WP 4MR design, building and testing. Leader: Julien Muller, RS2D

11/12/2014

Deliverable Report: D4.1MR System specification

Summary

1. Introduction1.1 PARTNERS INVOLVED1.2 DESCRIPTION OF DELIVERABLE CONTENT & INITIAL OBJECTIVES1.3 RELATION WITH OTHER WP

2. Main Body2.1 MATERIALS & METHODS2.2 RESULTS2.3 DISCUSSION & ANALYSIS2.4 PLANNING

3. Conclusion

1- Introduction1.1 PARTNERS INVOLVED

RS2D, JÜLICH, UNIPI, Raytest

1.2 DESCRIPTION OF DELIVERABLE CONTENT & INITIAL OBJECTIVES

Deliverable D4.1 provides the main MRI subsystems specifications (Magnet, Gradient, RF and MR electronics) together with the main selected third-party suppliers for each component

1.3 RELATION WITH OTHER WPWP3 : The PET insert between gradient coils and RF coils

2- Main body 2.1 MATERIALS & METHODS2.1.1 MR SYSTEM OVERVIEW

Operating room

Magnet Main horizontal magnetic field B0 at 1.5T

Gradient coils Space encoding gradients along the three directions X, Y and Z. Shims coils for field homogeneity correction.

Ferro shim For passive shimming

RF coil Transmission of the B1 field and reception of the MR signal

Technical room

Cryocooler Water-cooled helium gas compressor for the magnet cooling

Gradient amplifier unit Gradient current amplifier and power supply for the gradient pulse generation

Chameleon electronics Acquisition electronics (spectrometer)

RF Amplifier For the high voltage generation needed by the RF coil to generate B1 field

RF Interface box Electronics including coil identification, SAR control, active decoupling, Transmit/Receive switch

Shim power supply Shim current amplifier

Monitoring unit For the gradient monitoring and system protection

2- Main body 2.1 MATERIALS & METHODS2.1.1 MR SYSTEM OVERVIEW

SpecificationsMagnet type Cryogen-free Superconducting solenoids with self-shielding

Main field 1.5 Tesla (1H @ 64 MHz)Magnet warm bore diameter 720 mm (+/- 2 mm)Magnet bore tolerance +/- 2 mm over bore lengthField homogeneity (after ferro shim) +/- 1 ppm over 15 cm DSV

+/- 3 ppm over 22 cm DSV

Field stability (24 hours after power-up) < 0.1 ppm/hour5 Gauss line fringe field (from center) Axial < 2.8 m

Radial < 2.2 m

Operating current (Nominal) 150 ARamp Time (Approx.) 120 min.Cryostat/Magnet orientation HorizontalCooling system 1.5 W – 4 K Pulse tube by CryomechDimensions See here aboveWeight < 1500 kgKill switch included Yes

2- Main body 2.2 RESULTS2.2.1 MAGNET SPECIFICATIONS

Manufacturer :

Superconducting System Inc. SSI USA

Status : Reserved

Start of production : early 2015End of production : September 2015

2- Main body 2.2 RESULTS2.2.1 MAGNET SPECIFICATIONS

2- Main body 2.2 RESULTS2.2.2 GRADIENT SPECIFICATIONS - GRADIENT COILS

Mechanical considerationsInternal diameter 580 mm (+2 /- 1 mm)External diameter 712 mm (+1 / -2 mm)Total length 1250 mmWeigth < 650 kgBore tube Natural GRP?Mounting method Supported and clamped by multiple elastomer pads at both ends

Mounting adjustability +/- 5 mm axially, with positive axial restraint via elastomer-lined clamps

Imaging parameters X,Y Z

Strength 105 µT/m/A 103 µT/m/A

Spatial distortion -4.7 % / +1.7 % over 30 cm -4.0 % / +1.3 % over 30 cm

Residual eddy current < +/-1 % < +/-1 %

Eddy current asymmetry < 0.3 % < 0.3 %

X-Y orthogonality 90 ° +/- 0.1 ° N/A

Inductance 570 µH +/- 5 % 570 µH +/- 5 %

Resistance 200 mΩ +/- 5 % 125 mΩ +/- 5 %

Manufacturer : Tesla EngineeringUK

Status : Reserved

Start of production : early 2015

End of production :September 2015

2- Main body 2.2 RESULTS2.2.2 GRADIENT SPECIFICATIONS – 2ND ORDER SHIM COILS

Manufacturer : Tesla EngineeringUK

Status : Reserved

Start of production : early 2015

End of production :September 2015

Shim Strength over 30 cm DSV

Current Resistance Inductance Purity over 30 cm DSV

B0 12.0 µT/A 5 A 1.25 Ω 160 µH 1.2 %

Z2 8.8 µT/A 5 A 1.15 Ω 2000 µH 2.2 %

ZX 5.7 µT/A 5 A 0.35 Ω 780 µH 1.2 %

ZY 5.7 µT/A 5 A 0.35 Ω 780 µH 1.2 %

X2-Y2 3.4 µT/A 5 A 0.60 Ω 920 µH 0.7 %

XY 3.4 µT/A 5 A 0.60 Ω 920 µH 0.7 %

2- Main body 2.2 RESULTS2.2.2 GRADIENT SPECIFICATIONS – GRADIENT AMPLIFIER

Manufacturer : IECOFinland

Delivery Time:September 2015

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SpecificationsDimensions:Height 1800 mmWidth 600 mmDepth 900 mmWeight 650 kg

