Journal of X-Ray Science and Technology - Volume 30, issue 4

Authors: Dong, Fangfen | Weng, Xing | Deng, Xianzhi | Yang, Yong | Xu, Benhua | Li, Xiaobo

Article Type: Research Article

Abstract: OBJECTIVE: To investigate clinical utility of a new immobilization method in image-guided intensity-modulated radiotherapy (IMRT) for breast cancer patients after radical mastectomy. MATERIALS AND METHODS: Forty patients with breast cancer who underwent radical mastectomy and postoperative IMRT were prospectively enrolled. The patients were randomly and equally divided into two groups using both a carbon-fiber support board and a hollowed-out cervicothoracic thermoplastic mask (Group A) and using only the board (Group B). An iSCOUT image-guided system was used for acquiring and correcting pretreatment setup errors for each treatment fraction. Initial setup errors and residual errors were obtained by aligning …iSCOUT images with digitally reconstructed radiograph (DRR) images generated from planning CT. Totally 600 initial and residual errors were compared and analyzed between two groups, and the planning target volume (PTV) margins before and after the image-guided correction were calculated. RESULTS: The initial setup errors of Group A and Group B were (3.14±3.07), (2.21±1.92), (2.45±1.92) mm and (3.14±2.97), (2.94±3.35), (2.80±2.47) mm in the left-right (LAT), superior-inferior (LONG), anterior-posterior (VERT) directions, respectively. The initial errors in Group A were smaller than those in Group B in the LONG direction (P  < 0.05). No significant difference was found in the distribution of three initial error ranges (≤3 mm, 3–5 mm and > 5 mm) in each of the three translational directions for the two groups (P  > 0.05). The residual errors of Group A and Group B were (1.74±1.03), (1.62±0.92), (1.66±0.91) mm and (1.70±0.97), (1.68±1.18), (1.58±0.98) mm in the three translational directions, respectively. No significant difference was found in the residual errors between two groups (P  > 0.05). With the image-guided correction, PTV margins were reduced from 8.01, 5.44, 5.45 mm to 3.54, 2.99, 2.89 mm in three translational directions of Group A, respectively, and from 8.14, 10.89, 6.29 mm to 2.67, 3.64, 2.74 mm in those of Group B, respectively. CONCLUSION: The use of hollowed-out cervicothoracic thermoplastic masks combined with a carbon-fiber support board showed better inter-fraction immobilization than the single use of the board in reducing longitudinal setup errors for breast cancer patients after radical mastectomy during IMRT treatment course, which has potential to reduce setup errors and improve the pretreatment immobilization accuracy for breast cancer IMRT after radical mastectomy. Show more

Keywords: Immobilization device, breast cancer, intensity-modulated radiotherapy (IMRT), radical mastectomy, setup errors

DOI: 10.3233/XST-221127

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 641-655, 2022

Authors: Lu, Ming-Yi | Ting, Chien-Yi | Jao, Jo-Chi

Article Type: Research Article

Abstract: BACKGROUND: Medical imaging plays a crucial role in modern medicine. In order to provide fast and accurate medical diagnosis, computed tomography (CT) is a commonly used tool in radiological examinations, and 640-slice CT is the most advanced CT imaging modality. OBJECTIVE: To evaluate the radiation dose and the risk under 640-slice abdominal CT examination. METHODS: Examinations were performed using a 640-slice CT scanner on an Alderson-Rando anthropomorphic phantom. The used scanning acquisition parameters were the same as those used on abdominal examination without contrast medium injection in clinical practice. To measure the absorbed doses, optically stimulated …luminescence dosimeters (OSLDs) were put into liver, stomach, bladder, gonads, colon, small intestine, bone marrow, and skin. RESULTS: According to the 1990 Recommendations of the International Commission on Radiological Protection (ICRP Publication 60), the calculated effective doses received from this examination were 0.90 mSv in males and 0.89 mSv in females. According to the 2007 Recommendations of the International Commission on Radiological Protection (ICRP Publication 103), the calculated effective dose received from this examination was 0.83 mSv in both sexes. CONCLUSIONS: Radiation doses obtained from the abdominal 640-slice CT examination are lower than the yearly cumulative doses received from natural radiation, revealing there is no deterministic effect and radiation risk is relatively low; therefore, this CT examination is considered safe. Show more

