medical physics option 9.6.3 2006 option 9.6.3 2006

Medical PhysicsMedical Physics

Option 9.6.32006

Option 9.6.32006

Syllabus - Contextual OutlineSyllabus - Contextual Outline

Contextual Outline

The use of other advances in technology, developed from our understanding of the electromagnetic spectrum, and based on sound physical principles, has allowed medical technologists more sophisticated tools to analyse and interpret bodily process for diagnostic purposes. Diagnostic imaging expands the knowledge of practitioners and the practice of medicine. It usually uses non-invasive methods for identifying and monitoring diseases or injuries via the generation of images representing internal anatomical structures and organs of the body.Technologies, such as ultrasound, compute axial tomography, positron emission tomography and magnetic resonance imaging, can often provide clear diagnostic pictures without surgery. A magnetic resonance image (MRI) scan of the spine, for example, provides a view of the discs in the back, as well as the nerves and other soft tissues. The practitioner can look at the MRI films and determine whether there is a pinched nerve, a degenerative disc or a tumour. The greatest advantage of these techniques are their ability to allow the practitioner to see inside the body without the need for surgery.This module increases students’ understanding of the history of physics and the implications of physics for society and the environment.

Contextual Outline

The use of other advances in technology, developed from our understanding of the electromagnetic spectrum, and based on sound physical principles, has allowed medical technologists more sophisticated tools to analyse and interpret bodily process for diagnostic purposes. Diagnostic imaging expands the knowledge of practitioners and the practice of medicine. It usually uses non-invasive methods for identifying and monitoring diseases or injuries via the generation of images representing internal anatomical structures and organs of the body.Technologies, such as ultrasound, compute axial tomography, positron emission tomography and magnetic resonance imaging, can often provide clear diagnostic pictures without surgery. A magnetic resonance image (MRI) scan of the spine, for example, provides a view of the discs in the back, as well as the nerves and other soft tissues. The practitioner can look at the MRI films and determine whether there is a pinched nerve, a degenerative disc or a tumour. The greatest advantage of these techniques are their ability to allow the practitioner to see inside the body without the need for surgery.This module increases students’ understanding of the history of physics and the implications of physics for society and the environment.

Syllabus 9.6.1Syllabus 9.6.1The properties of ultrasound waves can be used as diagnostic tools

The properties of ultrasound waves can be used as diagnostic tools

Syllabus 9.6.2Syllabus 9.6.2

The physical properties of electromagnetic radiation can be used as diagnostic tools

The physical properties of electromagnetic radiation can be used as diagnostic tools


Radioactivity can be used as a diagnostic toolRadioactivity can be used as a diagnostic tool


The magnetic fieldproduced bynuclear particlescan be used as adiagnostic tool

The magnetic fieldproduced bynuclear particlescan be used as adiagnostic tool

MedicalPhysics

Ultrasound X-rays

Nuclear - PET

MRI

Endoscopy

Individual1 minute

Individual1 minute

Group2 minutes

Group2 minutes


Radioactivity can be used as a diagnostic toolRadioactivity can be used as a diagnostic tool

Radioactive Isotopes and Half-livesRadioactive Isotopes and Half-lives

The atom

• Electrons

• Nucleus• Protons

• neutrons• Quarks

The atom

• Electrons

• Nucleus• Protons

• neutrons• Quarks

• outline properties of radioactive isotopes and their half lives that are used to obtain scans of organs

Radioactive IsotopesRadioactive Isotopes

• Atomic nuclei contain protons and neutrons

• The number of protons in the nucleus is called the atomic number

• The atomic number determines which element an atom is e.g. all fluorine atoms have 9 protons in the nucleus

• The number of neutrons in the nucleus of a particular element can vary

• Atomic nuclei contain protons and neutrons

• The number of protons in the nucleus is called the atomic number

• The atomic number determines which element an atom is e.g. all fluorine atoms have 9 protons in the nucleus

• The number of neutrons in the nucleus of a particular element can vary


Atoms of the same element but with different numbers of neutrons are

called isotopes

Only hydrogen has isotopes with

special names

The atomic nucleus and isotopesThe atomic nucleus and isotopes

• Collectively, protons and neutrons are called nucleons

• The total number of nucleons in a nucleus is called the mass number

• Nuclei are represented by the symbol for the element, and the mass and atomic numbers

