Review articles

1. Leng et al.  Photon counting detector CT: System design and clinical applications of an emerging technology. Radiographics; 2018
2. Willemink et al. Photon-counting CT: Technical Principles and Clinical Prospects.  Radiology; 2018

System Performance

1. Gutjahr et al. Human imaging with photon counting–based computed tomography at clinical dose levels. Invest Radiol, 2016
   • Evaluates iodine contrast-to-noise ratio as a function of phantom size and tube potential and compares conventional and PCD CT images of human anatomy.
2. Yu et al. Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array.  Phys Med Biol; 2016
   • Describes technology, quantifies the system performance in comparison to conventional CT systems. Includes evaluation of pulse pile-up effects.
3. Yu et al. How low can we go in radiation dose for the data-completion scan on a research whole-body photon-counting computed tomography system? J Comput Assist Tomogr; 2016
   • Describes the purpose of the data completion scan and demonstrates that extremely low doses can be used for this without impacting the quality of PCD CT images.
4. Yu et al. 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.  J Med Imag; 2016
   • Measures the electronic noise of the CounT PCD system and compares it to conventional CT and demonstrates the reduction in electronic noise artifacts with PCD.
5. Li et al. Estimation of signal and noise for a whole-body research photon-counting CT system.  J Med Imag; 2017
   • Describes a methodology for estimating the signal and noise for the CounT PCD system in order to efficiently optimize energy threshold settings.

High Resolution Technology

1. Leng et al. Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system.  J Med Imag; 2016
   • This paper introduces and characterizes the performance of a 250-micron slice thickness acquisition mode. Noise and spatial resolution equivalent to the ultra high resolution mode on a conventional Siemens CT system can be achieved using half the radiation dose. This work was performed using a service mode implementation.
2. Leng et al. 150-μm spatial resolution using photon-counting detector computed tomography technology.  Invest Radiol; 2018
   • Two new PCD acquisition modes – Sharp and UHR – are described and quantitatively characterized. Patient images are provided to demonstrate the potential clinical impact.
3. Pourmorteza et al. Dose efficiency of quarter-millimeter photon-counting computed tomography. Invest Radiol; 2018
   • A .25 mm detector mode on a photon-counting CT system was utilized to image a phantom, animal model, and patients, and found to improve resolution while reducing noise compared to standard resolution.
4. Zhou et al. Lung nodule volume quantification and shape differentiation with an ultra-high resolution technique on a photon-counting detector computed tomography system.  J Med Imag; 2018
   • Anthropomorphic lung nodules are used to demonstrate the improved volume quantification and shape differentiation of the new UHR acquisition mode on the CounT PCD CT system.
5. Symons et al. Quarter-millimeter spectral coronary stent imaging with photon-counting CT: Initial experience. J Cardiac Comput Tomogr; 2018
   • Evaluated the performance and clinical feasibility of 0.25mm resolution mode of a
     DE PCD CT for coronary stent imaging and compared the results to state-of-the-art DE EID CT.

Multi Energy Imaging Performance and Decomposition

1. Leng et al. Spectral performance of a whole-body research photon counting detector CT: Quantitative accuracy in derived image sets.  Phys Med Biol; 2017
   • Using vials of iodine of known concentrations and various sizes of water phantoms, the accuracy of CT numbers in virtual monoenergetic images and iodine concentration in iodine maps were assessed for the Flash, Force and CounT systems.
2. Symons et al. Photon-counting CT for simultaneous imaging of multiple contrast agents in the abdomen: An in vivo study. Med Phys; 2017
   • Iodine, gadolinium, and bismuth were imaged within an animal model using a photon-counting CT system and material decomposition was performed to calculate the concentration of contrast-agents and demonstrate tissue enhancement in multiple phases for a single acquisition.
3. Tao et al. Material decomposition with prior knowledge aware iterative denoising (MD-PKAID).  Phys Med Biol; 2018
   • Image domain material decomposition was performed using a novel iterative denoising algorithm that uses prior information from the low-energy threshold images to reduce errors in material decomposition.

Noise Reduction

1. Harrison et al. A multichannel block-matching denoising algorithm for spectral photon-counting CT images. Med Phys; 2017
   • A denoising algorithm was presented to reduce noise in photon-counting CT images by utilizing the correlation and alignment in different energy bins.
2. Li et al. An effective noise reduction method for multi-energy CT images that exploit spatio-spectral features. Med Phys; 2017
   • A novel multi-energy nonlocal means (MENLM) algorithm is described that uses redundancies in spatio-spectral features to reduce noise by up to 80% while maintaining spatial resolution, shape of the noise-power-spectrum, and CT number accuracy.
3. Rajendran et al. Ultra-high resolution photon-counting detector CT reconstruction using spectral prior image constrained compressed-sensing (UHR-SPICCS).  Proc SPIE Med Imag; 2018
   • A novel iterative reconstruction technique is described and its ability to reduce noise while maintaining ultra-high spatial resolution is demonstrated.

Clinical Applications

1. Pourmorteza et al. Abdominal imaging with contrast-enhanced photon-counting CT: First human experience. Radiology; 2016
2. Pourmorteza et al. Photon-counting CT of the brain: In vivo human results and image-quality assessment. Am J Neuroradiol; 2017
3. Symons et al. Low dose lung cancer screening with photon-counting CT: A feasibility study. Phys Med Biol; 2017
4. Symons et al. Feasibility of dose-reduced chest CT with photon-counting detectors: Initial results in humans. Radiology; 2017
5. Symons et al. Dual-contrast agent photon-counting computed tomography of the heart: Initial experience. Int J Cardiovasc Imaging; 2017
6. Bartlett et al. High-resolution chest CT imaging of the lungs: Impact of 1024 matrix reconstruction and photon-counting-detector CT. Invest Radiol, 2018
7. Ferrero et al. Characterization of urinary stone composition by use of whole-body, photon-counting detector CT.  Acad Radiol; 2018
8. Mannil et al. Photon-counting CT: high-resolution imaging of coronary stents. Invest Radiol; 2018
9. Marcus et al. Detection and classification of renal stones by using photon-counting–based CT.  Radiology; 2018
10. Rajendran et al. Measuring arterial wall perfusion using photon-counting computed tomography (CT): Improving CT number accuracy of artery wall using image deconvolution.  J Med Imag; 2018
11. Symons et al. Photon-counting computed tomography for vascular imaging of the head and neck. Invest Radiol; 2018
12. von Spiczak et al. Photon counting computed tomography with dedicated sharp convolution kernels: Tapping the potential of a new technology for stent imaging. Invest Radiol; 2018
13. Zhou et al. Temporal bone imaging using a photon-counting-detector CT system: A cadaveric study. Am J Neuroradiol; 2018
14. New Symons et al. Coronary artery calcium scoring with photon-counting CT: First in vivo human experience. Int J Cardiovas Imag, 2019

FAQ 1: Can you explain the number of ways that the CounT detector can be used to collect data?

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FAQ 2: How do I know which high-resolution mode to use?

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FAQ 3: What are the differences between the Flash and the CounT?

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FAQ 4: What is the spectral separation for the CounT?

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