VCE Physics

Unit 1

Topic 3

Medical Physics

Unit Outline

• This unit covers the following topics• describe applications of radioisotopes to medical diagnosis and treatment;

• explain the use and operation of optical fibres in endoscopes and in other applications for diagnosis and treatment;

• describe and evaluate the use of lasers as intense energy sources for medical treatments;

• describe and compare processes of, and images produced by, medical imaging using two or more of ultrasound, X-rays, CT, MRI and PET;

• identify and apply safe and responsible practices when working with radioactive material and completing investigations.

Chapter 1

Nuclear Medicine:

Radioisotopes

1.0 Nuclear Medicine – A Little History

Medical uses of radioactive elements had its beginnings in the work of the Curies, Pierre (1859 – 1906)

Together they discovered two highly radioactive elements Polonium (400 times more radioactive than Uranium) and Radium (900 times more radioactive).

The first recorded medical use of a radioactive substance occurred in France in 1901 when radium was used as a cancer treatment.The first recorded radium use in Australia was by a Melbourne dermatologist in 1903.

The first diagnostic use of a radioisotope was in 1924 when a decay product of Radium was injected into the bloodstream and its movement through the body was recorded with a geiger counter.

and his wife Marie (1867 – 1934).

1.1 RadioisotopesRadioisotopes (sometimes called radionuclides) are unstable atoms which, in searching for stability, emit either energy (in the form of gamma rays), or matter (in the form of neutrons, alpha or beta particles).

Radioisotopes are used in many areas:In Agriculture - to investigate plant growth and fertiliser take up.In Industry - to check important welds in pipes etc, and to measure metal thickness.In Archaeology - to carbon date ancient objects.In Sewage Disposal - to trace water flows.In Medicine – to detect and treat disease.

Radioisotopes can be naturally occurring, eg Carbon-14 (14C) or man made, eg Cobalt-60 (60Co).Man made radionuclides are manufactured in either a Cyclotron (a particle accelerator) or in a nuclear reactor which, in Australia’s case, is located at Lucas Heights, just south of Sydney.

1.2 Medical Radioisotopes When used in Medicine, radioisotopes

fall into one of two groups:1. Diagnostic Radionuclides2. Therapeutic Radionuclides

Treatment of thyroid cancers2.6 MinutesIodine – 131 (131I)

Treatment of Tumors27.7 YearsStrontium - 90 (90Sr)

Treatment of Cancer5.3 YearsCobalt - 60 (60Co)

Diagnosis of various diseases

6 HoursTechnetium - 99m (99mTc)

Diagnosis of Blood Disease46.3 DaysIron – 59 (59Fe)

Study of general biological processes

15 HoursSodium – 24 (24Na)

UsesHalf LifeRadioisotope

A representative list of medical radioisotopes is shown in the table

1.3 Diagnostic RadioisotopesTo be useful as a diagnostic tool,

a radioisotope must meet certain criteria. It must: (a) have a short half life,

ideally about the same as the time required to perform the diagnosis.

(b) not emit alpha or beta radiation, because they would be trapped inside the patient and could not be detected externally.

(c) emit gamma radiation which is energetic enough to allow its exact source to be identified.

(d) be energetic enough to provide useful clinical information but not so energetic as to be dangerous to the patient.

From a field of more than 2300 radioisotopes, only a handful come close to satisfying the criteria for use as diagnostic tools.Of these, the reactor produced Technetium – 99m, is by far the best, being used in more that 80% of all nuclear diagnostic tests performed.Note: the m in the symbol 99mTc means this is the “metastable” form of Tc, which radiates gamma rays and low energy electrons.

1.4 Technetium 99m

These are: a. It has a half-life of six hours which is long enough to

examine metabolic processes yet short enough to minimise the radiation dose to the patient.

b. Technetium-99m decays by an "isomeric" process which emits gamma rays and low energy electrons. Since there is no high energy beta emission the radiation dose to the patient is low.

c. The low energy gamma rays it emits easily escape the human body and are accurately detected by a gamma camera. Once again the radiation dose to the patient is minimised.

d. The chemistry of technetium is so versatile it can form tracers by being incorporated into a range of biologically-active substances to ensure that it concentrates in the tissue or organ of interest.

