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Sample records for low-dose unenhanced ct

  1. Adaptively Tuned Iterative Low Dose CT Image Denoising

    PubMed Central

    Hashemi, SayedMasoud; Paul, Narinder S.; Beheshti, Soosan; Cobbold, Richard S. C.

    2015-01-01

    Improving image quality is a critical objective in low dose computed tomography (CT) imaging and is the primary focus of CT image denoising. State-of-the-art CT denoising algorithms are mainly based on iterative minimization of an objective function, in which the performance is controlled by regularization parameters. To achieve the best results, these should be chosen carefully. However, the parameter selection is typically performed in an ad hoc manner, which can cause the algorithms to converge slowly or become trapped in a local minimum. To overcome these issues a noise confidence region evaluation (NCRE) method is used, which evaluates the denoising residuals iteratively and compares their statistics with those produced by additive noise. It then updates the parameters at the end of each iteration to achieve a better match to the noise statistics. By combining NCRE with the fundamentals of block matching and 3D filtering (BM3D) approach, a new iterative CT image denoising method is proposed. It is shown that this new denoising method improves the BM3D performance in terms of both the mean square error and a structural similarity index. Moreover, simulations and patient results show that this method preserves the clinically important details of low dose CT images together with a substantial noise reduction. PMID:26089972

  2. Low dose CT perfusion using k-means clustering

    NASA Astrophysics Data System (ADS)

    Pisana, Francesco; Henzler, Thomas; Schönberg, Stefan; Klotz, Ernst; Schmidt, Bernhard; Kachelrieß, Marc

    2016-03-01

    We aim at improving low dose CT perfusion functional parameters maps and CT images quality, preserving quantitative information. In a dynamic CT perfusion dataset, each voxel is measured T times, where T is the number of acquired time points. In this sense, we can think about a voxel as a point in a T-dimensional space, where the coordinates of the voxels would be the values of its time attenuation curve (TAC). Starting from this idea, a k-means algorithm was designed to group voxels in K classes. A modified guided time-intensity profile similarity (gTIPS) filter was implemented and applied only for those voxels belonging to the same class. The approach was tested on a digital brain perfusion phantom as well as on clinical brain and body perfusion datasets, and compared to the original TIPS implementation. The TIPS filter showed the highest CNR improvement, but lowest spatial resolution. gTIPS proved to have the best combination of spatial resolution and CNR improvement for CT images, while k-gTIPS was superior to both gTIPS and TIPS in terms of perfusion maps image quality. We demonstrate k-means clustering analysis can be applied to denoise dynamic CT perfusion data and to improve functional maps. Beside the promising results, this approach has the major benefit of being independent from the perfusion model employed for functional parameters calculation. No similar approaches were found in literature.

  3. Low-dose CT of the lungs: Preliminary observations

    SciTech Connect

    Naidich, D.P.; Marshall, C.H.; Gribbin, C.; Arams, R.S.; McCauley, D.I. )

    1990-06-01

    The potential of low-dose computed tomography (CT) of the lungs was critically evaluated in two patients with normal-appearing lungs and 10 patients with a wide diversity of underlying parenchymal abnormalities. At each of five levels, in addition to routine scans obtained at 120 kVp and 140 mA, a scan at 10 mA and a half scan at 10 mA were obtained, with all other parameters held constant. Each scan was evaluated visually to assess anatomic clarity as well as the presence of artifacts and the extent of graininess. At all levels of the thorax, visualization of parenchymal structures was not affected by decreasing the milliamperage. It appears that high-quality, diagnostic images of the lung can be obtained with a very low radiation dose. Although further evaluation is necessary, the potential of low-dose CT for use in the pediatric population in particular, as well as for screening in patients at high risk for developing lung cancer, is apparent.

  4. Ultra low-dose CT attenuation correction in PET SPM

    NASA Astrophysics Data System (ADS)

    Wang, Shyh-Jen; Yang, Bang-Hung; Tsai, Chia-Jung; Yang, Ching-Ching; Lee, Jason J. S.; Wu, Tung-Hsin

    2010-07-01

    The use of CT images for attenuation correction (CTAC) allows significantly shorter scanning time and a high quality noise-free attenuation map compared with conventional germanium-68 transmission scan because at least 10 4 times greater of photon flux would be generated from a CT scan under standard operating condition. However, this CTAC technique would potentially introduce more radiation risk to the patients owing to the higher radiation exposure from CT scan. Statistic parameters mapping (SPM) is a prominent technique in nuclear medicine community for the analysis of brain imaging data. The purpose of this study is to assess the feasibility of low-dose CT (LDCT) and ultra low-dose CT (UDCT) in PET SPM applications. The study was divided into two parts. The first part was to evaluate of tracer uptake distribution pattern and quantity analysis by using the striatal phantom to initially assess the feasibility of AC for clinical purpose. The second part was to examine the group SPM analysis using the Hoffman brain phantom. The phantom study is to simulate the human brain and to reduce the experimental uncertainty of real subjects. The initial studies show that the results of PET SPM analysis have no significant differences between LDCT and UDCT comparing to the current used default CTAC. Moreover, the dose of the LDCT is lower than that of the default CT by a factor of 9, and UDCT can even yield a 42 times dose reduction. We have demonstrated the SPM results while using LDCT and UDCT for PET AC is comparable to those using default CT setting, suggesting their feasibility in PET SPM applications. In addition, the necessity of UDCT in PET SPM studies to avoid excess radiation dose is also evident since most of the subjects involved are non-cancer patients or children and some normal subjects are even served as a comparison group in the experiment. It is our belief that additional attempts to decrease the radiation dose would be valuable, especially for children and

  5. Personalized low dose CT via variable kVp

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Jin, Yannan; Yao, Yangyang; Wu, Mingye; Yan, Ming; Tao, Kun; Yin, Zhye; De Man, Bruno

    2015-03-01

    Computerized Tomography (CT) is a powerful radiographic imaging technology but the health risk due to the exposure of x-ray radiation has drawn wide concern. In this study, we propose to use kVp modulation to reduce the radiation dose and achieve the personalized low dose CT. Two sets of simulation are performed to demonstrate the effectiveness of kVp modulation and the corresponding calibration. The first simulation used the helical body phantom (HBP) that is an elliptical water cylinder with high density bone inserts. The second simulation uses the NCAT phantom to emulate the practical use of kVp modulation approach with region of interest (ROI) selected in the cardiac region. The kVp modulation profile could be optimized view by view based on the knowledge of patient attenuation. A second order correction is applied to eliminate the beam hardening artifacts. To simplify the calibration process, we first generate the calibration vectors for a few representative spectra and then acquire other calibration vectors with interpolation. The simulation results demonstrate the beam hardening artifacts in the images with kVp modulation can be eliminated with proper beam hardening correction. The results also show that the simplification of calibration did not impair the image quality: the calibration with the simplified and the complete vectors both eliminate the artifacts effectively and the results are comparable. In summary, this study demonstrates the feasibility of kVp modulation and gives a practical way to calibrate the high order beam hardening artifacts.

  6. Ultra-low dose CT attenuation correction for PET/CT

    NASA Astrophysics Data System (ADS)

    Xia, Ting; Alessio, Adam M.; De Man, Bruno; Manjeshwar, Ravindra; Asma, Evren; Kinahan, Paul E.

    2012-01-01

    A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging.

  7. Low-dose interpolated average CT for attenuation correction in cardiac PET/CT

    NASA Astrophysics Data System (ADS)

    Wu, Tung-Hsin; Zhang, Geoffrey; Wang, Shyh-Jen; Chen, Chih-Hao; Yang, Bang-Hung; Wu, Nien-Yun; Huang, Tzung-Chi

    2010-07-01

    Because of the advantages in the use of high photon flux and thus the short scan times of CT imaging, the traditional 68Ge scans for positron emission tomography (PET) image attenuation correction have been replaced by CT scans in the modern PET/CT technology. The combination of fast CT scan and slow PET scan often causes image misalignment between the PET and CT images due to respiration motion. Use of the average CT derived from cine CT images is reported to reduce such misalignment. However, the radiation dose to patients is higher with cine CT scans. This study introduces a method that uses breath-hold CT images and their interpolations to generate the average CT for PET image attenuation correction. Breath-hold CT sets are taken at end-inspiration and end-expiration. Deformable image registration is applied to generate a voxel-to-voxel motion matrix between the two CT sets. The motion is equally divided into 5 steps from inspiration to expiration and 5 steps from expiration to inspiration, generating a total of 8 phases of interpolated CT sets. An average CT image is generated from all the 10 phase CT images, including original inhale/exhale CT and 8 interpolated CT sets. Quantitative comparison shows that the reduction of image misalignment artifacts using the average CT from the interpolation technique for PET attenuation correction is at a similar level as that using cine average CT, while the dose to the patient from the CT scans is reduced significantly. The interpolated average CT method hence provides a low dose alternative to cine CT scans for PET attenuation correction.

  8. Low dose dynamic myocardial CT perfusion using advanced iterative reconstruction

    NASA Astrophysics Data System (ADS)

    Eck, Brendan L.; Fahmi, Rachid; Fuqua, Christopher; Vembar, Mani; Dhanantwari, Amar; Bezerra, Hiram G.; Wilson, David L.

    2015-03-01

    Dynamic myocardial CT perfusion (CTP) can provide quantitative functional information for the assessment of coronary artery disease. However, x-ray dose in dynamic CTP is high, typically from 10mSv to >20mSv. We compared the dose reduction potential of advanced iterative reconstruction, Iterative Model Reconstruction (IMR, Philips Healthcare, Cleveland, Ohio) to hybrid iterative reconstruction (iDose4) and filtered back projection (FBP). Dynamic CTP scans were obtained using a porcine model with balloon-induced ischemia in the left anterior descending coronary artery to prescribed fractional flow reserve values. High dose dynamic CTP scans were acquired at 100kVp/100mAs with effective dose of 23mSv. Low dose scans at 75mAs, 50mAs, and 25mAs were simulated by adding x-ray quantum noise and detector electronic noise to the projection space data. Images were reconstructed with FBP, iDose4, and IMR at each dose level. Image quality in static CTP images was assessed by SNR and CNR. Blood flow was obtained using a dynamic CTP analysis pipeline and blood flow image quality was assessed using flow-SNR and flow-CNR. IMR showed highest static image quality according to SNR and CNR. Blood flow in FBP was increasingly over-estimated at reduced dose. Flow was more consistent for iDose4 from 100mAs to 50mAs, but was over-estimated at 25mAs. IMR was most consistent from 100mAs to 25mAs. Static images and flow maps for 100mAs FBP, 50mAs iDose4, and 25mAs IMR showed comparable, clear ischemia, CNR, and flow-CNR values. These results suggest that IMR can enable dynamic CTP at significantly reduced dose, at 5.8mSv or 25% of the comparable 23mSv FBP protocol.

  9. Improving abdomen tumor low-dose CT images using a fast dictionary learning based processing

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Yin, Xindao; Shi, Luyao; Shu, Huazhong; Luo, Limin; Coatrieux, Jean-Louis; Toumoulin, Christine

    2013-08-01

    In abdomen computed tomography (CT), repeated radiation exposures are often inevitable for cancer patients who receive surgery or radiotherapy guided by CT images. Low-dose scans should thus be considered in order to avoid the harm of accumulative x-ray radiation. This work is aimed at improving abdomen tumor CT images from low-dose scans by using a fast dictionary learning (DL) based processing. Stemming from sparse representation theory, the proposed patch-based DL approach allows effective suppression of both mottled noise and streak artifacts. The experiments carried out on clinical data show that the proposed method brings encouraging improvements in abdomen low-dose CT images with tumors.

  10. Low-dose high-resolution CT of lung parenchyma

    SciTech Connect

    Zwirewich, C.V.; Mayo, J.R.; Mueller, N.L. )

    1991-08-01

    To evaluate the efficacy of low-dose high-resolution computed tomography (HRCT) in the assessment of lung parenchyma, three observers reviewed the scans of 31 patients. The 1.5-mm-collimation, 2-second, 120-kVp scans were obtained at 20 and 200 mA at selected identical levels in the chest. The observers evaluated the visualization of normal pulmonary anatomy, various parenchymal abnormalities and their distribution, and artifacts. The low-dose and conventional scans were equivalent in the evaluation of vessels, lobar and segmental bronchi, and anatomy of secondary pulmonary lobules, and in characterizing the extent and distribution of reticulation, honeycomb cysts, and thickened interlobular septa. The low-dose technique failed to demonstrate ground-glass opacity in two of 10 cases (20%) and emphysema in one of nine cases (11%), in which they were evident but subtle on the high-dose scans. These differences were not statistically significant. Linear streak artifact was more prominent on images acquired with the low-dose technique, but the two techniques were judged equally diagnostic in 97% of cases. The authors conclude that HRCT images acquired at 20 mA yield anatomic information equivalent to that obtained with 200-mA scans in the majority of patients, without significant loss of spatial resolution or image degradation due to linear streak artifact.

  11. 20 percent lower lung cancer mortality with low-dose CT vs chest X-ray

    Cancer.gov

    Scientists have found a 20 percent reduction in deaths from lung cancer among current or former heavy smokers who were screened with low-dose helical computed tomography (CT) versus those screened by chest X-ray.

  12. Attenuation correction of PET cardiac data with low-dose average CT in PET/CT

    SciTech Connect

    Pan Tinsu; Mawlawi, Osama; Luo, Dershan; Liu, Hui H.; Chi Paichun, M.; Mar, Martha V.; Gladish, Gregory; Truong, Mylene; Erasmus, Jeremy Jr.; Liao Zhongxing; Macapinlac, H. A.

    2006-10-15

    We proposed a low-dose average computer tomography (ACT) for attenuation correction (AC) of the PET cardiac data in PET/CT. The ACT was obtained from a cine CT scan of over one breath cycle per couch position while the patient was free breathing. We applied this technique on four patients who underwent tumor imaging with {sup 18}F-FDG in PET/CT, whose PET data showed high uptake of {sup 18}F-FDG in the heart and whose CT and PET data had misregistration. All four patients did not have known myocardiac infarction or ischemia. The patients were injected with 555-740 MBq of {sup 18}F-FDG and scanned 1 h after injection. The helical CT (HCT) data were acquired in 16 s for the coverage of 100 cm. The PET acquisition was 3 min per bed of 15 cm. The duration of cine CT acquisition per 2 cm was 5.9 s. We used a fast gantry rotation cycle time of 0.5 s to minimize motion induced reconstruction artifacts in the cine CT images, which were averaged to become the ACT images for AC of the PET data. The radiation dose was about 5 mGy for 5.9 s cine duration. The selection of 5.9 s was based on our analysis of the respiratory signals of 600 patients; 87% of the patients had average breath cycles of less than 6 s and 90% had standard deviations of less than 1 s in the period of breath cycle. In all four patient studies, registrations between the CT and the PET data were improved. An increase of average uptake in the anterior and the lateral walls up to 48% and a decrease of average uptake in the septal and the inferior walls up to 16% with ACT were observed. We also compared ACT and conventional slow scan CT (SSCT) of 4 s duration in one patient study and found ACT was better than SSCT in depicting average respiratory motion and the SSCT images showed motion-induced reconstruction artifacts. In conclusion, low-dose ACT improved registration of the CT and the PET data in the heart region in our study of four patients. ACT was superior than SSCT for depicting average respiration

  13. Spectrotemporal CT data acquisition and reconstruction at low dose

    SciTech Connect

    Clark, Darin P.; Badea, Cristian T.; Lee, Chang-Lung; Kirsch, David G.

    2015-11-15

    Purpose: X-ray computed tomography (CT) is widely used, both clinically and preclinically, for fast, high-resolution anatomic imaging; however, compelling opportunities exist to expand its use in functional imaging applications. For instance, spectral information combined with nanoparticle contrast agents enables quantification of tissue perfusion levels, while temporal information details cardiac and respiratory dynamics. The authors propose and demonstrate a projection acquisition and reconstruction strategy for 5D CT (3D + dual energy + time) which recovers spectral and temporal information without substantially increasing radiation dose or sampling time relative to anatomic imaging protocols. Methods: The authors approach the 5D reconstruction problem within the framework of low-rank and sparse matrix decomposition. Unlike previous work on rank-sparsity constrained CT reconstruction, the authors establish an explicit rank-sparse signal model to describe the spectral and temporal dimensions. The spectral dimension is represented as a well-sampled time and energy averaged image plus regularly undersampled principal components describing the spectral contrast. The temporal dimension is represented as the same time and energy averaged reconstruction plus contiguous, spatially sparse, and irregularly sampled temporal contrast images. Using a nonlinear, image domain filtration approach, the authors refer to as rank-sparse kernel regression, the authors transfer image structure from the well-sampled time and energy averaged reconstruction to the spectral and temporal contrast images. This regularization strategy strictly constrains the reconstruction problem while approximately separating the temporal and spectral dimensions. Separability results in a highly compressed representation for the 5D data in which projections are shared between the temporal and spectral reconstruction subproblems, enabling substantial undersampling. The authors solved the 5D reconstruction

  14. Automated coronary artery calcification detection on low-dose chest CT images

    NASA Astrophysics Data System (ADS)

    Xie, Yiting; Cham, Matthew D.; Henschke, Claudia; Yankelevitz, David; Reeves, Anthony P.

    2014-03-01

    Coronary artery calcification (CAC) measurement from low-dose CT images can be used to assess the risk of coronary artery disease. A fully automatic algorithm to detect and measure CAC from low-dose non-contrast, non-ECG-gated chest CT scans is presented. Based on the automatically detected CAC, the Agatston score (AS), mass score and volume score were computed. These were compared with scores obtained manually from standard-dose ECG-gated scans and low-dose un-gated scans of the same patient. The automatic algorithm segments the heart region based on other pre-segmented organs to provide a coronary region mask. The mitral valve and aortic valve calcification is identified and excluded. All remaining voxels greater than 180HU within the mask region are considered as CAC candidates. The heart segmentation algorithm was evaluated on 400 non-contrast cases with both low-dose and regular dose CT scans. By visual inspection, 371 (92.8%) of the segmentations were acceptable. The automated CAC detection algorithm was evaluated on 41 low-dose non-contrast CT scans. Manual markings were performed on both low-dose and standard-dose scans for these cases. Using linear regression, the correlation of the automatic AS with the standard-dose manual scores was 0.86; with the low-dose manual scores the correlation was 0.91. Standard risk categories were also computed. The automated method risk category agreed with manual markings of gated scans for 24 cases while 15 cases were 1 category off. For low-dose scans, the automatic method agreed with 33 cases while 7 cases were 1 category off.

  15. Fast reconstruction of low dose proton CT by sinogram interpolation

    NASA Astrophysics Data System (ADS)

    Hansen, David C.; Sangild Sørensen, Thomas; Rit, Simon

    2016-08-01

    Proton computed tomography (CT) has been demonstrated as a promising image modality in particle therapy planning. It can reduce errors in particle range calculations and consequently improve dose calculations. Obtaining a high imaging resolution has traditionally required computationally expensive iterative reconstruction techniques to account for the multiple scattering of the protons. Recently, techniques for direct reconstruction have been developed, but these require a higher imaging dose than the iterative methods. No previous work has compared the image quality of the direct and the iterative methods. In this article, we extend the methodology for direct reconstruction to be applicable for low imaging doses and compare the obtained results with three state-of-the-art iterative algorithms. We find that the direct method yields comparable resolution and image quality to the iterative methods, even at 1 mSv dose levels, while yielding a twentyfold speedup in reconstruction time over previously published iterative algorithms.

  16. CT Hounsfield Numbers of Soft Tissues on Unenhanced Abdominal CT Scans: Variability Between Two Different Manufacturers’ MDCT Scanners

    PubMed Central

    Lamba, Ramit; McGahan, John P.; Corwin, Michael T.; Li, Chin-Shang; Tran, Tien; Seibert, J. Anthony; Boone, John M.

    2016-01-01

    OBJECTIVE The purpose of this study is to determine whether Hounsfield numbers of soft tissues on unenhanced abdominal CT of the same patient vary on repeat scans done on two different manufacturers’ MDCT scanners. MATERIALS AND METHODS A database search was performed to identify patients older than 18 years who underwent unenhanced CT of the abdomen and pelvis performed both on a Volume CT (GE Healthcare) and a Definition AS Plus (Siemens Healthcare) 64-MDCT scanner within 12 months of each other. After excluding those patients for whom Hounsfield unit measurements would be affected by mitigating factors, 48 patients (mean age, 58.8 years) were identified. Hounsfield unit measurements were obtained in nine different soft-tissue anatomic locations on each scan, and the location of these sites was kept identical on each scan pair. Data were analyzed to evaluate Hounsfield unit differences between these scanners. RESULTS In general, there was a low consistency in the Hounsfield unit measurements for each of these sites on scans obtained by the two scanners, with the subcutaneous fat in the left posterolateral flank showing the lowest correlation (intraclass correlation coefficient, 0.198). There were differences in the Hounsfield unit measurements obtained in all anatomic sites on scans obtained by both scanners. Mean Hounsfield unit measurements obtained on the Definition AS Plus scanner were lower than those obtained on the Volume CT scanner, with the intriguing exception of the anterior midline subcutaneous fat Hounsfield unit measurements, which were higher on the Definition AS Plus scanner. All differences were statistically significant (p < 0.05). CONCLUSION Hounsfield unit measurements for unenhanced abdominal soft tissues of the same patient vary between scanners of two common MDCT manufacturers. PMID:25341139

  17. Low-dose performance of a whole-body research photon-counting CT scanner

    NASA Astrophysics Data System (ADS)

    Yu, Zhicong; Leng, Shuai; Kappler, Steffen; Hahn, Katharina; Li, Zhoubo; Halaweish, Ahmed F.; Henning, Andre; Ritman, Erik L.; McCollough, Cynthia H.

    2016-04-01

    Photon-counting CT (PCCT) is an emerging technique that may bring new possibilities to clinical practice. Compared to conventional CT, PCCT is able to exclude electronic noise that may severely impair image quality at low photon counts. This work focused on assessing the low-dose performance of a whole-body research PCCT scanner consisting of two subsystems, one equipped with an energy-integrating detector, and the other with a photon-counting detector. Evaluation of the low-dose performance of the research PCCT scanner was achieved by comparing the noise performance of the two subsystems, with an emphasis on examining the impact of electronic noise on image quality in low-dose situations.

  18. SU-E-P-03: Implementing a Low Dose Lung Screening CT Program Meeting Regulatory Requirements

    SciTech Connect

    LaFrance, M; Marsh, S; O'Donnell, G

    2014-06-01

    Purpose: To provide information pertaining to IROC Houston QA Center's (RPC) credentialing process for institutions participating in NCI-sponsored clinical trials. Purpose: Provide guidance to the Radiology Departments with the intent of implementing a Low Dose CT Screening Program using different CT Scanners with multiple techniques within the framework of the required state regulations. Method: State Requirements for the purpose of implementing a Low Dose CT Lung Protocol required working with the Radiology and Pulmonary Department in setting up a Low Dose Screening Protocol designed to reduce the radiation burden to the patients enrolled. Radiation dose measurements (CTDIvol) for various CT manufacturers (Siemens16, Siemens 64, Philips 64, and Neusoft128) for three different weight based protocols. All scans were reviewed by the Radiologist. Prior to starting a low dose lung screening protocol, information had to be submitted to the state for approval. Performing a Healing Arts protocol requires extensive information. This not only includes name and address of the applicant but a detailed description of the disease, the x-ray examination and the population to be examined. The unit had to be tested by a qualified expert using the technique charts. The credentials of all the operators, the supervisors and the Radiologists had to be submitted to the state. Results: All the appropriate documentation was sent to the state for review. The measured results between the Low Dose Protocol versus the default Adult Chest Protocol showed that there was a dose reduction of 65% for small (100-150 lb.) patient, 75% for the Medium patient (151-250 lbs.), and a 55% reduction for the Large patient ( over 250 lbs.). Conclusion: Measured results indicated that the Low Dose Protocol indeed lowered the screening patient's radiation dose and the institution was able to submit the protocol to the State's regulators.

  19. Ultra-Low Dose Lung CT Perfusion Regularized by a Previous Scan

    PubMed Central

    Yu, Hengyong; Zhao, Shiying; Hoffman, Eric A.; Wang, Ge

    2009-01-01

    Rationale and Objectives Our previous scan regularized reconstruction (PSRR) method is proposed to reduce radiation dose and applied for lung perfusion studies. The normal and ultra-low dose lung CT perfusion studies are compared in terms of estimation accuracy of pulmonary functional parameters. Materials and Methods A sequences of sheep lung scans were performed in three prone, anesthetized sheep at normal and ultra-low doses. A scan protocol was developed for the ultra-low dose studies with ECG gating - time point one for a normal x-ray dose scan (100kV/150mAs) and time points 2–21 for low dose scans (80kV/17mAs). A nonlinear diffusion-based post-filtering (NDPF) method was applied to the difference images between the low-dose images and the high-quality reference image. The final images at 20 time points were generated by fusing the reference image with the filtered difference images. Results The power spectra of perfusion images and coherences with the normal scans show a great improvement in image quality of the ultra-low dose scans with PSRR relative to that without RSRR. The Gamma variate-fitting and the repeatability of the measurements of the mean transit time demonstrate that the key parameters of lung functions can be reliably accessed using PSRR. The variability of the ultra-low dose scan results obtained using PSRR is not substantially different from that between two normal dose scans. Conclusions Our studies have shown that a ~90% reduction in radiation dose is achievable using PSRR without compromising the quantitative CT measurements of regional lung functions. PMID:19201366

  20. Algorithm of pulmonary emphysema extraction using low dose thoracic 3D CT images

    NASA Astrophysics Data System (ADS)

    Saita, S.; Kubo, M.; Kawata, Y.; Niki, N.; Nakano, Y.; Omatsu, H.; Tominaga, K.; Eguchi, K.; Moriyama, N.

    2006-03-01

    Recently, due to aging and smoking, emphysema patients are increasing. The restoration of alveolus which was destroyed by emphysema is not possible, thus early detection of emphysema is desired. We describe a quantitative algorithm for extracting emphysematous lesions and quantitatively evaluate their distribution patterns using low dose thoracic 3-D CT images. The algorithm identified lung anatomies, and extracted low attenuation area (LAA) as emphysematous lesion candidates. Applying the algorithm to 100 thoracic 3-D CT images and then by follow-up 3-D CT images, we demonstrate its potential effectiveness to assist radiologists and physicians to quantitatively evaluate the emphysematous lesions distribution and their evolution in time interval changes.

  1. Low dose dynamic CT myocardial perfusion imaging using a statistical iterative reconstruction method

    SciTech Connect

    Tao, Yinghua; Chen, Guang-Hong; Hacker, Timothy A.; Raval, Amish N.; Van Lysel, Michael S.; Speidel, Michael A.

    2014-07-15

    Purpose: Dynamic CT myocardial perfusion imaging has the potential to provide both functional and anatomical information regarding coronary artery stenosis. However, radiation dose can be potentially high due to repeated scanning of the same region. The purpose of this study is to investigate the use of statistical iterative reconstruction to improve parametric maps of myocardial perfusion derived from a low tube current dynamic CT acquisition. Methods: Four pigs underwent high (500 mA) and low (25 mA) dose dynamic CT myocardial perfusion scans with and without coronary occlusion. To delineate the affected myocardial territory, an N-13 ammonia PET perfusion scan was performed for each animal in each occlusion state. Filtered backprojection (FBP) reconstruction was first applied to all CT data sets. Then, a statistical iterative reconstruction (SIR) method was applied to data sets acquired at low dose. Image voxel noise was matched between the low dose SIR and high dose FBP reconstructions. CT perfusion maps were compared among the low dose FBP, low dose SIR and high dose FBP reconstructions. Numerical simulations of a dynamic CT scan at high and low dose (20:1 ratio) were performed to quantitatively evaluate SIR and FBP performance in terms of flow map accuracy, precision, dose efficiency, and spatial resolution. Results: Forin vivo studies, the 500 mA FBP maps gave −88.4%, −96.0%, −76.7%, and −65.8% flow change in the occluded anterior region compared to the open-coronary scans (four animals). The percent changes in the 25 mA SIR maps were in good agreement, measuring −94.7%, −81.6%, −84.0%, and −72.2%. The 25 mA FBP maps gave unreliable flow measurements due to streaks caused by photon starvation (percent changes of +137.4%, +71.0%, −11.8%, and −3.5%). Agreement between 25 mA SIR and 500 mA FBP global flow was −9.7%, 8.8%, −3.1%, and 26.4%. The average variability of flow measurements in a nonoccluded region was 16.3%, 24.1%, and 937

  2. Low dose dynamic CT myocardial perfusion imaging using a statistical iterative reconstruction method

    PubMed Central

    Tao, Yinghua; Chen, Guang-Hong; Hacker, Timothy A.; Raval, Amish N.; Van Lysel, Michael S.; Speidel, Michael A.

    2014-01-01

    Purpose: Dynamic CT myocardial perfusion imaging has the potential to provide both functional and anatomical information regarding coronary artery stenosis. However, radiation dose can be potentially high due to repeated scanning of the same region. The purpose of this study is to investigate the use of statistical iterative reconstruction to improve parametric maps of myocardial perfusion derived from a low tube current dynamic CT acquisition. Methods: Four pigs underwent high (500 mA) and low (25 mA) dose dynamic CT myocardial perfusion scans with and without coronary occlusion. To delineate the affected myocardial territory, an N-13 ammonia PET perfusion scan was performed for each animal in each occlusion state. Filtered backprojection (FBP) reconstruction was first applied to all CT data sets. Then, a statistical iterative reconstruction (SIR) method was applied to data sets acquired at low dose. Image voxel noise was matched between the low dose SIR and high dose FBP reconstructions. CT perfusion maps were compared among the low dose FBP, low dose SIR and high dose FBP reconstructions. Numerical simulations of a dynamic CT scan at high and low dose (20:1 ratio) were performed to quantitatively evaluate SIR and FBP performance in terms of flow map accuracy, precision, dose efficiency, and spatial resolution. Results: Forin vivo studies, the 500 mA FBP maps gave −88.4%, −96.0%, −76.7%, and −65.8% flow change in the occluded anterior region compared to the open-coronary scans (four animals). The percent changes in the 25 mA SIR maps were in good agreement, measuring −94.7%, −81.6%, −84.0%, and −72.2%. The 25 mA FBP maps gave unreliable flow measurements due to streaks caused by photon starvation (percent changes of +137.4%, +71.0%, −11.8%, and −3.5%). Agreement between 25 mA SIR and 500 mA FBP global flow was −9.7%, 8.8%, −3.1%, and 26.4%. The average variability of flow measurements in a nonoccluded region was 16.3%, 24.1%, and 937

  3. Improving low-dose cardiac CT images using 3D sparse representation based processing

    NASA Astrophysics Data System (ADS)

    Shi, Luyao; Chen, Yang; Luo, Limin

    2015-03-01

    Cardiac computed tomography (CCT) has been widely used in diagnoses of coronary artery diseases due to the continuously improving temporal and spatial resolution. When helical CT with a lower pitch scanning mode is used, the effective radiation dose can be significant when compared to other radiological exams. Many methods have been developed to reduce radiation dose in coronary CT exams including high pitch scans using dual source CT scanners and step-and-shot scanning mode for both single source and dual source CT scanners. Additionally, software methods have also been proposed to reduce noise in the reconstructed CT images and thus offering the opportunity to reduce radiation dose while maintaining the desired diagnostic performance of a certain imaging task. In this paper, we propose that low-dose scans should be considered in order to avoid the harm from accumulating unnecessary X-ray radiation. However, low dose CT (LDCT) images tend to be degraded by quantum noise and streak artifacts. Accordingly, in this paper, a 3D dictionary representation based image processing method is proposed to reduce CT image noise. Information on both spatial and temporal structure continuity is utilized in sparse representation to improve the performance of the image processing method. Clinical cases were used to validate the proposed method.

