Boobs, Babes and Blood

For the average physicist, you might expect typical study subjects to include atoms or distant galaxies. Visit the medical physics department at University College London however, and you’d be more likely to stumble upon premature babies or breast cancer patients in the lab.

Dr Adam Gibson and his team are developing a new medical imaging technique, known as optical tomography, which uses near infrared light to take a peek at what blood is getting up to inside the human body.

The instrument, called MONSTIR, shines light through the body and counts individual photons as they emerge at the other side. ‘Blood absorbs light very strongly,’ says Gibson. ‘So the amount of light that gets through is an indicator of the amount of blood.’

By using two different wavelengths of light and comparing how the two are absorbed, the colour of the blood - a telltale sign of its oxygen levels - can also be deduced. ‘Bright red, tomato ketchup blood carries lots of oxygen, and dull, brown blood has less,’ explains Gibson.

In itself, this is already an exciting development for medical imaging. Most imaging techniques take a snapshot of the body which then needs to be interpreted, but MONSTIR’s images provide not just pretty pictures but hard numbers.

A rush of blood to the head


Oxygenated blood fuels many processes in the body and following its path can deliver precious insight to doctors. The team at UCL has already used MONSTIR to explore what’s on the mind of premature babies. ‘The part of the brain that’s active uses more blood,’ explains Gibson. ‘So you can use this to map out brain activity.’

As well as investigating babies’ perception of pain and the way they learn language, the team have used the technique to detect bleeding inside the brain.

Breast cancer patients have also come under MONSTIR’s scrutiny. ‘Cancer is associated with an increase in blood volume to the tumour, and sometimes also changes in blood oxygenation,‘ says Gibson.

Whilst the relatively poor resolution of the images produced means the technique is not best suited to screening for cancer, it has advantages over alternative imaging techniques for other applications in the fight against cancer. In particular, MONSTIR could come in handy for monitoring the effectiveness of a particular drug which aims to starve cancer by disrupting blood flow to the tumour.

‘With x-rays, you get ionising radiation, and MRI is big, expensive and clumsy, so it’s not convenient to use it over and over again, whereas we can use this as often as we want to,’ comments Gibson.

Finding parents willing to lend their newborn babies for a day can sometimes be harder than spotting far flung planets, but Gibson wouldn’t have it any other way. ‘One of the nice things about medical physics is the patient contact. It’s nice for us to be reminded of what we’re doing our research for.’

Find related websites on medical imaging with physics.org

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