• Atoms of the same element but having different numbers of neutrons are called isotopes

• Collectively, protons and neutrons are called nucleons

• The total number of nucleons in a nucleus is called the mass number

• Nuclei are represented by the symbol for the element, and the mass and atomic numbers

• Atoms of the same element but having different numbers of neutrons are called isotopes


technetium 99

Tc 99 43

F 18 9

fluorine 18

mass number

atomic number

Stable and unstable isotopesStable and unstable isotopes

• Isotopes having too many or too few neutrons, relative to the number of protons are unstable

• Isotopes having too many or too few neutrons, relative to the number of protons are unstable


C

14 6

unstable nucleus

stable nucleus

F 19 9

F 18 9

unstable nucleus

Radioactive DecayRadioactive Decay

• Unstable isotopes may become more stable in several ways

• Alpha decay (decay)• Beta decay (decay)• Gamma () emission• Positron emission (+ decay)

• Each unstable isotope undergoes a particular type of change, which is on average constant and unique to that isotope



• Each unstable isotope undergoes a particular type of change, which is on average constant and unique to that isotope


RadioisotopesRadioisotopes

• Radioisotopes may be natural or they can be artificial

• Artificial radioisotopes are produced in nuclear reactors or using particle accelerators called cyclotrons

• Sydney has one medical cyclotron at Prince Alfred Hospital near Sydney University

• Lucas Heights produces a range of artificial isotopes for medical use

• Radioisotopes may be natural or they can be artificial

• Artificial radioisotopes are produced in nuclear reactors or using particle accelerators called cyclotrons

• Sydney has one medical cyclotron at Prince Alfred Hospital near Sydney University

• Lucas Heights produces a range of artificial isotopes for medical use


RadioisotopesRadioisotopes




• The time taken for 50% of a sample of the radioactive material to decay is called the half-life

• The time taken for 50% of a sample of the radioactive material to decay is called the half-life



Half-life Alpha decay of phosphorus-210

128

73

41.9

23.9

13.77.8

4.480

20

40

60

80

100

120

140

0 20 40 60 80

time (s)

Time (s) Mass (g)0 128

10 7320 41.930 23.940 13.750 7.860 4.48

12 sP-210 has a half-life of 12 seconds

Review Question - Half-lifeReview Question - Half-life

What is the half-life of strontium-90?What is the half-life of strontium-90?

28 years



When beta decay occurs, a neutron in the nucleus changes into a proton (which remains in the nucleus) and an electron (which is ejected from the nucleus at high velocity).

In all nuclear reactions, mass and charge are conserved.

Propose what may happen in the nucleus to produce positron emission.

AnswerA proton changes into a positron and a neutron, which remains in the nucleus and the positron is ejected from the nucleus.

When beta decay occurs, a neutron in the nucleus changes into a proton (which remains in the nucleus) and an electron (which is ejected from the nucleus at high velocity).

In all nuclear reactions, mass and charge are conserved.

Propose what may happen in the nucleus to produce positron emission.

AnswerA proton changes into a positron and a neutron, which remains in the nucleus and the positron is ejected from the nucleus.


Decay producing a gamma rayDecay producing a gamma ray

• Gamma decay does not change either the atomic number or the mass number

• The nucleus is left in a lower energy state as a result of losing energy in the form of gamma radiation

• Gamma rays are very important in nuclear medicine

• Gamma decay does not change either the atomic number or the mass number

• The nucleus is left in a lower energy state as a result of losing energy in the form of gamma radiation

• Gamma rays are very important in nuclear medicine


Technetium-99m nucleus

Radioactive Isotopes and Half-livesRadioactive Isotopes and Half-lives


Beta+ Decay of Artificial IsotopesBeta+ Decay of Artificial Isotopes

• Positron (+) decay occurs only in certain man-made isotopes• + decay is medically very important (used in the process of PET scanning)• Positrons are anti-electrons• Positrons have the same mass as an electron, but the opposite charge (+1)

• Positron (+) decay occurs only in certain man-made isotopes• + decay is medically very important (used in the process of PET scanning)• Positrons are anti-electrons• Positrons have the same mass as an electron, but the opposite charge (+1)


Penetration by RadiationPenetration by Radiation


ReviewReview

1. Define the term “isotope”.2. Outline the characteristic of an

isotope that causes it to be unstable and give an example of an element having stable and unstable isotopes.

