Experimental verification of stopping-power prediction from single- and dual-energy computed tomography in biological tissues

Abstract

Abstract. An experimental setup for consecutive measurement of ion and x-ray absorption in tissue or other materials is introduced. With this setup using a 3D-printed sample container, the reference stopping-power ratio (SPR) of materials can be measured with an uncertainty of below 0.1%. A total of 65 porcine and bovine tissue samples were prepared for measurement, comprising five samples each of 13 tissue types representing about 80% of the total body mass (three different muscle and fatty tissues, liver, kidney, brain, heart, blood, lung and bone). Using a standard stoichiometric calibration for single-energy CT (SECT) as well as a state-ofthe-art dual-energy CT (DECT) approach, SPR was predicted for all tissues and then compared to the measured reference. With the SECT approach, the SPRs of all tissues were predicted with a mean error of (-0.84 ± 0.12)% and a mean absolute error of (1.27 ± 0.12)%. In contrast, the DECT-based SPR predictions were overall consistent with the measured reference with a mean error of (-0.02 ± 0.15)% and a mean absolute error of (0.10 ± 0.15)%. Thus, in this study, the potential of DECT to decrease range uncertainty could be confirmed in biological tissue.

Systematic analysis of the impact of imaging noise on dual‐energy CT‐based proton stopping power ratio estimation

“…If the additional uncertainty due to noise at a 2% noise level for a tumor at 5 cm depth (a worst case scenario) is considered, the total uncertainty becomes 2.52% and 4.10% for the soft and bone tissue group, respectively, which is only a marginal increase of 0.12% and 0.10%. However, a few recent experimental validation studies using DECT reported the overall range uncertainty to be around 1% or less . If 1% were assumed as the range uncertainty for both the soft and bone tissue groups, the total uncertainty after including the noise becomes 1.52% and 1.37% for the soft and bone tissue group, respectively, which is a decent increase of 0.52% and 0.37%.…”

“…Dual‐energy CT (DECT)‐based approaches have demonstrated their capability of reducing this uncertainty as well as their clinical applicability and relevance to the patient . Various methods have been proposed that estimate proton SPR using two or more CT numbers acquired from different energy spectra.…”

“…As a result, the single-energy CT (SECT)-based method has been shown to be sensitive to potential tissue composition variation between different individuals. 4 Dual-energy CT (DECT)-based approaches have demonstrated their capability of reducing this uncertainty [5][6][7][8] as well as their clinical applicability and relevance to the patient. [9][10][11][12][13] Various methods have been proposed that estimate proton SPR using two or more CT numbers acquired from different energy spectra.…”

Reassessment of stopping power ratio uncertainties caused by mean excitation energies using a water‐based formalism

“…Experimental data are under acquisition by our research group and will be disclosed in future publications. However, data on experimental verifications of SPR predictions with DECT have been recently reported . In all three studies, animal tissue samples were used.…”

Theoretical and experimental analysis of photon counting detector CT for proton stopping power prediction

“…These studies include investigations on how to perform a robust calibration of the conversion from CT numbers in conventional single‐energy CT (SECT) to SPR, the influence of beam hardening (BH), the use of dual‐energy CT (DECT), as well as the use of proton CT . It has been shown in several studies that DECT gives more accurate SPR estimates than SECT using the stoichiometric method proposed by Schneider et al …”