Medical screening is an important tool that improves clinicians’ efficacy in identifying any abnormality, usually in a non-invasive way. Conventional state of the art medical imaging technologies, such as ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and X-ray are widely used for cancer diagnosis, bone imaging, tumour detection, musculoskeletal disorders, appendicitis, infectious diseases and trauma. These imaging tools provide clinical information with a variety of resolutions, implementation costs and complexity of use, and some of them depend on ionising radiation.
Though MRI scanning provides good resolution, it is a costly procedure and has a long examination time, making it inconvenient for the patient. CT is more powerful than X-ray; however, both techniques use ionising radiation. Such techniques are harmful as they interact with tissues in the patient’s body either through absorption or scattering, which may increase the risk of cancer. Furthermore, though a mammography exam uses a low-dose X-ray, patients will have to tolerate the discomfort during examinations. Even though the ultrasound is a non-ionising imaging technique, it cannot penetrate air and bones, and its strong reflections cause acoustic shadows.
Microwave sensing and imaging (MSI) provides an alternative novel method based on non-ionising electromagnetic signals, hence low health risk, cost implementation and operational cost, and it is user-friendly. Due to advancements achieved in microelectronics, material science and embedded systems, it is possible to make MSI systems portable, handheld and with networking capabilities. The medical application of MSI potentially enhances diagnostic capability and accuracy allowing for earlier diagnosis. Biomedical imaging systems based on MSI received interest over the last years, particularly for breast cancer detection, blood clot/stroke detection, lung cancer, skin lesion, bone fracturing and localisation of in-body radio frequency sources.
Tomographic and confocal imaging techniques have been developed and some have undergone clinical trials, such as breast cancer imaging systems and a helmet designed for stroke detection. This indicates the potential to match current state of the art imaging techniques.
Usually, MSI systems are implemented such that they are integrated with signal or image pre-processing segmentation which employs machine learning techniques for automated diagnosis processes. Such processes will provide insights for healthcare providers to evaluate their patients efficiently, accurately, and quickly, whether in a hospital or remotely. Though MSI has shown remarkable potential for medical applications, the clinical approval of the technology is pending further improvement to address clinical and commercial challenges.
Iman Farhat, researcher, antenna designer, radio astronomy
Did you know?
• Lungs do more than help us breathe – in mammals they also produce more than 10 tiny blood cells per hour.
• Polar bears are nearly undetectable by infrared cameras.
• Volcanic lightning is the result of electrification of ash by lava.
• It takes a photon up to 40,000 years to travel from the core of the sun to its surface, but only eight minutes to travel the rest of the way to earth.
For more trivia see: www.um.edu.mt/think
Sound bites
• Using the radio-based Event Horizon Telescope (EHT), researchers performed an extraordinary observation, the likes of which remains a dream for most other astronomers. The EHT team announced in April 2019 that it had successfully imaged the shadow of a supermassive black hole in a nearby galaxy by combining observations from eight different radio telescopes spread across our planet.
• Ever since their discovery in the 1960s, ultra-high energy cosmic rays have captivated scientists, who wonder where they come from. Like all cosmic rays, they are arguably misnamed: they are not ‘rays’ of radiation but rather subatomic particles, such as protons or even entire nuclei, zipping through space. Such ultra-high energies come from ultra-high speeds, approaching that of light itself.
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