Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers
<strong><em>Introduction:</em></strong> In dual-energy computed tomography (DECT), the Hounsfield values of a substance measured at two different energies are the basic data for finding the chemical properties of a substance. The trends of Hounsfield unit (HU) alterations fol...
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| Format: | Article |
| Language: | English |
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Mashhad University of Medical Sciences
2020-09-01
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| Series: | Iranian Journal of Medical Physics |
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| Online Access: | http://ijmp.mums.ac.ir/article_14340_92df18cba983745d30cd5952c2720ba3.pdf |
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| author | Fariba Zarei Sabysachi chatterjee Vani Vardhan Chatterjee Rezvan Ravanfar Haghighi |
| author_facet | Fariba Zarei Sabysachi chatterjee Vani Vardhan Chatterjee Rezvan Ravanfar Haghighi |
| author_sort | Fariba Zarei |
| collection | DOAJ |
| description | <strong><em>Introduction:</em></strong> In dual-energy computed tomography (DECT), the Hounsfield values of a substance measured at two different energies are the basic data for finding the chemical properties of a substance. The trends of Hounsfield unit (HU) alterations following the changes in energy are different between the materials with high and low Z<sub>eff</sub>. The present study aimed to analyze the basic principles related to the attenuation coefficient of x-ray photons and a quantitative explanation is given for the mentioned behavior or trend.
<strong><em>Material and Methods:</em></strong> A mathematical expression was derived for the HU difference between two different scanner voltages. Attenuation coefficients of diverse substances, such as methanol, glycerol, acetic acid, the aqueous solution of potassium hydroxide, and water were calculated for x-ray scanners operating differently at distinct applied voltages and with diverse inherent or added filters.
<strong><em>Results:</em></strong> Findings of the current study demonstrated that the negative or positive outcome of HU(V<sub>1</sub>) - HU(V<sub>2</sub>) equation is not determined by the electron density of a substance. However, it is affected by the effective atomic number <em>(Z<sub>eff</sub>)</em> of the material and machine parameters specified by the source spectrum.
<strong><em>Conclusion: </em></strong>According to our results, the sign of HU difference [HU(V<sub>1</sub>) – HU(V<sub>2</sub>)] for the variable cases of V<sub>2</sub> and V<sub>1</sub> gives an indication of the effective atomic number of the material under study. The obtained results might be of diagnostic value in the DECT technique. |
| first_indexed | 2024-12-14T22:56:04Z |
| format | Article |
| id | doaj.art-42c20f5181a04027b38c7ad02816aa1b |
| institution | Directory Open Access Journal |
| issn | 2345-3672 2345-3672 |
| language | English |
| last_indexed | 2024-12-14T22:56:04Z |
| publishDate | 2020-09-01 |
| publisher | Mashhad University of Medical Sciences |
| record_format | Article |
| series | Iranian Journal of Medical Physics |
| spelling | doaj.art-42c20f5181a04027b38c7ad02816aa1b2022-12-21T22:44:34ZengMashhad University of Medical SciencesIranian Journal of Medical Physics2345-36722345-36722020-09-0117534034910.22038/ijmp.2019.42841.164214340Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic NumbersFariba Zarei0Sabysachi chatterjee1Vani Vardhan Chatterjee2Rezvan Ravanfar Haghighi3Medical imaging research center, Shiraz university of medical sciences, Shiraz, IranOngil, 79 D3, Sivaya Nagar, Reddiyur Alagapuram, Salem 636004. IndiaDepartment of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012. INDIAMedical Imaging Research Center, Shiraz University of Medical Sciences, Shiraz, Iran<strong><em>Introduction:</em></strong> In dual-energy computed tomography (DECT), the Hounsfield values of a substance measured at two different energies are the basic data for finding the chemical properties of a substance. The trends of Hounsfield unit (HU) alterations following the changes in energy are different between the materials with high and low Z<sub>eff</sub>. The present study aimed to analyze the basic principles related to the attenuation coefficient of x-ray photons and a quantitative explanation is given for the mentioned behavior or trend. <strong><em>Material and Methods:</em></strong> A mathematical expression was derived for the HU difference between two different scanner voltages. Attenuation coefficients of diverse substances, such as methanol, glycerol, acetic acid, the aqueous solution of potassium hydroxide, and water were calculated for x-ray scanners operating differently at distinct applied voltages and with diverse inherent or added filters. <strong><em>Results:</em></strong> Findings of the current study demonstrated that the negative or positive outcome of HU(V<sub>1</sub>) - HU(V<sub>2</sub>) equation is not determined by the electron density of a substance. However, it is affected by the effective atomic number <em>(Z<sub>eff</sub>)</em> of the material and machine parameters specified by the source spectrum. <strong><em>Conclusion: </em></strong>According to our results, the sign of HU difference [HU(V<sub>1</sub>) – HU(V<sub>2</sub>)] for the variable cases of V<sub>2</sub> and V<sub>1</sub> gives an indication of the effective atomic number of the material under study. The obtained results might be of diagnostic value in the DECT technique.http://ijmp.mums.ac.ir/article_14340_92df18cba983745d30cd5952c2720ba3.pdfatomic number dualenergy computed tomography effective energy hounsfield unit |
| spellingShingle | Fariba Zarei Sabysachi chatterjee Vani Vardhan Chatterjee Rezvan Ravanfar Haghighi Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers Iranian Journal of Medical Physics atomic number dual energy computed tomography effective energy hounsfield unit |
| title | Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers |
| title_full | Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers |
| title_fullStr | Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers |
| title_full_unstemmed | Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers |
| title_short | Reversal Trend of Hounsfield Unit Values of Substances with High and Low Effective Atomic Numbers |
| title_sort | reversal trend of hounsfield unit values of substances with high and low effective atomic numbers |
| topic | atomic number dual energy computed tomography effective energy hounsfield unit |
| url | http://ijmp.mums.ac.ir/article_14340_92df18cba983745d30cd5952c2720ba3.pdf |
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