There is no consensus for a definition distinguishing between X-rays and gamma rays. One common practice is to distinguish between the two types of radiation based on their source: X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus. This definition has several problems: other processes also can generate these high-energy photons, or sometimes the method of generation is not known. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength, equivalently, frequency or photon energy), with radiation shorter than some arbitrary wavelength, such as 10⁻¹¹ m, defined as gamma radiation. This criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. However, these two definitions often coincide since the electromagnetic radiation emitted by X-ray tubes generally has a longer wavelength and lower photon energy than the radiation emitted by radioactive nuclei. Occasionally, one term or the other is used in specific contexts due to historical precedent, based on measurement (detection) technique, or based on their intended use rather than their wavelength or source. Thus, gamma-rays generated for medical and industrial uses, for example radiotherapy, in the ranges of 6–20 MeV, can in this context also be referred to as X-rays.

The probability of a photoelectric absorption per unit mass is approximately proportional to Z³/E³, where Z is the atomic number and E is the energy of the incident photon. This rule is not valid close to inner shell electron binding energies where there are abrupt changes in interaction probability, so called absorption edges. However, the general trend of high absorption coefficients and thus short penetration depths for low photon energies and high atomic numbers is very strong. For higher atomic number substances this limit is higher. The high amount of calcium (Z = 20) in bones, together with their high density, is what makes them show up so clearly on medical radiographs. A photoabsorbed photon transfers all its energy to the electron with which it interacts, thus ionizing the atom to which the electron was bound and producing a photoelectron that is likely to ionize more atoms in its path.

Journal of Imaging and Interventional Radiology is the peer-reviewed journal of choice for interventional radiologists, radiologists, cardiologists, vascular surgeons, neurosurgeons, and other clinicians who seek current and reliable information on every aspect of interventional radiology.
Each issue in Journal of Imaging and Interventional Radiology covers critical and cutting-edge medical minimally invasive, clinical, basic research, radiological, pathological, and socioeconomic issues of importance to the field. The journal is a medium for original articles, reviews, pictorial essays, technical notes and case reports related to all fields of interventional radiology.

https://www.imedpub.com/submissions/imaging-interventional-radiology.htmlor an attachment to mail: radiology@emedscholar.com

Best wishes

Ann Jose

Journal coordinator

Journal of Imaging and Interventional Radiology

intervradiology@longdomjournal.org