Fluence adaptation for contrast-based dose optimization in grating-based X-ray multi-contrast imaging

【作者】 吴承鹏； WANG Zhentian； GAO Hewei； 张丽；

【Author】 WU Chengpeng;WANG Zhentian;GAO Hewei;ZHANG Li;Department of Engineering Physics,Tsinghua University;Key Laboratory of Particle & Radiation Imaging (Tsinghua University) of Ministry of Education;

【机构】 Department of Engineering Physics,Tsinghua University； Key Laboratory of Particle & Radiation Imaging (Tsinghua University) of Ministry of Education； 清华大学工程物理系；

【摘要】 Compared to traditional x-ray imaging,grating-based x-ray imaging（GBXI） can provide additional differential phase-contrast and dark-field images besides the absorption contrast.These complementary contrasts are sensitive to different specific structures such as low-Z soft-tissues and fibrotic lungs,which offers greater potentials in medical applications.In recent few years,GBXI is going from the bench to the bed ^[1-2],but the imaging dose is one of its most important challenges before wide range of clinical applications.The high dose in GBXI is mainly due to the typical phase-stepping process,which requires one of the gratings to move multiple steps under the same x-ray fluence.In another work of our group^[3],we have demonstrated that adopting non-uniform optimized fluence distributions in phase-stepping can be better than using the typical constant one for the multi-order moment analysis.Following similar derivations,in this work,we prove that the fluence adaptation strategy can be extended to the commonly-used Fourier component analysis.Interestingly,the optimal fluence distribution for the differential phasecontrast is almost opposite to that for the dark-filed contrast.Moreover,the optimal one for the absorption contrast is just the typical constant distribution,which can be considered as a comprehensive optimal choice for all three contrasts.To validate our proposed method,we conducted numerical simulations and real experiments,and all results supported that under the same total fluence,the contrast-based optimal fluence distributions can reduce 10%～20% noise variances in both the phase-contrast and dark-filed images,compared to the typical constant one,and vice versa.Combined with^[3],we propose a fluence adaptation mechanism for contrast-based dose optimization in GBXI,which explores a new direction for dose reduction and may also be further extended to other types of x-ray multi-contrast systems such as edge-illumination imaging and analyzer-based imaging.更多还原

【Abstract】 Compared to traditional x-ray imaging,grating-based x-ray imaging（GBXI） can provide additional differential phase-contrast and dark-field images besides the absorption contrast.These complementary contrasts are sensitive to different specific structures such as low-Z soft-tissues and fibrotic lungs,which offers greater potentials in medical applications.In recent few years,GBXI is going from the bench to the bed ^[1-2],but the imaging dose is one of its most important challenges before wide range of clinical applications.The high dose in GBXI is mainly due to the typical phase-stepping process,which requires one of the gratings to move multiple steps under the same x-ray fluence.In another work of our group^[3],we have demonstrated that adopting non-uniform optimized fluence distributions in phase-stepping can be better than using the typical constant one for the multi-order moment analysis.Following similar derivations,in this work,we prove that the fluence adaptation strategy can be extended to the commonly-used Fourier component analysis.Interestingly,the optimal fluence distribution for the differential phasecontrast is almost opposite to that for the dark-filed contrast.Moreover,the optimal one for the absorption contrast is just the typical constant distribution,which can be considered as a comprehensive optimal choice for all three contrasts.To validate our proposed method,we conducted numerical simulations and real experiments,and all results supported that under the same total fluence,the contrast-based optimal fluence distributions can reduce 10%～20% noise variances in both the phase-contrast and dark-filed images,compared to the typical constant one,and vice versa.Combined with^[3],we propose a fluence adaptation mechanism for contrast-based dose optimization in GBXI,which explores a new direction for dose reduction and may also be further extended to other types of x-ray multi-contrast systems such as edge-illumination imaging and analyzer-based imaging.更多还原