Nuclear Associates 76-908 & 76-907

Operators Manual

2.2 Preparation for Scanning

2.2.1Positioning 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.

2.2.2 Scanning Parameters

For all measurements, scan conditions should be carefully recorded. Scan conditions records should include:

•Any image processing which may have been used

•Field-of-view or zoom factor

•Image matrix size

•Imaging coil

•Number of signal (excitation) acquisitions

•Phantom and phantom material

•Pulse sequence name or code and software version number

•RF power settings

•Scan timing parameters (TE, TI, TR)

•Slice excitation order

•Slice number and thickness

•Tuning parameters

2.3 Tests with 3D Resolution and Slice (3DRAS) Phantom

2.3.1 Resonance Frequency

Resonance frequency is defined as that RF frequency (f) which matches the static B-field (Bo) according to the Larmor equation. For protons, the Larmor frequency is 42.58 MHz/Tesla, e.g., for a 1.5 Tesla system, the resonance frequency should be 63.87 MHz.

Prior to the performance of any imaging protocol, the resonance frequency must be checked first. Changes in the resonance frequency reflect changes in the static magnetic field (B-field). Changes in the B-field may be due to superconductor "run down" (typically on the order of 1 ppm/day, e.g., about 60 Hz/day at 1.5 Tesla), changes in current density due to thermal or mechanical effects, shim-coil changes, or effects due to external ferromagnetic materials.

The effects of off-resonance operation relate primarily to a reduction in image signal-to-noise. Secondary effects are reflected in image linearity due to the summation of the image gradients with the inconsistent static B-field value.

It is recommended that a resonance frequency check be performed prior to any measurements and each time a different phantom is used.

The phantom is positioned in the center of the magnet (with all gradient fields turned off) and the RF frequency is adjusted by controlling the RF synthesizer center frequency to achieve maximum signal. Some resistive systems may also allow adjustment of the magnet current in order to alter the magnetic field strength so as to achieve resonance. Most vendors will provide a specific user protocol for

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Fluke 76-908, 76-907 Preparation for Scanning, Tests with 3D Resolution and Slice 3DRAS Phantom, Positioning the Phantom
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76-908, 76-907 specifications

The Fluke 76-907 and 76-908 are advanced digital multimeters designed to cater to the needs of professionals and technicians in diverse fields. Known for their accuracy, durability, and versatility, these instruments have become essential tools for electrical measurement and troubleshooting.

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The Fluke 76-907 is particularly recognized for its ergonomic design, ensuring comfort during prolonged use. It includes a built-in flashlight to illuminate dark work areas and an adjustable backlight for improved visibility of the display. Additionally, the device features a rugged casing that protects it from drops and impacts, enhancing its longevity and reliability in demanding job sites.

On the other hand, the Fluke 76-908 offers advanced features such as Bluetooth connectivity, enabling users to connect the meter to compatible smartphones and tablets. This feature allows for seamless data transfer and real-time monitoring of measurements via an intuitive app. The integration of wireless technology facilitates remote measurements, which is crucial in hazardous environments where direct access may be restricted.

Both models utilize advanced technology, including True RMS measurements, which ensure accurate readings of complex signals. This is particularly beneficial for professionals working with variable frequency drives, non-linear loads, and harmonics. The Fluke 76-907 and 76-908 also come equipped with a range of safety features, including CAT III and CAT IV ratings, ensuring they can safely handle high-voltage applications.

Battery life is another essential characteristic of these multimeters. Both models are designed for extended usage with efficient power management systems, minimizing downtime caused by battery replacements.

Furthermore, the Fluke 76-907 and 76-908 are straightforward to operate, featuring a user-friendly interface that allows technicians to navigate functions easily. They are ideal for various applications, from routine maintenance and troubleshooting in electrical systems to complex diagnostics in industrial settings.

In conclusion, the Fluke 76-907 and 76-908 digital multimeters stand out for their precise measurements, robust design, and innovative technology. Whether for fieldwork or onsite diagnostics, these multimeters provide reliability and efficiency, making them indispensable tools for professionals in the electrical industry.
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