Making visible

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Doctors and natural scientists have long been interested in the inside of the body. But for centuries they had to open the body to do so, or they could only infer the shape and functioning of the interior indirectly, for example, through the senses of touch and hearing. The discovery of X-rays triggered a medical revolution. For the first time, doctors were able to look inside the living body. X-ray technology quickly spread not only as a diagnostic but also as a therapeutic method and forms the basis for further imaging procedures. Today, images and films about processes inside the body shape not only research, diagnosis and therapy, but also the public perception of medicine.

X-ray revolution

On 8 November 1885, an unknown physicist was experimenting with a cathode ray tube in Würzburg. He noticed that the rays from the tube projected objects as bright shadows on a photographic plate. Shortly afterwards, Wilhelm Conrad Röntgen informed the wider medical community for the first time about his observation of "a new kind of rays" ones which could penetrate bodies and image objects. The importance for medical diagnosis was obvious to many and the technology began spreading rapidly. But in the first few years, apparatus and tubes first had to be improved and procedures standardised.

Bernese beginnings

In Bern, it was the physicist and meteorologist Aimé Forster who produced the first X-ray images in his laboratory at the University of Bern. As early as 1896, he presented "Radiographic images performed with X-rays" and pointed out the importance of the new technology for diagnosis. Initially, the hospital surgeons also used the X-ray facilities of the Institute of Physics, before a proprietary X-ray institute was put into operation in January 1898 in an extension to the Surgical Clinic.

Image production

X-ray images do not simply depict nature. They have to be produced. To ensure the comparability of the images, the recording procedures were initially standardised in the early years. This was because sceptics pointed out that faulty settings could lead to incorrect images that could be interpreted as pathological findings. The fact that X-ray technology was able to establish itself was, therefore, also linked to the development of devices, photographic plates or fluorescent screens. The big boom enabled the emergence of smaller companies like Roewag in Bern, which assemble entire devices from individual components.

X-ray tubes

After the discovery of X-rays, various companies such as Siemens quickly specialised in the production of X-ray tubes. In these X-ray tubes, X-rays were produced in a vacuum by the impact of electrons on an anode. One of the early manufacturers was Reinhold Burger in Berlin, who, together with Wilhelm Conrad Röntgen, developed tubes for diagnosis, but soon also for therapy. His therapy tube was also used in the Bern X-ray Institute from 1913.

Read images

X-rays allowed us to see things that were previously invisible. They thus competed with the older physical examination methods. However, the meaning of the images was not self-evident. To this day, trained experts are needed to interpret the images. In the early years, physicians, physicists and technicians first had to agree on what exactly they are showing and whether they are reliable representations. From 1900 onwards, comprehensive pictorial atlases helped to correctly identify injuries and diseases.

Quite normal pictures

From 1900 onwards, various X-ray atlases appeared on the market. The X-ray images did not necessarily simply speak for themselves. They were supplemented by drawings and explanations. Between 1905 and 1939, Rudolf Grashey's "Atlas of Typical X-ray Images" was reprinted six times. In it, Grashey shows X-ray images of "normal" people without disease. They served as sample images to identify deviations – and thus diseases or injuries.


Some X-rays were difficult to decipher: In 1920, first the doctors at the Waldau Psychiatric University Hospital, then at the Inselspital, were faced with a puzzle. A patient complained of stomach complaints. In Inselspital, the doctors x-ray him – but on the picture they only vaguely recognise a black body. Only the operation would bring about clarity: The patient apparently tore his bed linen into strips, rolled them up and then ate them.


In the early 20th century, there was a great enthusiasm for radiation: There was hardly anything that was not x-rayed. Not only was a new age of diagnosis dawning for medicine, the rays were also expanding the arsenal of therapies. In the process, those involved initially underestimated the dangers, so that many people working with the new technology suffered radiation poisoning. In March 1899, for example, the X-ray institute of the Inselspital had to close briefly because the director had probably contracted "X-ray dermatitis". Only gradually were measures being taken: Patients and technicians now wore lead aprons and the X-rays were fine-tuned with the help of measuring devices.

Radiation protection

In the early stages of the X-ray procedure, radiotherapists often used their own hands to check the intensity of the rays. When it became clear that the radiation could be dangerous, the real hand was replaced by a "test hand" and from 1930 onwards, so-called dosimeters were used to precisely record the radiation dose. To minimise unwanted radiation, doctors and patients also start wearing protective lead clothing.


In 1975, the Department of Radiation Physics at the Inselspital created a "phantom" with which radiation exposure can be measured safely and precisely. It consisted of a real human skeleton placed in a transparent plastic vessel. The vessel, which is modelled on the human body, could be filled with water. Thus, the "phantom" has very similar properties to a human body.

Further development of X-ray technology

With X-rays, a diagnosis could now be established with pictures. Doctors would interpret the images and identify bone fractures or pathological changes. X-ray technology continued to develop and was also the starting point for other imaging techniques. For example, from the 1950s onwards, small mobile X-ray machines enabled internal imaging. Since the 1970s, computer-assisted cross-sectional imaging procedures have expanded diagnostic possibilities. Computed tomography, a further development of the X-ray method


In the mid-1950s, the so-called C-arm was developed – named after the C-shaped structure of the device. It is based on X-ray technology, but could be swivelled and rotated. This allowed surgeons to access images of the inside of the body during an operation. Since the 1990s, digitisation has also made it possible to store the recordings and retrieve them at any time. Recently, there have also been devices that scan the whole body within seconds to quickly detect multiple injuries.