The radioisotope most widely used in medicine is technetium-99m.It is an isotope of the reactor-produced element technetium and it has almost ideal characteristics for a nuclear medicine scan.

1.5 Technetium Delivery

The generator consists of a lead pot enclosing a glass tube containing the radioisotope, is supplied to hospitals from the nuclear reactor where the isotopes are made.

It contains molybdenum-99, with a half-life of 66 hours, which progressively decays to technetium-99m.

Technetium generators are popularly known as “technetium cows” because they can be “milked” of technetium as needed.

The Tc-99m is washed out of the lead pot by saline solution when it is required.

The generator is exhausted after approximately two weeks and returned for recharging.

1.6 The Gamma Camera

The gamma ray photons are detected by a gamma camera which can view organs from many different angles.

The camera builds up an image from the points from which radiation is emitted.

This image is enhanced by a computer and viewed by a physician on a monitor for indications of abnormal conditions.

Gamma Camera

Once produced, 99mTc is linked to chemical compounds which permit specific physiological processes to be scrutinised.

It can be given by injection, inhalation or orally.

1.7 Diagnosis

Organ malfunction can be indicated if the isotope is either partially taken up in the organ (cold spot), or taken up in excess (hot spot).A series of images are taken over a period of time that show unusual patterns or rates of isotope movement could indicate malfunction in the organ.

Positioning of the radiation source within the body is the fundamental difference between nuclear medicine imaging and other imaging techniques such as x-rays. Gamma imaging provides a view of the position and concentration of the radioisotope within the body.

A distinct advantage of nuclear imaging over x-ray techniques is that both bone and soft tissue can be imaged very successfully. This has led to its common use in developed countries where the probability of anyone having such a test is about one in two and rising.

1.8 Therapeutic Radioisotopes

External irradiation can be carried out using a gamma beam from a radioactive cobalt-60 source, though in developed countries the much more versatile linear accelerators are now being utilised as a high-energy x-ray source (gamma and x-rays are much the same).

They are produced in wire form and are introduced through a catheter to the target area. After administering the correct dose, the implant wire is removed to shielded storage. This procedure gives less overall radiation to the body, is more localised to the target tumour and is cost effective.

Internal radiotherapy is by administering or planting a small radiation source, usually a gamma or beta emitter, in the target area. Iodine-131 is commonly used to treat thyroid cancer, probably the most successful kind of cancer treatment. Iridium-192 implants are used especially in the head and breast.

Rapidly dividing cells are particularly sensitive to damage by radiation. For this reason, some cancerous growths can be controlled or eliminated by irradiating the area containing the growth.

1.9 A Cure for Anything !At present, approximately 35 radioisotopes are commonly used in the detection and treatment of illness or disease. Those used for treatment include:

Radioisotope Use

Dysprosium-165: Treatment, arthritisIodine-125: Treatment, cancer of prostate, brainIodine-131: Treatment, cancer of thryoidPhosphorus-32: Treatment, excess red blood cellsRhenium-188: Treatment, coronary artery diseaseSamarium-153: Treatment, breast, prostate cancersBoron – 10: Treatment, brain tumours

Cobalt – 60: External cancer radiation

Chapter 2

Optical Instruments: Endoscopes

2.0 Endoscopes

In rigid endoscopes the image is conveyed by a relay of lenses. The classical rigid endoscopes have a number of periscopic and field lenses in order to convey the image from distal end to the eyepiece. Generally, a flexible endoscope is referred to as a fibrescope. In flexible endoscopes, a bundle of precisely aligned flexible optical fibres is used.

