X-rays are a form of electromagnetic radiation with unique properties that make them invaluable in a wide range of applications, from medical imaging to industrial testing. Discovered by Wilhelm Roentgen in 1895, X-rays have since become an essential tool in various fields due to their ability to penetrate materials, reveal internal structures, and provide valuable information about the composition and properties of matter. Let's delve into some key X-ray properties and explore their applications in detail.

1. X-Ray Properties
Presenter: Dr. Dheeraj Kumar
MRIT, Ph.D. (Radiology and Imaging)
Assistant Professor
Medical Radiology and Imaging Technology
School of Health Sciences, CSJM University, Kanpur

2. Introduction
 X-rays are a form of electromagnetic radiation with unique properties that
make them invaluable in a wide range of applications, from medical imaging
to industrial testing.
 Discovered by Wilhelm Roentgen in 1895, X-rays have since become an
essential tool in various fields due to their ability to penetrate materials,
reveal internal structures, and provide valuable information about the
composition and properties of matter.
 Let's delve into some key X-ray properties and explore their applications in
detail.
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3. Penetration Power
 X-rays possess high penetration power, allowing them to
pass through most materials, including soft tissues in the
human body.
 This property is crucial in medical imaging, where X-rays
are used to visualize bones and detect fractures, tumors,
and other abnormalities.
 The differential absorption of X-rays by different tissues
creates contrast in X-ray images, enabling radiologists to
identify potential health issues.
 Example: In a chest X-ray, bones, muscles, and organs are
seen as varying shades of gray, while air in the lungs
appears black due to its low X-ray absorption.
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4. Wavelength
 X-rays have much shorter wavelengths compared to visible
light, which enables them to interact with small-scale
structures, including individual atoms and molecules.
 This property is exploited in X-ray crystallography to
determine the atomic arrangement of crystalline
materials.
 X-rays have shorter wavelengths compared to visible light,
typically ranging from 0.01 to 10 nanometers.
 Example: X-ray crystallography has been pivotal in
revealing the structures of DNA, proteins, and other
biomolecules, leading to breakthroughs in the
understanding of life processes.
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5. Frequency
 The ability of X-rays to ionize atoms and molecules
makes them valuable in radiation therapy for
cancer treatment, as well as in industrial
applications for sterilization and disinfection.
 X-rays have a high frequency, ranging from 30
petahertz to 30 exahertz (30 × 10
15
to 30 × 10
18
hertz) and energies in the range of 100 eV to 100
keV.
 Example: In radiation therapy, high-energy X-rays
are directed at cancerous tissues to damage their
DNA and inhibit their growth.
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6. Traveling Speed
 X-rays travel at the speed of light in a vacuum,
allowing for real-time imaging in medical
applications, such as fluoroscopy. Fluoroscopy is used
to guide procedures like catheter placements and
joint injections.
 Traveling Speed: X-rays travel at the speed of light in
a vacuum, which is approximately 299,792 kilometers
per second (186,282 miles per second)/ 3ⵝ108
Meters/second.
 Example: During a fluoroscopy-guided procedure, the
doctor can watch the movement of the contrast dye
or medical instrument in real-time on a monitor.
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7. Electrically Neutral
 X-rays are electrically neutral, meaning they
carry no net electrical charge. This property
enables them to interact with matter without
being significantly influenced by electric fields.
 X-rays can pass through materials without being
deflected, enabling the production of sharp and
detailed images.
 Example: When X-rays pass through a metallic
object, such as a coin, their path remains
unaffected, and an X-ray detector on the other
side can capture the image of the coin.
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8. Absorption
 X-rays are absorbed by materials to different
degrees based on their density and atomic
number.
 Dense materials, like bones and metals, absorb
more X-rays, while less dense materials, like soft
tissues, allow X-rays to pass through more easily.
 This property is essential in medical and
industrial imaging to create contrast and reveal
internal structures.
 Example: In a dental X-ray, the enamel and
dentin in the teeth absorb X-rays, while the
surrounding gums and air spaces allow X-rays to
pass through.
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9. Reflection
 X-rays can undergo reflection when they
encounter a smooth and reflective surface,
similar to visible light.
 However, reflection of X-rays is less common in
practical applications compared to other
electromagnetic waves.
 Example: X-ray mirrors, although challenging to
produce, have been used in some research
facilities to focus X-rays for specific experiments.
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10. Refraction
 X-rays can refract or change direction when
they pass from one medium to another with a
different refractive index.