  4. Spectrum of early lung cancer presentation in low-dose screening CT: a pictorial review.

    PubMed

    Rampinelli, Cristiano; Calloni, Sonia Francesca; Minotti, Marta; Bellomi, Massimo

    2016-06-01

    The typical presentation of early stage lung cancers on low-dose CT screening are non-calcified pulmonary nodules. However, there is a wide spectrum of unusual focal abnormalities that can be early presentations of lung cancer. These abnormalities include, for example, cancers associated with 'cystic airspaces' or scar-like cancers. The detection of lung cancer with low-dose CT can be affected by the absence of intravenous contrast medium. As a consequence, endobronchial and central lesions can be difficult to recognize, raising the potential for missed cancers. Focal lesions arising within pre-existing lung disease, such as lung fibrosis or apical scars, can also be early lung cancer manifestations and deserve particular consideration as recognition of these lesions may be hindered by the underlying disease. Furthermore, the unpredictable growth rate of lung cancer, which ranges from indolent to aggressive cancers, necessitates attention to the wide spectrum of progression in lung cancer appearance on serial low-dose CT scans. In this pictorial review we discuss the spectrum of early lung cancer presentation in low-dose CT screening, highlighting typical as well as unusual radiological features and the varied growth rates of early lung cancer. Teaching Points • There is a wide spectrum of early presentations of lung cancer on LDCT. • Low radiation dose and the absence of contrast medium injection can affect lung cancer detection. • Lung cancer growth shows various behaviours, ranging from indolent to aggressive cancers. • Familiarity with LDCT technique can improve CT screening effectiveness and avoid missed diagnosis. PMID:27188380

  5. Low-dose X-ray CT reconstruction via dictionary learning.

    PubMed

    Xu, Qiong; Yu, Hengyong; Mou, Xuanqin; Zhang, Lei; Hsieh, Jiang; Wang, Ge

    2012-09-01

    Although diagnostic medical imaging provides enormous benefits in the early detection and accuracy diagnosis of various diseases, there are growing concerns on the potential side effect of radiation induced genetic, cancerous and other diseases. How to reduce radiation dose while maintaining the diagnostic performance is a major challenge in the computed tomography (CT) field. Inspired by the compressive sensing theory, the sparse constraint in terms of total variation (TV) minimization has already led to promising results for low-dose CT reconstruction. Compared to the discrete gradient transform used in the TV method, dictionary learning is proven to be an effective way for sparse representation. On the other hand, it is important to consider the statistical property of projection data in the low-dose CT case. Recently, we have developed a dictionary learning based approach for low-dose X-ray CT. In this paper, we present this method in detail and evaluate it in experiments. In our method, the sparse constraint in terms of a redundant dictionary is incorporated into an objective function in a statistical iterative reconstruction framework. The dictionary can be either predetermined before an image reconstruction task or adaptively defined during the reconstruction process. An alternating minimization scheme is developed to minimize the objective function. Our approach is evaluated with low-dose X-ray projections collected in animal and human CT studies, and the improvement associated with dictionary learning is quantified relative to filtered backprojection and TV-based reconstructions. The results show that the proposed approach might produce better images with lower noise and more detailed structural features in our selected cases. However, there is no proof that this is true for all kinds of structures. PMID:22542666

  6. Low-Dose X-ray CT Reconstruction via Dictionary Learning

    PubMed Central

    Xu, Qiong; Zhang, Lei; Hsieh, Jiang; Wang, Ge

    2013-01-01

    Although diagnostic medical imaging provides enormous benefits in the early detection and accuracy diagnosis of various diseases, there are growing concerns on the potential side effect of radiation induced genetic, cancerous and other diseases. How to reduce radiation dose while maintaining the diagnostic performance is a major challenge in the computed tomography (CT) field. Inspired by the compressive sensing theory, the sparse constraint in terms of total variation (TV) minimization has already led to promising results for low-dose CT reconstruction. Compared to the discrete gradient transform used in the TV method, dictionary learning is proven to be an effective way for sparse representation. On the other hand, it is important to consider the statistical property of projection data in the low-dose CT case. Recently, we have developed a dictionary learning based approach for low-dose X-ray CT. In this paper, we present this method in detail and evaluate it in experiments. In our method, the sparse constraint in terms of a redundant dictionary is incorporated into an objective function in a statistical iterative reconstruction framework. The dictionary can be either predetermined before an image reconstruction task or adaptively defined during the reconstruction process. An alternating minimization scheme is developed to minimize the objective function. Our approach is evaluated with low-dose X-ray projections collected in animal and human CT studies, and the improvement associated with dictionary learning is quantified relative to filtered backprojection and TV-based reconstructions. The results show that the proposed approach might produce better images with lower noise and more detailed structural features in our selected cases. However, there is no proof that this is true for all kinds of structures. PMID:22542666

  7. Investigation of iterative image reconstruction in low-dose breast CT

    NASA Astrophysics Data System (ADS)

    Bian, Junguo; Yang, Kai; Boone, John M.; Han, Xiao; Sidky, Emil Y.; Pan, Xiaochuan

    2014-06-01

    There is interest in developing computed tomography (CT) dedicated to breast-cancer imaging. Because breast tissues are radiation-sensitive, the total radiation exposure in a breast-CT scan is kept low, often comparable to a typical two-view mammography exam, thus resulting in a challenging low-dose-data-reconstruction problem. In recent years, evidence has been found that suggests that iterative reconstruction may yield images of improved quality from low-dose data. In this work, based upon the constrained image total-variation minimization program and its numerical solver, i.e., the adaptive steepest descent-projection onto the convex set (ASD-POCS), we investigate and evaluate iterative image reconstructions from low-dose breast-CT data of patients, with a focus on identifying and determining key reconstruction parameters, devising surrogate utility metrics for characterizing reconstruction quality, and tailoring the program and ASD-POCS to the specific reconstruction task under consideration. The ASD-POCS reconstructions appear to outperform the corresponding clinical FDK reconstructions, in terms of subjective visualization and surrogate utility metrics.

  8. Detecting airway remodeling in COPD and emphysema using low-dose CT imaging

    NASA Astrophysics Data System (ADS)

    Rudyanto, R.; Ceresa, M.; Muñoz-Barrutia, A.; Ortiz-de-Solorzano, C.

    2012-03-01

    In this study, we quantitatively characterize lung airway remodeling caused by smoking-related emphysema and Chronic Obstructive Pulmonary Disease (COPD), in low-dose CT scans. To that end, we established three groups of individuals: subjects with COPD (n=35), subjects with emphysema (n=38) and healthy smokers (n=28). All individuals underwent a low-dose CT scan, and the images were analyzed as described next. First the lung airways were segmented using a fast marching method and labeled according to its generation. Along each airway segment, cross-section images were resampled orthogonal to the airway axis. Next 128 rays were cast from the center of the airway lumen in each crosssection slice. Finally, we used an integral-based method, to measure lumen radius, wall thickness, mean wall percentage and mean peak wall attenuation on every cast ray. Our analysis shows that both the mean global wall thickness and the lumen radius of the airways of both COPD and emphysema groups were significantly different from those of the healthy group. In addition, the wall thickness change starts at the 3rd airway generation in the COPD patients compared with emphysema patients, who display the first significant changes starting in the 2nd generation. In conclusion, it is shown that airway remodeling happens in individuals suffering from either COPD or emphysema, with some local difference between both groups, and that we are able to detect and accurately quantify this process using images of low-dose CT scans.

  9. Effects of filtering on colorectal polyp detection in ultra low dose CT

    NASA Astrophysics Data System (ADS)

    Schoonenberg, Gert A.; de Vries, Ayso; Grigorescu, Simona; Peters, Joost; Vilanova, Anna; Truyen, Roel; Stoker, Jaap; Gerritsen, Frans

    2006-03-01

    We have evaluated the feasibility of polyp detection on simulated ultra low dose CT Colonography data by a computer aided polyp detection (CAD) algorithm. We compared the results of ultra low dose to normal dose data. Twenty-three extensively prepared patients were scanned in prone and supine position at 25 to 100 mAs (average 70 mAs) depending on their waist circumference. Noise was added and the scans were reconstructed at 6.25 and 1.39 mAs. To evaluate the performance of the CAD system, polyps detected by an experienced reviewer and confirmed at colonoscopy were used as ground truth. Curvature, concavity and sphericity of the colon surface were used to detect polyp candidates. Bilateral filtering was used to reduce noise. We present the results for 40 polyps of 6 mm or larger as measured during colonoscopy. The by-polyp sensitivity was 80% for medium size polyps (6-9 mm) and 97% for large polyps (10 mm or larger) at an average value of 5 false-positives per scan for normal dose data. The by-polyp sensitivity was 81% for medium size polyps and 85% for large size polyps at an average value of 5 false-positives per scan for low dose data (6.25 mAs). Finally for the ultra low dose data (1.39 mAs) we achieved a by-polyp sensitivity of 75% for medium size polyps and 97% for large polyps at an average value of 5 false-positives per scan. The conclusion of our study is that CAD for polyp detection is feasible on ultra low dose CT colonography data.

  10. A low dose simulation tool for CT systems with energy integrating detectors

    SciTech Connect

    Zabic, Stanislav; Morton, Thomas; Brown, Kevin M.; Wang Qiu

    2013-03-15

    Purpose: This paper introduces a new strategy for simulating low-dose computed tomography (CT) scans using real scans of a higher dose as an input. The tool is verified against simulations and real scans and compared to other approaches found in the literature. Methods: The conditional variance identity is used to properly account for the variance of the input high-dose data, and a formula is derived for generating a new Poisson noise realization which has the same mean and variance as the true low-dose data. The authors also derive a formula for the inclusion of real samples of detector noise, properly scaled according to the level of the simulated x-ray signals. Results: The proposed method is shown to match real scans in number of experiments. Noise standard deviation measurements in simulated low-dose reconstructions of a 35 cm water phantom match real scans in a range from 500 to 10 mA with less than 5% error. Mean and variance of individual detector channels are shown to match closely across the detector array. Finally, the visual appearance of noise and streak artifacts is shown to match in real scans even under conditions of photon-starvation (with tube currents as low as 10 and 80 mA). Additionally, the proposed method is shown to be more accurate than previous approaches (1) in achieving the correct mean and variance in reconstructed images from pure-Poisson noise simulations (with no detector noise) under photon-starvation conditions, and (2) in simulating the correct noise level and detector noise artifacts in real low-dose scans. Conclusions: The proposed method can accurately simulate low-dose CT data starting from high-dose data, including effects from photon starvation and detector noise. This is potentially a very useful tool in helping to determine minimum dose requirements for a wide range of clinical protocols and advanced reconstruction algorithms.

  11. A framework to measure myocardial extracellular volume fraction using dual-phase low dose CT images

    SciTech Connect

    Liu, Yixun; Summers, Ronald M.; Yao, Jianhua; Liu, Songtao; Sibley, Christopher T.; Bluemke, David A.; Nacif, Marcelo S.

    2013-10-15

    Purpose: Myocardial extracellular volume fraction (ECVF) is a surrogate imaging biomarker of diffuse myocardial fibrosis, a hallmark of pathologic ventricular remodeling. Low dose cardiac CT is emerging as a promising modality to detect diffuse interstitial myocardial fibrosis due to its fast acquisition and low radiation; however, the insufficient contrast in the low dose CT images poses great challenge to measure ECVF from the image. Methods: To deal with this difficulty, the authors present a complete ECVF measurement framework including a point-guided myocardial modeling, a deformable model-based myocardium segmentation, nonrigid registration of pre- and post-CT, and ECVF calculation. Results: The proposed method was evaluated on 20 patients by two observers. Compared to the manually delineated reference segmentations, the accuracy of our segmentation in terms of true positive volume fraction (TPVF), false positive volume fraction (FPVF), and average surface distance (ASD), were 92.18% ± 3.52%, 0.31% ± 0.10%, 0.69 ± 0.14 mm, respectively. The interobserver variability measured by concordance correlation coefficient regarding TPVF, FPVF, and ASD were 0.95, 0.90, 0.94, respectively, demonstrating excellent agreement. Bland-Altman method showed 95% limits of agreement between ECVF at CT and ECVF at MR. Conclusions: The proposed framework demonstrates its efficiency, accuracy, and noninvasiveness in ECVF measurement and dramatically advances the ECVF at cardiac CT toward its clinical use.

  12. Automated segmentation of cardiac visceral fat in low-dose non-contrast chest CT images

    NASA Astrophysics Data System (ADS)

    Xie, Yiting; Liang, Mingzhu; Yankelevitz, David F.; Henschke, Claudia I.; Reeves, Anthony P.

    2015-03-01

    Cardiac visceral fat was segmented from low-dose non-contrast chest CT images using a fully automated method. Cardiac visceral fat is defined as the fatty tissues surrounding the heart region, enclosed by the lungs and posterior to the sternum. It is measured by constraining the heart region with an Anatomy Label Map that contains robust segmentations of the lungs and other major organs and estimating the fatty tissue within this region. The algorithm was evaluated on 124 low-dose and 223 standard-dose non-contrast chest CT scans from two public datasets. Based on visual inspection, 343 cases had good cardiac visceral fat segmentation. For quantitative evaluation, manual markings of cardiac visceral fat regions were made in 3 image slices for 45 low-dose scans and the Dice similarity coefficient (DSC) was computed. The automated algorithm achieved an average DSC of 0.93. Cardiac visceral fat volume (CVFV), heart region volume (HRV) and their ratio were computed for each case. The correlation between cardiac visceral fat measurement and coronary artery and aortic calcification was also evaluated. Results indicated the automated algorithm for measuring cardiac visceral fat volume may be an alternative method to the traditional manual assessment of thoracic region fat content in the assessment of cardiovascular disease risk.

  13. Automated segmentation of brain ventricles in unenhanced CT of patients with ischemic stroke

    NASA Astrophysics Data System (ADS)

    Qian, Xiaohua; Wang, Jiahui; Li, Qiang

    2013-02-01

    We are developing an automated method for detection and quantification of ischemic stroke in computed tomography (CT). Ischemic stroke often connects to brain ventricle, therefore, ventricular segmentation is an important and difficult task when stroke is present, and is the topic of this study. We first corrected inclination angle of brain by aligning midline of brain with the vertical centerline of a slice. We then estimated the intensity range of the ventricles by use of the k-means method. Two segmentation of the ventricle were obtained by use of thresholding technique. One segmentation contains ventricle and nearby stroke. The other mainly contains ventricle. Therefore, the stroke regions can be extracted and removed using image difference technique. An adaptive template-matching algorithm was employed to identify objects in the fore-mentioned segmentation. The largest connected component was identified and considered as the ventricle. We applied our method to 25 unenhanced CT scans with stroke. Our method achieved average Dice index, sensitivity, and specificity of 95.1%, 97.0%, and 99.8% for the entire ventricular regions. The experimental results demonstrated that the proposed method has great potential in detection and quantification of stroke and other neurologic diseases.

  14. Dictionary learning based low-dose x-ray CT reconstruction using a balancing principle

    NASA Astrophysics Data System (ADS)

    Mou, Xuanqin; Wu, Junfeng; Bai, Ti; Xu, Qiong; Yu, Hengyong; Wang, Ge

    2014-09-01

    The high utility and wide applicability of x-ray imaging has led to a rapidly increased number of CT scans over the past years, and at the same time an elevated public concern on the potential risk of x-ray radiation to patients. Hence, a hot topic is how to minimize x-ray dose while maintaining the image quality. The low-dose CT strategies include modulation of x-ray flux and minimization of dataset size. However, these methods will produce noisy and insufficient projection data, which represents a great challenge to image reconstruction. Our team has been working to combine statistical iterative methods and advanced image processing techniques, especially dictionary learning, and have produced excellent preliminary results. In this paper, we report recent progress in dictionary learning based low-dose CT reconstruction, and discuss the selection of regularization parameters that are crucial for the algorithmic optimization. The key idea is to use a "balancing principle" based on a model function to choose the regularization parameters during the iterative process, and to determine a weight factor empirically for address the noise level in the projection domain. Numerical and experimental results demonstrate the merits of our proposed reconstruction approach.

  15. A Longitudinal Low Dose μCT Analysis of Bone Healing in Mice: A Pilot Study.

    PubMed

    Di, Lu-Zhao; Couture, Vanessa; Leblanc, Elisabeth; Alinejad, Yasaman; Beaudoin, Jean-François; Lecomte, Roger; Berthod, François; Faucheux, Nathalie; Balg, Frédéric; Grenier, Guillaume

    2014-01-01

    Low dose microcomputed tomography (μCT) is a recently matured technique that enables the study of longitudinal bone healing and the testing of experimental treatments for bone repair. This imaging technique has been used for studying craniofacial repair in mice but not in an orthopedic context. This is mainly due to the size of the defects (approximately 1.0 mm) in long bone, which heal rapidly and may thus negatively impact the assessment of the effectiveness of experimental treatments. We developed a longitudinal low dose μCT scan analysis method combined with a new image segmentation and extraction software using Hounsfield unit (HU) scores to quantitatively monitor bone healing in small femoral cortical defects in live mice. We were able to reproducibly quantify bone healing longitudinally over time with three observers. We used high speed intramedullary reaming to prolong healing in order to circumvent the rapid healing typical of small defects. Bone healing prolongation combined with μCT imaging to study small bone defects in live mice thus shows potential as a promising tool for future preclinical research on bone healing. PMID:25431676

  16. Automated measurement of pulmonary artery in low-dose non-contrast chest CT images

    NASA Astrophysics Data System (ADS)

    Xie, Yiting; Liang, Mingzhu; Yankelevitz, David F.; Henschke, Claudia I.; Reeves, Anthony P.

    2015-03-01

    A new measurement of the pulmonary artery diameter is obtained where the artery may be robustly segmented between the heart and the artery bifurcation. An automated algorithm is presented that can make this pulmonary artery measurement in low-dose non-contrast chest CT images. The algorithm uses a cylinder matching method following geometric constraints obtained from other adjacent organs that have been previously segmented. This new measurement and the related ratio of pulmonary artery to aortic artery measurement are compared to traditional manual approaches for pulmonary artery characterization. The algorithm was qualitatively evaluated on 124 low-dose and 223 standard-dose non-contrast chest CT scans from two public datasets; 324 out of the 347 cases had good segmentations and in the other 23 cases there was significant boundary inaccuracy. For quantitative evaluation, the comparison was to manually marked pulmonary artery boundary in an axial slice in 45 cases; the resulting average Dice Similarity Coefficient was 0.88 (max 0.95, min 0.74). For the 45 cases with manual markings, the correlation between the automated pulmonary artery to ascending aorta diameter ratio and manual ratio at pulmonary artery bifurcation level was 0.81. Using Bland-Altman analysis, the mean difference of the two ratios was 0.03 and the limits of agreement was (-0.12, 0.18). This automated measurement may have utility as an alternative to the conventional manual measurement of pulmonary artery diameter at the bifurcation level especially in the context of noisy low-dose CT images.

  17. Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms

    NASA Astrophysics Data System (ADS)

    Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M.; Asma, Evren; Kinahan, Paul E.; De Man, Bruno

    2015-09-01

    For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition. We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 s. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.043 75 mAs, were investigated. Both the analytical Feldkamp, Davis and Kress (FDK) algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality. With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose

  18. Ultra-low dose CT attenuation correction for PET/CT: analysis of sparse view data acquisition and reconstruction algorithms.

    PubMed

    Rui, Xue; Cheng, Lishui; Long, Yong; Fu, Lin; Alessio, Adam M; Asma, Evren; Kinahan, Paul E; De Man, Bruno

    2015-10-01

    For PET/CT systems, PET image reconstruction requires corresponding CT images for anatomical localization and attenuation correction. In the case of PET respiratory gating, multiple gated CT scans can offer phase-matched attenuation and motion correction, at the expense of increased radiation dose. We aim to minimize the dose of the CT scan, while preserving adequate image quality for the purpose of PET attenuation correction by introducing sparse view CT data acquisition.We investigated sparse view CT acquisition protocols resulting in ultra-low dose CT scans designed for PET attenuation correction. We analyzed the tradeoffs between the number of views and the integrated tube current per view for a given dose using CT and PET simulations of a 3D NCAT phantom with lesions inserted into liver and lung. We simulated seven CT acquisition protocols with {984, 328, 123, 41, 24, 12, 8} views per rotation at a gantry speed of 0.35 s. One standard dose and four ultra-low dose levels, namely, 0.35 mAs, 0.175 mAs, 0.0875 mAs, and 0.043 75 mAs, were investigated. Both the analytical Feldkamp, Davis and Kress (FDK) algorithm and the Model Based Iterative Reconstruction (MBIR) algorithm were used for CT image reconstruction. We also evaluated the impact of sinogram interpolation to estimate the missing projection measurements due to sparse view data acquisition. For MBIR, we used a penalized weighted least squares (PWLS) cost function with an approximate total-variation (TV) regularizing penalty function. We compared a tube pulsing mode and a continuous exposure mode for sparse view data acquisition. Global PET ensemble root-mean-squares-error (RMSE) and local ensemble lesion activity error were used as quantitative evaluation metrics for PET image quality.With sparse view sampling, it is possible to greatly reduce the CT scan dose when it is primarily used for PET attenuation correction with little or no measureable effect on the PET image. For the four ultra-low dose levels

  19. Texture-preserving Bayesian image reconstruction for low-dose CT

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Han, Hao; Hu, Yifan; Liu, Yan; Ma, Jianhua; Li, Lihong; Moore, William; Liang, Zhengrong

    2016-03-01

    Markov random field (MRF) model has been widely used in Bayesian image reconstruction to reconstruct piecewise smooth images in the presence of noise, such as in low-dose X-ray computed tomography (LdCT). While it can preserve edge sharpness via edge-preserving potential function, its regional smoothing may sacrifice tissue image textures, which have been recognized as useful imaging biomarkers, and thus it compromises clinical tasks such as differentiating malignant vs. benign lesions, e.g., lung nodule or colon polyp. This study aims to shift the edge preserving regional noise smoothing paradigm to texture-preserving framework for LdCT image reconstruction while retaining the advantage of MRF's neighborhood system on edge preservation. Specifically, we adapted the MRF model to incorporate the image textures of lung, bone, fat, muscle, etc. from previous full-dose CT scan as a priori knowledge for texture-preserving Bayesian reconstruction of current LdCT images. To show the feasibility of proposed reconstruction framework, experiments using clinical patient scans (with lung nodule or colon polyp) were conducted. The experimental outcomes showed noticeable gain by the a priori knowledge for LdCT image reconstruction with the well-known Haralick texture measures. Thus, it is conjectured that texture-preserving LdCT reconstruction has advantages over edge-preserving regional smoothing paradigm for texture-specific clinical applications.

  20. Dose exposure in the ITALUNG trial of lung cancer screening with low-dose CT

    PubMed Central

    Mascalchi, M; Mazzoni, L N; Falchini, M; Belli, G; Picozzi, G; Merlini, V; Vella, A; Diciotti, S; Falaschi, F; Lopes Pegna, A; Paci, E

    2012-01-01

    Few data are available on the effective dose received by participants in lung cancer screening programmes with low-dose CT (LDCT). We report the collective effective dose delivered to 1406 current or former smokers enrolled in the ITALUNG trial who completed 4 annual LDCT examinations and related further investigations including follow-up LDCT, 2-[18F]flu-2-deoxy-d-glucose positron emission tomography (FDG-PET) or CT-guided fine needle aspiration biopsy (FNAB). Using the air CT dose index and Monte Carlo simulations on an anthropomorphic phantom, the whole-body effective dose associated with LDCT was determined for the eight CT scanners used in the trial. A value of 7 mSv was assigned to FDG-PET while the measured mean effective dose of CT-guided FNAB was 1.5 mSv. The mean collective effective dose in the 1406 subjects ranged between 8.75 and 9.36 Sv and the mean effective dose to the single subject over 4 years was between 6.2 and 6.8 mSv (range 1.7–21.5 mSv) according to the cranial–caudal length of the LDCT volume. 77.4% of the dose was owing to annual LDCT and 22.6% to further investigations. Considering the nominal risk coefficients for stochastic effects after exposure to low-dose radiation according to the National Radiological Protection Board, International Commission on Radiological Protection (ICRP) 60, ICRP103 and Biological Effects of Ionizing Radiation VII, the mean number of radiation-induced cancers ranged between 0.12 and 0.33 per 1000 subjects. The individual effective dose to participants in a 4-year lung cancer screening programme with annual LDCT is very low and about one-third of the effective dose that is associated with natural background radiation and diagnostic radiology in the same time period. PMID:21976631

  1. Unenhanced CT for the evaluation of acute ureteric colic: the essential pictorial guide.

    PubMed

    Kennish, Steven J; Wah, Tze M; Irving, Henry C

    2010-07-01

    Acute ureteric colic is a common emergency, often dealt with by the emergency physician or general practitioner and referred on to the urologist. Unenhanced CT of the kidneys, ureters and bladder (CTKUB) is the 'gold standard' imaging investigation for establishing a diagnosis and guiding management. An appreciation of the CTKUB signs, which support or refute a diagnosis of ureteric colic, is highly valuable to the clinician when making a urological referral, and to the urologist, who must make appropriate management plans. All salient diagnostic and supportive features of ureteric colic are carefully illustrated, as are important radiological mimics, with the objectives of educating and informing the non-radiologist. Ready access to the picture archive and communication system (PACS) allows all specialists involved to interpret the radiological report with the benefit of images. A stone within the ureter may not always be readily apparent. Soft tissue rim sign around a calcific focus is an important indicator of a ureteric stone, whereas a comet tail sign suggests a phlebolith (a calcified venous thrombosis), a radiological mimic of a ureteric stone. Numerous secondary signs of ureteric obstruction may be present including hydronephrosis and perinephric stranding, and can help to confirm the diagnosis. The relative diagnostic weighting of signs is discussed, and a checklist is provided to assist with interpretation. Unexpected alternative radiological diagnoses are also illustrated, which may have significant management consequences necessitating specialist referral. PMID:20634253

  2. Low-dose dual-energy electronic cleansing for fecal-tagging CT Colonography

    NASA Astrophysics Data System (ADS)

    Cai, Wenli; Zhang, Da; Lee, June-Goo; Yoshida, Hiroyuki

    2013-03-01

    Dual-energy electronic cleansing (DE-EC) provides a promising means for cleansing the tagged fecal materials in fecaltagging CT colonography (CTC). However, the increased radiation dose due to the double exposures in dual-energy CTC (DE-CTC) scanning is a major limitation for the use of DE-EC in clinical practice. The purpose of this study was to develop and evaluate a low-dose DE-EC scheme in fecal-tagging DE-CTC. In this study, a custom-made anthropomorphic colon phantom, which was filled with simulated tagged materials by non-ionic iodinated contrast agent (Omnipaque iohexol, GE Healthcare), was scanned by a dual-source CT scanner (SOMATON Definition Flash, Siemens Healthcare) at two photon energies: 80 kVp and 140 kVp with nine different tube current settings ranging from 12 to 74 mAs for 140 kVp, and then reconstructed by soft-tissue reconstruction kernel (B30f). The DE-CTC images were subjected to a low-dose DE-EC scheme. First, our image-space DE-CTC denoising filter was applied for reduction of image noise. Then, the noise-reduced images were processed by a virtual lumen tagging method for reduction of partial volume effect and tagging inhomogeneity. The results were compared with the registered CTC images of native phantom without fillings. Preliminary results showed that our low-dose DE-EC scheme achieved the cleansing ratios, defined by the proportion of the cleansed voxels in the tagging mask, between 93.18% (12 mAs) and 96.62% (74 mAs). Also, the soft-tissue preservation ratios, defined by the proportion of the persevered voxels in the soft-tissue mask, were maintained in the range between 94.67% and 96.41%.

  3. Automated aortic calcification detection in low-dose chest CT images

    NASA Astrophysics Data System (ADS)

    Xie, Yiting; Htwe, Yu Maw; Padgett, Jennifer; Henschke, Claudia; Yankelevitz, David; Reeves, Anthony P.

    2014-03-01

    The extent of aortic calcification has been shown to be a risk indicator for vascular events including cardiac events. We have developed a fully automated computer algorithm to segment and measure aortic calcification in low-dose noncontrast, non-ECG gated, chest CT scans. The algorithm first segments the aorta using a pre-computed Anatomy Label Map (ALM). Then based on the segmented aorta, aortic calcification is detected and measured in terms of the Agatston score, mass score, and volume score. The automated scores are compared with reference scores obtained from manual markings. For aorta segmentation, the aorta is modeled as a series of discrete overlapping cylinders and the aortic centerline is determined using a cylinder-tracking algorithm. Then the aortic surface location is detected using the centerline and a triangular mesh model. The segmented aorta is used as a mask for the detection of aortic calcification. For calcification detection, the image is first filtered, then an elevated threshold of 160 Hounsfield units (HU) is used within the aorta mask region to reduce the effect of noise in low-dose scans, and finally non-aortic calcification voxels (bony structures, calcification in other organs) are eliminated. The remaining candidates are considered as true aortic calcification. The computer algorithm was evaluated on 45 low-dose non-contrast CT scans. Using linear regression, the automated Agatston score is 98.42% correlated with the reference Agatston score. The automated mass and volume score is respectively 98.46% and 98.28% correlated with the reference mass and volume score.

  4. Improving Low-dose Cardiac CT Images based on 3D Sparse Representation

    PubMed Central

    Shi, Luyao; Hu, Yining; Chen, Yang; Yin, Xindao; Shu, Huazhong; Luo, Limin; Coatrieux, Jean-Louis

    2016-01-01

    Cardiac computed tomography (CCT) is a reliable and accurate tool for diagnosis of coronary artery diseases and is also frequently used in surgery guidance. Low-dose scans should be considered in order to alleviate the harm to patients caused by X-ray radiation. However, low dose CT (LDCT) images tend to be degraded by quantum noise and streak artifacts. In order to improve the cardiac LDCT image quality, a 3D sparse representation-based processing (3D SR) is proposed by exploiting the sparsity and regularity of 3D anatomical features in CCT. The proposed method was evaluated by a clinical study of 14 patients. The performance of the proposed method was compared to the 2D spares representation-based processing (2D SR) and the state-of-the-art noise reduction algorithm BM4D. The visual assessment, quantitative assessment and qualitative assessment results show that the proposed approach can lead to effective noise/artifact suppression and detail preservation. Compared to the other two tested methods, 3D SR method can obtain results with image quality most close to the reference standard dose CT (SDCT) images. PMID:26980176

  5. Improving Low-dose Cardiac CT Images based on 3D Sparse Representation

    NASA Astrophysics Data System (ADS)

    Shi, Luyao; Hu, Yining; Chen, Yang; Yin, Xindao; Shu, Huazhong; Luo, Limin; Coatrieux, Jean-Louis

    2016-03-01

    Cardiac computed tomography (CCT) is a reliable and accurate tool for diagnosis of coronary artery diseases and is also frequently used in surgery guidance. Low-dose scans should be considered in order to alleviate the harm to patients caused by X-ray radiation. However, low dose CT (LDCT) images tend to be degraded by quantum noise and streak artifacts. In order to improve the cardiac LDCT image quality, a 3D sparse representation-based processing (3D SR) is proposed by exploiting the sparsity and regularity of 3D anatomical features in CCT. The proposed method was evaluated by a clinical study of 14 patients. The performance of the proposed method was compared to the 2D spares representation-based processing (2D SR) and the state-of-the-art noise reduction algorithm BM4D. The visual assessment, quantitative assessment and qualitative assessment results show that the proposed approach can lead to effective noise/artifact suppression and detail preservation. Compared to the other two tested methods, 3D SR method can obtain results with image quality most close to the reference standard dose CT (SDCT) images.

