Roentgen Ray Tube

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The early development of x-ray technology, beginning with the Roentgen Ray Tube in 1895, can be seen as a new way of engaging with problematic boundaries between materiality and its representations, as well as between the inside and the outside of an enclosed body. The ability to project the inside of the patient's body out onto a screen was made possible by a tube called a Crookes Tube that emitted radiation as a side effect. In fact the tube was designed precisely to do the opposite, to contain experiments with electricity within the tube's glass walls. The externalization of electromagnetic radiation from a Crookes Tube would become central to subsequent technical developments of the tube, which turned into a Roentgen Ray, or X-Ray Tube, the new name characterizing an emphasis on the projected image rather than on the electrical lighting effects internal to the tube.

While experimenting with a Crookes Tube, a partially evacuated gas tube used to study the passage of electrical currents through gases[1], a German professor named Wilhelm Conrad Röntgen saw a luminescence in the darkened room outside of the tube. This despite the fact that he had surrounded the glass tube in cardboard that had been painted black (presumably to prevent light from entering the tube). He realized that this effect was caused by an unknown form of radiation (hence the denotation he gave it, "X") emitted by an electrical current passing through the tube and hitting the anode, or the positive electrode. The radiation had created a luminescent shimmer on a piece of paper painted with a chemical that made it act like photo paper, something Röntgen had been using in his photography experiments.

Röntgen and the people for whom he demonstrated his discovery were amazed not only that the rays could pass through glass, but also that they had passed through the cardboard, an object opaque to light, while glass is impermeable to air molecules. The x rays had traversed the boundaries of the tube, and soon proved able to pass through various solid substances, including flesh and blood. This mode of representation materially impinges on the matter of its objects, as well as the matter that makes it possible: the atoms of gas inside the tube. The difficulty of regulating gas pressure got in the way of the clarity of the image, which compromised the human ability to read it. The partially evacuated gas tube thus became obsolete when it was replaced by a vacuum tube. The death of the gas tube can be seen as the birth of free energy, or energy that does not not need a material substrate in order to occur.

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An x ray of Bertha Röntgen's hand.
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Picture taken during the demonstration of the Röntgen Rays at the meeting of the American Philosophical Society held February 7, 1896. The picture is of a key and coins inside a pocketbook. (Proceedings of the American Philosophical Society, 1896)

A Material Act of Representation

From a critical perspective, the entrance of x rays into medical history can be read as an intrusion of the scientific gaze into the body, or, alternatively, as an impingement of technology onto the body that functions to bring the body's interior, hidden space, to an external space exposed to vision. To view it in this second way, as a technical externalization of the body's insides, is to address the materiality of the act of representation. This is a useful way to think of x-ray technology in which electromagnetic radiation (a form of energy) goes through solid matter in order to produce a picture. Unlike in photography, which is based on the reflection of light off a solid object, skin subjected to an x ray transducts the radiation. The materiality of the act of representation becomes clearer when one considers radiation's effects on the body. While these effects were first viewed as an unfortunate side effect, the power of radiation to affect the body (for better or worse) was harnessed by both medicine and technologies of war and security.

The Side Effect

Radiation was at first an accidental effect of the technical act of representation, but its ability to materially affect the body branched off into its own field. Diagnostic X rays are still used in medicine, but radiation has also become detached from representation and diagnosis and moved into the realm of treatment. Its known ability to kill cells has been turned against cancer cells that are trying to kill the organism as a whole. In other words the deadly radiation is used as a weapon against death on the side of life. This exemplifies part of Michel Foucault's argument in Birth of the Clinic, about the undermining of the duality between life and death that takes place during the rise of modern medicine's examination of the body (Foucault). Foucault argues that before this the organism was seen merely as the "seat" of a disease; the disease's essence had nothing to do with its occurrence in a body. Modern medicine, in contrast to this, "maps" the disease onto the body, such that the life of the disease is understood to be made possible by the life of the organism in which it grows. Therefore life and death are sometimes conflated, or mapped onto each other.

Additionally, the link between life and death is seen in the reading of x rays, which required knowledge of the skeleton that must have been gleaned from actual skeletons and corpses. The knowledge of the dead provided a norm against which to compare the aberration. When Wilhelm Rontgen x-rayed his wife, Bertha's, hand, she said that she had glimpsed her death. Popular jokes and cartoon references to Rontgen Rays also spoke to the association between x rays and death.

