Giáo trình Tiếng Anh chuyên ngành Y - Phần 2

Giáo trình Tiếng Anh chuyên ngành Y - Phần 2

Unit 1: The defibrillator

In the United States, hundreds of thousands of person die of sudden cardiacarrest each year If they could be treated with a defibrillator within one minute of attack, 80% would have an increased chance of survival However If this treatment

is delayed by only ten minutes, the statistic fall from 80% to 15%, thus illustrating how important the defibrillator is, and how important it is to have it available to the general population

A defibrillator is an electronic device that creates a sustained myocardial depolarization of a patient’s heart in order to stop ventricular fibrillation or atrial fibrillation These fibrillations occur because ectopic, or out-of-place, stimulus sites take place in the heart and cause a disorganized cardiac muscle contraction

When this defibrillation happens to the ventricles, it causes a drastically reduced cardiac output of blood flow and result in death in a few minutes An atrial fibrillation causes reduced cardiac output but is usually not fatal The D.C defibrillators must have a mechanism for adjusting the energy level, by controlling either the amplitude or the duration of the defibrillator pulse A schematic of the D.C defibrillator like that introduced by Bernard Lown in 1962 is given in Figure

1 When the switch is in the charge position, current flows through the diode in one direction and charges the capacitor to its peak value, Vp The voltage Vp can

be varied by changing the setting on the varactor The energy stored in the capacitor and available for defibrillations, Wa, is Wa = ½.CV2p.

Therefore the energy available from the defibrillator is varied by the varactor setting

The defibrillator pulse is delivered by placing paddles covered with an electrode electrolyte gel against the skin of the patient and placing the switch in the discharge position The paddles have a metal surface from 8 to 10 cm in diameter for adult patients They may be placed either in the anterior – anterior position so that the current flows from the back to the chest through the heat In the anterior – anterior position, one paddle is placed above the apex of the heart and the other is placed on the sternum This causes the current to flow from the bottom to the top of the heart

TASK 1

Read the text and answer these questions about the text.

1 How many people die of sudden cardiac arrest each year?

2 Why is it important to have the defibrillator available to the general population?

(tại sao việc có máy khử rung tim có thể dùng rộng rãi trong dân chúng là

4 What does the energy required depend on?

5 What happens when the switch is in the charge position?

6 How the defibrillator pulse is is delivered?

7 How large is a metal surface?

8 Do you think defibrillator is indeed a hazardous procedure?

TASK 2

Using the line references given, look back in the text and find the reference for the words in italics.

1 They could be treated.

2 That creates a sustained myocardial depolarization

3 It causes a drastically reduced ….

4 They may be placed…

5 This causes the current …

TASK 3

Fill in the blanks from the words given sometimes more than one way apply (change if necessary).

pediatric for example defibrillator stop

therefore available use reduce

This discharge switch is usually mounted on the paddle It is important that the attendants using the defibrillator avoid having the pulse pass through their own bodies electrode gel on the paddle handle could provide a path for the defibrillation pulse through on arm of the attendant and through the heart to the other arm An attendant touching the patient is likewise in danger of a shock

Because of the surface resistance, the defibrillator pulse may be delivered to the open heart using paddles from 4 to 5 cm in diameter, and the voltage levels may be reduced by one third For patients, the external paddles are approximately 5 cm in diameter and energy levels of about 50 J are delivered

Defibrillation is indeed a hazardous procedure, since it involves

the heart, and if applied incorrectly, it could induce fibrillation in a normal heart it is essential that a diagnosis be made by trained specialists to ensure that the patient needs the treatment before it is initiated In order to reduce this risk, and to make the defibrillator For more cardiac arrest victims more quickly, diagnostic circuitry is used to assess that a fibrillation is in fact occurring before the defibrillation pulse is applied to a patient This then makes it safe for attendants with less training to the defibrillator

LANGUAGE FOCUS

Cause and result

It is very important to understand the different ways of expressing the relationship between the causes and the results of an action when we are reading English This cause-result relationship is commonly used in scientific writing In the next two parts we will learn how to use causes and results

Group A(The cause and result must be in sentence form)

Subordinators: because, since, if

We delayed our departure on account of the bad weather.

Due to the heavy traffic, he was late.

Exercise 1: Read the following sentences and underline that part which expresses

the cause and the result.

