Physics Principles in Medical Imaging

PHYSICS INVESTIGATORY PROJECT 2017
BIKRANT ROY 2017-18 Page 1
KENDRIYA VIDYALAYA BEG
YERWADA, PUNE - 411006
PHYSICS INVESTIGATORY
PROJECT
Physics Principle in Medicines
2017-2018 SUBMITTED BY:
BIKRANT ROY
CLASS XII A
ROLL NO. 4659889

CERTIFICATE
This is to certify that this “Physics Investigatory Project” on the
topic “Physics Principle in Medical System” has been successfully
completed by Bikrant ROY of class XII – A under the guidance of
Mr. Rajesh Kumar in particular fulfilment of the curriculum of
Central Board of Secondary Education {CBSE} leading to the
award of annual examination of the year 2017-18.
TEACHER IN- CHARGE EXTERNAL EXAMINER
PRINCIPAL

ACKNOWLEDGEMENTS
I have taken efforts in this project. However, it would not have been possible
without the kind support and help of many individuals.
I would like to thank my principal, Mr. RK Lale, and school for providing me
with facilities required to do my project.
I would also thank our Physics lab assistant, Mr. Ingale Sir, for helping me with
the techniques, procedures, how to do that particular thing, etc. and let me do my
project successfully.
I am highly indebted to my Physics teacher, Mr. Rajesh Kumar, for his
invaluable guidance which has sustained my efforts in all the stages of this
project work.
I would also like to thank my parents for their continuous support and
encouragement.
My thanks and appreciations also go to my fellow classmates in developing the
project and to the people who have willingly helped me out with their abilities.

INDEX
Serial
No.
CONTENTS
1. CERTIFICATE
2. ACKNOWLEDGEMENT
3. X-RAYS
4. MRI
5. CT SCAN
6. SOME OTHER RELATED AREAS

X-RAY
What are X-Rays?
➢ X-Rays are a form of electromagnetic radiation.
➢ One of the most common and beneficial uses of X-rays is for medical imaging. X-rays
are also used in treating cancer and exploring the cosmos.
Types of X-Rays
X-rays are roughly classified into two types:
I. Hard X-rays
II. Soft X-rays
Soft X-Rays
Soft X-rays fall in the range of the EM spectrum between (UV) light and gamma-rays. Soft
X-rays have comparatively high frequencies — about 3 × 1016
cycles per second, or hertz, to
about 1018
Hz — and relatively short wavelengths — about 10 nm, or 4 × 10-7
inches, to
about 100 pm, or 4 × 10-8
inches.
Hard X-Rays
Hard X-rays have frequencies of about 1018
Hz to higher than 1020
Hz and wavelengths of
about 100 pm (4 × 10-9
inches) to about 1 pm (4 × 10-11
inches). Hard X-rays occupy the
same region of the EM spectrum as gamma-rays1
.
1
The only difference between them is their source: X-rays are produced by accelerating electrons, while
gamma-rays are produced by atomic nuclei.

Production of X-rays
Block diagram of X-ray machine

OPERATION/WORKING OF X-RAY MACHINE
High voltage source and high voltage transformer
High voltage source is responsible for providing high voltage to the H.V transformer for a
decided time. The H.V transformer produces 20 kV to 200 kV at the O/P. These voltages are
used to determine the contrast of the image. High voltages have higher contrast.
High voltage rectifier
This rectifier rectifies the high voltage produced by the H.V.T and supplies them to the anode
of the X-ray tube.
Thermal overload detector
The heat of the X-ray tube anodes are rotated by an induction motor, in order to limit beam
power at any spot and help to cool the anode.
Pulse duration timer
The duration of the time must be very small so that
1. the patient doesn’t receive the excessive dose,
2. the film doesn’t become over exposed, and
3. The X-ray tube doesn’t overheat.
The pulse duration timer determines this pulse duration.