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Life Magazine, 1896

The Bullet V. the Gun

Roentgen Ray Tubes were used in World War I to locate bullets and shrapnel in the bodies of wounded soldiers. Now x-ray technology as a mode of representation seems to be developing more in the field of national security than in medicine. Instead of x-raying a wounded body in search of a bullet, we are x-raying luggage in search of weapons. This follows from the relationship between x rays and the blurred boundary between the outside and the inside of a body; a bullet coming from outside penetrates the body and an x ray locates it in order to remove it, to bring it back to the outside of the body from whence it came. X-raying luggage also represents a search for an external enemy in what is supposed to be an interior, private space (i.e. a suitcase of personal belongings). The suitcase is not the body, but an extension of the body, a collection of things necessary enough to be brought with the body wherever it goes. On another register, the terrorist is understood to be an external enemy who has slipped into an interior space. X rays used for securitization serve the end of removing the enemy from the internal space of the country or the liminal space of travel between national/state borders.

Technical Concerns: The Development of the High Vacuum Tube

The technical development of the Roentgen Ray Tube aimed for higher predictability in x ray images, which would result in the removal of gas as the material matrix of x-ray production. Eventually, the partially evacuated gas tube was replaced by a high vacuum tube developed by Julius Edgar Lilienfeld. The significance of the high vacuum tube is that "It enabled the tube to... make x-ray production and x-ray energy independent of gas pressure" (Arns, 864). This can be framed as a detachment of energy from concrete matter in the sense that atoms of gas can be understood as material things. The vacuum tube isolates electrical energy in that affectations of electrons are separated from atoms. It seems to be a first capture of pure excitation, already bridging the gap between the material of the body and its representation on a piece of film.

The Temperamental Tube

While the gas inside the tube made the x rays possible, it was an enemy of predictability because of the difficulty in quantifying and measuring the movement of its atoms. Much discussion of gas tubes focuses on their unreliability. The clarity of the images they produced was erratic because their efficiency depended on a delicate balance between gas pressure and electrical voltage, not to mention that the production of the glass tubes was not yet standardized (Arns, 861). "Because the early tubes were highly erratic in their production of x-rays, research became centered upon their improvement. With these gas tubes there was a constant tendency for the gas to be absorbed into the solid parts of the tube; the tube might leak; it required as much art to produce x-rays as to read the resulting x-ray films. Some method was needed to make a stable tube whose output could be relied upon and would permit standardization in exposure technique" (Bleich, 19). The unreliability of the tubes justified the need for skilled readers who were trained in radiography. It also presented the need for a tube that did not wear out as quickly. Repeated excitation of the gas inside the tube caused a clouding or staining of the glass near the anode (towards which the electrons were fired). This cloudiness blocked "soft" or weaker x rays, so that only "hard" x rays could make it through the tube. This limited the effectiveness of the x rays to substances that were not at all permeable to x rays, thus limiting the range of possibilities.

Maxwell's Demon

In addition to its "temperamental" ability to represent clear images, the gas tube easily ran out of gas (Arns, 861). This can be seen as part of the effort to keep generating energy without running out of fuel, or, in this case, using up all of the free floating atoms of gas in the tube. As always, technical difficulties relate to economic convenience, and in the case of the gas tube, there was an effort to find a way for the tube to automatically regenerate its gas supply. The first solution to this was to attach a side tube containing a chemical that, when heated with a match, would spread into the main chamber to replenish the gas supply (Arns, 861). Then this process became automatic so that low gas pressure sent a spark into the side tube that heated the gas, so that the labor of the attendant was no longer necessary. Eventually, this problem was solved by more completely freeing energy from the material matrix of gas in the form of the vacuum tube.

The High Vacuum Tube

The difficulties of managing gas pressure and loss of gas slowed down medical and radiological interest in x rays, which seemed to be more trouble than they were worth. This problem was solved by Arthur Wehnelt's 1904 discovery of "thermionic emission," which means "the freeing of electrons from the surface of a heated solid" (Arns, 862). Lilienfeld employed a Wehnelt cathode in his early version of the high vacuum tube, eventually developed into a true vacuum tube (containing no gas at all) by William David Coolidge (Arns, 868). The Coolidge tube no longer needed any gas in order to conduct a current; instead a solid piece of metal was excited until electrons began to escape it and move through the vacuum tube. There was literally no material matrix for the electric current to move through. Electrons detached from atoms moved through empty space.

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A gas x-ray tube with a side tube for regenerating gas. "The regeneration mechanism D was activated when the gas pressure in the tube became so low that a spark jumped between E and F" (Arns, 862).


Taking an x ray picture is an act of enframing. Not only does it zero in on and frame a specific part of the skeleton, but it also brings forth the skeletal frame from the rest of the body. In other words, it is an observation that engages in analysis. Even before a human radiologist interprets and analyzes the picture, the actual x-ray machine performs an act of analysis by capturing only the bones in the picture, thereby extracting the skin, blood, and muscle from the image. In a paper presented at the 2008 Eastern Sociology Society Meeting, Sam Han discussed Heidegger's understanding of enframing “But for Heidegger specifically, to call something a ‘world’ is to identify a process of binding and cohesion; thus it is a normative claim” (Han 2008).

