Journal of X-Ray Science and Technology - Volume Pre-press, issue Pre-press
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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: Prostatic rhabdomyosarcoma (RMS) is a subtype of prostate stromal sarcoma which is rarely reported in adults and usually huge in size. Although there is no consensus on the standard therapy to prostatic RMS, complete resection with negative margin is identified as the best way for maximum survival time. However, to remove a much enlarged prostate completely from a RMS patient is still a very difficult task for a skilled urologist so far. As three-dimension (3D) technology becomes more widely used in medicine, surgeons have the opportunity to challenge previously impossible surgery. In this paper, we reported a 36-year-old male patient…with a 9.6*5.3*7.6 cm prostatic RMS. With the aid of 3D reconstructed video and printing model, the giant tumor was entirely removed without surgery complications and adjacent organs injury. The patient was alive and had no recurrence after 18 months from surgery. This case revealed that 3D reconstruction technology could help in the preoperative assessment and gave benefits to both patients and surgeons.
Abstract: Sparse-view Computed Tomography (CT) has important significance in industrial inspection and medical diagnosis. Mojette transform is a kind of discrete Radon transform that can yield exact reconstructions instead of an approximate solution due to finite Radon sampling. However, the image is iteratively reconstructed pixel by pixel from corner to center, and the image error is proportional to the number of iterations. In this paper, we propose that there exist different sets of projection combinations to recover the original image within the close-to-minimal iterations. And a scheme is given to obtain multiple projection sets, each of which has the same number…of minimum iterations and can recover a CT image with a similar level of small noise but different distributions. These images can be used further to restore the final CT image by counteracting noise with each other. The accuracy and validity of the proposed algorithm are verified by comparison with both other Mojette inversion algorithms and the classical SART algorithm.
Keywords: Radon transform, Mojette transform, close-to-minimal iterations, counteracting-noise, different sets of projection combinations
Abstract: BACKGROUND: SPECT MPI (Single photon emission computed tomography myocardial perfusion imaging) is an essential tool for diagnosis of cardiovascular disease, but it also involves considerable exposure to ionizing radiation. OBJECTIVE: To determine the radioprotective potential of lipoic acid free and nano-capsule against 99m Tc-MIBI-induced injury in cardiovascular tissue. METHODS: The radioprotective ability was assessed by blood count, histopathology and heart enzymes in different groups of mice. Hearts of mice from all groups were dissected and prepared for oxidative stress analysis of superoxide dismutase (SOD) and malondialdehyde (MDA). Furthermore, levels of DNA damage in heart and bone…marrow cells were evaluated by alkaline comet assay technique. The same measurements were estimated after treating the mice with lipoic acid. RESULTS: Comparing mice injected by radiopharmaceutics with control group showed a significant depression in the count of white blood cells (WBC) by about 40 % at 24 &72 hrs post-radiopharmaceutical administration. Moreover, platelets count was decreased by 27% at 72 hrs post-radiopharmaceutical administration. Radiation also dropped in super oxide dismutase (SOD) and increased in activity of heart enzymes and level of MDA (Malondialdehyde). Additionally, histopathological observation was characterized by focal necrosis of cardiac myocytes. 99m Tc-MIBI induced DNA damage had significant increase. Nevertheless, pretreatment with free and lipoic acid nano-capsules (LANC’s) prevented the reduction induced in WBCs and platelets, and improved their counts significantly. Conversely pre-treatment with lipoic acid free and nano-capsule significantly increased the activity of SOD and decreased the level of MDA and therefore protected the cardiovascular tissues and reduced DNA strand-break, consequently and enhanced the body weight of the mice. CONCLUSIONS: These findings highlight the efficacy of lipoic acid free and nano-capsule as a radio protector.
