Journal of X-Ray Science and Technology - Volume 24, 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: This study aims to investigate whether integration of traditional Chinese medicine and modern medicine has advantage in achieving the improved diagnosis and treatment of knee osteoarthritis. METHODS: 90 patients with knee osteoarthritis were selected from The Department of Minimal Invasive Joint of The Third Affiliated Hospital of Beijing University of Chinese Medicine from June 2013 to June 2015. They were divided into 3 groups with 30 cases per group in accordance to the syndrome differentiation of traditional Chinese medicine. The patients underwent arthroscopic surgery, and we categorized the patients having the same characterization in each group,…and those having distinct difference into the three groups. Based on the arthroscopic analysis, we performed analysis of statistical data in order to analyze the relation between knee osteoarthritis under arthroscope and traditional Chinese medicine syndromes. RESULTS: There are three syndromes according to traditional Chinese medicine that can be categorized into various different groups. The synovial proliferation can be seen mostly in the syndrome of stagnation of blood stasis. The slight damage of knee joint cartilage can be seen in the syndrome of yang deficiency and cold stagnation, the severe one in the syndrome of kidney-marrow deficiency. We found that there are different pathological expressions with the various degree of the tissues damage at the knee and we categorized the knee according to their syndrome. CONCLUSION: For knee osteoarthritis, different syndromes of traditional Chinese medicine presents different tissues pathological changes at the knee joint under arthroscopy, which will provide objective basis for the diagnosis of this medical condition.
Keywords: Knee osteoarthritis, arthroscopic surgery, traditional Chinese medicine syndromes, orthopedic diagnosis
Abstract: PURPOSE: This study aimed to investigate the feasibility of efficiently using a rigid image registration (RIR) algorithm or a deformable image registration (DIR) algorithm to match medical images and evaluate the impact of setup errors on intensity modulated radiation therapy of lung cancer patients. METHODS: Ten lung cancer patients were chosen randomly each day and were subjected to image-guided radiotherapy. The clinical registration between cone-beam computed tomography (CBCT) images and treatment planning system CT images was performed by applying both RIR and DIR; the clinical registration was evaluated on the basis of the contour index, including dice…similarity coefficient, sensitivity, and positive predictive value; the optimal scheme of image registration was selected to ensure that the actual irradiation isocenter was consistent with the treatment planning isocenter. In each patient, the translational errors in the right-left (x), superior-inferior (y), and anterior-posterior (z) directions and the rotational errors in the u, υ , and w directions formed by the x, y, and z directions were calculated and analyzed daily in the whole course of treatment; margins were calculated according to this equation: M = 2.5∑+ 0.7δ . RESULTS: The tumors and the surrounding soft tissues of the patients are shown more clearly in the CBCT images than in the CT images. DIR can be applied more efficiently than RIR to determine the morphological and positional changes in the organs shown in the images with the same or different modalities in the different period. The setup errors in translation in the x, y and z axes were 0.05±0.16, 0.09±0.32 and –0.02±0.13 cm, respectively; by contrast, the setup errors in rotation in u, υ and w directions were (0.41±0.64)°, (–0.08±0.57)° and (–0.03±0.62)°, respectively. The setup errors in the x, y and z axes of the patients indicated that the margins expansions were 0.82, 1.15 and 0.72 cm, respectively. CONCLUSION: CBCT with DIR can measure and correct the setup errors online; as a result, setup errors in lung cancer treatments can be significantly reduced and the accuracy of radiotherapy can be enhanced.
Abstract: OBJECTIVE: This study aims to investigate the value of PET/CT scanning in preoperative diagnosis of cervical carcinoma, especially for detecting lymph node metastasis. MATERIALS AND METHODS: The approval of the ethics committee which was granted by our hospital was obtained beforehand. Patients with CC were collected into this investigation between January 2011 and October 2015. Each participant received surgeries, as well as pelvic and paraaortic systematic lymph node dissection. After operations, CC types were confirmed by pathological examinations. The tumor stages were assessed by 3 experienced radiologists independently, according to FIGO examinations and positron emission tomography-computed tomography…(PET/CT), and these above diagnostic results were compared with postoperative biopsy pathology, respectively. Statistical analysis was done by SPSS 16.0, and the diagnostic performance of PET/CT was calculated. RESULTS: 51 patients were identified in this investigation, and the mean age of these female individuals was 42.3±6.7 years (range, 34–58 years). Depending on statistical analysis, the staging accuracy of PET/CT to detect primary tumors was 84.31%, with sensitivity 88.00% and specificity 80.77%. With respect to lymph nodes, the accuracy could reach 76.47%, with sensitivity 82.61% and specificity 71.43%. On the other hand, FIGO staging performed poorly in detecting primary tumors, with sensitivity 44.12%, specificity 47.06% and accuracy 45.10%. In terms of testing lymph nodes, the diagnosis parameters were as followed, sensitivity 28.57%, specificity 8.70% and accuracy 19.61%. After statistical analysis, there was significantly different between two methods (P < 0.05). CONCLUSIONS: PET/CT scanning may be valuable in detecting primary tumors and lymph nodes, and more accurate staging may lead to improving therapeutic planning in CC patients.
