2. Cancer and Oncology
• Cancer is uncontrolled growth of cells. They grow
and form new cancerous cells.
• Not all tumors are cancer; tumors that aren’t cancer
are benign.
• Why uncontrolled growth?
• Treatment of cancer is opted on the basis of medical
reports and type of cancer.
3. Cancer and Oncology
• Types of treatment techniques-
1. External Beam Therapy
2. Brachytherapy
3. Chemotherapy
4. Causes and Types of cancer
• DNA damage may be caused by inherited
genetics, cigarette smoking or sun exposure, or
other environmental factors (Diet, Obesity,
Infections, Stress, and Lack of physical activity,
Environmental pollution, and Radiation). It is
difficult to know exactly
what caused any one person’s cancer.
5. Causes and Types of cancer
• Carcinoma
• Sarcoma
• Lymphoma and leukaemia
• Germ cell tumor and
• Blastoma
6. Treatment Techniques
SMS medical college provides cancer treatment by following
techniques
• Teletherapy
• Linear Accelerator
• Brachytherapy
7. Teletherapy
• Working-
• Main Components-
A. Radioactive source,
B. Source drawer,
C. Source head,
D. Collimator and gantry,
E. Base housing,
F. Patient support system and
G. Control console.
8. Radioactive Source
• Cobalt-60 is used as a gamma source in Bhabhatron.
Cobalt-60 emits high-energy gamma rays of 1.17
MeV and 1.33 MeV. Bhabhatron has the capacity to
load a 15 kilocurie source.
9. Source Drawer
• The source is assembled in a source drawer. The pneumatically driven
drawer moves the source between shielded (beam-off) position and
treatment (beam-on) position. The cylinder will withdraw the source
automatically to beam-off position, in case of any emergency. In
beam-off position, the shape, size and location of the radiation beam
can be visualized using a light beam.
10. Source Head
• Source head is a heavily shielded container. Depleted uranium
and lead are used as shielding materials in the source head.
Low source-to-skin distance of 80 cm is achieved, by compact
design of the source head and the collimator.
11. Collimator and gantry
• The collimator assembly controls the size, shape and orientation of the
radiation beam. It’s fully closable collimator. During any emergency,
the collimator closes fully, protecting the patient from over-exposure.
Two sets of trimmers are provided to reduce the penumbra of the beam.
• Gantry holds the source head and counter weight. It can rotate around
the patient on a horizontal axis by ±180°, allowing source positioning at
any point on a circle of 80 cm radius.
12. Base Housing and mainframe:
• The gantry is mounted on the mainframe. Entire unit is mounted on a steel base below
floor level. The base supports the mainframe.
Patient Support System:
• The patient positioning table or couch consists of a turntable mounted eccentrically with
the isocentre.
Control Console:
• Bhabhatron controller is fully computerized. Data of treatment session registered on
hard disk can be retrieved for control and analysis. Many safety interlocks are provided,
to prevent the patient from over-exposure to radiation.
13. Gap Correction
• There is a chance that some patient may miss their treatment
and report later, I this case we use gap correction. The gap
correction can be calculated by the formula-
𝐷𝑒𝑐𝑎𝑦 𝑓𝑎𝑐𝑡𝑜𝑟 = (
𝑡𝑟𝑒𝑎𝑡𝑒𝑑 𝑑𝑎𝑦𝑠
𝑇𝑟𝑒𝑎𝑡𝑒𝑑 𝑑𝑎𝑦𝑠+𝑟𝑒𝑠𝑡 𝑑𝑎𝑦𝑠
)^0.11
Here is data of some patient who missed their treatment for a few
days-
15. Linear Accelerator
Working-
Electrons are not accelerated by drift tube structure of
electrode, instead of that a waveguide is used for acceleration. A
traveling electromagnetic wave is made to propagate along the
axis of a metallic cylinder. This cylinder is known as waveguide.
Main Components-
Gantry;
a) Gantry stand or support;
b) Modulator cabinet;
c) Patient support assembly (i.e. treatment table) and
d) Control console.
17. Quality Control of Beam:
There are several systems built into the accelerator so that it will not deliver
a higher dose than the radiation oncologist has prescribed. Each morning
before any patients are treated, the radiation therapist performs checks on
the machine using a piece of equipment called a "tracker" to make sure that
the radiation intensity is uniform across the beam and that it is working
properly. In addition, the radiation physicist conducts more detailed weekly
and monthly checks of the linear accelerator
18. Quality Control of Beam:
Linac has two radiation detectors (ion chambers) to
calculate the dose given to patient. Dose is preset in the
system and as the desired dose is achieved beam is
closed
19. Effect of Radiation on Blood
When body is exposed to radiation it’s the blood that is always affected by the
radiation because every organ and tissue remains in life by blood supply and it’s
sensitivity to radiation also contributes to radiation effectiveness.
