Novel X-ray backscatter technique for detection of dangerous materials: application to aviation and port security

Abstract.A special slit collimator was developed earlier for fast acquisition of X-ray back scatter images. The design was based on a twisted slit design (ruled surfaces) in a Tungsten block to acquire backscatter images. The comparison with alternative techniques as flying spot and coded aperture pin hole technique could not prove the expected higher contrast sensitivity. In analogy to the coded aperture technique, a novel multi slit camera was designed and tested. Several twisted slits were parallelly arranged in a metal block. The CAD design of different multi-slit cameras was evaluated and optimized by the computer simulation packages aRTist and McRay. The camera projects a set of equal images, one per slit, to the digital detector array, which are overlaying each other. Afterwards, the aperture is corrected based on a deconvolution algorithm to focus the overlaying projections into a single representation of the object. Furthermore, a correction of the geometrical distortions due to the slit geometry is performed. The expected increase of the contrast-to-noise ratio is proportional to the square root of the number of parallel slits in the camera. However, additional noise has to be considered originating from the deconvolution operation. The slit design, functional principle, and the expected limits of this technique are discussed.

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“…Alternatively to the flying spot technology [18] the diaphragm based camera was explored for applications in NDT [14,19,20]. Fig.…”

Section: Application Of Twisted Slit Camera For Testing Of Cfrp Compomentioning

confidence: 99%

A novel multi slit X-ray backscatter camera based on synthetic aperture focusing

Wieder¹,

Ewert²,

Vogel³

et al. 2017

AIP Conference Proceedings

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“…One of the main developments in homeland security has been the use of X-ray backscattering devices to detect non-metallic objects more efficiently. Due to the high sensitivity of this technique for detecting low atomic number materials, it is used to seek the presence of suspicious objects such as plastic explosives and contraband cargo [2,3]. These X-ray devices are meant to be used in places with the potential presence of people, leading to a high risk of accidental exposure.…”

Section: Introductionmentioning

confidence: 99%

Dose estimation in X-ray backscatter imaging with Timepix3 and TLD detectors

et al. 2023

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Nowadays, the detection of backscatter X-rays has become an essential part of road security scanners, where individuals are at risk of an accidental exposure to the pulsed photon radiation fields generated by the devices that implement this technique. Dose to soft-tissue measurements of a pulsed radiation field generated by a commercial cargo X-ray backscattering device are presented using a Timepix3 detector. To accurately estimate the imparted dose, the energy spectrum of a backscattering cargo scanner is measured with a thick CdZnTe hybrid semiconductor pixel detector. The deconvolution of this measured spectrum is performed and the contributions to the dose are calculated by means of the mass energy-absorption coefficients for soft-tissue. This methodology was assessed through a Monte-Carlo simulation, together with verification measurements using thermoluminescent detectors (TLDs) as a standard dosimetry system. Measurements of direct irradiation, for a 30 s scan with the device at 2 m from the detector, yielded a dose of (4.9 ± 0.7) μGy and (3.6 ± 0.3) μGy for the Timepix3 and TLDs, respectively. In a simulated cargo environment, with the detector behind a 1 mm thick steel wall, 30 s scan time, and 2 m source to detector distance, the dose measured by the Timepix3 was (1.7 ± 0.1) μGy, while for the TLDs (1.4 ± 0.6) μGy, showing that the proposed methodology has a similar response as compared to a standard dosimetry system.

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“…X-ray backscatter imaging (XBI) technology has attracted a lot of attention during the turn of the century and it has been applied for vehicle surveillance, IED detections and for detection of buried objects such as land mines. Unlike conventional transmission X-ray, which is more sensitive for detecting high atomic number material [1][2][3], BAXI relies on the Compton scattering of the X-ray with the core electrons [1,2,4,5], and is more sensitive to low atomic number materials like explosives [2,6]. Furthermore, BAXI is more attractive in operations as both the X-ray source and detector are mounted in the same housing; thereby, it can scan large objects [7].…”

Section: Introduction 11 Backscatter X-ray Imaging (Baxi)mentioning

confidence: 99%