We appreciate voluntary contribution of Scott Hsieh, Ph.D. of UCLA. Scott has tested a few ideas to speed up script_workflow_PcTK.m and his suggestion is now implemented in version 1.03. The new code improved the computation of correlated noisy data from 7–12 s/proj to 6–7 s/proj depending on CPUs and memory sizes. The new release will be sent to all of licensees soon and included in PcTK package 3.22a.

Thank you Scott for your help!

Today we have issued the 31st license! The licenses have been issued to academic researchers all over the world, from USA (14 licenses), China (5), South Korea (4), Germany (2), Taiwan (1), France (1), Canada (1), Baku Azerbaijan (1), and Pakistan (1). We are sorry that we had to turn down several other requests from industry researchers. But we are very pleased that our work is directly helping other groups research activities and looking forward to seeing their presentation and papers somewhere. It would be great if you keep us posted with your progress, once it is published.

We have had more than 1,500 views and the average time on page is more than 2 minutes, which means visitors are actually reading the pages, not bouncing off quickly. This map may reflect a distribution of photon counting CT researchers in the world, although we had expected more visitors from Europe, considering their activities. Probably we should find a way to advertise PcTK in Europe.

 

Congrats to Ken Taguchi and co-authors on the acceptance of his journal paper entitled “Spatio-energetic cross-talk in photon counting detectors: NxN binning and sub-pixel masking.” The paper has been published in the Medical Physics online.

This paper is the first that uses Photon Counting Toolkit (PcTK) and analyzes the effect of pixel-binning and pixel-masking (or anti-scatter grids) on charge sharing and cross-talks of photon counting CT. We think that this paper demonstrates a potential of our PcTK and shows an example of how you can use PcTK to analyze/assess properties-of-your-interest.

Let us know if you publish a paper in journal or at a conference that uses PcTK. We will be honored to add to an archive.

 

We were honored to be invited to present our views and perspectives on spectral photon counting CT at the 2018 annual meeting of AAPM in Nashville, Tennessee. It was an excellent symposium (WE-HI-202) organized by Shuai Leng, Ph.D. of Mayo Clinic. Videos might become available online later.

August 1, 2018. 1:45–3:45 pm, Room 202

Multi-energy and multi-contrast CT imaging. SAM imaging scientific symposium

• “Multi-energy/dual-energy CT technology, clinical applications, and future directions,” D. Sahani
• “Multi-energy CT using energy integrating detectors,” L. Yu
• “Multi-energy CT using photon counting detectors,” K. Taguchi 
• “Novel contrast agents for multi-energy CT imaging,” D. Cormode

script_workflow_PcTK_NoCorrelation.m has been updated to version 1.1. The new file can be downloaded from here and will be included in the package version 3.22.

There was a mistake on how to use a Matlab function normrnd(mu, sigma). The ‘sigma’ must be the standard deviation of data, sqrt(m2_yt), not the variance of data, m2_yt. The corrected code in lines 260–268 in version 1.1 appears:

•             %   Step 5. Generate a noisy 4-D count sinogram, nRm(Nl,ch,row,view)
•             switch iflag_noise
•                 case flag_noise_normal  % gen Gaussian data
•                     m2_yn = normrnd(m2_yt, sqrt(m2_yt));        % ver 1.1
•                 case flag_noise_Poisson % gen Poisson data
•                     m2_yn = random(‘Poisson’, m2_yt);
•             end
•             m3_yt(:,:,irow) = m2_yt;
•             m3_yn(:,:,irow) = m2_yn;

We thank Danyang Li of The Southern Medical University for drawing our attention to it.

A frequently asked questions and answers (FAQs) page has been provided and will be updated frequently.

Our PcTK site is now at the No. 1 ranking of Google search with “Photon counting toolkit”.

1) A few students have asked us how to set up parameters for their simulations; and most of these questions was related not to PCDs but to their CT systems and objects. While we wish to help as many as possible, we have limited time and resources, and thus, wish to focus on the fundamental part of PcTK such as gen_nCovE.m and calc_nCovE_3x3pix.p. We ask junior students to consult with senior students, postdocs, and professors for the guidance.

 

2) We have updated notes in the two wrappers, “script_workflow_PcTK.m” and “script_workflow_PcTK_NoCorrelation.m”

(a) A correction to Note 1 on how to calculate N0, the parameter for the number of photons per projection per PCD pixel, without attenuation. We thank Lisha Yao of Southern Medical University (China) for drawing our attention to it.

• Note 1: One tube gives ~2.2*10^6 counts/(s*mA*mm^2) at 1 m away with 120 kVp (Ref. 3)
•         N0 = 2.2*10^6*tc/(nprojpersec)*(dpix/1000)^2.*(1000/Rd)^2
•            = 14,322.9 photons/projection/pixel through the air
•             tc          : tube current (mA), 600
•             nprojpersec : # of projections (/s), 4000
•             dpix        : PCD pixel size (um), 225
•             Rd          : Focus-to-PCD distance (mm), 1080

(b) The information on Ref. 3. J. Cammin, J. Xu, W.C. Barber, J.S. Iwanczyk, N.E. Hartsough, and K. Taguchi, “A cascaded model of spectral distortion due to spectral response effect and pulse pileup effects in a photon-counting x-ray detector for CT,” Medical Physics, Vol. 41(4), 041905 (2014); doi: 10.1118/1.4866890.

(c) A note on the official website (pctk.jhu.edu) and “Who is us” added.

Congrats to Ken Taguchi on the acceptance of his journal paper on PcTK version 3.2 entitled “Spatio-energetic cross-talk in photon counting detectors: Numerical detector model (PcTK) and workflow for CT image quality assessment.” The paper has been published in the Medical Physics online (link added, 3/15/2018).

This paper is the first to describe our Photon Counting Toolkit (PcTK) version 3.2 and CT workflow in great details that allows users to assess the image quality of photon counting CT. We hope that this paper will attract more CT researchers to our PcTK, and in turn, help them with their projects.

We wish to express our sincere gratitude to our collaborators in the Siemens Healthineers. There would not be PcTK if not for their challenges and help. And once again, we thank them for their generously getting on board with making PcTK available to academic researchers.

We will present 2 papers during SPIE Medical Imaging 2018, February 10–15, Houston, TX.

1. PcTK and CT workflow will be presented as an oral presentation 10573-35, 3:50–4:10 pm, Feb 13 (Tue), Salon C in Session 7 (Photon Counting Detectors).
2. The effect of correlated noise and spectral distortion with NxN pixel binning and anti-scatter collimators (or sub-pixel masking) will be analyzed using PcTK. It will be presented as a poster 10573-183, 5:30–7:00 pm, Feb 14 (Wed), Salon E in Session PS10 (Posters: Photon-Counting Imaging).

We look forward to seeing you there.

Photon counting Toolkit (PcTK) is going live! We hope many will benefit from the release and the field will advance quickly.