1 Because of the high internal impedance of the brain wave source, the input impedance of the differential amplifies should exceed 10 MΩ to prevent loss of signal amplitude

2 Since the x-ray tube is operated in its thermally limited mode, the x-ray intensity in watts per square meter is adjusted by the x-ray tube filament current

3 Robots are better at this task, not because they are faster or cheaper than humans, but because they work in a place where humans cannot

4 When robots malfunction, it is usually due to mistakes in the programming

or the design

 Air pollution

 Deterioration of substances

1 a Many people do not explore new software

b They are comfortable with what they already have (because)

2 a The increase in efficiency of diff amp

b A reduction in the cost of diff amp, from $ 350 to about 35 cents (lead to)

3 a Cardio version is used in circumstances where the heart is still pumping

b Some kill is required to prevent the defibrillating pulse from causing fibrillation due to incorrect timing (since)

4 a Deterioration of the Reagent Strip test areas

b Exposure to light, ambient moisture or heat (due to)

Unit 2: Medical X-Ray equipment

TASK 1

Choose one correct word or phrase given below to complete each of the following sentences.

impulse diagnosis properly functional electron beam

1 His willingness to act on and be diverted from the task at hand drove him to investigate further

2 An X-ray is produced by an when one of the electrons collides with an atom in the anode

3 X-rays were being used in medical

4 X-rays can be dangerous when not used and may cause cancer

5 A diagram of an X-ray tube shows a filament – heated cathode,

an anode, and a glass vacuum enclosure

The discovery of X-Ray by Roentgen in 1895 was a total surprise to him and everyone else at the time He was not searching for the way to see into the body without surgery Rather, he was investigating the cathode rays of a vacuum tube diode when he noticed changes being caused in photographic material, not directly involved with his experiments His curiosity and his willingness to act on impulse and be diverted from the task at hand drove him to investigate further.Within a period of only days he subsequently discovered that x-rays:

- Cause barium platinocyanide to exhibit fluorescence

- Affect photographic emulsions

- Discharge electrified objects

- Make certain materials transparent

- Can be collimates into pinholes

- Are created by high – energy cathode ray tube

- Are more efficiently produced by heavy elements

Within two weeks of their discovery, x – rays were being used in medical diagnosis, and they have been indispensable ever since When we consider that it took two centuries to develop the internal combustion engine, the lightning speed with which such a revolutionary technique as x – ray diagnosis appeared is nothing less than amazing

What Roentgen did not discover, however, and that it took scientists about 50 years to fully appreciate is that x-rays can be dangerous when not properly used, and may cause cancer

Over the years x-ray equipment has been continually improved major engineering objectives have been to.

- Improve the quality of the image

- Heighten the contrast between different tissues

- Improve size resolution

- Minimize the dose of x-rays used on the patient

The X – Ray tube

The x-ray tube is simply a glass – enclosed vacuum tube diode consisting

of a cathode that thermally emits electrons and an anode that attracts these electrons A functional diagram of an x-ray tube is given in Figure 1, which shows

a filament source voltage VF causes a current If to flow through the filament coil,heating the cathode metal Electrons in the cathode are boiled off the metal into the vacuum In an x-ray the anode voltage VA is high enough that these electrons are swept across to the anode and form the beam current, IB VA on the tube is very high, on the order of 100 KV This high voltage impels the electron to a very high velocity Approximately 1% of the electrons upon entering the anode collide with atoms and produce x-rays The x-rays then pass through the tube into space

2 X-rays are created by a high-fuel cathode-ray tube

3 Major engineering objects only have been to improve the quality of the image and size resolution

4 About 1% of the electrons upon entering the anode collide with atoms and produce x-rays

5 An x-ray is produced by an electron beam when one of the electrons strikes

an atom in the anode

6 Bremsstrahlung radiation comprises most of the x-ray energy

TASK 3

Choose the given word to complete each sentence You may have to change some words slightly.

1 Scattered, scattering, scatter

a A second type of collision, ……… of the incident electron produces a spectrum of x-ray radiation

b To absorb the ……… x-rays and eliminate the subsequent blurring, which is tapered to pass the x-rays incident on the patient.

c X-rays inside the patient create x-ray ……… which tends to blur the images

2 Produce, producing, product

a X-rays ……… by the tube anode are either absorbed in lead or collimated through the x-ray tube opening

b The energy absorbed by the anode is proportional to the ………

of the anode voltage

c The x-rays strike a fluorescent screen, ……… light

3 Ionization, ionize, ionizing

a The detectors may consist of ……… chambers filled with a gas such as xenon, sealed at both ends, and having two conductors, forming a capacitor on the sides

b An x-ray entering the chamber ……… a xenon atom, causing it

to migrate to the capacitor plate, and causing a current in the high-voltage lead

c As voltage V is increased, the ……… have secondary collisions and produce more ………

4 Amplify, amplified, amplifier.

a A set of plates ……… the electron beams by a process of secondary emission

b The output current through R2 is thus ……… and may be detected with a differential amplifier

5 Localize, location, locate

a The numbers in the matrix correspond to the attenuation of

……… on a tissue slice

b These medicines are typically absorbed by the organ and emit radiation that can be detected and ………

c Instrumentation and components that detect, measure, and

……… radioactive medicines are described

Unit 3: The microprocessor – based equipment

The vast increase in the use of medical equipment was driven by the invention of the transistor in 1948, and by the subsequent development of solid-state electronics, which made possible the small dedicated computer The importance of the computer in medical equipment increased rapidly in the 1970s,

in particular with the invention of the computer tomography (CT) scanner, an instrument that would be virtually impossible without dedicated computers Many types of medical equipment are improved by the incorporation of dedicated computers, even though, in principle, they worked fine without them This is not the case with ST scanners and magnetic resonance images (MRI) For them the dedicated computer has always been an essential element