Keywords: 640-slice CT, OSLD, alderson-rando anthropomorphic phantom, radiation dose, abdominal CT

DOI: 10.3233/XST-211101

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 657-666, 2022

Authors: Romero, Ignacio O. | Fang, Yile | Li, Changqing

Article Type: Research Article

Abstract: BACKGROUND: X-ray image quality relies heavily on the emitted X-ray photon number which depends on X-ray tube current and exposure time. To accurately estimate the absorbed dose in an imaging protocol, it is better to simulate the X-ray imaging with a Monte Carlo platform such as GATE (Geant4 Application for Tomographic Emission). Although input of GATE is the X-ray photon number of the simulated X-ray tube, it lacks a good way to setup the photon number for a desired X-ray tube current setting. OBJECTIVE: To provide a method to correlate the experimental X-ray tube current exposure time and …the X-ray photon number in GATE. METHODS: The accumulated radiation dose of a micro-computed tomography (CT) X-ray tube was recorded at different current exposure times with a general-purpose ion chamber. GATE was used to model the experimental microCT imaging system and calculate the total absorbed dose (cGy) in the sensitive volume of the ion chamber with different X-ray photon numbers. Linear regression models are used to establish a correlation between the estimated X-ray photon number and the X-ray tube settings. At first, one model establishes the relationship between the experimentally measured dose and the X-ray tube setting. Then, another model establishes a relationship between the simulated dose and the X-ray number in GATE. At last, by correlating these two models, a regression model to estimate the X-ray output number from an experimental X-ray tube setting (mAs) is obtained. RESULTS: For a typical micro-CT scan, the X-ray tube is operated at 50 kVp and 0.5 mA for a 500 ms exposure time per projection (0.25 mAs). For these X-ray imaging parameters, the X-ray number per projection is estimated to be 3.613×106 with 1.0 mm Al filter. CONCLUSION: The findings of this work provide an approach to correlate the experimental X-ray tube current exposure time to the X-ray photon number in the GATE simulation of the X-ray tube to more accurately determine radiation dose for an imaging protocol. Show more

Keywords: X-ray imaging, GATE, Monte Carlo

DOI: 10.3233/XST-221126

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 667-675, 2022

Authors: Duan, Jinghao | Guo, Ran | Wei, Wenqiang | Zhu, Jian | Qiu, Qingtao | Zhang, Ruohui | Meng, Xiangjuan

Article Type: Research Article

Abstract: OBJECTIVE: To investigate the following hypotheses: (1) ExacTrac X-ray Snap Verification (ET-SV) is an alternative to CBCT for positioning patients with esophageal carcinoma (EC), (2) ET-SV can detect displacement in EC patients during radiotherapy (RT) and (3) EC patients can be feasibly monitored in quasi-real-time with ET-SV during RT. METHODS: Anthropomorphic phantoms and 13 patients were included in this study. CBCT and ET-SV were both implemented before treatment delivery to detect displacement, and their correction results were compared. For the patient tests, positional correction in 3 translational directions and the yaw direction were applied using the ET-SV correction …results. The residual error was detected immediately using ET-SV. Finally, to acquire the intrafractional motion, ET-SV was implemented when the gantry was at 0°, 90°, 180° and 270°, respectively. RESULTS: In phantom tests, the maximum value of the difference in displacement between the CBCT and ET systems was 1.16 mm for translation and 0.31° for yaw. According to Bland–Altman analysis of the patient test results, 5% (5/98), 5% (5/98), 5% (5/98), and 4% (4/98) of points were beyond the upper and lower limits of agreement in the AP, SI, LR and yaw directions, respectively. The mean residual error was –0.482 mm, 1.215 mm, 1.0 mm, –0.487°, 0.105°, and 0.003° in the AP, SI, LR, pitch, roll and yaw directions, respectively. The intrafractional displacement ranged from –0.21 mm to 0 mm for translation and from –0.63° to 0.21° for rotation. The mean total translational error for intrafractional motion increased from 0.47 mm to 1.14 mm during the treatment. CONCLUSION: The accuracy of ET-SV for EC RT positional correction is comparable to that of CBCT. Thus, Quasi-real-time intrafractional monitoring can be used to detect EC patient displacement during radiotherapy. Show more

