Implementation of the Weighted L1-Norm Scatter Correction Scheme in Dual-Energy Radiography

Lim, Young-Wook; Kim, Guna; Park, Chulkyu; Cho, Hyosung; Kang, Soo‐Hwan; Kim, Kyuseok; Park, Jeongeun; Lee, Dongyeon; Park, Soyoung; Lim, Hyunwoo; Lee, Hunwoo; Jeon, Duhee; Kim, Woo-Sung; Seo, Changwoo

doi:10.3938/jkps.74.414

Cited by 3 publications

(3 citation statements)

References 17 publications

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“…Such an approach could prove problematic in clinical practice since bony structures generate and absorb scatter differently from soft tissue. In 26 – 30 , the authors evaluated the image dehazing method proposed by Meng et al 31 to obtain a scatter map in radiography based on the alternating direction method of multipliers (ADMM) 32 . However, simultaneous correction of lungs and spine in chest radiography was not possible because of the need for a specific parameter that had to be empirically tuned depending on the intensity of each region.…”

Section: Introductionmentioning

confidence: 99%

“…However, simultaneous correction of lungs and spine in chest radiography was not possible because of the need for a specific parameter that had to be empirically tuned depending on the intensity of each region. Similar approaches were proposed for dual energy acquisitions, applying the ADMM algorithm prior to base material decomposition 30 .…”

Section: Introductionmentioning

confidence: 99%

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A novel beam stopper-based approach for scatter correction in digital planar radiography

Sakaltras

Pena

Martinez

et al. 2023

Sci Rep

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X-ray scatter in planar radiography degrades the contrast resolution of the image, thus reducing its diagnostic utility. Antiscatter grids partially block scattered photons at the cost of increasing the dose delivered by two- to four-fold and posing geometrical restrictions that hinder their use for other acquisition settings, such as portable radiography. The few software-based approaches investigated for planar radiography mainly estimate the scatter map from a low-frequency version of the image. We present a novel method for scatter correction in planar imaging based on direct patient measurements. Samples from the shadowed regions of an additional partially obstructed projection acquired with a beam stopper placed between the X-ray source and the patient are used to estimate the scatter map. Evaluation with simulated and real data showed an increase in contrast resolution for both lung and spine and recovery of ground truth values superior to those of three recently proposed methods. Our method avoids the biases of post-processing methods and yields results similar to those for an antiscatter grid while removing geometrical restrictions at around half the radiation dose. It can be used in unconventional imaging techniques, such as portable radiography, where training datasets needed for deep-learning approaches would be very difficult to obtain.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A novel beam stopper-based approach for scatter correction in digital planar radiography

Sakaltras

Pena

Martinez

et al. 2023

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Alternatively, decomposition methods use higher‐order models to associate the tissue maps corresponding to soft tissue and bone, x s and x b , with the natural logarithm of the measured photons at the detector over the total incident photons, d L and d H (second order, 9–13 third order 14–17 or other models such as conic and cubic surface equations 18 ):

x_{s} = {false\sum}_{m = 0}^{M} \sum_{n = 0}^{N} q_{italicmn} d_{L}^{m} d_{H}^{n} ; x_{b} = {false\sum}_{m = 0}^{M} \sum_{n = 0}^{N} r_{italicmn} d_{L}^{m} d_{H}^{n}

d_{L} (t_{s}, t_{b}) = L n (I_{L} / \int N_{L} (ε) d ε) ; d_{H} (t_{s}, t_{b}) = L n (I_{H} / \int N_{H} (ε) d ε)

The model parameters q mn and r mn can be obtained from a calibration step by acquiring different known combinations of x s and x b at low and high energies, which correspond to d L and d H . The equivalent materials used for the calibration need to resemble the attenuation of X‐rays by soft tissue and bone for different energies, which can be represented by the dual‐material dependency with the energy, DMD(x s , x b ) , shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a calibration phantom for quantitative radiography

et al. 2021

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Objective Dual energy radiography (DER) makes it possible to obtain separate images for soft‐tissue and bony structures (tissue maps) based on the acquisition of two radiographs at different source peak‐kilovoltage values. Current DER studies are based on the weighted subtraction method, which requires either manual tuning or the use of precomputed tables, or on decomposition methods, which make use of a calibration to model soft‐tissue and bone components. In this study, we examined in depth the optimum method to perform this calibration. Methods We used simulations to optimize the calibration protocol and evaluated the effect of the material and size of a calibration phantom composed of two wedges and its positioning in the system. Evaluated materials were water, PMMA and A‐150 as soft‐tissue equivalent, and Teflon, B‐100 and aluminum as bone equivalent, with sizes from 5 to 30 cm. Each material combination was compared with an ideal phantom composed of soft tissue and bone. Our simulation results enabled us to propose four designs that were tested with the NOVA FA X‐ray system with a realistic thorax phantom. Results Calibration based on a very simple and inexpensive phantom with no strict requirements in its placement results in appropriate separation of the spine (a common focus in densitometry studies) and the identification of nodules as small as 6 mm, which have been reported to have a low rate of detection in radiography. Conclusion The proposed method is completely automatic, avoiding the need for a radiology technician with expert knowledge of the protocol, as is the case in densitometry exams. The method provides real mass thickness values, enabling quantitative planar studies instead of relative comparisons.

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Feasibility study of deep-learning-based bone suppression incorporated with single-energy material decomposition technique in chest X-rays

Lim

Lee

Cho

et al. 2022

BJR

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Objective: To improve the detection of lung abnormalities in chest X-rays by accurately suppressing overlapping bone structures in the lung area. According to literature on missed lung cancer in chest X-rays, such structures are a significant cause of chest-related diagnostic errors. Methods This study presents a deep-learning-based bone suppression method where a residual U-Net model is trained for chest X-rays using dataset generated from the single-energy material decomposition (SEMD) technique on computed tomography (CT). Synthetic projection images and soft-tissue selective images were obtained from the CT dataset via the SEMD, which were then used as the input and label data of the U-Net network. The trained network was tested on synthetic chest X-rays and two real chest radiographs. Results: Bone-suppressed images of the real chest radiographs obtained by the proposed method were similar to the results from the AAPM lung CT data; pulmonary nodules in the soft-tissue selective images appeared more clearly than in the synthetic projection images. The PSNR and SSIM values measured between the output and the corresponding label images were approximately 17.85 and 0.90, respectively. Conclusions: The proposed method effectively yielded bone-suppressed chest X-ray images, indicating its clinical usefulness, and it can improve the detection of lung abnormalities in chest X-rays. Advances in knowledge: The idea of using SEMD to obtain large amounts of paired images for deep-learning-based bone suppression algorithms is novel.

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Implementation of the Weighted L1-Norm Scatter Correction Scheme in Dual-Energy Radiography

Cited by 3 publications

References 17 publications

A novel beam stopper-based approach for scatter correction in digital planar radiography

A novel beam stopper-based approach for scatter correction in digital planar radiography

Optimization of a calibration phantom for quantitative radiography

Feasibility study of deep-learning-based bone suppression incorporated with single-energy material decomposition technique in chest X-rays

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