3. Technetium-99 is an important medical isotope. Identify the type of radiation produced when Tc-99 decays.

4. Fluorine-18 decays to produce a positron. Describe the main characteristics of positrons and identify the other main decay product from F-18.

1. Define the term “isotope”.2. Outline the characteristic of an

isotope that causes it to be unstable and give an example of an element having stable and unstable isotopes.

3. Technetium-99 is an important medical isotope. Identify the type of radiation produced when Tc-99 decays.

4. Fluorine-18 decays to produce a positron. Describe the main characteristics of positrons and identify the other main decay product from F-18.

1. Isotopes are atoms of the same element, having different numbers of neutronse.g. carbon-12 and carbon-14

2. Unstable isotopes are characterised by having too many or too few neutrons, relative to the number of protons. e.g. F-19 is stable however F-18 is unstable.

3. Tc-99 produces gamma radiation when it decays.

4. Positrons have the same mass as an electron but the same positive charge as a proton. When F-18 decays to produce a positron, an oxygen-18 nucleus is produced.

1. Isotopes are atoms of the same element, having different numbers of neutronse.g. carbon-12 and carbon-14

2. Unstable isotopes are characterised by having too many or too few neutrons, relative to the number of protons. e.g. F-19 is stable however F-18 is unstable.

3. Tc-99 produces gamma radiation when it decays.

4. Positrons have the same mass as an electron but the same positive charge as a proton. When F-18 decays to produce a positron, an oxygen-18 nucleus is produced.

Properties of Radioactive IsotopesProperties of Radioactive Isotopes


Alpha: highly ionising (high mass and charge), low penetration

Not used medically

Beta: less ionising (low mass and single charge), low penetration

Not used medically

Gamma: least ionising (photon, no charge), high penetration

Used for imaging (gamma scan)

Properties of Radioactive IsotopesProperties of Radioactive Isotopes


Source: ANSTO brochure

Metabolism of Isotopes - Organ AccumulationMetabolism of Isotopes - Organ Accumulation

• describe how radioactive isotopes may be metabolised by the body to bind or accumulate in the target organ



• Medical radioisotopes are metabolised to bind to specific organs either as elements or as a part of a molecule used by the body

e.g.

• iodine-131 is used to monitor thyroid gland function because iodine is metabolised by this gland

• Iodine-131 decays with a half-life of 8.0197 days with beta and gamma emissions

• fluorine-18 is incorporated into a modified glucose (18 FDG) molecule to investigate a wide range of organ function, especially the brain

• Medical radioisotopes are metabolised to bind to specific organs either as elements or as a part of a molecule used by the body

e.g.

• iodine-131 is used to monitor thyroid gland function because iodine is metabolised by this gland

• Iodine-131 decays with a half-life of 8.0197 days with beta and gamma emissions

• fluorine-18 is incorporated into a modified glucose (18 FDG) molecule to investigate a wide range of organ function, especially the brain




Factors influencing the choice of isotopes for medical use

• Half-life should be less than a few hours• Should be easily attached to a pharmaceutical agent• Can be delivered to hospital in a form to last several days

Factors influencing the choice of isotopes for medical use

• Half-life should be less than a few hours• Should be easily attached to a pharmaceutical agent• Can be delivered to hospital in a form to last several days



• Technetium-99m is a widely-used isotope in nuclear medicine

• It decays from excited to the ground state by emitting a ray• The parent isotope is molybdenum 99, having a half-life of 2.7 days

• Half-life of technetium-99m is 6.01 hours

• Technetium-99m is a widely-used isotope in nuclear medicine

• It decays from excited to the ground state by emitting a ray• The parent isotope is molybdenum 99, having a half-life of 2.7 days

• Half-life of technetium-99m is 6.01 hours


4299

4399Mo Tcm

4399 Tc Tc + (140 keV)m

4399

Half life 2.7 days

Half life 6.01 hours

Milking the CowMilking the Cow


• Molybdenum-99 is delivered to hospital inside the generator (cow)

• Decays to the excited state of technetium 99• NaCl solution passed through cow• 99Tcm removed in solution• Mixed with pharmaceutical for labelling• Injected into patient

