Discovery of X-Rays

German physicist Wilhelm Röntgen is usually credited as the discoverer of X-rays in 1895, because he was the first to systematically study them, though he is not the first to have observed their effects.

X-rays were found emanating from Crookes tubes, experimental discharge tubes invented around 1875, by scientists investigating the cathode rays, that is energetic electron beams, that were first created in the tubes. Crookes tubes created free electrons by ionization of the residual air in the tube by a high DC voltage of anywhere between a few kilovolts and 100 kV. This voltage accelerated the electrons coming from the cathode to a high enough velocity that they created X-rays when they struck the anode or the glass wall of the tube.

In the 1880s, both William Crookes and German physicist Johann Hittorfa co-inventor and early researcher of the Crookes tube, found that photographic plates placed near the tube became unaccountably fogged or flawed by shadows. Neither found the cause nor investigated this effect.

In 1877 Ukrainian-born Ivan Pulyui, a lecturer in experimental physics at the University of Vienna, constructed various designs of vacuum discharge tube to investigate their properties.He continued his investigations when he was appointed a professor at thePrague Polytechnic and in 1886 he found that sealed photographic plates became dark when exposed to the emanations from the tubes.

On November 8, 1895, German physics Professor Wilhelm Röntgen stumbled on X-rays while experimenting with Lenard and Crookes tubes and began studying them. He wrote an initial report “On a new kind of ray: A preliminary communication” and on December 28, 1895 submitted it to the Würzburg’s Physical-Medical Society journal.This was the first paper written on X-rays. Röntgen referred to the radiation as “X”, to indicate that it was an unknown type of radiation. The name stuck, although (over Röntgen’s great objections) many of his colleagues suggested calling them Röntgen rays. They are still referred to as such in many languages, including German, Danish, Polish, Swedish, Finnish, Estonian, Russian, Japanese, Dutch, and Norwegian. Röntgen received the first Nobel Prize in Physics for his discovery.

It is interpreted that Röntgen was investigating cathode rays using a fluorescent screen painted with barium platinocyanide and a Crookes tube which he had wrapped in black cardboard so the visible light from the tube would not interfere. He noticed a faint green glow from the screen, about 1 meter away. Röntgen realized some invisible rays coming from the tube were passing through the cardboard to make the screen glow. He found they could also pass through books and papers on his desk. Röntgen threw himself into investigating these unknown rays systematically. Two months after his initial discovery, he published his paper.
Röntgen discovered its medical use when he made a picture of his wife’s hand on a photographic plate formed due to X-rays. The photograph of his wife’s hand was the first photograph of a human body part using X-rays.

History of X-rays

Definition Of X-Radiation:

X-radiation is a form of electromagnetic radiation, having wavelengths ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV. X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays.

Constituents of X-radiation

The major components of an X-ray generator are the tube, the high voltage generator, the control console, and the cooling system. In this material, X-rays are generated by directing a stream of high speed electrons at a target material such as tungsten, which has a high atomic number. When the electrons are slowed or stopped by the interaction with the atomic particles of the target, X-radiation is produced. This is accomplished in an X-ray tube such as the one shown here. The X-ray tube is one of the components of an X-ray generator and tubes are available in a variety of shapes and sizes. The image below shows a portion of the Roentgen tube.

Advances in X-Ray generation

In 1895, Thomas Edison investigated materials’ ability to fluoresce when exposed to X-rays, and found that calcium tungstatewas the most effective substance. Around March 1896, the fluoroscope he developed became the standard for medical X-ray examinations. Nevertheless, Edison dropped X-ray research around 1903, even before the death of Clarence Madison Dally, oneof his glassblowers. Dallyhad a habit of testing X-ray tubes on his hands, and acquired a cancer in them so tenacious that both arms were amputated in a futile attempt to save his life.

In 1901, U.S. President William McKinley was shot twice in an assassination attempt. While one bullet only grazed hissternum, another had lodged somewhere deep inside his abdomen and could not be found. “A worried McKinley aide sent word to inventor Thomas Edison to rush an X-ray machine to Buffalo to find the stray bullet. It arrived but wasn’t used.” While the shooting itself had not been lethal, “gangrene had developed along the path of the bullet, and McKinley died of septic shock due to bacterial infection” six days later.

The first use of X-rays under clinical conditions was by John Hall Edwards in Birmingham, England on 11 January 1896, when he radio graphed a needle stuck in the hand of an associate. On 14 February 1896 Hall-Edwards was also the first to use X-rays in a surgical operation.In early 1896, several weeks after Röntgen’s discovery, Ivan RomanovichTarkhanov irradiated frogs and insects with X-rays, concluding that the rays “not only photograph, but also affect the living function”.

