Journal of X-Ray Science and Technology - Volume 27, issue 4
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Journal of X-Ray Science and Technology is an international journal designed for the diverse community (biomedical, industrial and academic) of users and developers of novel x-ray imaging techniques. The purpose of the journal is to provide clear and full coverage of new developments and applications in the field.
Areas such as x-ray microlithography, x-ray astronomy and medical x-ray imaging as well as new technologies arising from fields traditionally considered unrelated to x rays (semiconductor processing, accelerator technology, ionizing and non-ionizing medical diagnostic and therapeutic modalities, etc.) present opportunities for research that can meet new challenges as they arise.
Abstract: OBJECTIVE: Identification of interstitial lung disease (ILD) may be difficult in certain cases using pulmonary function tests (PFTs) or subjective radiological analysis. We evaluated the efficacy of quantitative computed tomography (CT) with 3-dimensional (3D) reconstruction for distinguishing ILD patients from healthy controls. MATERIALS AND METHODS: We retrospectively collected chest CT images of 102 ILD patients and 102 healthy matched controls, and measured the following parameters: lung parenchymal volume, emphysema indices low attenuation area LAA910 volume, LAA950 volume, LAA910%, and LAA950%, and mean lung density (MLD) for whole lung, left lung, right lung, and each lobe, respectively. The Mann-Whitney…U test was used to compare quantitative CT parameters between groups. Receiver operating characteristic (ROC) curves, Bayesian stepwise discriminant analysis, and deep neural network analysis were used to test the discriminative performance of quantitative CT parameters. Binary logistic regression was performed to identify ILD markers. RESULTS: Total lung volume was lower in ILD patients than controls, while emphysema and MLD values were higher (P < 0.001) except LAA910 volume in right middle lobe. LAA910 volume, LAA950 volume, LAA910%, LAA950%, and MLD accurately distinguished ILD patients from healthy controls (AUC >0.5, P < 0.05), and high MLD was a significant marker for ILD (OR = 1.047, P < 0.05). CONCLUSIONS: This quantitative CT analysis can effectively identify ILD patients, providing an alternative to subjective image analysis and PFTs.
Keywords: Interstitial lung diseases, computer-aided CT quantification, mean lung density
Abstract: OBJECTIVE: To investigate and evaluate the accuracy of ultrasound (US) imaging for measurement of ischiofemoral space (IFS) compared with magnetic resonance imaging (MRI). METHODS: Twenty-five hips of 16 patients with hip pain and ipsilateral quadratus femoris muscle (QFM) edema were recruited to the IFI group, and 19 hips of 19 patients without hip pain and QFM edema were recruited as the control group. IFS of both groups was measured by US and MRI. The correlations and differences between US and MRI measurements were then assessed. Last, the receiver operating characteristic (ROC) data analysis was performed. RESULTS:…The US results revealed a decreased IFS in IFI hips compared with controls (P < 0.001), suggesting that US were valuable in identifying IFI. IFS measured by US and MRI showed positive correlations in both the IFI group (r = 0.409, P = 0.042) and control group (r = 0.575, P = 0.01). There were no statistically significant differences between IFS measured by US and MRI in the control group (P = 0.657), while IFS measurements in the IFI group performed with US were significantly greater than those with MRI (P < 0.001). ROC curve analysis revealed that the cutoff value of IFS measured with US was 2.14 cm, with a sensitivity of 92.0% and specificity of 68.4%, while measured by MRI was 1.87 cm, with a sensitivity of 96.0% and specificity of 84.2%. CONCLUSIONS: IFS measurements obtained with US are very similar to those obtained with MRI. Therefore, US provides a low-cost and easy-to-operate alternative imaging modality to measure IFS.
