Radiotherapy uses radiation to treat cancer by damaging cancer cell DNA and destroying their ability to reproduce. There are two main types of radiotherapy - external beam radiotherapy which delivers radiation from outside the body using linear accelerators, and internal radiotherapy/brachytherapy which places radioactive sources inside the body. Radiotherapy aims to deliver an optimal dose to the tumor while minimizing damage to surrounding healthy tissues, and may have side effects like fatigue and skin reddening in treated areas.
5. RADIATION
THERAPY
RADIATION PHYSICS
Focused on the details of how, where, and how much energy can be
deposited in diseased tissue in the hopes of eradicating it, while
simultaneously minimizing the energy released in healthy tissue.
This process requires an understanding of the nature of the radiation
and the matter through which it passes and how that matter is
changed as a result of the energy deposition events.
RADIOBIOLOGY
the radiation response of cells at the molecular level
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Introduction
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* Use of ionizing radiation as part of cancer treatment to
control malignant cells
* Radiation therapy works by damaging the DNA within
cancer cells and destroying their ability to reproduce
* When the damaged cancer cells are destroyed by
radiation, the body naturally eliminates them.
* Normal cells can be affected by radiation, but they are
able to repair themselves
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1. Very advanced tumors
2. Probability of cure is very small or
negligible
3. Alleviate pain by reducing the size of a
tumor
4. E.g. bone metastasis
TO CURE CANCER
(Curative / adjuvant / therapeutic treatment) TO REDUCE SYMPTOMS
(Palliative)
1. Therapy has survival benefit, and it can be
curative
2. Destroy tumors that have not spread to other
body parts
3. Reduce the risk that cancer will return after
surgery or chemotherapy
4. Curative - curing a cancer, often with
combination with chemotherapy (e.g. Head
and Neck, cervical cancer)
5. Adjuvant - in addition to curative surgery to
reduce the risk of local recurrence (e.g. Breast
cancer)
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Radiation therapy is used two different ways:
(depend on tumor type, location, stage and general health of patient)
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Approximately 45 % are cured
22% – surgery
independently or in
combination
18% – radiation
therapy
independently or as a
leading method
5% – chemotherapy
independently or, more often, it is
combined with surgery and radiation
therapy
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Type of Radiation
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Directly
ionizing
radiation
Electron Proton Alpha
Indirectly
ionizing
radiation
X-ray Gamma ray Neutron
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Sources of radiation used in RT
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Linear accelerator
(Bremsstrahlung -
production)
High energy
x-rays
X – rays
(Low energy)
Conventional X-ray
tube &
Bremsstrahlung
production
Gamma rays
From Radioactive
Isotopes
(Radioactivity)
High energy
Electrons
Linear Accelerator
Thermionic emission
and acceleration.
all
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Types Of Radiation Therapy
External beam
radiotherapy
(EBRT/ XBRT) @
teletherapy
- outside the body
Brachytherapy
sealed radioactive sources
placed precisely in the
area under treatment
Nuclear
Medicine
infusion or oral ingestion
of unsealed radioactive
source
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16. EXTERNAL-BEAM
RADIATION THERAPY
3D CONFORMAL RADIATION THERAPY (3D-CRT)
Detailed 3-dimensional pictures of the cancer are created, typically
from CT. This allows the treatment team to aim the radiation therapy
more precisely.
INTENSITY MODULATED RADIATION THERAPY (IMRT)
the intensity of the radiation is varied within each field unlike 3D-
CRT. IMRT targets the tumor and avoids healthy tissue better than
conventional 3D-CRT.
PROTON BEAM THERAPY
The protons go to the targeted tumor and deposit the specific dose
of radiation therapy. Unlike with x-ray beams, there is very little
radiation dose beyond the tumor. This limits damage to nearby
healthy tissue.
IMAGE-GUIDED RADIATION THERAPY (IGRT)
This refers to the practice of using daily images of each treatment
field to confirm patient positioning and make sure the target is in the
field. This allows better targeting of the tumor and helps reduce
damage to healthy tissue.
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17. EXTERNAL-BEAM
RADIATION THERAPY
STEREOTACTIC RADIATION THERAPY (SRT)
This treatment delivers a large, precise radiation therapy dose to a
small tumor area. Head frames help limit movement.
INTENSITY MODULATED RADIATION THERAPY (IMRT)
Tomotherapy combines IMRT with the precision of CT scanning
technology where it is capable of capturing images in 3-D and
allows to verify patient’s setup position and to ensure high
precision of radiation doses delivered to the tumour.
Tomotherapy’s groundbreaking technology allows a single
radiation beam to be divided into thousands of tiny, narrow
beamlets that deliver radiation from all angles, in a pattern
planned by Clinical Oncologists and Medical Physicists,
coordinated by computers
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—SOMEONE FAMOUS
“This is a quote. Words full of wisdom
that someone important said and can
make the reader get inspired”
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—SOMEONE FAMOUS
“This is a quote. Words full of wisdom
that someone important said and can
make the reader get inspired”
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20. INTERNAL RADIATION
THERAPY PERMANENT IMPLANTS
These are tiny steel seeds that contain radioactive material. The
capsules are about the size of a grain of rice. They deliver most of the
radiation therapy around the implant area. But some radiation may
exit the patient’s body. This requires safety measures to protect
others from radiation exposure. Over time, the implants lose
radioactivity. And the inactive seeds remain in the body.
TEMPORARY INTERNAL RADIATION THERAPY
This is when radiation therapy is given in one of these ways:
Needles, catheters, applicators.The radiation stays in the body for
anywhere from a few minutes to a few days. Most people receive
radiation therapy for just a few minutes. Sometimes, people
receive internal radiation therapy for more time. If so, they stay in a
private room to limit other people's exposure to the radiation.
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Internal radiation therapy
is also called
brachytherapy. This type of
radiation therapy is when
radioactive material is
placed into the cancer or
surrounding tissue.
Implants may be
permanent or temporary
and may require a hospital
stay.
21. OTHER RADIATION
THERAPY
INTRAOPERATIVE RADIATION THERAPY (IORT)
Delivers radiation therapy to the tumor during surgery using either
external-beam or internal radiation therapy. IORT allows surgeons to
move away healthy tissue in advance.
SYSTEMIC RADIATION THERAPY
Patients swallow or receive an injection of radioactive material
that targets cancer cells. The radioactive material leaves the body
through saliva, sweat, and urine.
RADIOIMMUNOTHERAPY
This is a type of systemic therapy. It uses monoclonal antibodies,
which are proteins that are attracted to very specific markers on
the outside of cancer cells, to deliver radiation directly to the
tumors.
RADIOSENSITIZERS AND RADIOPROTECTORS
Radiosensitizers are substances that help radiation therapy better
destroy tumors. Radioprotectors are substances that protect healthy
tissues near the treatment area
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X –Rays
LINAC
X-rays
Single energy 4 or 6MV X-rays
Dual energy 6 and 15 or 18 MV
(low and high energy)
Electrons
4 MeV to 21 MeV - variable
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Risk
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Usually, temporary side
effects, such as fatigue
Radiotherapy can damage or
destroy normal cells as well as
destroying cancer cells and cause
treatment side effects
There may be a small risk of long
term, or late, permanent effects
from radiotherapy
Specific side effects within the area
being treated may include reddening
and itching of the skin
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