  6. Effects of sparse sampling schemes on image quality in low-dose CT

    SciTech Connect

    Abbas, Sajid; Lee, Taewon; Cho, Seungryong; Shin, Sukyoung; Lee, Rena

    2013-11-15

    Purpose: Various scanning methods and image reconstruction algorithms are actively investigated for low-dose computed tomography (CT) that can potentially reduce a health-risk related to radiation dose. Particularly, compressive-sensing (CS) based algorithms have been successfully developed for reconstructing images from sparsely sampled data. Although these algorithms have shown promises in low-dose CT, it has not been studied how sparse sampling schemes affect image quality in CS-based image reconstruction. In this work, the authors present several sparse-sampling schemes for low-dose CT, quantitatively analyze their data property, and compare effects of the sampling schemes on the image quality.Methods: Data properties of several sampling schemes are analyzed with respect to the CS-based image reconstruction using two measures: sampling density and data incoherence. The authors present five different sparse sampling schemes, and simulated those schemes to achieve a targeted dose reduction. Dose reduction factors of about 75% and 87.5%, compared to a conventional scan, were tested. A fully sampled circular cone-beam CT data set was used as a reference, and sparse sampling has been realized numerically based on the CBCT data.Results: It is found that both sampling density and data incoherence affect the image quality in the CS-based reconstruction. Among the sampling schemes the authors investigated, the sparse-view, many-view undersampling (MVUS)-fine, and MVUS-moving cases have shown promising results. These sampling schemes produced images with similar image quality compared to the reference image and their structure similarity index values were higher than 0.92 in the mouse head scan with 75% dose reduction.Conclusions: The authors found that in CS-based image reconstructions both sampling density and data incoherence affect the image quality, and suggest that a sampling scheme should be devised and optimized by use of these indicators. With this strategic

  7. Evaluation of a low-dose/slow-rotating SPECT-CT system

    NASA Astrophysics Data System (ADS)

    Hamann, M.; Aldridge, M.; Dickson, J.; Endozo, R.; Lozhkin, K.; Hutton, B. F.

    2008-05-01

    The 4-slice CT that forms part of the GE Infinia Hawkeye-4 SPECT-CT scanner (Hawkeye) is evaluated against the diagnostic 16-slice CT that is incorporated in the GE Discovery ST PET-CT system (DST). The x-ray tube of the slow-rotating Hawkeye system (23 s/rotation) operates at approximately a third of the dose of diagnostic systems as used for conventional diagnostic imaging. Image reconstruction is optimized for low noise. High-contrast spatial resolution significantly falls behind diagnostic figures: the average of MTF50 and MTF10 (resolution where the MTF has fallen to 50% and 10%) is 2.8 ± 0.1 cm-1 for Hawkeye and 5.3 ± 0.1 cm-1 for the DST (standard reconstruction filters). Resolution in the direction of the couch movement (z coordinate) is governed by the fixed Hawkeye slice width of 5 mm. Reconstruction accuracy is found to be increased by reducing the default z increment from 4.4 mm to 2.2 mm. Low-contrast object detectability is superior compared with diagnostic systems operating in the Hawkeye dose range. In the diagnostic dose regime, however, small low-contrast details remain visible in DST that are not detectable with Hawkeye. Although not of diagnostic quality, the low-dose Hawkeye provides appropriate data for SPECT attenuation correction and anatomical localization capability. For more information on this article, see medicalphysicsweb.org

  8. Automatic coronary calcium scoring in low-dose non-ECG-synchronized thoracic CT scans

    NASA Astrophysics Data System (ADS)

    Isgum, Ivana; Prokop, Mathias; Jacobs, Peter C.; Gondrie, Martijn J.; Mali, Willem P. Th. M.; Viergever, Max A.; van Ginneken, Bram

    2010-03-01

    This work presents a system for automatic coronary calcium scoring and cardiovascular risk stratification in thoracic CT scans. Data was collected from a Dutch-Belgian lung cancer screening trial. In 121 low-dose, non-ECG synchronized, non-contrast enhanced thoracic CT scans an expert scored coronary calcifications manually. A key element of the proposed algorithm is that the approximate position of the coronary arteries was inferred with a probabilistic coronary calcium atlas. This atlas was created with atlas-based segmentation from 51 scans and their manually identified calcifications, and was registered to each unseen test scan. In the test scans all objects with density above 130 HU were considered candidates that could represent coronary calcifications. A statistical pattern recognition system was designed to classify these candidates using features that encode their spatial position relative to the inferred position of the coronaries obtained from the atlas registration. In addition, size and texture features were computed for all candidates. Two consecutive classifiers were used to label each candidate. The system was trained with 35 and tested with another 35 scans. The detected calcifications were quantified and cardiovascular risk was determined for each subject. The system detected 71% of coronary calcifications with an average of 0.9 false positive objects per scan. Cardiovascular risk category was correctly assigned to 29 out of 35 subjects (83%). Five scans (14%) were one category off, and only one scan (3%) was two categories off. We conclude that automatic assessment of the cardiovascular risk from low-dose, non-ECG synchronized thoracic CT scans appears feasible.

  9. Sinogram restoration for ultra-low-dose x-ray multi-slice helical CT by nonparametric regression

    NASA Astrophysics Data System (ADS)

    Jiang, Lu; Siddiqui, Khan; Zhu, Bin; Tao, Yang; Siegel, Eliot

    2007-03-01

    During the last decade, x-ray computed tomography (CT) has been applied to screen large asymptomatic smoking and nonsmoking populations for early lung cancer detection. Because a larger population will be involved in such screening exams, more and more attention has been paid to studying low-dose, even ultra-low-dose x-ray CT. However, reducing CT radiation exposure will increase noise level in the sinogram, thereby degrading the quality of reconstructed CT images as well as causing more streak artifacts near the apices of the lung. Thus, how to reduce the noise levels and streak artifacts in the low-dose CT images is becoming a meaningful topic. Since multi-slice helical CT has replaced conventional stop-and-shoot CT in many clinical applications, this research mainly focused on the noise reduction issue in multi-slice helical CT. The experiment data were provided by Siemens SOMATOM Sensation 16-Slice helical CT. It included both conventional CT data acquired under 120 kvp voltage and 119 mA current and ultra-low-dose CT data acquired under 120 kvp and 10 mA protocols. All other settings are the same as that of conventional CT. In this paper, a nonparametric smoothing method with thin plate smoothing splines and the roughness penalty was proposed to restore the ultra-low-dose CT raw data. Each projection frame was firstly divided into blocks, and then the 2D data in each block was fitted to a thin-plate smoothing splines' surface via minimizing a roughness-penalized least squares objective function. By doing so, the noise in each ultra-low-dose CT projection was reduced by leveraging the information contained not only within each individual projection profile, but also among nearby profiles. Finally the restored ultra-low-dose projection data were fed into standard filtered back projection (FBP) algorithm to reconstruct CT images. The rebuilt results as well as the comparison between proposed approach and traditional method were given in the results and

  10. Functional phase-correlated micro-CT imaging of small rodents with low dose

    NASA Astrophysics Data System (ADS)

    Sawall, Stefan; Bergner, Frank; Hess, Andreas; Lapp, Robert; Mronz, Markus; Karolczak, Marek; Kachelriess, Marc

    2011-03-01

    Functional imaging of an animals thoracic region requires cardiac and respiratory gating. The information on respiratory motion and ECG required for double-gating are extracted from the rawdata and used to select the projections appropriate for a given motion phase. A conventional phase-correlated reconstruction (PC) therefore uses only a small amount of the total projections acquired. Thus the resulting images comprise a high noise level unless acquired with very high dose, and streak artifacts may occur due to the sparse angular sampling. Here, we are aiming at getting high fidelity images even for relatively low dose values. To overcome these issues we implemented an iterative reconstruction method encompassing a five-dimensional (spatial, cardiac-temporal, respiratory-temporal) edge-preserving filter. This new phase-correlated low-dose (LDPC) reconstruction method is evaluated using retrospectively-gated, contrast-enhanced micro CT data of mice. The scans performed comprise 7200 projections within 10 rotations over 5 minutes. A tube voltage of 65 kV was used resulting in an administered dose of about 500 mGy. 20 respiratory phases and 10 cardiac phases are reconstructed. Using LDPC reconstruction the image noise is typically reduced by a factor of about six and artifacts are almost removed. Reducing the number of projections available for reconstruction shows that we can get comparable image quality with only 200 mGy. LDPC enables high fidelity low-dose double-gated imaging of free breathing rodents without compromises in image quality. Compared to PC image noise is significantly reduced with LDPC and the administered dose can be reduced accordingly.

  11. Synthetic CT: Simulating low dose single and dual energy protocols from a dual energy scan

    SciTech Connect

    Wang, Adam S.; Pelc, Norbert J.

    2011-10-15

    Purpose: The choice of CT protocol can greatly impact patient dose and image quality. Since acquiring multiple scans at different techniques on a given patient is undesirable, the ability to predict image quality changes starting from a high quality exam can be quite useful. While existing methods allow one to generate simulated images of lower exposure (mAs) from an acquired CT exam, the authors present and validate a new method called synthetic CT that can generate realistic images of a patient at arbitrary low dose protocols (kVp, mAs, and filtration) for both single and dual energy scans. Methods: The synthetic CT algorithm is derived by carefully ensuring that the expected signal and noise are accurate for the simulated protocol. The method relies on the observation that the material decomposition from a dual energy CT scan allows the transmission of an arbitrary spectrum to be predicted. It requires an initial dual energy scan of the patient to either synthesize raw projections of a single energy scan or synthesize the material decompositions of a dual energy scan. The initial dual energy scan contributes inherent noise to the synthesized projections that must be accounted for before adding more noise to simulate low dose protocols. Therefore, synthetic CT is subject to the constraint that the synthesized data have noise greater than the inherent noise. The authors experimentally validated the synthetic CT algorithm across a range of protocols using a dual energy scan of an acrylic phantom with solutions of different iodine concentrations. An initial 80/140 kVp dual energy scan of the phantom provided the material decomposition necessary to synthesize images at 100 kVp and at 120 kVp, across a range of mAs values. They compared these synthesized single energy scans of the phantom to actual scans at the same protocols. Furthermore, material decompositions of a 100/120 kVp dual energy scan are synthesized by adding correlated noise to the initial material

  12. Effect of low-dose CT and iterative reconstruction on trabecular bone microstructure assessment

    NASA Astrophysics Data System (ADS)

    Kopp, Felix K.; Baum, Thomas; Nasirudin, Radin A.; Mei, Kai; Garcia, Eduardo G.; Burgkart, Rainer; Rummeny, Ernst J.; Bauer, Jan S.; Noël, Peter B.

    2016-03-01

    The trabecular bone microstructure is an important factor in the development of osteoporosis. It is well known that its deterioration is one effect when osteoporosis occurs. Previous research showed that the analysis of trabecular bone microstructure enables more precise diagnoses of osteoporosis compared to a sole measurement of the mineral density. Microstructure parameters are assessed on volumetric images of the bone acquired either with high-resolution magnetic resonance imaging, high-resolution peripheral quantitative computed tomography or high-resolution computed tomography (CT), with only CT being applicable to the spine, which is one of clinically most relevant fracture sites. However, due to the high radiation exposure for imaging the whole spine these measurements are not applicable in current clinical routine. In this work, twelve vertebrae from three different donors were scanned with standard and low radiation dose. Trabecular bone microstructure parameters were assessed for CT images reconstructed with statistical iterative reconstruction (SIR) and analytical filtered backprojection (FBP). The resulting structure parameters were correlated to the biomechanically determined fracture load of each vertebra. Microstructure parameters assessed for low-dose data reconstructed with SIR significantly correlated with fracture loads as well as parameters assessed for standard-dose data reconstructed with FBP. Ideal results were achieved with low to zero regularization strength yielding microstructure parameters not significantly different from those assessed for standard-dose FPB data. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods.

  13. Implemented myeloma management with whole-body low-dose CT scan: a real life experience.

    PubMed

    Mangiacavalli, Silvia; Pezzatti, Sara; Rossini, Fausto; Doni, Elisa; Cocito, Federica; Bolis, Silvia; Corso, Alessandro

    2016-07-01

    A total of 318 consecutive myeloma patients underwent whole-body low-dose CT scan (WBLDCT) at baseline and during follow-up as a radiological assessment of lytic lesions in place of skeletal X-ray survey. After WBLDCT baseline assessment, 60% had bone involvement. The presence of lytic lesions represented the only met CRAB (hyperCalcaemia, Renal insufficiency, Anaemia, Bone lesions) criteria in 29% of patients. Patients presenting with extramedullary masses were 10%. Radiological progression was documented in 9% of the population with available follow-up. Additional pathological incidental findings were detected in 28 patients (14.5%), most located in the chest region (68%). In conclusion, our real-life data shows that WBLDCT scan represents a reliable imaging tool for decision-making process for multiple myeloma management in different disease phases, providing significant additional information on the presence of soft tissues plasmacytomas detection as well as the presence of pathological incidental findings. PMID:26788613

  14. Low-dose CT reconstruction via edge-preserving total variation regularization.

    PubMed

    Tian, Zhen; Jia, Xun; Yuan, Kehong; Pan, Tinsu; Jiang, Steve B

    2011-09-21

    High radiation dose in computed tomography (CT) scans increases the lifetime risk of cancer and has become a major clinical concern. Recently, iterative reconstruction algorithms with total variation (TV) regularization have been developed to reconstruct CT images from highly undersampled data acquired at low mAs levels in order to reduce the imaging dose. Nonetheless, the low-contrast structures tend to be smoothed out by the TV regularization, posing a great challenge for the TV method. To solve this problem, in this work we develop an iterative CT reconstruction algorithm with edge-preserving TV (EPTV) regularization to reconstruct CT images from highly undersampled data obtained at low mAs levels. The CT image is reconstructed by minimizing energy consisting of an EPTV norm and a data fidelity term posed by the x-ray projections. The EPTV term is proposed to preferentially perform smoothing only on the non-edge part of the image in order to better preserve the edges, which is realized by introducing a penalty weight to the original TV norm. During the reconstruction process, the pixels at the edges would be gradually identified and given low penalty weight. Our iterative algorithm is implemented on graphics processing unit to improve its speed. We test our reconstruction algorithm on a digital NURBS-based cardiac-troso phantom, a physical chest phantom and a Catphan phantom. Reconstruction results from a conventional filtered backprojection (FBP) algorithm and a TV regularization method without edge-preserving penalty are also presented for comparison purposes. The experimental results illustrate that both the TV-based algorithm and our EPTV algorithm outperform the conventional FBP algorithm in suppressing the streaking artifacts and image noise under a low-dose context. Our edge-preserving algorithm is superior to the TV-based algorithm in that it can preserve more information of low-contrast structures and therefore maintain acceptable spatial resolution

  15. Heart region segmentation from low-dose CT scans: an anatomy based approach

    NASA Astrophysics Data System (ADS)

    Reeves, Anthony P.; Biancardi, Alberto M.; Yankelevitz, David F.; Cham, Matthew D.; Henschke, Claudia I.

    2012-02-01

    Cardiovascular disease is a leading cause of death in developed countries. The concurrent detection of heart diseases during low-dose whole-lung CT scans (LDCT), typically performed as part of a screening protocol, hinges on the accurate quantification of coronary calcification. The creation of fully automated methods is ideal as complete manual evaluation is imprecise, operator dependent, time consuming and thus costly. The technical challenges posed by LDCT scans in this context are mainly twofold. First, there is a high level image noise arising from the low radiation dose technique. Additionally, there is a variable amount of cardiac motion blurring due to the lack of electrocardiographic gating and the fact that heart rates differ between human subjects. As a consequence, the reliable segmentation of the heart, the first stage toward the implementation of morphologic heart abnormality detection, is also quite challenging. An automated computer method based on a sequential labeling of major organs and determination of anatomical landmarks has been evaluated on a public database of LDCT images. The novel algorithm builds from a robust segmentation of the bones and airways and embodies a stepwise refinement starting at the top of the lungs where image noise is at its lowest and where the carina provides a good calibration landmark. The segmentation is completed at the inferior wall of the heart where extensive image noise is accommodated. This method is based on the geometry of human anatomy and does not involve training through manual markings. Using visual inspection by an expert reader as a gold standard, the algorithm achieved successful heart and major vessel segmentation in 42 of 45 low-dose CT images. In the 3 remaining cases, the cardiac base was over segmented due to incorrect hemidiaphragm localization.

  16. Optimization of SPECT-CT Hybrid Imaging Using Iterative Image Reconstruction for Low-Dose CT: A Phantom Study

    PubMed Central

    Grosser, Oliver S.; Kupitz, Dennis; Ruf, Juri; Czuczwara, Damian; Steffen, Ingo G.; Furth, Christian; Thormann, Markus; Loewenthal, David; Ricke, Jens; Amthauer, Holger

    2015-01-01

    Background Hybrid imaging combines nuclear medicine imaging such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) with computed tomography (CT). Through this hybrid design, scanned patients accumulate radiation exposure from both applications. Imaging modalities have been the subject of long-term optimization efforts, focusing on diagnostic applications. It was the aim of this study to investigate the influence of an iterative CT image reconstruction algorithm (ASIR) on the image quality of the low-dose CT images. Methodology/Principal Findings Examinations were performed with a SPECT-CT scanner with standardized CT and SPECT-phantom geometries and CT protocols with systematically reduced X-ray tube currents. Analyses included image quality with respect to photon flux. Results were compared to the standard FBP reconstructed images. The general impact of the CT-based attenuation maps used during SPECT reconstruction was examined for two SPECT phantoms. Using ASIR for image reconstructions, image noise was reduced compared to FBP reconstructions for the same X-ray tube current. The Hounsfield unit (HU) values reconstructed by ASIR were correlated to the FBP HU values(R2 ≥ 0.88) and the contrast-to-noise ratio (CNR) was improved by ASIR. However, for a phantom with increased attenuation, the HU values shifted for low X-ray tube currents I ≤ 60 mA (p ≤ 0.04). In addition, the shift of the HU values was observed within the attenuation corrected SPECT images for very low X-ray tube currents (I ≤ 20 mA, p ≤ 0.001). Conclusion/Significance In general, the decrease in X-ray tube current up to 30 mA in combination with ASIR led to a reduction of CT-related radiation exposure without a significant decrease in image quality. PMID:26390216

  17. Adaptive Tensor-Based Principal Component Analysis for Low-Dose CT Image Denoising

    PubMed Central

    Ai, Danni; Yang, Jian; Fan, Jingfan; Cong, Weijian; Wang, Yongtian

    2015-01-01

    Computed tomography (CT) has a revolutionized diagnostic radiology but involves large radiation doses that directly impact image quality. In this paper, we propose adaptive tensor-based principal component analysis (AT-PCA) algorithm for low-dose CT image denoising. Pixels in the image are presented by their nearby neighbors, and are modeled as a patch. Adaptive searching windows are calculated to find similar patches as training groups for further processing. Tensor-based PCA is used to obtain transformation matrices, and coefficients are sequentially shrunk by the linear minimum mean square error. Reconstructed patches are obtained, and a denoised image is finally achieved by aggregating all of these patches. The experimental results of the standard test image show that the best results are obtained with two denoising rounds according to six quantitative measures. For the experiment on the clinical images, the proposed AT-PCA method can suppress the noise, enhance the edge, and improve the image quality more effectively than NLM and KSVD denoising methods. PMID:25993566

  18. Low-dose CT statistical iterative reconstruction via modified MRF regularization.

    PubMed

    Shangguan, Hong; Zhang, Quan; Liu, Yi; Cui, Xueying; Bai, Yunjiao; Gui, Zhiguo

    2016-01-01

    It is desirable to reduce the excessive radiation exposure to patients in repeated medical CT applications. One of the most effective ways is to reduce the X-ray tube current (mAs) or tube voltage (kVp). However, it is difficult to achieve accurate reconstruction from the noisy measurements. Compared with the conventional filtered back-projection (FBP) algorithm leading to the excessive noise in the reconstructed images, the approaches using statistical iterative reconstruction (SIR) with low mAs show greater image quality. To eliminate the undesired artifacts and improve reconstruction quality, we proposed, in this work, an improved SIR algorithm for low-dose CT reconstruction, constrained by a modified Markov random field (MRF) regularization. Specifically, the edge-preserving total generalized variation (TGV), which is a generalization of total variation (TV) and can measure image characteristics up to a certain degree of differentiation, was introduced to modify the MRF regularization. In addition, a modified alternating iterative algorithm was utilized to optimize the cost function. Experimental results demonstrated that images reconstructed by the proposed method could not only generate high accuracy and resolution properties, but also ensure a higher peak signal-to-noise ratio (PSNR) in comparison with those using existing methods. PMID:26542474

  19. Deformable 3D-2D registration for CT and its application to low dose tomographic fluoroscopy

    NASA Astrophysics Data System (ADS)

    Flach, Barbara; Brehm, Marcus; Sawall, Stefan; Kachelrieß, Marc

    2014-12-01

    Many applications in medical imaging include image registration for matching of images from the same or different modalities. In the case of full data sampling, the respective reconstructed images are usually of such a good image quality that standard deformable volume-to-volume (3D-3D) registration approaches can be applied. But research in temporal-correlated image reconstruction and dose reductions increases the number of cases where rawdata are available from only few projection angles. Here, deteriorated image quality leads to non-acceptable deformable volume-to-volume registration results. Therefore a registration approach is required that is robust against a decreasing number of projections defining the target position. We propose a deformable volume-to-rawdata (3D-2D) registration method that aims at finding a displacement vector field maximizing the alignment of a CT volume and the acquired rawdata based on the sum of squared differences in rawdata domain. The registration is constrained by a regularization term in accordance with a fluid-based diffusion. Both cost function components, the rawdata fidelity and the regularization term, are optimized in an alternating manner. The matching criterion is optimized by a conjugate gradient descent for nonlinear functions, while the regularization is realized by convolution of the vector fields with Gaussian kernels. We validate the proposed method and compare it to the demons algorithm, a well-known 3D-3D registration method. The comparison is done for a range of 4-60 target projections using datasets from low dose tomographic fluoroscopy as an application example. The results show a high correlation to the ground truth target position without introducing artifacts even in the case of very few projections. In particular the matching in the rawdata domain is improved compared to the 3D-3D registration for the investigated range. The proposed volume-to-rawdata registration increases the robustness regarding sparse

  20. Deformable 3D-2D registration for CT and its application to low dose tomographic fluoroscopy.

    PubMed

    Flach, Barbara; Brehm, Marcus; Sawall, Stefan; Kachelrieß, Marc

    2014-12-21

    Many applications in medical imaging include image registration for matching of images from the same or different modalities. In the case of full data sampling, the respective reconstructed images are usually of such a good image quality that standard deformable volume-to-volume (3D-3D) registration approaches can be applied. But research in temporal-correlated image reconstruction and dose reductions increases the number of cases where rawdata are available from only few projection angles. Here, deteriorated image quality leads to non-acceptable deformable volume-to-volume registration results. Therefore a registration approach is required that is robust against a decreasing number of projections defining the target position. We propose a deformable volume-to-rawdata (3D-2D) registration method that aims at finding a displacement vector field maximizing the alignment of a CT volume and the acquired rawdata based on the sum of squared differences in rawdata domain. The registration is constrained by a regularization term in accordance with a fluid-based diffusion. Both cost function components, the rawdata fidelity and the regularization term, are optimized in an alternating manner. The matching criterion is optimized by a conjugate gradient descent for nonlinear functions, while the regularization is realized by convolution of the vector fields with Gaussian kernels. We validate the proposed method and compare it to the demons algorithm, a well-known 3D-3D registration method. The comparison is done for a range of 4-60 target projections using datasets from low dose tomographic fluoroscopy as an application example. The results show a high correlation to the ground truth target position without introducing artifacts even in the case of very few projections. In particular the matching in the rawdata domain is improved compared to the 3D-3D registration for the investigated range. The proposed volume-to-rawdata registration increases the robustness regarding sparse

  1. Assessment of Bowel Wall Enhancement for the Diagnosis of Intestinal Ischemia in Patients with Small Bowel Obstruction: Value of Adding Unenhanced CT to Contrast-enhanced CT.

    PubMed

    Chuong, Anh Minh; Corno, Lucie; Beaussier, Hélène; Boulay-Coletta, Isabelle; Millet, Ingrid; Hodel, Jérôme; Taourel, Patrice; Chatellier, Gilles; Zins, Marc

    2016-07-01

    Purpose To determine whether adding unenhanced computed tomography (CT) to contrast material-enhanced CT improves the diagnostic performance of decreased bowel wall enhancement as a sign of ischemia complicating mechanical small bowel obstruction (SBO). Materials and Methods This retrospective study was approved by the institutional review board, which waived the requirement for informed consent. Two gastrointestinal radiologists independently performed retrospective assessments of 164 unenhanced and contrast-enhanced CT studies from 158 consecutive patients (mean age, 71.2 years) with mechanical SBO. The reference standard was the intraoperative and/or histologic diagnosis (in 80 cases) or results from clinical follow-up in patients who did not undergo surgery (84 cases). Decreased bowel wall enhancement was evaluated with contrast-enhanced images then and both unenhanced and contrast-enhanced images 1 month later. Diagnostic performance of decreased bowel wall enhancement and confidence in the diagnosis were compared between the two readings by using McNemar and Wilcoxon signed rank tests. Interobserver agreement was assessed by using κ statistics and compared with bootstrapping. Results Ischemia was diagnosed in 41 of 164 (25%) episodes of SBO. For both observers, adding unenhanced images improved decreased bowel wall enhancement sensitivity (observer 1: 46.3% [19 of 41] vs 65.8% [27 of 41], P = .02; observer 2: 56.1% [23 of 41] vs 63.4% [26 of 41], P = .45), Youden index (from 0.41 to 0.58 for observer 1 and from 0.42 to 0.61 for observer 2), and confidence score (P < .001 for both). Specificity significantly increased for observer 2 (84.5% [104 of 123] vs 94.3% [116 of 123], P = .002), and interobserver agreement significantly increased, from moderate (κ = 0.48) to excellent (κ = 0.89; P < .0001). Conclusion Adding unenhanced CT to contrast-enhanced CT improved the sensitivity, diagnostic confidence, and interobserver agreement of the diagnosis of ischemia

  2. Texture-based CAD improves diagnosis for low-dose CT colonography

    NASA Astrophysics Data System (ADS)

    Liang, Zhengrong; Cohen, Harris; Posniak, Erica; Fiore, Eddie; Wang, Zigang; Li, Bin; Andersen, Joseph; Harrington, Donald

    2008-03-01

    Computed tomography (CT)-based virtual colonoscopy or CT colonography (CTC) currently utilizes oral contrast solutions to tag the colonic fluid and possibly residual stool for differentiation from the colon wall and polyps. The enhanced image density of the tagged colonic materials causes a significant partial volume (PV) effect into the colon wall as well as the lumen space (filled with air or CO II). The PV effect on the colon wall can "bury" polyps of size as large as 5mm by increasing their image densities to a noticeable level, resulting in false negatives. It can also create false positives when PV effect goes into the lumen space. We have been modeling the PV effect for mixture-based image segmentation and developing text-based computer-aided detection of polyp (CADpolyp) by utilizing the PV mixture-based image segmentation. This work presents some preliminary results of developing and applying texture-based CADpolyp technique to low-dose CTC studies. A total of 114 studies of asymptomatic patients older than 50, who underwent CTC and then optical colonoscopy (OC) on the same day, were selected from a database, which was accumulated in the past decade and contains various bowel preparations and CT scanning protocols. The participating radiologists found ten polyps of greater than 5 mm from a total of 16 OC proved polyps, i.e., a detection sensitivity of 63%. They scored 23 false positives from the database, i.e., a 20% false positive rate. Approximately 70% of the datasets were marked as imperfect bowel cleansing and/or presence of image artifacts. The impact of imperfect bowel cleansing and image artifacts on VC performance is significant. The texture-based CADpolyp detected all the polyps with an average of 2.68 false positives per patient. This indicates that texture-based CADpolyp can improve the CTC performance in the cases of imperfect cleansed bowels and presence of image artifacts.

  3. Anatomical-based partial volume correction for low-dose dedicated cardiac SPECT/CT.

    PubMed

    Liu, Hui; Chan, Chung; Grobshtein, Yariv; Ma, Tianyu; Liu, Yaqiang; Wang, Shi; Stacy, Mitchel R; Sinusas, Albert J; Liu, Chi

    2015-09-01

    Due to the limited spatial resolution, partial volume effect has been a major degrading factor on quantitative accuracy in emission tomography systems. This study aims to investigate the performance of several anatomical-based partial volume correction (PVC) methods for a dedicated cardiac SPECT/CT system (GE Discovery NM/CT 570c) with focused field-of-view over a clinically relevant range of high and low count levels for two different radiotracer distributions. These PVC methods include perturbation geometry transfer matrix (pGTM), pGTM followed by multi-target correction (MTC), pGTM with known concentration in blood pool, the former followed by MTC and our newly proposed methods, which perform the MTC method iteratively, where the mean values in all regions are estimated and updated by the MTC-corrected images each time in the iterative process. The NCAT phantom was simulated for cardiovascular imaging with (99m)Tc-tetrofosmin, a myocardial perfusion agent, and (99m)Tc-red blood cell (RBC), a pure intravascular imaging agent. Images were acquired at six different count levels to investigate the performance of PVC methods in both high and low count levels for low-dose applications. We performed two large animal in vivo cardiac imaging experiments following injection of (99m)Tc-RBC for evaluation of intramyocardial blood volume (IMBV). The simulation results showed our proposed iterative methods provide superior performance than other existing PVC methods in terms of image quality, quantitative accuracy, and reproducibility (standard deviation), particularly for low-count data. The iterative approaches are robust for both (99m)Tc-tetrofosmin perfusion imaging and (99m)Tc-RBC imaging of IMBV and blood pool activity even at low count levels. The animal study results indicated the effectiveness of PVC to correct the overestimation of IMBV due to blood pool contamination. In conclusion, the iterative PVC methods can achieve more accurate quantification, particularly

  4. Anatomical-based partial volume correction for low-dose dedicated cardiac SPECT/CT

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Chan, Chung; Grobshtein, Yariv; Ma, Tianyu; Liu, Yaqiang; Wang, Shi; Stacy, Mitchel R.; Sinusas, Albert J.; Liu, Chi

    2015-09-01

    Due to the limited spatial resolution, partial volume effect has been a major degrading factor on quantitative accuracy in emission tomography systems. This study aims to investigate the performance of several anatomical-based partial volume correction (PVC) methods for a dedicated cardiac SPECT/CT system (GE Discovery NM/CT 570c) with focused field-of-view over a clinically relevant range of high and low count levels for two different radiotracer distributions. These PVC methods include perturbation geometry transfer matrix (pGTM), pGTM followed by multi-target correction (MTC), pGTM with known concentration in blood pool, the former followed by MTC and our newly proposed methods, which perform the MTC method iteratively, where the mean values in all regions are estimated and updated by the MTC-corrected images each time in the iterative process. The NCAT phantom was simulated for cardiovascular imaging with 99mTc-tetrofosmin, a myocardial perfusion agent, and 99mTc-red blood cell (RBC), a pure intravascular imaging agent. Images were acquired at six different count levels to investigate the performance of PVC methods in both high and low count levels for low-dose applications. We performed two large animal in vivo cardiac imaging experiments following injection of 99mTc-RBC for evaluation of intramyocardial blood volume (IMBV). The simulation results showed our proposed iterative methods provide superior performance than other existing PVC methods in terms of image quality, quantitative accuracy, and reproducibility (standard deviation), particularly for low-count data. The iterative approaches are robust for both 99mTc-tetrofosmin perfusion imaging and 99mTc-RBC imaging of IMBV and blood pool activity even at low count levels. The animal study results indicated the effectiveness of PVC to correct the overestimation of IMBV due to blood pool contamination. In conclusion, the iterative PVC methods can achieve more accurate quantification, particularly for low

  5. Segmentation of the whole breast from low-dose chest CT images

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Salvatore, Mary; Yankelevitz, David F.; Henschke, Claudia I.; Reeves, Anthony P.