Keywords: Quasi-real-time monitoring, esophageal cancer, ExacTrac X-ray Snap

DOI: 10.3233/XST-221165

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 677-687, 2022

Authors: Zhang, Tianle | Zhao, Sai | Liu, Yiwen | Liu, Zhichao | Ma, Zepeng | Zuo, Ziwei | Zhao, Yongxia

Article Type: Research Article

Abstract: OBJECTIVES: To compare image quality and radiation dose of computed tomography angiography (CTA) of the head and neck in patients using two Gemstone Spectral Imaging (GSI) scanning protocols. METHODS: A total of 100 patients who underwent head-neck CTA were divided into two groups (A and B) according to the scanning protocols, with 50 patients in each group. The patients in group A underwent GSI scanning protocol 1 (GSI profile: head and neck CTA), while those in group B underwent GSI scanning protocol 2 (GSI profile: chest 80 mm). All images were reconstructed using 40% and 70% pre- and post-adaptive …level statistical iterative reconstruction V (pre-ASiR-V and post-ASiR-V) algorithms, respectively. The CT dose index (CTDIvol) and dose-length (DLP) product were recorded and the mean value was calculated and converted to the effective dose. CT values, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of all images were calculated. Additionally, subjective image evaluation was conducted by two independent radiologists using a five-point scoring method. All data were statistically analyzed. RESULTS: There were no significant differences in the CT values, SNR, CNR, and subjective score between groups A and B (p  > 0.05); however, the mean effective dose (1.2±0.1 mSv) in group B was 45.5% lower than that in group A (2.2±0.2 mSv) (p  < 0.05). CONCLUSIONS: GSI scanning protocol 2 could more effectively reduce the radiation dose in head-neck CT angiography while maintaining image quality compared to GSI scanning protocol 1. Show more

Keywords: GSI scan protocol, head-neck CTA, image quality, radiation dose assessment

DOI: 10.3233/XST-221181

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 689-696, 2022

Authors: Lee, Moo Seok | Kim, Gyeong Rip | Kim, Sang Sik | Lee, Jong Kyu | Kim, Wontaek | Kwak, Jong Hyeok | Kil, Sang Hyeong | Kim, Gun Do

Article Type: Research Article

Abstract: In this study, the electrical resistance of the whole body and histological changes of skeletal muscle were investigated in rats according to the increase in radiation dose. A total of 15 male Sprague–Dawley rats (5-weeks-old) were randomly divided into 5 groups (each, n  = 3). Each group received 1 Gy, 5 Gy, 10 Gy and 20 Gy systemic exposure, and the non-irradiated group was used as a control for morphological comparison. After attaching an electrode clip to the forelimb of the rat, an AC frequency was applied before and 4 days after irradiation using an impedance/gain-phase analyzer, and the measurement system was automatically controlled with …LabVIEW. Comparing to before irradiation after 4 days, the difference in the average impedance values at 1 Gy, 5 Gy, 10 Gy, and 20 Gy was 1188±989 ohm, 3076±2251 ohm, 7650±6836 ohm, and 10478±6250 ohm, respectively. By comparing the normal group and the experimental group, muscle fiber atrophy and collagen fibers around blood vessels were observed (p  < 0.05, control group vs 5 Gy or more high-dose group). These results confirmed the previously reported morphological changes of skeletal muscle and our hypothesis that whole-body impedance measurement enables to reflect tissue changes after irradiation. Show more

Keywords: Ionizing radiation, electrical signal, collagen, histological changes

DOI: 10.3233/XST-211122

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 697-708, 2022

Authors: Liu, Yuhang | Liu, Yi | Zhang, Pengcheng | Zhang, Quan | Wang, Lei | Yan, Rongbiao | Li, Wenqiang | Gui, Zhiguo