 This property is not as prominently utilized as
it is in visible light due to the high penetration
power of X-rays.
 Example: Scientists have used X-ray refraction
techniques to study specific materials, but it is
not as widespread as other X-ray applications.
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11. Scattering
 X-rays can scatter in various directions when
they interact with atoms and electrons in a
material.
 Compton scattering is one such phenomenon
used in X-ray diffraction studies to determine the
structure of materials.
 Example: In X-ray diffraction studies,
researchers analyse the scattered X-rays to
reveal the arrangement of atoms in a crystal
lattice.
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12. Fluorescence
 When X-rays strike certain materials, they can
cause the emission of lower-energy photons in a
process known as X-ray fluorescence.
 This phenomenon is utilized in material analysis
and elemental identification.
 Example: In X-ray fluorescence spectroscopy, a
sample is exposed to X-rays, and the emitted
characteristic X-rays from the sample are
analyzed to identify its elemental composition.
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13. Ionization
 X-rays have sufficient energy to ionize atoms
by knocking electrons from their orbitals,
leading to the creation of charged particles.
 This property is harnessed in radiation therapy
for cancer treatment and is also used to study
the interaction of X-rays with matter.
 Example: X-rays used in radiation therapy can
create ions in cancer cells, leading to cell
death and tumour shrinkage.
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14. Attenuation
 X-rays experience attenuation as they pass
through matter due to absorption and
scattering.
 The degree of attenuation is used to calculate
the thickness or density of the material being
imaged, as seen in computed tomography (CT)
scans.
 Example: In a CT scan, the X-ray beam is
rotated around the patient's body, and the
attenuation data is processed by a computer
to create detailed cross-sectional images.
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15. Polarization
 X-rays can be polarized, meaning the oscillations of their
electric field occur in a specific direction.
 Polarized X-rays are used in certain diffraction
experiments to study the orientation of molecules in a
material.
 Example: Polarized X-ray diffraction is used to
investigate the molecular alignment and ordering in
liquid crystals.
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16. Coherence
 X-rays can exhibit coherence, where the phase
relationships between their waves are
maintained over a certain distance.
 This coherence is crucial in X-ray crystallography
for obtaining high-resolution structural
information.
 Example: Coherent X-ray diffraction is employed
to study the structure of nanoscale materials
with atomic precision.
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17. Doppler Effect
 When X-rays interact with moving
particles, they can experience a
Doppler shift in their frequency,
which is useful in X-ray astronomy to
study celestial bodies' motions.
 Example: X-ray observations of binary
star systems can provide information
about the velocity and orbital motion
of stars.
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18. Dual-energy Imaging
 X-rays can be produced at two different
energy levels simultaneously, allowing for
improved tissue differentiation in medical
imaging, such as identifying calcifications
or iodine contrast in blood vessels.
 Example: Dual-energy X-ray
absorptiometry (DEXA) is used to measure
bone mineral density and assess the risk of
osteoporosis.
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19. Polychromatic vs. Monochromatic
 X-rays can be polychromatic, containing a range of
energies, or monochromatic, with a single energy
level.
 Monochromatic X-rays are utilized in certain
research applications to enhance the precision of
measurements.
 Example: Monochromatic X-rays are employed in X-
ray crystallography to reduce background noise and
improve data quality.
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20. X-ray Absorption Near Edge Structure
(XANES)
 This property is used in X-ray spectroscopy to
study the electronic structure and chemical
state of atoms in a material.
 Example: XANES is used to study the oxidation
state of transition metals in catalysts to
optimize their efficiency in chemical reactions.
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21. X-ray Diffraction (XRD)
 X-rays can diffract when they interact with
a crystalline material, producing a
diffraction pattern that reveals the atomic
arrangement.
 XRD is an essential technique in materials
science.
 Example: XRD is used to identify the
crystalline phases present in a material,
helping to determine its structure and
properties.
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22. Photoelectric Effect
 X-rays can cause the photoelectric effect,
where an incident X-ray photon is absorbed,
and an electron is ejected from an atom.
 This phenomenon is applied in X-ray
detectors, such as those used in X-ray
imaging systems.
 Example: Photoelectric detectors in X-ray
machines capture the transmitted X-rays to
produce images of the internal structures of
the human body.
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23. Non-destructive Testing (NDT)
 X-rays are widely used in industrial
applications for non-destructive testing
of materials, welds, and components.
