Noise performance of low-dose CT: comparison between an energy integrating detector and a photon counting detector using a whole-body research photon counting CT scanner

Yu, Zhicong; Leng, Shuai; Kappler, S.; Hähn, Katharina; Li, Zhoubo; Halaweish, Ahmed F.; Henning, André; McCollough, Cynthia H.

doi:10.1117/1.jmi.3.4.043503

Cited by 86 publications

(68 citation statements)

References 11 publications

(21 reference statements)

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“…Several studies have shown that the PCD‐CT have various advantages compared to the conventional EID‐CT, including improved iodine contrast, reduced electronic noise, more stable CT number in low dose realm, and dose‐efficient high‐resolution capability . The DS‐PCD system is expected to preserve these advantages as it is equipped with the same core PCD technology.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have shown that the PCD-CT have various advantages compared to the conventional EID-CT, including improved iodine contrast, reduced electronic noise, more stable CT number in low dose realm, and dose-efficient highresolution capability. [6][7][8][9][10] The DS-PCD system is expected to preserve these advantages as it is equipped with the same core PCD technology. These advantages can potentially be used to improve image quality under the same radiation dose, or to reduce patient dose while maintain the same image quality such as resolution and noise level.…”

Section: Discussionmentioning

confidence: 99%

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Feasibility of multi‐contrast imaging on dual‐source photon counting detector (PCD) CT: An initial phantom study

et al. 2019

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Purpose Photon‐counting‐detector‐computed tomography (PCD‐CT) allows separation of multiple, simultaneously imaged contrast agents, such as iodine (I), gadolinium (Gd), and bismuth (Bi). However, PCDs suffer from several technical limitations such as charge sharing, K‐edge escape, and pulse pile‐up, which compromise spectral separation of multi‐energy data and degrade multi‐contrast imaging performance. The purpose of this work was to determine the performance of a dual‐source (DS) PCD‐CT relative to a single‐source (SS) PCD‐CT for the separation of simultaneously imaged I, Gd, and Bi contrast agents. Methods Phantom experiments were performed using a research whole‐body PCD‐CT and head/abdomen‐sized phantoms containing vials of different I, Gd, Bi concentrations. To emulate a DS‐PCD‐CT, the phantoms were scanned twice on the SS‐PCD‐CT using different tube potentials for each scan. A tube potential of 80 kV (energy thresholds = 25/50 keV) was used for low‐energy tube, while the high‐energy tube used Sn140 kV (Sn indicates tin filter) and thresholds of 25/90 keV. The same phantoms were scanned also on the SS‐PCD‐CT using the chess acquisition mode. In chess mode, the 4 × 4 subpixels within a macro detector pixel are split into two sets based on a chess‐board pattern. With each subpixel set having two energy thresholds, chess mode allows four energy‐bin data sets, which permits simultaneous multi‐contrast imaging. Because of this design, only 50% area of each detector pixel is configured to receive photons of a pre‐defined threshold, leading to 50% dose utilization efficiency. To compensate for this dose inefficiency, the radiation dose for this scan was doubled compared to DS‐PCD‐CT. A 140 kV tube potential and thresholds = 25/50/75/90 keV were used. These settings were determined based on the K‐edges of Gd, and Bi, and were found to yield good differentiation of I/Gd/Bi based on phantom experiments and other literature. The energy‐bin images obtained from each scan (scan pair) were used to generate I‐, Gd‐, Bi‐specific image via material decomposition. Root‐mean‐square‐error (RMSE) between the known and measured concentrations was calculated for each scenario. A 20‐cm water cylinder phantom was scanned on both systems, which was used for evaluating the magnitude of noise, and noise power spectra (NPS) of I/Gd/Bi‐specific images. Results Phantom results showed that DS‐PCD‐CT reduced noise in material‐specific images for both head and body phantoms compared to SS‐PCD‐CT. The noise level of SS‐PCD was reduced from 2.55 to 0.90 mg/mL (I), 1.97 to 0.78 mg/mL (Gd), and 0.85 to 0.74 mg/mL (Bi) using DS‐PCD. NPS analysis showed that the noise texture of images acquired on both systems is similar. For the body phantom, the RMSE for SS‐PCD‐CT was reduced relative to DS‐PCD‐CT from 10.52 to 2.76 mg/mL (I), 7.90 to 2.01 mg/mL (Gd), and 1.91 to 1.16 mg/mL (Bi). A similar trend was observed for the head phantom: RMSE reduced from 2.59 (SS‐PCD) to 0.72 (DS‐PCD) mg/mL (I), 2.02 to 0.58 mg/mL (Gd), and 0.85 to 0.57 mg/mL (Bi). Co...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Feasibility of multi‐contrast imaging on dual‐source photon counting detector (PCD) CT: An initial phantom study