    2015-03-01

    The segmentation of whole breast serves as the first step towards automated breast lesion detection. It is also necessary for automatically assessing the breast density, which is considered to be an important risk factor for breast cancer. In this paper we present a fully automated algorithm to segment the whole breast in low-dose chest CT images (LDCT), which has been recommended as an annual lung cancer screening test. The automated whole breast segmentation and potential breast density readings as well as lesion detection in LDCT will provide useful information for women who have received LDCT screening, especially the ones who have not undergone mammographic screening, by providing them additional risk indicators for breast cancer with no additional radiation exposure. The two main challenges to be addressed are significant range of variations in terms of the shape and location of the breast in LDCT and the separation of pectoral muscles from the glandular tissues. The presented algorithm achieves robust whole breast segmentation using an anatomy directed rule-based method. The evaluation is performed on 20 LDCT scans by comparing the segmentation with ground truth manually annotated by a radiologist on one axial slice and two sagittal slices for each scan. The resulting average Dice coefficient is 0.880 with a standard deviation of 0.058, demonstrating that the automated segmentation algorithm achieves results consistent with manual annotations of a radiologist.

  6. Optimized Parallelization for Nonlocal Means Based Low Dose CT Image Processing

    PubMed Central

    Zhang, Libo; Yang, Benqiang; Zhuang, Zhikun; Hu, Yining; Chen, Yang; Luo, Limin; Shu, Huazhong

    2015-01-01

    Low dose CT (LDCT) images are often significantly degraded by severely increased mottled noise/artifacts, which can lead to lowered diagnostic accuracy in clinic. The nonlocal means (NLM) filtering can effectively remove mottled noise/artifacts by utilizing large-scale patch similarity information in LDCT images. But the NLM filtering application in LDCT imaging also requires high computation cost because intensive patch similarity calculation within a large searching window is often required to be used to include enough structure-similarity information for noise/artifact suppression. To improve its clinical feasibility, in this study we further optimize the parallelization of NLM filtering by avoiding the repeated computation with the row-wise intensity calculation and the symmetry weight calculation. The shared memory with fast I/O speed is also used in row-wise intensity calculation for the proposed method. Quantitative experiment demonstrates that significant acceleration can be achieved with respect to the traditional straight pixel-wise parallelization. PMID:26078781

  7. Quantification of pulmonary vessel diameter in low-dose CT images

    NASA Astrophysics Data System (ADS)

    Rudyanto, Rina D.; Ortiz de Solórzano, Carlos; Muñoz-Barrutia, Arrate

    2015-03-01

    Accurate quantification of vessel diameter in low-dose Computer Tomography (CT) images is important to study pulmonary diseases, in particular for the diagnosis of vascular diseases and the characterization of morphological vascular remodeling in Chronic Obstructive Pulmonary Disease (COPD). In this study, we objectively compare several vessel diameter estimation methods using a physical phantom. Five solid tubes of differing diameters (from 0.898 to 3.980 mm) were embedded in foam, simulating vessels in the lungs. To measure the diameters, we first extracted the vessels using either of two approaches: vessel enhancement using multi-scale Hessian matrix computation, or explicitly segmenting them using intensity threshold. We implemented six methods to quantify the diameter: three estimating diameter as a function of scale used to calculate the Hessian matrix; two calculating equivalent diameter from the crosssection area obtained by thresholding the intensity and vesselness response, respectively; and finally, estimating the diameter of the object using the Full Width Half Maximum (FWHM). We find that the accuracy of frequently used methods estimating vessel diameter from the multi-scale vesselness filter depends on the range and the number of scales used. Moreover, these methods still yield a significant error margin on the challenging estimation of the smallest diameter (on the order or below the size of the CT point spread function). Obviously, the performance of the thresholding-based methods depends on the value of the threshold. Finally, we observe that a simple adaptive thresholding approach can achieve a robust and accurate estimation of the smallest vessels diameter.

  8. Computational and human observer image quality evaluation of low dose, knowledge-based CT iterative reconstruction

    SciTech Connect

    Eck, Brendan L.; Fahmi, Rachid; Miao, Jun; Brown, Kevin M.; Zabic, Stanislav; Raihani, Nilgoun; Wilson, David L.

    2015-10-15

    Purpose: Aims in this study are to (1) develop a computational model observer which reliably tracks the detectability of human observers in low dose computed tomography (CT) images reconstructed with knowledge-based iterative reconstruction (IMR™, Philips Healthcare) and filtered back projection (FBP) across a range of independent variables, (2) use the model to evaluate detectability trends across reconstructions and make predictions of human observer detectability, and (3) perform human observer studies based on model predictions to demonstrate applications of the model in CT imaging. Methods: Detectability (d′) was evaluated in phantom studies across a range of conditions. Images were generated using a numerical CT simulator. Trained observers performed 4-alternative forced choice (4-AFC) experiments across dose (1.3, 2.7, 4.0 mGy), pin size (4, 6, 8 mm), contrast (0.3%, 0.5%, 1.0%), and reconstruction (FBP, IMR), at fixed display window. A five-channel Laguerre–Gauss channelized Hotelling observer (CHO) was developed with internal noise added to the decision variable and/or to channel outputs, creating six different internal noise models. Semianalytic internal noise computation was tested against Monte Carlo and used to accelerate internal noise parameter optimization. Model parameters were estimated from all experiments at once using maximum likelihood on the probability correct, P{sub C}. Akaike information criterion (AIC) was used to compare models of different orders. The best model was selected according to AIC and used to predict detectability in blended FBP-IMR images, analyze trends in IMR detectability improvements, and predict dose savings with IMR. Predicted dose savings were compared against 4-AFC study results using physical CT phantom images. Results: Detection in IMR was greater than FBP in all tested conditions. The CHO with internal noise proportional to channel output standard deviations, Model-k4, showed the best trade-off between fit

  9. Segmentation of the sternum from low-dose chest CT images

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Xie, Yiting; Reeves, Anthony P.

    2015-03-01

    Segmentation of the sternum in medical images is of clinical significance as it frequently serves as a stable reference to image registration and segmentation of other organs in the chest region. In this paper we present a fully automated algorithm to segment the sternum in low-dose chest CT images (LDCT). The proposed algorithm first locates an axial seed slice and then segments the sternum cross section on the seed slice by matching a rectangle model. Furthermore, it tracks and segments the complete sternum in the cranial and caudal direction respectively through sequential axial slices starting from the seed slice. The cross section on each axial slice is segmented using score functions that are designed to have local maxima at the boundaries of the sternum. Finally, the sternal angle is localized. The algorithm is designed to be specifically robust with respect to cartilage calcifications and to accommodate the high noise levels encountered with LDCT images. Segmentation of 351 cases from public datasets was evaluated visually with only 1 failing to produce a usable segmentation. 87.2% of the 351 images have good segmentation and 12.5% have acceptable segmentation. The sternal body segmentation and the localization of the sternal angle and the vertical extents of the sternum were also evaluated quantitatively for 25 good cases and 25 acceptable cases. The overall weighted mean DC of 0.897 and weighted mean distance error of 2.88 mm demonstrate that the algorithm achieves encouraging performance in both segmenting the sternal body and localizing the sternal angle.

  10. Algorithm for x-ray beam hardening and scatter correction in low-dose cone-beam CT: phantom studies

    NASA Astrophysics Data System (ADS)

    Liu, Wenlei; Rong, Junyan; Gao, Peng; Liao, Qimei; Lu, HongBing

    2016-03-01

    X-ray scatter poses a significant limitation to image quality in cone-beam CT (CBCT), as well as beam hardening, resulting in image artifacts, contrast reduction, and lack of CT number accuracy. Meanwhile the x-ray radiation dose is also non-ignorable. Considerable scatter or beam hardening correction methods have been developed, independently, and rarely combined with low-dose CT reconstruction. In this paper, we combine scatter suppression with beam hardening correction for sparse-view CT reconstruction to improve CT image quality and reduce CT radiation. Firstly, scatter was measured, estimated, and removed using measurement-based methods, assuming that signal in the lead blocker shadow is only attributable to x-ray scatter. Secondly, beam hardening was modeled by estimating an equivalent attenuation coefficient at the effective energy, which was integrated into the forward projector of the algebraic reconstruction technique (ART). Finally, the compressed sensing (CS) iterative reconstruction is carried out for sparse-view CT reconstruction to reduce the CT radiation. Preliminary Monte Carlo simulated experiments indicate that with only about 25% of conventional dose, our method reduces the magnitude of cupping artifact by a factor of 6.1, increases the contrast by a factor of 1.4 and the CNR by a factor of 15. The proposed method could provide good reconstructed image from a few view projections, with effective suppression of artifacts caused by scatter and beam hardening, as well as reducing the radiation dose. With this proposed framework and modeling, it may provide a new way for low-dose CT imaging.

  11. SU-E-P-49: Evaluation of Image Quality and Radiation Dose of Various Unenhanced Head CT Protocols

    SciTech Connect

    Chen, L; Khan, M; Alapati, K; Hsieh, M; Barry, K

    2015-06-15

    Purpose: To evaluate the diagnostic value of various unenhanced head CT protocols and predicate acceptable radiation dose level for head CT exam. Methods: Our retrospective analysis included 3 groups, 20 patients per group, who underwent clinical routine unenhanced adult head CT examination. All exams were performed axially with 120 kVp. Three protocols, 380 mAs without iterative reconstruction and automAs, 340 mAs with iterative reconstruction without automAs, 340 mAs with iterative reconstruction and automAs, were applied on each group patients respectively. The images were reconstructed with H30, J30 for brain window and H60, J70 for bone window. Images acquired with three protocols were randomized and blindly reviewed by three radiologists. A 5 point scale was used to rate each exam The percentage of exam score above 3 and average scores of each protocol were calculated for each reviewer and tissue types. Results: For protocols without automAs, the average scores of bone window with iterative reconstruction were higher than those without iterative reconstruction for each reviewer although the radiation dose was 10 percentage lower. 100 percentage exams were scored 3 or higher and the average scores were above 4 for both brain and bone reconstructions. The CTDIvols are 64.4 and 57.8 mGy of 380 and 340 mAs, respectively. With automAs, the radiation dose varied with head size, resulting in 47.5 mGy average CTDIvol between 39.5 and 56.5 mGy. 93 and 98 percentage exams were scored great than 3 for brain and bone windows, respectively. The diagnostic confidence level and image quality of exams with AutomAs were less than those without AutomAs for each reviewer. Conclusion: According to these results, the mAs was reduced to 300 with automAs OFF for head CT exam. The radiation dose was 20 percentage lower than the original protocol and the CTDIvol was reduced to 51.2 mGy.

  12. Automatic lobar segmentation for diseased lungs using an anatomy-based priority knowledge in low-dose CT images

    NASA Astrophysics Data System (ADS)

    Park, Sang Joon; Kim, Jung Im; Goo, Jin Mo; Lee, Doohee

    2014-03-01

    Lung lobar segmentation in CT images is a challenging tasks because of the limitations in image quality inherent to CT image acquisition, especially low-dose CT for clinical routine environment. Besides, complex anatomy and abnormal lesions in the lung parenchyma makes segmentation difficult because contrast in CT images are determined by the differential absorption of X-rays by neighboring structures, such as tissue, vessel or several pathological conditions. Thus, we attempted to develop a robust segmentation technique for normal and diseased lung parenchyma. The images were obtained with low-dose chest CT using soft reconstruction kernel (Sensation 16, Siemens, Germany). Our PC-based in-house software segmented bronchial trees and lungs with intensity adaptive region-growing technique. Then the horizontal and oblique fissures were detected by using eigenvalues-ratio of the Hessian matrix in the lung regions which were excluded from airways and vessels. To enhance and recover the faithful 3-D fissure plane, our proposed fissure enhancing scheme were applied to the images. After finishing above steps, for careful smoothening of fissure planes, 3-D rolling-ball algorithm in xyz planes were performed. Results show that success rate of our proposed scheme was achieved up to 89.5% in the diseased lung parenchyma.

  13. A computer simulation method for low-dose CT images by use of real high-dose images: a phantom study.

    PubMed

    Takenaga, Tomomi; Katsuragawa, Shigehiko; Goto, Makoto; Hatemura, Masahiro; Uchiyama, Yoshikazu; Shiraishi, Junji

    2016-01-01

    Practical simulations of low-dose CT images have a possibility of being helpful means for optimization of the CT exposure dose. Because current methods reported by several researchers are limited to specific vendor platforms and generally rely on raw sinogram data that are difficult to access, we have developed a new computerized scheme for producing simulated low-dose CT images from real high-dose images without use of raw sinogram data or of a particular phantom. Our computerized scheme for low-dose CT simulation was based on the addition of a simulated noise image to a real high-dose CT image reconstructed by the filtered back-projection algorithm. First, a sinogram was generated from the forward projection of a high-dose CT image. Then, an additional noise sinogram resulting from use of a reduced exposure dose was estimated from a predetermined noise model. Finally, a noise CT image was reconstructed with a predetermined filter and was added to the real high-dose CT image to create a simulated low-dose CT image. The noise power spectrum and modulation transfer function of the simulated low-dose images were very close to those of the real low-dose images. In order to confirm the feasibility of our method, we applied this method to clinical cases which were examined with the high dose initially and then followed with a low-dose CT. In conclusion, our proposed method could simulate the low-dose CT images from their real high-dose images with sufficient accuracy and could be used for determining the optimal dose setting for various clinical CT examinations. PMID:26290269

  14. Towards robust deconvolution of low-dose perfusion CT: sparse perfusion deconvolution using online dictionary learning.

    PubMed

    Fang, Ruogu; Chen, Tsuhan; Sanelli, Pina C

    2013-05-01

    Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular diseases, particularly in acute stroke and vasospasm. However, the post-processed parametric maps of blood flow tend to be noisy, especially in low-dose CTP, due to the noisy contrast enhancement profile and the oscillatory nature of the results generated by the current computational methods. In this paper, we propose a robust sparse perfusion deconvolution method (SPD) to estimate cerebral blood flow in CTP performed at low radiation dose. We first build a dictionary from high-dose perfusion maps using online dictionary learning and then perform deconvolution-based hemodynamic parameters estimation on the low-dose CTP data. Our method is validated on clinical data of patients with normal and pathological CBF maps. The results show that we achieve superior performance than existing methods, and potentially improve the differentiation between normal and ischemic tissue in the brain. PMID:23542422

  15. Towards robust deconvolution of low-dose perfusion CT: Sparse perfusion deconvolution using online dictionary learning

    PubMed Central

    Fang, Ruogu; Chen, Tsuhan; Sanelli, Pina C.

    2014-01-01

    Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular diseases, particularly in acute stroke and vasospasm. However, the post-processed parametric maps of blood flow tend to be noisy, especially in low-dose CTP, due to the noisy contrast enhancement profile and the oscillatory nature of the results generated by the current computational methods. In this paper, we propose a robust sparse perfusion deconvolution method (SPD) to estimate cerebral blood flow in CTP performed at low radiation dose. We first build a dictionary from high-dose perfusion maps using online dictionary learning and then perform deconvolution-based hemodynamic parameters estimation on the low-dose CTP data. Our method is validated on clinical data of patients with normal and pathological CBF maps. The results show that we achieve superior performance than existing methods, and potentially improve the differentiation between normal and ischemic tissue in the brain. PMID:23542422

  16. A clinical evaluation of total variation-Stokes image reconstruction strategy for low-dose CT imaging of the chest

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Zhang, Hao; Moore, William; Bhattacharji, Priya; Liang, Zhengrong

    2015-03-01

    One hundred "normal-dose" computed tomography (CT) studies of the chest (i.e., 1,160 projection views, 120kVp, 100mAs) data sets were acquired from the patients who were scheduled for lung biopsy at Stony Brook University Hospital under informed consent approved by our Institutional Review Board. To mimic low-dose CT imaging scenario (i.e., sparse-view scan), sparse projection views were evenly extracted from the total 1,160 projections of each patient and the total radiation dose was reduced according to how many sparse views were selected. A standard filtered backprojection (FBP) algorithm was applied to the 1160 projections to produce reference images for comparison purpose. In the low-dose scenario, both the FBP and total variation-stokes (TVS) algorithms were applied to reconstruct the corresponding low-dose images. The reconstructed images were evaluated by an experienced thoracic radiologist against the reference images. Both the low-dose reconstructions and the reference images were displayed on a 4- megapixel monitor in soft tissue and lung windows. The images were graded by a five-point scale from 0 to 4 (0, nondiagnostic; 1, severe artifact with low confidence; 2, moderate artifact or moderate diagnostic confidences; 3, mild artifact or high confidence; 4, well depicted without artifacts). Quantitative evaluation measurements such as standard deviations for different tissue types and universal quality index were also studied and reported for the results. The evaluation concluded that the TVS can reduce the view number from 1,160 to 580 with slightly lower scores as the reference, resulting in a dose reduction to close 50%.

  17. SU-E-I-25: Determining Tube Current, Tube Voltage and Pitch Suitable for Low- Dose Lung Screening CT

    SciTech Connect

    Williams, K; Matthews, K

    2014-06-01

    Purpose: The quality of a computed tomography (CT) image and the dose delivered during its acquisition depend upon the acquisition parameters used. Tube current, tube voltage, and pitch are acquisition parameters that potentially affect image quality and dose. This study investigated physicians' abilities to characterize small, solid nodules in low-dose CT images for combinations of current, voltage and pitch, for three CT scanner models. Methods: Lung CT images was acquired of a Data Spectrum anthropomorphic torso phantom with various combinations of pitch, tube current, and tube voltage; this phantom was used because acrylic beads of various sizes could be placed within the lung compartments to simulate nodules. The phantom was imaged on two 16-slice scanners and a 64-slice scanner. The acquisition parameters spanned a range of estimated CTDI levels; the CTDI estimates from the acquisition software were verified by measurement. Several experienced radiologists viewed the phantom lung CT images and noted nodule location, size and shape, as well as the acceptability of overall image quality. Results: Image quality for assessment of nodules was deemed unsatisfactory for all scanners at 80 kV (any tube current) and at 35 mA (any tube voltage). Tube current of 50 mA or more at 120 kV resulted in similar assessments from all three scanners. Physician-measured sphere diameters were closer to actual diameters for larger spheres, higher tube current, and higher kV. Pitch influenced size measurements less for larger spheres than for smaller spheres. CTDI was typically overestimated by the scanner software compared to measurement. Conclusion: Based on this survey of acquisition parameters, a low-dose CT protocol of 120 kV, 50 mA, and pitch of 1.4 is recommended to balance patient dose and acceptable image quality. For three models of scanners, this protocol resulted in estimated CTDIs from 2.9–3.6 mGy.

  18. Implementation of an effective KL domain penalized weighted least-squares sinogram restoration for low-dose CT colonography

    NASA Astrophysics Data System (ADS)

    Fan, Yi; Wang, Jing; Lu, Hongbing; Liang, Zhengrong

    2009-02-01

    Currently available spiral/helical computed tomography (HCT) technologies have demonstrated the potential for CTbased virtual colonoscopy or CT-colonography (CTC). However, a major limitation for this clinical application is associated with the risk of high radiation exposure, especially for its use for screening purpose at a large population. In this work, we presented an improved Karhunen-Loeve (KL) domain penalized weighted least-squares (PWLS) strategy which considers the data correlation among the nearby angular views and nearby axial slices simultaneously so that a fully three-dimensional (3D) restoration problem can be reduced to a 1D operation and therefore an analytical calculation is feasible for highest computing efficiency. The KL-PWLS strategy was implemented and tested on computer simulated sinograms which mimic low-dose CT scans at different noise levels characterized by 50, 40, 30, 20 and 10 mAs respectively. The reconstructed images by the presented strategy demonstrated the potential of ultra low-dose CT at as low as 10 mAs for VC application. Further evaluation by receiver operating characteristic study is needed and is under progress.

  19. State of the art low-dose CT angiography of the body.

    PubMed

    Alkadhi, Hatem; Schindera, Sebastian T

    2011-10-01

    This review summarizes current evidence based on pertinent literature on low-dose computed tomography angiography (CTA) of the body. Various strategies for optimizing CTA protocols with the aim to lower the radiation dose while maintaining the diagnostic accuracy of the examination are summarized. To date, various publications have demonstrated that CTA of the body can be performed at a low radiation dose while providing high quality information. Nevertheless, a number of questions still need to be answered, including the optimal combination of tube voltage and tube current settings, as well as the appropriate protocol parameters in relation to the body physiognomy and the specific body region imaged. PMID:21330084

  20. Ultra-low dose comprehensive cardiac CT imaging in a patient with acute myocarditis.

    PubMed

    Tröbs, Monique; Brand, Michael; Achenbach, Stephan; Marwan, Mohamed

    2014-01-01

    The ability of contrast-enhanced CT to detect "late enhancement" in a fashion similar to magnetic resonance imaging has been previously reported. We report a case of acute myocarditis with coronary CT angiography as well as "late enhancement" imaging with ultra-low effective radiation dose. PMID:25439792

  1. Investigation of ultra low-dose scans in the context of quantum-counting clinical CT

    NASA Astrophysics Data System (ADS)

    Weidinger, T.; Buzug, T. M.; Flohr, T.; Fung, G. S. K.; Kappler, S.; Stierstorfer, K.; Tsui, B. M. W.

    2012-03-01

    In clinical computed tomography (CT), images from patient examinations taken with conventional scanners exhibit noise characteristics governed by electronics noise, when scanning strongly attenuating obese patients or with an ultra-low X-ray dose. Unlike CT systems based on energy integrating detectors, a system with a quantum counting detector does not suffer from this drawback. Instead, the noise from the electronics mainly affects the spectral resolution of these detectors. Therefore, it does not contribute to the image noise in spectrally non-resolved CT images. This promises improved image quality due to image noise reduction in scans obtained from clinical CT examinations with lowest X-ray tube currents or obese patients. To quantify the benefits of quantum counting detectors in clinical CT we have carried out an extensive simulation study of the complete scanning and reconstruction process for both kinds of detectors. The simulation chain encompasses modeling of the X-ray source, beam attenuation in the patient, and calculation of the detector response. Moreover, in each case the subsequent image preprocessing and reconstruction is modeled as well. The simulation-based, theoretical evaluation is validated by experiments with a novel prototype quantum counting system and a Siemens Definition Flash scanner with a conventional energy integrating CT detector. We demonstrate and quantify the improvement from image noise reduction achievable with quantum counting techniques in CT examinations with ultra-low X-ray dose and strong attenuation.

  2. Low-Dose PET/CT and Full-Dose Contrast-Enhanced CT at the Initial Staging of Localized Diffuse Large B-Cell Lymphomas

    PubMed Central

    Sabaté-Llobera, Aida; Cortés-Romera, Montserrat; Mercadal, Santiago; Hernández-Gañán, Javier; Pomares, Helena; González-Barca, Eva; Gámez-Cenzano, Cristina

    2016-01-01

    Computed tomography (CT) has been used as the reference imaging technique for the initial staging of diffuse large B-cell lymphoma until recent days, when the introduction of positron emission tomography (PET)/CT imaging as a hybrid technique has become of routine use. However, the performance of both examinations is still common. The aim of this work was to compare the findings between low-dose 2-deoxy-2-(18F)fluoro-d-glucose (18F-FDG) PET/CT and full-dose contrast-enhanced CT (ceCT) in 28 patients with localized diffuse large B-cell lymphoma according to PET/CT findings, in order to avoid the performance of ceCT. For each technique, a comparison in the number of nodal and extranodal involved regions was performed. PET/CT showed more lesions than ceCT in both nodal (41 vs. 36) and extranodal localizations (16 vs. 15). Disease staging according to both techniques was concordant in 22 patients (79%) and discordant in 6 patients (21%), changing treatment management in 3 patients (11%). PET/CT determined a better staging and therapeutic approach, making the performance of an additional ceCT unnecessary. PMID:27559300

  3. Initial evaluation of virtual un-enhanced imaging derived from fast kVp-switching dual energy contrast enhanced CT for the abdomen

    NASA Astrophysics Data System (ADS)

    Joshi, M.; Mendonca, P.; Okerlund, D.; Lamb, P.; Kulkarni, N.; Pinho, D.; Sahani, D.; Bhotika, R.

    2011-03-01

    The feasibility and utility of creating virtual un-enhanced images from contrast enhanced data acquired using a fast switching dual energy CT acquisition, is explored. Utilizing projection based material decomposition data, monochromatic images are generated and a Multi-material decomposition technique is applied. Quantitative and qualitative evaluation is performed to assess the equivalence of Virtual Un-Enhanced (VUE) and True Un-enhanced (TUE) for multiple tissue types and different organs in the abdomen. Ten patient cases were analyzed where a TUE and a subsequent Contrast Enhanced (CE) acquisition were obtained using fast kVp-switching dual energy CT utilizing Gemstone Spectral Imaging. Quantitative measurements were made by placing multiple Regions of Interest on the different tissues and organs in both the TUE and the VUE images. The absolute Hounsfield Unit (HU) differences in the mean values between TUE & VUE were calculated as well as the differences of the standard deviations. Qualitative analysis was done by two radiologists for overall image quality, presence of residual contrast, appearance of pathology, appearance and contrast of normal tissues and organs in comparison to the TUE. There is a very strong correlation between the TUE and VUE images.

  4. Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study.

    PubMed

    Brodén, Cyrus; Olivecrona, Henrik; Maguire, Gerald Q; Noz, Marilyn E; Zeleznik, Michael P; Sköldenberg, Olof

    2016-01-01

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty. Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated. Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv. Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting. PMID:27478832

  5. Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study

    PubMed Central

    Olivecrona, Henrik; Maguire, Gerald Q.; Noz, Marilyn E.; Zeleznik, Michael P.

    2016-01-01

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty. Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated. Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv. Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting. PMID:27478832

  6. Adaptive nonlocal means-based regularization for statistical image reconstruction of low-dose X-ray CT

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Ma, Jianhua; Wang, Jing; Liu, Yan; Han, Hao; Li, Lihong; Moore, William; Liang, Zhengrong

    2015-03-01

    To reduce radiation dose in X-ray computed tomography (CT) imaging, one of the common strategies is to lower the milliampere-second (mAs) setting during projection data acquisition. However, this strategy would inevitably increase the projection data noise, and the resulting image by the filtered back-projection (FBP) method may suffer from excessive noise and streak artifacts. The edge-preserving nonlocal means (NLM) filtering can help to reduce the noise-induced artifacts in the FBP reconstructed image, but it sometimes cannot completely eliminate them, especially under very low-dose circumstance when the image is severely degraded. To deal with this situation, we proposed a statistical image reconstruction scheme using a NLM-based regularization, which can suppress the noise and streak artifacts more effectively. However, we noticed that using uniform filtering parameter in the NLM-based regularization was rarely optimal for the entire image. Therefore, in this study, we further developed a novel approach for designing adaptive filtering parameters by considering local characteristics of the image, and the resulting regularization is referred to as adaptive NLM-based regularization. Experimental results with physical phantom and clinical patient data validated the superiority of using the proposed adaptive NLM-regularized statistical image reconstruction method for low-dose X-ray CT, in terms of noise/streak artifacts suppression and edge/detail/contrast/texture preservation.

  7. Impact of low-dose CT scan in dual timepoint investigations: a phantom study

    NASA Astrophysics Data System (ADS)

    Micheelsen, M. A.; Jensen, M.

    2011-09-01

    Dual timepoint FDG takeup investigations have a potential for separating malignant lymph nodes from non-malignant in certain cases of suspected lung cancer. One hour seems to be the optimal time interval between the two scans (50-120 min). Many of the new PET scanners benefit from image fusion with a CT image and also use the CT for attenuation correction. In any practical hospital setting, 1 hour is too long to occupy the scanner bed and a second CT procedure thus becomes necessary. This study tries to validate to what extent the dose/quality of the second CT scan can be lowered, without compromising attenuation correction, lesion detection and quantification. Using a standard NEMA phantom with the GE Discovery PET/CT scanner, taken in and out between scan sessions, we have tried to find the minimal CT dose necessary for the second scan while still reaching tissue activity quantification within predetermined error limits. For a hot sphere to background activity concentration ratio of 1:5, the average uptake (normalised by the time corrected input activity concentration) in a sphere of 6 cm3 was found to be 0.90 ± 0.08 for the standard scan, yielding a dose of 5.5 mGy, and 0.90 ± 0.14 for a scan with lowest possible mAs product and lowest possible kV, yielding a dose of 0.65 mGy. With an insignificant increase in the uncertainty in the uptake measurement, we can get an order of magnitude reduction for the CT dose.

  8. Comparison of biophysical factors influencing on emphysema quantification with low-dose CT

    NASA Astrophysics Data System (ADS)

    Heo, Chang Yong; Kim, Jong Hyo

    2014-03-01

    Emphysema Index(EI) measurements in MDCT is known to be influenced by various biophysical factors such as total lung volume, and body size. We investigated the association of the four biophysical factors with emphysema index in low-dose MDCT. In particular, we attempted to identify a potentially stronger biophysical factor than total lung volume. A total of 400 low-dose MDCT volumes taken at 120kVp, 40mAs, 1mm thickness, and B30f reconstruction kernel were used. The lungs, airways, and pulmonary vessels were automatically segmented, and two Emphysema Indices, relative area below -950HU(RA950) and 15th percentile(Perc15), were extracted from the segmented lungs. The biophysical factors such as total lung volume(TLV), mode of lung attenuation(ModLA), effective body diameter(EBD), and the water equivalent body diameter(WBD) were estimated from the segmented lung and body area. The association of biophysical factors with emphysema indices were evaluated by correlation coefficients. The mean emphysema indices were 8.3±5.5(%) in RA950, and -930±18(HU) in Perc15. The estimates of biophysical factors were 4.7±1.0(L) in TLV, -901±21(HU) in ModLA, 26.9±2.2(cm) in EBD, and 25.9±2.6(cm) in WBD. The correlation coefficients of biophysical factors with RA950 were 0.73 in TLV, 0.94 in ModLA, 0.31 in EBD, and 0.18 WBD, the ones with Perc15 were 0.74 in TLV, 0.98 in ModLA, 0.29 in EBD, and 0.15 WBD. Study results revealed that two biophysical factors, TLV and ModLA, mostly affects the emphysema indices. In particular, the ModLA exhibited strongest correlation of 0.98 with Perc15, which indicating the ModLA is the most significant confounding biophysical factor in emphysema indices measurement.

