Medical Technology

Introduction

We could not imagine medical science without modern treatment methods and highly developed technological procedures.

High-tech developments such as ultrasound equipment or magnetic resonance imaging make it easier for doctors to make a diagnosis and save patients having to undergo stressful and risky examinations.

Where would we be without the ability to use X-rays in making a diagnosis, or the use of lasers to ensure the precision of surgical techniques and treatments?  Technological advances in medical care are simply incredible.

   X-rays

Few discoveries have influenced medicine, technology and science as much as X-rays. On 8th November 1895, the German physicist Wilhelm Conrad Röntgen accidentally discovered them when experimenting with cathode rays. He first called them X-rays because of their unknown physical properties. But then he made a sensational discovery: the rays are electromagnetic, like light or radio waves. They can also be reflected or broken. They differ from light rays, however, in that they are very high-energy, making them able to penetrate solid material.

In November 1895, Röntgen presented the first X-ray photographs at a lecture on X-rays: they showed the bones of a hand – and caused a sensation worldwide. The excitement was so great that X-ray equipment was, for instance, set up in shoe shops so that customers could examine their feet through their new footwear.

The harmful effect of X-rays was not recognised until long after their discovery. A lot of people died from the radiation or became ill with leukaemia. Gradually, people began protecting themselves from the rays.

X-rays can be generated by causing currents of electrons to collide under special conditions. A negatively charged hot cathode emits electrons into an evacuated tube. They are accelerated in an electric field and collide into the positively charged anode. This creates the X-rays which can be seen on photographic material or a fluorescent screen.

An X-ray tube and a luminescent screen are the two most important components in X-ray diagnostic equipment. The object under examination is placed between the source of the rays and the screen. The denser the material, the more radiation is absorbed. The image of the object which appears on the screen (a bone for instance) is light. The exact opposite occurs with more penetrable materials such as skin or muscles.

X-ray diagnosis can help to detect fractures, bone cancer or osteoporosis, an illness which breaks down bone tissue.

Ultrasound 

Ultrasound waves are generated by crystals oscillating rapidly in an alternating electrical field and have a frequency range of over 20 kilohertz – higher than the human ear can detect.

During a medical ultrasound examination, also termed sonography, a so-called transducer emits the sound waves as well as receiving the sound which is reflected back. A gel allows the high-frequency ultrasound waves to enter the body more easily. Once inside the body they hit different kinds of tissue: air, bones and other mineralised tissues absorb ultrasound almost completely. Consequently, this diagnostic procedure is not suitable for examining the skeleton or the lungs.

Finally, the ultrasound waves return, similar to an echo, and provide three important pieces of information: how long did they travel? How much energy did they consume? From which direction did they come? The computer uses this data, which is provided by a pattern of sound reflection, to generate a two-dimensional image in a matter of seconds.

New ultrasound equipment can even provide three-dimensional images. These 3D pictures, upon which the finest of structures can be discerned, are especially helpful for the exact medical observation of unborn babies in the womb. Ultrasound is not only used for diagnosis, however, but can also be employed for treatment. The sound waves make it possible to carry out very precise operations without destroying too much tissue. In addition, patients undergoing ultrasound treatment are spared painful wounds and scar formation.

The transducer is the most essential part of ultrasound treatment equipment. It can, for instance, destroy a tumour by bundling sound waves at a point which is calculated exactly beforehand. The temperature at this point rises to up to 90 degrees – and with every “shot” several millimetres of the malignant tissue are burnt.Patients with kidney stones are also frequently treated with ultrasound. The shock waves shatter the stone whilst the procedure itself is very gentle on the patient

magnetic Resonance Imaging

With the help of magnetic resonance imaging or nuclear spin resonance tomography, thin, layered images, so-called tomograms, can be generated of any part of the body from any angle without penetrating the body.

The largely stress-free diagnostic procedure which has been applied since the beginning of the 1980s works with strong magnetic fields and short radio impulses. It is based on so-called nuclear spin. This term describes the property of an atomic nucleus to turn on its own axis like a spinning top, changing it into a tiny magnet. The atomic nuclei of hydrogen, which are present in the body in large numbers, behave in exactly the same way.

In magnetic resonance imaging, the body is subjected to a magnetic field, which is approximately 30,000 times stronger than that of the earth. This artificial magnetic field causes the hydrogen atoms in the body to align themselves in one direction rather like compass needles in a magnetic field on earth.

Radio frequency coils send a short impulse with an exactly determined wave length and strength into the body. The pulse causes the aligned hydrogen atoms to spin. Once the impulse has ceased the atoms quickly return to their original positions. During this so-called relaxation time the hydrogen atoms emit resonance signals which are measured.

The signals received serve as the foundation for generating images of the inside of the body with the aid of computer processes such as those already developed for radiography and computer tomography. The various tissues appear on the screen in different levels of brightness. Tissues which are rich in water are very bright, tissues with a low water content are dark. Accordingly, bones can hardly be seen whilst tissues such as muscles, ligaments, tendons and organs can be recognised clearly in finely graduated tones of grey.

Laser

The term laser is formed from the initials of the words that describe the specific technology involved: Light Amplification by Stimulated Emission of Radiation. To put it simply, a laser – which generates intensive, highly concentrated beams of light – is a light amplifier.

Its history began in New York in 1960. On 7th July of that year, Theodore H. Maiman demonstrated a lamp which emitted a brilliant red line – a concentrated beam of light. And this is how the world’s first laser, which Maiman had constructed using the precious stone ruby, worked: a flash lamp was shone on the ruby causing some of the ruby molecules to oscillate. The molecules are then in an excited, high-energy state. However, each molecule attempts to return to its normal state. When it does so, it emits a particle of light, also known as a photon – a phenomenon that Albert Einstein had already noted in 1917. Laser light occurs when a very large number of ruby molecules are excited, because they can stimulate each other when they return to their initial state.

As of 1960, the first solid-state and gas lasers were built by Nikolai Gennadiyevich Basov and Alexander Mikhailovich Prokhorov in the Soviet Union and Maiman and All Javan in the United States. The semiconductor laser followed in 1962 and the dye laser some time later.

Today, lasers have become a vital component in many areas of technology. This includes the field of medicine in which laser applications are used every day, ensuring the precision of surgical techniques and treatments. The concentrated artificial light also allows minimal invasiveness; limited side-effects and is therefore especially gentle on the patient.

Intensive laser beams can cut through and cauterise human tissue in fractions of a second without damaging the surrounding tissue. A huge variety of conditions can be treated safely and effectively from vasodilatation to carcinomas of the liver. Over three million eye operations involving laser therapy are performed each year worldwide.