Article Type: Research Article

Abstract: The objective of this study is to apply an improved Faster-RCNN model in order to solve the problems of low detection accuracy and slow detection speed in spark plug defect detection. In detail, an attention module based symmetrical convolutional network (ASCN) is designed as the backbone to extract multi-scale features. Then, a multi-scale region generation network (MRPN), in which InceptionV2 is used to achieve sliding windows of different scales instead of a single sliding window, is proposed and tested. Additionally, a dataset of X-ray spark plug images is established, which contains 1,402 images. These images are divided into two subsets …with a ratio of 4:1 for training and testing the improved Faster-RCNN model, respectively. The proposed model is transferred and learned on the pre-training model of MS COCO dataset. In the test experiments, the proposed method achieves an average accuracy of 89% and a recall of 97%. Compared with other Faster-RCNN models, YOLOv3, SSD and RetinaNet, our proposed new method improves the average accuracy by more than 6% and the recall by more than 2%. Furthermore, the new method can detect at 20fps when the input image size is 1024×1024×3 and can also be used for real-time automatic detection of spark plug defects. Show more

Keywords: Defect detection, attention module, inceptionV2, faster-RCNN, spark plug

DOI: 10.3233/XST-211120

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 709-724, 2022

Authors: Cong, Wenxiang | De Man, Bruno | Wang, Ge

Article Type: Research Article

Abstract: Dual-energy computed tomography (DECT) acquires two x-ray projection datasets with different x-ray energy spectra, performs material-specific image reconstruction based on the energy-dependent non-linear integral model, and provides more accurate quantification of attenuation coefficients than single energy spectrum CT. In the diagnostic energy range, x-ray energy-dependent attenuation is mainly caused by photoelectric absorption and Compton scattering. Theoretically, these two physical components of the x-ray attenuation mechanism can be determined from two projection datasets with distinct energy spectra. Practically, the solution of the non-linear integral equation is complicated due to spectral uncertainty, detector sensitivity, and data noise. Conventional multivariable optimization methods are …prone to local minima. In this paper, we develop a new method for DECT image reconstruction in the projection domain. This method combines an analytic solution of a polynomial equation and a univariate optimization to solve the polychromatic non-linear integral equation. The polynomial equation of an odd order has a unique real solution with sufficient accuracy for image reconstruction, and the univariate optimization can achieve the global optimal solution, allowing accurate and stable projection decomposition for DECT. Numerical and physical phantom experiments are performed to demonstrate the effectiveness of the method in comparison with the state-of-the-art projection decomposition methods. As a result, the univariate optimization method yields a quality improvement of 15% for image reconstruction and substantial reduction of the computational time, as compared to the multivariable optimization methods. Show more

Keywords: Dual-energy computed tomography (DECT), polychromatic physical model, projection decomposition, material decomposition, monochromatic image reconstruction

DOI: 10.3233/XST-221153

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 725-736, 2022

Authors: Zhang, Shunli | Qiang, Yu

Article Type: Research Article

Abstract: In computed tomography (CT), the total variation (TV) constrained algebraic reconstruction technique (ART) can obtain better reconstruction quality when the projection data are sparse and noisy. However, the ART-TV algorithm remains time-consuming since it requires large numbers of iterations, especially for the reconstruction of high-resolution images. In this work, we propose a fast algorithm to calculate the system matrix for line intersection model and apply this algorithm to perform the forward-projection and back-projection operations of the ART. Then, we utilize the parallel computing techniques of multithreading and graphics processing units (GPU) to accelerate the ART iteration and the TV minimization, …respectively. Numerical experiments show that our proposed parallel implementation approach is very efficient and accurate. For the reconstruction of a 2048 × 2048 image from 180 projection views of 2048 detector bins, it takes about 2.2 seconds to perform one iteration of the ART-TV algorithm using our proposed approach on a ten-core platform. Experimental results demonstrate that our new approach achieves a speedup of 23 times over the conventional single-threaded CPU implementation that using the Siddon algorithm. Show more

Keywords: Computed tomography (CT), image reconstruction, algebraic reconstruction technique, total variation, parallel computing

DOI: 10.3233/XST-221163

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 737-750, 2022

Authors: Vijayakumar, K. | Rajinikanth, V. | Kirubakaran, M.K.

