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Файл:English Guide for Bio-Medical Engineers. Учебное пособие
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- However, devices with risk include antitheft systems in shops and other business
premises and metal detectors. They are unlikely to cause clinically significant symptoms
in most patients but patients should not stay nearby for longer than is necessary.
- Any hand-held metal detector should not be held near the pacemaker for any
longer than is necessary.
- Household devices such as shavers, hairdryers and microwave ovens are not a
problem, as long as they are well maintained.
- Household tools such as drills, mowers and electric screwdrivers can be used
normally.
- A mobile phone or a cordless phone can be used safely, but the phone should be
kept more than 6 inches away from the pacemaker. The ear on the opposite side to the
pacemaker should always be used, and the phone should not be put in a pocket over the
pacemaker.
Travelling and security systems
- Airport screening systems and antitheft systems in shops and libraries may (rarely)
cause problems and there is also a small chance that the pacemaker may trigger the alarms.
- The pacemaker registration card should always be carried by the patient.
- If a patient with a pacemaker has to go through a security gateway, they should go
through quickly and not stand close to the gateway for too long.
At work
- Some workplaces have strong electromagnetic fields which can interfere with the
pacemaker - eg, arc welding.
- Power-generating equipment, arc welding equipment and powerful magnets (as in
medical devices, heavy equipment or motors) can inhibit pulse generators and there is a
risk that the pacemaker may not work properly for patients who work closely with or near
such equipment.
5.3.2 Match the words and word-combinations in the right hand column with the
words and word-combinations in the left hand column:
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driving licence
dizziness or fainting
check-up
passenger-carrying vehicle
strenuous
collision
protective pad
unpredictable
short-wave or microwave diathermy
transcutaneous
antitheft systems
household devices
arc welding equipment
power-generating equipment
пассажирский автомобиль
коротковолновая и микроволновая
диатермия
столкновение
водительские права
непредсказуемый
проверка
защитная накладка
транскутанный (чреcкожный)
головокружение или обморок
напряженный
энергетическое оборудование
оборудование для дуговой сварки
бытовые приборы
противоугонные системы
5.3.3 Make the list of precautions for patients that have a pacemaker.
5.3.4 Say whether the following statements are True or False and correct the false
ones:
1) The patient must not inform the Driver and Vehicle Licensing Agency that they
have a pacemaker.
2) The patient attends regular check-ups in the ordinary clinic.
3) The patient cannot drive the vehicles for ten weeks after the pacemaker is fitted.
4) The patient can apply for another licence when he/she no longer has any
symptoms that would affect driving - eg, dizziness or fainting.
5) Any strenuous activity should be avoided for about five weeks after the
pacemaker has been fitted.
6) An employer should be informed that the patient has a pacemaker.
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7) Always show the pacemaker registration card to any doctor or dentist providing
1) The current licence is replaced with
a three-year licence and the patient will
have to go ... .
2) Any strenuous activity should be
avoided for about three to four weeks ...
.
3) For contact sports, care should be
taken to avoid collisions that may
1) a protective pad should be considered
2) may interfere with pacemakers
3) to a pacemaker clinic regularly
treatment.
8) Some hospital equipment, including equipment used in surgery doesn't interfere
with pacemakers.
9) The pacemaker should be shielded as much as possible and moved if it lies
directly in the radiation field.
10) MRI scans are not dangerous with a pacemaker and the patient should have an
MRI scan.
11) Most pacemakers are very resistant to outside interference without any special
circuits.
12) Any hand-held metal detector should not be held near the pacemaker for any
longer than is necessary.
13) Household devices such as shavers, hairdryers and microwave ovens are a
problem, even if they are well maintained.
14) Airport screening systems and antitheft systems in shops and libraries often
cause problems and there is also a great chance that the pacemaker may trigger the alarms.
15) The pacemaker registration card should always be carried by the patient.
5.3.5 Read the text again and match the phrases on the left with the phrases on the
right:
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damage the pacemaker, and ... .
4) Most pacemaker generators have X-
ray code... .
5) Some hospital equipment, including
equipment used in surgery, ... .
6) Radiotherapy may damage ... .
7) The degree of damage is
unpredictable and ... .
8) Short-wave or microwave diathermy
may bypass the pacemaker's noise
protection and ... .
9) Any hand-held metal detector
should not be held near the pacemaker
... .
10) Household devices such as shavers,
hairdryers and microwave ovens are not
a problem, ... .
11) A mobile phone or a cordless phone
can be used safely, but the phone should
be kept ... .
12) Some workplaces have strong
electromagnetic fields which ... .