Keywords: Ishiofemoral, impingement, ultrasound, magnetic resonance images
Abstract: BACKGROUND: Deep learning has made spectacular achievements in analysing natural images, but it faces challenges for medical applications partly due to inadequate images. OBJECTIVE: Aiming to classify malignant and benign pulmonary nodules using CT images, we explore different strategies to utilize the state-of-the-art deep convolutional neural networks (CNN). METHODS: Experiments are conducted using the Lung Image Database Consortium image collection (LIDC-IDRI), which is a public database containing 1018 cases. Three strategies are implemented including to 1) modify some state-of-the-art CNN architectures, 2) integrate different CNNs and 3) adopt transfer learning. Totally, 11 deep CNN models are…compared using the same dataset. RESULTS: Study demonstrates that, for the model modification scheme, a concise CifarNet performs better than the other modified CNNs with more complex architectures, achieving an area under ROC curve of AUC = 0.90. Integrated CNN models do not significantly improve the classification performance, but the model complexity is reduced. Transfer learning outperforms the other two schemes and ResNet with fine-tuning leads to the best performance with an AUC = 0.94, as well as the sensitivity of 91% and an overall accuracy of 88%. CONCLUSIONS: Model modification, model integration, and transfer learning can play important roles to identify and generate optimal deep CNN models in classifying pulmonary nodules based on CT images efficiently. Transfer learning is preferred when applying deep learning to medical imaging applications.
Keywords: Convolutional neural networks, deep learning, lung cancer, nodule classification, transfer learning
Abstract: There are several factors that may contribute to the increase in radiation dose of CT including the use of unoptimized protocols and improper scanning technique. In this study, we aim to determine significant impact on radiation dose as a result of mis-centering during CT head examination. The scanning was performed by using Toshiba Aquilion 64 slices multi-detector CT (MDCT) scanner and dose were measured by using calibrated ionization chamber. Two scanning protocols of routine CT head; 120 kVp/ 180 mAs and 100 kVp/ 142 mAs were used represent standard and low dose, respectively. As reference measurement, the dose was first…measured on standard cylindrical polymethyl methacrylate (PMMA) phantom that positioned at 104 cm from the floor (reference isocenter). The positions then were varied to simulate mis-centering by 5 cm from isocenter, superiorly and inferiorly at 109 cm, 114 cm, 119 cm, 124 cm and 99 cm, 94 cm, 89 cm, 84 cm, respectively. Scanning parameter and dose information from the console were recorded for the radiation effective dose (E) measurement. The highest mean CTDIvol value for MCS and MCI were 105.06 mGy (at +10 cm) and 105.51 mGy (at – 10 cm), respectively which differed significantly (p < 0.05) as compared to the isocenter. There were large significant different (p < 0.05) of mean Dose Length Product (DLP) recorded between isocenter to the MCS (85.8 mGy.cm) and MCI (93.1 mGy.cm). As the low dose protocol implemented, the volume CTDI (CTDIvol ) were significantly increase (p < 0.05) for MCS (at +10 cm) and MCI (at – 10 cm) when compared to the isocenter. The phantom study revealed a noticeable different in radiation dose between isocenter and experimental groups due to degradation of the bowtie filter performance. It is anticipated that these noteworthy findings may emphasize the importance of accurate patient centering at the isocenter of CT gantry, so that CT optimization practice can be achieved.
Keywords: Mis-centering position, CT head, radiation dose, CT dose index
Abstract: BACKGROUND Quantitative measurement of bronchial morphological changes in pulmonary contusion with acute respiratory distress syndrome (ARDS) has important clinical implications. OBJECTIVE To investigate the morphological changes in bronchus before and after treatment in patients with pulmonary contusion combined with ARDS using an automated bronchial three-dimensional computed tomography (3D-CT) measurement method. METHODS The study involves a dataset of CT images of 62 patients diagnosed with pulmonary contusion combined with ARDS. The volume of pulmonary contusion lesions was calculated as a percentage of the total lung volume using the automated 3D-CT method. The bronchial luminal cross-sectional area, wall…cross-sectional area, the maximum and average wall thickness, the maximum and average luminal densities, intraluminal and extraluminal diameters, and circumferences of generations 2–4 bronchi before and after treatment were measured. Furthermore, the corresponding differences were analyzed statistically. RESULTS The luminal cross-sectional area, wall cross-sectional area, intraluminal and extraluminal diameters, and circumferences of generations 2–4 bronchi were all significantly lower before treatment than after treatment (P < 0.05). However, the maximum and average wall thicknesses were both significantly higher before treatment than after treatment (P < 0.05). No significant difference was found in the maximum and average luminal densities before and after treatment (P > 0.05). The percentage of the pulmonary contusion lesion volume to the total lung volume correlated positively with the thoracic trauma severity score (r = 0.74, P < 0.01). CONCLUSIONS Quantitative bronchial CT image analysis enables to detect and assess bronchial morphological changes in patients diagnosed with pulmonary contusion combined with ARDS.
