Metrology Careers Blog

Careers in measurement science.

Modern Marvels – Medical Scanning 02/08/2011

Filed under: Modern Marvels — admin @ 1:58 pm

Infrared thermometry is widely used in many industries. The standard of calibration for infrared thermal measurement is called a black body. A black body is an idealized physical body that absorbs electromagnetic radiation. Because of this perfect absorptivity at all wavelengths, a black body is also the best possible emitter of thermal radiation, which it radiates incandescently in a characteristic, continuous spectrum that depends on the body”s temperature. The object appears black, since it does not reflect or emit any visible light.

The development of medical thermal scanning technologies has also found applications in the areas of fire fighting, maintenance of mechanical equipment, as well as any facility dependent on well controlled temperatures.

Other examples of technologies impacted by the field of metrology include incredibly detailed x-ray capabilities allowing doctors to effectively diagnose illness which plays a critical role in the future of healthcare. Many medical scanning technologies emit different types of radiation as part of the way they determine critical measurements. The average annual radiation exposure from just medical diagnostics is about 310 millirem per person. Yet this is only 5 0% of the expected annual exposure per person. Normal and safe amounts of expected radiation come from a variety of sources. Did you know that a person flying in an airplane can receive more radiation than someone who lives near a nuclear plant? Flying in an airplane reduces the atmospheric shielding from the sun and cosmic radiation. You receive about 1 millirem of radiation for each 1,609.344 km you fly. Conversely, people living near a nuclear power plant only receive 0.009 millirem per year.

An MRI machine uses a powerful magnetic field to align the magnetization of some atoms in the body, and radio frequency fields to systematically alter the alignment of this magnetization This causes body cell nuclei to produce a rotating magnetic field detectable by the scanner—and this information is recorded to construct an image of the scanned area of the body. A typical scanner has a magnetic field strength of 3 teslas (T) or about 50,000 times greater than the Earth’s field.


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