  9. Low-Dose Megavoltage Cone-Beam CT imaging using Thick, Segmented Scintillators

    PubMed Central

    El-Mohri, Youcef; Antonuk, Larry E.; Zhao, Qihua; Choroszucha, Richard B.; Jiang, Hao; Liu, Langechuan

    2011-01-01

    Megavoltage, cone-beam computed tomography (MV CBCT) employing an electronic portal imaging device (EPID) is a highly promising technique for providing soft-tissue visualization in image-guided radiotherapy. However, current EPIDs based on active matrix flat-panel imagers (AMFPIs), which are regarded as the gold standard for portal imaging and referred to as conventional MV AMFPIs, require high radiation doses to achieve this goal due to poor x-ray detection efficiency (~2% at 6 MV). To overcome this limitation, the incorporation of thick, segmented, crystalline scintillators, as a replacement for the phosphor screens used in these AMFPIs, has been shown to significantly improve the DQE performance, leading to improved image quality for projection imaging at low dose. Toward the realization of practical AMFPIs capable of low dose, soft-tissue visualization using MV CBCT imaging, two prototype AMFPIs incorporating segmented scintillators with ~11 mm thick CsI:Tl and BGO crystals were evaluated. Each scintillator consists of 120 × 60 crystalline elements separated by reflective septal walls, with an element-to-element pitch of 1.016 mm. The prototypes were evaluated using a bench-top CBCT system, allowing the acquisition of 180 projection, 360° tomographic scans with a 6 MV radiotherapy photon beam. Reconstructed images of a spatial resolution phantom, as well as of a water-equivalent phantom, embedded with tissue equivalent objects having electron densities (relative to water) varying from ~0.28 to ~1.70, were obtained down to one beam pulse per projection image, corresponding to a scan dose of ~4 cGy – a dose similar to that required for a single portal image obtained from a conventional MV AMFPI. By virtue of their significantly improved DQE, the prototypes provided low contrast visualization, allowing clear delineation of an object with an electron density difference of ~2.76%. Results of contrast, noise and contrast-to-noise ratio are presented as a function

  10. Low-dose megavoltage cone-beam CT imaging using thick, segmented scintillators

    NASA Astrophysics Data System (ADS)

    El-Mohri, Youcef; Antonuk, Larry E.; Zhao, Qihua; Choroszucha, Richard B.; Jiang, Hao; Liu, Langechuan

    2011-03-01

    Megavoltage, cone-beam computed tomography (MV CBCT) employing an electronic portal imaging device (EPID) is a highly promising technique for providing soft-tissue visualization in image-guided radiotherapy. However, current EPIDs based on active matrix flat-panel imagers (AMFPIs), which are regarded as the gold standard for portal imaging and referred to as conventional MV AMFPIs, require high radiation doses to achieve this goal due to poor x-ray detection efficiency (~2% at 6 MV). To overcome this limitation, the incorporation of thick, segmented, crystalline scintillators, as a replacement for the phosphor screens used in these AMFPIs, has been shown to significantly improve the detective quantum efficiency (DQE) performance, leading to improved image quality for projection imaging at low dose. Toward the realization of practical AMFPIs capable of low dose, soft-tissue visualization using MV CBCT imaging, two prototype AMFPIs incorporating segmented scintillators with ~11 mm thick CsI:Tl and Bi4Ge3O12 (BGO) crystals were evaluated. Each scintillator consists of 120 × 60 crystalline elements separated by reflective septal walls, with an element-to-element pitch of 1.016 mm. The prototypes were evaluated using a bench-top CBCT system, allowing the acquisition of 180 projection, 360° tomographic scans with a 6 MV radiotherapy photon beam. Reconstructed images of a spatial resolution phantom, as well as of a water-equivalent phantom, embedded with tissue equivalent objects having electron densities (relative to water) varying from ~0.28 to ~1.70, were obtained down to one beam pulse per projection image, corresponding to a scan dose of ~4 cGy--a dose similar to that required for a single portal image obtained from a conventional MV AMFPI. By virtue of their significantly improved DQE, the prototypes provided low contrast visualization, allowing clear delineation of an object with an electron density difference of ~2.76%. Results of contrast, noise and contrast

  11. Task-based image quality evaluation of iterative reconstruction methods for low dose CT using computer simulations

    NASA Astrophysics Data System (ADS)

    Xu, Jingyan; Fuld, Matthew K.; Fung, George S. K.; Tsui, Benjamin M. W.

    2015-04-01

    Iterative reconstruction (IR) methods for x-ray CT is a promising approach to improve image quality or reduce radiation dose to patients. The goal of this work was to use task based image quality measures and the channelized Hotelling observer (CHO) to evaluate both analytic and IR methods for clinical x-ray CT applications. We performed realistic computer simulations at five radiation dose levels, from a clinical reference low dose D0 to 25% D0. A fixed size and contrast lesion was inserted at different locations into the liver of the XCAT phantom to simulate a weak signal. The simulated data were reconstructed on a commercial CT scanner (SOMATOM Definition Flash; Siemens, Forchheim, Germany) using the vendor-provided analytic (WFBP) and IR (SAFIRE) methods. The reconstructed images were analyzed by CHOs with both rotationally symmetric (RS) and rotationally oriented (RO) channels, and with different numbers of lesion locations (5, 10, and 20) in a signal known exactly (SKE), background known exactly but variable (BKEV) detection task. The area under the receiver operating characteristic curve (AUC) was used as a summary measure to compare the IR and analytic methods; the AUC was also used as the equal performance criterion to derive the potential dose reduction factor of IR. In general, there was a good agreement in the relative AUC values of different reconstruction methods using CHOs with RS and RO channels, although the CHO with RO channels achieved higher AUCs than RS channels. The improvement of IR over analytic methods depends on the dose level. The reference dose level D0 was based on a clinical low dose protocol, lower than the standard dose due to the use of IR methods. At 75% D0, the performance improvement was statistically significant (p < 0.05). The potential dose reduction factor also depended on the detection task. For the SKE/BKEV task involving 10 lesion locations, a dose reduction of at least 25% from D0 was achieved.

  12. The assessment of the role of baseline low-dose CT scan in patients at high risk of lung cancer

    PubMed Central

    Kołaczyk, Katarzyna; Walecka, Anna; Grodzki, Tomasz; Alchimowicz, Jacek; Smereczyński, Andrzej; Kiedrowicz, Radosław

    2014-01-01

    Summary Background Despite the progress in contemporary medicine comprising diagnostic and therapeutic methods, lung cancer is still one of the biggest health concerns in many countries of the world. The main purpose of the study was to evaluate the detection rate of pulmonary nodules and lung cancer in the initial, helical low-dose CT of the chest as well as the analysis of the relationship between the size and the histopathological character of the detected nodules. Material/Methods We retrospectively evaluated 1999 initial, consecutive results of the CT examinations performed within the framework of early lung cancer detection program initiated in Szczecin. The project enrolled persons of both sexes, aged 55–65 years, with at least 20 pack-years of cigarette smoking or current smokers. The analysis included assessment of the number of positive results and the evaluation of the detected nodules in relationship to their size. All of the nodules were classified into I of VI groups and subsequently compared with histopathological type of the neoplastic and nonneoplastic pulmonary lesions. Results Pulmonary nodules were detected in 921 (46%) subjects. What is more, malignant lesions as well as lung cancer were significantly, more frequently discovered in the group of asymptomatic nodules of the largest dimension exceeding 15 mm. Conclusions The initial, low-dose helical CT of the lungs performed in high risk individuals enables detection of appreciable number of indeterminate pulmonary nodules. In most of the asymptomatic patients with histopathologically proven pulmonary nodules greater than 15 mm, the mentioned lesions are malignant, what warrants further, intensified diagnostics. PMID:25057333

  13. Automatic LV volume measurement in low dose multi-phase CT by shape tracking

    NASA Astrophysics Data System (ADS)

    von Berg, Jens; Begemann, Philipp; Stahmer, Felix; Adam, Gerhard; Lorenz, Cristian

    2006-03-01

    Functional assessment of cardiac ventricular function requires time consuming manual interaction. Some automated methods have been presented that predominantly used cardiac magnet resonance images. Here, an automatic shape tracking approach is followed to estimate left ventricular blood volume from multi-slice computed tomography image series acquired with retrospective ECG-gating. A deformable surface model method was chosen that utilized both shape and local appearance priors to determine the endocardial surface and to follow its motion through the cardiac cycle. Functional parameters like the ejection fraction could be calculated from the estimated shape deformation. A clinical validation was performed in a porcine model with 60 examinations on eight subjects. The functional parameters showed a good correlation with those determined by clinical experts using a commercially available semi-automatic short axes delineation tool. The correlation coefficient for the ejection fraction (EF) was 0.89. One quarter of these acquisitions were done with a low dose protocol. All of these degraded images could be processed well. Their correlation slightly decreases when compared to the normal dose cases (EF: 0.87 versus 0.88).

  14. Projection domain denoising method based on dictionary learning for low-dose CT image reconstruction.

    PubMed

    Zhang, Haiyan; Zhang, Liyi; Sun, Yunshan; Zhang, Jingyu

    2015-01-01

    Reducing X-ray tube current is one of the widely used methods for decreasing the radiation dose. Unfortunately, the signal-to-noise ratio (SNR) of the projection data degrades simultaneously. To improve the quality of reconstructed images, a dictionary learning based penalized weighted least-squares (PWLS) approach is proposed for sinogram denoising. The weighted least-squares considers the statistical characteristic of noise and the penalty models the sparsity of sinogram based on dictionary learning. Then reconstruct CT image using filtered back projection (FBP) algorithm from the denoised sinogram. The proposed method is particularly suitable for the projection data with low SNR. Experimental results show that the proposed method can get high-quality CT images when the signal to noise ratio of projection data declines sharply. PMID:26409424

  15. Low-Dose High-Pitch CT Angiography of the Supraaortic Arteries Using Sinogram-Affirmed Iterative Reconstruction

    PubMed Central

    Beitzke, Dietrich; Nolz, Richard; Unterhumer, Sylvia; Plank, Christina; Weber, Michael; Schernthaner, Rüdiger; Schöpf, Veronika; Wolf, Florian; Loewe, Christian

    2014-01-01

    Objective To prospectively evaluate image quality and radiation dose using a low-dose computed tomography angiography protocol and iterative image reconstruction for high-pitch dual-source CT-angiography (DSCTA) of the supraaortic arteries. Material and Methods DSCTA was performed in 42 patients, using either 120 kVp tube voltage, 120 mAS tube current, 2.4 pitch and filtered back projection, or 100 kVp tube voltage, 100 mAs tube current, 3.2 pitch, and sinogram affirmed iterative reconstruction. Measurements of vessel attenuation, of the contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) were performed to objectively evaluate image quality. Two readers evaluated subjective image quality and image noise, using a four-point scale. Effective dose was used to compare the differences in radiation dose. Results Low-dose protocol application showed significantly higher vessel opacification (p = 0.013), and non-significantly higher CNR and SNR values. There was no difference in the subjective image quality and image noise reading between the protocols. Effective dose was significantly lower using the low-dose protocol (1.29±0.21 mSv vs. 2.92±0.72 mSv; p<0.001). Conclusion The combined use of reduced tube voltage, reduced tube current, and iterative reconstruction reduces radiation dose by 55.4% in high-pitch DSCTA of the supraaortic arteries without impairment of image quality. PMID:24919195

  16. Longitudinal follow-up study of smoking-induced emphysema progression in low-dose CT screening of lung cancer

    NASA Astrophysics Data System (ADS)

    Suzuki, H.; Matsuhiro, M.; Kawata, Y.; Niki, N.; Nakano, Y.; Ohmatsu, H.; Kusumoto, M.; Tsuchida, T.; Eguchi, K.; Kaneko, Masahiro; Moriyama, N.

    2014-03-01

    Chronic obstructive pulmonary disease is a major public health problem that is predicted to be third leading cause of death in 2030. Although spirometry is traditionally used to quantify emphysema progression, it is difficult to detect the loss of pulmonary function by emphysema in early stage, and to assess the susceptibility to smoking. This study presents quantification method of smoking-induced emphysema progression based on annual changes of low attenuation volume (LAV) by each lung lobe acquired from low-dose CT images in lung cancer screening. The method consists of three steps. First, lung lobes are segmented using extracted interlobar fissures by enhancement filter based on fourdimensional curvature. Second, LAV of each lung lobe is segmented. Finally, smoking-induced emphysema progression is assessed by statistical analysis of the annual changes represented by linear regression of LAV percentage in each lung lobe. This method was applied to 140 participants in lung cancer CT screening for six years. The results showed that LAV progressions of nonsmokers, past smokers, and current smokers are different in terms of pack-year and smoking cessation duration. This study demonstrates effectiveness in diagnosis and prognosis of early emphysema in lung cancer CT screening.

  17. Low dose CT image restoration using a database of image patches

    NASA Astrophysics Data System (ADS)

    Ha, Sungsoo; Mueller, Klaus

    2015-01-01

    Reducing the radiation dose in CT imaging has become an active research topic and many solutions have been proposed to remove the significant noise and streak artifacts in the reconstructed images. Most of these methods operate within the domain of the image that is subject to restoration. This, however, poses limitations on the extent of filtering possible. We advocate to take into consideration the vast body of external knowledge that exists in the domain of already acquired medical CT images, since after all, this is what radiologists do when they examine these low quality images. We can incorporate this knowledge by creating a database of prior scans, either of the same patient or a diverse corpus of different patients, to assist in the restoration process. Our paper follows up on our previous work that used a database of images. Using images, however, is challenging since it requires tedious and error prone registration and alignment. Our new method eliminates these problems by storing a diverse set of small image patches in conjunction with a localized similarity matching scheme. We also empirically show that it is sufficient to store these patches without anatomical tags since their statistics are sufficiently strong to yield good similarity matches from the database and as a direct effect, produce image restorations of high quality. A final experiment demonstrates that our global database approach can recover image features that are difficult to preserve with conventional denoising approaches.

  18. Is hepatotropic contrast enhanced MR a more effective method in differential diagnosis of hemangioma than multi-phase CT and unenhanced MR?

    PubMed Central

    2011-01-01

    Background Cavernous hemangiomas are the most frequent neoplasms of the liver and in routine clinical practice they often need to be differentiated from malignant tumors and other benign focal lesions. The purpose of this study is to evaluate whether diagnostic accuracy of magnetic resonance imaging (MRI) of hepatic hemangiomas, showing atypical pattern on US, improves with the use of Gd-BOPTA in comparison with contrast-enhanced multi-phase computed tomography (CT). Methods 178 consecutive patients with ambiguous hepatic masses showing atypical hyperechoic pattern on grey-scale US, underwent unenhanced and contrast-enhanced multi-phase multi-detector CT and MR (1.5T) with the use of liver-specific contrast medium gadobenate dimeglumine (Gd-BOPTA). After intravenous contrast administration arterial (HAP), venous-portal (PVP), equilibrium phases (EP) both in CT and MR and additionally hepatobiliary phase (HBP) in MR were obtained. 398 lesions have been detected including 99 hemangiomas and 299 other lesions. Results In non-enhanced MDCT examination detection of hemangiomas was characterized by sensitivity of 76%, specificity of 90%, PPV of 71%, NPV of 92% and accuracy of 86%. Non-enhanced MR examination showed sensitivity of 98%, specificity of 99%, PPV of 99%, NPV of 99% and accuracy of 99%. After intravenous administration of contrast medium in MR the mentioned above parameters did not increase significantly. Conclusion Gd-BOPTA-enhanced MR in comparison with unenhanced MRI does not improve diagnostic accuracy in discriminating hemangiomas that show non-specific appearance in ultrasound examination. Unenhanced MR as a method of choice should directly follow US in course of diagnostic algorithm in differentiation of hemangiomas from other liver tumors. PMID:21504593

  19. Extracting information from previous full-dose CT scan for knowledge-based Bayesian reconstruction of current low-dose CT images

    PubMed Central

    Zhang, Hao; Han, Hao; Liang, Zhengrong; Hu, Yifan; Liu, Yan; Moore, William; Ma, Jianhua; Lu, Hongbing

    2015-01-01

    Markov random field (MRF) model has been widely employed in edge-preserving regional noise smoothing penalty to reconstruct piece-wise smooth images in the presence of noise, such as in low-dose computed tomography (LdCT). While it preserves edge sharpness, its regional smoothing may sacrifice tissue image textures, which have been recognized as useful imaging biomarkers, and thus it may compromise clinical tasks such as differentiating malignant vs. benign lesions, e.g., lung nodules or colon polyps. This study aims to shift the edge-preserving regional noise smoothing paradigm to texture-preserving framework for LdCT image reconstruction while retaining the advantage of MRF’s neighborhood system on edge preservation. Specifically, we adapted the MRF model to incorporate the image textures of muscle, fat, bone, lung, etc. from previous full-dose CT (FdCT) scan as a priori knowledge for texture-preserving Bayesian reconstruction of current LdCT images. To show the feasibility of the proposed reconstruction framework, experiments using clinical patient scans were conducted. The experimental outcomes showed a dramatic gain by the a priori knowledge for LdCT image reconstruction using the commonly-used Haralick texture measures. Thus, it is conjectured that the texture-preserving LdCT reconstruction has advantages over the edge-preserving regional smoothing paradigm for texture-specific clinical applications. PMID:26561284

  20. Estimating lesion volume in low-dose chest CT: How low can we go?

    NASA Astrophysics Data System (ADS)

    Young, Stefano; McNitt-Gray, Michael F.

    2014-03-01

    Purpose: To examine the potential for dose reduction in chest CT studies where lesion volume is the primary output (e.g. in therapy-monitoring applications). Methods: We added noise to the raw sinogram data from 15 chest exams with lung lesions to simulate a series of reduced-dose scans for each patient. We reconstructed the reduced-dose data on the clinical workstation and imported the resulting image series into our quantitative imaging database for lesion contouring. One reader contoured the lesions (one per patient) at the clinical reference dose (100%) and 8 simulated fractions of the clinical dose (50, 25, 15, 10, 7, 5, 4, and 3%). Dose fractions were hidden from the reader to reduce bias. We compared clinical and reduced-dose volumes in terms of bias error and variability (4x the standard deviation of the percent differences). Results: Averaging over all lesions, the bias error ranged from -0.6% to 10.6%. Variability ranged from 92% at 3% of clinical dose to 54% at 50% of clinical dose. Averaging over only the smaller lesions (<1cm equivalent diameter), bias error ranged from -9.2% to 14.1% and variability ranged from 125% at 3% dose to 33.9% at 50% dose. Conclusions: The reader's variability decreased with dose, especially for smaller lesions. However, these preliminary results are limited by potential recall bias, a small patient cohort, and an overly-simplified task. Therapy monitoring often involves checking for new lesions, which may influence the reader's clinical dose threshold for acceptable performance.

  1. Noise Reduction for Low-Dose Single-Slice Helical CT Sinograms

    PubMed Central

    Wang, Jing; Li, Tianfang; Lu, Hongbing; Liang, Zhengrong

    2006-01-01

    Helical computed tomography (HCT) has several advantages over conventional step-and-shoot CT for imaging a relatively large object, especially for dynamic studies. However, HCT may increase X-ray exposure significantly. This work aims to reduce the radiation by lowering X-ray tube current (mA) and filtering low-mA (or dose) sinogram noise of HCT. The noise reduction method is based on three observations on HCT: (1) the axial sampling of HCT projections is nearly continuous as detection system rotates; (2) the noise distribution in sinogram space is nearly a Gaussian after system calibration (including logarithmic transform); and (3) the relationship between the calibrated data mean and variance can be expressed as an exponential functional across the field-of-view. Based on the second and third observations, a penalized weighted least-squares (PWLS) solution is an optimal choice, where the weight is given by the mean-variance relationship. The first observation encourages the use of Karhunen-Loève (KL) transform along the axial direction because of the associated correlation. In the KL domain, the eigenvalue of each principal component and the derived data variance provide the signal-to-noise ratio (SNR) information, resulting in a SNR-adaptive noise reduction. The KL-PWLS noise-reduction method was implemented analytically for efficient restoration of large volume HCT sinograms. Simulation studies showed a noticeable improvement, in terms of image quality and defect detectability, of the proposed noise-reduction method over the Ordered-Subsets Expectation-Maximization reconstruction and the conventional low-pass noise filtering with optimal cutoff frequency and/or other filter parameters. PMID:16932806

  2. Fast radioactive seed localization in intraoperative cone beam CT for low-dose-rate prostate brachytherapy

    NASA Astrophysics Data System (ADS)

    Hu, Yu-chi; Xiong, Jian-ping; Cohan, Gilad; Zaider, Marco; Mageras, Gig; Zelefsky, Michael

    2013-03-01

    A fast knowledge-based radioactive seed localization method for brachytherapy was developed to automatically localize radioactive seeds in an intraoperative volumetric cone beam CT (CBCT) so that corrections, if needed, can be made during prostate implant surgery. A transrectal ultrasound (TRUS) scan is acquired for intraoperative treatment planning. Planned seed positions are transferred to intraoperative CBCT following TRUS-to-CBCT registration using a reference CBCT scan of the TRUS probe as a template, in which the probe and its external fiducial markers are pre-segmented and their positions in TRUS are known. The transferred planned seeds and probe serve as an atlas to reduce the search space in CBCT. Candidate seed voxels are identified based on image intensity. Regions are grown from candidate voxels and overlay regions are merged. Region volume and intensity variance is checked against known seed volume and intensity profile. Regions meeting the above criteria are flagged as detected seeds; otherwise they are flagged as likely seeds and sorted by a score that is based on volume, intensity profile and distance to the closest planned seed. A graphical interface allows users to review and accept or reject likely seeds. Likely seeds with approximately twice the seed volume are automatically split. Five clinical cases are tested. Without any manual correction in seed detection, the method performed the localization in 5 seconds (excluding registration time) for a CBCT scan with 512×512×192 voxels. The average precision rate per case is 99% and the recall rate is 96% for a total of 416 seeds. All false negative seeds are found with 15 in likely seeds and 1 included in a detected seed. With the new method, updating of calculations of dose distribution during the procedure is possible and thus facilitating evaluation and improvement of treatment quality.

  3. Task-based image quality evaluation of iterative reconstruction methods for low dose CT using computer simulations.

    PubMed

    Xu, Jingyan; Fuld, Matthew K; Fung, George S K; Tsui, Benjamin M W

    2015-04-01

    Iterative reconstruction (IR) methods for x-ray CT is a promising approach to improve image quality or reduce radiation dose to patients. The goal of this work was to use task based image quality measures and the channelized Hotelling observer (CHO) to evaluate both analytic and IR methods for clinical x-ray CT applications. We performed realistic computer simulations at five radiation dose levels, from a clinical reference low dose D0 to 25% D0. A fixed size and contrast lesion was inserted at different locations into the liver of the XCAT phantom to simulate a weak signal. The simulated data were reconstructed on a commercial CT scanner (SOMATOM Definition Flash; Siemens, Forchheim, Germany) using the vendor-provided analytic (WFBP) and IR (SAFIRE) methods. The reconstructed images were analyzed by CHOs with both rotationally symmetric (RS) and rotationally oriented (RO) channels, and with different numbers of lesion locations (5, 10, and 20) in a signal known exactly (SKE), background known exactly but variable (BKEV) detection task. The area under the receiver operating characteristic curve (AUC) was used as a summary measure to compare the IR and analytic methods; the AUC was also used as the equal performance criterion to derive the potential dose reduction factor of IR. In general, there was a good agreement in the relative AUC values of different reconstruction methods using CHOs with RS and RO channels, although the CHO with RO channels achieved higher AUCs than RS channels. The improvement of IR over analytic methods depends on the dose level. The reference dose level D0 was based on a clinical low dose protocol, lower than the standard dose due to the use of IR methods. At 75% D0, the performance improvement was statistically significant (p < 0.05). The potential dose reduction factor also depended on the detection task. For the SKE/BKEV task involving 10 lesion locations, a dose reduction of at least 25% from D0 was achieved. PMID:25776521

  4. A Model of Regularization Parameter Determination in Low-Dose X-Ray CT Reconstruction Based on Dictionary Learning

    PubMed Central

    Zhang, Cheng; Zhang, Tao; Zheng, Jian; Li, Ming; Lu, Yanfei; You, Jiali; Guan, Yihui

    2015-01-01

    In recent years, X-ray computed tomography (CT) is becoming widely used to reveal patient's anatomical information. However, the side effect of radiation, relating to genetic or cancerous diseases, has caused great public concern. The problem is how to minimize radiation dose significantly while maintaining image quality. As a practical application of compressed sensing theory, one category of methods takes total variation (TV) minimization as the sparse constraint, which makes it possible and effective to get a reconstruction image of high quality in the undersampling situation. On the other hand, a preliminary attempt of low-dose CT reconstruction based on dictionary learning seems to be another effective choice. But some critical parameters, such as the regularization parameter, cannot be determined by detecting datasets. In this paper, we propose a reweighted objective function that contributes to a numerical calculation model of the regularization parameter. A number of experiments demonstrate that this strategy performs well with better reconstruction images and saving of a large amount of time. PMID:26550024

  5. SU-D-12A-06: A Comprehensive Parameter Analysis for Low Dose Cone-Beam CT Reconstruction

    SciTech Connect

    Lu, W; Yan, H; Gu, X; Jiang, S; Jia, X; Bai, T; Zhou, L

    2014-06-01

    Purpose: There is always a parameter in compressive sensing based iterative reconstruction (IR) methods low dose cone-beam CT (CBCT), which controls the weight of regularization relative to data fidelity. A clear understanding of the relationship between image quality and parameter values is important. The purpose of this study is to investigate this subject based on experimental data and a representative advanced IR algorithm using Tight-frame (TF) regularization. Methods: Three data sets of a Catphan phantom acquired at low, regular and high dose levels are used. For each tests, 90 projections covering a 200-degree scan range are used for reconstruction. Three different regions-of-interest (ROIs) of different contrasts are used to calculate contrast-to-noise ratios (CNR) for contrast evaluation. A single point structure is used to measure modulation transfer function (MTF) for spatial-resolution evaluation. Finally, we analyze CNRs and MTFs to study the relationship between image quality and parameter selections. Results: It was found that: 1) there is no universal optimal parameter. The optimal parameter value depends on specific task and dose level. 2) There is a clear trade-off between CNR and resolution. The parameter for the best CNR is always smaller than that for the best resolution. 3) Optimal parameters are also dose-specific. Data acquired under a high dose protocol require less regularization, yielding smaller optimal parameter values. 4) Comparing with conventional FDK images, TF-based CBCT images are better under a certain optimally selected parameters. The advantages are more obvious for low dose data. Conclusion: We have investigated the relationship between image quality and parameter values in the TF-based IR algorithm. Preliminary results indicate optimal parameters are specific to both the task types and dose levels, providing guidance for selecting parameters in advanced IR algorithms. This work is supported in part by NIH (1R01CA154747-01)

  6. In Vivo Comparison of Radiation Exposure of Dual-Energy CT Versus Low-Dose CT Versus Standard CT for Imaging Urinary Calculi

    PubMed Central

    Jepperson, Maria A.; Cernigliaro, Joseph G.; Ibrahim, El-Sayed H.; Morin, Richard L.; Haley, William E.

    2015-01-01

    Abstract Purpose: Dual-energy computed tomography (DECT) is an emerging imaging modality with the unique capability of determining urinary stone composition. This study compares radiation exposure of DECT, standard single-energy CT (SECT), and low-dose renal stone protocol single-energy CT (LDSECT) for the evaluation of nephrolithiasis in a single in vivo patient cohort. Materials and Methods: Following institutional review board (IRB) approval, we retrospectively reviewed 200 consecutive DECT examinations performed on patients with suspected urolithiasis over a 6-month period. Of these, 35 patients had undergone examination with our LDSECT protocol, and 30 patients had undergone examination of the abdomen and pelvis with our SECT imaging protocol within 2 years of the DECT examination. The CT dose index volume (CTDIvol) was used to compare radiation exposure between scans. Image quality was objectively evaluated by comparing image noise. Statistical evaluation was performed using a Student's t-test. Results: DECT performed at 80/140 kVp and 100/140 kVp did not produce a significant difference in radiation exposure compared with LDSECT (p=0.09 and 0.18, respectively). DECT performed at 80/140 kVp and 100/140 kVp produced an average 40% and 31%, respectively, reduction in radiation exposure compared with SECT (p<0.001). For patients imaged with the 100/140 kVp protocol, average values for images noise were higher in the LDSECT images compared with DECT images (p<0.001) and there was no significant difference in image noise between DECT and SECT images in the same patient (p=0.88). Patients imaged with the 80/140 kVp protocol had equivocal image noise compared with LDSECT images (p=0.44), however, DECT images had greater noise compared with SECT images in the same patient (p<0.001). Of the 75 patients included in the study, stone material was available for 16; DECT analysis correctly predicted stone composition in 15/16 patients (93%). Conclusion: DECT

  7. Coronary artery calcium quantification from contrast enhanced CT using gemstone spectral imaging and material decomposition.

