IMRT
Intensity modulated radiation therapy is a relatively new way to
deliver radiation treatments. It is a dramatic advancement that
allows the radiation oncologist to give higher doses to the tumor
while sparing as much normal tissue as possible.
Its benefits include:
- Delivering higher doses to the tumor with fewer side effects
and risks to nearby organs.
- The
improvement in salivary function in the head and neck cancer
patient who requires treatment.
- Retreatment
of some areas previously untreatable.
- Improvement
of quality of life by reducing pain.
The type of radiation delivered by the linear accelerator
(treatment machine) is the same as had been used for
decades. What
makes IMRT different is the combination of two new pieces of equipment.
The first is the movable shielding devices within
the head
of the
treatment machine called multi-leaf collimators (MLC). Our top-of –the –line
machines contain 120 individual leaves each controlled
by its own motor. These motors are computer-controlled and can
drive the leaf
at different speeds across the treatment field.
The second advancement is a computer driven process
called “inverse planning.” In
this process, the doctor draws on the CT image and tells the
dosimetrist how much dose to give the tumor and
what normal tissue to protect. The dosimetrist
runs the computer that will use this information to calculate
the best plan. The physicist does quality checks
on the treatment fields to double check for
accuracy. The doctor reviews the plan to finalize it before
the first treatment is given.
The goal for most patients having IMRT is to improve cure rates
and reduce side effects. This may result in the individual having
not
only the best
chance for
cure, but in many cases, the best quality of life.
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