Radiotherapy,
one of the three pillars of cancer treatment [others including Chemotherapy and
Surgery] involves the utilization of ionizing radiations [X –rays /Gamma
Rays/Electrons/protons] for treating a variety of malignancies and also a few
benign disease like craniopharyngioma, Neurofibromatosis, etc.,
Evolution of Radiotherapy
Radiation
Oncology has evolved systematically and at the same time –by leaps and bounds
from the days of Radium;Cobalt 60; kilo voltage X-Rays to the era of linear
Accelerators /mega voltage X-rays and Iridium –192.
Fine- tuning of
the evolutionary accomplishments has resulted in high precision treatment
delivery.
Evolution of Technology
v
Conventional
Radiotherapy
Employs
treatment fields with regular, geometric dimensions [Square/rectangle, etc.]. However, this
was wrought with avoidable irradiation of normal tissues surrounding the tumor
areas resulting in:
a)
Under-dosing
of tumor areas
b)
Higher
normal tissue morbidity
v
3
D conformal RT
delivers
radiation to irregularly shaped fields –
conforming to tumor volume , while protecting normal tissues to some extent
with the aid of multi-leaf collimators
[MLC] of centimeter caliber
v
IMRT
With
the advent of advanced treatment planning software systems , which could process more complex planning algorithms ,
coupled with better image registration and machine up gradation-Intensity
Modulated Radiotherapy[IMRT]-revolutionized radiation oncology at the turn of
21st century.
The salient
advantages of IMRT are:
a)
CT
based slice –by slice planning
b)
Treatment
of concave target volumes
c)
Effective
dose limitation of organs at risk –eg:- Parotid/Rectum/Lung /Heart etc.,
d)
Millimetre
–level of precision of dose delivery-achieved with the aid of micro-multi leaf
collimators
e)
Higher
tumoricidal dose delivery thereby providing better therapeutic index.
v
Gating
Image
gated RT using 4D CT & Infra –red sensitive fiducials has found great use
in treatment of cancers in mobile organs -classically lung tumors.
v
Rapid
Arc
Ultrarapid
IMRT delivery with least possible intra fraction variation enbabled by state of
the art software.
Other recent advances include
a)
DART
[Dynamic adaptive RT]
b)
Tomotherapy
c)
True
Beam and
the list goes on & on…
By
Dr. Sathish Padmanabhan (MBBS, MDRT) has specialization in Radiation Oncology.
About MIMS Hospital:The Malabar institute of Medical sciences Ltd (MIMS), the first NABH Accredited multi specialty Hospital in India, is situated in the heart of Calicut (Kozhikode), Kerala, India. It is a pioneer hospital in India renowned for its excellent medical expertise, nursing care and quality of diagnostic services. For more details : Visit http://www.mimsindia.com
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