The name endoscope is derived from two Greek words: endom (within) and skopein (view). The endoscope is an optical instrument used for viewing internal organs through natural openings (ear, throat, rectum, etc.) or through a small incision in the skin.

Various rigid & flexible endoscopes

There are 2 basic types of endoscopes: Rigid and Flexible

2.1 Endoscopes – Some History

In 1930, German medical student, Heinrich Lamm was the first person to assemble a bundle of optical fibres to carry an image. Lamm's goal was to look inside inaccessible parts of the body. During his experiments, he reported transmitting the image of a light bulb. However the image was of poor quality.

The first endoscope made of optical fibres (fibrescope) was used for viewing the stomach and esophagus at the University of Michigan School of Medicine in 1957. Since then, there has been rapid progress in endoscope development.

The concept of endoscopy originated in the early 19th century. Philip Bonzini, an Italian doctor, is credited with the first use of a rigid endoscope in humans in the early 1800’s

2.2 Principles of Optical FibresTotal internal reflection (TIR) is the most important phenomenon for the guiding of light in optical fibres. With TIR light can be completely reflected at the optical fibre surface without any reflective coating. TIR can only occur for light travelling from a more dense to a less dense medium.

Optical Fibre

Cladding

Cladding

n1

n2

n2

θ1 θ1

Some Reflected Light

Lost Light

θ1< θC

All Light Reflected

θ2 θ2

θ2> θC

θC

Critical Angle

n1 > n2

Thus, in the diagram, the refractive index of the actual optical fibre n1 is greater than that of the cladding n2 .

For light with with θ < θC , much of the light is refracted out of the optical fibre

For TIR to occur the angle of incidence (θ) must be greater than the critical angle (θC)

For light with θ = θC , all light is refracted so it just grazes the surface of the fibre For light with θ > θC , light is totally internally reflected and will continue to do so whenever it strikes the fibre’s surface.

2.3 Optical Fibre ConstructionFibre Type Cross Section Refractive Index Profile

Step Index

r

RI

rn1n2

n1

n2

Graded Index

rn2 n1

r

RIn1

n2

Usually optical fibres are flexible, thin, cylindrical and made of transparent materials such as glass and plastic. The most abundant and widespread material used to make optical fibre is glass and most often this is an oxide glass based on silica (SiO2) with some additives. The required properties for an optical fibre are:optical quality, mechanical strength, and flexibility. For these reasons, plastic optical fibres have been made with polymethylmeth-acrylate (PMMA). They have a “tighter turning circle” than glass fibres. In general, optical fibres have a cylindrical core and are surrounded by a cladding. If both Refractive Indexes, (n1) and (n2) are uniform across their cross sections, the fibre is called a STEP INDEX FIBRE (SI) .If (n1) varies with the core radius (i.e., (n1) gradually decreases from the centre of the core to n2 at the outer radius), it is a GRADED INDEX FIBRE (GRIN).

2.4 Step vs Graded FibresCladding

Step Index Fibre

Core

Fibre Accptance

Cone

In SI fibre, the light rays zigzag between the core/cladding on each side of the fibre axis.

Fibre Accptance

Cone

Graded Index Fibre

CoreIn GRIN fibre, the gradient in the refractive index gradually bends the rays back toward the axis.

The Fibre Acceptance Cone represents the range of angles for which the incidence angles are greater than the critical angle

2.5 Fibre BundlesIt is impossible for a single fibre to transmit an image. An individual fibre can transmit only a spot of a certain color and intensity. To transmit an image, a large number of single fibres must be aligned and fused together. This means assembly of optical fibres in which the fibres are ordered in exactly the same way at both ends of the bundle to create an image. This type of fibre bundle is called a Coherent Bundle

(a) is a low power endoscope

(b) is a high power endoscopeObject seen by

endoscopeImage projected to

eyepiece

Object seen by endoscope

Image projected to eyepiece

Incoherent Bundles are groups of fibres which are not ordered at both ends. They are used as light pipes to bring light from an external source down the endoscope to illuminate the area under view.

