This document provides an overview of various radiotherapy techniques used to treat cancer. It describes teletherapy which uses external beams of radiation from radioactive sources like cobalt-60 or iridium-192. Common teletherapy techniques discussed include 2D conformal radiation therapy (2DCRT), 3D conformal radiation therapy (3DCRT), intensity modulated radiation therapy (IMRT), image guided radiation therapy (IGRT), volumetric modulated arc therapy (VMAT), stereotactic body radiation therapy (SBRT), and stereotactic radiosurgery (SRS). Each technique is explained in one or two sentences along with examples of imaging technologies and treatment machines used.

1. RT Subhankar Kar
RT Sanu Majumder

2. Contents
 Radiotherapy
 Teletherapy
 Teletherapy techniques
 2DCRT
 3DCRT
 IMRT
 IGRT
 VMAT
 SBRT
 SRS

3. Radiotherapy
 Radiation therapy or Radiotherapy is a type of cancer
treatment that uses high ionizing radiation doses to kill the
cancer cells and shrink tumours.
 Radiation therapy can be delivered by two types of
processes 
i. Brachytherapy
ii. Teletherapy

4. Teletherapy
 Teletherapy is the production of an external beam of gamma
rays for the treatment cancer patients at a distance from the
radioactive source.
 Radioactive sources that have been used for teletherapy are
Co–60, Ir–192, Cs–137 etc.
 Teletherapy treatment is useful for the treatment of cancers
of head and neck area, ca–breast, ca–lung etc.

5. Teletherapy Techniques
 Nowadays different types of teletherapy treatment
techniques have been used in radiotherapy; such as 
i. 2DCRT
ii. 3DCRT
iii. IMRT
iv. IGRT
v. VMAT
vi. SBRT
vii. SRS

6. 2DCRT
 Two dimensional conventional radiation therapy (2DCRT)
refers to the old techniques of radiation therapy where
treatments would be planned by defining a limited number of
beams with the boundaries delineated on orthogonal X–rays
of the patients.
 Beam shaping was limited and typically simple square or
rectangular beams were used.
 Although 2D radiotherapy is now rarely used, it still has a
role in palliative treatment.

7. 2DCRT
 2DCRT treatment can be delivered by using Phoenix
machine, Bhabhatron and LINAC machine.
2D image of cranial tumour

8. 3DCRT
 Three dimensional conformal radiation therapy (3DCRT)
is an advanced technique that incorporates the use of
imaging technologies to generate 3D images of patient’s
tumour and nearby organs and tissues.
 The goal of 3DCRT is to deliver a conformal dose
distribution to tumours, while sparing the surrounding
normal structures.
 It allows for a high level of precision and accuracy in the
delivery of radiation treatment.

9. 3DCRT
 In 3DCRT, the 3D images can be produced by following
imaging modalities 
 Computed tomography (CT)
 Magnetic resonance Imaging (MRI)
 Positron emission tomography (PET)
 PET–CT
Field view of
3DCRT cervix
cancer

10. IMRT
 Intensity modulated radiation therapy (IMRT) is an
advanced mode of high-precision radiotherapy that uses
computer controlled linear accelerators to deliver radiation
doses to a malignant tumour.
 IMRT allows for the radiation dose to conform more
precisely to the 3D shape of the tumour by modulating of
controlling the intensity of the radiation beam.
 Treatment is carefully planned by using 3D CT or MRI
images of the patient.

11. IMRT
 By using IMRT higher and more effective radiation doses
can safely be delivered to tumours with fewer side effects
compared with conventional radiotherapy.
Comparison between 2DCRT, 3DCRT and IMRT

12. IGRT
 Image guided radiation therapy (IGRT) is a type of cancer
treatment that employs imaging technologies like PET, MRI
and CT to deliver radiation to cancer cells more precisely and
safely.
 IGRT is used to treat all types of cancer but it is particularly
ideal for tumours located very close to sensitive structures
and organs.
 It is also used to treat tumours in areas of the body that are
prone to movement such as lungs, liver, prostate etc.

13. IGRT
 The main benefit of IGRT is that it can 
i. Kill the malignancy, using larger doses of radiation.
ii. Prevent causing damage to surrounding healthy tissue.
iii. Minimize the radiation side effects.
CT is equipped with
LINAC

14. VMAT
 Volumetric modulated arc therapy (VMAT) is a radiation
therapy technique in which radiation beam continuously
rotates isocentrically around the patient.
 In this technique one or more sectors of a 360 rotation are
skipped to reduce the dose to critical normal structures.
 It is suitable for small, symmetric, deep seated tumours and
usually limited to field sizes less than approximately 10 cm in
width for the treatment of centrally located tumours.

15. VMAT
 The prostate, bladder, cervix and pituitary are critical sites
that can be treated by using VMAT techniques.
Rotation of gantry in VMAT technique

16. SBRT
 Stereotactic body radiation therapy (SBRT) refers to
delivery of highly conformal radiation dose to the target
volume by using multiple fractions.
 It involves the use of image guidance that indicates the exact
3D location of tumours, so that the radiation can be more
precisely delivered to cancer cells.
 This procedure uses many focused radiation beams to treat
tumours all over the body.

17. SBRT
 SBRT is typically used to treat small, early stage lung cancer
and the cancer of pancreas, liver, adrenal gland, spine etc.
 SBRT has shown dramatically better outcomes than
conventional radiation therapy as with the help of SBRT,
physicians are able to deliver a greater combined dose of
radiation over the course of far fewer treatments.

18. SRS
 Stereotactic radiosurgery (SRS) refers to the precise and
focused delivery of a high dose of radiation in a single
session which minimizes the damage of healthy tissue.
 It is not surgery in the traditional sense because there is no
incision. Instead, SRS uses 3D imaging to target high doses
of radiation to the affected area.
 This technique uses advanced imaging technologies
combined with sophisticated computer guidance to deliver a
high dose of photon radiation.

19. SRS
 SRS has become an increasingly common approach for
patients having 
 Deep brain tumours
 Pituitary tumours
 Cancer of eye
 Tumours in the lung
 Tumours in the liver
 Tumours in the spine
 Cancer of nasal cavity

20. SRS
 SRS can be delivered in 3 types 
i. Cyber knife
 Cyber knife radiosurgery is a precise, painless, non-
invasive radiation treatment where high radiation X–ray
beam is delivered from multiple points outside of the
patient body.
Patient is treating under
Cyber knife machine

21. SRS
ii. Gamma knife
 Gamma knife surgery is a computer guided treatment that
delivers highly focused radiation to tumours and lesions in
the brain.
An Elekta’s leksell
gamma knife machine

22. SRS
iii. X knife
 X knife is a non-invasive radiation treatment which is able to treat the
tumours anywhere in the body in 1–5 fractions.
 It is also known as LINAC based stereotactic radiosurgery as it uses 6
MV linear accelerator.
LINAC based radiosurgery
Or X knife