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This much-used symbol has many meanings in medicine. They include: 1) Respiration: a nurse's note of "R20" is shorthand for 20 respirations (breaths) per minute. 2) Right: A doctor's note of a burn on the "R digit 5" places the burn on the right little finger or toe. 3) Roentgen. 4) In chemistry, a radical. 5) On a prescription, R (or Rx), recipe, which is Latin for "to take".

A potentially fatal viral infection that attacks the central nervous system. Rabies is carried by wild animals (particularly bats and racoons), and finds its way to humans either by direct contact, or by contact with domestic animals that have contracted the virus. Most cases can be traced to animal bites, but cases have been documented where the virus was inhaled in bat caves, contracted in lab accidents, or received from transplanted donor tissue. Symptoms include fever, aching muscles, and headache, potentially progressing to inflammation of the brain, confusion, seizures, paralysis, coma, and death. There is no cure for rabies once it has settled in the brain, so immediate emergency care for any suspicious animal contact is a must. Rabies immunoglobulin (RIG) shots, antibiotics, and rabies vaccine may be used immediately after contact. To prevent rabies, vaccinate all pets against the virus, and avoid contact with wild or unknown animals. A human rabies vaccine is available, but is recommended only for those in high-risk occupations (game wardens, zookeepers, animal control officers, etc.)

A descriptive term for something that is in a cluster or bunch.

From the Latin “racemus” meaning “a cluster or bunch, particularly of grapes.”

Racemose aneurysm
An aneurysm that looks like a bunch of grapes.

Radiation absorbed dose, a measure for a dose of ionizing radiation.

To spread out from a central area. For example, sciatic pain may radiate outward from the lower back.

1) Rays of energy. Gamma rays and X- rays are two types of energy waves often used in medicine. 2) The use of energy waves to diagnose or treat disease.

Radiation fibrosis
Scarring of the lungs from radiation.

Radiation fibrosis is a sequel of radiation pneumonitis (inflammation of the lungs due to radiation), as from radiation therapy. Radiation preumonitis typically occurs after radiation treatments for cancer within the chest or breast and usually manifests itself 2 weeks to 6 months after completion of radiation therapy. Symptoms include shortness of breath upon activity, cough and fever. Radiation pneumonitis frequently is discovered as an incidental finding on chest x-ray in patients who have no symptoms.

Scarring of the lungs with radiation fibrosis is an aftermath of persistant radiation pneumonitis. Radiation fibrosis typically occurs a year after the completion of radiation treatments.

Whereas radiation pneumonitis is often reversible with medications that reduce inflammation, such as cortisone drugs (prednisone and others), radiation fibrosis is usually irreversible and permanent.

Radiation menopause
Menopause induced by radiation.

Radiation menopause is a type of "induced menopause", menopause induced by an unusual event, such as occurs when the ovaries are damaged by radiation, chemotherapy or other medications; or as occurs when the ovaries are surgically removed (by bilateral oophorectomy).

Induced menopause, radiation menopause included, is distinct from natural menopause which occurs when the ovaries naturally decrease their production of the sex hormones estrogen and progesterone; there are no menstrual periods for 12 consecutive months; and no other biological or physiological cause can account for this phenomenon. Menopause is the end of the childbearing years, the finale of fertility. (The basis for the "12 consecutive months" criterion for menopause is that, until 12 months have passed without a period, a woman may still become pregnant).

Induced menopause, due to the abrupt cutoff of ovarian hormones, causes the sudden onset of hot flashes and other menopause-related symptoms such as a dry vagina and a decline in sex drive. Early menopause (before age 40)carries a greater risk for heart disease and osteoporosis since there are more years spent beyond the protective cover of estrogen.

When the levels of hormones normally produced by the ovaries suddenly drop, changes associated with the menopause promptly take place: hot flashes (a sudden warm feeling with blushing), night sweats, mood swings, vaginal dryness, fluctuations in sexual desire (libido), forgetfulness, trouble sleeping and fatigue, probably from loss of sleep.

Estrogen replacement therapy (ERT) may be used to treat induced menopause. It reduces or stops the short-term changes of menopause such as hot flashes, disturbed sleep, and vaginal dryness. ERT can prevent osteoporosis, a consequence of lowered estrogen levels. To keep bones strong, ERT should be taken from menopause throughout a woman's life. Stopping ERT allows bone loss to resume.

ERT reduces the risk of heart disease up to 50%. Vaginal ERT products help with vaginal dryness, more severe vaginal changes, and bladder effects but, since very little vaginal estrogen enters the circulation, it may not help with hot flashes or prevent osteoporosis and heart disease.

The use of unopposed ERT (ERT alone) is associated with an increase in the risk of endometrial cancer (cancer of the lining of the uterus). However, by taking the hormone progestogen along with estrogen, the risk of endometrial cancer is reduced substantially. Progestogen protects the uterus by keeping the endometrium from thickening (an effect caused by estrogen). The combination therapy of estrogen plus progestogen is called hormone replacement therapy (HRT).

Radiation oncologist
A specialist in the use of radiation therapy as a treatment for cancer.