2.6 Endoscope Construction Fibre Optic Endoscopes

have a number of basic components:

1. A Coherent Bundle for bringing the image to the eyepiece (or video monitor).

2. An Incoherent Bundle for taking an external light source down the endoscope to illuminate the viewing area.

3. Optional tubes or channels for the passage of air, water, as well as remote control implements such as biopsy forceps or cytology brushes.

A piece of dried pork crackling stuck

in oesophagus

A Ball Bearing lodged in the oesophagus

A coin in the stomach

Endoscopic “Pictures”

Stomach Ulcer

2.7 Endoscope Man

ARTHROSCOPE

An incredible number of endoscopes have been developed for both diagnosis and treatment.Some of the more common are shown on “Endoscope Man”

Famous in “Aussie Rules” for investigating knee injuries

Most commonly used endoscope in general

surgery.

Ultra thin endoscope for investigating blood vessels

Typical Rigid Endoscope

Chapter 3

Lasers &

Laser Treatments

3.0 Laser Basics"Laser" is an acronym for Light Amplification by Stimulated Emission of Radiation.

Typically, very intense flashes of light from a flash tube (or from an electrical discharge pump) enter the lasing medium and create a large collection of excited-state atoms (atoms with higher- energy electrons).

Although there are many types of lasers, all have certain common features. In explaining laser operation, the common ruby laser will be used as an example.

Ruby Atoms

Flash Tube

Mirror

Partially silvered mirror

In a laser, the lasing medium (the ruby crystal) is so called “pumped” to get the electrons of the ruby atoms into an excited state.

These excited electrons then release their excess energy as photons of red light.

Ruby Atoms

Ruby Crystal

These red photons rush back and forth finally exiting the tube as a coherent beam

3.1 Laser Types

Ruby Laser

Letters etched on a human hair using an Eximer Laser

Since their development in 1960, lasers used in medicine and surgery have evolved, and while medical lasers have never become the "magic ray" that some had hoped, they have become powerful and indispensable tools in clinical practice.There are many medical laser systems available today, but they all use the principal of selective photothermolysis which means getting the right amount of the right wavelength of laser energy to the right tissue to damage or destroy only that tissue, and nothing else.

Note: YAG = Yttrium-Aluminium- Garnett KTP = potassium-titanyl-phosphate

Some of the many medical and surgical lasers in use.

3.1 Laser Types & Treatments

Laser eye correction193Eximer

Retinal and ear surgery, removal of birthmarks488 to 514Argon

Cutting tissue, red/yellow tattoo ink removal532KTP

Treatment of port wine birthmarks and spider veins577 to 585Pulsed Dye

Treatment and removal of moles, freckles, birthmarks694Ruby

Blue/black ink tattoo removal; hair removal755Alexandrite

Hair removal; dental surgery800 to 900Diode

Blue/black ink tattoo removal; hair removal1064Nd: YAG

Shaving bones (eg, arthroscopes), kidney stone remov 2070Ho: YAG

“Shaving” of skin to remove wrinkles2940Er: YAG

Surgery (used as a “scalpel”) 10,600CO22

UseWavelength (nm)

Laser

Tattoo removal using Nd:YAG laser

Chapter 4

Ultrasound

4.0 Ultrasound Basics Definition of UltrasoundSound consists of travelling pressure waves Speed of sound waves in human tissue: ~ 1500 ms-1. Frequency range: between 2 MHz and 10 MHz Ultrasound is produced using piezo-electric transducers, crystals which change shape under the action of an electric field. Quartz is the most commonly known piezo-electric material.

Better performing piezo – electric materials (such as BARIUM TITANATE or LEAD ZIRCONATE) is formed into disks.

Variable frequencyA.C Voltage:

V = VoCos 2π ft

The disk is placed between 2 electrodes and applying a voltage

causes the crystal to vibrate.

