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Medical physics in the electromagnetic spectrum
Medical physics in the electromagnetic spectrum
Radio Waves: Mobile Phones
Radio Waves: Mobile Phones
Mobile phones use microwave energy. We know that microwaves can cook food – can a mobile phone cause heating?
Radio Waves: Mobile Phones
0.2C temperature rise
Infrared: Near Infrared Spectroscopy
Infrared: Pulse oximetry
Heart rate:81 bpm
Blood oxygenation: 99%
Infrared: Near Infrared Spectroscopy
Infrared: Near Infrared Spectroscopy
Time (seconds)
-10 0 10 20 30 40 50
co
nce
ntr
atio
n ( m
ola
r.cm
)
-4
-2
0
2
4
6
8
HbO2Hbvol
Hb
Infrared: Near Infrared Spectroscopy
Flashing lights
Infrared: Thermography
Infrared: Thermography
Infrared: Thermography
Infrared: Thermography
Visible: Endoscopy
Visible: Endoscopy
Visible: Endoscopy
Visible: Endoscopy
ParasiticWorm!
The stomach wall hasrelapsed back
into the oesophagus.This is a hernia.
This is the endoscope comingout of the oesophagus
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.
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.
Visible: Scanning laser ophthalmoscope
Visible: Scanning laser ophthalmoscope
Visible: Scanning laser ophthalmoscope
Visible: Photodynamic therapy
Visible: Photodynamic therapy
Blue: Treatment of jaundice
Blue: Blue light treatment of jaundice in babies
X-rays: X-radiography
X-rays: x-radiography
X-rays: Computed tomography image (CT scan)
Secondmetatarsal bone
(the bone thatDavid Beckham and
Wayne Rooney broke!)
X-rays: Computed tomography image (CT scan)
X-rays: Radiotherapy
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
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
X-rays: Radiotherapy
A linear accelerator generates x-rays. It rotates around the body, irradiating the tumour
from all directions
X-rays: Radiotherapy
X-ray CT scan of chest shows lungs, heart and tumour (red)
X-rays: Radiotherapy
A medical physicist decides which angles to shine x-rays fromto destroy tumour and minimise damage to other tissue
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)
X-rays: Radiotherapy
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
Medical physics in the electromagnetic spectrum
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.
