Toshiba Medical
Systems Safety in
Ultrasound and
Image manipulation
Erica Oliver Clinical
Product Specialist Ultrasound
BMUS STATEMENT
Diagnostic ultrasound is an imaging modality that is useful in a
wide range of clinical applications, and in particular, prenatal
diagnosis. There is, to date, no evidence that
diagnostic ultrasound has produced any harm to humans
(including the developing fetus).
BMUS GUIDLINES
Despite its apparent excellent safety record, ultrasound imaging
involves the deposition of energy in the body, and should only be
used for medical diagnosis, with the equipment only
being used by people who are fully trained in its safe and proper
operation.
It is the scan operator who is responsible for controlling the
output of the ultrasound equipment. This requires a good
knowledge of scanner settings, and an understanding of their
effect on potential thermal and mechanical bio-effects.
BMUS Recommended Range and
Scanning Times
BMUS GUIDELINES INDICIES
1.The thermal index for soft tissue (TIS)
This is used when ultrasound only insonates soft tissue, as, for
example, during obstetric scanning up to 10 weeks after last
menstrual period(LMP).
2. The thermal index for bone (TIB)
This is used when the ultrasound beam impinges on bone at or
near its focal region, as, for example, in any fetal scan more
than 10 weeks after LMP.
3. The thermal index for cranial bone (TIC)
This is used when the ultrasound transducer is very close to
bone, as, for example, during trans-cranial scanning of the
neonatal skull.
Thermal Hazards
• A temp elevation of 1.5ºC will cause no harm to tissue
• A temp elevation of 4ºC maintained for 5 mins or more is
considered harmful to fetal tissue
• Some Doppler & Colour modes may reach this level
• Other modes this is unlikely in current clinical use
Indicated by Thermal Indices (TI) on equipment
Non-thermal hazard
• Can happen where there are gas pockets i.e. lung & intestine
particularly in neonates
• Indicated by mechanical index (MI) value of 0.4 or more
• Possibility of damage in small localised areas cannot be
excluded
• MI displayed on equipment on the monitor
ALARA
The ALARA principle (i.e. as low as reasonably achievable).
If however the patient has a larger body habitus it is reasonable
to use higher output or longer examination times than in others:
for example, the risks of missing a fetal anomaly must be
weighed against the risk of harm from potential bioeffects.
When overall times longer than those recommended here are
essential, the probe should be removed from the patient
whenever possible, to minimise exposure.
Consequently, it is essential for operators of ultrasound
scanners should be properly trained and fully informed when
making decisions of this nature.
WFUMB/ISUOG Statement on the Safe Use of Doppler
Ultrasound During 11-14 week scans (or earlier in pregnancy)
‘Pulsed Doppler (spectral, power and colour flow imaging)
ultrasound should not be used routinely’
Approved by WFUMB Administrative Council, January 27, 2011.
This text is identical to that in the statement published by AFSUMB, AIUM, BMUS,
EFSUMB and JSUMB
System Optimisation
Do you know where your acoustic knob is?
Do you know what the acoustic power is set at?
Do you know where your Mechanical and thermal Indices can be
found?
Do you know what the indices do when you put harmonics on?
Do you know what the indices do when you put colour Doppler
on and Spectral Doppler?
MECHANICAL INDEX
Mechanical Index found on left hand side of monitor whilst scanning is live
Thermal Indicies
Thermal Index top right hand side of monitor
Acoustic Knob
Located under the TGC
Power Outputs with colour and spectral
Doppler
3.9 TIB
Knobology
Manipulation of the system for optimum image quality
Frequency
The transducers are multi frequency for example 6 Mhz to 1 Mhz the lower
the frequency the better the penetration the higher the frequency the
better the resolution
Aplipure (compounding)
Aplipure or compounding allows electronic beam steering multiple angles
improves continuity of structures and boundaries. Allows better signal to
noise ratio contrast resolution whilst maintaining penetration.
Precision Imaging
An electronic edge enhancement separating structures from clutter or
noise.
Focus
The focus can be altered via both these buttons. Focus electronically
narrow the beam for better resolution and should be placed just on or just
behind the area of interest
Gain and TGC (time gain compensation)
The overall gain amplifies echos across the whole image whereas the TGC
amplifies the allocated echos at a given depth selected by the operator
Depth and Zoom
The depth button when pressed becomes your zoom or magnification the
zoom can be selected to be either a pan zoom or a centre zoom the new
Aplio series has high definition zoom features to give superior resolution .
HDD and storage 180 GB
The system is capable of storing up to 180 GB of both still images and clips
onto the hard drive. This can be transferred to a CD, USB PACs, external
database, and black and white print all patient identification can be
removed for this purpose if needed.
References
ter Haar G, Duck FA (eds). 2000. The Safe Use of
Ultrasound in Medical Diagnosis, BMUS/BIR, London.
BMUS. 2010. Guidelines for the safe use of diagnostic
ultrasound equipment. Ultrasound, 18 52-59.
WFUMB. 1998. World Federation for Ultrasound in
Medicine and Biology Symposium on Safety if
Ultrasound in Medicine: conclusions and
recommendations on thermal and non-thermal
mechanisms for biological effects of ultrasound, Barnett
SB (editor) Ultrasound Med. Biol, 24, 1-55
Thank you for listening