|Fig. 1: X-Ray of human hand (Source: Wikimedia Commons)|
The X-ray machine has been an effective and efficient tool in advancing medical technology worldwide. Specifically, it has perpetuated the advancement of medical imaging by using light rays to provide internal images of the human body. The machine has enabled and allowed doctors to accurately diagnose and treat disease for over a century. Today, nearly 400 million medical imaging tests are performed each year, an important one being the X-Ray. By exploring how the X-Ray works, it is possible to understand not only potential risks to patients, but also ways to make X-Rays safer.
X-rays are essential to medicine because of their ability to use light rays to produce images of the human bone. In 1895, German physicist Wilhelm Rontgen first discovered the X-ray by experimenting with cathode rays. In an attempt to examine electron beams, he created an extremely powerful transformer that converted pulses of 35,000V between electrodes. By using a vacuum to remove gas and vapor from the tube, Rontgen successfully created a low-pressure cathode tube that allowed electrons to flow freely.  His next discovery was astonishing. He noticed that the light rays and electron beams penetrated through various thicknesses of solids. The radiological density of these solids determines whether the electron beams pass through the material or not; therefore, the light rays pass through skin tissue (less dense) and are absorbed in the bones (very dense).  On the night of November 8, Rontgen determined that the electron beams passed through a sheet of black paper to produce a letter on the table. He then demonstrated that the light rays passed through a playing card, a thick book, a piece of lead, and outlined the bones of the human hand (Fig. 1).  This invention changed the field of medical imaging as it introduced the ability to capture images of the internal human body.
Considering the wide use of X-rays around the world, examining the dangers of the machines can help make medical imagining both safer and more effective for patients. The principle concern includes excess radiation exposure; intense radiation can cause cell mutations. This is especially dangerous for pregnant women, whose fetus is still developing. In the case of dental X-rays, the possibility of a pituitary or thyroid link in low birth weight infants owing to maternal exposures to low levels of dental X-rays justifies the scrutiny of exposures in maxillofacial imaging.  By understanding the risks of radiation exposure, it is possible to understand methods used to prevent it.
The best way to decrease risks of radiation is to limit the dose and control the levels of radiation.  The three basic ways to external exposure to radiation include:
A lead garment can be used as a form of shielding because it helps reduce the radiation dose that the body is exposed to. As a human bone is dense, the thick lead garment helps absorb the beam of electrons and therefore limits the risk of over exposure. Additionally, doctors recommend that pregnant women use an alternative form of medical imaging, such as an ultrasound.
In conclusion, the X-rays ability to examine the human body from an internal perspective is revolutionary, as it has spurred the discovery of imaging human bones. Ultimately, the machine has proven to be an essential medical diagnostic tool both in past times and today.
© Maggie Nick. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 G. Farmelo, "The Discovery of X-rays," Scientific American 273, No. 5, 86 (November 1995).
 T. S. Lawrence, R. K. T Haken, and A. Giaccia, "Principles of Radiation Oncology," in Cancer: Principles and Practice of Oncology, 10th Ed., ed. by V. T. DeVita Jr., T. S. Lawrence, and S. A. Rosenberg (Lippincott, Williams and Wilkins, 2014).
 K. Sansare, V. Khanna, and F. Karjodkar, "Early Victims of X-rays: A Tribute and Current Perception," Dentomaxillofac. Rad. 40, 123 (2011).
 "Analytical X-Ray Safety Workbook," University of California, Santa Cruz, July 2001, pp. 3-9.