The microprocessor, or computer on a chip, is the component that makes inexpensive dedicated computers possible By 1970 manufactures could fabricate

a thousand transistors on a chip about one square inch in size This made possible dedicated computers such as the ordinary pocket calculator At present, a million gates can be fabricated on a chip, which means that relatively powerful computers can be made quite small These chips are so inexpensive that a computer once costing one or two thousand dollars is now available for about ten dollars Because

of this, they are now widely used in calculators, watches, automobiles, and many types of medical equipment

Microprocessors are used, for example, to do signal processing on an EGG waveform Holter ECG waveform storage devices are now available to monitorheart patients and to store selected arrhythmia events for later analysis They are used to save nurse’s time in central station monitoring In pulmonary instrumentation they compute such variables as vital capacity, forced expiratory flow, and peak flow rates They are used in anesthesia machines to monitor gas flow and blood gas parameters They are used in electroencephalography to monitor frequency and the power spectrum

Because microprocessors are so widely used, the engineer and technician working with hospital equipment clearly need to be familiar with them

TASK 1

Complete the sentences below using the appropriate words in the box.

Even though Medical Chips For example Magnetic

In the use Worked Improved Inexpensive Gates Dedicated

1 The vast increase ……… of medical equipment was driven by the invention of the transistor in 1948

2 The importance of the computer in ……… equipment increased rapidly in the 1970s.

3 Many types of medical equipment are ……… by the incorporation of ……… computers

4 At present, a million ……… can be fabricated on a chip

5 Microprocessors are used, ………, to do signal processing on an ECG waveform

TASK 2

Read the text and decide whether the following statements are true (T) or false (F) in relation to the information in the text.

1 In particular with the invention of the computer tomography (CT) scanner,

an instrument that would be virtually impracticable without dedicated computers

2 The dedicated computer has always been an irreplaceable element for magnetic resonance images

3 By 1970 manufactures could fabricate a thousand transistors on a chop about one square inch in size

4 At present, a million gates can be fabricated on a chip, which means that comparatively powerful computer once costing one or two thousand dollars

is now ready for about 10 dollars

5 Microprocessors are only used to do signal processing on an ECG waveform

TASK 3

Look back in the text and find the reference for the words in italics.

1 An instrument that would be virtually…

2 They work fine without them ….

3 For them the dedicated computer …

4 This made possible dedicated computer …

5 These chips are so inexpensive …

6 ……… which means that relatively powerful …

7 Because of this, they are now available …

8 They are used in anesthesia machines to …

Unit 4: Ultrasonic equipment

Ultrasonic equipment serves a variety of functions in medicine It is used for imaging internal organ non-invasively It is used to apply massage and deep –heat therapy to muscle tissue And it is used to measure blood flow and blood pressure non-invasively

The principle of imaging, or making pictures of internal organs, is that of ultrasonic wave reflection Ultrasonic waves reflect from the boundaries of two tissues, just as waves reflect from an object in water Because the amount of reflection differs in different tissues, it is possible to distinguish between materials and make images of them using ultrasonic

The quality making ultrasonic waves therapeutic is that they cause tissue matter to vibrate and heat up It is the heat that has therapeutic effects For use as therapy, it is necessary to couple relatively high power (up to approximately 5 W/cm2) into the tissue

Blood pressure and blood low is measured by application of the Doppler effect This effect is the increase in frequency of a sound reflected by a body approaching the source of the sound To observe this effect, sing a steady tone then move your hand rapidly toward your mouth You will hear the increase in the pitch due to the motion of your hand

Ultrasonic Imaging Equipment

Ultrasonic voltage generator in Ultrasonic Imaging devices hits the piezoelectric transducer with a short pulse and causes it to oscillate at its resonant frequency It is also possible to use a pulse – modulated generator to drive the piezoelectric crystal The pulse generated would be long compared to the period of the 1 to 10 MHz ultrasonic oscillation It would be short, however, compared to the acoustic transmission time in the tissue Sound velocity in the body averages about 1540 m/s therefore, 1mm in distance requires 0.65 Microsecond on the average

The pulse of ultrasonic energy travels into the tissue It is reflected from tissue boundaries, causing echoes By the time the echoes reach the transducer, the pulse generator has turned off, and the echo creates an oscillation in the transducer again The echo is like that of a drum beat reverberating off a wall, except the drum operates at a lower, audible frequency

TASK 2 word association

One word connects each set of four below All the words have medical connections What are they?

transplant failure

disease rate

involuntary relaxant

replacement sex

labour throbbing

pressure

donor sugar