4) the pacemaker's circuits
5) after the pacemaker has been fitted
6) that can be seen on a standard CXR
7) may vary with different systems
8) as long as they are well maintained
9) for any longer than is necessary
10) interfere with or permanently
damage the pulse generator
11) can interfere with the pacemaker
12) more than 6 inches away from the
pacemaker
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6 Unit 6. Other devices with pacemaker function
Text A. 6.1 Other devices with pacemaker function
6.1.1 Read and translate text A:
Sometimes devices resembling pacemakers, called implantable cardioverterdefibrillators (ICDs) are implanted. These devices are often used in the treatment of
patients at risk from sudden cardiac death. An ICD has the ability to treat many types of
heart rhythm disturbances by means of pacing, cardioversion, or defibrillation. Some ICD
devices can distinguish between ventricular fibrillation and ventricular tachycardia (VT),
and may try to pace the heart faster than its intrinsic rate in the case of VT, to try to break
the tachycardia before it progresses to ventricular fibrillation. This is known as fastpacing, overdrive pacing, or anti-tachycardia pacing (ATP). ATP is only effective if the
underlying rhythm is ventricular tachycardia, and is never effective if the rhythm is
ventricular fibrillation.
Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI),
or magnetic resonance tomography (MRT) is a medical imaging technique used
in radiology to visualize internal structures of the body in detail. MRI makes use of the
property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body.
An MRI scanner is a device in which the patient lies within a large,
powerful magnet where the magnetic field is used to align the magnetization of
some atomic nuclei in the body, and radio frequency magnetic fields are applied to
systematically alter the alignment of this magnetization. This causes the nuclei to produce
a rotating magnetic field detectable by the scanner and this information is recorded to
construct an image of the scanned area of the body. Magnetic field gradients cause nuclei
at different locations to process at different speeds, which allows spatial information to be
recovered using Fourier analysis of the measured signal. By using gradients in different
directions 2D images or 3D volumes can be obtained in any arbitrary orientation.
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MRI provides good contrast between the different soft tissues of the body, which
makes it especially useful in imaging the brain, muscles, the heart, and cancers compared
with other medical imaging techniques such as computed tomography (CT) or X-rays.
Unlike CT scans or traditional X-rays, MRI does not use ionizing radiation.
6.1.2 Write the transcription of following words and word-combinations, find out
the meanings:
implantable cardioverter-defibrillators, treatment, ventricular, to pace the heart, fast
intrinsic rate, to visualize internal structures of the body, to image nuclei of atoms inside
the body, to align, rotating magnetic field gradients, to process at different speeds,
muscles, brain, soft tissues.
6.1.3 Translate the derivatives of the following words:
implant – implantable, implanted, implantation;
treat – treatment, treated;
disturb – disturbance;
pace – pacing;
drive – driver, driving, overdrive, underdrive;
image – imaging, imagination;
magnet – magnetic, magnetization;
power – powerful, powerless;
frequent – frequency, frequently;
align – alignment, aligning;
detect – detectable, detection;
scan – scanner, scanned, scanning;
recover – recovery, recovered;
measure – measurement, measured.
6.1.4 Divide the text into logical parts and entitle them.
6.1.5 Make up the plan of the text A and retell it according to the plan.
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Text B. 6.2 How MRI works
6.2.1 Read and translate text B:
MRI machines make use of the fact that body tissue contains lots of water, and
hence protons, which get aligned in a large magnetic field. Each water molecule has
two hydrogen nuclei or protons. When a person is inside the powerful magnetic field of
the scanner, the average magnetic moment of many protons becomes aligned with the
direction of the field. A radio frequency current is briefly turned on, producing a
varying electromagnetic field. This electromagnetic field has just the right frequency,
known as the resonance frequency, to be absorbed and flip the spin of the protons in the
magnetic field. After the electromagnetic field is turned off, the spins of the protons return
to thermodynamic equilibrium and the bulk magnetization becomes re-aligned with the
static magnetic field. During this relaxation, a radio frequency signal (electromagnetic
radiation in the RF range) is generated, which can be measured with receiver coils.
Information about the origin of the signal in 3D space can be learned by applying
additional magnetic fields during the scan. These additional magnetic fields can be used to
only generate detectable signal from specific locations in the body (spatial excitation)
and/or to make magnetization at different spatial locations precess at different frequencies,
which enables k-space encoding of spatial information. The 3D images obtained in MRI
can be rotated along arbitrary orientations and manipulated by the doctor to be better able
to detect tiny changes of structures within the body. These fields, generated by passing
electric currents through gradient coils, make the magnetic field strength vary depending
on the position within the magnet. Because this makes the frequency of the released radio
signal also dependent on its origin in a predictable manner, the distribution of protons in
the body can be mathematically recovered from the signal, typically by the use of the
inverse Fourier transform.
