Advances in radiation therapy
Innovative techniques harness advances in computer imaging, satellite technology, and particle physics.
Radiation oncology is one of the most
sophisticated and quickly evolving
areas of medicine. From computer-assisted
techniques to the application
of particle physics, innovations in
radiation therapy have the ability
to precisely target the site
of the cancer while sparing
surrounding healthy tissue.
Your radiation team
Your radiation team includes a
number of highly trained doctors,
specialists, and caregivers who work
with you throughout your treatment:
The radiation
oncologist is
a doctor who
specializes in
treating cancer
with radiation
therapy, and who
will determine
and oversee
your treatment
The radiation physicist helps
the radiation
oncologist
design and
implement
treatment and
ensures proper
functioning of
equipment
The dosimetrist helps the radiation
oncologist
formulate
treatment and
determine techniques
such as
angle of radiation
entry and daily
radiation dose
The radiation
therapist operates the
equipment
and positions
you for
treatment
The radiation
therapy nurse has extensive
experience
working with
people who are
undergoing
radiation
treatment
State-of-the-art medicine
Intensity modulated
radiation therapy (IMRT)
is an important breakthrough
in external
radiation and effective
in the treatment of
difficult-to-reach cancers,
and those located close
to delicate organs. Using
a computer program,
the oncologist can plan
a precise dose of radiation
in three dimensions,
based on the size, shape,
and location of the tumor.
IMRT delivers radiation
in thousands of thin beams that enter
the body from
hundreds
of angles, intersecting
the
cancer with
great precision.
Another
high-technology
approach is 3D conformal radiation.
Using three-dimensional computer
mapping, the oncologist produces an
accurate image of the
tumor and surrounding
organs, so that multiple
radiation beams can be
shaped exactly to the
contour of the tumor.
Advanced imaging technology
has opened the door to a variety
of other highly targeted methods
for treating cancer. For example,
TheraSphere® is an advanced technique
that specifically targets tumors
in the liver by using microscopic glass
beads to deliver radiation.
Using an angiogram, or X-ray of
the blood vessels surrounding the
liver, doctors select the artery through
which they can deliver the beads.
Then, using a technique called X-ray fluoroscopy,
which allows them to see
a live image of the body, doctors guide
a catheter containing the beads to the
proper place in the liver.
The beads, which contain the
radioactive substance Yttrium-90, are
the right size to lodge in the blood
vessels associated with the cancerous
tissue but not in the blood vessels of
the healthy parts of the liver.
Proton therapy
One of the most significant advances
in radiation therapy is proton therapy.
Protons — or positively charged elementary particles found in the nuclei
of all atoms — are extracted from
hydrogen atoms and directed at the
tumor using magnetic fields.
Unlike X-rays, protons emit a very
high dose of radiation but scatter
very little. These properties enable
oncologists to deliver an extremely
aggressive yet precise radiation dose
to the tumor.
Proton therapy has proven remarkably
effective in the treatment of many
cancers, including lung, brain, and
prostate cancers. However the size
and cost of the equipment, which can
weigh 900 tons and require an investment
of $175 million or more, has
so far limited the treatments to a few
facilities in the United States. Proton
beam treatment will likely become
more common as additional facilities
are built in coming years.
Tumor tracking
The effectiveness of radiation treatments
depends in many cases on the
ability to pinpoint the exact location
of the tumor. But a challenge that
doctors face is that many organs,
glands, and other human tissue
constantly shift slightly in the body.
That means that during treatment,
doctors often end up radiating large
margins, or borders, of healthy tissue
to make sure they target the entire
cancerous area.
One innovative solution to this
problem is a small wireless device
akin to a global positioning system
(GPS) that doctors can implant in
the tumor to track its precise position
in real time. Called the Calypso® 4D
Localization System™, the technology
is now being used in the treatment of
prostate cancer.
High-dose rate brachytherapy (HDR)
In this innovative approach to
brachytherapy, computers are used to
deliver a few concentrated doses of
radiation over a few short outpatient
treatments. Each HDR session lasts
only ten to twenty minutes over one to
five days of treatment. That’s far less
time than external radiation therapy,
which takes six to eight weeks. Plus,
HDR poses very little risk of radiation
injury to the rest of your body.
MammoSite® radiation therapy (MRT) is used after a lumpectomy, or the
surgical removal of a breast tumor to
prevent a recurrence. The oncologist
inserts a small, balloon-shaped catheter
into the cavity where the tissue
was removed. Then the oncologist
loads the catheter with a radioactive
pellet. You can receive treatment as
an outpatient, usually over one to five
days. MRT is far less invasive than
external radiation, and can help doctors
preserve as much of the healthy
breast tissue
as possible.