Light and Shadow

How we learned to rein in the risks of X-rays
Comparison of the two hand X-rays from Gerrit Kemerink’s experiment: on the left, the image taken with the 1896 apparatus; on the right, the image captured with a modern X-ray unit from 2010
Comparison of the two hand X-rays from Gerrit Kemerink’s experiment: on the left, the image taken with the 1896 apparatus; on the right, the image captured with a modern X-ray unit from 2010 

Source: Prof. Gerrit Kemerink, Department of Radiology, Maastricht University Medical Center

In 2010, the Dutch radiologist Gerrit Kemerink X-rayed a hand at Maastricht University Medical Center. There wouldn’t normally be anything unusual about that – except that this was the hand of a dead body and Kemerink was using an X-ray unit from 1896. Recorded in a darkened room, the images turned out “surprisingly well” and offered a clear depiction of the hand’s anatomical details. However, his measurements during the examination using the historical apparatus indicated a radiation dose of 75 mSv, which is 1,500 times that of a comparable examination with modern equipment. In those days, capturing just a single X-ray image resulted in 75 times the recommended annual dose for a normal person today. This highlights the fact that early operators and patients were exposing themselves to enormous doses in a very short space of time. It was a far cry from our current knowledge of X-rays and their responsible use.

Röntgen’s discovery was followed by a huge wave of euphoria. Numerous physicists, technicians, and physicians around the world began experimenting with X-rays. At this stage, however, the handling of the rays was extremely unsophisticated, as no one had any idea of the dark side of this new radiation. Particularly in medicine, X-rays were used as a diagnostic tool to search for diseases, but the examinations in that era only distantly resembled the ones we’re familiar with today.

Portable X-ray unit with a freely suspended tube, 1903
Portable X-ray unit with a freely suspended tube, 1903
 The atmosphere in many turn-of-the-century medical practices was more like that of a living room. The patient assumed the examination position, the physician switched on the X-ray equipment with the X-ray tube hanging freely in its bracket, and the entire room was flooded with radiation. The examination could take anything from minutes to hours, during which the physician and patient were completely unprotected from the rays.

Although reports soon emerged of harmful effects of X-rays, such as hair loss or sunburn, these skin reactions were not taken seriously at first. Indeed, some even thought that the rays offered an ideal way of removing unwanted hair, an observation that soon led to the development of radiation therapy.

Early X-ray damage to the hands of the 28-year-old RGS employee Otto Schreiber in an image taken in 1910
Early X-ray damage to the hands of the 28-year-old RGS employee Otto Schreiber in an image taken in 1910

It was only at a later stage that the serious harm became clear – and it was especially prominent in those who were frequently exposed to the rays: physicians, nurses, and workers involved in the production of X-ray units. In these individuals, what began as reddening of the skin developed into a chronic illness that could be alleviated but not cured. The radiographer Otto Schreiber was one of those affected. Schreiber worked at Reiniger, Gebbert & Schall (RGS) in Erlangen from 1907 onward and was tasked with improving the company’s radiographic technology. This meant that his hands were frequently exposed to radiation, and the first radiation damage appeared in 1909.

Various X-ray accessories for radiation protection from Reiniger, Gebbert & Schall: radiation-protected cabins, radiation protective screens, protective aprons and gloves, protective cases for the tube, leaded glasses, etc., 1905–1910
Various X-ray accessories for radiation protection from Reiniger, Gebbert & Schall: radiation-protected cabins, radiation protective screens, protective aprons and gloves, protective cases for the tube, leaded glasses, etc., 1905–1910

Things slowly started to change between 1900 and 1910, when the carefree use of X-rays began to claim its first victims. The skin damage often developed into cancer, bringing the lives of many pioneers in radiology to a premature end. In 1924, at the age of just 37, Otto Schreiber also died of the effects of excessive radiation exposure. Research increasingly focused on the subject of radiation protection, which was a key topic at the first German Radiology Congress in 1905. Some protective equipment was developed and made commercially available.

The Dr. Schilling test hand, consisting of the skeleton of a hand cast in wax with a leather cover to imitate a human hand, RGS catalog, 1907
The Dr. Schilling test hand, consisting of the skeleton of a hand cast in wax with a leather cover to imitate a human hand, RGS catalog, 1907

One such tool was Dr. Schilling’s X-ray test hand, which allowed physicians to test whether the X-ray unit was set up correctly and a good image would be obtained. Prior to this, physicians would test the setup on their own hands. People also began to protect themselves using radiation-proof clothing, such as gloves and aprons made of leather or leaded rubber. Physicians put together entire radiation-protection suits, which resembled a suit of armor and were often frightening for patients.

The industry also offered mobile X-ray protective screens with lead-glass windows or radiation-protected cabins, which the physician or nurse could sit behind or inside to protect themselves from the radiation. The exposed tubes were also gradually covered and fitted with apertures so that only the concentrated cone of radiation was allowed to escape.

Many of these protective measures remain just as current today. The patient and physician still wear protective aprons, and the operating personnel normally leave the examination area while the image is captured. These areas are now also separated into different rooms. The tube is no longer suspended freely in the room, but instead contained inside a radiation-proof housing. An aperture opens for a mere fraction of a second to allow only as much radiation to escape as is necessary for the current examination, practically eliminating the risk of direct radiation damage.

The drastic reduction in exposure time was instrumental in achieving radiation protection. For example, the average exposure time for a hand decreased from between 15 and 20 minutes in 1896 to between 0.25 and 0.5 seconds in 1913. Today, it takes just a few milliseconds.

Monitoring software on modern CT scanners helps to optimize the examination in order to minimize the radiation dose, 2017
Monitoring software on modern CT scanners helps to optimize the examination in order to minimize the radiation dose, 2017

Since the 1920s, it has also been possible to measure the exact radiation dose and to work toward reducing radiation exposure. Numerous technical improvements in X-ray equipment over the last 124 years – from better photographic technology to more powerful X-ray tubes – have also led to a reduction in exposure times and radiation dose. The advent of digital technology in the 1970s and 1980s opened up innovative new ways to significantly lower the dose, with major achievements in the field of computed tomography (CT) in particular. Launched in 2014, SOMATOM Force could produce scans of a lung in uncompromised image quality with a dose of just 0.1 mSv, which roughly corresponds to the natural radiation dose received on a flight from Germany to Argentina. In general, the benefits of a radiological examination far outweigh the slight risks that still exist today.