Protons in different tissues return to their equilibrium state at different relaxation
rates. Different tissue variables, including spin density, T1 and T2 relaxation times, and
flow and spectral shifts can be used to construct images. By changing the settings on the
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scanner, this effect is used to create contrast between different types of body tissue or
to make use
to get aligned
average
to flip
spin of the protons
equilibrium
coil
detectable
additional
spatial
location
tiny
distribution
выравнивать
средний
подбрасывать
вращение протонов
равновесие
катушка
определяемый
дополнительный
пространственный
крошечный
распределение
мозг
плотность
between other properties, as in MRI and diffusion MRI.
MRI is used to image every part of the body, and is particularly useful for tissues
with many hydrogen nuclei and little density contrast, such as
the brain, muscle, connective tissue and most tumors.
6.2.2 Write the transcription of following words and word-combinations, find out
the meanings:
hence, average magnetic moment, flip the spin, thermodynamic equilibrium,
bulk, re-aligned, receiver coil, spatial excitation, specific location, precess, arbitrary
orientation, gradient coil, inverse Fourier transform, spectral shift,
tumor.
6.2.3 Match the words and word-combinations in the right hand column with the
words and word-combinations in the left hand column:
48
settings
density
brain
tumor
размещение, местоположение
настройки
новообразование, опухоль
пользоваться, использовать
6.2.4 Ask five types of questions to the underlined sentences in text B.
Text C. 6.3 Magnetic field, contrast agents and implants
6.3.1 Read and translate text C:
MRI scans require a magnetic field with two properties, uniform field density and
strength. The magnetic field cannot vary more than 1/10,000 of 1 % and field strength
ranges (depending on the scanner) from 0.2 to 3 teslas in strength in currently clinically
used scanners, with research scanners investigating higher field strengths such as seven
teslas. The lower field strengths can be achieved with permanent magnets, which are often
used in "open" MRI scanners, for claustrophobic patients. Higher field strengths can be
achieved only with superconducting magnets. An MRI with a 3.0 tesla strength magnet
may be referred to as a "3-T MRI" or "3-tesla MRI"
Since the gradient coils are within the bore of the scanner, there are large forces
between them and the main field coils, producing most of the noise that is heard during
operation. Without efforts to damp this noise, it can approach 130 decibels (dB) with
strong fields.
MRI contrast agents may be injected intravenously to enhance the appearance of
blood vessels, tumors or inflammation. Contrast agents may also be directly injected into a
joint in the case of arthrograms, MRI images of joints. Unlike CT, MRI uses no ionizing
radiation and is generally a very safe procedure. Nonetheless the strong magnetic fields
and radio pulses can affect metal implants, including cochlear implants and cardiac
pacemakers. There are many electronically activated devices that have approval from the
US FDA to permit MRI procedures in patients under highly specific MRI conditions. In
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the case of cochlear implants, the US FDA has approved some implants for MRI
compatibility. In the case of cardiac pacemakers, the results can sometimes be lethal so
patients with such implants are generally not eligible for MRI.
In 2001, a research team at Stanford invented a new technique which came to be
called "Prepolarized MRI" or PMRI. The team demonstrated that the magnets do not have
to be both uniform and strong, rather two magnets can be used together, where one is
strong and the other one is uniform.
The first magnet in a PMRI scanner is strong, but not uniform. This magnet creates
a very strong magnetic field which varies in uniformity by as much as 40%. This is the
"prepolarize" component. A second much weaker (only requiring the electric power
necessary to run two hairdryers) but far more precise magnet then creates a homogeneous
magnetic field. These two magnets can be ordinary copper wound magnets, which greatly
lowers the cost of an MRI scanner. Because the magnetic field is "tuned" by the second
magnet, a PMRI scan can be obtained immediately adjacent to a metal prosthetic, unlike
an MRI scan.
6.3.2 Match the words and word-combinations under the letter a with the words and
word-combinations under the letter b:
a) gradient coil, to damp this noise, blood vessels, inflammation, cochlear implant,
compatibility, lethal, copper wound magnets, metal prosthetic, adjacent;
b) убирать шумы, градиентная катушка, совместимость, воспаление, кохлеарный
имплантат, кровеносные сосуды, медный катушечный магнит, металлический
протез, летальный, смежный.
6.3.3 Say whether the following statements are True or False and correct the false
ones:
1) MRI scans don't require a magnetic field with two properties, uniform field
density and strength.
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