MagneticFieldHomogeneityMapper

Magnetic Field Homogeneity Mapper

instrumental Hyperpolarized Xenon RPH Xe-129 medical gases CSV→JSON URS & FS rule-based

Utility description: Magnetic Field Homogeneity Mapper

Magnetic Field Homogeneity Mapper — Magnetic Field Homogeneity Mapper for Hyperpolarization Systems

ℹ️  Utility analyzes magnetic field map (B0) in polarization volume:
    • Peak frequency deviation (Hz)
    • Root Mean Square inhomogeneity (RMS)
    • Uniformity in ppm

⚠️  CRITICAL: Field inhomogeneity accelerates relaxation (T2*)!
    This leads to rapid hyperpolarization loss and image blurring.

Usage:
  MagneticFieldHomogeneityMapper.exe                            → demo mode (console output)
  MagneticFieldHomogeneityMapper.exe input.csv output.json      → evaluate your data

Input format:
BatchNumber,ProductName,Central_Freq_Hz,Max_Dev_Hz,RMS_Hz,VOI_Diameter_mm,Max_Allowed_Peak_Hz,Max_Allowed_RMS_Hz

Example:
  B0-MAP-2026-001,SEOP Cell,63870000,150,40,50,200,50

— WHY IS THIS NEEDED?
Magnetic field homogeneity is critical for SEOP process:
• Hyperpolarization requires long interaction time of atoms with laser in magnetic field
• Field inhomogeneities lead to spin dephasing (shortening of T2*)
• This reduces maximum achievable polarization level
• For high-quality MRI image, field must be homogeneous within few ppm
• Field map helps adjust shimming coils

⚠️  CRITICAL:
• Peak deviation ≤200 Hz (depends on field strength)
• RMS inhomogeneity ≤50 Hz
• Uniformity < 5 ppm for high-field systems
• Regular check before each polarization series

Key features:
• NMR probe mapping data analysis
• Statistical homogeneity metrics calculation (Peak, RMS)
• Deviation conversion to relative units (ppm)
• Support for various magnet configurations

Critical parameters:
• Peak Deviation: ≤200 Hz
• RMS Inhomogeneity: ≤50 Hz
• Uniformity: < 5 ppm

💡 Usage tips:
1. Use standardized phantoms for field mapping
2. Perform shimming (passive or active) upon gradient detection
3. Account for ferromagnetic objects near installation
4. Monitor magnet temperature as it affects homogeneity
5. Save field maps to track magnet drift over time

⚠️ Note: Unlike clinical MRI scanners where homogeneity matters for image geometry, in polarizers it matters for signal creation process itself. Bad field = weak output signal, regardless of laser quality.

input.csv

BatchNumber,ProductName,Central_Freq_Hz,Max_Dev_Hz,RMS_Hz,VOI_Diameter_mm,Max_Allowed_Peak_Hz,Max_Allowed_RMS_Hz
B0-MAP-2026-001,SEOP Cell (1.5T),63870000,150,40,50,200,50
B0-MAP-2026-002,SEOP Cell (Bad Shim),63870000,800,250,50,200,50
B0-MAP-2026-003,High-Field Cell (3T),127740000,100,25,50,200,50

URS & FS — user requirements and functional specification

URS & FS — User Requirements and Functional Specification

This document defines the controlled interface and behaviour of MagneticFieldHomogeneityMapper for “Magnetic Field Homogeneity Mapper”. Limits from the source description are an initial configuration and shall be reconciled with the approved specification, study protocol, equipment instructions and local SOPs before production use.

Domain constraints and critical parameters

Peak Deviation: ≤200 Hz
RMS Inhomogeneity: ≤50 Hz
Uniformity: < 5 ppm

URS — User Requirements Specification

ID	Requirement	Criticality	Acceptance criterion
URS-001	The utility shall accept `input.csv` with the exact headers defined by the data contract.	High	The file is processed without manual header renaming.
URS-002	The utility shall perform a deterministic assessment for “Magnetic Field Homogeneity Mapper”.	High	PASS / WARNING / FAIL is produced for each row.
URS-003	Required fields, types, ranges, units and data consistency shall be validated before domain rules.	High	Schema errors are separated from nonconformities.
URS-004	Critical limits from the description and approved local configuration shall create a critical finding.	High	A critical rule violation results in FAIL.
URS-005	The result shall be written to machine-readable `output.json`.	High	JSON contains source values, checks, warnings and failures.
URS-006	The conformity decision shall not use machine learning.	Medium	The result is reproducible from explicit rules and inputs.
URS-007	Traceability of batch, source file, rule version and final status shall be retained.	High	QA/QC can reproduce the decision.
URS-008	The utility shall have exactly one primary portal tag: `instrumental`.	Medium	The other api / instrumental / medical_devices tags are absent.
URS-009	Documentation shall support IQ/OQ/PQ or equivalent CSA/CSV verification.	Medium	The contract, test scenarios and change-control rules are supplied with the utility.