RadionuclideRadionuclide

generatorgenerator

RadionuclideRadionuclide

generatorgenerator

Comparison of Bone Scan and X-ray ImagesComparison of Bone Scan and X-ray Images

• Inject patient with radiopharmaceutical labelled with radioactive isotope

• Detect where gamma rays are coming from within the body

• Use a gamma camera• Local concentration in patient permits

diagnosis• ‘Hotspot’ may indicate tumour*

• Inject patient with radiopharmaceutical labelled with radioactive isotope

• Detect where gamma rays are coming from within the body

• Use a gamma camera• Local concentration in patient permits

diagnosis• ‘Hotspot’ may indicate tumour*

• perform an investigation to compare an image of bone scan with an X-ray image

* Tumours contain rapidly dividing cells… therefore metabolism occurs at a higher rate in the tumour… producing a higher than normal concentration of metabolites, in the cells. If tagged with radioisotopes this can be detected.


• Collimator restricts direction from which photons reach the camera

• Made of lead with parallel holes running through it

• Bigger, shorter holes means more photons, but more blurring and visa versa

• Collimator restricts direction from which photons reach the camera

• Made of lead with parallel holes running through it

• Bigger, shorter holes means more photons, but more blurring and visa versa

Details need not be memorised

Gamma cameraGamma camera



• Detector made from single crystal of sodium iodide• 250 mm to 250 mm diameter• 6 mm thick• Enveloped in thin aluminium can

(light tight)• Light guide takes all light directly to

photomultipliers• Glass plate with non-reflective

coating• Improves efficiency of light

coupling

• Detector made from single crystal of sodium iodide• 250 mm to 250 mm diameter• 6 mm thick• Enveloped in thin aluminium can

(light tight)• Light guide takes all light directly to

photomultipliers• Glass plate with non-reflective

coating• Improves efficiency of light

coupling


Delivery of Radioisotopes into the BodyDelivery of Radioisotopes into the Body

• Radioisotopes are usually injected* into the body

• Short half-life isotopes are used to reduce risk

• Isotopes that are excreted rapidly are used

• Specific isotopes are chosen specific organs

* sometimes they are inhaled or swallowed

Delivery of Radioisotopes into the BodyDelivery of Radioisotopes into the Body

Whole body bone scan made using a gamma ray camera. The image was produced using gamma emissions from phosphate tagged with technetium–99m.

The tracer was injected intravenously and the phosphate is metabolised mainly in the bones.

The test was done to determine whether cancer had spread to the patient’s bones.

The image is normal, showing that metastasis has not occurred.

Whole body bone scan made using a gamma ray camera. The image was produced using gamma emissions from phosphate tagged with technetium–99m.

The tracer was injected intravenously and the phosphate is metabolised mainly in the bones.

The test was done to determine whether cancer had spread to the patient’s bones.

The image is normal, showing that metastasis has not occurred.

Bone Scan vs X-RayBone Scan vs X-Ray


Comparison of Diseased and Healthy OrgansComparison of Diseased and Healthy Organs

Similarities• Both x-ray and bone scans (gamma or PET) use high energy electromagnetic waves to

produce the image• Both types of image show 3-dimensions projected onto a 2-dimensional imageDifferences• A radiograph uses x-ray radiation whereas a bone scan uses gamma radiation• The source of x-rays for a radiograph is outside the body whereas the source of gamma

rays for a bone scan is inside the body• A radiograph has a higher resolution than a bone scan image [due to the need to use a

collimator for the bone scan]• A radiograph is a produces an image that shows structure whereas a bone scan produces

an image resulting from functional differences (difference in metabolism - which may reflect structural differences)

Question

Compare a bone scan with an X-ray.




What caused this hot spot?

• gather and process secondary information to compare a scanned image of at least one healthy body part or organ with a scanned image of its diseased counterpart

Answer

The radioactive tracer was injected into the vein in the arm.

Traces of the radioactive material remain at the injection site.



Bone scan

Recount how a bone scan is produced.

Answer

1. A radiopharmaceutical is put in the patient by injection, inhalation or ingestion. The patient waits while the radiopharmaceutical is metabolised. The radioisotope accumulates in the target organ.

2. The patient lies down and remains stationary on or under a gamma camera.

3. Gamma rays are emitted in all directions from the body, however the collimator allows only gamma rays following parallel paths to reach the gamma detector in the camera.

