<p>Flat-panel X-ray sources (FPXSs) have many advantages in terms of compactness and low-dose imaging, enhancing their capability for novel X-ray applications. Experimental analysis of the X-ray characteristics and optimizing the anode panel of an FPXS are time-consuming, expensive, and sometimes impractical. In this study, a FPXS was prepared using a ZnO nanowire cold cathode and a molybdenum film anode target. Monte Carlo (MC) simulations were utilized to optimize the anode panel and obtain the average fluence, average energy, and spatial distribution of the X-rays for the ZnO nanowire FPXS. The accuracy of the MC simulations was verified by comparing the measured and simulated energy spectra. Optimization of the anode target considers the material, thickness, and morphology, whereas optimization of the substrate focuses on the material and thickness. The results show that the difference between the positions of the K-shell peaks in the measured and simulated energy spectra is within 0.26 keV. At the acceleration voltages of 30 kV, 60 kV, and 90 kV, the optimal thicknesses of the tungsten array anode were 0.65 <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">$\upmu$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">μ</mi> </math></EquationSource> </InlineEquation>m, 2.45 <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">$\upmu$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">μ</mi> </math></EquationSource> </InlineEquation>m, and 5 <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">$\upmu$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">μ</mi> </math></EquationSource> </InlineEquation>m, respectively, while the molybdenum array anode has the optimal thicknesses of 1.45 <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">$\upmu$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">μ</mi> </math></EquationSource> </InlineEquation>m, 5.25 <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">$\upmu$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">μ</mi> </math></EquationSource> </InlineEquation>m, and 24 <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq1.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="12" /> </InlineMediaObject> <EquationSource Format="TEX">$\upmu$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">μ</mi> </math></EquationSource> </InlineEquation>m, respectively. The microsemi-ellipsoidal anode with a recessed design showed a 5<InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1765_Article_IEq7.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">$\%$</EquationSource> <EquationSource Format="MATHML"><math> <mo>%</mo> </math></EquationSource> </InlineEquation> increase in the transmitted X-ray fluence compared with the film target. The sapphire substrate with a thickness of 0.78 mm exhibits a mechanical strength comparable to that of a glass substrate with a thickness of 3 mm, implying that the former can increase the average X-ray fluence by reducing the filtration of X-rays. The findings of this study provide valuable guidance for the fabrication and optimization of the ZnO nanowire FPXS.</p>

Characteristic analysis of anode panel for a ZnO nanowire cold cathode flat-panel X-ray source using Monte Carlo simulations

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发表日期：

2025年7月19日

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Xiao-Ying Zhang,
Jian-Cong Dai,
Jun Chen,
Wang-Jiang Wu,
Yuan Xu

摘要

Flat-panel X-ray sources (FPXSs) have many advantages in terms of compactness and low-dose imaging, enhancing their capability for novel X-ray applications. Experimental analysis of the X-ray characteristics and optimizing the anode panel of an FPXS are time-consuming, expensive, and sometimes impractical. In this study, a FPXS was prepared using a ZnO nanowire cold cathode and a molybdenum film anode target. Monte Carlo (MC) simulations were utilized to optimize the anode panel and obtain the average fluence, average energy, and spatial distribution of the X-rays for the ZnO nanowire FPXS. The accuracy of the MC simulations was verified by comparing the measured and simulated energy spectra. Optimization of the anode target considers the material, thickness, and morphology, whereas optimization of the substrate focuses on the material and thickness. The results show that the difference between the positions of the K-shell peaks in the measured and simulated energy spectra is within 0.26 keV. At the acceleration voltages of 30 kV, 60 kV, and 90 kV, the optimal thicknesses of the tungsten array anode were 0.65 $\upmu$ $μ$ m, 2.45 $\upmu$ $μ$ m, and 5 $\upmu$ $μ$ m, respectively, while the molybdenum array anode has the optimal thicknesses of 1.45 $\upmu$ $μ$ m, 5.25 $\upmu$ $μ$ m, and 24 $\upmu$ $μ$ m, respectively. The microsemi-ellipsoidal anode with a recessed design showed a 5 $\%$ $%$ increase in the transmitted X-ray fluence compared with the film target. The sapphire substrate with a thickness of 0.78 mm exhibits a mechanical strength comparable to that of a glass substrate with a thickness of 3 mm, implying that the former can increase the average X-ray fluence by reducing the filtration of X-rays. The findings of this study provide valuable guidance for the fabrication and optimization of the ZnO nanowire FPXS.