External Beam Radiation
External Beam Radiation Therapy (EBRT) can be used in conjunction with surgery, chemotherapy, brachytherapy and a variety of other techniques used in cancer treatment.
Various EBRT techniques can be used to deliver the radiation beams produced by a Linear accelerator (Linac) to the target. Among the newer treatment options for cancer of the prostate, brain,
lung, and head & neck are two methods of focusing radiation on the
tumor with its microenvironment and avoiding surrounding normal tissues:
a three-dimensional conformal radiation therapy (3-D RT) and intensity
modulated radiation therapy (IMRT). 3-D RT planning attempts to shape
the radiation fields as close as possible to the true tumor size and
shape, hence the term "Conformal".
3-D RT and IMRT methods both
use a CT image for general anatomic information and sometimes an MRI
and/or PET images for soft tissue detailed information of the patient to
perform the radiation dose calculations. An IMRT planning involves inverse radiation dose calculations and treatment delivery
optimization step. The most optimal IMRT plan is then delivered with a
computer-controlled Linac to conform or “paint” the
radiation dose very precisely matching the shape of the tumor and
avoiding critical structures that may be only millimeters away.
treatments are delivered with a varying or modulated radiation beam
intensity, hence the term “Intensity Modulated” radiation therapy. In
combination with advanced imaging techniques such as magnetic resonance
spectroscopy and positron emission tomography (PET) that image both tumor
anatomy and biology, IMRT holds great promise for improving local tumor
control and survival, even in the most resistant and aggressive human
Daily treatment sessions using EBRT usually only last 15 to 20 minutes; this includes both set-up (patient positioning) and treatment times. Treatments are usually given 5 days a week and last from 4 to 8 weeks.
See what to expect during your first appointment.