4. Signals from the detector are processed by a computer to produce an image showing functional information.

Positron Emission Tomography (PET)Positron Emission Tomography (PET)

PET is used for• bone imaging• monitoring tumours• monitoring the function of the heart• monitoring blood-flow in the heart• studying brain activity

Overview

PET is used for• bone imaging• monitoring tumours• monitoring the function of the heart• monitoring blood-flow in the heart• studying brain activity

Overview

A radiopharmaceutical that produces positrons is placed in the body, targeting a particular organ. The radioisotope accumulates in the desired organ. Positrons are emitted into the body as the isotope decays. Positrons annihilate electrons, producing a pair of gamma rays that travel in opposite directions. The pairs of gamma rays are detected by a ring of sensors. Signals from the sensors are processed by a computer to produce an image showing the location and concentration of the radioisotope in the body. The radioactive material is excreted or decays to form harmless products.

Radioactive Decay - Positron ProductionRadioactive Decay - Positron Production

• Phosphorus-30 and fluorine-18 are two artificial radioisotopes that undergo decay that produces positrons

• As a result of the radioactive decay of fluorine-18, a positron is emitted from the nucleus

• Phosphorus-30 and fluorine-18 are two artificial radioisotopes that undergo decay that produces positrons

• As a result of the radioactive decay of fluorine-18, a positron is emitted from the nucleus

• identify that during decay of specific radioactive nuclei positrons are given off

15153030

14143030PP SiSi ++ ++

991818

881818FF OO ++

Explanation - because there are too many protons in the nucleus for it to be stable, one of the protons decays, producing a positron and a neutron which remains in the nucleus

Positron Annihilation - Gamma Ray ProductionPositron Annihilation - Gamma Ray Production

• A positron interacts with an electron, annihilating both and producing two -photons [energy = 0.511 MeV][energy = 0.511 MeV]positron + electron => gamma rays

• The -photons travel in opposite directionsGamma photons produced use in PET• Gives high resolution compared with other

gamma imaging technologies [but not as good as X-ray, CT, ultrasound, MRI]

• Typical isotopes used: 18F, 68Ga, 15O• Isotopes produced using cyclotron

• Main advantage - the image produced is a functional image i.e. it shows HOW the body is working

• A positron interacts with an electron, annihilating both and producing two -photons [energy = 0.511 MeV][energy = 0.511 MeV]positron + electron => gamma rays

• The -photons travel in opposite directionsGamma photons produced use in PET• Gives high resolution compared with other

gamma imaging technologies [but not as good as X-ray, CT, ultrasound, MRI]

• Typical isotopes used: 18F, 68Ga, 15O• Isotopes produced using cyclotron

• Main advantage - the image produced is a functional image i.e. it shows HOW the body is working

• discuss the interaction of electrons and positrons resulting in the production of gamma rays

The most commonly used tracer is 18FDG

(18F fluorodeoxyglucose)

PET ScannerPET Scanner

• describe how the positron emission tomography (PET) technique is used for diagnosis

This imaging technology is called tomography because the image is obtained and usually viewed as slices perpendicular to the long axis of the body. Because the data are analysed by a computer, it is also possible to create a computer-generated 3-D image from the scans.

Diagnosis Using PETDiagnosis Using PET


How PET Scanning is PerformedHow PET Scanning is Performed

• Contrast this with a gamma scan, which produces a 2-D image of a 3-D volume

• Similar to CT - HOW?• Many slices can be digitally

combined to produce a virtual 3-D image

• Contrast this with a gamma scan, which produces a 2-D image of a 3-D volume

• Similar to CT - HOW?• Many slices can be digitally

combined to produce a virtual 3-D image


• PET produces an image of a 2-D section through the body

• Tomography: “slice” or “section”

• PET produces an image of a 2-D section through the body

• Tomography: “slice” or “section”


• PET uses annihilation coincidence detection (ACD)!!

• Ring of gamma ray detectors around body

• Time of arrival and intensity of gamma rays is recorded

• 2 simultaneous events give line of response (LOR)

• Image is built up from LOR data

• PET uses annihilation coincidence detection (ACD)!!

