1. Medical physics in the electromagnetic spectrum
Further information:
M C J Barker (1996) Medical imaging Phys. Educ. 31 (March 1996) 70-75
D Hart (1996) Patient radiation doses from diagnostic radiology Phys. Educ. 31 (March 1996) 75-79
D Sumner (1995) X-rays-risks versus benefits Phys. Educ. 30 (November 1995)
Greg Michael (2001) X-ray computed tomography Phys. Educ. 36 (November 2001)
Edwin Aird (1996) Radiotherapy: technical aspects and modern trends Phys. Educ. 31 (March 1996)
Mark Oldham (2001) Radiation physics and applications in therapeutic medicine Phys. Educ. 36 (November 2001)
History:
R F Mould (1995) The early history of X-ray diagnosis with emphasis on the contributions of physics Phys. Med. Biol. 40 (November 1995)
S Foulger (1995) The discovery of X-rays Phys. Educ. 30 (November 1995)
A Hessenbruch (1995) X-rays for medical use Phys. Educ. 30 (November 1995)
A Schedel (1995) An unprecedented sensation-public reaction to the discovery of X-rays Phys. Educ. 30 (November 1995)

2. Radio Waves: Mobile Phones

3. Radio Waves: Mobile Phones
Mobile phones use microwave energy. We know that microwaves can cook food – can a mobile phone cause heating?
Pictures from Gerard van Leeuwen
Needs explanation

4. Radio Waves: Mobile Phones
0.2C temperature rise
Pictures from Gerard van Leeuwen

5. Infrared: Near Infrared Spectroscopy

6. Infrared: Pulse oximetry
Heart rate:81 bpm
Blood oxygenation: 99%

7. Infrared: Near Infrared Spectroscopy
Picture from Clare Elwell
Needs explanation
Near infrared spectroscopy (NIRS)
Child observes flashing chequerboard which stimulates visual cortex, increasing blood flow. Under the black cap is a NIRS probe which emits and detects NIR light which has diffused into head.
Haemoglobin absorbs NIR light strongly. Hence, an increase in blood volume decreases the intensity of the measured signal. Moreover, the absorption spectra of oxy- and deoxy- haemoglobin differ, so measuring at two wavelengths gives a measure of oxygen saturation.

8. Infrared: Near Infrared Spectroscopy
Picture from Clare Elwell
Needs explanation

9. Infrared: Near Infrared Spectroscopy
Flashing lights
Picture from Clare Elwell
Needs explanation

10. Infrared: Thermography

11. Infrared: Thermography
Picture from Jeff Jones
Thermography – shows surface map of temperature by measuring emitted infrared light.
On left – normal hands – fingers and blood vessels appear warm
On right – Raynaud’s syndrome – reduces blood flow to fingers means they appear cold.
Next picture – similar illustration of child’s face

12. Infrared: Thermography
Picture from Jeff Jones

13. Infrared: Thermography
Picture from Jeff Jones
Thermography image of healthy back overlaid onto normal photograph.

14. Visible: Endoscopy

15. Visible: Endoscopy
Picture from Sandy Mosse

16. Visible: Endoscopy Pictures from Sandy Mosse An endoscope
An x-ray image showing an endoscope passing down the oesophagus, into the stomach (far right), then into the intestines.

17. Visible: Endoscopy Parasitic Worm! This is the endoscope coming
out of the oesophagus
The stomach wall has
relapsed back
into the oesophagus.
This is a hernia.
Parasitic
Worm!
Pictures from Sandy Mosse
Worm is in the stomach

18. Visible: Endoscopy with a camera pill
On the right is an x-ray movie showing a pill which has been swallowed which contains a camera. It passes through the gut, taking a movie which is sent to a receiver outside the body, shown on the left.
Pictures from Sandy Mosse

19. Visible: New approaches to Endoscopy
Another new method is virtual endoscopy. Here, we take a high resolution CT scan of the body using x-rays and then, using a computer, identify the gut wall and show it as if it is viewed through an endoscope.
This prevents the discomfort which patients may feel during endoscopy
This movie shows a polyp in the wall of the gut.
Pictures from Alf Linney