The crystal will vibrate at the same frequency as the supply voltage, producing sound waves

with frequencies between 2 and 10 MHz

The crystal’s vibrations set up Ultrasonic sound waves in the medium around the crystal

4.1 Echo LocationUltrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes. The technique is similar to the echolocation used by bats, whales and dolphins, as well as SONAR used by submarines.

The ultrasound signals generated as previously described leave the handpiece and are reflected back from various tissues and bones.

These reflected waves strike the handpiece causing the piezo electric crystal to contract and expand.This change in shape causes a voltage to be generated which is then processed into a “picture”.

4.2 Ultrasonic SpeedsWhen ultrasonic waves are applied to various body tissues they travel at varying speeds from a low of 1450 ms-1 through fat to a high of 4080 ms-1 through skull bone.

Ultrasound image of yolk sac and fetus at 6 week gestation.

4.3 Sound Intensity ProfileField Zones

Near Field - the region of a sound beam in which the beam diameter decreases as the distance from the transducer increases. This zone is called the Fresnel (Fra-nel, the s is silent) zone.

Focal Zone - the region where the beam diameter is most concentrated giving the greatest degree of focus.

Far Field - the region where the beam diameter increases as the distance from the transducer increases. This zone is called the Fraunhoffer zone

Beam Properties:

Longitudinal Waves - the wave in which the particle motion is parallel to the direction of the wave travel. A series of longitudinal waves make up the ultrasound beam.

The best ultrasound images are produced with the transducer operating in the Focal Zone.

4.4 An Ultrasound ExaminationIn ultrasound examination, the following events happen:

1. High-frequency sound pulses are transmitted into your body using a probe.

2. The waves travel into your body and hit a boundary between tissues (e.g. between fluid and soft tissue, soft tissue and bone).

3. Some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and get reflected.

4. The reflected waves are picked up by the probe and relayed to the machine.

5. The machine calculates the distance from the probe to the tissue or organ (boundaries) using the speed of sound in tissue and the time of the each echo's return (usually on the order of millionths of a second).

6. The machine displays the distances and intensities of the echoes on the screen, forming a two dimensional image.

Below is an Ultrasound image of a growing fetus (approximately 12 weeks old) inside a mother's uterus. This is a side view of the baby, showing:

HeadNeck

Torso

Legs

4.5 Ultrasound in 3D

In the past few years, ultrasound machines capable of three-dimensional imaging have been developed. In these machines, several two-dimensional images are acquired by moving the probes across the body surface or rotating inserted probes. The two-dimensional scans are then combined by specialized computer software to form 3-D images.

3-D ultrasound images Photo courtesy Philips Research

The same computer technology is used to produce the famous “dancing babies”

images

4.6 Doppler Ultrasound

How much the frequency is changed depends upon how fast the object is moving. Doppler ultrasound measures the change in frequency of the echoes to calculate how fast an object is moving. Doppler ultrasound has been used mostly to measure the rate of blood flow through the heart and major arteries.

Doppler ultrasound is based upon the Doppler Effect. When the object reflecting the ultrasound waves is moving, it changes the frequency of the echoes, creating a higher frequency if it is moving toward the probe and a lower frequency if it is moving away from the probe.

Chapter 5

X Rays

5.0 X raysWilhelm Conrad Roentgen (1845-1923)

The “first X ray”

In 1895 Röntgen was studying what happened when an electric current was passed through a gas of extremely low pressure in apparatus called Crooke’s Tubes.

Roentgen found that, if the discharge tube is enclosed in a sealed, thick black carton to exclude all light, and if he worked in a dark room, a paper plate covered on one side with the compound barium platinocyanide placed in the path of the rays became fluorescent (gave out a greenish light) even when it was as far as two metres from the discharge tube

Following this discovery, he asked his wife to hold her hand in the path of rays between the tube and a photographic plate. He observed, after developing the plate, an image of his wife's hand which showed the shadows thrown by the bones of her hand and that of a ring she was wearing.

