New CT scan method lowers radiation exposure

Date:
July 23, 2020
Source:
University College London
Summary:
A CT scan technique that splits a full X-ray beam into thin beamlets
can deliver the same quality of image at a much reduced radiation
dose, according to a new study. The technique, demonstrated on a
small sample in a micro CT scanner, could potentially be adapted
for medical scanners and used to reduce the amount of radiation
millions of people are exposed to each year.



FULL STORY ==========================================================================
A CT scan technique that splits a full X-ray beam into thin beamlets
can deliver the same quality of image at a much reduced radiation dose, according to a new UCL study.


==========================================================================
The technique, demonstrated on a small sample in a micro CT scanner,
could potentially be adapted for medical scanners and used to reduce
the amount of radiation millions of people are exposed to each year.

A computerised tomography (CT) scan is a form of X-ray that creates very accurate cross-sectional views of the inside of the body. It is used to
guide treatments and diagnose cancers and other diseases.

Past studies have suggested CT scans may cause a small increase in
lifelong cancer risk because their high-energy wavelengths can damage
DNA. Although cells repair this damage, sometimes these repairs are
imperfect, leading to DNA mutations in later years.

In the new study, published in Physical Review Applied, researchers
placed a mask with tiny slits over an X-ray beam, breaking up the beam
into beamlets.

They then moved the sample being imaged in a cycloidal motion that
ensured the whole object was irradiated quickly -- that is, no parts of
it were missed.

The researchers compared the new technique to conventional CT scanning
methods, where a sample rotates as a full beam is directed on to it,
finding it delivered the same quality of image at a vastly reduced dose.

Dr Charlotte Hagen (UCL Medical Physics & Biomedical Engineering),
first author of the paper and a member of the UCL Advanced X-Ray Imaging
Group, said: "Being able to reduce the dose of a CT scan is a long-sought
goal. Our technique opens new possibilities for medical research and we
believe that it can be adjusted for use in medical scanners, helping
to reduce a key source of radiation for people in many countries."
In the NHS, about five million CT scans are performed every year;
in the United States, the annual number of CT scans is more than 80
million. CT scanning is thought to account for a quarter of Americans'
total exposure to radiation.

Conventional CT scans involve an X-ray beam being rotated around the
patient.

The new "cycloidal" method combines this rotation with a simultaneous
backwards and forwards motion.

The use of beamlets enables a sharper image resolution, as the part of
the scanner "reading" the information from the X-ray is able to locate
where the information is coming from more precisely.

Professor Sandro Olivo (UCL Medical Physics & Biomedical Engineering),
senior author of the paper, said: "This new method fixes two problems. It
can be used to reduce the dose, but if deployed at the same dose it can increase the resolution of the image.

"This means that the sharpness of the image can be easily adjusted using
masks with different-sized apertures, allowing greater flexibility and
freeing the resolution from the constraints of the scanner's hardware."

========================================================================== Story Source: Materials provided by University_College_London. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Charlotte K. Hagen, Fabio A. Vittoria, Oriol Roche i Morgo', Marco
Endrizzi, Alessandro Olivo. Cycloidal Computed Tomography. Physical
Review Applied, 2020; 14 (1) DOI: 10.1103/PhysRevApplied.14.014069 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200723115909.htm

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