    PubMed

    Fuchs, Tobias A; Stehli, Julia; Dougoud, Svetlana; Sah, Bert-Ram; Bull, Sacha; Clerc, Olivier F; Possner, Mathias; Buechel, Ronny R; Gaemperli, Oliver; Kaufmann, Philipp A

    2014-10-01

    To explore the feasibility of coronary artery calcium (CAC) measurement from low-dose contrast enhanced coronary CT angiography (CCTA) as this may obviate the need for an unenhanced CT scan. 52 patients underwent unenhanced cardiac CT and prospectively ECG triggered contrast enhanced CCTA (Discovery HD 750, GE Healthcare, Milwaukee, WI, USA). The latter was acquired in single-source dual-energy mode [gemstone spectral imaging (GSI)]. Virtual unenhanced images were generated from GSI CCTA by monochromatic image reconstruction of 70 keV allowing selective iodine material suppression. CAC scores from virtual unenhanced CT were compared to standard unenhanced CT including a linear regression model. After iodine subtraction from the contrast enhanced CCTA the attenuation in the ascending aorta decreased significantly from 359 ± 61 to 54 ± 8 HU (P < 0.001), the latter comparing well to the value of 64 ± 55 HU found in the standard unenhanced CT (P = ns) confirming successful iodine subtraction. After introducing linear regression formula the mean values for Agatston, Volume and Mass scores of virtual unenhanced CT were 187 ± 321, 72 ± 114 mm(3), and 27 ± 46 mg/cm(3), comparing well to the values from standard unenhanced CT (187 ± 309, 72 ± 110 mm(3), and 27 ± 45 mg/cm(3)) yielding an excellent correlation (r = 0.96, r = 0.96, r = 0.92; P < 0.001). Mean estimated radiation dose revealed 0.83 ± 0.02 mSv from the unenhanced CT and 1.70 ± 0.53 mSv from the contrast enhanced CCTA. Single-source dual-energy scanning with GSI allows CAC quantification from low dose contrast enhanced CCTA by virtual iodine contrast subtraction. PMID:24993390

  8. Automated detection of nodules attached to the pleural and mediastinal surface in low-dose CT scans

    NASA Astrophysics Data System (ADS)

    van Ginneken, Bram; Tan, Andre; Murphy, Keelin; de Hoop, Bart-Jan; Prokop, Mathias

    2008-03-01

    This paper presents a new computer-aided detection scheme for lung nodules attached to the pleural or mediastinal surface in low dose CT scans. First the lungs are automatically segmented and smoothed. Any connected set of voxels attached to the wall - with each voxel above minus 500 HU and the total object within a specified volume range - was considered a candidate finding. For each candidate, a refined segmentation was computed using morphological operators to remove attached structures. For each candidate, 35 features were defined, based on their position in the lung and relative to other structures, and the shape and density within and around each candidate. In a training procedure an optimal set of 15 features was determined with a k-nearest-neighbor classifier and sequential floating forward feature selection. The algorithm was trained with a data set of 708 scans from a lung cancer screening study containing 224 pleural nodules and tested on an independent test set of 226 scans from the same program with 58 pleural nodules. The algorithm achieved a sensitivity of 52% with an average of 0.76 false positives per scan. At 2.5 false positive marks per scan, the sensitivity increased to 80%.

  9. Lung Cancer Screening With Low-Dose CT: Implementation Amid Changing Public Policy at One Health Care System.

    PubMed

    Begnaud, Abbie; Hall, Thomas; Allen, Tadashi

    2016-01-01

    Screening for lung cancer with low-dose CT has evolved rapidly in recent years since the National Lung Screening Trial (NLST) results. Subsequent professional and governmental organization guidelines have shaped policy and reimbursement for the service. Increasingly available guidance describes eligible patients and components necessary for a high-quality lung cancer screening program; however, practical instruction and implementation experience is not widely reported. We launched a lung cancer screening program in the face of reimbursement and guideline uncertainties at a large academic health center. We report our experience with implementation, including challenges and proposed solutions. Initially, we saw less referrals than expected for screening, and many patients referred for screening did not clearly meet eligibility guidelines. We educated primary care providers and implemented system tools to encourage referral of eligible patients. Moreover, in response to the Centers for Medicare & Medicaid Services (CMS) final coverage determination, we report our programmatic adaptation to meet these requirements. In addition to the components common to all quality programs, individual health delivery systems will face unique barriers related to patient population, available resources, and referral patterns. PMID:27249755

  10. Non-osseous incidental findings in low-dose whole-body CT in patients with multiple myeloma

    PubMed Central

    Bach, A G; Tcherkes, A; Schramm, D

    2014-01-01

    Objective: The purpose of this study was to identify the frequency and grading of non-osseous incidental findings (NOIF) in non-contrast whole-body low-dose CT (LDCT) in patients with multiple myeloma. Methods: In the time period from 2010 to 2013, 93 patients with multiple myeloma were staged by non-contrast whole-body LDCT at our radiological department. LDCT images were analysed retrospectively for NOIF, which also included unsuspected extramedullary manifestation of multiple myeloma. All NOIF were classified as major or clinically significant, moderate or possibly clinically significant and minor or not clinically significant. Medical records were analysed regarding further investigation and follow-up of the identified NOIF. Results: In the 93 patients, 295 NOIF were identified (on average, 3.2 NOIF per patient). Most of the NOIF (52.4%) were not clinically significant, 25.8% of the NOIF were possibly clinically significant and 21.8% of the NOIF were clinically significant. Clinically significant NOIF were investigated further by CT after intravenous administration of contrast medium and/or by ultrasound or MRI. In 34 of these cases, extramedullary relapse of myeloma, occult carcinoma or infectious/septic incidental findings were diagnosed (11.5% of all NOIF). In the remaining 10.3% of the NOIF classified as clinically significant, various benign lesions were diagnosed. Conclusion: LDCT detected various non-osseous lesions in patients with multiple myeloma. 36.6% of the patients had clinically significant NOIF. Therefore, LDCT examinations in patients with multiple myeloma should be evaluated carefully for the presence of NOIF. Advances in knowledge: LDCT identified several NOIF. A total of 36.6% of patients with multiple myeloma had clinically significant NOIF. Radiologists should analyse LDCT examinations in patients with multiple myeloma not only for bone lesions, but also for lesions in other organs. PMID:25004949

  11. Low-dose preview for patient-specific, task-specific technique selection in cone-beam CT

    PubMed Central

    Wang, Adam S.; Stayman, J. Webster; Otake, Yoshito; Vogt, Sebastian; Kleinszig, Gerhard; Khanna, A. Jay; Gallia, Gary L.; Siewerdsen, Jeffrey H.

    2014-01-01

    Purpose : A method is presented for generating simulated low-dose cone-beam CT (CBCT) preview images from which patient- and task-specific minimum-dose protocols can be confidently selected prospectively in clinical scenarios involving repeat scans. Methods : In clinical scenarios involving a series of CBCT images, the low-dose preview (LDP) method operates upon the first scan to create a projection dataset that accurately simulates the effects of dose reduction in subsequent scans by injecting noise of proper magnitude and correlation, including both quantum and electronic readout noise as important components of image noise in flat-panel detector CBCT. Experiments were conducted to validate the LDP method in both a head phantom and a cadaveric torso by performing CBCT acquisitions spanning a wide dose range (head: 0.8–13.2 mGy, body: 0.8–12.4 mGy) with a prototype mobile C-arm system. After injecting correlated noise to simulate dose reduction, the projections were reconstructed using both conventional filtered backprojection (FBP) and an iterative, model-based image reconstruction method (MBIR). The LDP images were then compared to real CBCT images in terms of noise magnitude, noise-power spectrum (NPS), spatial resolution, contrast, and artifacts. Results : For both FBP and MBIR, the LDP images exhibited accurate levels of spatial resolution and contrast that were unaffected by the correlated noise injection, as expected. Furthermore, the LDP image noise magnitude and NPS were in strong agreement with real CBCT images acquired at the corresponding, reduced dose level across the entire dose range considered. The noise magnitude agreed within 7% for both the head phantom and cadaveric torso, and the NPS showed a similar level of agreement up to the Nyquist frequency. Therefore, the LDP images were highly representative of real image quality across a broad range of dose and reconstruction methods. On the other hand, naïve injection ofuncorrelated noise

  12. Low-dose preview for patient-specific, task-specific technique selection in cone-beam CT

    SciTech Connect

    Wang, Adam S.; Stayman, J. Webster; Otake, Yoshito; Siewerdsen, Jeffrey H.; Vogt, Sebastian; Kleinszig, Gerhard; Khanna, A. Jay; Gallia, Gary L.

    2014-07-15

    Purpose : A method is presented for generating simulated low-dose cone-beam CT (CBCT) preview images from which patient- and task-specific minimum-dose protocols can be confidently selected prospectively in clinical scenarios involving repeat scans. Methods : In clinical scenarios involving a series of CBCT images, the low-dose preview (LDP) method operates upon the first scan to create a projection dataset that accurately simulates the effects of dose reduction in subsequent scans by injecting noise of proper magnitude and correlation, including both quantum and electronic readout noise as important components of image noise in flat-panel detector CBCT. Experiments were conducted to validate the LDP method in both a head phantom and a cadaveric torso by performing CBCT acquisitions spanning a wide dose range (head: 0.8–13.2 mGy, body: 0.8–12.4 mGy) with a prototype mobile C-arm system. After injecting correlated noise to simulate dose reduction, the projections were reconstructed using both conventional filtered backprojection (FBP) and an iterative, model-based image reconstruction method (MBIR). The LDP images were then compared to real CBCT images in terms of noise magnitude, noise-power spectrum (NPS), spatial resolution, contrast, and artifacts. Results : For both FBP and MBIR, the LDP images exhibited accurate levels of spatial resolution and contrast that were unaffected by the correlated noise injection, as expected. Furthermore, the LDP image noise magnitude and NPS were in strong agreement with real CBCT images acquired at the corresponding, reduced dose level across the entire dose range considered. The noise magnitude agreed within 7% for both the head phantom and cadaveric torso, and the NPS showed a similar level of agreement up to the Nyquist frequency. Therefore, the LDP images were highly representative of real image quality across a broad range of dose and reconstruction methods. On the other hand, naïve injection ofuncorrelated noise

  13. Over-exposure correction in knee cone-beam CT imaging with automatic exposure control using a partial low dose scan

    NASA Astrophysics Data System (ADS)

    Choi, Jang-Hwan; Muller, Kerstin; Hsieh, Scott; Maier, Andreas; Gold, Garry; Levenston, Marc; Fahrig, Rebecca

    2016-03-01

    C-arm-based cone-beam CT (CBCT) systems with flat-panel detectors are suitable for diagnostic knee imaging due to their potentially flexible selection of CT trajectories and wide volumetric beam coverage. In knee CT imaging, over-exposure artifacts can occur because of limitations in the dynamic range of the flat panel detectors present on most CBCT systems. We developed a straightforward but effective method for correction and detection of over-exposure for an Automatic Exposure Control (AEC)-enabled standard knee scan incorporating a prior low dose scan. The radiation dose associated with the low dose scan was negligible (0.0042mSv, 2.8% increase) which was enabled by partially sampling the projection images considering the geometry of the knees and lowering the dose further to be able to just see the skin-air interface. We combined the line integrals from the AEC and low dose scans after detecting over-exposed regions by comparing the line profiles of the two scans detector row-wise. The combined line integrals were reconstructed into a volumetric image using filtered back projection. We evaluated our method using in vivo human subject knee data. The proposed method effectively corrected and detected over-exposure, and thus recovered the visibility of exterior tissues (e.g., the shape and density of the patella, and the patellar tendon), incorporating a prior low dose scan with a negligible increase in radiation exposure.

  14. Motion-compensated PET image reconstruction with respiratory-matched attenuation correction using two low-dose inhale and exhale CT images

    NASA Astrophysics Data System (ADS)

    Nam, Woo Hyun; Ahn, Il Jun; Kim, Kyeong Min; Kim, Byung Il; Ra, Jong Beom

    2013-10-01

    Positron emission tomography (PET) is widely used for diagnosis and follow up assessment of radiotherapy. However, thoracic and abdominal PET suffers from false staging and incorrect quantification of the radioactive uptake of lesion(s) due to respiratory motion. Furthermore, respiratory motion-induced mismatch between a computed tomography (CT) attenuation map and PET data often leads to significant artifacts in the reconstructed PET image. To solve these problems, we propose a unified framework for respiratory-matched attenuation correction and motion compensation of respiratory-gated PET. For the attenuation correction, the proposed algorithm manipulates a 4D CT image virtually generated from two low-dose inhale and exhale CT images, rather than a real 4D CT image which significantly increases the radiation burden on a patient. It also utilizes CT-driven motion fields for motion compensation. To realize the proposed algorithm, we propose an improved region-based approach for non-rigid registration between body CT images, and we suggest a selection scheme of 3D CT images that are respiratory-matched to each respiratory-gated sinogram. In this work, the proposed algorithm was evaluated qualitatively and quantitatively by using patient datasets including lung and/or liver lesion(s). Experimental results show that the method can provide much clearer organ boundaries and more accurate lesion information than existing algorithms by utilizing two low-dose CT images.

  15. Image quality in low-dose coronary computed tomography angiography with a new high-definition CT scanner.

    PubMed

    Kazakauskaite, Egle; Husmann, Lars; Stehli, Julia; Fuchs, Tobias; Fiechter, Michael; Klaeser, Bernd; Ghadri, Jelena R; Gebhard, Catherine; Gaemperli, Oliver; Kaufmann, Philipp A

    2013-02-01

    A new generation of high definition computed tomography (HDCT) 64-slice devices complemented by a new iterative image reconstruction algorithm-adaptive statistical iterative reconstruction, offer substantially higher resolution compared to standard definition CT (SDCT) scanners. As high resolution confers higher noise we have compared image quality and radiation dose of coronary computed tomography angiography (CCTA) from HDCT versus SDCT. Consecutive patients (n = 93) underwent HDCT, and were compared to 93 patients who had previously undergone CCTA with SDCT matched for heart rate (HR), HR variability and body mass index (BMI). Tube voltage and current were adapted to the patient's BMI, using identical protocols in both groups. The image quality of all CCTA scans was evaluated by two independent readers in all coronary segments using a 4-point scale (1, excellent image quality; 2, blurring of the vessel wall; 3, image with artefacts but evaluative; 4, non-evaluative). Effective radiation dose was calculated from DLP multiplied by a conversion factor (0.014 mSv/mGy × cm). The mean image quality score from HDCT versus SDCT was comparable (2.02 ± 0.68 vs. 2.00 ± 0.76). Mean effective radiation dose did not significantly differ between HDCT (1.7 ± 0.6 mSv, range 1.0-3.7 mSv) and SDCT (1.9 ± 0.8 mSv, range 0.8-5.5 mSv; P = n.s.). HDCT scanners allow low-dose 64-slice CCTA scanning with higher resolution than SDCT but maintained image quality and equally low radiation dose. Whether this will translate into higher accuracy of HDCT for CAD detection remains to be evaluated. PMID:22825255

  16. TU-A-12A-09: Absolute Blood Flow Measurement in a Cardiac Phantom Using Low Dose CT

    SciTech Connect

    Ziemer, B; Hubbard, L; Lipinski, J; Molloi, S

    2014-06-15

    Purpose: To investigate a first pass analysis technique to measure absolute flow from low dose CT images in a cardiac phantom. This technique can be combined with a myocardial mass assignment to yield absolute perfusion using only two volume scans and reduce the radiation dose to the patient. Methods: A four-chamber cardiac phantom and perfusion chamber were constructed from poly-acrylic and connected with tubing to approximate anatomical features. The system was connected to a pulsatile pump, input/output reservoirs and power contrast injector. Flow was varied in the range of 1-2.67 mL/s with the pump operating at 60 beats/min. The system was imaged once a second for 14 seconds with a 320-row scanner (Toshiba Medical Systems) using a contrast-enhanced, prospective-gated cardiac perfusion protocol. Flow was calculated by the following steps: subsequent images of the perfusion volume were subtracted to find the contrast entering the volume; this was normalized by an upstream, known volume region to convert Hounsfield (HU) values to concentration; this was divided by the subtracted images time difference. The technique requires a relatively stable input contrast concentration and no contrast can leave the perfusion volume before the flow measurement is completed. Results: The flow calculated from the images showed an excellent correlation with the known rates. The data was fit to a linear function with slope 1.03, intercept 0.02 and an R{sup 2} value of 0.99. The average root mean square (RMS) error was 0.15 mL/s and the average standard deviation was 0.14 mL/s. The flow rate was stable within 7.7% across the full scan and served to validate model assumptions. Conclusion: Accurate, absolute flow rates were measured from CT images using a conservation of mass model. Measurements can be made using two volume scans which can substantially reduce the radiation dose compared with current dynamic perfusion techniques.

  17. Texture-preserved penalized weighted least-squares reconstruction of low-dose CT image via image segmentation and high-order MRF modeling

    NASA Astrophysics Data System (ADS)

    Han, Hao; Zhang, Hao; Wei, Xinzhou; Moore, William; Liang, Zhengrong

    2016-03-01

    In this paper, we proposed a low-dose computed tomography (LdCT) image reconstruction method with the help of prior knowledge learning from previous high-quality or normal-dose CT (NdCT) scans. The well-established statistical penalized weighted least squares (PWLS) algorithm was adopted for image reconstruction, where the penalty term was formulated by a texture-based Gaussian Markov random field (gMRF) model. The NdCT scan was firstly segmented into different tissue types by a feature vector quantization (FVQ) approach. Then for each tissue type, a set of tissue-specific coefficients for the gMRF penalty was statistically learnt from the NdCT image via multiple-linear regression analysis. We also proposed a scheme to adaptively select the order of gMRF model for coefficients prediction. The tissue-specific gMRF patterns learnt from the NdCT image were finally used to form an adaptive MRF penalty for the PWLS reconstruction of LdCT image. The proposed texture-adaptive PWLS image reconstruction algorithm was shown to be more effective to preserve image textures than the conventional PWLS image reconstruction algorithm, and we further demonstrated the gain of high-order MRF modeling for texture-preserved LdCT PWLS image reconstruction.

  18. SU-E-I-86: Ultra-Low Dose Computed Tomography Attenuation Correction for Pediatric PET CT Using Adaptive Statistical Iterative Reconstruction (ASiR™)

    SciTech Connect

    Brady, S; Shulkin, B

    2015-06-15

    Purpose: To develop ultra-low dose computed tomography (CT) attenuation correction (CTAC) acquisition protocols for pediatric positron emission tomography CT (PET CT). Methods: A GE Discovery 690 PET CT hybrid scanner was used to investigate the change to quantitative PET and CT measurements when operated at ultra-low doses (10–35 mAs). CT quantitation: noise, low-contrast resolution, and CT numbers for eleven tissue substitutes were analyzed in-phantom. CT quantitation was analyzed to a reduction of 90% CTDIvol (0.39/3.64; mGy) radiation dose from baseline. To minimize noise infiltration, 100% adaptive statistical iterative reconstruction (ASiR) was used for CT reconstruction. PET images were reconstructed with the lower-dose CTAC iterations and analyzed for: maximum body weight standardized uptake value (SUVbw) of various diameter targets (range 8–37 mm), background uniformity, and spatial resolution. Radiation organ dose, as derived from patient exam size specific dose estimate (SSDE), was converted to effective dose using the standard ICRP report 103 method. Effective dose and CTAC noise magnitude were compared for 140 patient examinations (76 post-ASiR implementation) to determine relative patient population dose reduction and noise control. Results: CT numbers were constant to within 10% from the non-dose reduced CTAC image down to 90% dose reduction. No change in SUVbw, background percent uniformity, or spatial resolution for PET images reconstructed with CTAC protocols reconstructed with ASiR and down to 90% dose reduction. Patient population effective dose analysis demonstrated relative CTAC dose reductions between 62%–86% (3.2/8.3−0.9/6.2; mSv). Noise magnitude in dose-reduced patient images increased but was not statistically different from pre dose-reduced patient images. Conclusion: Using ASiR allowed for aggressive reduction in CTAC dose with no change in PET reconstructed images while maintaining sufficient image quality for co

  19. MicroPET/CT Imaging of an Orthotopic Model of Human Glioblastoma Multiforme and Evaluation of Pulsed Low-Dose Irradiation

    SciTech Connect

    Park, Sean S.; Chunta, John L.; Robertson, John M.; Martinez, Alvaro A.; Oliver Wong, Ching-Yee; Amin, Mitual; Wilson, George D.; Marples, Brian

    2011-07-01

    Purpose: Glioblastoma multiforme (GBM) is an aggressive tumor that typically causes death due to local progression. To assess a novel low-dose radiotherapy regimen for treating GBM, we developed an orthotopic murine model of human GBM and evaluated in vivo treatment efficacy using micro-positron-emission tomography/computed tomography (microPET/CT) tumor imaging. Methods: Orthotopic GBM xenografts were established in nude mice and treated with standard 2-Gy fractionation or 10 0.2-Gy pulses with 3-min interpulse intervals, for 7 consecutive days, for a total dose of 14 Gy. Tumor growth was quantified weekly using the Flex Triumph (GE Healthcare/Gamma Medica-Ideas, Waukesha, WI) combined PET-single-photon emission CT (SPECT)-CT imaging system and necropsy histopathology. Normal tissue damage was assessed by counting dead neural cells in tissue sections from irradiated fields. Results: Tumor engraftment efficiency for U87MG cells was 86%. Implanting 0.5 x 10{sup 6} cells produced a 50- to 70-mm{sup 3} tumor in 10 to 14 days. A significant correlation was seen between CT-derived tumor volume and histopathology-measured volume (p = 0.018). The low-dose 0.2-Gy pulsed regimen produced a significantly longer tumor growth delay than standard 2-Gy fractionation (p = 0.045). Less normal neuronal cell death was observed after the pulsed delivery method (p = 0.004). Conclusion: This study successfully demonstrated the feasibility of in vivo brain tumor imaging and longitudinal assessment of tumor growth and treatment response with microPET/CT. Pulsed radiation treatment was more efficacious than the standard fractionated treatment and was associated with less normal tissue damage.

  20. Evaluation of implant loosening following segmental pedicle screw fixation in adolescent idiopathic scoliosis: a 2 year follow-up with low-dose CT

    PubMed Central

    2014-01-01

    Background The long term radiological status of screw fixation following scoliosis surgery with all pedicle screw construct is not previously studied. Aim To evaluate the incidence of loosening (implant failure) evaluated with low-dose CT two years following scoliosis surgery. Study design Retrospective study. Methods 81 consecutive patients with adolescent idiopathic scoliosis (AIS), aged 18 ± 3 years at 2 years follow-up (83% were female), subjected for scoliosis corrective surgery with all pedicle screw construct (total of 1666 screws) has been examined with plain radiography and with low dose CT 6 weeks and 2 years postoperatively. Results In 26 out of 81 (32%) patients there were signs of loosening of one or more screws, a maximum 3 screws. 47 out of 1666 (2.8%) screws showed evidence of loosening. Preoperative Cobb angle was 56° among patients with loosening compared with 53° among patients with no evidence of loosening (P = 0.288). In males there were signs of loosening in 8 out of 14 (57%) and in females 18 out of 67 (27%), (P = 0.027). Among cases with loosening, 14% had suboptimal screw placement at the first postoperative CT compared with 11% among patients with no evidence of loosening (P = 0.254). One patient with a loosened L4 screw had neurological deficit and subjected for revision of the construct. Out of 26 patients with evidence of loosening, 5 patients reported minor pain or discomfort, 1 patient had a minor proximal junctional kyphosis of about 15° and 3 patients showed evidence of pull-out of 3–5 mm at the upper end of the construct but no clinical complaint. With plain radiography loosening could be observed only in 11 out of 26 cases, 5 were in the lumbar region. Conclusions In a consecutive series of 81 cases with AIS who had underwent scoliosis surgery, one third showed, 2 years after the intervention, minor screw loosening. Males were more prone to develop screw loosening. In CT system that enables low-dose

  1. Low-dose CT of the paranasal sinuses with eye lens protection: effect on image quality and radiation dose.

    PubMed

    Hein, Eike; Rogalla, Patrik; Klingebiel, Randolph; Hamm, Bernd

    2002-07-01

    The purpose of the study was to assess the effect of lens protection on image quality and radiation dose to the eye lenses in CT of the paranasal sinuses. In 127 patients referred to rule out sinusitis, an axial spiral CT with a lens protection placed on the patients eyes was obtained (1.5/2/1, 50 mAs, 120 kV). Coronal views were reconstructed at 5-mm interval. To quantify a subjective impression of image quality, three regions of interest within the eyeball were plotted along a line perpendicular to the protection at 2, 5, and 9 mm beneath skin level on the axial images. Additionally, dose reduction of a bismuth-containing latex shield was measured using a film-dosimetry technique. The average eyeball density was 17.97 HU (SD 3.7 HU). The relative increase in CT density was 180.6 (17.7), 103.3 (11.7), and 53.6 HU (9.2), respectively. There was no diagnostic information loss on axial and coronal views observed. Artifacts were practically invisible on images viewed in a bone window/level setting. The use of the shield reduced skin radiation from 7.5 to 4.5 mGy. The utilization of a radioprotection to the eye lenses in paranasal CT is a suitable and effective means of reducing skin radiation by 40%. PMID:12111059

  2. Assessment of dedicated low-dose cardiac micro-CT reconstruction algorithms using the left ventricular volume of small rodents as a performance measure

    SciTech Connect

    Maier, Joscha; Sawall, Stefan; Kachelrieß, Marc

    2014-05-15

    Purpose: Phase-correlated microcomputed tomography (micro-CT) imaging plays an important role in the assessment of mouse models of cardiovascular diseases and the determination of functional parameters as the left ventricular volume. As the current gold standard, the phase-correlated Feldkamp reconstruction (PCF), shows poor performance in case of low dose scans, more sophisticated reconstruction algorithms have been proposed to enable low-dose imaging. In this study, the authors focus on the McKinnon-Bates (MKB) algorithm, the low dose phase-correlated (LDPC) reconstruction, and the high-dimensional total variation minimization reconstruction (HDTV) and investigate their potential to accurately determine the left ventricular volume at different dose levels from 50 to 500 mGy. The results were verified in phantom studies of a five-dimensional (5D) mathematical mouse phantom. Methods: Micro-CT data of eight mice, each administered with an x-ray dose of 500 mGy, were acquired, retrospectively gated for cardiac and respiratory motion and reconstructed using PCF, MKB, LDPC, and HDTV. Dose levels down to 50 mGy were simulated by using only a fraction of the projections. Contrast-to-noise ratio (CNR) was evaluated as a measure of image quality. Left ventricular volume was determined using different segmentation algorithms (Otsu, level sets, region growing). Forward projections of the 5D mouse phantom were performed to simulate a micro-CT scan. The simulated data were processed the same way as the real mouse data sets. Results: Compared to the conventional PCF reconstruction, the MKB, LDPC, and HDTV algorithm yield images of increased quality in terms of CNR. While the MKB reconstruction only provides small improvements, a significant increase of the CNR is observed in LDPC and HDTV reconstructions. The phantom studies demonstrate that left ventricular volumes can be determined accurately at 500 mGy. For lower dose levels which were simulated for real mouse data sets, the

  3. SU-E-I-41: Dictionary Learning Based Quantitative Reconstruction for Low-Dose Dual-Energy CT (DECT)

    SciTech Connect

    Xu, Q; Xing, L; Xiong, G; Elmore, K; Min, J

    2015-06-15

    Purpose: DECT collects two sets of projection data under higher and lower energies. With appropriates composition methods on linear attenuation coefficients, quantitative information about the object, such as density, can be obtained. In reality, one of the important problems in DECT is the radiation dose due to doubled scans. This work is aimed at establishing a dictionary learning based reconstruction framework for DECT for improved image quality while reducing the imaging dose. Methods: In our method, two dictionaries were learned respectively from the high-energy and lowenergy image datasets of similar objects under normal dose in advance. The linear attenuation coefficient was decomposed into two basis components with material based composition method. An iterative reconstruction framework was employed. Two basis components were alternately updated with DECT datasets and dictionary learning based sparse constraints. After one updating step under the dataset fidelity constraints, both high-energy and low-energy images can be obtained from the two basis components. Sparse constraints based on the learned dictionaries were applied to the high- and low-energy images to update the two basis components. The iterative calculation continues until a pre-set number of iteration was reached. Results: We evaluated the proposed dictionary learning method with dual energy images collected using a DECT scanner. We re-projected the projection data with added Poisson noise to reflect the low-dose situation. The results obtained by the proposed method were compared with that obtained using FBP based method and TV based method. It was found that the proposed approach yield better results than other methods with higher resolution and less noise. Conclusion: The use of dictionary learned from DECT images under normal dose is valuable and leads to improved results with much lower imaging dose.

  4. Low dose, low noise, and high resolution volume of interest (VOI) imaging in C-arm flat-detector CT

    NASA Astrophysics Data System (ADS)

    Kolditz, Daniel; Kyriakou, Yiannis; Kalender, Willi A.

    2010-04-01

    The high flexibility of C-arm flat-detector computed tomography (FDCT) is used in a volume of interest (VOI) imaging method to handle the challenges of increasing spatial resolution, reducing noise and saving dose. A low-dose overview scan of the object and a high-dose scan of an arbitrary VOI are combined. The first scan is adequate for orientation to select the VOI and the second scan assures high image quality in the VOI. The combination is based on a forward projection of the reconstructed overview volume and the measured VOI data in the raw data domain. Differences in the projection values are matched before a standard Feldkamp-type reconstruction is performed. In simulations, spatial resolution, noise and contrast detectability were evaluated. Measurements of an anthropomorphic phantom were used to validate the proposed method for realistic application. In Monte Carlo dose simulations the dose reduction potential was investigated. By combination of the two scans an image is generated which covers the whole object and provides the actual VOI at high image quality. Spatial resolution was increased whereas noise was decreased from outside to inside the VOI, e.g. for the simulations from 0.8 lp/mm to 3.0 lp/mm and from 39 HU to 18 HU, respectively. Simultaneously, the cumulative dose for this two-scan procedure was significantly reduced in comparison to a conventional high dose scan, e.g. for the performed simulations and measurements by about 95 %. The proposed VOI approach offers significant benefits with respect to high-resolution and low-contrast imaging of a VOI at reduced dose.

  5. Sparse-view image reconstruction in inverse-geometry CT (IGCT) for fast, low-dose, volumetric dental X-ray imaging

    NASA Astrophysics Data System (ADS)

    Hong, D. K.; Cho, H. S.; Oh, J. E.; Je, U. K.; Lee, M. S.; Kim, H. J.; Lee, S. H.; Park, Y. O.; Choi, S. I.; Koo, Y. S.; Cho, H. M.

    2012-12-01

    As a new direction for computed tomography (CT) imaging, inverse-geometry CT (IGCT) has been recently introduced and is intended to overcome limitations in conventional cone-beam CT (CBCT) such as the cone-beam artifacts, imaging dose, temporal resolution, scatter, cost, and so on. While the CBCT geometry consists of X-rays emanating from a small focal spot and collimated toward a larger detector, the IGCT geometry employs a large-area scanned source array with the Xray beams collimated toward a smaller-area detector. In this research, we explored an effective IGCT reconstruction algorithm based on the total-variation (TV) minimization method and studied the feasibility of the IGCT geometry for potential applications to fast, low-dose volumetric dental X-ray imaging. We implemented the algorithm, performed systematic simulation works, and evaluated the imaging characteristics quantitatively. Although much engineering and validation works are required to achieve clinical implementation, our preliminary results have demonstrated a potential for improved volumetric imaging with reduced dose.

  6. Fully automated classification of bone marrow infiltration in low-dose CT of patients with multiple myeloma based on probabilistic density model and supervised learning.

    PubMed

    Martínez-Martínez, Francisco; Kybic, Jan; Lambert, Lukáš; Mecková, Zuzana

    2016-04-01

    This paper presents a fully automated method for the identification of bone marrow infiltration in femurs in low-dose CT of patients with multiple myeloma. We automatically find the femurs and the bone marrow within them. In the next step, we create a probabilistic, spatially dependent density model of normal tissue. At test time, we detect unexpectedly high density voxels which may be related to bone marrow infiltration, as outliers to this model. Based on a set of global, aggregated features representing all detections from one femur, we classify the subjects as being either healthy or not. This method was validated on a dataset of 127 subjects with ground truth created from a consensus of two expert radiologists, obtaining an AUC of 0.996 for the task of distinguishing healthy controls and patients with bone marrow infiltration. To the best of our knowledge, no other automatic image-based method for this task has been published before. PMID:26894595

  7. Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT

    SciTech Connect

    Xia, Y.; Maier, A.; Berger, M.; Hornegger, J.; Bauer, S.