Keywords: CT quantification for pulmonary contusion, acute respiratory distress syndrome (ARDS), pulmonary contusion combined with ARDS, Bronchial morphological changes in pulmonary contusion
Abstract: The objective of this study is to analyze small field photon beams acquired with commonly available detectors. Beam profiles of 6 MV photons from the Siemens Primus Linear Accelerator were measured with a micro ion chamber (IC CC01, IBA) and linear diode array (LDA-99SC, IBA). Data was acquired using a water phantom for small fields (0.5×0.5 cm2 to 4×4 cm2 ) at depth of maximum dose, 5 cm and 10 cm. Profiles were also generated with EGSnrc Monte Carlo code. Measured and simulated profiles were compared in terms of percentage difference of the area under the simulated and measured profiles (PD…), ratio of the measured to simulated dose at the point of maximum deviation within the central region of profile (R ), full width half maximum (FWHM ) and penumbra. For field sizes ≥1×1 cm2 , the maximum PD is 3.17 % and 2.87 % for IC and LDA respectively, whereas R is in the range of 0.95–1.05 for IC and 0.99–1.05 for LDA. LDA measured FWHM and penumbra are also in better agreement with the simulated results. This study demonstrated that LDA can be used for acquisition of beam profiles for field size as low as 1×1 cm2 .
Keywords: Small field, dosimetry, beam profiles, monte carlo, 6 MV X-ray
Abstract: Multi-source computed tomography (CT) imaging has unique technical advantages not only for dynamic objects, but also for large-size objects by designing its imaging scan mode. Using the triple-source fan-beam imaging scan mode under three circular trajectories with two different radii, we in this study developed and analyzed theoretically several exact reconstruction algorithms in terms of full-scan and short-scan for three sets of truncated projection data. This triple-source scan configuration in different radii cases is easier to be simulated by a single-source scan configuration in an industrial CT system. The proposed algorithms are based on the idea of filtering-back-projection (FBP) algorithm,…and can reconstruct the large-size objects under the same CT devices. The developed algorithms avoid data rebinning and can provide exact and fast image reconstruction. The results of the numerical simulation based data analysis verified that new algorithms were accurate and effective.
Abstract: BACKGROUND: Automatic detection of tumor in breast ultrasound (BUS) images is important for the subsequent image processing and has been researched for decades. However, there still lacks a robust method due to poor quality of BUS images. OBJECTIVE: To propose and test a salient object detection method for BUS images. METHODS: BUS image is preprocessed by an adaptively selective replacement and speckle reducing anisotropic diffusion (SRAD) algorithm. Then, the preprocessed image is segmented into super pixels by a simple linear iterative clustering (SLIC) algorithm to form a graph model, and the saliency of the nodes in…the graph is calculated by using the absorbed time of absorbing Markov chain (AMC). Finally, the initial saliency map is optimized by the recurrent time of ergodic Markov chain (EMC) and a distance weighting formula. RESULTS: Results of the proposed method were compared both qualitatively and quantitatively with two saliency detection models. It was observed that the proposed method outperformed the comparison models and yielded the highest Accuracy value (97.49% vs. 86.63% and 90.33%) using a dataset of 1000 BUS images. CONCLUSIONS: After the adaptively selective replacement, AMC can effectively distinguish tumors from background by random walks.