Article Type: Research Article

Abstract: BACKGROUND: The incidence rates of breast cancer in women community is progressively raising and the premature diagnosis is necessary to detect and cure the disease. OBJECTIVE: To develop a novel automated disuse detection framework to examine the Breast-Ultrasound-Images (BUI). METHODS: This scheme includes the following stages; (i) Image acquisition and resizing, (ii) Gaussian filter-based pre-processing, (iii) Handcrafted features extraction, (iv) Optimal feature selection with Mayfly Algorithm (MA), (v) Binary classification and validation. The dataset includes BUI extracted from 133 normal, 445 benign and 210 malignant cases. Each BUI is resized to 256×256×1 pixels and the resized …BUIs are used to develop and test the new scheme. Handcrafted feature-based cancer detection is employed and the parameters, such as Entropies, Local-Binary-Pattern (LBP) and Hu moments are considered. To avoid the over-fitting problem, a feature reduction procedure is also implemented with MA and the reduced feature sub-set is used to train and validate the classifiers developed in this research. RESULTS: The experiments were performed to classify BUIs between (i) normal and benign, (ii) normal and malignant, and (iii) benign and malignant cases. The results show that classification accuracy of > 94%, precision of > 92%, sensitivity of > 92% and specificity of > 90% are achieved applying the developed new schemes or framework. CONCLUSION: In this work, a machine-learning scheme is employed to detect/classify the disease using BUI and achieves promising results. In future, we will test the feasibility of implementing deep-learning method to this framework to further improve detection accuracy. Show more

Keywords: Breast cancer, ultrasound image, handcrafted features, mayfly algorithm, binary classification

DOI: 10.3233/XST-221136

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 751-766, 2022

Authors: Yang, You-Chang | Wei, Xiao-Yu | Tang, Xiao-Qiang | Yin, Ruo-Han | Zhang, Ming | Duan, Shao-Feng | Pan, Chang-Jie

Article Type: Research Article

Abstract: PURPOSE: To establish a machine-learning (ML) model based on coronary computed tomography angiography (CTA) images for evaluating myocardial ischemia in patients diagnosed with coronary atherosclerosis. METHODS: This retrospective analysis includes CTA images acquired from 110 patients. Among them, 58 have myocardial ischemia and 52 have normal myocardial blood supply. The patients are divided into training and test datasets with a ratio 7 : 3. Deep learning model-based CQK software is used to automatically segment myocardium on CTA images and extract texture features. Then, seven ML models are constructed to classify between myocardial ischemia and normal myocardial blood supply cases. Predictive …performance and stability of the classifiers are determined by receiver operating characteristic curve with cross validation. The optimal ML model is then validated using an independent test dataset. RESULTS: Accuracy and areas under ROC curves (AUC) obtained from the support vector machine with extreme gradient boosting linear method are 0.821 and 0.777, respectively, while accuracy and AUC achieved by the neural network (NN) method are 0.818 and 0.757, respectively. The naive Bayes model yields the highest sensitivity (0.942), and the random forest model yields the highest specificity (0.85). The k-nearest neighbors model yields the lowest accuracy (0.74). Additionally, NN model demonstrates the lowest relative standard deviations (0.16 for accuracy and 0.08 for AUC) indicating the high stability of this model, and its AUC applying to the independent test dataset is 0.72. CONCLUSION: The NN model demonstrates the best performance in predicting myocardial ischemia using radiomics features computed from CTA images, which suggests that this ML model has promising potential in guiding clinical decision-making. Show more

Keywords: Heart, machine learning, computed tomography angiography (CTA), myocardial ischemia

DOI: 10.3233/XST-221160

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 767-776, 2022

Authors: Sato, Mitsuru | Kondo, Yohan | Takahashi, Noriyuki | Ohmura, Tomomi | Takahashi, Naoya