Rotating tubes

In the course of the 1970s, X-ray technology underwent an important further development and the first clinics put computer tomographs into operation. In the process, an X-ray tube rotates around the lying patient. Detectors catch the X-rays and measure how much they are attenuated by the different organs. The computer calculates three-dimensional sectional images from this information. In 1977, the first computer tomograph was installed in the Inselspital, enabling images of the skull, and shortly afterwards the Institute of Diagnostic Radiology received the first full-body scanner.

Das Schweizer Fernsehen erklärt die Funktionsweise der Computertomografie, 1982

Probes, sound, magnets

In the second half of the 20th century, other imaging techniques were established that did not work with radiation. Sonography uses the echoes of sound waves to make tissue visible. Magnetic resonance imaging produces slice images that can be combined to form a three-dimensional image. However, the pictures do not speak for themselves. It takes the trained eye of the expert to be able to interpret them.

Magnetic Resonance Imaging

In the 1970s, the foundations of magnetic resonance imaging were laid. It uses a strong magnetic field to gain information about hydrogen atomic nuclei in the body. Mathematical processes then allow a conversion into image information. The big advantage offered by the new technology: It makes tissue and fluids visible and the patient is not exposed to radiation. The Inselspital put the first magnetic resonance tomograph into operation in 1988. The Grand Council allocated 5.2 million Swiss francs for the device and the construction of a pavilion.


Sonography is one of the most important imaging diagnostic procedures in medicine today. It uses ultrasound, which is inaudible to humans. This is reflected like an echo at the interfaces of different types of tissue. The travel time of the sound waves provides information about the distance and the strength of the reflection about the type of tissue. This information can be translated into images. As early as around 1950, the first attempts were made to use the technology, which originated in the military context, for diagnosis. But it was not until the 1980s that it became established as a standard procedure – for pregnancy examinations, for example.


For a long time, penetrating the body was the only way to directly infer structure and processes inside. Since the middle of the 19th century, various instruments have been developed for viewing the inside of the body. Ophthalmoscopes, endoscopes, laryngoscopes allow medical practicioners to look under the skin. These endoscopic methods underwent rapid development in the 20th century: They were becoming more mobile and smaller, and were linked to new recording methods. Today, they are used in numerous medical specialties and are also the prerequisite for minimally invasive procedures.

Seeing is believing

Not only medicine, but our society as a whole became strongly influenced by the use of this imaging technique. We don't just want to hear a diagnosis, we want to see it in the picture if possible. Who could forget the image of the child in the womb? Who doesn't want to look at the MRI image showing the herniated disc? With an image, we assure ourselves that we are indeed pregnant, sick or healthy. It is on the basis of this trust in the image that medicine relies when it explains its latest achievements or interventions to us.

Live in action

In 2000, Swiss television broadcast a heart operation directly from the Inselspital in Bern in a five-hour live programme. The presentation of the successful procedure not only served to educate the public, but also convey a positive image of cutting-edge medicine and Inselspital as one of its centres. The viewers could see for themselves and witness the great effort that went into the work here in the interest of the patient.

Image diversity

Since the invention of the X-ray, images have become a central part of medical examinations. Various methods open up a view into the inside of the body. Lay people often only see shadows, indistinct structures or vague outlines in the pictures. Trained experts, on the other hand, can recognise pathological changes, make a diagnosis and plan an appropriate therapy. Can you find out what there is to see?

Selective bibliography

  • Bradley, William G. (2008): History of Medical Imaging, in: Proceedings of the American Philosophical Society 152(3), p. 349–361.

  • Dommann, Monika (2003): Durchsicht, Einsicht, Vorsicht: eine Geschichte der Röntgenstrahlen, 1896-1963, Zürich.

  • Eckart, Wolfgang U. (2017): Geschichte, Theorie und Ethik der Medizin, Berlin (8).

  • Gugerli, David & Orland, Barbara (Hg.) (2002): Ganz normale Bilder, in: Historische Beiträge zur visuellen Herstellung von Selbstverständlichkeit, Zürich.

  • Landesmuseum für Technik und Arbeit in Mannheim (2014): Herzblut: Geschichte und Zukunft der Medizintechnik, Darmstadt.

  • Leu, Fritz (Hg.) (2006): Das Inselspital: Geschichte des Universitätsspitals Bern 1954-2004, Bern.

  • Powers, Jeff & Kremkau, Frederick (06.08.2011): Medical Ultrasound Systems, in: Interface Focus 1(4), Royal Society, p. 477–489.

  • Rennefahrt, Hermann & Hintzsche, Erich (1954): 1354-1954. 600 Jahre Inselspital, Bern.

  • Siemens Healthineers (2017): Geschichte der Ultraschall-Diagnostik, Erlangen.

  • Ultraschall Museum (2020): Zur Geschichte der Ultraschalldiagnostik, Neuruppin.

  • Wyss, Sabine (1995): Radiologie in Bern: 1896-1946. Bern.