Keywords: Lipoic acid free and nano-capsule, Radioprotection,
99mTc-MIBI, Antioxidant, DNA damage
Abstract: OBJECTIVE: To assess the difference in absorbed organ dose and image quality for head-neck CT angiography using organ dose modulation compared with 3D smart mA modulation in different body mass indices (BMIs) using an adaptive statistical iterative reconstruction (ASiR-V) algorithm. METHODS: Three hundred patients underwent head-neck CTA were equally divided into three groups: A (18.5 kg/m2 ≦BMI < 24.9 kg/m2 ), B (24.9 kg/m2 ≦BMI < 29.9 kg/m2 ) and C (29.9 kg/m2 ≦BMI≦34.9 kg/m2 ). The groups were randomly subdivided into two subgroups (n = 50): A1-A2, B1-B2 and C1-C2. The patients in subgroups A1, B1 and C1 underwent organ dose modulation with the ASiR-V algorithm,…while other patients underwent 3D smart mA modulation. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all head-neck CT angiography images were calculated. Images were then subjectively evaluated. Mean values of several indices including dose-length product (DLP) were computed. The DLP was converted to the effective dose (ED). SNR, CNR and ED in groups A, B, and C were compared in statistical data analysis. RESULTS: SNR, CNR, and subjective image scores show no statistical differences in three groups (P > 0.05). However, there is significant difference of ED values (P < 0.05) . For example, in subgroup A1 mean ED values are 15.30% and 23.66% lower than those in subgroup A2 at thyroid gland and eye lens, respectively. Similar patterns also exist in groups B (B1 vs. B2) and C (C1 vs. C2). CONCLUSIONS: Using organ dose modulation and applying the ASiR-V algorithm can more effectively reduce the radiation dose in head-neck CT angiography than using 3D smart mA modulation, while maintaining image quality. Thus, using organ-based dose modulation has the additional benefit of reducing dose to the thyroid gland and eye lens.
Keywords: Organ dose modulation, 3D smart mA modulation, radiation dose, image quality, head-neck CT angiography
Abstract: BACKGROUND: Due to large dimensional matrix multiplications, the existing iterative algorithms for cone beam computed tomography (CBCT) reconstruction often face problems of heavy computational workload and large volume of memory usage. OBJECTIVE: This study proposes and tests an iterative algorithm of 3DA-TVAL3 for fast reconstruction of CBCT images using undersampled measurement data and the reduced amount of computer memories. METHODS: In order to reduce computational workload and computer memories based on the sparsity of the CBCT measurement matrix, the proposed iterative algorithm applies elementwise scalar multiplications in the iterative computation to search for optimal solution. Through…a number of tests on three different CT data sets with different number of projections, the reconstruction performance of the proposed algorithm is compared with that of two accelerated iterative algorithms and the conventional FDK algorithm. RESULTS: The visual and quantitative evaluations using the normalized mean square error, peak signal to noise ratio and structural similarity metrics demonstrated the faster computational time and the higher image quality of using the proposed 3DA-TVAL3 algorithm than using other conventional algorithms under comparison. CONCLUSIONS: The proposed 3DA-TVAL3 algorithm can perform efficient and fast computation of CBCT reconstruction using the reduced amount of computer memories.
Abstract: BACKGROUND: Computer aided detection (CADe) of pulmonary nodules from computed tomography (CT) is crucial for early diagnosis of lung cancer. Self-learned features obtained by training datasets via deep learning have facilitated CADe of the nodules. However, the complexity of CT lung images renders a challenge of extracting effective features by self-learning only. This condition is exacerbated for limited size of datasets. On the other hand, the engineered features have been widely studied. OBJECTIVE: We proposed a novel nodule CADe which aims to relieve the challenge by the use of available engineered features to prevent convolution neural networks (CNN)…from overfitting under dataset limitation and reduce the running-time complexity of self-learning. METHODS: The CADe methodology infuses adequately the engineered features, particularly texture features, into the deep learning process. RESULTS: The methodology was validated on 208 patients with at least one juxta-pleural nodule from the public LIDC-IDRI database. Results demonstrated that the methodology achieves a sensitivity of 88% with 1.9 false positives per scan and a sensitivity of 94.01% with 4.01 false positives per scan. CONCLUSIONS: The methodology shows high performance compared with the state-of-the-art results, in terms of accuracy and efficiency, from both existing CNN-based approaches and engineered feature-based classifications.
