Radiological Physics and Technology

, Volume 11, Issue 2, pp 212–218 | Cite as

Body size and tube voltage-dependent guiding equations for optimal selection of image acquisition parameters in clinical X-ray imaging

  • Xiaoming Zheng


The purpose of this work was to present body size and tube voltage-dependent equations for optimal selection of image acquisition parameters in guiding clinical X-ray imaging. The dose output of X-ray tubes was expressed as a function of the image acquisition parameters of tube voltage (kVp), tube current–exposure time product (mAs), and body size (d). Dose power (n) to kVp was determined to be a linear function of body size in an earlier phantom study. Tube voltage-dependent attenuation coefficients of water were used to determine the kVp effect on the depth dose of X-rays from the body’s entrance surface. The new expression for the dose output of X-ray tubes in patients was then employed for image quality and radiation dose optimization, assuming that image quality is a logistic function of the radiation dose to patients. For constant kVp, the percentage of mAs increase for a 1-cm increase in body size d is dependent on the kVp applied. For constant mAs, the percentage of kVp increase for a 1-cm increase in body size is dependent on both body size d and the kVp applied. For constant body size, the percentage of kVp increase should be a fraction of the percentage of decrease in the mAs, where the fraction is dependent on the body size. The improved body size and tube voltage-dependent governing equations for variations in X-ray imaging parameters should be more accurate in guiding optimal selection of the kVp and mAs image acquisition parameters in medical X-ray imaging.


X-ray imaging Computed tomography Radiographic imaging Imaging acquisition parameters Guiding equations 



I would like to thank the Journal Editor for English editorial assistance and my colleague Mr. Andrew Kilgour for critical reading of and comments on this manuscript.

Compliance with ethical standards

Conflict of interest

The author declares that there is no conflict of interest in this work.

Research involving human or animal participants

This article does not report any studies involving human participants or animals performed by the author.

Informed consent

Informed consent is not required.


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Copyright information

© Japanese Society of Radiological Technology and Japan Society of Medical Physics 2018

Authors and Affiliations

  1. 1.Medical Radiation Science, School of Dentistry and Health Sciences, Faculty of ScienceCharles Sturt UniversityWagga WaggaAustralia

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