    2015-04-15

    Purpose: Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow. Methods: A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior–posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate. Results: The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on

  8. Very low-dose adult whole-body tumor imaging with F-18 FDG PET/CT

    NASA Astrophysics Data System (ADS)

    Krol, Andrzej; Naveed, Muhammad; McGrath, Mary; Lisi, Michele; Lavalley, Cathy; Feiglin, David

    2015-03-01

    The aim of this study was to evaluate if effective radiation dose due to PET component in adult whole-body tumor imaging with time-of-flight F-18 FDG PET/CT could be significantly reduced. We retrospectively analyzed data for 10 patients with the body mass index ranging from 25 to 50. We simulated F-18 FDG dose reduction to 25% of the ACR recommended dose via reconstruction of simulated shorter acquisition time per bed position scans from the acquired list data. F-18 FDG whole-body scans were reconstructed using time-of-flight OSEM algorithm and advanced system modeling. Two groups of images were obtained: group A with a standard dose of F-18 FDG and standard reconstruction parameters and group B with simulated 25% dose and modified reconstruction parameters, respectively. Three nuclear medicine physicians blinded to the simulated activity independently reviewed the images and compared diagnostic quality of images. Based on the input from the physicians, we selected optimal modified reconstruction parameters for group B. In so obtained images, all the lesions observed in the group A were visible in the group B. The tumor SUV values were different in the group A, as compared to group B, respectively. However, no significant differences were reported in the final interpretation of the images from A and B groups. In conclusion, for a small number of patients, we have demonstrated that F-18 FDG dose reduction to 25% of the ACR recommended dose, accompanied by appropriate modification of the reconstruction parameters provided adequate diagnostic quality of PET images acquired on time-of-flight PET/CT.

  9. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    PubMed Central

    Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

    2014-01-01

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

  10. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    SciTech Connect

    Cho, Hyo-Min; Ding, Huanjun; Molloi, Sabee; Barber, William C.; Iwanczyk, Jan S.

    2014-09-15

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A{sup 109}Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm{sup 2}) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy

  11. Double-low protocol for hepatic dynamic CT scan: Effect of low tube voltage and low-dose iodine contrast agent on image quality.

    PubMed

    Zhang, Xiuli; Li, Shaodong; Liu, Wenlou; Huang, Ning; Li, Jingjing; Cheng, Li; Xu, Kai

    2016-06-01

    The radiation-induced carcinogenesis from computed tomography (CT) and iodine contrast agent induced nephropathy has attracted international attention. The reduction of the radiation dose and iodine intake in CT scan is always a direction for researchers to strive. The purpose of this study was to evaluate the feasibility of a "double-low" (i.e., low tube voltage and low-dose iodine contrast agent) scanning protocol for dynamic hepatic CT with the adaptive statistical iterative reconstruction (ASIR) in patients with a body mass index (BMI) of 18.5 to 27.9 kg/m.A total of 128 consecutive patients with a BMI between 18.5 and 27.9 kg/m were randomly assigned into 3 groups according to tube voltage, iodine contrast agent, and reconstruction algorithms. Group A (the "double-low" protocol): 100 kVp tube voltage with 40% ASIR, iodixanol at 270 mg I/mL, group B: 120 kVp tube voltage with filtered back projection (FBP), iodixanol at 270 mg I/ mL, and group C: 120 kVp tube voltage with FBP, ioversol at 350 mg I/ mL.The volume CT dose index (CTDIvol) and effective dose (ED) in group A were lower than those in group B and C (all P < 0.01). The iodine intake in group A was decreased by approximately 26.5% than group C, whereas no statistical difference was observed between group A and B (P > 0.05). There was no significant difference of the CT values between group A and C (P > 0.05), which both showed higher CT values than that in group B (P < 0.001). However, no statistic difference was observed in the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and image-quality scores among the 3 groups (all P > 0.05). Near-perfect consistency of the evaluation for group A, B, and C (Kenall's W = 0.921, 0.874, and 0.949, respectively) was obtained by the 4 readers with respect to the overall image quality.These results suggested that the "double-low" protocol with ASIR algorithm for multi-phase hepatic CT scan can dramatically decrease

  12. Fat quantification and analysis of lung transplant patients on unenhanced chest CT images based on standardized anatomic space

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Torigian, Drew A.; Wu, Caiyun; Christie, Jason; Lederer, David J.

    2016-03-01

    Chest fat estimation is important for identifying high-risk lung transplant candidates. In this paper, an approach to chest fat quantification based on a recently formulated concept of standardized anatomic space (SAS) is presented. The goal of this paper is to seek answers to the following questions related to chest fat quantification on single slice versus whole volume CT, which have not been addressed in the literature. What level of correlation exists between total chest fat volume and fat areas measured on single abdominal and thigh slices? What is the anatomic location in the chest where maximal correlation of fat area with fat volume can be expected? Do the components of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) have the same area-to-volume correlative behavior or do they differ? The SAS approach includes two steps: calibration followed by transformation which will map the patient slice locations non-linearly to SAS. The optimal slice locations found for SAT and VAT based on SAS are different and at the mid-level of the T8 vertebral body for SAT and mid-level of the T7 vertebral body for VAT. Fat volume and area on optimal slices for SAT and VAT are correlated with Pearson correlation coefficients of 0.97 and 0.86, respectively. The correlation of chest fat volume with abdominal and thigh fat areas is weak to modest.

  13. Low kV settings CT angiography (CTA) with low dose contrast medium volume protocol in the assessment of thoracic and abdominal aorta disease: a feasibility study

    PubMed Central

    Talei Franzesi, C; Fior, D; Bonaffini, P A; Minutolo, O; Sironi, S

    2015-01-01

    Objective: To assess the diagnostic quality of low dose (100 kV) CT angiography (CTA), by using ultra-low contrast medium volume (30 ml), for thoracic and abdominal aorta evaluation. Methods: 67 patients with thoracic or abdominal vascular disease underwent multidetector CT study using a 256 slice scanner, with low dose radiation protocol (automated tube current modulation, 100 kV) and low contrast medium volume (30 ml; 4 ml s−1). Density measurements were performed on ascending, arch, descending thoracic aorta, anonymous branch, abdominal aorta, and renal and common iliac arteries. Radiation dose exposure [dose–length product (DLP)] was calculated. A control group of 35 patients with thoracic or abdominal vascular disease were evaluated with standard CTA protocol (automated tube current modulation, 120 kV; contrast medium, 80 ml). Results: In all patients, we correctly visualized and evaluated main branches of the thoracic and abdominal aorta. No difference in density measurements was achieved between low tube voltage protocol (mean attenuation value of thoracic aorta, 304 HU; abdominal, 343 HU; renal arteries, 331 HU) and control group (mean attenuation value of thoracic aorta, 320 HU; abdominal, 339; renal arteries, 303 HU). Radiation dose exposure in low tube voltage protocol was significantly different between thoracic and abdominal low tube voltage studies (490 and 324 DLP, respectively) and the control group (thoracic DLP, 1032; abdomen, DLP 1078). Conclusion: Low-tube-voltage protocol may provide a diagnostic performance comparable with that of the standard protocol, decreasing radiation dose exposure and contrast material volume amount. Advances in knowledge: Low-tube-voltage-setting protocol combined with ultra-low contrast agent volume (30 ml), by using new multidetector-row CT scanners, represents a feasible diagnostic tool to significantly reduce the radiation dose delivered to patients and to preserve renal function

  14. Experimental study on the application of a compressed-sensing (CS) algorithm to dental cone-beam CT (CBCT) for accurate, low-dose image reconstruction

    NASA Astrophysics Data System (ADS)

    Oh, Jieun; Cho, Hyosung; Je, Uikyu; Lee, Minsik; Kim, Hyojeong; Hong, Daeki; Park, Yeonok; Lee, Seonhwa; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

    2013-03-01

    In practical applications of three-dimensional (3D) tomographic imaging, there are often challenges for image reconstruction from insufficient data. In computed tomography (CT); for example, image reconstruction from few views would enable fast scanning with reduced doses to the patient. In this study, we investigated and implemented an efficient reconstruction method based on a compressed-sensing (CS) algorithm, which exploits the sparseness of the gradient image with substantially high accuracy, for accurate, low-dose dental cone-beam CT (CBCT) reconstruction. We applied the algorithm to a commercially-available dental CBCT system (Expert7™, Vatech Co., Korea) and performed experimental works to demonstrate the algorithm for image reconstruction in insufficient sampling problems. We successfully reconstructed CBCT images from several undersampled data and evaluated the reconstruction quality in terms of the universal-quality index (UQI). Experimental demonstrations of the CS-based reconstruction algorithm appear to show that it can be applied to current dental CBCT systems for reducing imaging doses and improving the image quality.

  15. A low-dose, dual-phase cardiovascular CT protocol to assess left atrial appendage anatomy and exclude thrombus prior to left atrial intervention.

    PubMed

    Lazoura, Olga; Ismail, Tevfik F; Pavitt, Christopher; Lindsay, Alistair; Sriharan, Mona; Rubens, Michael; Padley, Simon; Duncan, Alison; Wong, Tom; Nicol, Edward

    2016-02-01

    Assessment of the left atrial appendage (LAA) for thrombus and anatomy is important prior to atrial fibrillation (AF) ablation and LAA exclusion. The use of cardiovascular CT (CCT) to detect LAA thrombus has been limited by the high incidence of pseudothrombus on single-pass studies. We evaluated the diagnostic accuracy of a two-phase protocol incorporating a limited low-dose delayed contrast-enhanced examination of the LAA, compared with a single-pass study for LAA morphological assessment, and transesophageal echocardiography (TEE) for the exclusion of thrombus. Consecutive patients (n = 122) undergoing left atrial interventions for AF were assessed. All had a two-phase CCT protocol (first-past scan plus a limited, 60-s delayed scan of the LAA) and TEE. Sensitivity, specificity, diagnostic accuracy, positive (PPV) and negative predictive values (NPV) were calculated for the detection of true thrombus on first-pass and delayed scans, using TEE as the gold standard. Overall, 20/122 (16.4 %) patients had filling defects on the first-pass study. All affected the full delineation of the LAA morphology; 17/20 (85 %) were confirmed as pseudo-filling defects. Three (15 %) were seen on late-pass and confirmed as true thrombi on TEE; a significant improvement in diagnostic performance relative to a single-pass scan (McNemar Chi-square 17, p < 0.001). The sensitivity, specificity, diagnostic accuracy, PPV and NPV was 100, 85.7, 86.1, 15.0 and 100 % respectively for first-pass scans, and 100 % for all parameters for the delayed scans. The median (range) additional radiation dose for the delayed scan was 0.4 (0.2-0.6) mSv. A low-dose delayed scan significantly improves the identification of true LAA anatomy and thrombus in patients undergoing LA intervention. PMID:26420491

  16. Ultra-low-dose dual-source CT coronary angiography with high pitch: diagnostic yield of a volumetric planning scan and effects on dose reduction and imaging strategy

    PubMed Central

    Hamm, B; Huppertz, A; Lembcke, A

    2015-01-01

    Objective: To evaluate the role of an ultra-low-dose dual-source CT coronary angiography (CTCA) scan with high pitch for delimiting the range of the subsequent standard CTCA scan. Methods: 30 patients with an indication for CTCA were prospectively examined using a two-scan dual-source CTCA protocol (2.0 × 64.0 × 0.6 mm; pitch, 3.4; rotation time of 280 ms; 100 kV): Scan 1 was acquired with one-fifth of the tube current suggested by the automatic exposure control software [CareDose 4D™ (Siemens Healthcare, Erlangen, Germany) using 100 kV and 370 mAs as a reference] with the scan length from the tracheal bifurcation to the diaphragmatic border. Scan 2 was acquired with standard tube current extending with reduced scan length based on Scan 1. Nine central coronary artery segments were analysed qualitatively on both scans. Results: Scan 2 (105.1 ± 10.1 mm) was significantly shorter than Scan 1 (127.0 ± 8.7 mm). Image quality scores were significantly better for Scan 2. However, in 5 of 6 (83%) patients with stenotic coronary artery disease, a stenosis was already detected in Scan 1 and in 13 of 24 (54%) patients with non-stenotic coronary arteries, a stenosis was already excluded by Scan 1. Using Scan 2 as reference, the positive- and negative-predictive value of Scan 1 was 83% (5 of 6 patients) and 100% (13 of 13 patients), respectively. Conclusion: An ultra-low-dose CTCA planning scan enables a reliable scan length reduction of the following standard CTCA scan and allows for correct diagnosis in a substantial proportion of patients. Advances in knowledge: Further dose reductions are possible owing to a change in the individual patient's imaging strategy as a prior ultra-low-dose CTCA scan may already rule out the presence of a stenosis or may lead to a direct transferal to an invasive catheter procedure. PMID:25710210

  17. Feasibility of low-dose CT with model-based iterative image reconstruction in follow-up of patients with testicular cancer

    PubMed Central

    Murphy, Kevin P.; Crush, Lee; O’Neill, Siobhan B.; Foody, James; Breen, Micheál; Brady, Adrian; Kelly, Paul J.; Power, Derek G.; Sweeney, Paul; Bye, Jackie; O’Connor, Owen J.; Maher, Michael M.; O’Regan, Kevin N.

    2016-01-01

    Purpose We examine the performance of pure model-based iterative reconstruction with reduced-dose CT in follow-up of patients with early-stage testicular cancer. Methods Sixteen patients (mean age 35.6 ± 7.4 years) with stage I or II testicular cancer underwent conventional dose (CD) and low-dose (LD) CT acquisition during CT surveillance. LD data was reconstructed with model-based iterative reconstruction (LD–MBIR). Datasets were objectively and subjectively analysed at 8 anatomical levels. Two blinded clinical reads were compared to gold-standard assessment for diagnostic accuracy. Results Mean radiation dose reduction of 67.1% was recorded. Mean dose measurements for LD–MBIR were: thorax – 66 ± 11 mGy cm (DLP), 1.0 ± 0.2 mSv (ED), 2.0 ± 0.4 mGy (SSDE); abdominopelvic – 128 ± 38 mGy cm (DLP), 1.9 ± 0.6 mSv (ED), 3.0 ± 0.6 mGy (SSDE). Objective noise and signal-to-noise ratio values were comparable between the CD and LD–MBIR images. LD–MBIR images were superior (p < 0.001) with regard to subjective noise, streak artefact, 2-plane contrast resolution, 2-plane spatial resolution and diagnostic acceptability. All patients were correctly categorised as positive, indeterminate or negative for metastatic disease by 2 readers on LD–MBIR and CD datasets. Conclusions MBIR facilitated a 67% reduction in radiation dose whilst producing images that were comparable or superior to conventional dose studies without loss of diagnostic utility. PMID:27069978

  18. Low-Dose (10%) Computed Tomography May Be Inferior to Standard-Dose CT in the Evaluation of Acute Renal Colic in the Emergency Room Setting

    PubMed Central

    Han, Esther; Atalla, Christopher S.; Santucci, Richard A.; O'Neil, Brian; Wynberg, Jason B.

    2016-01-01

    Abstract Introduction: Noncontrast CT is the standard of care to evaluate nephrolithiasis. We evaluated the performance of low-dose CT (LDCT) scan for evaluation of renal colic in the emergency room (ER). Materials and Methods: Patients visiting the ER with suspected nephrolithiasis received a standard-dose CT (SDCT) and an LDCT. Two urologists read the LDCTs and later they read SDCTs. Stone information was recorded on a diagram of the renal system. Findings on SDCTs and LDCTs were correlated through side-by-side comparison of the diagrams. Later, the two urologists adjudicated all nonconcordance between SDCTs and LDCTs in an unblinded manner. Results: Twenty-seven patients were included. SDCTs revealed 27 stones in 18 patients. Mean stone size was 3.81 mm. LDCTs revealed 27 stones in 18 patients with a mean stone size of 4.7 mm (p = 0.23). Overall sensitivity and specificity of LDCTs were 70% and 39%, respectively. There were eight false-positive and eight false-negative stones. All the false-positive stones on LDCTs were placed in the ureter, in which all of the corresponding SDCTs were visible calcifications outside the ureter. Of the eight false-negative stones on LDCTs, seven were visible calcifications on the SDCTs and the eighth stone was 1 mm and was not visible. Conclusion: LDCT may not perform well in the evaluation of suspected nephrolithiasis in the acute setting. LDCT scan accurately demonstrates calcifications; however, accurate placement of calcifications in or out of the urinary tract may be diminished due to impaired resolution of soft tissue structures. PMID:26728321

  19. Adaptive Statistical Iterative Reconstruction-Applied Ultra-Low-Dose CT with Radiography-Comparable Radiation Dose: Usefulness for Lung Nodule Detection

    PubMed Central

    Yoon, Hyun Jung; Hwang, Hye Sun; Moon, Jung Won; Lee, Kyung Soo

    2015-01-01

    Objective To assess the performance of adaptive statistical iterative reconstruction (ASIR)-applied ultra-low-dose CT (ULDCT) in detecting small lung nodules. Materials and Methods Thirty patients underwent both ULDCT and standard dose CT (SCT). After determining the reference standard nodules, five observers, blinded to the reference standard reading results, independently evaluated SCT and both subsets of ASIR- and filtered back projection (FBP)-driven ULDCT images. Data assessed by observers were compared statistically. Results Converted effective doses in SCT and ULDCT were 2.81 ± 0.92 and 0.17 ± 0.02 mSv, respectively. A total of 114 lung nodules were detected on SCT as a standard reference. There was no statistically significant difference in sensitivity between ASIR-driven ULDCT and SCT for three out of the five observers (p = 0.678, 0.735, < 0.01, 0.038, and < 0.868 for observers 1, 2, 3, 4, and 5, respectively). The sensitivity of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT in three out of the five observers (p < 0.01 for three observers, and p = 0.064 and 0.146 for two observers). In jackknife alternative free-response receiver operating characteristic analysis, the mean values of figure-of-merit (FOM) for FBP, ASIR-driven ULDCT, and SCT were 0.682, 0.772, and 0.821, respectively, and there were no significant differences in FOM values between ASIR-driven ULDCT and SCT (p = 0.11), but the FOM value of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT and SCT (p = 0.01 and 0.00). Conclusion Adaptive statistical iterative reconstruction-driven ULDCT delivering a radiation dose of only 0.17 mSv offers acceptable sensitivity in nodule detection compared with SCT and has better performance than FBP-driven ULDCT. PMID:26357505

  20. WE-G-18A-04: 3D Dictionary Learning Based Statistical Iterative Reconstruction for Low-Dose Cone Beam CT Imaging

    SciTech Connect

    Bai, T; Yan, H; Shi, F; Jia, X; Jiang, Steve B.; Lou, Y; Xu, Q; Mou, X

    2014-06-15

    Purpose: To develop a 3D dictionary learning based statistical reconstruction algorithm on graphic processing units (GPU), to improve the quality of low-dose cone beam CT (CBCT) imaging with high efficiency. Methods: A 3D dictionary containing 256 small volumes (atoms) of 3x3x3 voxels was trained from a high quality volume image. During reconstruction, we utilized a Cholesky decomposition based orthogonal matching pursuit algorithm to find a sparse representation on this dictionary basis of each patch in the reconstructed image, in order to regularize the image quality. To accelerate the time-consuming sparse coding in the 3D case, we implemented our algorithm in a parallel fashion by taking advantage of the tremendous computational power of GPU. Evaluations are performed based on a head-neck patient case. FDK reconstruction with full dataset of 364 projections is used as the reference. We compared the proposed 3D dictionary learning based method with a tight frame (TF) based one using a subset data of 121 projections. The image qualities under different resolutions in z-direction, with or without statistical weighting are also studied. Results: Compared to the TF-based CBCT reconstruction, our experiments indicated that 3D dictionary learning based CBCT reconstruction is able to recover finer structures, to remove more streaking artifacts, and is less susceptible to blocky artifacts. It is also observed that statistical reconstruction approach is sensitive to inconsistency between the forward and backward projection operations in parallel computing. Using high a spatial resolution along z direction helps improving the algorithm robustness. Conclusion: 3D dictionary learning based CBCT reconstruction algorithm is able to sense the structural information while suppressing noise, and hence to achieve high quality reconstruction. The GPU realization of the whole algorithm offers a significant efficiency enhancement, making this algorithm more feasible for potential

  1. Low-Dose Prospectively Electrocardiogram-Gated Axial Dual-Source CT Angiography in Patients with Pulsatile Bilateral Bidirectional Glenn Shunt: An Alternative Noninvasive Method for Postoperative Morphological Estimation

    PubMed Central

    Ji, Xiaopeng; Zhao, Bin; Cheng, Zhaoping; Si, Biao; Wang, Zhiheng; Duan, Yanhua; Nie, Pei; Li, Haiou; Yang, Shifeng; Jiao, Hui; Wang, Ximing

    2014-01-01

    Objective To explore the clinical value of low-dose prospectively electrocardiogram-gated axial dual-source CT angiography (low-dose PGA scanning, CTA) in patients with pulsatile bilateral bidirectional Glenn shunt (bBDG) as an alternative noninvasive method for postoperative morphological estimation. Methods Twenty patients with pulsatile bBDG (mean age 4.2±1.6 years) underwent both low-dose PGA scanning and conventional cardiac angiography (CCA) for the morphological changes. The morphological evaluation included the anatomy of superior vena cava (SVC) and pulmonary artery (PA), the anastomotic location, thrombosis, aorto-pulmonary collateral circulation, pulmonary arteriovenous malformations, etc. Objective and subjective image quality was assessed. Bland–Altman analysis and linear regression analyses were used to evaluate the correlation on measurements between CTA and CCA. Effective radiation dose of both modalities was calculated. Results The CT attenuation value of bilateral SVC and PA was higher than 300 HU. The average subjective image quality score was 4.05±0.69. The morphology of bilateral SVC and PA was displayed completely and intuitively by CTA images. There were 24 SVC above PA and 15 SVC beside PA. Thrombosis was found in 1 patient. Collateral vessels were detected in 13 patients. No pulmonary arteriovenous malformation was found in our study. A strong correlation (R2>0.8, P<0.001) was observed between the measurements on CTA images and on CCA images. Bland–Altman analysis demonstrated a systematic overestimation of the measurements by CTA (the mean value of bias>0).The mean effective dose of CTA and CCA was 0.50±0.17 mSv and 4.85±1.34 mSv respectively. Conclusion CT angiography with a low-dose PGA scanning is an accurate and reliable noninvasive examination in the assessment of morphological changes in patients with pulsatile bBDG. PMID:24736546

  2. Low-Dose Carcinogenicity Studies

    EPA Science Inventory

    One of the major deficiencies of cancer risk assessments is the lack of low-dose carcinogenicity data. Most assessments require extrapolation from high to low doses, which is subject to various uncertainties. Only 4 low-dose carcinogenicity studies and 5 low-dose biomarker/pre-n...

  3. Context-specific method for detection of soft-tissue lesions in non-cathartic low-dose dual-energy CT colonography

    NASA Astrophysics Data System (ADS)

    Näppi, Janne J.; Regge, Daniele; Yoshida, Hiroyuki

    2015-03-01

    In computed tomographic colonography (CTC), orally administered fecal-tagging agents can be used to indicate residual feces and fluid that could otherwise hide or imitate lesions on CTC images of the colon. Although the use of fecal tagging improves the detection accuracy of CTC, it can introduce image artifacts that may cause lesions that are covered by fecal tagging to have a different visual appearance than those not covered by fecal tagging. This can distort the values of image-based computational features, thereby reducing the accuracy of computer-aided detection (CADe). We developed a context-specific method that performs the detection of lesions separately on lumen regions covered by air and on those covered by fecal tagging, thereby facilitating the optimization of detection parameters separately for these regions and their detected lesion candidates to improve the detection accuracy of CADe. For pilot evaluation, the method was integrated into a dual-energy CADe (DE-CADe) scheme and evaluated by use of leave-one-patient-out evaluation on 66 clinical non-cathartic low dose dual-energy CTC (DE-CTC) cases that were acquired at a low effective radiation dose and reconstructed by use of iterative image reconstruction. There were 22 colonoscopy-confirmed lesions ≥6 mm in size in 21 patients. The DE-CADe scheme detected 96% of the lesions at a median of 6 FP detections per patient. These preliminary results indicate that the use of context-specific detection can yield high detection accuracy of CADe in non-cathartic low-dose DE-CTC examinations.

  4. Context-specific method for detection of soft-tissue lesions in non-cathartic low-dose dual-energy CT colonography

    PubMed Central

    Näppi, Janne J.; Regge, Daniele; Yoshida, Hiroyuki

    2015-01-01

    In computed tomographic colonography (CTC), orally administered fecal-tagging agents can be used to indicate residual feces and fluid that could otherwise hide or imitate lesions on CTC images of the colon. Although the use of fecal tagging improves the detection accuracy of CTC, it can introduce image artifacts that may cause lesions that are covered by fecal tagging to have a different visual appearance than those not covered by fecal tagging. This can distort the values of image-based computational features, thereby reducing the accuracy of computer-aided detection (CADe). We developed a context-specific method that performs the detection of lesions separately on lumen regions covered by air and on those covered by fecal tagging, thereby facilitating the optimization of detection parameters separately for these regions and their detected lesion candidates to improve the detection accuracy of CADe. For pilot evaluation, the method was integrated into a dual-energy CADe (DE-CADe) scheme and evaluated by use of leave-one-patient-out evaluation on 66 clinical non-cathartic low-dose dual-energy CTC (DE-CTC) cases that were acquired at a low effective radiation dose and reconstructed by use of iterative image reconstruction. There were 22 colonoscopy-confirmed lesions ≥6 mm in size in 21 patients. The DE-CADe scheme detected 96% of the lesions at a median of 6 FP detections per patient. These preliminary results indicate that the use of context-specific detection can yield high detection accuracy of CADe in non-cathartic low-dose DE-CTC examinations. PMID:25964710

  5. SU-C-207-03: Optimization of a Collimator-Based Sparse Sampling Technique for Low-Dose Cone-Beam CT

    SciTech Connect

    Lee, T; Cho, S; Kim, I; Han, B

    2015-06-15

    Purpose: In computed tomography (CT) imaging, radiation dose delivered to the patient is one of the major concerns. Sparse-view CT takes projections at sparser view angles and provides a viable option to reducing dose. However, a fast power switching of an X-ray tube, which is needed for the sparse-view sampling, can be challenging in many CT systems. We have earlier proposed a many-view under-sampling (MVUS) technique as an alternative to sparse-view CT. In this study, we investigated the effects of collimator parameters on the image quality and aimed to optimize the collimator design. Methods: We used a bench-top circular cone-beam CT system together with a CatPhan600 phantom, and took 1440 projections from a single rotation. The multi-slit collimator made of tungsten was mounted on the X-ray source for beam blocking. For image reconstruction, we used a total-variation minimization (TV) algorithm and modified the backprojection step so that only the measured data through the collimator slits are to be used in the computation. The number of slits and the reciprocation frequency have been varied and the effects of them on the image quality were investigated. We also analyzed the sampling efficiency: the sampling density and data incoherence in each case. We tested three sets of slits with their number of 6, 12 and 18, each at reciprocation frequencies of 10, 30, 50 and 70 Hz/ro. Results: Consistent results in the image quality have been produced with the sampling efficiency, and the optimum condition was found to be using 12 slits at 30 Hz/ro. As image quality indices, we used the CNR and the detectability. Conclusion: We conducted an experiment with a moving multi-slit collimator to realize a sparse-sampled cone-beam CT. Effects of collimator parameters on the image quality have been systematically investigated, and the optimum condition has been reached.

  6. Compressed-sensing (CS)-based 3D image reconstruction in cone-beam CT (CBCT) for low-dose, high-quality dental X-ray imaging

    NASA Astrophysics Data System (ADS)

    Lee, M. S.; Kim, H. J.; Cho, H. S.; Hong, D. K.; Je, U. K.; Oh, J. E.; Park, Y. O.; Lee, S. H.; Cho, H. M.; Choi, S. I.; Koo, Y. S.

    2013-09-01

    The most popular reconstruction algorithm for cone-beam computed tomography (CBCT) is based on the computationally-inexpensive filtered-backprojection (FBP) method. However, that method usually requires dense projections over the Nyquist samplings, which imposes severe restrictions on the imaging doses. Moreover, the algorithm tends to produce cone-beam artifacts as the cone angle is increased. Several variants of the FBP-based algorithm have been developed to overcome these difficulties, but problems with the cone-beam reconstruction still remain. In this study, we considered a compressed-sensing (CS)-based reconstruction algorithm for low-dose, high-quality dental CBCT images that exploited the sparsity of images with substantially high accuracy. We implemented the algorithm and performed systematic simulation works to investigate the imaging characteristics. CBCT images of high quality were successfully reconstructed by using the built-in CS-based algorithm, and the image qualities were evaluated quantitatively in terms of the universal-quality index (UQI) and the slice-profile quality index (SPQI).We expect the reconstruction algorithm developed in the work to be applicable to current dental CBCT systems, to reduce imaging doses, and to improve the image quality further.

  7. SU-E-I-39: Combining Conventional Tomographic Imaging Strategy and Interior Tomography for Low Dose Dual-Energy CT (DECT)

    SciTech Connect

    Xu, Q; Xing, L; Xiong, G; Elmore, K; Min, J

    2015-06-15

    Purpose: Dual-energy CT (DECT) affords quantitative information of tissue density and provides a new dimension for disease diagnosis and treatment planning. The technique, however, increases the imaging dose because of the doubled scans, and thus hinders its widespread clinical applications. The purpose of this work is to develop a novel hybrid DECT image acquisition and reconstruction strategy, in which one of the energies is dealt by interior tomography while the other one is obtained using conventional tomography approach. Methods: In the proposed hybrid imaging strategy, the projection data of one of the energies (e.g., high-energy) were acquired and processed in an interior scanning model, whereas the other energy in the conventional tomographic approach. It known that, if the ROI is piecewise constant or polynomial, the interior ROI can be reconstructed with TV or HOT minimization. Here we extend the TV based interior reconstruction method into dual-energy situation. The ROI images so obtained were overlaid in the context of conventional CT of the companion energy. A material based composition in ROI was used in the proposed reconstruction framework. Results: In the simulation experiment with a diagnostic DECT geometry and energies, we were able to derive the densities of soft-tissues and bones in the ROI with high fidelity. In the experimental CBCT study, both kV and MV data were collected using the on-board kV and MV imaging system. The MV data were truncated only across the ROI. Using the interior tomography reconstruction above, we were able to obtain the ROI images as that obtained using un-truncated MV data with known tissue densities. Conclusion: The proposed DECT imaging strategy provides an effective way to extract tissue density information in the ROI and in the context of anatomical images of CT imaging, with much reduced imaging dose.

