Webster's New World Medical Dictionary

radiation therapy, external
Radiation therapy in
which the source of radiation is a machine outside the
body.
radiation therapy, internal
Radiation therapy
in which a small container of radioactive material is
implanted in the body, in or near the cancerous
tumor.
radiation therapy, interstitial
A form of radio-
therapy in which tiny radioactive “seeds” are
implanted directly in the affected tissue with a nee-
dle-like instrument. Interstitial radiation therapy
has been used in the treatment of prostate and other
cancers.
radiation therapy, stereotactic
The use of a
number of precisely aimed beams of ionizing radia-
tion, each coming from a different direction and
meeting at a specific point, to deliver radiation treat-
ment to that spot.
radical, free
See 
free radical.
radical dissection
Surgical removal of not only
affected tissue, but also nearby tissue that may be
covertly affected.
radical mastectomy
See 
mastectomy, radical.
radical neck dissection
Often called a “radical
neck,” a surgical procedure that involves the
removal of a tumor from the neck with an additional
margin of seemingly normal tissue of at least 2 cm
together with the removal of the lymph nodes from
the neck.
radiculitis
See 
radiculopathy.
radiculopathy
Any disease of the spinal nerve
roots and spinal nerves. Radiculopathy is character-
ized by pain that seems to radiate from the spine,
extending outward to cause symptoms away from
the source of the spinal nerve root irritation. Causes
of radiculopathy include deformities of the discs
between the vertebrae. Patients with diabetes can be
affected by a form of radiculopathy that may be
caused by inadequate blood supply to the spinal
nerve roots. Also known as radiculitis.
radioactive
Emitting energy waves due to decay-
ing atomic nuclei. Radioactive substances are used
in medicine as tracers for diagnosis and in treat-
ment to kill cancerous cells.