New heart scanning technique to reduce radiation risk for patients
A new technique promises to reduce the radiation risk for
patients and staff, a study recently published in the Journal of
Nuclear Cardiology shows.
Researchers who led the study at the Nuclear Medicine Department
at Central Manchester University Hospitals believe that these
findings will offer a more efficient and sustainable approach to
delivering myocardial perfusion imaging. The department
provides scanning for patients with heart conditions across the
North West region and performed approximately 2300 scans in
Coronary artery disease (CAD) is the UK's largest killer and
those living in the North West are more likely to die from the
condition than anywhere else in England2. In
patients with CAD, the arteries that supply the heart muscle with
oxygen-rich blood become narrowed by a gradual build-up of fatty
deposits. Eventually this may block the delivery of oxygen to
the heart causing permanent damage to the heart, known as a heart
attack. A myocardial perfusion scan is a non-invasive scan
that gives doctors information about the blood supply to the heart
muscle. It is one of the tests that have an important role in the
management of patients with CAD, with thousands of scans performed
across the UK every year.
A myocardial perfusion scan uses a short-lived radioactive
tracer that is injected into a vein in a patient's arm and
accumulates in the heart muscle. The radioactive tracer emits
gamma rays and the position of these is detected using a gamma
camera. The gamma camera has a lead filter (collimator)
attached to the front of the camera to control the amount of
radioactivity it detects.
In the published study, a perspex model filled with water was
used to mimic the distribution of radioactive tracer from a patient
heart scan. This approach allows researchers to evaluate
alternative techniques without unnecessary radiation risk for
The researchers compared the quality of images using alternative
collimators, that allow more radioactivity through to the camera,
against standard collimators. The benefit of the alternative
collimators is that less radioactive tracer can be used and the
images can be acquired in less time. However the images
produced have less fine detail.
In this study, the researchers found that by using an advanced
image processing technique called "resolution recovery" they were
able to create images using the alternative collimator, which were
of similar or better quality than the standard procedure.
This new approach reduces the amount of radioactive tracer required
and will lead to a reduction of patient radiation dose by
Ian Armstrong, Principal Physicist in Nuclear Medicine, said
"We undertake considerable research into optimising nuclear
medicine techniques for the benefit of our patients and to also
help our staff work more efficiently. As physicists, we have
a responsibility to drive efficiencies in the way our departments
work. As well as reducing the radiation risk, we hope that
this new approach will enable us to provide the same high-quality
scans using less radioactive tracer.
"The next step is to undertake a clinical trial to compare the
effectiveness of the new procedure against standard practice in
patients. We hope to start recruiting patients to participate
in this trial in spring 2016."