X rays are what type of energy

Rep Carcinog. American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy. Download this topic [PDF]. What Are X-rays and Gamma Rays? Doses of radiation Radiation exposure can be expressed in certain units.

Less common radiation dose units include rads, rems, and roentgens. Written by References. The American Cancer Society medical and editorial content team Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Figure 2. Theoretical x-ray spectrum before filtration. There are more low energy photons than high energy photons. Print Save your progress. Your session is about to expire. The only difference between them is their source: X-rays are produced by accelerating electrons, whereas gamma-rays are produced by atomic nuclei in one of four nuclear reactions. Some form of energy was being produced by the tube that was penetrating the paper and causing the crystals to glow. X-rays can be produced on Earth by sending a high-energy beam of electrons smashing into an atom like copper or gallium, according to Kelly Gaffney, director of the Stanford Synchrotron Radiation Lightsource.

When the beam hits the atom, the electrons in the inner shell, called the s-shell, get jostled, and sometimes flung out of their orbit. Without that electron, or electrons, the atom becomes unstable, and so for the atom to "relax" or go back to equilibrium, Gaffney said, an electron in the so-called 1p shell drops in to fill the gap.

The result? An X-ray gets released. It's not a very easy way to make a high-energy, bright source of X-rays.

Enter a synchrotron, a type of particle accelerator that accelerates charged particles like electrons inside a closed, circular path. Basic physics suggests that any time you accelerate a charged particle, it gives off light. The type of light depends on the energy of the electrons or other charged particles and the magnetic field that pushes them around the circle, Gaffney said. This property can be used to identify elements, for example, to find trace small amounts of an element in an environmental or biological sample.

Figure 2. A characteristic x ray is emitted when an electron fills an inner-shell vacancy, as shown for several transitions in this approximate energy level diagram for a multiple-electron atom. Characteristic x rays are labeled according to the shell that had the vacancy and the shell from which the electron came. How do we calculate energies in a multiple-electron atom? In the case of characteristic x rays, the following approximate calculation is reasonable. Characteristic x rays are produced when an inner-shell vacancy is filled.

Inner-shell electrons are nearer the nucleus than others in an atom and thus feel little net effect from the others. This is similar to what happens inside a charged conductor, where its excess charge is distributed over the surface so that it produces no electric field inside. It is reasonable to assume the inner-shell electrons have hydrogen-like energies, as given by. As noted, the effective Z is This large photon energy is typical of characteristic x rays from heavy elements. It is large compared with other atomic emissions because it is produced when an inner-shell vacancy is filled, and inner-shell electrons are tightly bound.

Characteristic x ray energies become progressively larger for heavier elements because their energy increases approximately as Z 2.

Significant accelerating voltage is needed to create these inner-shell vacancies. In the case of tungsten, at least Tungsten is a common anode material in x-ray tubes; so much of the energy of the impinging electrons is absorbed, raising its temperature, that a high-melting-point material like tungsten is required.

All of us can identify diagnostic uses of x-ray photons. Among these are the universal dental and medical x rays that have become an essential part of medical diagnostics. See Figure 4 and Figure 5. X rays are also used to inspect our luggage at airports, as shown in Figure 3, and for early detection of cracks in crucial aircraft components. An x ray is not only a noun meaning high-energy photon, it also is an image produced by x rays, and it has been made into a familiar verb—to be x-rayed.

Figure 3. Figure 4. The most common x-ray images are simple shadows. Since x-ray photons have high energies, they penetrate materials that are opaque to visible light. The more energy an x-ray photon has, the more material it will penetrate.

So an x-ray tube may be operated at The depth of penetration is related to the density of the material as well as to the energy of the photon. The denser the material, the fewer x-ray photons get through and the darker the shadow. Thus x rays excel at detecting breaks in bones and in imaging other physiological structures, such as some tumors, that differ in density from surrounding material. Because of their high photon energy, x rays produce significant ionization in materials and damage cells in biological organisms.

Modern uses minimize exposure to the patient and eliminate exposure to others. Biological effects of x rays will be explored in the next chapter along with other types of ionizing radiation such as those produced by nuclei.

Figure 5. This x-ray image shows the contents of a piece of luggage.