Difference Between X-ray and Ultrasound

X-rays, UV rays, IR rays have found many applications in our daily lives. These are dominating the technology world and are used in the working of many instruments. The medical and research field has seen tremendous usage of these waves. Ultrasound waves have also been widely used in medical technology and the case of research. These also harm humans, but given the proper use of the waves, they can be beneficial in certain aspects.

The far-fledged reach of technology and its development have made use of electromagnetic waves and sound waves in several ways to help ease the difficulties of humans. The energy of these waves can be used in various methods or can be converted to some other type of energy for use.

X-ray vs Ultrasound

The main difference between X-rays and Ultrasound is that X-rays are transverse waves and are electromagnetic in nature, while ultrasound waves are categorized as sound waves, which are longitudinal in nature. The x-rays have the capacity to ionize an atom, while the latter does not have any such property.

X ray vs Ultrasound

X-rays are electromagnetic waves having a wavelength ranging from 0.01 nm to 10 nm. These are transverse waves having a frequency ranging from 1016 Hz to 1020 Hz. X-rays have the power to ionize atoms and are used in the treatment of cancer.

Ultrasound waves are sound waves that have a frequency higher than that of 20 kHz. These sound waves are longitudinal in nature and are not audible to the human ear as the human hearing range is 20 Hz- 20 kHz. These longitudinal sound waves require a traveling medium for their propagation.  

Comparison Table Between X-ray and Ultrasound

Parameters of ComparisonX-rayUltrasound
MeaningElectromagnetic waves having a wavelength of 0.01 nm- 10 nm.Sound waves having a frequency greater than 20 kHz.
Frequency1016 Hz – 1020 HzGreater than 20 kHz
Nature of wavesTransverse wavesLongitudinal waves
Ionizing capacityCan ionize atoms and molecules and also penetrates human tissues.Cannot ionize the atoms and molecules.
RisksFound to carry the risk of cancer.Possess no risks.

What is X-ray?

X-rays were discovered by Wilhelm Rontgen. These are electromagnetic waves with a very high frequency, the frequency range being 1016 Hz – 1020 Hz. The X-rays photon consists of some energy which can be calculated by the formula, E= hf (where f is the frequency of photon and h is Plank constantly).

The energy of x-rays ranges from 100 eV – 100 keV. The x-rays can be divided into two categories based on their energy: hard x-rays and soft x-rays. X-rays whose photon energy is above 5keV are hard x-rays. X-rays photons having energy less than 5 keV are known as soft x-rays. Hard x-rays have better penetration capability than soft x-rays.

Due to the penetration capability of the x-rays, they are now used in radiography. These electromagnetic waves can easily penetrate human tissue and hence find use in medical purposes. The most common field employing this is in the treatment of cancer. X-rays have a shorter wavelength compared to other electromagnetic waves, which help in achieving higher resolution. This is made of use in the technique called x-ray crystallography.

X-rays have very high energy, and due to the capability of ionization of atoms and molecules, they can also be a carcinogen. Applications of x-rays: X-ray crystallography, Mammography, CT scan, Airport security system, to check bone fractures, analyzing and checking of paintings, microscopy, and quantitative analysis.

What is Ultrasound?

The normal human hearing range is 20 Hz – 20 kHz. This is called the audible range, while the sounds above this limit are known as ultrasound. Ultrasound waves are sound waves that have a frequency range above 20 kHz. They are mechanical acoustic waves and require a traveling medium. The human ear cannot detect these sounds, but some animals such as dolphins and bats can hear these sounds and also produce them. They use this sound for navigation in pitch dark areas.

Ultrasound has many applications in the medical field, military, communication, navigation is seas, research, and other areas. One of the most widely used ultrasound technology is Ultrasonography, which is a diagnostic technique. The equipment uses Doppler shift and the retiring time of the echoed sound waves for diagnosis purposes.

Usually, piezoelectric crystals are employed for the production of ultrasound. This crystal deforms when an electric potential is applied, the effect being known as the piezoelectric effect. The deformation directly depends upon the amount of potential applied. Some of the applications of ultrasound are: ultrasonic cleaning, crack detection, echocardiography, lithotripsy, ultrasonography, echolocation, and SONAR (Sound Navigation and Ranging technique).

Main Differences Between X-ray and Ultrasound

  1. X-rays are electromagnetic waves while ultrasound wave is categorized as a mechanical acoustic wave.
  2. The frequency range of x-rays is 1016 Hz – 1020 Hz, while the frequency range for ultrasound waves is above 20 kHz.
  3. X-rays can ionize atoms and molecules, while ultrasound cannot.
  4. X-rays have tissue penetration capability, while ultrasound cannot.
  5. X-rays are high energy can cause damage to the human body, while ultrasound is safe to use.
  6. X-ray is found to cause cancer and is a carcinogen, whereas ultrasound does not cause cancer.
Difference Between X ray and Ultrasound


Technology by far has sorted out the use of many things, including electromagnetic waves and sound waves. The X-rays photons and ultrasound waves particles contain photons that have energy. Photons possessing energy can be made of use by converting that energy into a different form or using it in the same form for the detection of substances.

X-rays have a very high frequency and possess high energy. This is one of the reasons that x-rays can penetrate human tissues and can also ionize an atom or a molecule. Ultrasound waves have a frequency range above 20 kHz, which is inaudible to the human ear. Both of them have wide applications, especially in the medical field.


  1. https://link.springer.com/chapter/10.1007/978-1-4899-0148-4_1
  2. https://www.sciencedirect.com/science/article/pii/S0079610706000812
  3. https://www.sciencedirect.com/science/article/pii/B9780126767575500153
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