input.csv data contract

#	Field	Type	Unit	Sample	Purpose
1	`BatchNumber`	string	as specified	`B0-MAP-2026-001`	Batch/lot identifier for traceability.
2	`ProductName`	string	as specified	`SEOP Cell (1.5T)`	Name of the controlled product, gas, procedure or equipment.
3	`Central_Freq_Hz`	decimal	Hz	`63870000`	Controlled input.csv field: Central Freq Hz.
4	`Max_Dev_Hz`	decimal	Hz	`150`	Controlled input.csv field: Max Dev Hz.
5	`RMS_Hz`	decimal	Hz	`40`	Controlled input.csv field: RMS Hz.
6	`VOI_Diameter_mm`	decimal	mm	`50`	Controlled input.csv field: VOI Diameter mm.
7	`Max_Allowed_Peak_Hz`	decimal	Hz	`200`	Controlled input.csv field: Max Allowed Peak Hz.
8	`Max_Allowed_RMS_Hz`	decimal	Hz	`50`	Controlled input.csv field: Max Allowed RMS Hz.

BatchNumber,ProductName,Central_Freq_Hz,Max_Dev_Hz,RMS_Hz,VOI_Diameter_mm,Max_Allowed_Peak_Hz,Max_Allowed_RMS_Hz
B0-MAP-2026-001,SEOP Cell (1.5T),63870000,150,40,50,200,50
B0-MAP-2026-002,SEOP Cell (Bad Shim),63870000,800,250,50,200,50
B0-MAP-2026-003,High-Field Cell (3T),127740000,100,25,50,200,50

FS — Functional Specification

ID	Function	Implementation
FS-001	CLI execution	`MagneticFieldHomogeneityMapper.exe` supports demo mode and `input.csv output.json` mode.
FS-002	CSV import	Read UTF-8 CSV and validate header, column count and order.
FS-003	Schema validation	Validate required values, empties, types and basic plausibility.
FS-004	Domain rule engine	Apply explicit rules for “Magnetic Field Homogeneity Mapper” and locally approved limits.
FS-005	Status aggregation	FAIL for a critical finding; WARNING for a non-critical deviation; PASS for conformity.
FS-006	JSON export	Write source values, applied rules, statuses, warnings, failures and configuration version.
FS-007	Audit support	Retain a result structure suitable for review, investigation, IQ/OQ and change control.
FS-008	Integration contract	LIMS/ELN/MES or an instrument wrapper creates CSV; the utility returns JSON.

output.json example

{
  "utilityId": "magnetic-field-homogeneity-mapper",
  "primaryTag": "instrumental",
  "overallStatus": "PASS|WARNING|FAIL",
  "sourceFile": "input.csv",
  "checks": [
    {
      "parameter": "BatchNumber",
      "value": "B0-MAP-2026-001",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "ProductName",
      "value": "SEOP Cell (1.5T)",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "Central_Freq_Hz",
      "value": "63870000",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "Max_Dev_Hz",
      "value": "150",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "RMS_Hz",
      "value": "40",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "VOI_Diameter_mm",
      "value": "50",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "Max_Allowed_Peak_Hz",
      "value": "200",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "Max_Allowed_RMS_Hz",
      "value": "50",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    }
  ],
  "warnings": [],
  "criticalFindings": []
}

OQ/PQ test scenarios

ID	Scenario	Expected result
OQ-001	Valid example row	PASS or an allowed WARNING under local rules.
OQ-002	Required column missing	Schema error; domain checks do not mask it.
OQ-003	Non-numeric value in numeric field	Type-conversion error.
OQ-004	Critical parameter outside its limit	FAIL and a critical finding.
OQ-005	Boundary value	The result follows the configured ≤ / ≥ / < / > operator.
PQ-001	Real site data	Agreed QA/QC review retaining CSV, JSON, version and checksum.

QA/QC and change control

Do not change column names without updating the validator, documentation and test set.
Retain input.csv, output.json, executable version, rule version and checksums.
Before production use, verify local limits and execute IQ/OQ/PQ or equivalent CSA.
Changes affecting patient safety, dosimetry, gas composition, polarization or equipment require documented impact assessment.

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