Download Somatom Definition Flash computed tomography scanner

NEWS BRIEF
Somatom Definition Flash
computed tomography scanner
for cardiac and other imaging
March 2010
The Somatom Definition Flash produced by Siemens
Healthcare is a type of computed tomography (CT)
scanner comprising of a pair of sources and detectors
that move around the patient in complementary spirals.
It captures information more rapidly and with lower
radiation exposure than a conventional single source/
detector computed tomography scanner. The Somatom
Definition Flash Scanner can be used to undertake
imaging in those who cannot lie still for prolonged
periods or who find it difficult to hold their breath. It
also provides rapid and relatively low dose coronary
artery imaging, cardiac stress perfusion scans and whole
brain perfusion imaging.
© Siemens Healthcare
Background
In conventional computed tomography a single X-ray source and detector move
slowly down and around the patient to obtain overlapping images that are joined
together and used in the diagnosis of a wide range of medical conditions.
In 2009-10, 3.7 million computed tomography scans were performed in the National
Health Service1.
Current Practice
This news brief is
based on
information
available at the
time of research
and a limited
literature search.
It is not intended
to be a definitive
statement on the
safety, efficacy or
effectiveness of
the health
technology
covered and
should not be
used for
commercial
purposes or
commissioning
without additional
information.
For a person to have a successful conventional computed tomography scan they may
have to lie still for around 20 minutes and patients, such as children, who find this
difficult may have to be sedated. Where moving structures such as the heart or chest
are being scanned, patients will need to be able to reliably hold their breath for a
short while. This can be difficult for some people, and drugs may have to given to
slow down the heart.
New Technology
In contrast to the conventional single source computed tomography scanners the
Somatom Definition Flash computed tomography scanner consists of a pair of X-ray
sources and detectors. These are rotated around the patient in complementary spirals and the overlapping images overlaid to produce the final x-ray image of the patient. The company states that the scanner can produce an image more rapidly than
conventional computed tomography techniques (4 seconds for a full body scan, under 1 second for a chest scan) and high quality images can be obtained with around
half the radiation dose of conventional computed tomography2.
By rapidly producing high quality scans with a significantly reduced radiation exposure, Siemens Healthcare believe that their Somatom Definition Flash scanner will
extend the role of computed tomography to patient groups who are unsuitable for
conventional computed tomography. With a rapid scan time those who find lying still
difficult may be able to be scanned without sedation, drugs to slow the heart would
be less likely to be needed and breath holding would no longer be mandatory 3.
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With its rapid action Siemens Healthcare believe that their Somatom Definition Flash
scanner could take the place of other more invasive diagnostic techniques such as
coronary catheterisation and single photon emission computed tomography (SPECT),
cardiac stress perfusion tests, whole brain perfusion imaging and full body scanning
for trauma patients.
The Somatom Definition Flash scanner was CE marked in December 2009. As of the
first quarter of 2010 there were five scanners in clinical use in the United Kingdom
with a further 6 installations planned.
Clinical Studies and Research Questions
The first clinical data for the Somatom Definition Flash scanner were presented at the
European Congress of Radiology in March 20094. Several small studies of technical
performance in chest and heart imaging have been conducted and are also ongoing.
A study of 31 patients with acute chest pain compared the results from (a) a
Somatom Definition Flash scanner scan, (b) a standard non-gated chest scan, and (c)
a conventional retrospectively ECG gated ‘triple rule-out’ protocol. Reported radiation
doses were (a) 4.08±0.81 milliSevert, (b)20.4±5.3 milliSeverts and (c) 4.40±0.83
milliSeverts respectively. Scan times were 0.7 seconds (±0.1) for the Somatom
Definition Flash, and 15 seconds (±3) for conventional chest scans. The authors
concluded that the Somatom Definition Flash scanner requires about one-fifth of the
radiation dose of conventional ECG gated triple-rule-out protocols, matching that of a
standard non-gated chest scan, but with a much shorter scan time (less than 1
second)5.
In a conference abstract, a Somatom Definition Flash scanner was reported to
produce a scan of the whole heart in around a quarter of a second with a radiation
dose of approximately 0.95 milliSieverts6.
A study evaluating radiation dosing performance reported that a Somatom Definition
Flash scanner performed a stress perfusion test with a radiation exposure of less
than 10 milliSieverts7.
Potential Impact
By performing more rapid scanning the Somatom Definition Flash scanner may
reduce the need for drugs for sedation or slowing down the heart. As well as the
potential health benefits to the individual patients this might also reduce the total
time needed for scanning and recovery in hospital.
The Somatom Definition Flash scanner may offer a less invasive alternative to cardiac
catheterisation for diagnosing coronary artery disease which may be more acceptable
to patients. It is also of benefit to the patient if radiation dosage during scanning can
be reduced.
Faster scanning times, as claimed by the company, may improve the experience for
the patients and may increase the total number of scans that can be undertaken over
a period of time.
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References
1.
Department of Health Publication Statistics Imaging and Radiodiagnostic Activity, 2009/10. http://
www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsStatistics/DH_117795
Accessed 3 December 2010.
2.
Carrington C. SOMATOM Definition Flash: impressive performance. Somatom Sessions 6, May 2009.
3.
Company correspondence, 21st May 2009.
4.
Becker CR. SOMATOM Definition AS: one CT for all clinical needs. European Congress of Radiology.
March 2009. Satellite Symposium SY17, presentation number E-50.
5.
Sommer WH, Schenzle MD, Becker JC et al. Saving dose in triple-rule-out computed tomography
examination using a high-pitch dual spiral technique. Investigative Radiology 2010;45(2):64-71.
6.
Achenbach S, Marwan M, Ropers D et al. Sub-mSv coronary CT angiography using prospectively
ECG-triggered high-pitch spiral acquisition. Fourth annual scientific meeting of the Society for
Cardiovascular Computed Tomography (SCCT). July 2009. Abstract number 04.
7.
Bamberg F, Nikolaou K, Becker A et al. Myocardial stress perfusion with a novel dual-source CT
scanner - technical update and initial clinical experience. Imaging Decisions MRI 2009;13(2):49-51
(3).
The National Institute for Health Research (NIHR) National Horizon Scanning Centre Research Programme is funded by the
Department of Health. The views expressed in this publication are not necessarily those of the National Health Service, the
NIHR or the Department of Health.
The National Horizon Scanning Centre,
University of Birmingham, United Kingdom
[email protected]
www.haps.bham.ac.uk/publichealth/horizon
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