Potential of dual‐energy subtraction for converting CT numbers to electron density based on a single linear relationship

Saito, Masatoshi

doi:10.1118/1.3694111

Cited by 122 publications

(172 citation statements)

References 17 publications

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“…Finally, the method proposed by Saito [37] to establish a relation between ∆HU and ED theoretically demonstrated an agreement within 0.7% and 2.5% for simulated and measured ED respectively.…”

Section: Introductionmentioning

confidence: 99%

“…At the basis of the stoichiometric calibration of Schneider et al (1996), the parametrization of Jackson and Hawkes [19] relies on Mayneord's power law [26,44] and is limited when it comes to modelling the photoelectric effect in human tissues containing high-Z materials, such as bone [51] or the thyroid [52]. Other problems also arise with the attempt to consistently defining the EAN using a power law, as the choice of the exponent is arbitrary [3,23,37]. One advantage in using an extended cross section parametrization [47,22,27] is to improve the accuracy to which one can model high-Z components.…”

Section: Introductionmentioning

confidence: 99%

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A stoichiometric calibration method for dual energy computed tomography

2014

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A stoichiometric calibration method for dual energy computed tomography

2014

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“…(3) was found to be 3.3 for the diagnostic photon-energy range. 8 This choice of m value is recommended in a previous DECT work by Yang et al 2 On the other hand, the Z m eff and lnI values of the materials are often estimated from their known elemental compositions in an analogous manner of additivity rule as…”

Section: A Derivation Of Spr From Dect Data Via Q E and Z Eff Calimentioning

confidence: 99%

“…7,8 Here, HU k is the CT number in Hounsfield units for high-kV (k = H) and low-kV (k = L) scans, which is related to the so-called "reduced CT number", u k = HU k / 1000 + 1. a is the weighting factor for subtraction and c L is the proportionality constant for the low-energy u L data. These two can be regarded as material-independent but scanner-and protocol-specific fit parameters.…”

Section: A Derivation Of Spr From Dect Data Via Q E and Z Eff Calimentioning

confidence: 99%

Simplified derivation of stopping power ratio in the human body from dual‐energy CT data

Saito

Sagara

2017

Medical Physics

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Purpose: The main objective of this study is to propose an alternative parameterization for the empirical relation between mean excitation energies (I-value) and effective atomic numbers (Z eff ) of human tissues, and to present a simplified formulation (which we called DEEDZ-SPR) for deriving the stopping power ratio (SPR) from dual-energy (DE) CT data via electron density (q e ) and Z eff calibration. Methods: We performed a numerical analysis of this DEEDZ-SPR method for the human-bodyequivalent tissues of ICRU Report 46, as objects of interest with unknown SPR and q e . The attenuation coefficients of these materials were calculated using the XCOM photon cross-sections database. We also applied the DEEDZ-SPR conversion to experimental DECT data available in the literature, which was measured for the tissue-characterization phantom using a dual-source CT scanner at 80 kV and 140 kV/Sn. Results: It was found that the DEEDZ-SPR conversion enables the calculation of SPR simply by means of the weighted subtraction of an electron-density image and a low-or high-kV CT image. The simulated SPRs were in excellent agreement with the reference values over the SPR range from 0.258 (lung) to 3.638 (bone mineral-hydroxyapatite). The relative deviations from the reference SPR were within AE0.6% for all ICRU-46 human tissues, except for the thyroid that presented a À1.1% deviation. The overall root-mean-square error was 0.21%. Application to experimental DECT data confirmed this agreement within the experimental accuracy, which demonstrates the practical feasibility of the method. Conclusions: The DEEDZ-SPR conversion method could facilitate the construction of SPR images as accurately as a recent DECT-based calibration procedure of SPR parameterization based directly on the CT numbers in a DECT data set.

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“…Though PDDs are relatively insensitive to a change in energy spectrum, agreement in the reference and material‐based PDDs provide the clinician confidence that the dose calculation algorithm will accurately compute dose in the material. Methodologies for estimating electron density from CT number have been previously explored 13, 14. Notably, Michiels et al2 reported on the use of dual‐energy CT to estimate the effective atomic number of a 3D‐printed material.…”

Section: Discussionmentioning

confidence: 99%

A framework for clinical commissioning of 3D‐printed patient support or immobilization devices in photon radiotherapy

Meyer

Quirk

D'Souza³

et al. 2018

J Applied Clin Med Phys

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PurposeThe objective of this work is to outline a framework for dosimetric characterization that will comprehensively detail the clinical commissioning steps for 3D‐printed materials applied as patient support or immobilization devices in photon radiotherapy. The complex nature of 3D‐printed materials with application to patient‐specific configurations requires careful consideration. The framework presented is generalizable to any 3D‐printed object where the infill and shell combinations are unknown.MethodsA representative cylinder and wedge were used as test objects to characterize devices that may be printed of unknown, patient‐specific dimensions. A case study of a 3D‐printed CSI immobilization board was presented as an example of an object of known, but adaptable dimensions and proprietary material composition. A series of measurements were performed to characterize the material's kV radiologic properties, MV attenuation measurements and calculations, energy spectrum water equivalency, and surface dose measurements. These measurements complement the recommendations of the AAPM's TG176 to characterize the additional complexity of 3D‐printed materials for use in a clinical radiotherapy environment.ResultsThe dosimetric characterization of 3D‐printed test objects and a case study device informed the development of a step‐by‐step template that can easily be followed by clinicians to accurately and safely utilize 3D‐printed materials as patient‐specific support or immobilization devices.ConclusionsA series of steps is outlined to provide a formulaic approach to clinically commission 3D‐printed materials that may possess varying material composition, infill patterns, and patient‐specific dimensions.

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Potential of dual‐energy subtraction for converting CT numbers to electron density based on a single linear relationship

Cited by 122 publications

References 17 publications

A stoichiometric calibration method for dual energy computed tomography

A stoichiometric calibration method for dual energy computed tomography

Simplified derivation of stopping power ratio in the human body from dual‐energy CT data

A framework for clinical commissioning of 3D‐printed patient support or immobilization devices in photon radiotherapy

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