The first medical X-ray made in the United States was obtained using a discharge tube of Pulyui’s design. In January 1896, on reading of Röntgen’s discovery, Frank Austin of Dartmouth College tested all of the discharge tubes in the physics laboratory and found that only the Pulyui tube produced X-rays. This was a result of Pulyui’s inclusion of an oblique “target” of mica, used for holding samples offluorescent material, within the tube. On 3 February 1896 Gilman Frost, professor of medicine at the college, and his brother Edwin Frost, professor of physics, exposed the wrist of Eddie McCarthy, whom Gilman had treated some weeks earlier for a fracture, to the X-rays and collected the resulting image of the broken bone on gelatin photographic plates obtained from Howard Langill, a local photographer also interested in Röntgen’s work.

How do X-Rays Work?

X-rays were found to be able to penetrate through materials of light atoms like flesh. The heavier atoms like metal absorb them. A beam of high energy electrons crashes into a metal target and x-rays are produced. A filter near the x-ray source blocks the low energy rays so only the high energy rays pass through a patient toward a sheet of film. Along with the sheet of film, a second sheet of film prevents the scattered x-rays from fogging the picture. Calcium in bones is considered a type of metal and when photographic film is placed on the body, this allows the technician to take the picture and an x-ray is developed to solve or analyze the problem.

Much like camera film, the X-ray film develops depending on which areas were exposed to the X-rays. Black areas on an X-ray represent areas where the X-rays have passed through soft tissues. White areas show where denser tissues, such as bones, have absorbed the X-rays.

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Precautions to be taken while using / getting exposed to X-Rays

X-ray Safety Measures for Health Workers:

Radiation exposure to technologists, nursing staff, physicians, and to others must be kept as low as reasonably achievable.

Only personnel who are required for the x-ray procedures or training should be present in the x-ray room during exposures.

Health workers should use portable or fixed lead panels or use the following PPE (Personal Protective Equipment):

– Lead aprons.
– Lead safety glasses.
– Thyroid shield.
– Leaded gloves.

Keep the time of radiation exposure short, especially during fluoroscopic procedures.

Follow proper techniques to minimize the number of repeat exposures.

Staff should not routinely hold patients. Use mechanical holding devices when a patient or film requires added support. If that is not possible, patients should be held by a relative or friend who is wearing lead aprons and gloves.

If pregnant, notify the head of your department.

X-ray Safety Measures for Patients:

X-ray radiation exposure to patient should be kept as low as possible.

The radiation exposure to the patient should be minimized without on the diagnostic quality of the exam.

Follow the proper technique for each examination—this reduces the need to repeat the procedure.

Obtain a good quality radiograph the first time and reduce the number of repeat examinations.

Align the primary x-ray beam to the area of interest to reduce radiation.

When portable x-ray machines are used, ensure that other patients are located at least one meter away from radiation or utilize portable lead panels.

Identify pregnant patients and notify the referring physician before they undergo any x-ray examination.

Use protective eye wear and aprons when appropriate.

Testimonials for Digital X-ray

Digital X-ray provides benefit for patients and dentists reducing radiation exposure and eliminating the hazards associated with processing chemicals. Image acquisition, viewing, storage, and retrieval improves clinical diagnosis and patient consultations, making each procedure more efficient.

I am a dentist and I have experienced that digital detectors make an interactive dentist/patient relationship. The instant image captured, enables the dentist to discuss the treatment plan with the patient and the patient readily visualize the need for treatment.

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Case Study in Dentistry

There were two childhood friends, Ashish and Monika who decided to make their career in Dentistry. Both of them took admission in Maulana Azad Institute of Dental
Sciences, Pune.

After graduating, they joined different hospitals for dental practice. Their practice continued for few years and on completion, they opened their own dental clinic.

Ashish started his dental clinic with film based technology of X-ray. He used Traditional X-ray involving film, chemicals, fresh water, etc. to attend patients. Through this method of X-ray, he was able to attend only a few number of patients daily.

Monika started her clinic by using Digital Intraoral X-ray Sensors, even though it was expensive. She used Digital X-ray which is free from any film, chemicals, fresh water, etc. to attend patients. Handling patients through Digital X-ray delighted her and her patients. She was able to handle more patients with complete details and became strong using this technology.

After a long time, these two friends met in an International Conference on Dentistry and they shared their life experiences with each other. Ashish came to know that the digital detectors are far better than traditional detectors because of the following features:

– The X rays taken from digital detectors are immediately processed and available to view, whereas film based on traditional detectors take time to develop.
– Less radiation is needed for digital detectors to produce the same quality image as compared to traditional detectors (digital X-rays gives 70% less exposure to radiation than conventional X-rays).
– The digital images can be enhanced (such as alter brightness and contrast) with a series of processing techniques.
– Digital archiving—the ability to store images on a computer.
– Digital detectors produce large photos to better identity hard-to-see cavities.
– Digital detectors, though expensive to buy initially, are cheaper and more environmentally friendly in the long run.

Now, Ashish treats his patients with Digital Detector and handles more number of patients than before and has also become financially strong.