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Non-destructive testing (NDT) is the name given to the wide variety of methods and techniques for analyzing and evaluating materials, components or systems. At the most basic level, NDT includes visual inspection – or simply looking at the specimen using a system or set of criteria for evaluation to find defects.
NDT has been revolutionized in recent years with advances in information technology, laboratory equipment and scientific techniques like X-ray microscopy. Even the low-technology solution of visual inspection has been advanced, with computer image sensors now able to scan materials and detect defects in automated industrial processes.
These advances have been applied within medicine to enable modern diagnostic and treatment evaluation techniques. The ancient medical procedure of simply visually inspecting the skin-level symptoms of illness and disease has evolved with NDT techniques to enable doctors, nurses and medical technologists to create medical images to better diagnose patients. These can be under the surface of the skin and enable faster and more accurate diagnoses that can save people’s lives.
Recently, researchers have demonstrated how the industrial NDT method for inspecting electronic components in the manufacturing process using complementary metal-oxide-semiconductor (CMOS) sensors, could be applied to create highly accurate medical imaging (Martini et al., 2018). Applying the CMOS technology with a thin-film tungsten screen produced promising results for medical imaging, and this is a technique being actively pursued to produce medical imaging technology for the healthcare sector. The researchers argue that such a technique will advance medical imaging and enable earlier and more accurate diagnoses.
Another way NDT innovations have revolutionized medical imaging is in the development of echocardiography. This technique uses standard two-dimensional, three-dimensional, and Doppler ultrasound to produce an echocardiogram, or simply an echo. This has now become routine practice for cardiographers, who use the echo to find out information about patients’ hearts such as the size and shape of the heart, its pumping capacity, and the location and extent of any tissue damage. [PA1] This information can lead to early diagnoses of myocardial infarction or detection of cardiomyopathies (heart diseases).
Echocardiography was developed by Swedish physician Inge Edler (1911-2001) following breakthroughs in metal die-casting NDT by acoustical physicist Floyd Firestone (1898-1986). Similarly, NDT techniques originally developed for the industry have been applied in medical imaging to bring about the modern suite of diagnostic tools available to health practitioners.
For example, medical ultrasound – in which high-frequency sound waves are passed through the patient’s body, and their movement through the internal tissues measured to produce medical images – was developed by Austrian neurologist Karl Theo Dussik in partnership with his brother Friedreich Dussik, who was a physicist. The pair adapted ultrasound techniques first introduced to industrial processes to develop this life-saving medical imaging technology.
A more recent example of how NDT innovations have revolutionized medical imaging is in the development of digital radiography. This is a technique in which radiographic scans are immediately transferred to a connected computer, and is commonly used in dentistry to provide practitioners with real-time information about patients’ oral health. This example is different, however, as the medical imaging application was developed before being transferred to industrial applications.
In this way, NDT can be understood as a collaboration between researchers with widely different aims and objectives. This collaboration and interdisciplinary cooperation, and shared learning, only serves to progress both fields faster. While motivations for developing NDT methods can vary, the revolutionizing effects of new technology and techniques can be applied across different areas for the benefit of all – patients and industries alike.
- Martini, N., Koukou, V., Fountos, G., Valais, I., Bakas, A., Ninos, K., Kandarakis, I., Panayiotakis, G. and Michail, C. (2018). Towards the enhancement of medical imaging with non-destructive testing (NDT) CMOS sensors. Evaluation following IEC 62220-1-1:2015 international standard. Procedia Structural Integrity, 10, pp.326–332.