Abstract: OBJECTIVE: The skin marking method (SMM) and bow-form-ruler marking method (BFRM) are two commonly used patient marking methods in mainland China. This study aims to evaluate SMM and BFRM by comparing the inter-fraction setup errors from using these two methods together with vacuum cushion immobilization in patients underwent radiotherapy for different treatment sites. MATERIALS AND METHODS: Eighteen patients diagnosed with pelvic, abdominal and thoracic malignant tumors (with 6 patients per treatment site) were enrolled in this prospective study. All patients were immobilized with vacuum cushion. Each patient was marked by both SMM and BFRM before computed tomography (CT)…simulation. Target location was verified by cone beam CT images with displacements assessed prior to each sampled treatment session. The localization errors in three translational and three rotational directions were recorded and analyzed. RESULTS: Images from 108 fractions in 18 patients produced 324 translational and 324 rotational comparisons for SMM and BFRM. The setup errors of all treatment sites showed no difference in two marking methods in any directions (p > 0.05). In subgroups of treatment site analysis, SMM significantly lessened the lateral and yaw setup errors compared to BFRM in the pelvic sites (0.39±1.85 mm vs –1.28±1.13 mm, p < 0.01 and –0.19±0.59° vs –0.61±0.59°, p < 0.05). However, in the abdominal subgroup, BFRM was superior to SMM for reduced vertical errors (0.17±2.73 mm vs 2.28±3.16 mm, p < 0.05). For the underweight or obese patients (with Body Mass Index, BMI < 18.5 or BMI≥24), SMM resulted in less yaw errors compared to BFRM (–0.05±0.38° vs –0.43±0.48°, p < 0.05). No significant difference between SMM and BFRM in setup errors of normal weighted patients (18.5≤BMI < 24) was observed for all three studied treatment sites. CONCLUSIONS: This study shows no significant difference in patient setup errors for various treatment sites between SMM and BFRM in general. SMM may be suitable for the pelvic tumor and patients with BMI < 18.5 or BMI≥24, while BFRM is recommended for the abdominal tumor sites.
Abstract: PURPOSE: This study evaluates the feasibility of our previously developed Respiratory Motion Compensation System (RMCS) combined with the Phase Lead Compensator (PLC) to eliminate system delays during the compensation of respiration-induced tumor motion. The study objective is to improve the compensation effect of RMCS and the efficay of radiation therapy to reduce its side effects to the patients. MATERIAL AND METHODS: In this study, LabVIEW was used to develop the proposed software for calculating real-time adaptive control parameters, combined with PLC and RMCS for the compensation of total system delay time. Experiments of respiratory motion compensation were performed…using 6 pre-recorded human respiration patterns and 7 sets of different sine waves. During the experiments, a respiratory simulation device, Respiratory Motion Simulation System (RMSS), was placed on the RMCS, and the detected target motion signals by the Ultrasound Image Tracking Algorithm (UITA) were transmitted to the RMCS, and the compensation of respiration induced motion was started. Finally, the tracking error of the system is obtained by comparing the encoder signals bwtween RMSS and RMCS. The compensation efficacy is verified by the root mean squared error (RMSE) and the system compensation rate (CR). RESULTS: The experimental results show that the calcuated CR with the simulated respiration patterns is between 42.85% ∼3.53% and 33.76% ∼2.62% in the Right-Left (RL) and Superior-Inferior (SI), respectively, after the RMCS compensation of using the adaptive control parameters in PLC. For the compensation results of human respiration patterns, the CR is between 58.95% ∼8.56% and 62.87% ∼9.05% in RL and SI, respectively. CONCLUSIONS: During the respiratory motion compensation, the influence of the delay time of the entire system (RMCS+RMSS+UITA) on the compensation effect was improved by adding an adaptive control PLC, which reduces compensation error and helps improve efficacy of radiation therapy.
Keywords: Real-time adaptive control parameters, respiratory motion compensation, ultrasound image tracking, organ motion correction