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Radiotherapy
Radiotherapy is the
main stay of treatment for most of the solid tumors. About 70%-80%
of patients require radiotherapy either alone or in combination with
surgery and /or chemotherapy. Radiotherapy may be curative, adjuvant
and palliative.
 The medical
Linear Accelerator produces higher-energy x-rays that
can penetrate deeper into tissue and reduce dose to skin. The linear
accelerator uses high-frequency electromagnetic waves to accelerate
electrons to high energy through a microwave accelerator structure.
The high-energy electron beam itself can be used for treating
superficial tumors or it can be made to strike a target to produce
an x-ray beam for treating deep-seated tumors.
The Multileaf collimator facilities the use of complex
three-dimensional treatment plans. The Multileaf collimator contains
multiple pairs of thin leaves (usually 20 to 40) that attenuate the
beam. Since each leaf can be moved independently of the others, a
field of any shape can be rapidly created eliminating the time
required to reenter the treatment room and insert customized
beam-shaping blocks.
Three-dimensional (3-D) conformal radiation therapy.
Traditionally , the
planning of radiation treatments has been done in two dimensions
(3-d) conformal radiation therapy uses computer technology to allow
doctors to more precisely target a tumor with radiation beams (using
width, height, and depth). Many radiation oncologists use this
technique. A 3-D image of a tumor can be obtained using computed
tomography (CT), magnetic resonance imaging (MRI), positron emission
tomography (PET), or single photon emission computed tomography (SPECT).
Using information from the image, special computer programs design
radiation beams that �conform� to the shape of the tumor. Because
the healthy tissue surrounding the tumor is largely spared by this
technique, higher doses of radiation can be used to treat the
cancer. Improved outcomes with 3-D conformal radiation therapy have
been reported for nasopharyngeal, prostate, lung, liver, and brain
cancers.
Intensity- modulated radiation therapy (IMRT).
IMRT is a new type of
3-D conformal radiation therapy that uses radiation beams (usually
x-rays) of varying intensities to deliver different doses of
radiation to small areas of tissue at the same time. The technology
allows for the delivery of higher doses of radiation within the
tumor and lower doses to nearby healthy tissue. Some techniques
deliver a higher dose of radiation to the patient each day,
potentially shortening the overall treatment time and improving the
success of the treatment. IMRT may also lead to fewer side effects
during treatment.
The radiation is delivered by a linear accelerator that is equipped
with a multileaf collimator (a collimator helps to shape the beams
of radiation). The equipment can be rotated around the patient so
that radiation beams can be sent from the best angels. The beams
conform as closely as possible to the shape of the tumor. Because
IMRT equipment is highly specialized, not every radiation oncology
center uses IMRT.
CT Simulator with integrated 3D Treatment Planning System)
Hemalata Hospitals and Research Centre, Bhubaneswar has the proud
privilege of installing India's first integrated CT Simulator with
3D treatment planning system, that was inaugurated by Dr.APJ Abdul
Kalam., president of India on the 27th December 2005.
Once it is decided that the patient is to be given Radiotherapy, the
first job is to simulate the treatment by the CT simulator and then
the treatment is planned with the 3D treatment planning system. CT
simulation is done by positioning the patient in exactly the same
condition in which the treatment will be delivered in the Linear
Accelerator. The process gives a digital model of the patient with
the tumor and other critical structures marked by the specialists.
Then the treatment planning system uses the machine parameters to
optimally plan the treatment and transfers the final and approve
plan to the Linear Accelerator computer which delivers the
treatment.
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