Endoscopic Fiber-Coupled Diamond Magnetometer for Cancer Surgery - arXiv:2504.05884v1

Aug 28, 2026

Interoperative measurements using magnetic sensors enable sensitive localization of magnetic tracers during cancer surgery. The study presents a fiber-coupled nitrogen-vacancy (NV) center magnetometer for detecting iron oxide suspension (MagTrace™) used in breast cancer procedures. Demonstrated limits include detecting 0.56 mg of iron and 2.8 mg/ml iron concentration, with performance quantified against recommended doses and distance-dependent detection up to 14.6 mm. A 10 mm sensing head supports endoscopy and laparoscopy.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages9

Reading Time23 min

AccessFree to download

Introduction

Motivation for magnetic sensing in sentinel lymph node biopsy

Limitations of radioisotopes and blue dyes

NV-center magnetometry approach

Sensitivity, sensing volume, and probe size requirements

Fiber coupling and maneuverability advantages

Experimental detail and method

Optoelectronic setup and laser/fiber parameters

Bias magnet and system configuration

Endoscopic fiber-coupled diamond magnetometer for cancer surgery A. J. Newman, 1, 2, ∗ S. M. Graham, 1, 2 C. J. Stephen, 1, 2 A. M. Edmonds,3 M. L. Markham,3 and G. W. Morley 1, 2,† 1 Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom 2 EPSRC Centre for Doctoral Training in Diamond Science and Technology, University of Warwick, Coventry CV4 7AL, United Kingdom 3 Element Six Innovation, Fermi Avenue, Harwell Oxford, Didcot OX11 0QR Oxfordshire, United Kingdom arXiv:2504.05884v1 [[physics.med-ph](physics.med-ph)] 8 Apr 2025 Interoperative measurements using magnetic sensors is a valuable technique in cancer surgery for finding magnetic tracers. Here we present a fiber-coupled nitrogen-vacancy (N-V) center magnetometer capable of detecting iron oxide suspension (MagTrace™ from Endomagnetics Ltd.) used in breast cancer surgeries. Detection of an iron mass as low as 0.56 mg has been demonstrated, 100 times less than that of a recommended dose at a maximum distance of 5 .8 mm. Detection of an iron concentration as low as 2.8 mg/ml has also been demonstrated, 20 times less than a recommended dose. The maximum working distance from the sensor can be as large as 14.6 mm for higher concentrations. The sensor head has a maximum diameter of 10 mm which would allow it to be used for endoscopy, laparoscopy and interoperative surgery. I. INTRODUCTION Non-toxic and non-radioactive techniques for finding metastasized breast cancer in lymph nodes are becoming more prevalent in hospitals around the world as magnetic based sensors have developed and are able to be used in place of blue dyes and radioisotopes [1–6] . Radioisotopes, detected using a gamma probe, are expensive and not available in all hospitals. Furthermore, using radioisotopes exposes the medical team and the patient to radiation which is preferably avoided. Blue dye can be injected into the primary tumor and accumulates in the sentinel lymph node over time, highlighting its location to the surgeon through visual inspection. Allergic reactions to blue dye have been reported in approximately one in a hundred patients [7–11] . Blue dyes also can cause long term staining of the skin atthe injection site. To mitigate the risks associated with these techniques, magnetic sensors have been increasingly utilized in sentinel lymph node biopsy (SLNB) to provide detection of nontoxic superparamagnetic iron oxide nanoparticles (SPION)[12–15] suspended in liquid which can be injected into the patient from 20 minutes to two weeks before surgery. Magnetic detection can have two operating modes, one using alternating current (AC) and a coil to generate an AC magnetic field [16–18] and the other using permanent magnets [19] . AC field methods cause the target to produce an AC magnetic field which is detected. Heating of tissue due to the frequency and amplitude of the nearby probe through Joule heating is also an issue. [20–22] . NV center magnetometry couples high dynamic range [23–25] and high magnetic sensitivity [26–29] with small sensing volumes e.g. 1 mm3 or less [23, 28 , 30–33] . The small sensor size is appropriate for SLNB applications because it reduces the volume inserted into the patient reducing trauma and bruising. Furthermore for laparoscopic surgeries, probes are limited in size by the trocar used in these procedures, typically to 12 mm diameter, which highlights the need for small probes. [34] . The ability to fiber ∗ [Alex.Newman@warwick.ac.uk](Alex.Newman@warwick.ac.uk)[ ](Alex.Newman@warwick.ac.uk)† [Gavin.Morley@warwick.ac.uk](Gavin.Morley@warwick.ac.uk) couple the diamond also provides more maneuverability when compared with a solid rod or rigid baton found in other devices [20, 35] . Sensing of magnetic fields using NV centers in diamond has previously been used to detect magnetic nanoparticles for sensing in biomedical tissue [35, 36] . One design had a non-mobile sensor head for imaging cells that had

FAQs

What magnetic tracer does the fiber-coupled NV magnetometer detect in breast cancer surgery?

It detects an iron oxide suspension (MagTrace™) used in breast cancer surgeries.

What detection performance is demonstrated for low iron mass and concentration?

The work demonstrates an iron mass detection limit of 0.56 mg and an iron concentration detection limit of 2.8 mg/ml, with reported sensitivity relative to recommended doses.

Why is the 10 mm sensor head important for surgical applications?

The maximum diameter of 10 mm supports use in endoscopy, laparoscopy, and interoperative surgery, aligning with constraints such as trocar size in laparoscopic procedures.

Aug 28, 2026

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