et al. 2019

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“…PCDs measure individual photons and their associated energy, rather than the integrated charges generated by all measured photons, as occurs with an energy-integrating detector (EID). This provides unique benefits compared to EIDs, including lower electronic noise, higher contrast to noise ratio (CNR) and improved dose efficiency, as demonstrated in recent studies (Schmidt, 2010, Gutjahr et al, 2016, Yu et al, 2016b). In addition, the energy discrimination nature of the PCD enables a simultaneous multi-energy imaging technique using a single tube, single tube potential (kV), and single detector (Roessl and Proksa, 2007, Schlomka et al, 2008, Kappler et al, 2014, Li et al, 2015, Faby et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Spectral performance of a whole-body research photon counting detector CT: quantitative accuracy in derived image sets

et al. 2017

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Photon-counting computed tomography (PCCT) uses a photon counting detector to count individual photons and allocate them to specific energy bins by comparing photon energy to preset thresholds. This enables simultaneous multi-energy CT with a single source and detector. Phantom studies were performed to assess the spectral performance of a research PCCT scanner by assessing the accuracy of derived images sets. Specifically, we assessed the accuracy of iodine quantification in iodine map images and of CT number accuracy in virtual monoenergetic images (VMI). Vials containing iodine with 5 known concentrations were scanned on the PCCT scanner after being placed in phantoms representing the attenuation of different size patients. For comparison, the same vials and phantoms were also scanned on 2nd and 3rd generation dual-source, dual-energy (DSDE) scanners. After material decomposition, iodine maps were generated, from which iodine concentration was measured for each vial and phantom size and compared with the known concentration. Additionally, VMIs were generated and CT number accuracy was compared to the reference standard, which was calculated based on known iodine concentration and attenuation coefficients at each keV obtained from the U.S. National Institute of Standards and Technology. Results showed accurate iodine quantification (root mean square error of 0.5 mgI/cc) and accurate CT number of VMIs (percentage error of 8.9%) using the PCCT scanner. The overall performance of the PCCT scanner, in terms of iodine quantification and VMI CT number accuracy, was comparable to that of EID-based dual-source, dual-energy scanners.

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“…CdTe is a II-VI compound semiconductor material, with attractive properties for a number of energy 1 and imaging applications. 2 These properties include a direct bandgap in the infrared region (1.5 eV), and a relatively high density of 5.85 g/cm 3 (which confers enhanced stopping power for high energy radiation).…”

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confidence: 99%

“…2 At present, CdTe is being intensively researched as a direct detector material for tomographic medical imaging, 3 but to date it has not seen mainstream application. 2 Growth of CdTe single crystals is a difficult and expensive process, and present devices are affected by relatively high defect densities and performance instability.…”

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Determination of the mean inner potential of cadmium telluride via electron holography

Cassidy

Dhar

Shintake

2017

Applied Physics Letters

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Mean inner potential is a fundamental material parameter in solid state physics and electron microscopy and has been experimentally measured in CdTe, a technologically important semiconductor. As a first step, the inelastic mean free path for electron scattering in CdTe was determined, using electron energy loss spectroscopy, to enable precise thickness mapping of thin CdTe lamellae. The obtained value was λi(CdTe, 300 kV) = 192 ± 10 nm. This value is relatively large, given the high density of the material, and is discussed in the text. Next, electron diffraction and specimen tilting were employed to identify weakly diffracting lattice orientations, to enable the straightforward measurement of the electron phase shift. Finally, electron holography was utilized to quantitatively map the phase shift experienced by electron waves passing through a CdTe crystal, with several different propagation vectors. Utilization of both thickness and phase data allowed computation of mean inner potential as V0 (CdTe) = 14.0 ± 0.9 V, within the range of previous theoretical estimates.

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Noise performance of low-dose CT: comparison between an energy integrating detector and a photon counting detector using a whole-body research photon counting CT scanner

Cited by 86 publications

References 11 publications

Feasibility of multi‐contrast imaging on dual‐source photon counting detector (PCD) CT: An initial phantom study

Feasibility of multi‐contrast imaging on dual‐source photon counting detector (PCD) CT: An initial phantom study

Spectral performance of a whole-body research photon counting detector CT: quantitative accuracy in derived image sets

Determination of the mean inner potential of cadmium telluride via electron holography

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