Keywords: Computer aided detection (CADe), computed tomography (CT) imaging, pulmonary nodules, deep learning, image features analysis
Abstract: BACKGROUND: Improved visualization of lung cancer-associated vessels is vital. OBJECTIVE: To evaluate the efficacy of 3-D quantitative CT in lung cancer-associated pulmonary vessel assessment. METHODS: Vascular CT changes were assessed visually and using FACT-Digital lung TM software (n = 162 patients, 178 controls). The total number of pulmonary vessels (TNV) and mean lumen area of pulmonary vessels (MAV) vertical to cross-sections of fifth/sixth-generation bronchioles were measured. RESULTS: Visual investigation revealed fewer ipsilateral pulmonary vascular abnormalities in lung cancer (151/162) than did quantitative CT (162/162), and required more time (3.2±1.5 vs. 2.5±1.3 min) (P < 0.05). CT…measurements revealed that the TNV vertical to the fifth-generation bronchial cross-section of the ipsilateral, contralateral, and control groups was 14.58±4.75, 9.58±3.74, and 10.22±4.07 and the MAV in these groups was 99.70±26.20, 58.76±29.29, and 57.76±18.32, respectively. The TNV vertical to the sixth-generation bronchial cross-section of the ipsilateral, contralateral, and control groups was 16.64±5.14, 11.59±4.06, and 11.75±4.16 and the MAV was 110.22±31.47, 67.62±30.41, and 60.24±16.18, respectively. The TNV and MAV in ipsilateral lung cancer tissues exceeded those in the contralateral side and control group tissues (P < 0.001). CONCLUSIONS: Automated 3-D quantitative CT could successfully characterize pulmonary vessels and their lung cancer-associated changes.
Keywords: Lung cancer, CT, total number of vessels, mean lumen area of vessels, quantitative measurement
Abstract: In this study, we designed mobile X-ray equipment that generates high-power X-rays, using an internal power source by means of a super-capacitor, and evaluated its safety. The proposed X-ray equipment uses the charging voltage of a battery to store high density energy, supplementing the electric charge of the super-capacitor, which can instantly release a large amount of energy. Further, pulse frequency modulation was applied to produce high voltage and thereby improve energy efficiency. The developed mobile X-ray equipment enables to generate an output of 30 kW and, therefore, can be applied to many diagnostic fields. In addition, various devices and control…circuits were employed to ensure convenience and safety of using the equipment in clinical applications. This study analyzed the error ranges regarding tube voltage, tube current, irradiation time, coefficient variation, half-value layer, and the output characteristics. The results showed that the proposed X-ray equipment was able to generate 80mR X-ray power under the condition of 30 kW. The coefficient variation was less than 0.05 at all measurement points, which indicates that it is possible to generate the equal amount of X-ray when the driving conditions are same. Results also showed 51.25% of transmittance at 3.5mmAL in the case of the wire, which is thicker than a common reference of 2.3mmAL and indicates that this new mobile equipment is possible to generate X-rays with relatively high permeability. In conclusion, the findings in this study suggest that the new equipment can generate consistent high-power X-rays and, therefore, can be used safely by minimizing unnecessary re-taking of images and radiation exposure.
Keywords: Mobile X-ray, super-capacitor, coefficient variation, half-value layer
Abstract: BACKGROUND: Some patients cannot be imaged with cone-beam CT for image-guided radiation therapy because their size, pose, or fixation devices cause collisions with the machine. OBJECTIVE: To investigate imaging trajectories that avoid such collisions by using virtual isocenter and variable magnification during acquisition while yielding comparable image quality. METHODS: The machine components most likely to collide are the gantry and kV detector. A virtual isocenter trajectory continuously moves the patient during gantry rotation to maintain an increased separation between the two. With dynamic magnification, the kV detector is dynamically moved to increase clearance for an angular…range around the potential collision point while acquiring sufficient data to maintain the field-of-view. Both strategies were used independently and jointly with the resultant image quality evaluated against the standard circular acquisition. RESULTS: Collision avoiding trajectories show comparable contrast and resolution to standard techniques. For an anthropomorphic phantom, the RMSE is <7×10- 4 , multi-scale structural similarity index is >0.97, and visual image fidelity is >0.96 for all trajectories when compared to a standard circular scan. CONCLUSIONS: The proposed trajectories avoid machine-patient collisions while providing comparable image quality to the current standard thereby enabling CBCT imaging for patients that could not otherwise be scanned.
Abstract: Performing X-ray computed tomography (CT) examinations with less radiation has recently received increasing interest: in medical imaging this means less (potentially harmful) radiation for the patient; in non-destructive testing of materials/objects such as testing jet engines, the reduction of the number of projection angles (which for large objects is in general high) leads to a substantial decreasing of the experiment time. In the experiment, less radiation is usually achieved by either (1) reducing the radiation dose used at each projection angle or (2) using sparse view X-ray CT, which means significantly less projection angles are used during the examination. In…this work, we study the performance of the recently proposed sinogram-based iterative reconstruction algorithm in sparse view X-ray CT and show that it provides, in some cases, reconstruction accuracy better than that obtained by some of the Total Variation regularization techniques. The provided accuracy is obtained with computation times comparable to other techniques. An important feature of the sinogram-based iterative reconstruction algorithm is that it is simpler and without the many parameters specific to other techniques.