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Positron emission tomography (PET) [1] is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging ...
For gamma radiation this is numerically equivalent to equivalent dose measured by the sievert, which indicates the stochastic biological effect of low levels of radiation on human tissue. The radiation weighting conversion factor from absorbed dose to equivalent dose is 1 for gamma, whereas alpha particles have a factor of 20, reflecting their ...
Ionizing radiation (US, ionising radiation in the UK), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. [1] Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high ...
Collimator used to collimate gamma rays (red arrows) in a gamma camera. Single-photon emission computed tomography (SPECT, or less commonly, SPET) is a nuclear medicine tomographic imaging technique using gamma rays. [1] It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, scintigraphy), [2] but is ...
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiography and "therapeutic") and industrial radiography. Similar techniques are used in airport security, (where "body scanners ...
Dose equivalent calculates the effect of radiation on human tissue. [4] This is done using tissue weighting factor, which takes into account how each tissue in the body has different sensitivity to radiation. [4] The effective dose is the risk of radiation averaged over the entire body. [4] Ionizing radiation is known to cause cancer in humans. [4]
The field strength of electromagnetic radiation is measured in volts per meter (V/m). [2]: 139. The most common health hazard of radiation is sunburn, which causes between approximately 100,000 and 1 million new skin cancers annually in the United States. [3][4] In 2011, the World Health Organization (WHO) and the International Agency for ...
The radioactive gamma rays are emitted through the body as the natural decaying process of these isotopes takes place. The emissions of the gamma rays are captured by detectors that surround the body. This essentially means that the human is now the source of the radioactivity, rather than the medical imaging devices such as X-ray or CT.