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32.1 Medical Imaging and Diagnostics
Two people were caught entering the United States from Canada.
Nuclear radiation is used in a number of medical techniques.
It is a useful probe to monitor conditions inside the body because radiation can easily penetrate tissue.
Nuclear radiation depends on the nuclide and not on the chemical compound it is in, so that a radioactive nuclide can be put into a compound designed for specific purposes.
The location and concentration of a radiopharmaceutical can be determined by radiation detectors outside of the body.
Another application uses a radiopharmaceutical that the body sends to bone cells to detect tumors or healing points.
Images can be produced from bone scans.
Radioisotopes can be used to determine the functioning of body organs, such as blood flow and heart muscle activity.
A radiopharmaceutical is used to produce a brain image.
The features are computer enhanced.
Table 32.1 lists certain uses of radiopharmaceuticals.
Many organs can be imaged with a variety of nuclear isotopes.
Isidore is used to image the thyroid, since it is concentrated in that organ.
The most active cancer cells concentrate the most iodine and emit the most radiation.
Hypothyroidism is indicated by lack of iodine.
There are more than one isotope that can be used for multiple types of scans.
The thallium scans are used to evaluate the cardiovascular system and look at heart activity.
The salt is similar to NaCl and can be used.
There is rapid cell growth where Gallium-67 accumulates.
It's useful in cancer scans.
It can take several days for the gallium to build up after the injection, so it's best to have a body Scan 3 or 4 days after the injection.
There are many diagnostic uses for radiopharmaceuticals, where "m" stands for a metastable state of the technetium nucleus.
80% of radiopharmaceutical procedures use it because of its many advantages.
The decay of its metastable state produces a single, easily identified 0.142-MeV ray.
The radiation dose to the patient is limited by the short half-life.
Its half-life is short, but it is easy to produce on site.
The basic process for production is.
A piece of lead with holes bored through itcollimates rays emerging from the patient, allowing detectors to receive rays from specific directions only.
An image is produced by the computer analysis of detector signals.
One of the disadvantages of this method is that it doesn't give a depth view of the tumor, because radiation from any location under that detector produces a signal.
An Anger camera has a lead collimator and an array of detectors.
There are light flashes in the scintillators.
The photomultipliers convert the light output to an electrical signal.
A computer creates an image.
Nuclear activity in patients is used to form threedimensional images in x-ray computed tomography (CT) scans.
The spatial resolution is poor, about 1 cm.
The difference in visual properties that make an object different from other objects is good.
An image of the concentration of a radiopharmaceutical compound is created by SPECT using a geometry similar to aCT.
In recent years, images produced by emitters have become important.
Two rays are produced when the emitted positron encounters an electron.
It requires detectors on opposite sides to detect the same photon at the same time.
The advantage of this list is that they can be used as tags for natural body compounds.
The accuracy and sensitivity of the scans make them useful for examining the brain's function.
The brain's use of oxygen and water can be monitored.
It is used to diagnose brain disorders.
A confirmation of Alzheimer's disease can cause decreased metabolism in certain regions.
When a person carries out specific activities, such as speaking, closing their eyes, and so on, the brain can become active.
The two identical -ray photons produced by positron-electron annihilation are used in a PET system.
The line along which each pair is emitted is determined by the rays that are emitted in opposite directions.
The events detected by several pairs of detectors are analyzed by a computer to create an accurate image.
MRI can tell.
Nuclear spins of the hydrogen nuclei of your water molecule are what radio transmitters are made of.
These little radios can be made to broadcast their positions, giving a detailed picture of the inside of your head.
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