Category: E

Delivery of a baby when no medical help is available. Emergency childbirth is sometimes needed when access to medical help is blocked, or when the labor is proceeding faster than expected. Childbirth is a natural process that should normally proceed without interference, and bystanders should intervene only when necessary. It is never advisable to try…

Subtraction of two digitized x-ray images which were produced by x rays whose energies were different.  

A form of tomography in which the emitted decay products (such as positrons or gamma rays) of an ingested radioactive pharmaceutical are recorded in detectors outside the body. Computer reconstruction of the data yields a cross-sectional image of the body.  

Techniques for producing radiographic images in which the ionic charge liberated during the irradiation process is converted to a visible image using electronic read-out devices or by the use of liquid or powder “toner” to convert a latent charge image into a visible one.  

A unit of energy, first used in accelerator physics, equal to the energy acquired by an electron in falling through a potential difference of one volt. One eV equals 1.6X10 -12 erg or 1.6 X 10-19 J. The energy acquired by an electron as it passes through a potential of 1 V.  

A radioactive decay process in which a nucleus with an excess of electrons brings one of them into the nucleus, creating a neutron out of a proton, thus decreasing the atomic number of the atom by 1 . The resulting atom is often unstable and gives off a gamma ray to achieve stability.  

Radiation in the form of waves or, equivalently, in the form of photons. In order of increasing energy (decreasing wavelength) the principal parts of the electromagnetic spectrum are radio waves, microwaves, infrared, visible, ultraviolet (uv), x ray, and gamma ray. Rays that travel at the speed of light. They exhibit both magnetic and electrical properties.…

The production in tissue of electric fields and associated eddy currents by time-varying magnetic fields produced by coils. Generation of an electromotive force, in an insulated conductor moving in an electromagnetic field, or in a fixed conductor in a moving magnetic field.  

A procedure in which a doctor attempts to reposition a fetus in the uterus to avoid a breech delivery by applying slow, steady pressure to the pregnant woman’s abdomen. If a fetus is in a breech presentation (buttocks or feet first instead of head first) after the 36th week of pregnancy, external version may be…

Noncancerous swelling of the prostate gland. An enlarged prostate is also known as benign prostatic hyperplasia (BPH), which is usually a result of aging. Benign prostatic hyperplasia develops first in the portion of the prostate surrounding the urethra, narrowing this urinary passage. Signs include slowed or delayed start of urination, a weak urine stream, pain…