Sometimes in research it takes a lot of effort, time and patience to get something running. But then when it runs – the satisfaction is granted.
It has been exactly 5 years since the Data Acquisition System for the first J-PET prototype said *beep* and provided first tomography data from the scanner constructed out of plastic scintillators.
During these 5 years, we designed, constructed and eventually successfully launched a completely new vision of PET tomography – a lightweight, modular scanner with a compact and powerful data processing system.
24 modules have 13 plastic scintillator strips and 54 SiPMs on each end. The signals they generate are registered by Artix7 based front end boards that digitize the signals and send the data to 4 data concentrators which are Virtex Ultrascale VCU108 boards from Xilinx. The entire system is controlled by a single Zynq Ultrascale+ ZCU102 board – all interconnected and synchronized by a ton of optical links.
The concentrator boards preprocess the raw data extracting time coincidences, applying calibrations and converting it into reconstructed interaction points on the modules. Such data stream is sent to the storage using UDP and 10GbE links but additionally transferred to the controller board for to be developed real-time image reconstruction. At this moment we have the software visualization using J-PET Software Framework which delivers first insight into the data – a radioactive source placed in the center of the barrel.
It’s something! Now we design a system for a Total-Body Tomography – a scanner capable of monitoring radiopharmaceutical marker distribution over the entire human body in a single shot.
Together with the official annoucement of the J-PET Lab opening [link] we are shifting up a gear: there is plenty of FPGA related development, both in low level RTL and HLS. If you are interested, have a look at diploma projects tab or email directly at email@example.com
It was a great pleasure for me to attend Summer XLII-nd IEEE-SPIE Joint Symposium on Photonics, Web Engineering, Electronics for Astronomy and High Energy Physics Experiments presenting DAQ system of PET tomography devices developed by our team. http://wilga.ise.pw.edu.pl/
The conference takes place in Warsaw University of Technology Wilga Village, where attendees are accommodated. Quiet and full of nature terrains aids concentration and provides space to relax and chill out after scientific activities.
Enhanced image reconstruction, including 3D and TOF functionalities has been successfully implemented entirely in the FPGA!
In programmable logic, we are finding LOR candidates and reconstruct the annihilation point coordinates. Then, only X, Y, Z values are being sent from the JPET Controller to the server that produces 3D canvas with the scanner visualization.
You can find a video showing it in action under [this] link.
Implementation of image reconstruction from tomographic data has been presented for the first time to external experts in tomography at two conferences. First one was XL IEEE-SPIE Joint Symposium Wilga 2017 and the second one was 2nd Jagiellonian Symposium on Fundamental and Subatomic Physics
The project received much interest from the experts from USA universities and was reviewed as having much potential in development of true innovative solutions, not existing on market so far.
Another step into tomographic image reconstruction in real time has been made!
JPET Controller allows to process data from 8 TRBv3s in several steps leading to image creation:
Receive and synchronize data units from the TRBv3s
Hit data extraction
Detector geometry mapping
LOR coordinates calculation
All those steps, performed 50 000 times per second, processing hundreds MB per second reduce the data volume to hundreds of KB and limit the processing on the CPU only to drawing points. All this on a single Xilinx Zynq.
Next steps are:
Introduction of calibration parameters
3rd dimension Z-Axis
Under this [link] you can find a video that shows reconstructed image being drawn in real time as the radioactive source on robotic arm scans the detector.
First images have been produced by JPET Controller board!
The controller processes data streams from 8 TRBs, parses the TDC data and recovers hits on scintillators. The hits are correlated together by scanning with a time window and then mapped into the detector geometry in order to recover LOR coordinates. Finally instead of raw TDC data only two points from LOR are being sent.