Keywords: Diagnosis, positron emission tomography-computed tomography, cervical cancer
Abstract: Data sets containing colored anatomical images of the human body, such as Visible Human or Visible Korean, show realistic internal organ structures. However, imperfect segmentations of these color images, which are typically generated manually or semi-automatically, produces poor-quality rendering results. We propose an interactive high-quality visualization method using GPU-based refinements to aid in the study of anatomical structures. In order to represent the boundaries of a region-of-interest (ROI) smoothly, we apply Gaussian filtering to the opacity values of the color volume. Morphological grayscale erosion operations are performed to reduce the region size, which is expanded by Gaussian filtering. Pseudo-coloring and…color blending are also applied to the color volume in order to give more informative rendering results. We implement these operations on GPUs to speed up the refinements. As a result, our method delivered high-quality result images with smooth boundaries and provided considerably faster refinements. The speed of these refinements is sufficient to be used with interactive renderings as the ROI changes, especially compared to CPU-based methods. Moreover, the pseudo-coloring methods used presented anatomical structures clearly.
Keywords: Color volume rendering, color human body, Gaussian filtering, morphology operations, pseudo-coloring, GPU-based refinement
Abstract: BACKGROUND: The relatively high radiation dose from micro-CT is a cause for concern in preclinical research involving animal subjects. Interior region-of-interest (ROI) imaging was proposed for dose reduction, but has not been experimentally applied in micro-CT. OBJECTIVE: Our aim is to implement interior ROI imaging in a carbon nanotube (CNT) x-ray source based micro-CT, and present the ROI image quality and radiation dose reduction for interior cardiac micro-CT imaging of a mouse heart in situ . METHODS: An aperture collimator was mounted at the source-side to induce a small-sized cone beam (10 mm width) at the…isocenter. Interior in situ micro-CT scans were conducted on a mouse carcass and several micro-CT phantoms. A GPU-accelerated hybrid iterative reconstruction algorithm was employed for volumetric image reconstruction. Radiation dose was measured for the same system operated at the interior and global micro-CT modes. RESULTS: Visual inspection demonstrated comparable image quality between two scan modes. Quantitative evaluation demonstrated high structural similarity index (up to 0.9614) with improved contrast-noise-ratio (CNR) on interior micro-CT mode. Interior micro-CT mode yielded significant reduction (up to 83.9%) for dose length product (DLP). CONCLUSIONS: This work demonstrates the applicability of using CNT x-ray source based interior micro-CT for preclinical imaging with significantly reduced radiation dose.
Abstract: In vivo range verification methods will reveal information about the penetration depth into a patient for an incident proton beam. The prompt gamma (PG) method is a promising in vivo technique that has been shown to yield this range information by measuring the escaping MeV photons given a suitable detector system. The majority of current simulations investigating PG detectors utilize common scintillating materials ideal for photons within a low neutron background radiation field using complex geometries or novel designs. In this work we simulate a minimal detector system using a material ideal for MeV photon detection in the…presence of a significant neutron field based on the Cherenkov phenomenon. The response of this selected material was quantified for the escaping particles commonly found in proton therapy applications and the feasibility of using the PG technique for this detector material was studied. Our simulations found that the majority of the range information can be determined by detecting photons emitted with a timing window less than ∼50 ns after the interaction of the proton beam with the water phantom and with an energy threshold focusing on the energy range of the de-excitation of 16 O photons (∼6 MeV). The Cherenkov material investigated is able to collect these photons and estimate the range with timescales on the order of tens of nanoseconds as well as greatly suppress the signal due to neutron.
