There are two major uses
• Radiology largely uses lower-energy radiation to
of ionizing radiation in
the diagnosis and
treatment of cancer:
• Radiotherapy, or radiation
therapy, uses high-energy
radiation to control and eliminate cancer.
image tissues to diagnose disease or treat disease
via the minimally invasive techniques used in
Radiotherapy is the use of high-energy rays (e.g., gamma rays and
X-rays) or particles (e.g., electrons,
protons, and carbon nuclei) to
control or eliminate cancer.
Radiotherapy works chiefly
by damaging DNA, leading
to cell death.
Curative radiotherapy seeks to completely eliminate a cancer,
particularly small cancers, as well as locally advanced cancers
as part of combination therapy.
Neoadjuvant radiotherapy is used to reduce or control a cancer so that
it can be subsequently treated by a different method such as surgery.
Adjuvant radiotherapy seeks to eliminate any remaining cancer following prior treatment.
Palliative radiotherapy is used to reduce or control symptoms of disease when cure by another method is not possible.
Particle therapy uses protons or
Brachytherapy places small radioactive
carbon ions rather than X-rays as
the source of energy. In contrast
to X-rays that pass though the
body, losing energy and causing
damage to the noncancerous
tissues through which they pass, these heavier
particles deposit most of their energy in the target. In
this manner, particle therapy can deliver higher doses
with less damage to surrounding tissue. Although
of great interest, proton facilities are much more
expensive than traditional facilities and the overall
benefit to the patient is still being determined.
sources in or next to the tumor either
temporarily or permanently.
External beam radiotherapy encompasses several
types of radiotherapy that direct radiation
at the tumor from outside the body; it is
the most common form of radiotherapy.
Electrons and photons (X-rays)
are the most common sources
of radiation in external
Radioisotope therapy involves systemic
ingestion or infusion of radioisotopes,
for example, iodine-131 to treat thyroid
cancer or yttrium- 90 ibritumomab
(Zevalin) to treat non-Hodgkin lymphoma.
Using Radiation in Cancer Care
Adapted from ( 25)
USES OF RADIOTHERAPY
TYPES OF RADIOTHERAPY