Irradiation of Blood outside the body is also practiced for research purpose as
well as in blood banks.
21. On an average five millions cells of Red Blood Cells per microliter are found in
human body (A 60 Kg person has 4.2 litres of blood in his body). WBC or White
Blood Cells count comes around 7000/µL and 64% of it is Granulocytes and 4% is
Lymphocytes.
RBC in Adults (males): 4.6 to 6.0 millions
(Females): 4.2 to 5.0 millions
Platelets that are responsible for preventing internal bleeding in human body
have their count from 150,000 to 450,000 per microliter of blood. Risk develops
when this count is decreased to 20,000. The blood was tested at CBC facility of
SMS Medical College Blood Bank.
Blood Components
22. Calculations and Results
• 𝑇𝑖𝑚𝑒 =
Required Dose
Calibrated Dose(per Second)∗Collimator Scattering 𝐹𝑎𝑐𝑡𝑜𝑟
S.No. Dose to be given (Gy) Time required (Minutes)
1. 2 1.52
2. 6 4.56
3. 10 15.2
4. 20 30.4
5. 50 76.01
26. Future Work
• 1. Blood irradiation can be done inside the body and
recovery of cells can be seen by taking samples time to time.
• 2. Effect on Head & Neck and Lung can also be checked after
irradiation for hypoxic condition.
• 3. Brain cancer patient can be a volunteer to see the effect
of radiation on brain as oxygen level is very low here.
• Blood Banks may use irradiation facility. (in some countries
this facility is available)
A cancer cell is a result of DNA damage, in case of normal cell, when DNA is damages the cell either repairs the damage or dies but in cancer cells this damage in DNA is carries to next generation cells instead of repairing or death.
In EBT normally gamma source or linac is used
In brachytherapy sealed radioactive source often contained in applicator tube is seeded in patient.
Chemotherapy is the treatment of cancer with one or more cytotoxic (Being toxic to cells) anti-neoplastic (Abnormal growth of cell preventing) drugs.
Carcinoma: Cancers derived from epithelial cells. Almost all cancers developing in the breast, lung, pancreas, and colon are carcinomas.
Sarcoma: Cancers arising from bone, cartilage, fat, nerve; each of which develop from cells originating inmesenchymal cells outside the bone marrow.
Lymphoma and leukaemia: These two classes of cancer derive from cells that make blood. Leukemia is the most common type of cancer in children.
Germ cell tumor: Cancers derived from pluripotent cells, most often presenting in the testicle or the ovary (seminoma and dysgerminoma, respectively).
Blastoma: Cancers arrive from immature "precursor" cells or embryonic tissue. Blastomas are more common in children than in older adults.
Bhabhatron is an isocentric, external-beam radiation therapy machine, using cobalt-60 isotope as radiation source. High-energy gamma rays emitted from the source are directed to the cancer site to destroy cancerous cells.
Linac can provide treatment by electron beam as well as by bremssatrahlung.
This type of treatment is given by placing sources directly into or near the volume to be treated. The dose is then delivered continuously, either over a short period of time (temporary implants) or over the lifetime of the source to a complete decay (permanent implants). Most common brachytherapy sources emit photons
Bhabhatron houses a Cobalt-60 source in a well-shielded containment. For treatment, the source is moved from shielded position to treatment position and the radiation beam is directed to the cancerous site, after controlling the beam to desired size, shape.
Cobalt-60 is used as a gamma source in Bhabhatron. Cobalt-60 emits high-energy gamma rays of 1.17 MeV and 1.33 MeV. Bhabhatron has the capacity to load a 15 kilocurie source.
The waveguide is a very long pipe, whose inside diameter is somewhat smaller than the free-space wavelength of the wave. If the waveguide were completely hollow the phase velocity of the wave inside would not equal the free space value. That’s why the tube contains equally spaced disks with holes in their centers to allow the passage of the beam. The disks load the waveguide so that the wave slowed down to desired velocity
There are two ion chambers because if one fails then other will inform the system that required dose has been given to patient and system commands automatically to stop the treatment.