The goal of radiation therapy is to damage cancer cells, with as little
harm as possible to nearby healthy cells. Radiation kills cancer cells
chiefly by damaging their DNA (large molecules inside cells that control
the cell’s function and carry genetic information from one generation
to the next).
Radiation therapy uses high-energy radiation to shrink tumors and kill
cancer cells. X-rays, gamma rays, and charged particles are types of radiation
used for cancer treatment. The radiation may be delivered by a machine
outside the body (external-beam radiation therapy), or it may come from
a small x-ray machine or radioactive material placed in the body near
cancer cells (internal radiation therapy, also called brachytherapy).
During Treatment
Radiation therapy is painless. You will not feel anything out of the ordinary
during treatment but you will hear a buzzing sound. Our team monitors
you throughout treatment, and they can pause treatment at any time to
provide assistance.
External-Beam Radiation therapy administers a broad beam of radiation from
one or several directions for each treatment. It delivers low-dose beams
of radiation from a few, up to 45 treatments - the intervals between each
treatment allow healthy tissue, damaged during treatment, to recover.
3-Dimensional Conformal Radiation Therapy (3D-CRT): One of the most common
types of external-beam radiation therapy is called 3-dimensional conformal
radiation therapy (3D-CRT). 3D-CRT uses sophisticated computer software
and advanced treatment machines to deliver radiation to very precisely
shaped target areas.
Intensity Modulated Radiation Therapy (IMRT): Some patients benefit from
a more highly focused and shaped external beam therapy called Intensity
Modulated Radiation Therapy (IMRT). The goal of IMRT is to increase the
radiation dose to the areas that need it and reduce radiation exposure
to specific sensitive areas of surrounding normal tissue. Your Radiation
Oncologist will determine if IMRT is appropriate for you.
Image-guided radiation therapy (IGRT): In IGRT, x-ray images are taken
immediately before each daily treatment is delivered and the patient position
is adjusted using internal anatomy to make sure the treatment is on-target.
These images are used by the therapists (the staff that delivers your
treatment each day) to adjust your position so you receive precisely the
treatment your doctor has ordered.
Radiosurgery
Radiosurgery uses small beams of radiation very accurately targeted to
the tumor. The small size of the beams and their arrangement allow a high
dose to be accurately placed on a tumor, with a sharp fall-off of dose
outside the tumor. Because very little of the surrounding normal tissue
is treated, very large doses can be given to the tumor, typically in one
or a few sessions.
CyberKnife is a form of robotic radiosurgery designed to treat tumors anywhere
in the body with pinpoint, sub-millimeter accuracy. With radiosurgery,
damage to surrounding healthy tissue is minimized; therefore, the treatment
can be completed in 1 to 5 days. Targets that move, such as a lung tumor
that moves with breathing, can also be tracked throughout the treatment.
Despite its name, there is no surgery involved.
Internal radiation therapy (brachytherapy) is radiation delivered from
radiation sources (radioactive materials or tiny x-ray machines) placed
inside or on the body. Permanent interstitial brachytherapy uses radiation
sources about the thickness of a pencil lead placed within tumor tissue,
such as within a prostate tumor. The sources are surgically sealed within
the body and left there, even after all of the radiation has been given
off. The remaining material (in which the radioactive isotopes were sealed)
does not cause any discomfort or harm to the patient.