• Ring of gamma ray detectors around body

• Time of arrival and intensity of gamma rays is recorded

• 2 simultaneous events give line of response (LOR)

• Image is built up from LOR data


• Positron + electron annihilate each other• Two photons are

emitted in opposite directions

• Positron + electron annihilate each other• Two photons are

emitted in opposite directions


• Positrons emitted from the tracer annihilate electrons producing gamma ray pairs

1. The gamma ray pair strikes detectors on opposite sides of the patient

2. A flash of light is produced by the detectors arranged in a circular ring

3. A computer compares the intensity of gamma ray pairs over time, and calculates the location of the positron-electron interactions to produce an image

• Positrons emitted from the tracer annihilate electrons producing gamma ray pairs

1. The gamma ray pair strikes detectors on opposite sides of the patient

2. A flash of light is produced by the detectors arranged in a circular ring

3. A computer compares the intensity of gamma ray pairs over time, and calculates the location of the positron-electron interactions to produce an image



The greater the depth of tissue through which the gamma rays travel, the greater the attenuation of the gamma rays - enabling the source point to be located by comparing intensities of gamma rays on opposite sides of the body.

The greater the depth of tissue through which the gamma rays travel, the greater the attenuation of the gamma rays - enabling the source point to be located by comparing intensities of gamma rays on opposite sides of the body.



• PET Scan• PET Scan


PET Images of the BrainPET Images of the Brain

Heart with myocardial infarction.Arrows indicate diseased tissue

Normal heart (left)

Heart with myocardial infarction.Arrows indicate diseased tissue

Normal heart (left)


PET Images of the BrainPET Images of the Brain

Brain of 9 year old girl suffering from epilepsy.

Arrow indicates problem area, which was removed.

Normal brain (left)

Brain of 9 year old girl suffering from epilepsy.

Arrow indicates problem area, which was removed.

Normal brain (left)


QuestionsQuestions

1. Identify the particle produced by radioactive decay that is used for to produce PET images. (1M)

2. Identify the radiation detected to produce a bone scan. (1M)

3. Compare the processes of taking an X-ray image to producing a PET image. (4M)

4. Compare the type of images produced using ultrasound and PET. (2M)

1. Identify the particle produced by radioactive decay that is used for to produce PET images. (1M)

2. Identify the radiation detected to produce a bone scan. (1M)

3. Compare the processes of taking an X-ray image to producing a PET image. (4M)

4. Compare the type of images produced using ultrasound and PET. (2M)

1. Positron2. Gamma rays3. The radiation source is outside the body

in the case of X-rays but it is inside the body in the case of a PET scan. Both processes use e/m radiation to produce the image; X-rays and gamma rays, however the gamma rays are produced inside the body by positron-electron annihilation whereas X-rays are produced using an X-ray tube.

4. Images produced using ultrasound are structural (showing anatomy) whereas PET produces functional images (showing physiology)

1. Positron2. Gamma rays3. The radiation source is outside the body

in the case of X-rays but it is inside the body in the case of a PET scan. Both processes use e/m radiation to produce the image; X-rays and gamma rays, however the gamma rays are produced inside the body by positron-electron annihilation whereas X-rays are produced using an X-ray tube.

4. Images produced using ultrasound are structural (showing anatomy) whereas PET produces functional images (showing physiology)

PET Images … or not?PET Images … or not?

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

A word from the creator

This PowerPoint presentation was prepared by

Greg Pittof

Hurlstone Agricultural High School

Please feel free to use this material as you see fit, but if you use substantial parts of this presentation,

leave this slide in the presentation.

Share resources with your fellow teachers and students.

Answers to QuestionsAnswers to Questions

Similarities• Both x-ray and bone scans (gamma or PET) use high energy electromagnetic waves to

produce the image• Both types of image show 3-dimensions projected onto a 2-dimensional imageDifferences• A radiograph uses x-ray radiation whereas a bone scan uses gamma radiation• The source of x-rays for a radiograph is outside the body whereas the source of gamma

rays for a bone scan is inside the body• A radiograph has a higher resolution than a bone scan image [due to the need to use a

collimator for the bone scan]• A radiograph is a produces an image that shows structure whereas a bone scan produces

an image resulting from functional differences (difference in metabolism - which may reflect structural differences)

Question

Compare a bone scan with an X-ray.

Answers to QuestionsAnswers to Questions

medical physics option 9.6.3 2006 option 9.6.3 2006

Documents

diagnostic imaging

diagnostic toolssyllabus

diagnostic toolsyllabus

diagnostic purposes

half lives

neutronsthe number of

nucleusthe number of

atomic numberthe atomic