Novel detector design for reducing intercell x‐ray cross‐talk in the variable resolution x‐ray CT scanner: A Monte Carlo study

Abstract

Purpose:The variable resolution x-ray ͑VRX͒ CT scanner provides substantial improvement in the spatial resolution by matching the scanner's field of view ͑FOV͒ to the size of the object being imaged. Intercell x-ray cross-talk is one of the most important factors limiting the spatial resolution of the VRX detector. In this work, a new cell arrangement in the VRX detector is suggested to decrease the intercell x-ray cross-talk. The idea is to orient the detector cells toward the opening end of the detector. Methods: Monte Carlo simulations were used for performance assessment of the oriented cell detector design. Previously published design parameters and simulation results of x-ray cross-talk for the VRX detector were used for model validation using the GATE Monte Carlo package. In the first step, the intercell x-ray cross-talk of the actual VRX detector model was calculated as a function of the FOV. The obtained results indicated an optimum cell orientation angle of 28°to minimize the x-ray cross-talk in the VRX detector. Thereafter, the intercell x-ray cross-talk in the oriented cell detector was modeled and quantified. Results:The intercell x-ray cross-talk in the actual detector model was considerably high, reaching up to 12% at FOVs from 24 to 38 cm. The x-ray cross-talk in the oriented cell detector was less than 5% for all possible FOVs, except 40 cm ͑maximum FOV͒. The oriented cell detector could provide considerable decrease in the intercell x-ray cross-talk for the VRX detector, thus leading to significant improvement in the spatial resolution and reduction in the spatial resolution nonuniformity across the detector length. Conclusions: The proposed oriented cell detector is the first dedicated detector design for the VRX CT scanners. Application of this concept to multislice and flat-panel VRX detectors would also result in higher spatial resolution.

Design and construction of a variable resolution cone-beam small animal mini-CT prototype for in vivo studies

“…In this mini-CT scanner, the variable spatial resolution solely arises from modification of magnification. It should be noted that the higher magnification tends to only improve the sampling resolution of the detector while having adverse impact on geometric unsharpness (Arabi et al, 2010(Arabi et al, , 2011. Geometric unsharpness refers to the loss of definition since the x-ray beam does not originate from an infinite point source but rather over an area.…”

“…Firstly, apart from the mechanical complexity, angulation of the detector with respect to the incident x-ray beam causes significant magnification nonuniformity (and consequently spatial resolution non-uniformity) from one end of the detector to the other. Moreover, due to the non- perpendicular angle between the incident x-ray beam and the detector, the cross-talk between detector cells increased remarkably which adversely influence the scanner's spatial resolution (Arabi et al, 2011). Since the variable spatial resolution is achieved through modifying the system magnification, no magnification non-uniformity across the detector and no additional inter-cells cross-talk occurs when the scanner's FOV changes.…”

Monte Carlo-based assessment of the trade-off between spatial resolution, field-of-view and scattered radiation in the variable resolution X-ray CT scanner

“…The opposite arm was constructed from a uniform material in such a way that the detector had the same X-ray attenuation properties of the original one. This Monte Carlo model was validated in previous studies [7,10].…”

Comparison of the X-ray tube spectrum measurement using BGO, NaI, LYSO, and HPGe detectors in a preclinical mini-CT scanner: Monte Carlo simulation and practical experiment

“…There have been always interests in designing detectors with the highest possible sensitivity (to detect very low activity concentration) and high spatial resolution (to localize the spatial distribution of the activity concentration). Normally, there is a fundamental tradeoff between improvements in sensitivity and spatial resolution of a detector, wherein strategies such as reducing the field of view (FOV) or modifying the distances between detector, object, and X-ray source (variable magnification) have been adopted to find an optimal compromise between these two key parameters (Lohrabian et al, 2019;Arabi et al, 2015;Arabi, KAMALIASL, Aghamiri;Kamali-Asl et al, 2009;Arabi et al, 2011;Sanaat et al, 2020).…”