HSC Physics. Module 9.6. Medical Physics

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1 HSC Physics Module 9.6 Medical Physics

2 Contextual Outline 9.6 Medical Physics (28 indicative hours) 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. Concept Map Acoustic Impedance Piezoelectri c Effect Doppler Effect Soft X-Rays Hard Reflection Ultrasound Imaging CAT Scans Refraction Bone Density Scans Sector Endoscopy Optical Fibre A Scans B Scans Phase PET Scans Radioactive Decay Nuclear Spin MRI Precessin g Larmor frequency Radio pulses & relaxation

3 Medical Physics Module Plan Module Length: 7 weeks Focus Area Time Concept Text Summary 1. The properties 1 1. identify the differences between Excel: of ultrasound ultrasound and sound in normal waves can be used hearing range p.310 as diagnostic tools 2. The physical properties of electromagnetic radiation can be used as diagnostic tools 1 2. describe the piezoelectric effect and the effect of using an alternating potential difference with a piezoelectric crystal 1 3. define acoustic impedance: Z = and identify that different materials have different acoustic impedances 1 4. describe how the principles of acoustic impedance and reflection and refraction are applied to ultrasound 1 5. define the ratio of reflected to initial intensity as: I r Z Z 2 1 I o Z 2 Z identify that the greater the difference in acoustic impedance between two materials the greater the reflected proportion of the incident pulse 1 7. 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 1 8. describe the Doppler effect in sound waves and how it is used in ultra sonics to obtain flow characteristics of blood moving through the heart 1 9. outline some cardiac problems that can be detected through the use of the Doppler effect 1 1. describe how X-rays are currently produced 1 2. compare the differences between soft and hard X-rays 1 3. explain how a computed axial tomography (CAT) scan is produced p.311 p p Excel: p Practical 1. (Act 1) 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 2. (Act 2) Identify data sources, gather, process and analyse information to describe how ultrasound is used to measure bone density 3. (Act 3) Solve problems and analyse information using: Z = and I r Z Z 2 1 I o Z 2 Z 1 4. (Act 4) Gather secondary information to observe at least two ultrasound images of body organs 5. (Act 5) Identify data sources and gather information to observe the flow of blood through the heart from a Doppler ultrasound video image 1. (Act 6) Gather information to observe at least one image of a fracture on an X-ray film and X-ray images of other body parts

4 Focus Area Time Concept Text Summary 1 4. describe circumstances where a CAT scan would be a superior diagnostic tool compared to either X-rays or ultrasound 3. Radioactivity can be used as a diagnostic tool 4. The magnetic field produced by particles can be used as a diagnostic tool 1 5. explain how an endoscope works in relation to total internal reflection 1 6. discuss differences between the role of coherent and incoherent bundles of fibres in an endoscope 1 7. explain how an endoscope is used in: observing internal organs obtaining tissue samples of internal organs for further testing 1 1. outline properties of radioactive isotopes and their half lives that are used to obtain scans of organs 1 2. describe how radioactive isotopes may be metabolised by the body to bind or accumulate in the target organ 1 3. identify that during decay of specific radioactive nuclei positrons are given off 1 4. discuss the interaction of electrons and positrons resulting in the production of gamma rays 1 5. describe how positron emission tomography (PET) technique is used for diagnosis 1 1. identify that the nuclei of certain atoms and molecules behave as small magnets 1 2. identify that protons and neutrons in the nucleus have properties of spin and describe how net spin is obtained 2 3. explain that the behaviour of nuclei with a net spin, particularly hydrogen, is related to the magnetic field they produce 2 4. describe the changes that occur in the orientation of the magnetic axis of nuclei before and after the application of a strong magnetic field Fibre Optics p. 36 The Light Fantastic p. 19 Excel: pp pp pp Maps of the Mind p.16 Rescuing Minds from disease & decay p. 29 Excel: Slicing Through Fat p.14 pp Practical 2. (Act 7) Gather secondary information to observe a CAT scan image and compare the information provided by CAT scans to that provided by an X-ray image for the same body part. 3. (Exp 8) Perform a first-hand investigation to demonstrate the transfer of light by optical fibres. 4. (Act 9) Gather secondary information to observe internal organs from images produced by an endoscope 1. (Exp 10) Perform an investigation to compare an image of bone scan with an X-ray image. 2. (Act 11) Gather and process secondary information to compare the scanned image of at least one healthy body organ with its diseased counterpart 1. (Exp 12) Perform an investigation to observe images from magnetic resonance image (MRI) scans, including a comparison of healthy and damaged tissue 2. (Act 13) Identify data sources, gather, process and present information using available evidence to explain why MRI scans can be used to: detect cancerous tissues identify areas of high blood flow distinguish between grey and white matter in the brain 3. (Act 14) Gather and process secondary information to identify the function of the electromagnet, radio frequency oscillator, radio receiver and the computer in the MRI equipment 4. (Act 15) Identify data sources, gather and process information to compare the advantages and disadvantages of X-rays, CAT scans, PET scans and MRI scans.

