What is Radiation Therapy
Radiation therapy, or radiotherapy, uses ionizing radiation produced by
a linear accelerator (linac) to destroy cancer cells and shrink tumors.
The radiation passes through the body and delivers dose to the affected
area while minimizing dose to the skin and tissue it passes through.
Although the radiation affects both cancer and normal cells, it has a greater
effect on the cancer cells, damaging their genetic material and making
impossible for these cells to continue to grow and divide. Treatment aimed
at cure will give the highest possible dose of radiation to the cancer
area (within safe limits) to attempt to destroy all the cancer cells.
Sometimes smaller doses are used, where the aim is to reduce the size
of a tumor and/or relieve symptoms.
Most patients undergo radiation therapy once a day, five days per week,
over a period lasting from two to ten weeks. The total time, beginning
with your first and ending with your last session, is called a course
of treatment. Some patients are prescribed
hypofractionated radiation therapy, which delivers higher doses of radiation in a more
targeted fashion over fewer treatments.
Electrons are used to treat skin cancers and other superficial lesions,
as they are absorbed by the first few centimeters of skin, leaving very
little dose to pass into the body. Radiation therapy is used to both cure
disease and alleviate the symptoms of cancer. There are also a number
of non-malignant conditions that are treated using radiation therapy.
What happens during Radiation Therapy
Here are the steps you’ll go through at
Flagler Radiation Oncology Center
The radiation oncologist may ask for diagnostic procedures to be undertaken,
either in the radiation therapy department or at a general hospital. These
can include x-rays, computed tomography (CT), magnetic resonance imaging
(MRI), positron emission tomography (PET) scans, biopsies and blood tests.
Once the nature of the disease has been established, a treatment regime
will be planned and prescribed.
MRI, CT or PET scanning, or ultrasound is required to determine the exact
size, shape and position of the area to be treated within the body, known
as the treatment site. These images are then used to plan the patients’
treatment. You are positioned exactly as you will be for your treatments,
which may involve the use of immobilization devices to help you keep still.
Marks are made on your skin to indicate the treatment area. Once you are
positioned, images are acquired to help your treatment team plan as precise
a treatment as possible while reducing the impact on organs and critical
3. Treatment Planning
Once your images have been taken your physician prescribes the appropriate
total dose of radiation and over how many days your treatment is to be
administered, considering the tumor target and critical structures in
the treatment area. Your physicist and dosimetrist work closely with your
radiation oncologist and use sophisticated software to calculate the position,
dose and frequency of the series of radiation beams that are to be your
treatment. Before treatment commences the treatment may be simulated –
i.e., performed on a non-treating machine, to ensure the correct treatment
will be delivered later.
4. Delivery (treatment)
Treatment may be given on an out-patient or in-patient basis. It is imperative
that the prescription and treatment plan is adhered to as any missed treatment
may affect success. The patient usually receives the same treatment each
day for a course of treatment, which can last up to six weeks. Treatment
is monitored regularly and may be adjusted if the patient suffers from
adverse side effects or loses weight.
To receive the radiation therapy, you will lie on a couch under the machine,
and be asked to remain still during the actual treatment. Once all is
ready, your radiation therapist leaves the room to monitor your treatment.
The gantry of the linear accelerator begins to rotate around you, as you
breathe normally. You may see and hear this movement, but the treatment
is completely painless. Radiation cannot be seen or felt while it is being given.
During treatment a process of verification takes place. By using built-in
imaging on Versa HD, images are taken of the treatment site. These images
are used to verify both the patient position and the accuracy of the treatment beam.
Once your course of treatment is completed, you attend follow-up clinics
for up to five years, to monitor your disease and manage any post-treatment
side effects. Initially you will come to our center. Annual follow-ups
may then be conducted by the specialist who sent you to for treatment.