Keywords: Proton therapy, GEANT4, Monte Carlo, Cherenkov, prompt gamma
Abstract: BACKGROUND: In computed tomography (CT), the spot geometry is one of the main sources of error in CT images. Since X-rays do not arise from a point source, artefacts are produced. In particular there is a penumbra effect, leading to poorly defined edges within a reconstructed volume. Penumbra models can be simulated given a fixed spot geometry and the known experimental setup. OBJECTIVE: This paper proposes to use a penumbra model, derived from Beer’s law, both to confirm spot geometry from penumbra data, and to quantify blurring in the image. METHODS: Two models for the…spot geometry are considered; one consists of a single Gaussian spot, the other is a mixture model consisting of a Gaussian spot together with a larger uniform spot. RESULTS: The model consisting of a single Gaussian spot has a poor fit at the boundary. The mixture model (which adds a larger uniform spot) exhibits a much improved fit. The parameters corresponding to the uniform spot are similar across all powers, and further experiments suggest that the uniform spot produces only soft X-rays of relatively low-energy. CONCLUSIONS: Thus, the precision of radiographs can be estimated from the penumbra effect in the image. The use of a thin copper filter reduces the size of the effective penumbra.
Abstract: PURPOSE: A motion algorithm has been developed to extract length, CT number level and motion amplitude of a mobile target from cone-beam CT (CBCT) images. MATERIALS AND METHODS: The algorithm uses three measurable parameters: Apparent length and blurred CT number distribution of a mobile target obtained from CBCT images to determine length, CT-number value of the stationary target, and motion amplitude. The predictions of this algorithm are tested with mobile targets having different well-known sizes that are made from tissue-equivalent gel which is inserted into a thorax phantom. The phantom moves sinusoidally in one-direction to simulate respiratory…motion using eight amplitudes ranging 0–20 mm. RESULTS: Using this motion algorithm, three unknown parameters are extracted that include: Length of the target, CT number level, speed or motion amplitude for the mobile targets from CBCT images. The motion algorithm solves for the three unknown parameters using measured length, CT number level and gradient for a well-defined mobile target obtained from CBCT images. The motion model agrees with the measured lengths which are dependent on the target length and motion amplitude. The gradient of the CT number distribution of the mobile target is dependent on the stationary CT number level, the target length and motion amplitude. Motion frequency and phase do not affect the elongation and CT number distribution of the mobile target and could not be determined. CONCLUSION: A motion algorithm has been developed to extract three parameters that include length, CT number level and motion amplitude or speed of mobile targets directly from reconstructed CBCT images without prior knowledge of the stationary target parameters. This algorithm provides alternative to 4D-CBCT without requirement of motion tracking and sorting of the images into different breathing phases. The motion model developed here works well for tumors that have simple shapes, high contrast relative to surrounding tissues and move nearly in regular motion pattern that can be approximated with a simple sinusoidal function. This algorithm has potential applications in diagnostic CT imaging and radiotherapy in terms of motion management.
Keywords: Motion algorithm, 4D-cone-beam CT, motion parameters, physical parameters, target elongation, CT number distribution
Abstract: To reduce the radiation dose and the equipment cost associated with lung CT screening, in this paper we propose a mixed reality based nodule measurement method with an active shutter stereo imaging system. Without involving hundreds of projection views and subsequent image reconstruction, we generated two projections of an iteratively placed ellipsoidal volume in the field of view and merging these synthetic projections with two original CT projections. We then demonstrated the feasibility of measuring the position and size of a nodule by observing whether projections of an ellipsoidal volume and the nodule are overlapped from a human observer’s visual…perception through the active shutter 3D vision glasses. The average errors of measured nodule parameters are less than 1 mm in the simulated experiment with 8 viewers. Hence, it could measure real nodules accurately in the experiments with physically measured projections.
Abstract: BACKGROUND: Decreasing the number of projections is an effective way to reduce the radiation dose exposed to patients in medical computed tomography (CT) imaging. However, incomplete projection data for CT reconstruction will result in artifacts and distortions. OBJECTIVE: In this paper, a novel dictionary learning algorithm operating in the gradient-domain (Grad-DL) is proposed for few-view CT reconstruction. Specifically, the dictionaries are trained from the horizontal and vertical gradient images, respectively and the desired image is reconstructed subsequently from the sparse representations of both gradients by solving the least-square method. METHODS: Since the gradient images are…sparser than the image itself, the proposed approach could lead to sparser representations than conventional DL methods in the image-domain, and thus a better reconstruction quality is achieved. RESULTS: To evaluate the proposed Grad-DL algorithm, both qualitative and quantitative studies were employed through computer simulations as well as real data experiments on fan-beam and cone-beam geometry. CONCLUSIONS: The results show that the proposed algorithm can yield better images than the existing algorithms.