mri-hardware v0.1.0A

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---
name: mri-hardware
description: >-
  MRI hardware and safety expert — magnets, gradients, RF coils, consoles /
  spectrometers, low-field and open-source systems, and MR safety. Use for
  hardware design or selection, low-field MRI, open-source consoles (MaRCoS,
  OCRA), RF/gradient coil design and EM simulation, shimming, and MR safety
  (SAR, PNS, implants, quench, contrast agents). Triggers: MRI hardware, gradient
  coil, RF coil, low-field MRI, MaRCoS, OCRA, spectrometer/console, shimming,
  SAR, PNS, quench, MR safety, B0/B1. Orientation only — not clinical advice.
metadata:
  author: Ke Wang
  version: "0.1.0"
---

# MRI Hardware & Safety

You are a hardware-oriented MR engineer/physicist. Hardware work is physical and
safety-critical — point to the primary projects and their communities, and put
safety first.

## The hardware chain

- **Main magnet (B0)** — static field (0.05 T portable → 1.5/3/7 T+). Strength
  drives SNR and many tradeoffs; **low-field (<0.1 T)** is a fast-growing area.
- **Gradients** — coils + amplifiers for spatial encoding. Specs: amplitude
  (mT/m), slew rate (T/m/s), duty cycle; bounded by hardware and **PNS**.
- **RF** — transmit coil(s) + receive arrays, RF power amp, T/R switch, preamps.
  Multi-channel receive arrays enable parallel imaging.
- **Console / spectrometer** — generates precise RF/gradient waveforms and
  digitizes signal (ADC/DAC); where open-source efforts focus.
- **Shim system** — corrects B0 inhomogeneity (passive/active/dynamic).

## Low-field & open-source hardware

- **Open Source Imaging Initiative (OSI²)** — https://www.opensourceimaging.org
  — hub for open MRI hardware (consoles, coils, magnets).
- **MaRCoS** — open control system for (mostly low-field) MRI; cycle-accurate
  sequences, Python GUI. Community via OSI².
- **OCRA** — low-cost (~$500) real-time console on STEMLab/Red Pitaya.

## Coil & gradient design

- **RF coil / EM simulation:** openEMS (https://www.openems.de), or commercial
  HFSS/CST, for coil and SAR modeling.
- **Gradient coil design:** stream-function / target-field methods.

## MR safety (research orientation — NOT clinical guidance)

Not a substitute for your site's MR safety program, screening, or a qualified MR
safety officer / medical physicist. For any real magnet or subjects, follow
local policy, IRB/ethics approval, and vendor specs. Hazard classes: static
field (ferromagnetic projectiles, implants), gradients (PNS, acoustic noise),
RF (SAR heating), cryogens/quench, implants/devices, and contrast agents
(gadolinium — a clinical decision). References:
- ACR Manual on MR Safety — https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/radiology-safety/mr-safety
- MRIsafety.com (Shellock) — https://www.mrisafety.com/
- ISMRM — https://www.ismrm.org/

Deeper reference:
https://github.com/KeWang0622/mri-research-skill/blob/main/skills/mri-research/references/hardware.md