Because the nature of the new rays was then unknown, he gave them the name X-rays. Later it was shown that they are of the same electromagnetic nature as light, but differ from it only in the higher frequency of their vibration.

5.1 X Ray Production

Inside the machine is an x-ray tube.An electron gun inside the tube shoots high energy electrons at a target made of heavy atoms, such as tungsten. X-rays come out because of atomic processes induced by the energetic electrons shot at the target.

There are two different atomic processes that can produce x-ray photons. 1. The first is called Bremsstrahlung, which is a fancy German name meaning "braking radiation."

2. The other is called K-shell emission. They can both occur in heavy atoms like tungsten.

An x-ray machine, like that used in a doctor's or a dentist's office, is really very simple.

Individual Photon

X-rays are just like any other kind of electromagnetic radiation. They are produced in parcels of energy called photons, just like light.

5.2 Types of X Rays

This electron slows down after swinging around the nucleus of a tungsten atom and loses energy by radiating x-rays.In this process, a lot of photons of different wavelengths are produced, but none of the photons has more energy than the electron had to begin with. After emitting the spectrum of x-ray radiation the original electron is slowed down or stopped.

2. K Shell. The K-shell is the lowest energy state of an atom.

1. Bremsstrahlung. This form of X radiation occurs when the velocity of electrons fired towards the tungsten nucleus changes.

K-shell emission produces higher-intensity x-rays than Bremsstrahlung, and the x-ray photon comes out at a single wavelength.

The incoming electron can give the K shell electron enough energy to knock it out of its energy state. Then, a tungsten electron of higher energy (from an outer shell) can fall into the K-shell. The energy lost by the falling electron shows up in an emitted x-ray photon. Meanwhile, higher energy electrons fall into the vacated energy state in the outer shell, and so on.

5.3 X Ray Diagnostics

X rays are most commonly used for investigation of the skeleton, the diagnosis of broken bones and the display of the effects of trauma on the body.

Broken Femur

Steel spikes in wrist

Shotgun Pellets

Shattered Femur

Chapter 6

CT Scans

6.0 CT ScansCT or Computerised Tomography, also know as CAT or Computerised Axial Tomography Scans use an X-ray source coupled with an X-ray detector on the opposite side of the body, which are rotated together to give a cross-sectional picture of the body at one level or cut.

COMPUTED AXIAL TOMOGRAPHY

CAT Scan of thePelvic Region• Images the body using X-rays.• Initial research: 1960s• Applied research: 1970s-80s• X-rays are sent through the body at various angles, resulting in cross-sectional images.

One of the first dedicated head CT scanners, in 1974

CT scans are of greatest value for showing physical changes in tissue, although small tumours may be missed if absorption properties are like those of normal tissue.

6.1 CT - HistoryTomography is from the Greek word "tomos" meaning "slice" or "section" and graphia meaning "describing". CT was invented in 1972 by British engineer Godfrey Hounsfield of EMI Laboratories, England, and independently by South African born physicist Allan Cormack of Tufts University, Massachusetts.

The first clinical CT scanners were installed between 1974 and 1976. The original systems were dedicated to head imaging only, but "whole body" systems with larger patient openings became available in 1976. CT became widely available by about 1980. There are now 30,000 installed worldwide. The first CT scanner took several hours to acquire the raw data for a single scan or "slice" and took days to reconstruct a single image from this raw data. The latest multi-slice CT systems can collect up to 4 slices of data in about 350 ms and reconstruct a 512 x 512-matrix image from millions of data points in less than a second. An entire chest (forty 8 mm slices) can be scanned in five to ten seconds using the most advanced multi-slice CT system.

Original CT image from scanner circa 1975. This image is a coarse 128 x 128 matrix, showing a slice of the brain

CT image of a normal brain using a state-of-the-art CT system and a 512 x 512 matrix image.

Chapter 7

PET Scans

7.1 PET ScansA PET scan provides a color-coded image of a body organ in function rather than its structure.

Positron Emission Tomography, or PET, scanning is an imaging technique that uses radioactive positrons (positively charged particles) to detect subtle changes in the body's metabolism and chemical activities.

