Improved X-ray Cargo imaging by innovative background scattering quantification
Lead Research Organisation:
University of Manchester
Department Name: Physics and Astronomy
Abstract
X-ray screening is high priority for securing borders from the influx of firearms, narcotics, and contraband. The ability of an
x-ray screening system to detect photons attenuated by dense cargo directly affects the radiographic image quality that an
operator uses to identify such illicit material. When screening cargo and vehicles, high-energy high-dose pulsed linear
accelerators are used to generate the x rays. The detection package integrates the signal over the duration of a single
pulse and this forms the basis of each pixel value in the image. However, with no means to reject low-energy photons
scattered into the detectors or electronic dark current, the signals include a large degree of noise that distorts the final
radiographic images. The technological advances in recent years and the exploitation of spectroscopic techniques present
an opportunity to utilise novel detector material and off-the-shelf fast electronic components to identify individual photons.
This will vastly improve the performance of screening systems and increase image quality, particularly in areas of high
attenuation. To this end, this project seeks to investigate new detector material, design, construct and test a prototype
detection system capable of photon counting in such high x-ray flux environments. Detector characterisation and design will
be carried out at the University of Manchester. Experimental investigations will require the use of the new Compact Linac
facility at Daresbury laboratory, capable of producing low-dose x-ray pulses so that algorithms to control the detection
package can be developed and the limitations obtained. The detection package will then be used at Rapiscan Systems
facility at Stoke using a field-ready linac to prove its capabilities.
x-ray screening system to detect photons attenuated by dense cargo directly affects the radiographic image quality that an
operator uses to identify such illicit material. When screening cargo and vehicles, high-energy high-dose pulsed linear
accelerators are used to generate the x rays. The detection package integrates the signal over the duration of a single
pulse and this forms the basis of each pixel value in the image. However, with no means to reject low-energy photons
scattered into the detectors or electronic dark current, the signals include a large degree of noise that distorts the final
radiographic images. The technological advances in recent years and the exploitation of spectroscopic techniques present
an opportunity to utilise novel detector material and off-the-shelf fast electronic components to identify individual photons.
This will vastly improve the performance of screening systems and increase image quality, particularly in areas of high
attenuation. To this end, this project seeks to investigate new detector material, design, construct and test a prototype
detection system capable of photon counting in such high x-ray flux environments. Detector characterisation and design will
be carried out at the University of Manchester. Experimental investigations will require the use of the new Compact Linac
facility at Daresbury laboratory, capable of producing low-dose x-ray pulses so that algorithms to control the detection
package can be developed and the limitations obtained. The detection package will then be used at Rapiscan Systems
facility at Stoke using a field-ready linac to prove its capabilities.
People |
ORCID iD |
David Matthew Cullen (Principal Investigator) |
Description | The research was carried out in conjunction with Rapiscan Systems and the research findings are being taken forward with new research proposals. |
First Year Of Impact | 2021 |
Sector | Security and Diplomacy |
Description | SPIE Defense and Commercial Sensing 2020 Conference Student Travel Grant |
Amount | $750 (USD) |
Funding ID | 11404-10 |
Organisation | SPIE Europe |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 03/2020 |
End | 04/2020 |
Description | Virtual 2020 IEEE NSS MIC Conference Trainee Grant |
Amount | $150 (USD) |
Organisation | Institute of Electrical and Electronics Engineers (IEEE) |
Sector | Learned Society |
Country | United States |
Start | 09/2020 |
End | 11/2020 |
Title | A new Monte-Carlo simulation for X-ray measurements on the Compact linac at Daresbury Labs. |
Description | A new Monte-Carlo simulation has been developed. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2021 |
Provided To Others? | No |
Impact | None yet. |
Title | Upgrades to existing aquisition system to support background scatter detectors |
Description | Building upon the initial project aim to improve the quality of x-ray images as measured by the signal-to-noise ratio, the acquisition system has been upgraded to support data from two newly built SiPM detectors. This enabled the collection of background scatter data during an experiment at Daresbury Laboratory in November 2020. This additional data will allow the validation of realistic Monte-Carlo simulation codes which, in turn, will allow probing of the conditions of our original in-beam detector with more information than is available from recorded data alone - e.g. x-ray tracks. This additional information will be used to better estimate the total number of recorded x-rays in the in-beam detector that have scattered (a large contributor to the signal noise) before detection. The result will be an improved signal to noise ratio of the final intensity measurement. |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2020 |
Provided To Others? | No |
Impact | The new system has enabled the collection of a data set with background measurements of x-ray scatter for transmission x-ray detection. The analysis of this new data set is ongoing. |
Description | RAPISCAN Systems Limited |
Organisation | Rapiscan Systems |
Country | United States |
Sector | Private |
PI Contribution | We have undertaken research to better understand the backscattering of X-rays from different materials to work out a way of identifying illicit materials. |
Collaborator Contribution | Rapiscan systems have provided access to high-powered linacs to supply X-rays and scattering objects. |
Impact | This grant has only been operating for a year and data are still being analysed. |
Start Year | 2018 |
Title | C/C++ program to reduce waveform data in Total Data Readout format |
Description | A program was developed to allow real-time analyses of signal waveforms and interface with the MIDAS data acquisition software from Daresbury Laboratory. Using a MIDAS library, a live view of the data buffer can be obtained during the acquisition of data. Alternately, the program can read pre-recorded data from a file. The program supports multi-threaded computations, with MIDAS data blocks being read in and processed in parallel. Recorded waveforms are reduced to a recorded energy, a timestamp and a detector ID and output into ROOT format for subsequent analyses. |
Type Of Technology | Detection Devices |
Year Produced | 2019 |
Impact | The program has been used to analyse recorded data from an experiment at Daresbury in November/December 2019. Insights gained during that analysis were used to improve the detector design for another experiment in November 2020. The analysis of that experiment is ongoing. |