Aluminium filter
The X-ray beam used in the medical field contains a broad band of frequencies. The
unwanted frequencies in the X-ray based create side effects e.g. extra dose for patient causing
tumour also reduce the contrast in the image. These are called soft X-rays. To eliminate these
effects Aluminium filter is used.
Collimator
Another mean to reduce the dose of patient is to confine the X-ray beam only on the region of
interest on the body of the patient. An external collimator placed between patient and filter
does this.
Diaphragm
X-rays inside the patient create X-ray scattering, which tends to burn the image to absorb the
scattered X-rays and eliminate the burning of an image a lead grid is used which is called
diaphragm.
Film and Lead shield
The X-rays passed from the desired region of the patient body are made to strike on the film
where they produce an image of the body soft and hard parts. A lead shield is used to collect
the X-ray after striking on the film.
The H.V source produces high voltage supply, which are rectified by rectifier and applied to
anode of the X-ray tube. Filament supply is also provided. As a result, X-rays tube producing
an X-ray beam which is passed through the body and produces image of body and the film,
which is examined in the laboratory.

APPLICATION OF THE X-RAY
Detection of
1. Any fracture in the bones.
2. Infection of lungs, kidneys and other injuries.
3. Presence of tumour.
4. X-rays are used for the treatment of tumour.
Uses of the X-rays in the Industries
X-rays are used
1. For industrial radiography2
and fluoroscopy3
.
2. For measuring the thickness of the material.
3. For inspection of metals.
4. For inspection of fruits before packaging.
2
It uses X-rays for inspection of industrial parts, particularly welds.
3
It is an imaging technique used to obtain real-time moving images of the internal structures of a patient
through the use of a fluoroscope.

MAGNETIC RESONANCE IMAGING (MRI)
What is MRI?
Magnetic Resonance Imaging (MRI) is a medical imaging technique used in radiology to
investigate the anatomy and physiology of the body and the physics of the technique involves
the interaction of the matter with electromagnetic field.
Types of MRI Scanners
1. High-Field MRI Scanners
2. Low-Field MRI Scanners
3. Traditional closed MRI Scanner
4. Open MRI Scanner
5. Standing or Sitting MRI Scanner

A MRI Scanner
Block Diagram of a MRI Scanner

WORKING OF MRI MACHINE
MRIs employ powerful magnets which produce a strong magnetic field that forces protons in
the body to align with that field. When a radiofrequency current is then pulsed through the
patient, the protons are stimulated, and spin out of equilibrium, straining against the pull of
the magnetic field. When the radiofrequency field is turned off, the MRI sensors are able to
detect the energy released as the protons realign with the magnetic field. The time it takes for
the protons to realign with the magnetic field, as well as the amount of energy released
changes depending on the environment and the chemical nature of the molecules. Physicians
are able to tell the difference between various types of tissues based on these magnetic
properties.
To obtain an MRI image, a patient is placed inside a large magnet and must remain very still
during the imaging process in order not to blur the image. Contrast agents (often containing
the element Gadolinium) may be given to a patient intravenously before or during the MRI to
increase the speed at which protons realign with the magnetic field. The faster the protons
realign, the brighter the image.

Uses of MRI in Medicine
MR imaging of the body is performed to evaluate:
• Organs of the chest and abdomen—including the heart, liver, biliary4
tract, kidneys,
spleen, bowel, pancreas, and adrenal5
glands.
• Pelvic organs including the bladder and the reproductive organs such as the uterus and
ovaries in females and the prostate gland in males.
• Blood vessels (including MR Angiography).
• Lymph nodes.
Physicians use an MR examination to help diagnose or monitor treatment for conditions such
as:
• Tumours of the chest, abdomen or pelvis.
• Diseases of the liver, such as cirrhosis, and abnormalities of the bile ducts and
pancreas.
• Inflammatory bowel disease such as Crohn’s disease6
and ulcerative colitis.
• Heart problems, such as congenital heart disease.
• Malformations of the blood vessels and inflammation of the vessels (vasculitis).
• A foetus in the womb of a pregnant woman.
4
The liver, gall bladder and bile ducts constitute the biliary tract.
5
Endocrine gland, found over the kidneys.
6
A chronic inflammatory bowel disease that affect the lining of the digestive tract.