Article Type: Research Article

Abstract: BACKGROUND: Head computed tomography (CT) is a commonly used imaging modality in radiology facilities. Since multiplanar reconstruction (MPR) processing can produce different results depending on the medical staff in charge, there is a possibility that the antemortem and postmortem images of the same person could be assessed and identified differently. OBJECTIVE: To propose and test a new automatic MPR method in order to address and overcome this limitation. METHODS: Head CT images of 108 cases are used. We employ the standardized transformation of statistical parametric mapping 8. The affine transformation parameters are obtained by standardizing the …captured CT images. Automatic MPR processing is performed by using this parameter. The sphenoidal sinus of the orbitomeatal cross section of the automatic MPR processing of this study and the conventional manual MPR processing are cropped with a matrix size of 128×128, and the value of zero mean normalized correlation coefficient is calculated. RESULTS: The computed zero mean normalized cross-correlation coefficient (Rzncc) of≥0.9, 0.8≤Rzncc < 0.9 and 0.7≤Rzncc < 0.8 are achieved in 105 cases (97.2%), 2 cases (1.9%), and 1 case (0.9%), respectively. The average Rzncc was 0.96±0.03. CONCLUSION: Using the proposed new method in this study, MPR processing with guaranteed accuracy is efficiently achieved. Show more

Keywords: Automatic multi planar reconstruction, radiological identification, head computed tomography, forensic radiology, orbitomeatal base line, brain template.

DOI: 10.3233/XST-221142

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 777-788, 2022

Authors: Dong, Tao | Zhang, Huaxia | Wu, Zhifang

Article Type: Research Article

Abstract: BACKGROUND: The detectors of existing large object radiation imaging systems generally work under current-integration mode and cannot distinguish effective signals of unreacted photons from interfering signals of electronic noise and scattered photons, therefore, resulting in image quality deterioration. OBJECTIVE: This study aims to design a new photon-counting mode γ -ray large object radiation imaging system. Therefore, interfering signals with lower energy than effective signals can be eliminated by energy analysis. In addition, the system enables to work properly even under 30∼300Ci Co-60 intensity. METHODS: Based on the physical analysis of the system, the design requirements are …listed. Following the requirements, the best-performing photon-counting detector based on LYSO and SiPM is used in the system. ZP-SK and (ZP)2 -SK filter circuits are designed for Co-60 radiation imaging system with the highest intensity of 100Ci and 300Ci, respectively. Then, a voltage comparator and an FPGA are followed to realize the function of energy analysis and photon counting. RESULTS: The proposed technical solution can improve the Steel Penetration (SP) by at least 60∼70 mmFe compared with the existing current-integration system, which is equivalent to the improvement obtained by increasing the intensity of the radioactive source more than 13 to 20 times. CONCLUSIONS: This study demonstrates the advantages of applying the new photon-counting mode γ -ray large object radiation imaging system to improve the radiation image quality and the penetration ability, which will have enormous potential for future applications. Show more

Keywords: Photon-counting mode, radiation imaging system, electronics circuits, Steel Penetration

DOI: 10.3233/XST-221185

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 789-804, 2022

Authors: Tang, Shaojie | Huang, Tonggang | Qiao, Zhiwei | Li, Baolei | Xu, Yuanfei | Mou, Xuanqin | Fan, Jiulun

Article Type: Research Article

Abstract: Tube of X-ray computed tomography (CT) system emitting a polychromatic spectrum of photons leads to beam hardening artifacts such as cupping and streaks, while the metal implants in the imaged object results in metal artifacts in the reconstructed images. The simultaneous emergence of various beam-hardening artifacts degrades the diagnostic accuracy of CT images in clinics. Thus, it should be deeply investigated for suppressing such artifacts. In this study, data consistency condition is exploited to construct an objective function. Non-convex optimization algorithm is employed to solve the optimal scaling factors. Finally, an optimal bone correction is acquired to simultaneously correct for …cupping, streaks and metal artifacts. Experimental result acquired by a realistic computer simulation demonstrates that the proposed method can adaptively determine the optimal scaling factors, and then correct for various beam-hardening artifacts in the reconstructed CT images. Especially, as compared to the nonlinear least squares before variable substitution, the running time of the new CT image reconstruction algorithm decreases 82.36% and residual error reduces 55.95%. As compared to the nonlinear least squares after variable substitution, the running time of the new algorithm decreases 67.54% with the same residual error. Show more

