1.   The properties of ultrasound waves can be used as diagnostic tools

Students learn to:

•     describe the properties and production of ultra sound and compare it to sound in normal hearing range

•     describe the piezoelectric effect and the effect of using an alternating potential difference with a piezoelectric crystal

•     define acoustic impedance:

      and identify that different materials have different acoustic impedances

•     describe how the principles of acoustic impedance and reflection and refraction are applied to ultrasound

•     identify that the ratio of reflected to initial intensity is:

•     explain that the greater the difference in acoustic impedance between two materials the greater the reflected proportion of the incident pulse

•     describe the situations in which A scans, B scans and phase and sector scans would be used and the reasons for the use of each

•     describe the Doppler
effect with respect to sound and how it is used in ultra sonics to obtain flow characteristics of blood flow through the heart

•     outline some cardiac problems that can be detected through the use of the Doppler effect

Students:

•    solve problems and analyse information to calculate the acoustic impedance of a range of materials, including bone, muscle, soft tissue, fat, blood and air and explain
the types of tissues that ultrasound can be used
to examine

•    gather secondary information to observe at least two ultrasound images of
body organs

•    identify data sources and gather information to observe the flow of blood through the heart from a Doppler ultrasound video image

•    identify data sources, gather, process and analyse information to describe how ultrasound is used to measure bone density

•    solve problems and analyse information using:

      and

•    identify data sources, plan, chose equipment or resources for, and perform a first-hand investigation to demonstrate the Doppler effect

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

Students learn to:

•    describe how X-rays are currently produced

•    compare the differences between ‘soft’ and ‘hard’ X-rays

•    explain how a computed axial tomography (CAT) scan is produced

•    describe circumstances where a CAT scan would be a superior diagnostic tool compared to either X-rays
or ultrasound

•    explain how an endoscope works in relation to total internal reflection

•    discuss differences between the role of coherent and incoherent bundles of fibres in an endoscope

•    explain why different types of optical fibres will affect the image produced by an endoscope

•    explain how an endoscope is used in:

     –     observing internal organs

     –     obtaining tissue samples
       of internal organs for
       further testing

Students:

•    gather information to observe at least one image of a fracture on an X-ray film and X-ray images of other body parts

•    gather secondary information to observe a CAT scan and compare the information provided by CAT scans to that provided by X-rays

•    perform a first-hand investigation to observe the transfer of light by optical fibres

•    gather secondary information to observe internal organs from the video images produced by an endoscope

3. Radioactivity can be used as a diagnostic tool

•    outline properties of radioactive isotopes and their half lives

•    identify radioisotopes that are used to obtain scans of organs

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

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

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

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

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

•    gather and process secondary information to compare the scan of at least one healthy body organ with its diseased counterpart

4.   The magnetic field produced by particles can be used as a diagnostic tool

Students learn to:

•    identify that the nuclei of certain atoms and molecules behave as small magnets

•    identify that protons and neutrons in the nucleus have properties of spin and describe how net spin is obtained

•    explain that the behaviour
of nuclei with a net spin, particularly hydrogen, is related to the magnetic field they produce

•    describe the changes that occur in the orientation of the magnetic axis of nuclei before and after the application of a strong magnetic field

•    define precessing and relate the frequency of the precessing, ie Larmor frequency, to the composition of the nuclei and the strength of the applied external magnetic field

•    discuss the effect of subjecting precessing nuclei to pulses of radio waves

•    explain that the amplitude
of the signal given out when precessing nuclei relax is related to the number of nuclei present

•    explain that large differences would occur in the relaxation time between tissue containing hydrogen bound water molecules and tissues containing other molecules

Students:

•    perform an investigation to observe magnetic resonance image (MRI) scans, including a comparison of healthy and cancerous tissue

•    identify data sources, gather, process and present information using available evidence to explain why MRIs can be used to:

      –    detect cancerous tissues

      –    identify areas of high
      blood flow

      –    distinguish between grey
      and white matter in
      the brain

•    gather and process secondary information to identify the function of the electromagnet, the radio frequency oscillator, the radio receiver and the computer in the MRI equipment

•    identify data sources, gather and process information to compare the advantages and disadvantages of X-rays, CAT scans, PETs and MRIs

•           gather, analyse information and use available evidence to assess the impact of medical applications of physics on society