Advantages of MRI
1. Excellent soft tissue contrast resolution.
2. Ability to obtain direct transverse, sagittal, coronal and oblique images.
3. Doesn’t use ionising radiation.
4. Doesn’t produce bone/air artefacts.
Disadvantages of MRI
1. Longer imaging time.
2. Complexity of the equipment and scan acquisition.
3. High cost.
4. Inability to demonstrate calcification or cortical bone details.

CT SCAN
A computerized tomography (CT) or computerized axial tomography (CAT) scan
combines data from several X-rays to produce a detailed image of structures inside the body.
CT scans produce 2-dimensional images of a "slice" or section of the body, but the data can
also be used to construct 3-dimensional images. A CT scan can be compared to looking at
one slice of bread within a whole loaf.
CT scans are used in hospitals worldwide.
When is a CT scan used?
It is useful for obtaining images of:
• Soft tissues
• The pelvis
• Blood vessels
• Lungs
• Brain
• Abdomen
• Bones
CT is often the preferred way of diagnosing many cancers, such as liver, lung, and pancreatic
cancers.

The image allows a doctor to confirm the presence and location of a tumor, its size, and how
much it has affected nearby tissue.
A CT scan can reveal tumours, abnormal tissue, and problems with arteries.
A scan of the head can provide important information about the brain, for instance, if there is
any bleeding, swelling of the arteries, or a tumour.
A CT scan can reveal a tumour in the abdomen, and any swelling or inflammation in nearby
internal organs. It can show any lacerations of the spleen, kidneys, or liver.
As a CT scan detects abnormal tissue, it is useful for planning areas for radiotherapy and
biopsies, and it can provide valuable data on blood flow and other vascular conditions.
It can help a doctor assess bone diseases, bone density, and the state of the patient's spine. It
can also provide vital data about injuries to a patient's hands, feet, and other skeletal
structures. Even small bones are clearly visible from their surrounding tissue.

CT scanner block diagram

CT scanner
Advantages of CT
1. Highly Detailed
2. Painless
3. Precise
Disadvantages of CT
1. Radiation
2. Allergic reaction7
3. Misinterpretation8
7
People who undergoes a CT scan often receive a dose of what’s known as “contrast material” which contains
iodine, which leads to allergic reaction
8
CT Scan being so detailed alert the doctor of some minor abnormalities in the body that don’t cause any
problem but doctors can indulge leading to unnecessary complexities.

SOME OTHER RELATED AREAS
Another physics-related advancement in medicine is the field of Nuclear Medicine, which
uses gamma-emitting radiotracers for single-photon emission tomography, or SPECT
scans.
SPECT scans use a gamma camera to record images at a series of angles around the patient,
then reconstruct them to produce 3D cross-sectioned images of organs and how they’re
functioning in the body -- like showing how blood flows to your heart or which areas of your
brain are more or less active.
SPECT imaging uses radioactive isotopes that have longer half-lives than the ones used for
PET scans, and are both more common and less expensive.
SPECT scans are particularly adept at helping detect brain disorders like dementia9
, clogged
blood vessels, seizures10
, epilepsy11
, and head injuries. They are also helpful in detecting
heart problems such as clogged arteries and reduced pumping efficiency, as well as bone
disorders like hidden fractures or tumours.
9
A group of thinking and social symptoms that interferes with the daily functioning of our lives.
10
A disorder in which nerve cell activity in the brain is disturbed, causing seizures.
11
Also called seizure disorder.

Bibliography
❖ www.google.co.in
❖ https://en.wikipedia.org
❖ Reference articles from various blogs.

Physics Principles in Medical Imaging

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