X-ray technology is still used in medicine, but many medical sociologists cite a shift in focus in medical technology from representational images to statistical modeling. "The digital image is obviously a computer-generated image, which Stiegler often calls the 'calculated image,' in that it models the real, yet imitates it quasi-perfectly" (Han 2008). The calculated image might alternatively be understood to imitate the real "hyper-perfectly," or, in other words, to create a representation that better resembles the statistical norm. In recent years some aspects of the role of x-ray reader have been passed over to technology. The job of interpreting the image became subsumed by computer imaging technologies, which are able to sharpen images and increase contrasts, thereby removing some of the vagueness that requires a skilled human reader to decipher. For aspects of physical health that are difficult to x-ray, models are used to predict a patient's chance of having a certain abnormality. The digital model does not impinge on the body like radiation does. As Han writes, "By suggesting that the discrete image serves an an epokhe, Stiegler is arguing that what is produced in an image by digital technologies is not necessarily "captured" (Han 2008). This idea that the digital image does not "capture" the object gives us terms to discuss the relationship between the internal, private(?) space, and its representation.

The Technical Invasion of Privacy

The technical invasion of the body led to associations between x rays and sexual impropriety. It is interesting to note that technology was not viewed as neutral, or purely scientific, even though there was mass support for it. On another level of the cultural imagination, perhaps mostly in humor, the device triggered a sense of exposure: “The apparel of a well-to-do Victorian lady seems to us today to have been used to deny the reality of flesh and blood. The idea that it might be made transparent by the use of x-rays may have been the first intimation of what we now consider the sexual revolution of the 20th century. The established social order, as well as public morality, had come under technological “threat” (Lentle, 513)

Many cultural references to Roentgen Rays demonstrated an understanding of Roentgen Rays as an invasion of privacy, such as advertisements for "x-ray proof underclothing" (Bleich, 6). The following poem from the magazine, Photography, playfully refers to the inappropriate gaze of the x ray:

"The Roentgen Rays, the Roentgen Rays,/ What is this craze:/ The town's ablaze/ With the new phase/ Of x-ray's ways./ I'm full of daze,/ Shock and amaze,/ For now-a-days/ I hear they'll gaze/ Thro' cloak and gown-- and even stays,/ These naughty, naughty Roentgen Rays."/ (Bleich, 6).

This poem equates Roentgen Rays with a voyeuristic, lascivious gaze. The idea that the Rays could see through clothes seemed to be a source of titillation, perhaps associated with anxiety about female sexuality. The following poem by Lawrence K. Russel, published in Life Magazine, March 12, 1896, comically describes a woman's skeleton as beautiful and sexually appealing:

She is so tall, so slender; and her bones-- Those frail phosphates, those carbonates of lime-- Are well produced by cathode rays sublime; By oscillations, amperes and by ohms, Her dorsal vertebrae are no concealed By epidermis, but are well revealed.

Around her ribs, those beauteous twenty-four, Her flesh a halo makes, misty in lime, Her noseless, eyeless face looks into mine, And I but whisper, "Sweetheart, je t'adore." Her white and gleaming teeth at me do laugh, Ah! lovely, cruel, sweet cathodagraph!

While these references seem relatively light-hearted, from the perspective of today when x rays are not only used on patients (who consent) to look at the physiology of the body, but are also used on potential suspects (who are required to submit their belongings and clothing to x-ray scrutiny), this early fear takes on a more ominous tone. It seems to be a premonition of x rays used for surveillance.

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Advertisement of "the perfect dress interlining" from The Globe, Toronto, Feb. 27, 1896 (Lentle, 513).


Arns, Robert G. The High-Vacuum X-Ray Tube: Technological Change in Social Context. Technology and Culture vol. 38, no. 4: 852-890.

Bleich, Alan R. 1960. The Story of X-Rays from Röntgen to Isotopes. New York: Dover Publications, Inc.

Golan, Tal. 2004. The Emergence of the Silent Witness: The Legal and Medical Reception of X-rays in the USA. Social Studies of Science vol. 34, no. 4: 469-499.

Foucault, Michel. 1994. The Birth of the Clinic: An Archaeology of Medical Perception. Trans. A.M. Sheridan Smith. New York: Vintage Books.

Han, Sam. 2008. Is the Global Really Glo-bile? Image-ing the 'World Picture' in an Age of Mobile Onto-Aesthetics. Paper presented at Eastern Sociological Society Meeting, February 24th, in New York.

Lentle, Brian. 2000. X-rays and technology as metaphor. Canadian Medical Association Journal 162 (4): 512-514.

Pasveer, Bernike. 1989. Knowledge of shadows: the introduction of X-ray images in medicine. Sociology of Health & Illness 11(4): 360-383.

"Remarks Made at the Demonstration of the Rontgen Ray, at Stated Meeting, February 21, 1896." Proceedings of the American Philosophical Society 35 (150): 17-36.