 NDT allows manufacturers to inspect
critical parts without damaging or
destroying them.
 Example: In the aerospace industry, X-
ray inspection is used to check the
integrity of aircraft components,
ensuring they meet safety standards.
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24. Baggage and Cargo Scanning and
Security Screening
 X-ray scanners are employed at airports and border
checkpoints to examine the contents of baggage and
cargo for prohibited or dangerous items.
 X-ray systems are employed in security screening at
public venues, ensuring safety by detecting concealed
weapons and other threats.
 Examples
 X-ray scanners at airports help security personnel
identify potential threats concealed within luggage.
 X-ray scanners at entrances to public events help
prevent potential security breaches.
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25. X-ray Astronomy
 X-rays are used in astronomy to study high-
energy phenomena in space, such as black
holes, neutron stars, and supernovae.
 Example: X-ray telescopes like Chandra X-
ray Observatory provide essential data for
understanding the extreme physics of
celestial objects.
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26. X-ray Fluoroscopy
 Fluoroscopy is a real-time X-ray imaging
technique used in medical procedures, such as
cardiac catheterization and barium swallow
examinations.
 Example: During a cardiac catheterization
procedure, a catheter is guided through blood
vessels using fluoroscopy to diagnose and treat
heart conditions.
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27. Biological Effect
 These effects are primarily due to the ionizing nature of X-rays, which means they
have enough energy to remove tightly bound electrons from atoms and molecules,
leading to the creation of charged particles (ions).
 Here are some biological effects of X-rays on living organisms, along with
Examples: DNA damage caused by X-ray exposure can result in mutations,
chromosomal aberrations, and potentially lead to the development of cancer over
time.
 High doses of X-ray radiation used in cancer therapy can kill cancer cells by
inducing widespread damage to their DNA and cellular components.
 Acute radiation sickness can occur in individuals exposed to high levels of X-rays
during nuclear accidents or incidents involving high-energy sources.
 Radiologists and healthcare workers who are exposed to X-rays regularly may have
a slightly higher risk of developing cancer due to cumulative radiation exposure.
 Radiation-induced skin damage, called radiation dermatitis, is a common side
effect in cancer patients undergoing radiation therapy.
 Radiologists and technicians who do not wear appropriate protective gear may be
at risk of developing cataracts due to long-term exposure to X-rays.
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28. Summary
 X-rays are a powerful form of electromagnetic radiation with diverse
properties that have revolutionized various fields.
 From medical diagnostics and therapy to materials science and industrial
applications, X-rays have proven indispensable in modern technology and
scientific research.
 Their ability to penetrate matter, interact with atoms, and produce detailed
images make them invaluable tools in advancing our understanding of the
world around us and improving the quality of life for millions.
 However, it is essential to use X-rays responsibly and judiciously to minimize
potential risks associated with ionizing radiation.
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29. References
 "Radiology Basics - X-ray Properties." Radiology Cafe. Website: https://radiologycafe.com/radiology-
trainees/basic-principles/x-ray-properties
 "Physics of X-rays." Radiopaedia. Website: https://radiopaedia.org/articles/physics-of-x-rays?lang=us
 Bushberg, J. T., Seibert, J. A., Leidholdt, E. M., & Boone, J. M. (Eds.). (2017). "The Essential Physics
of Medical Imaging" (3rd ed.). Lippincott Williams & Wilkins.
 Huda, W. (2016). "Review of Radiologic Physics" (4th ed.). Wolters Kluwer.
 Thibodeau, G. A., & Patton, K. T. (2017). "Anatomy & Physiology" (10th ed.). Elsevier.
 National Council on Radiation Protection and Measurements. (2009). Ionizing Radiation Exposure of
the Population of the United States. NCRP Report No. 160.
 United Nations Scientific Committee on the Effects of Atomic Radiation. (2000). Sources and Effects of
Ionizing Radiation: UNSCEAR 2000 Report to the General Assembly, with Scientific Annexes. Volume I:
Sources. United Nations.
 National Research Council. (2006). Health Risks from Exposure to Low Levels of Ionizing Radiation:
BEIR VII Phase 2. The National Academies Press.
 Health Physics Society. (2021). Radiation Exposure and Pregnancy: A Fact Sheet for Clinicians. Health
Physics Society.
 International Atomic Energy Agency. (2011). Biological Effects of Ionizing Radiation: Annex B. IAEA
Safety Standards Series No. RS-G-1.1.
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