Keywords: X-ray CT; beam hardening; consistency condition; non-convex optimization

DOI: 10.3233/XST-221176

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 805-822, 2022

Authors: Elshemey, Wael M. | Saif, Refat Abo | Elfiky, Abdo A.

Article Type: Research Article

Abstract: BACKGROUND: Characterization of normal and malignant breast tissues using X-ray scattering techniques has shown promising results and applications. OBJECTIVE: To examine possibility of characterizing normal and malignant breast tissues using the scattered photon distribution of polyenergetic beams of 30 kV X-rays. METHODS: A Monte Carlo simulation is upgraded so that it is capable of simulating input mammographic X-ray spectra from different target-filter combinations, tracing photon transport, and producing the distribution of scattered photons. The target-filter combinations include Mo-Mo, Mo-Al, Mo-Rh, Rh-Rh, Rh-Al, W-Rh, and W-Al. Analysis of obtained scattered photon distribution is carried out by comparing the …ratio of count under the peak in the momentum transfer region from 0 to 1.55 nm–1 , to that in the region from 1.6 to 9.1 nm–1 (covering the regions of scattering from fat and soft tissue, respectively) for breast samples with different percentages of normal tissue (0–100%). RESULTS: Mo-Mo target-filter combination shows a high linear dependence of the count under peak ratio on the percentage of normal tissue in breast samples (R2  = 0.9513). Despite slightly less linear than Mo-Mo, target-filter combinations other than Rh-Rh, W-Rh, and W-Al produce high linear responses (R2  > 0.9) CONCLUSION: Mo-Mo target-filter combination would probably be the most relevant in characterizing normal and malignant breast tissues from their scattered photon distribution. Show more

Keywords: Monte Carlo simulation, breast tissue, X-ray scattering, tissue characterization, mammography

DOI: 10.3233/XST-221154

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 823-834, 2022

Authors: Lin, Liying | Han, Li | Jia, Shaowei | Zhang, Tianyou | Liu, Zefeng | Fan, Jie

Article Type: Research Article

Abstract: BACKGROUND: Blending technology is usually used to improve quality of dual-energy computed (DECT) images. OBJECTIVES: To evaluate the blended DECT image qualities by employing the Blending-Property-Map (BP-Map) and elucidating the optimal parameters with the highest signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). METHODS: Sixty pairs of 80 kV and 140 kV CT images are blended non-linearly by four methods. Protocol A uses the fixed values of blending width (BW) and blending center (BC); Protocol B uses the values of BW =  (CThepatic portal vein – CThepatic parenchymal) / 2 and BC =  (CThepatic portal vein + CThepatic parenchymal) / 2; Protocol C …uses a BW ranging from 10 to 100 HU at an interval of 10 HU and BC = (CThepatic portal vein + CThepatic parenchymal) / 2; Protocol D uses the BP-Map that covers all possible values of BW and BC. RESULTS: When using CT value of adipose tissue as noise, the calculated SNR and CNR of optimal blending width and blending center were 123.22±41.73 and 9.00±3.52, respectively, by the BP-Map in the protocol D. By employing the CT value of back muscle as noise, the SNR and CNR of the best-blended images were 75.90±14.52 and 6.39±2.37, respectively. The subjective score of protocol D was 4.88±0.12. CONCLUSIONS: Compared to traditional blending methods, the BP-Map technique can determine the optimal blending parameter and provide the best-blended images with the highest SNR and CNR. Show more

Keywords: Dual-energy computed tomography (DECT), blending-property-map, image qualities, non-linear blending

DOI: 10.3233/XST-221182

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 835-846, 2022