Microwave kinetic inductance detectors (MKIDs) are being presented as a possible next-generation platform for medical imaging, combining single-photon counting with intrinsic wavelength or energy resolution, very low noise and detector arrays that can be scaled up. A technical review examines four proposed areas: fluorescence microscopy, near-infrared spectroscopy (NIRS), energy-resolved medical X-rays and synchrotron X-ray microscopy. Its message is ambitious but preliminary. The paper reports no recruited human or animal participants, specimens, laboratory samples or original clinical dataset, so it offers no clinical validation of benefit.
A map of possible uses
Rather than report an original experiment, the authors make a descriptive technical comparison between MKIDs, thermal kinetic inductance detectors (TKIDs) for X-rays and current detector technologies. The paper reports no preregistration, sample-size rationale, randomization, controlled head-to-head experiment or inferential statistical analysis. Its performance figures therefore bring together cited detector demonstrations and technical projections across selected imaging fields, rather than results from one common test.
The case for keeping more light information
Fluorescence microscopy is the first case. The review describes MKIDs as offering single-photon counting, virtually no dark counts and wavelength resolving power up to R ~ 52. Resolving power is a measure of how finely a detector can separate nearby wavelengths. MKIDs can also use frequency-domain multiplexing for large arrays, the authors say, and their expected penetration depth is described as similar to that of SNSPDs.
The review frames this combination as a proposed advantage over photomultiplier tubes (PMTs) and SNSPDs. A detector that counts individual photons while retaining wavelength information could offer fluorescence systems more information in each measurement, but the paper does not report a new fluorescence experiment. The proposed penetration-depth comparison and large-array use remain expectations based on detector properties rather than clinical findings.
More pixels for near-infrared scans
The review then turns to near-infrared spectroscopy, or NIRS, for brain imaging. It says MKIDs could be multiplexed to 2,000 pixels on a single feedline, while competing superconducting detectors have difficulty reaching more than 500 pixels. In plain terms, the paper is arguing that one readout path could support a much denser detector array. That is linked to the prospect of more complete sampling across the head, but the review does not report a whole-head clinical demonstration.
Spectral detail is the second proposed gain. The authors say MKIDs could perform basic NIRS discrimination at resolving power of about R ~ 10 by separating wavelengths associated with oxygenated and deoxygenated haemoglobin. Higher resolving power could allow the system to distinguish additional chromophores, the light-absorbing compounds used in the measurement. The same intrinsic wavelength resolution could reduce the need for filters or switching between wavelengths, according to the review. These benefits remain proposed rather than measured in the paper.
For breast diffuse optical tomography using NIRS, the paper makes a further projection. Large MKID arrays and a higher signal-to-noise ratio—more useful signal relative to background noise—could improve oversampling and tumour localization beyond a reported 5 mm² limit. The wording matters: this is a projection about what array size and signal quality might make possible, not a breast-imaging experiment or a diagnostic validation study. No clinical performance is established.
X-rays expose the engineering trade-offs
For energy-resolved medical X-rays, the review discusses TKIDs alongside TES detectors. Energy resolution describes how closely a detector can tell two incoming X-ray energies apart. Cited demonstrations in the 6 keV range report resolution of up to 1.8 eV for TESs and 41 eV for TKIDs. The review says TKIDs still offer substantially finer reported resolution than semiconductor alternatives, but the cited TES performance is better. Those figures come from cited demonstrations and early TKID development, not a common head-to-head test.
Cooling is another dividing line. The paper describes TESs as requiring temperatures below 80 mK, while TKIDs operate between 150 and 200 mK. The authors regard TKID implementation as less challenging for clinical environments, a potential engineering advantage rather than a result from hospital deployment. Complex cryogenic and readout systems nevertheless remain practical hurdles in the review’s account.
The proposed dose benefit is even more conditional. The authors suggest that TKIDs could distinguish many contrast agents at the same time in a single-pass X-ray, potentially reducing ionising irradiation and the burden of diagnosis. But the paper reports no dose measurement, clinical comparison or patient outcome study. The claim is therefore about what energy-resolved detection might enable, not about a reduction already observed in patients.
A fast, scalable option for synchrotron microscopy
In synchrotron X-ray microscopy, the review highlights a different combination of capabilities. It describes TKIDs with 41 eV energy resolution at 6 keV, arrays of up to 20k pixels and photon-arrival time stamping better than 1 μs. The timing figure refers to how precisely the system records when a photon arrives. The authors say future improvement in resolution and megapixel arrays are feasible, but those larger arrays and future gains are not demonstrated in this review.
Across the four cases, the authors’ conclusion is that MKIDs and TKIDs could combine photon counting, intrinsic energy resolution, very low noise and scalable arrays in ways that merit further development. That is why the paper describes them as a compelling next-generation medical-imaging technology. It is a hypothesis-generating engineering case, not a finding of clinical efficacy or patient safety.
What has to be shown next
The gap is not a minor footnote. The paper acknowledges that MKIDs remain in an early development phase and that practical systems must handle complex cryogenic and readout requirements. Because the review does not report a controlled head-to-head experiment, its cited figures do not amount to a single like-for-like contest. No direct human validation, diagnostic-accuracy study, patient outcome study or radiation-dose trial is reported.
Questions left open include whether MKID and TKID arrays can achieve their proposed performance under clinical imaging conditions, whether their cryogenic and readout requirements can be integrated into practical systems, and whether any detector advantage improves validated image quality, diagnostic accuracy or radiation dose. The review identifies those questions but cannot answer them with its narrative comparison. For now, its value is as a technical map of where superconducting detectors might fit, not as evidence that they improve care.
Paper data and sources
Original title: An Overview of Potential Medical Applications of Microwave Kinetic Inductance Detectors
Authors: Cáthal McAleer, Gary Donegan, Colm Bracken et al.
Journal/Repository: IEEE Transactions on Applied Superconductivity (2026)
Status: Peer-reviewed
First online: 2026-08-20
DOI: 10.1109/tasc.2026.3707759
Original paper · Full text