal Producing Solution At each operating field strength, AAPM recommends that the chosen NMR material should exhibit the following characteristics: 100 msec <... -
Page 12: Preparation For Scanning
Nuclear Associates 76-908 & 76-907 Operators Manual 2.2 Preparation for Scanning 2.2.1 Positioning the Phantom The 3DRAS phantom can be placed in a head coil or a body coil. The center of the phantom should coincide approximately with the center of the RF coil. The UAL phantom can be used only with a body coil. -
Page 13: Signal-To-Noise Ratio
Operation Tests with 3D Resolution and Slice (3DRAS) Phantom resonance frequency adjustment and some may be completely automated. Resonance frequency should be recorded daily for trend analysis. Values of resonance frequency should generally not deviate by more than 50 ppm between successive daily measurements. -
Page 14: Slice Thickness
Nuclear Associates 76-908 & 76-907 Operators Manual • The high contrast resolution should remain constant for repeated measurements under the same scan conditions and should be equal to the pixel size. For example, for a 25.6 cm field of view with a 256 x 256 acquisitions matrix, the resolution should be 1 mm. -
Page 15: Example Images
Operation Tests with 3D Resolution and Slice (3DRAS) Phantom direction) is measured and related to the slice position. For a 45° ramp, the distance from a centered reference pin to the slice profile midpoint will be equal to the point of the ramps located at the isocenter. All measurements should be made along the line made up of the magnet isocenter and the centers of the imaging planes. - Page 16 Nuclear Associates 76-908 & 76-907 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 (bottom).
- Page 17 Operation Tests with 3D Resolution and Slice (3DRAS) Phantom Figures 2-4 and 2-5 show two adjacent coronal views of the phantom. The slice thickness lines of 1 mm ramps on the right and bottom of the images are too faint to be seen. Figure 2-4.
- Page 18 Nuclear Associates 76-908 & 76-907 Operators Manual Figure 2-6 shows a resolution hole image against a background less opaque than in previous images, indicating that the position of the resolution block is such that it is partially covered by the slice. For resolution measure, it is advised to use a slice that covers the central portion of the slice hole section.
- Page 19 Operation Tests with 3D Resolution and Slice (3DRAS) Phantom Figures 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.
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Page 20: Tests With Uniformity And Linearity (Ual) Phantom
Nuclear Associates 76-908 & 76-907 Operators Manual 2.4 Tests With Uniformity and Linearity (UAL) Phantom 2.4.1 Image Uniformity Image uniformity refers to the ability of the MR imaging system to produce a constant signal response throughout the scanned volume when the object being imaged has homogeneous MR characteristics. Factors Affecting Image Uniformity include: (1) Static-field inhomogeneities (2) RF field non-uniformity... -
Page 21: Image Artifacts
Operation Tests with Uniformity and Linearity (UAL) Phantom (2) Non-linear magnetic field gradients Variability is best observed over the largest field-of-view. The phantom should occupy at least 60% of the largest field-of-view. Figure 1-1 provides an illustration of a pattern that is used to evaluate spatial linearity. -
Page 22: Action Criteria
Nuclear Associates 76-908 & 76-907 Operators Manual DC-Offset Errors DC-offset errors typically appear as a single bright pixel (sometimes as a dark pixel if overflow or processing has occurred) at the center of the image matrix. The existence of this error is assessed visually. - Page 23 Operation Tests with Uniformity and Linearity (UAL) Phantom Figure 2-9 2-13...
- Page 24 Nuclear Associates 76-908 & 76-907 Operators Manual Figure 2-10 is a flood image showing the uniformity of signal intensity. Field non-uniformity is also shown on the outer edges. Figure 2-10 Figure 2-11 shows a horizontal intensity profile with a narrow window setting. Such information can be used as baseline data.
- Page 25 Operation Tests with Uniformity and Linearity (UAL) Phantom Figure 2-12 is an image of the signal bubble for quadrature error. If there were any quadrature phase error, another ghost circle would be visible in the lower right-hand corner of the image. Quadrature error has become less common in most of the recent MRI systems.
- Page 26 Fluke Corporation Radiation Management Services 6045 Cochran Road Cleveland, Ohio 44139 440.498.2564 www.flukebiomedical.com/rms...