20. Visible: Scanning laser ophthalmoscope

21. Visible: Scanning laser ophthalmoscope
Picture from Dr. A(Mani). Manivannan, Aberdeen
Could mention use in security and biometrics
With thanks to
Dr. A Manivannan

22. Visible: Scanning laser ophthalmoscope
Picture from Dr. A(Mani). Manivannan, Aberdeen
With thanks to
Dr. A Manivannan

23. Visible: Photodynamic therapy

24. Visible: Photodynamic therapy
Picture from David Taylor
Dermatological PDT for Bowen’s disease (a kind of skin cancer). A drug called Metvix is rubbed onto the skin as a cream and it is preferentially absorbed by cancer cells. The drug therefore collects in the tumour. When the skin is then illuminated with visible light, the drug breaks down and destroys cells. The process is therefore doubly selective – first the drug collects in the tumour and second, only the tumour is illuminated.

25. Blue: Treatment of jaundice

26. Blue: Blue light treatment of jaundice in babies
Picture from Topun Austin
Premature babies sometimes have jaundice. This makes them look yellow and is due to excess bilirubin, the yellow pigment in bruises. It is usually harmless but can be treated using blue light. The blue light breaks down the bilirubin so that it can be excreted as urine.

27. X-rays: X-radiography

28. X-rays: x-radiography
Picture from Nature
First clinical x-ray taken by Wilhelm Roentgen on 22 Dec 1895, of his wife’s hand, showing wedding ring and bones of fingers.
This was taken with a 15 minute exposure; a modern x-ray image has an expose of ~10-ms (CHECK)

29. X-rays: Computed tomography image (CT scan)
Second
metatarsal bone
(the bone that
David Beckham and
Wayne Rooney broke!)
Picture from
This is a CT image which has been processed by computer so that only the bones and the muscles are shown.
The second metatarsal bone (the bone that Beckham broke) is shown.

30. X-rays: Computed tomography image (CT scan)
Picture from
Similarly, this CT image of the pelvis which has been processed so that only the bones show.

31. X-rays: Radiotherapy

32. X-rays: Radiotherapy

33. X-rays: Radiotherapy
Cancer occurs when cells divide too quickly. The dividing cells become a tumour which can damage surrounding tissue or spread to the rest of the body

34. X-rays: Radiotherapy
X-rays or other radiation can damage the DNA in cells and kill them
This is why radiation can be dangerous
But cells which are dividing rapidly are more likely to be killed
So we use x-rays to kill the rapidly-dividing cancer cells
We must still ensure that healthy tissue is undamaged

35. X-rays: Radiotherapy
A linear accelerator generates x-rays. It rotates around the body, irradiating the tumour from all directions
Image: Elekta

36. Which part has received the higher dose?

37. X-ray CT scan of chest shows lungs, heart and tumour (red)
X-rays: Radiotherapy
X-ray CT scan of chest shows lungs, heart and tumour (red)
Picture from Jeff Jones

38. X-rays: Radiotherapy
A medical physicist decides which angles to shine x-rays from
to destroy tumour and minimise damage to other tissue
Image: Elekta

39. X-rays: Radiotherapy
The treatment plan lists the directions the x-rays will come from and calculates the radiation dose to the tumour (in purple) and rest of body (grey)
Picture from

40. Summary:
Medical physicists use all parts of the electromagnetic spectrum to diagnose and treat illnesses
Different parts of the spectrum interact in different ways with the body because they have different energies
Low energy
High energy

41. Medical physics in the electromagnetic spectrum

43. Acknowledgements:
Thanks to Dr Gerard van Leeuwen, Dr Clare Elwell, Dr Kevin Howells, Dr Sandy Mosse, Dr Paul Campbell, Dr Topun Austin, Dr Alf Linney, GE Healthcare, Paul Burke and Jeff Jones, and Elekta for providing images.
This lesson was developed by Adam Gibson, Jeff Jones, David Sang, Angela Newing, Nicola Hannam and Emily Cook
We have attempted to obtain permission and acknowledge the contributor of every image. If we have inadvertently used images in error, please contact us.