5 Focus Area Time Concept Text Summary 1 5. define precessing and relate the frequency of the precessing to the composition of the nuclei and the strength of the applied external magnetic field 1 6. discuss the effect of subjecting precessing nuclei to pulses of radio waves 1 7. explain that the amplitude of the signal given out when precessing nuclei relax is related to the number of nuclei present 2 8. explain that large differences would occur in the relaxation time between tissue containing hydrogen bound water molecules and tissues containing other molecules Computer Chaos at medicine s cutting edge p. 24 Practical 5. (Act 16) Gather, analyse information and use available evidence to assess the impact of medical applications of physics on society

6 HSC Physics E2: Medical Physics Activity 1: Acoustic Impedance Aim: To 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. Fill in the missing parts of the table below: Material Density (kg/m 3 ) Velocity v (m/s) Acoustic Impedance Z (X 10 6 rayls) Air Water (50 C) Fat Brain Blood Kidney Liver Muscle Lens of eye Skull HSC Physics E2: Medical Physics Activity 2: Bone Density Ultrasound Aim: To identify data sources, gather, process and analyse information to describe how ultrasound is used to measure bone density Write a 400 word report on this issue, including relevant diagrams. A bibliography must be included and in-text referencing used. Internet search words: ultrasound & education & bone HSC Physics E2: Medical Physics Activity 3: Acoustic Impedance Problems Aim: To Solve problems and analyse information using: Z = and I r Z Z 2 1 I o Z 2 Z 1 Using the values you obtained in activity 1, calculate the ratio of reflected intensities at the following boundaries: 1. air/lens 2. fat/kidney 3. blood/brain 4. muscle/skull 5. blood/liver 6. water/blood

7 HSC Physics E2: Medical Physics Activity 4: Ultrasound Images of Body Organs Aim: To gather secondary information to observe at least two ultrasound images of body organs Use the internet to obtain at least two ultrasound images of body organs. Internet search words: ultrasound & education & organ HSC Physics E2: Medical Physics Experiment 5: The Doppler Effect Aim: To identify data sources and gather information to observe the flow of blood through the heart from a Doppler ultrasound video image. Use the internet to obtain at least two videos of Doppler ultrasounds 4. Record the sites 5. Print some frames of the video and paste them into your workbook. 6. Fully label the images. Internet search words: ultrasound & Doppler & video HSC Physics E2: Medical Physics Activity 6: X-ray Images Aim: To gather information to observe at least one image of a fracture on an X-ray film and X-ray images of other body parts Use the internet to obtain at least one fracture X-ray and three other X-ray images. Internet search words: X-ray & education & fracture

8 HSC Physics E2: Medical Physics Activity 7: CAT Scans Aim: To gather secondary information to observe a CAT scan and compare the information provided by CAT scans to that provided by X-rays for the same body part. Use the internet to obtain a CAT scan and X-ray of the same site on the same person. 4. Write a 100 word report comparing the CAT scan to the X-ray. Internet search words: tomography & X-ray & scan, HSC Physics E2: Medical Physics Experiment 8: Optical Fibres Aim: To perform a first-hand investigation to demonstrate the transfer of light by optical fibres Materials Optical fibre Light source Method 1. Attach the optical fibre to the light source. 2. View the end of the optical fibre when the optical fibre is (a) straight. (b) bent. Discussion 1. Using the concept of critical angle, explain why the light does not normally escape the optical fibre. 2. Under what conditions does light escape the optical fibre?

9 HSC Physics E2: Medical Physics Activity 9: Endoscopy Aim: To gather secondary information to observe internal organs from the video images produced by an endoscope Use the internet to obtain a video image of body organs using an endoscope. 2. View the video. 3. Print some images and paste them into your workbook. 4. Fully label the images. Internet search words: endoscope & education & video, HSC Physics E2: Medical Physics Experiment 10: Bone Scans Aim: To perform an investigation to compare a bone scan with an X-ray image. Method Observe the images supplied on the disk. 1. What areas are shown by the (a) bone scan? (b) X-ray? 2. How is the technique of a bone scan different to that of an X-ray? 3. What is meant by real time imaging? Why is it important in some conditions?

10 HSC Physics E2: Medical Physics Activity 11: Scans in Disease Aim: To gather and process secondary information to compare the scan of at least one healthy body organ with its diseased counterpart Use the internet to obtain a scan image of a healthy and diseased body organ. 4. Write a 200 word report comparing the healthy and diseased images. Internet search words: scan & disease HSC Physics E2: Medical Physics Experiment 12: MRI Aim: To perform an investigation to observe magnetic resonance image (MRI) scans, including a comparison of healthy and damaged tissue Use the internet to obtain a MRI image of a healthy and diseased (preferably cancerous) body organ. Internet search words: MRI & education HSC Physics E2: Medical Physics Activity 13: Using MRI Aim: To 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 Use the internet to obtain MRI images of cancerous tissue, blood flow and brain. 4. Write a 200 word report explaining how MRI can be used to identify cancerous tissue, areas of high blood flow and differences between grey and white matter in the brain. Internet search words: MRI & brain, MRI & blood, MRI & cancer

11 HSC Physics E2: Medical Physics Activity 14: Components of MRI Equipment Aim: To 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 On a large diagram of a MRI device, label and describe 1. The electromagnet 2. The radio frequency oscillator 3. The radio receiver 4. The computer A bibliography must be included and in-text referencing used. HSC Physics E2: Medical Physics Activity 15: Comparison of Imaging Techniques Aim: To identify data sources, gather and process information to compare the advantages and disadvantages of X- rays, CAT scans, PET scans and MRI scans. Write a 500 word report on this issue, including relevant diagrams. A bibliography must be included and in-text referencing used. HSC Physics E2: Medical Physics Activity 17: Medical Applications of Physics Aim: To gather, analyse information and use available evidence to assess the impact of medical applications of physics on society Write a 500 word report on this issue, including relevant diagrams. A bibliography must be included and in-text referencing used.

Syllabus References. Resources. Video: MRI Introduction

Syllabus References. Resources. Video: MRI Introduction MRI Lesson Outline Syllabus References 9.6.4.2.5 Define precessing and relate the frequency of the precessing to the composition of the nuclei and the strength of the applied external magnetic field 9.6.4.2.6