Medical physics in the electromagnetic · PDF fileRadio Waves: Mobile Phones Mobile phones use microwave energy. We know that microwaves can cook food – can a mobile phone cause

Medical physics in the electromagnetic spectrum

Radio Waves: Mobile Phones


Mobile phones use microwave energy. We know that microwaves can cook food – can a mobile phone cause heating?


0.2°C temperature rise

Infrared: Near Infrared Spectroscopy

Infrared: Pulse oximetry

Heart rate:81 bpm

Blood oxygenation: 99%



Time (seconds)

-10 0 10 20 30 40 50

Δ c

once

ntra

tion

(μm

olar

.cm

)

-4

-2

0

2

4

6

8

HbO2HbvolHb


Flashing lights

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 pillOn 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 EndoscopyAnother 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: 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 broke!)

X-rays: Computed tomography image (CT scan)

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 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


A linear accelerator generates x-rays. It rotates around the body, irradiating the tumour

from all directions


X-ray CT scan of chest shows lungs, heart and tumour (red)


A medical physicist decides which angles to shine x-rays fromto destroy tumour and minimise damage to other tissue


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)


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.

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Medical physics in the electromagnetic · PDF fileRadio Waves: Mobile Phones Mobile phones use microwave energy. We know that microwaves can cook food – can a mobile phone cause