There the tracer emits positrons, which collide with electrons (negatively charged particles), producing gamma rays (similar to X-rays). These gamma rays are detected by a ringed-shaped PET scanner and analyzed by a computer to form an image of the target organ's metabolism or other functions.

This tracer is typically a chemical that is normally found in the body (carbon, nitrogen, oxygen) that has been altered to allow it to emit positrons. Once the tracer enters the body, it travels through the bloodstream to a specific target organ, such as the brain or heart.

Human Brain Performing

PET Scanner

During a PET scan, a positron-producing radioisotope called a tracer is either injected into a vein or inhaled as a gas.

Chapter 8

MRI Scans

8.0 MRI - Basic Operation

MRI takes advantage of the fact that the nuclei of certain atoms, hydrogen and phosphorous, in particular, behave like a magnet.

MRI (Magnetic Resonance Imaging) started out as a tomographic imaging (CT) technique, that is, it produced an image of a thin slice through the human body.MRI has advanced beyond a tomographic imaging technique to a volume imaging technique.

When the field is turned-off, the nuclei against the field spin and release a characteristic radio- frequency photon emission.

The human body is primarily fat and water. Both fat and water have many hydrogen atoms which make the human body roughly 63% hydrogen atoms.

Typical MRI Scanner

When those atoms are placed in a strong magnetic field, their nuclei align the axis of spin either with or against the direction of the field.

In the absence of an external magnetic field, these hydrogen atoms are not lined up in any particular direction.

These emissions are collected and fed into a computer which produces the MRI image.

8.1 MRI Scans

A disadvantage of MRI is it’s higher cost compared to a regular x-ray or CAT scan.

The Magnetic Fields used by MRI’s are about 1 million times stronger than the Earth’s field.So beware funny things can happen when these machines are switched on !

Also, muscles, ligaments and tendons are seen quite well so that MRI scans are commonly used to look at knees and shoulders following injuries.

Brain

Neck

Kidneys

Knee MRIColour Enhanced

MRI scanners are good at looking at the non-bony parts or "soft tissues" of the body.In particular, the brain, spinal cord and nerves are seen much more clearly with MRI than with regular x-rays and CAT scans.

An advantage of MRI is the radio waves used are a trillion times less energetic (and potentially less damaging) than X rays.

Chapter 9

Image Interpretation

9.1 Image Interpretation: X Rays

Bullet lodged in shoulder

Broken Ulna Bone in forearm

Coin lodged in child’s oesophageus

Needle in child’s foot

9.2 Image Interpretation:CT Scans

Brain Scan Liver ScanCuts due to MVA

Brain Scan

Sub Dural Haematoma – Bleeding inside skull due to head injury from MVA

Calf (Lower Leg) Scan

DVT (Deep Vein Thrombosis)Economy Class Syndrome

Stroke – Bleeding into brain

9.3 Image Interpretation:MRI

Brain Scan

Breast Scan

Knee Scan

Heart Scan Movie

Brain Tumor

Spinal Scan

Actual Colour Enhanced

Ruptured Disc

Breast Cancer

Ruptured Cruciate Ligaments

9.4 Image Interpretation:PET Scans

These days, scans are “colour coded” making them much easier to “read”.

Brain Scan Brain scan – growing child

Shows the remarkable increase in brain activity during the 1st year of life

Resting Brain

Scans comparing brain activity during various activities with the same brain in its resting state.

Whole Body Scan

Dark Spots are cancers

9.5 Image Interpretation:Ultrasound

3-D scan of fetus with a Clubfoot

Twins shown in colour enhanced scan

Information sources:•Uranium Information Centre (UIC)•ANSTO•www.sciencephoto.com/htm•www.nlm.nih.gov/•www.spine-inc.com/•www.epub.org •www.cancer-therapy-options.com Ollie Leitl 2009