Output performance:

max. current +/- 400 Amax. voltage +/- 750 VInput sensitivity (Gain) 1/40 V/A

Gain accuracy and linearity < 0.05 %

Monitoring:Current monitor 1/40 V/A BNC-connectorVoltage monitor 1/100 V/V BNC-connector

2- Main body 2.2 RESULTS2.2.2 GRADIENT SPECIFICATIONS - PERFORMANCE

Gradient axis X, Y Z

Maximum strength

42 mT/m 41.2 mT/m

Rise-time to 400 A

340 µs 330 µs

Slew rate 123 T/m/s 126 T/m/s

Magnet ID 72cm Gradient ID 58cm PET ID RF coils ID 23cm Free bore

2- Main body 2.2 RESULTS2.2.3 RF SPECIFICATION – COILS – 2ND RF COIL

Manufacturer : UNIPIItaly

Delivery Time :September 2015

Specifications Tx/Rx 8 channels degenerate birdcage with distributed and lumped capacitors.

Overall Tx/Rx spec.Frequency center 64 MHzFOV 220 mm DSVHomogeneity 95 % minimum over 220 mm DSVSwitching time 20 µs transmit/receiveRing down time 20 µsMatching, Isolation < -12 dB

2- Main body 2.2 RESULTS2.2.3 RF SPECIFICATION – RF AMPLIFIER

Manufacturer : TOMCOAustralia

Delivery Time :September 2015

Specifications

Frequency range 500 kHz to 150 MHz

Gain 60 dB +/- 2dB

Peak power 2 kW

CW mode 200 W

Maximum pulse width 100 ms

Maximum duty cycle 20 %

Pulse rise time and fall time 200 ns risetime100 ns falltimeTypical using a pre-gated RF input signal

Mechanical parameters 19’’ W x 500 mm D x 225 mm H (5RU x 19’’ rack mouting)

Main power 110-240 V, 50-60 Hz, single phase, 6 kVA max

2- Main body 2.2 RESULTS2.2.3 RF SPECIFICATION – COILS – 1ST RF COIL SET

Manufacturer : JulichGermany

Delivery Time :September 2105

Specifications Tx/Rx capable actively decoupled Tx quadrature highpass birdcage coil combined with 8 channels Rx only coil.

TransmitDesign Dedicated emission outer RF coilArchitecture Quadrature birdcage with circular polarized RF fieldB1 field Minimum 2 µT/sqrt(W) – 20 µT specified to reach 100 W

ReceiveDesign Actively decoupled receive inner RF coilArchitecture 8-channel. with integrated low noise preamplifiers

Overall Tx/Rx spec.Frequency center 64 MHzFOV 220 mm DSVHomogeneity 95 % minimum over 220 mm DSVSwitching time 20 µs transmit/receiveRing down time 20 µsMatching, Isolation < -20 dB

Hardware 2- Main body 2.2 RESULTS2.2.4 ELECTRONIC SPECIFICATION – CHAMELEON : MRI CONSOLE

Manufacturer : RS2DFrance

Status : 2 units in production

SpecificationsTransmitter 64 MHz single channel (up to 4 channels from 0 to 400MHz))

16-bits phase resolution14-bits amplitude control+/- 1V maximum outputShaped pulse

Receiver 8 independent digital receivers with oversamplingAnalog to digital converter 125 MHz / 14 bits Digital filtering adjustable from 19Hz up to 4MHzUp to 80 dB gain (step of 1 dB)

Gradient 3 axis for X, Y and Z +/- 10 V peak16-bits amplitude gradient control included:Pre-emphasis adjustment and rotating matrix

Sequencer 512 sequence events per hardware line + loop counter8 ns time resolutionMinimum event duration = 80 nsUnlimited loop events32-bits loop countersExternal trigger line and up to 22 TTL user assignable control lines

WP 4 : STC Meeting 29/09/2014

Coil Interface Box

Coil interface provide Transmit /Receive switching, active decoupling and coil identification

Manufacturer : RS2D

Status : Design in progress

Hardware

Shim Power SupplyShim power supply provides DC current for the integrated shim coil of the gradient coil

Manufacturer : RS2D Status : Design complete, in production

SAR MonitoringShim power supply provides DC current for the integrated shim coil of the gradient coil

Manufacturer : RS2D Status : Design will begin 2nd quarter 2015

2- Main body 2.2 RESULTS2.2.4 ELECTRONIC SPECIFICATION – OTHER UNITS

2- Main body 2.3 DISCUSSION & ANALYSIS

Benefice of 3rd order shimming

RF amplifier and TR switch could be provided by another supplier.

Compressor dead time needed for EEG acquisition: this seems to be still an issue.

2- Main body 2.3 PLANNING

Where we are

Magnet Design complete, Start of production delayed of 3 month but

production time should not exceed

Gradient Design complete

RF coil RF Specification complete

Next period

Mechanical Design of RF coil and patient bed are waiting mechanical drawing of magnet and gradient

Electronic MRI console in productionDesign in progress

Software PET / MR interfacePulse Sequence Development

Safety in MRI scanner

The plan is :

1. Magnetic field : kill switch on the magnet2. Gradient temperature control gradient amplifier3. SAR monitoring control RF amplifier shutdown

Question : is it enough?