  8. Evaluation of a Chest Circumference-Adapted Protocol for Low-Dose 128-Slice Coronary CT Angiography with Prospective Electrocardiogram Triggering

    PubMed Central

    Lu, Chenying; Wang, Zufei; Wang, Hailin; Hu, Xianghua; Chen, Chunmiao

    2015-01-01

    Objective To assess the effect of chest circumference-adapted scanning protocol on radiation exposure and image quality in patients undergoing prospective electrocardiogram (ECG)-triggered coronary CT angiography (CCTA). Materials and Methods One hundred-eighty-five consecutive patients, who had undergone prospective ECG triggering CCTA with a 128-slice CT, were included in the present study. Nipple-level chest circumference, body weight and height were measured before CT examinations. Patients were divided into four groups based on kV/ref·mAs = 100/200, 100/250, 120/200, and 120/250, when patient's chest circumference was ≤ 85.0 (n = 56), 85.0-90.0 (n = 53), 90.0-95.0 (n = 44), and > 95.0 (n = 32), respectively. Image quality per-segment was independently assessed by two experienced observers. Image noise and attenuation were also measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The effective radiation dose was calculated using CT dose volume index and the dose-length product. Results A significant correlation was observed between patients' chest circumference and body mass index (r = 0.762, p < 0.001). Chest circumference ranged from 74 to 105 cm, and the mean effective radiation dose was 1.9-3.8 mSv. Diagnostic image quality was obtained in 98.5% (2440/2478) of all evaluated coronary segments without any significant differences among the four groups (p = 0.650). No significant difference in image noise was observed among the four groups (p = 0.439), thus supporting the validity of the chest circumference-adapted scanning protocol. However, vessel attenuation, SNR and CNR were significantly higher in the 100 kV groups than in the 120 kV groups (p < 0.05). Conclusion A measure of chest circumference can be used to adapt tube voltage and current for individualized radiation dose control, with resultant similar image noise and sustained diagnostic image quality. PMID:25598671

  9. Low-dose coronary-CT angiography using step and shoot at any heart rate: comparison of image quality at systole for high heart rate and diastole for low heart rate with a 128-slice dual-source machine.

    PubMed

    Paul, Jean-François; Amato, Aude; Rohnean, Adela

    2013-03-01

    To compare image quality of coronary CT angiography in step-and-shoot mode at the diastolic phase at low heart rates (<70 bpm) and systolic phase at high heart rates (≥70 bpm). We prospectively included 96 consecutive patients then excluded 5 patients with arrhythmia. Coronary CT-angiography was performed using a dual-source 128-slice CT machine, at the diastolic phase in the 55 patients with heart rates <70 bpm (group D) and at the systolic phase in the 36 patients with heart rates ≥70 (group S). Image quality was scored on a 5 point-scale (1, not interpretable; 2, insufficient for diagnosis; 3, fair, sufficient for diagnosis; 4, good; 5, excellent). In addition, we compared the number of stair-step artifacts in the two groups. Mean image quality score was 4 (0.78) in group D and 4.1 (0.34) in group S (NS), with an unequal distribution (p = 0.01). Step artifacts were seen in 44 % of group D and 18 % of group S patients (p = 0.02). In 3 group D patients and no group S patients, the image score was <3 due to artifacts, requiring repeat CT-angiography. When performing dual-source 128-slice CT-angiography, step-and-shoot acquisition provides comparable mean image quality in systole, with less variability and fewer stair-step artifacts, compared to diastole. This method may be feasible at any heart rate in most patients in sinus rhythm, allowing low-dose prospective acquisition without beta-blocker premedication. PMID:22918571

  10. Preliminary performance of image quality for a low-dose C-arm CT system with a flat-panel detector

    NASA Astrophysics Data System (ADS)

    Kyung Cha, Bo; Seo, Chang-Woo; Yang, Keedong; Jeon, Seongchae; Huh, Young

    2015-06-01

    Digital flat panel imager (FPI)-based cone-beam computed tomography (CBCT) has been widely used in C-arm imaging for spine surgery and interventional procedures. The system provides real-time fluoroscopy with high spatial resolution and three-dimensional (3D) visualization of anatomical structure without the need for patient transportation in interventional suite. In this work, a prototype CBCT imaging platform with continuous single rotation about the gantry was developed by using a large-area flat-panel detector with amorphous Si-based thin film transistor matrix. The different 2D projection images were acquired during constant gantry velocity for reconstructed images at a tube voltage of 80-120 kVp, and different current (10-50 mA) conditions. Various scan protocols were applied to a chest phantom human by changing the number of projection images and scanning angles. The projections were then reconstructed into a volumetric data of sections by using a 3D reconstruction algorithm (e.g., filtered back projection). The preliminary quantitative X-ray performance of our CBCT system was investigated by using the American Association of Physicists in Medicine CT phantom in terms of spatial resolution, contrast resolution, and CT number linearity for mobile or fixed C-arm based CBCT application with limited rotational geometry. The novel results of the projection data with different scanning angles and angular increments in the orbital gantry platform were acquired and evaluated experimentally.

  11. SU-F-18C-13: Low-Dose X-Ray CT Reconstruction Using a Hybrid First-Order Method

    SciTech Connect

    Liu, L; Lin, W; Jin, M

    2014-06-15

    Purpose: To develop a novel reconstruction method for X-ray CT that can lead to accurate reconstruction at significantly reduced dose levels combining low X-ray incident intensity and few views of projection data. Methods: The noise nature of the projection data at low X-ray incident intensity was modeled and accounted by the weighted least-squares (WLS) criterion. The total variation (TV) penalty was used to mitigate artifacts caused by few views of data. The first order primal-dual (FOPD) algorithm was used to minimize TV in image domain, which avoided the difficulty of the non-smooth objective function. The TV penalized WLS reconstruction was achieved by alternated FOPD TV minimization and projection onto convex sets (POCS) for data fidelity constraints. The proposed FOPD-POCS method was evaluated using the FORBILD jaw phantom and the real cadaver head CT data. Results: The quantitative measures, root mean square error (RMSE) and contrast-to-noise ratio (CNR), demonstrate the superior denoising capability of WLS over LS-based TV iterative reconstruction. The improvement of RMSE (WLS vs. LS) is 15%∼21% and that of CNR is 17%∼72% when the incident counts per ray are ranged from 1×10{sup 5} to 1×10{sup 3}. In addition, the TV regularization can accurately reconstruct images from about 50 views of the jaw phantom. The FOPD-POCS reconstruction reveals more structural details and suffers fewer artifacts in both the phantom and real head images. The FOPD-POCS method also shows fast convergence at low X-ray incident intensity. Conclusion: The new hybrid FOPD-POCS method, based on TV penalized WLS, yields excellent image quality when the incident X-ray intensity is low and the projection views are limited. The reconstruction is computationally efficient since the FOPD minimization of TV is applied only in the image domain. The characteristics of FOPD-POCS can be exploited to significantly reduce radiation dose of X-ray CT without compromising accuracy for diagnosis

  12. Can use of adaptive statistical iterative reconstruction reduce radiation dose in unenhanced head CT? An analysis of qualitative and quantitative image quality

    PubMed Central

    Heggen, Kristin Livelten; Pedersen, Hans Kristian; Andersen, Hilde Kjernlie; Martinsen, Anne Catrine T

    2016-01-01

    Background Iterative reconstruction can reduce image noise and thereby facilitate dose reduction. Purpose To evaluate qualitative and quantitative image quality for full dose and dose reduced head computed tomography (CT) protocols reconstructed using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR). Material and Methods Fourteen patients undergoing follow-up head CT were included. All patients underwent full dose (FD) exam and subsequent 15% dose reduced (DR) exam, reconstructed using FBP and 30% ASIR. Qualitative image quality was assessed using visual grading characteristics. Quantitative image quality was assessed using ROI measurements in cerebrospinal fluid (CSF), white matter, peripheral and central gray matter. Additionally, quantitative image quality was measured in Catphan and vendor’s water phantom. Results There was no significant difference in qualitative image quality between FD FBP and DR ASIR. Comparing same scan FBP versus ASIR, a noise reduction of 28.6% in CSF and between −3.7 and 3.5% in brain parenchyma was observed. Comparing FD FBP versus DR ASIR, a noise reduction of 25.7% in CSF, and −7.5 and 6.3% in brain parenchyma was observed. Image contrast increased in ASIR reconstructions. Contrast-to-noise ratio was improved in DR ASIR compared to FD FBP. In phantoms, noise reduction was in the range of 3 to 28% with image content. Conclusion There was no significant difference in qualitative image quality between full dose FBP and dose reduced ASIR. CNR improved in DR ASIR compared to FD FBP mostly due to increased contrast, not reduced noise. Therefore, we recommend using caution if reducing dose and applying ASIR to maintain image quality. PMID:27583169

  13. Unenhanced Computed Tomography to Visualize Hollow Viscera and/or Mesenteric Injury After Blunt Abdominal Trauma

    PubMed Central

    Yang, Xu-Yang; Wei, Ming-Tian; Jin, Cheng-Wu; Wang, Meng; Wang, Zi-Qiang

    2016-01-01

    Abstract To identify and describe the major features of unenhanced computed tomography (CT) images of blunt hollow viscera and/or mesenteric injury (BHVI/MI) and to determine the value of unenhanced CT in the diagnosis of BHVI/MI. This retrospective study included 151 patients who underwent unenhanced CT before laparotomy for blunt abdominal trauma between January 2011 and December 2013. According to surgical observations, patients were classified as having BHVI/MI (n = 73) or not (n = 78). Sensitivity, specificity, P values, and likelihood ratios were calculated by comparing CT findings between the 2 groups. Six significant CT findings (P < 0.05) for BHVI/MI were identified and their sensitivity and specificity values determined, as follows: bowel wall thickening (39.7%, 96.2%), mesentery thickening (46.6%, 88.5%), mesenteric fat infiltration (12.3%, 98.7%), peritoneal fat infiltration (31.5%, 87.1%), parietal peritoneum thickening (30.1%, 85.9%), and intra- or retro-peritoneal air (34.2%, 96.2%). Unenhanced CT scan was useful as an initial assessment tool for BHVI/MI after blunt abdominal trauma. Six key features on CT were correlated with BHVI/MI. PMID:26945375

  14. Lung Cancer Screening with Low Dose CT

    PubMed Central

    Caroline, Chiles

    2014-01-01

    SUMMARY The announcement of the results of the NLST, showing a 20% reduction in lung-cancer specific mortality with LDCT screening in a high risk population, marked a turning point in lung cancer screening. This was the first time that a randomized controlled trial had shown a mortality reduction with an imaging modality aimed at early detection of lung cancer. Current guidelines endorse LDCT screening for smokers and former smokers ages 55 to 74, with at least a 30 pack year smoking history. Adherence to published algorithms for nodule follow-up is strongly encouraged. Future directions for screening research include risk stratification for selection of the screening population, and improvements in the diagnostic follow-up for indeterminate pulmonary nodules. As with screening for other malignancies, screening for lung cancer with LDCT has revealed that there are indolent lung cancers which may not be fatal. More research is necessary if we are to maximize the risk-benefit ratio in lung cancer screening. PMID:24267709

  15. TU-A-12A-12: Improved Airway Measurement Accuracy for Low Dose Quantitative CT (qCT) Using Statistical (ASIR), at Reduced DFOV, and High Resolution Kernels in a Phantom and Swine Model

    SciTech Connect

    Yadava, G; Imai, Y; Hsieh, J

    2014-06-15

    Purpose: Quantitative accuracy of Iodine Hounsfield Unit (HU) in conventional single-kVp scanning is susceptible to beam-hardening effect. Dual-energy CT has unique capabilities of quantification using monochromatic CT images, but this scanning mode requires the availability of the state-of-the-art CT scanner and, therefore, is limited in routine clinical practice. Purpose of this work was to develop a beam-hardening-correction (BHC) for single-kVp CT that can linearize Iodine projections at any nominal energy, apply this approach to study Iodine response with respect to keV, and compare with dual-energy based monochromatic images obtained from material-decomposition using 80kVp and 140kVp. Methods: Tissue characterization phantoms (Gammex Inc.), containing solid-Iodine inserts of different concentrations, were scanned using GE multi-slice CT scanner at 80, 100, 120, and 140 kVp. A model-based BHC algorithm was developed where Iodine was estimated using re-projection of image volume and corrected through an iterative process. In the correction, the re-projected Iodine was linearized using a polynomial mapping between monochromatic path-lengths at various nominal energies (40 to 140 keV) and physically modeled polychromatic path-lengths. The beam-hardening-corrected 80kVp and 140kVp images (linearized approximately at effective energy of the beam) were used for dual-energy material-decomposition in Water-Iodine basis-pair followed by generation of monochromatic images. Characterization of Iodine HU and noise in the images obtained from singlekVp with BHC at various nominal keV, and corresponding dual-energy monochromatic images, was carried out. Results: Iodine HU vs. keV response from single-kVp with BHC and dual-energy monochromatic images were found to be very similar, indicating that single-kVp data may be used to create material specific monochromatic equivalent using modelbased projection linearization. Conclusion: This approach may enable quantification of

  16. Towards the clinical implementation of iterative low-dose cone-beam CT reconstruction in image-guided radiation therapy: Cone/ring artifact correction and multiple GPU implementation

    SciTech Connect

    Yan, Hao E-mail: xun.jia@utsouthwestern.edu; Shi, Feng; Jiang, Steve B.; Jia, Xun E-mail: xun.jia@utsouthwestern.edu; Wang, Xiaoyu; Cervino, Laura; Bai, Ti; Folkerts, Michael

    2014-11-01

    , an overall 3.1 × speedup factor has been achieved with four GPU cards compared to a single GPU-based reconstruction. The total computation time is ∼30 s for typical clinical cases. Conclusions: The authors have developed a low-dose CBCT IR system for IGRT. By incorporating data consistency-based weighting factors in the IR model, cone/ring artifacts can be mitigated. A boost in computational efficiency is achieved by multi-GPU implementation.

  17. WE-G-18A-01: JUNIOR INVESTIGATOR WINNER - Low-Dose C-Arm Cone-Beam CT with Model-Based Image Reconstruction for High-Quality Guidance of Neurosurgical Intervention

    SciTech Connect

    Wang, A; Stayman, J; Otake, Y; Gallia, G; Siewerdsen, J

    2014-06-15

    improvement in image quality, dose reduction, and reconstruction time of ∼4 min will enable practical deployment of low-dose C-arm CBCT within the operating room. AAPM Research Seed Funding (2013-2014); NIH Fellowship F32EB017571; Siemens Healthcare (XP Division)

  18. Towards the clinical implementation of iterative low-dose cone-beam CT reconstruction in image-guided radiation therapy: Cone/ring artifact correction and multiple GPU implementation

    PubMed Central

    Yan, Hao; Wang, Xiaoyu; Shi, Feng; Bai, Ti; Folkerts, Michael; Cervino, Laura; Jiang, Steve B.; Jia, Xun

    2014-01-01

    , an overall 3.1 × speedup factor has been achieved with four GPU cards compared to a single GPU-based reconstruction. The total computation time is ∼30 s for typical clinical cases. Conclusions: The authors have developed a low-dose CBCT IR system for IGRT. By incorporating data consistency-based weighting factors in the IR model, cone/ring artifacts can be mitigated. A boost in computational efficiency is achieved by multi-GPU implementation. PMID:25370645

  19. Advances in CT imaging for urolithiasis

    PubMed Central

    Andrabi, Yasir; Patino, Manuel; Das, Chandan J.; Eisner, Brian; Sahani, Dushyant V.; Kambadakone, Avinash

    2015-01-01

    Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice. PMID:26166961

  20. Advances in CT imaging for urolithiasis.

    PubMed

    Andrabi, Yasir; Patino, Manuel; Das, Chandan J; Eisner, Brian; Sahani, Dushyant V; Kambadakone, Avinash

    2015-01-01

    Urolithiasis is a common disease with increasing prevalence worldwide and a lifetime-estimated recurrence risk of over 50%. Imaging plays a critical role in the initial diagnosis, follow-up and urological management of urinary tract stone disease. Unenhanced helical computed tomography (CT) is highly sensitive (>95%) and specific (>96%) in the diagnosis of urolithiasis and is the imaging investigation of choice for the initial assessment of patients with suspected urolithiasis. The emergence of multi-detector CT (MDCT) and technological innovations in CT such as dual-energy CT (DECT) has widened the scope of MDCT in the stone disease management from initial diagnosis to encompass treatment planning and monitoring of treatment success. DECT has been shown to enhance pre-treatment characterization of stone composition in comparison with conventional MDCT and is being increasingly used. Although CT-related radiation dose exposure remains a valid concern, the use of low-dose MDCT protocols and integration of newer iterative reconstruction algorithms into routine CT practice has resulted in a substantial decrease in ionizing radiation exposure. In this review article, our intent is to discuss the role of MDCT in the diagnosis and post-treatment evaluation of urolithiasis and review the impact of emerging CT technologies such as dual energy in clinical practice. PMID:26166961

  1. Initial staging of Hodgkin's disease: role of contrast-enhanced 18F FDG PET/CT.

    PubMed

    Chiaravalloti, Agostino; Danieli, Roberta; Caracciolo, Cristiana Ragano; Travascio, Laura; Cantonetti, Maria; Gallamini, Andrea; Guazzaroni, Manlio; Orlacchio, Antonio; Simonetti, Giovanni; Schillaci, Orazio

    2014-08-01

    The objective of this study was to compare the diagnostic accuracy of positron emission tomography/low-dose computed tomography (PET/ldCT) versus the same technique implemented by contrast-enhanced computed tomography (ceCT) in staging Hodgkin's disease (HD).Forty patients (18 men and 22 women, mean age 30 ± 9.6) with biopsy-proven HD underwent a PET/ldCT study for initial staging including an unenhanced low-dose computed tomography for attenuation correction with positron emission tomography acquisition and a ceCT, performed at the end of the PET/ldCT scan, in the same exam session. A detailed datasheet was generated for illness locations for separate imaging modality comparison and then merged in order to compare the separate imaging method results (PET/ldCT and ceCT) versus merged results positron emission tomography/contrast-enhanced computed tomography (PET/ceCT). The nodal and extranodal lesions detected by each technique were then compared with follow-up data that served as the reference standard.No significant differences were found at staging between PET/ldCT and PET/ceCT in our series. One hundred and eighty four stations of nodal involvement have been found with no differences in both modalities. Extranodal involvement was identified in 26 sites by PET/ldCT and in 28 by PET/ceCT. We did not find significant differences concerning the stage (Ann Arbor).Our study shows a good concordance and conjunction between PET/ldCT and ceCT in both nodal and extranodal sites in the initial staging of HD, suggesting that PET/ldCT could suffice in most of these patients. PMID:25121354

  2. Low Dose Risk, Decisions, and Risk Communication

    SciTech Connect

    Flynn, James

    2002-09-14

    The overall research objective was to establish new levels of information about how people, groups, and communities respond to low dose radiation exposure. This is basic research into the social psychology of individual, group, and community responses to radiation exposures. The results of this research are directed to improving risk communication and public participation in management of environmental problems resulting from low dose radiation.

  3. Low Dose Effects in Psychopharmacology: Ontogenetic Considerations

    PubMed Central

    Spear, Linda Patia; Varlinskaya, Elena I.

    2005-01-01

    Low doses of psychoactive drugs often elicit a behavioral profile opposite to that observed following administration of more substantial doses. Our laboratory has observed that these effects are often age-specific in rats. For instance, whereas moderate to high doses of the dopamine agonist apomorphine increase locomotion, suppressed locomotor activity is seen following low dose exposure, with this low dose effect not emerging consistently until adolescence. A somewhat earlier emergence of a low dose “paradoxical” effect is seen with the 5HT1a receptor agonist, 8-OH-DPAT, with late preweanling, but not neonatal, rats showing increases in ingestive behavior at low doses but suppression at higher doses. In contrast to these ontogenetic increases in expression of low dose drug effects, low dose facilitation of social behavior is seen following ethanol only in adolescent rats and not their mature counterparts, although suppression of social interactions at higher doses is seen at both ages. This hormesis-like low dose stimulation appears related in part to overcompensation, with brief social suppression preceding the subsequent stimulation response, and also bears a number of ontogenetic similarities to acute tolerance, a well characterized, rapidly emerging adaptation to ethanol. Implications of these and other ontogenetic findings for studies of hormesis are discussed. PMID:19330157

  4. Radiotherapy treatment planning with contrast-enhanced computed tomography: feasibility of dual-energy virtual unenhanced imaging for improved dose calculations

    PubMed Central

    2014-01-01

    Background In radiotherapy treatment planning, intravenous administration of an iodine-based contrast agent during computed tomography (CT) improves the accuracy of delineating target volumes. However, increased tissue attenuation resulting from the high atomic number of iodine may result in erroneous dose calculations because the contrast agent is absent during the actual procedure. The purpose of this proof-of-concept study was to present a novel framework to improve the accuracy of dose calculations using dual-energy virtual unenhanced CT in the presence of an iodine-based contrast agent. Methods Simple phantom experiments were designed to assess the feasibility of the proposed concept. By utilizing a “second-generation” dual-source CT scanner equipped with a tin filter for improved spectral separation, four CT datasets were obtained using both a water phantom and an iodine phantom: “true unenhanced” images with attenuation values of 2 ± 11 Hounsfield Units (HU), “enhanced” images with attenuation values of 274 ± 23 HU, and two series of “virtual unenhanced” images synthesized from dual-energy scans of the iodine phantom, each with a different combination of tube voltages. Two series of virtual unenhanced images demonstrated attenuation values of 12 ± 29 HU (with 80 kVp/140 kVp) and 34 ± 10 HU (with 100 kVp/140 kVp) after removing the iodine component from the contrast-enhanced images. Dose distributions of the single photon beams calculated from the enhanced images and two series of virtual unenhanced images were compared to those from true unenhanced images as a reference. Results The dose distributions obtained from both series of virtual unenhanced images were almost equivalent to that from the true unenhanced images, whereas the dose distribution obtained from the enhanced images indicated increased beam attenuation caused by the high attenuation characteristics of iodine. Compared to the reference dose distribution from

  5. Equivocal Pediatric Appendicitis: Unenhanced MR Imaging Protocol for Nonsedated Children-A Clinical Effectiveness Study.

    PubMed

    Dillman, Jonathan R; Gadepalli, Samir; Sroufe, Nicole S; Davenport, Matthew S; Smith, Ethan A; Chong, Suzanne T; Mazza, Michael B; Strouse, Peter J

    2016-04-01

    Purpose To determine retrospectively the clinical effectiveness of an unenhanced magnetic resonance (MR) imaging protocol for evaluation of equivocal appendicitis in children. Materials and Methods Institutional review board approval was obtained. Pediatric patients (≤18 years old) underwent unenhanced MR imaging and contrast material-enhanced computed tomography (CT) of the appendix between December 2013 and November 2014 and December 2012 and November 2013, respectively, within 24 hours after an abdominal ultrasonographic examination with results equivocal for appendicitis. Pertinent MR imaging and CT reports were reviewed for visibility of the appendix, presence of appendicitis and appendiceal perforation, and establishment of an alternative diagnosis. Surgical reports, pathologic reports, and 30-day follow-up medical records were used as reference standards. Diagnostic performance with MR imaging and CT was calculated with 95% confidence intervals (CIs) for diagnosis of appendicitis and appendiceal perforation. The Fisher exact test was used to compare proportions; the Student t test was used to compare means. Results Diagnostic performance with MR imaging was comparable to that with CT for equivocal pediatric appendicitis. For MR imaging (n = 103), sensitivity was 94.4% (95% CI: 72.7%, 99.9%) and specificity was 100% (95% CI: 95.8%, 100%); for CT [n = 58], sensitivity was 100% (95% CI: 71.5%, 100%), specificity was 97.9% (95% CI: 88.7%, 100%). Diagnostic performance with MR imaging and CT also was comparable for detection of appendiceal perforation, with MR imaging (n = 103) sensitivity of 90.0% (95% CI: 55.5%, 99.8%) and specificity of 85.7% (95% CI: 42.1%, 99.6%) and CT (n = 58) sensitivity of 75.0% (95% CI: 19.4%, 99.4%) and specificity of 85.7% (95% CI: 42.1%, 99.6%). The proportion of examinations with identifiable alternative diagnoses was similar at MR imaging to that at CT (19 of 103 [18.4%] vs eight of 58 [13.8%], respectively; P = .52). The

  6. Radiation Leukemogenesis at Low Dose Rates

    SciTech Connect

    Weil, Michael; Ullrich, Robert

    2013-09-25

    The major goals of this program were to study the efficacy of low dose rate radiation exposures for the induction of acute myeloid leukemia (AML) and to characterize the leukemias that are caused by radiation exposures at low dose rate. An irradiator facility was designed and constructed that allows large numbers of mice to be irradiated at low dose rates for protracted periods (up to their life span). To the best of our knowledge this facility is unique in the US and it was subsequently used to study radioprotectors being developed for radiological defense (PLoS One. 7(3), e33044, 2012) and is currently being used to study the role of genetic background in susceptibility to radiation-induced lung cancer. One result of the irradiation was expected; low dose rate exposures are ineffective in inducing AML. However, another result was completely unexpected; the irradiated mice had a very high incidence of hepatocellular carcinoma (HCC), approximately 50%. It was unexpected because acute exposures are ineffective in increasing HCC incidence above background. This is a potential important finding for setting exposure limits because it supports the concept of an 'inverse dose rate effect' for some tumor types. That is, for the development of some tumor types low dose rate exposures carry greater risks than acute exposures.

  7. Low Dose Effects: Benefit or Harm?

    PubMed

    Woloschak, Gayle E

    2016-03-01

    This forum article discusses issues related to the effects of low dose radiation, an area that is under intense study but difficult to assess. Experiments with large-scale animal studies are included in this paper; these studies point to the need for international consortia to examine and balance the results of these large-scale studies and databases. PMID:26808889

  8. Mammography-oncogenecity at low doses.

    PubMed

    Heyes, G J; Mill, A J; Charles, M W

    2009-06-01

    Controversy exists regarding the biological effectiveness of low energy x-rays used for mammography breast screening. Recent radiobiology studies have provided compelling evidence that these low energy x-rays may be 4.42 +/- 2.02 times more effective in causing mutational damage than higher energy x-rays. These data include a study involving in vitro irradiation of a human cell line using a mammography x-ray source and a high energy source which matches the spectrum of radiation observed in survivors from the Hiroshima atomic bomb. Current radiation risk estimates rely heavily on data from the atomic bomb survivors, and a direct comparison between the diagnostic energies used in the UK breast screening programme and those used for risk estimates can now be made. Evidence highlighting the increase in relative biological effectiveness (RBE) of mammography x-rays to a range of x-ray energies implies that the risks of radiation-induced breast cancers for mammography x-rays are potentially underestimated by a factor of four. A pooled analysis of three measurements gives a maximal RBE (for malignant transformation of human cells in vitro) of 4.02 +/- 0.72 for 29 kVp (peak accelerating voltage) x-rays compared to high energy electrons and higher energy x-rays. For the majority of women in the UK NHS breast screening programme, it is shown that the benefit safely exceeds the risk of possible cancer induction even when this higher biological effectiveness factor is applied. The risk/benefit analysis, however, implies the need for caution for women screened under the age of 50, and particularly for those with a family history (and therefore a likely genetic susceptibility) of breast cancer. In vitro radiobiological data are generally acquired at high doses, and there are different extrapolation mechanisms to the low doses seen clinically. Recent low dose in vitro data have indicated a potential suppressive effect at very low dose rates and doses. Whilst mammography is a low

  9. Epigenomic Adaptation to Low Dose Radiation

    SciTech Connect

    Gould, Michael N.

    2015-06-30

    The overall hypothesis of this grant application is that the adaptive responses elicited by low dose ionizing radiation (LDIR) result in part from heritable DNA methylation changes in the epigenome. In the final budget period at the University of Wisconsin-Madison, we will specifically address this hypothesis by determining if the epigenetically labile, differentially methylated regions (DMRs) that regulate parental-specific expression of imprinted genes are deregulated in agouti mice by low dose radiation exposure during gestation. This information is particularly important to ascertain given the 1) increased human exposure to medical sources of radiation; 2) increased number of people predicted to live and work in space; and 3) enhanced citizen concern about radiation exposure from nuclear power plant accidents and terrorist ‘dirty bombs.’

  10. Validation of a Low Dose Simulation Technique for Computed Tomography Images

    PubMed Central

    Muenzel, Daniela; Koehler, Thomas; Brown, Kevin; Žabić, Stanislav; Fingerle, Alexander A.; Waldt, Simone; Bendik, Edgar; Zahel, Tina; Schneider, Armin; Dobritz, Martin; Rummeny, Ernst J.; Noël, Peter B.

    2014-01-01

    Purpose Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan. Materials and Methods Original CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV) of a swine were acquired (approved by the regional governmental commission for animal protection). Simulations of CT acquisition with a lower dose (simulated 10–80 mAs) were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images. Results Image characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was −1.2% (range −9% to 3.2%) and −0.2% (range −8.2% to 3.2%), respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9–10.2 HU (noise) and 1.9–13.4 HU (CT values), without significant differences (p>0.05). Subjective observer evaluation of image appearance showed no visually detectable difference. Conclusion Simulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques. PMID:25247422

  11. The importance of lung cancer screening with low-dose computed tomography for Medicare beneficiaries.

    PubMed

    Wood, Douglas E

    2014-12-01

    The National Lung Screening Trial has provided convincing evidence of a substantial mortality benefit of lung cancer screening with low-dose computed tomography (CT) for current and former smokers at high risk. The United States Preventive Services Task Force has recommended screening, triggering coverage of low-dose CT by private health insurers under provisions of the Affordable Care Act. The Centers for Medicare & Medicaid Services (CMS) are currently evaluating coverage of lung cancer screening for Medicare beneficiaries. Since 70% of lung cancer occurs in patients 65 years or older, CMS should cover low-dose CT, thus avoiding the situation of at-risk patients being screened up to age 64 through private insurers and then abruptly ceasing screening at exactly the ages when their risk for developing lung cancer is increasing. Legitimate concerns include false-positive findings that lead to further testing and invasive procedures, overdiagnosis (detection of clinically unimportant cancers), the morbidity and mortality of surgery, and the overall costs of follow-up tests and procedures. These concerns can be mitigated by clear criteria for screening high-risk patients, disciplined management of abnormalities based on algorithms, and high-quality multidisciplinary care. Lung cancer screening with low-dose CT can lead to early diagnosis and cure for thousands of patients each year. Professional societies can help CMS responsibly implement a program that is patient-centered and minimizes unintended harms and costs. PMID:25317992

  12. [Low dose naltrexone for treatment of pain].

    PubMed

    Plesner, Karin Bruun; Vægter, Henrik Bjarke; Handberg, Gitte

    2015-10-01

    Recent years have seen an increasing interest in the use of low dose naltrexone (LDN) for off-label treatment of pain in diseases as fibromyalgia, multiple sclerosis and morbus Crohn. The evidence is poor, with only few randomized double-blind placebo-controlled studies. The studies currently available are reviewed in this paper. LDN could be a potentially useful drug in the future for the treatment of pain in fibromyalgia, but more studies are needed to verify that it is superior to placebo, and currently it cannot be recommended as first-line therapy. PMID:26509454

  13. Low Dose MDCT with Tube Current Modulation: Role in Detection of Urolithiasis and Patient Effective Dose Reduction

    PubMed Central

    Kakkar, Chandan; Sripathi, Smiti; Parakh, Anushri; Shrivastav, Rajendra

    2016-01-01

    Introduction Urolithiasis is one of the major, recurring problem in young individuals and CT being the commonest diagnostic modality used. In order to reduce the radiation dose to the patient who are young and as stone formation is a recurring process; one of the simplest way would be, low dose CT along with tube current modulation. Aim Aim of this study was to compare the sensitivity and specificity of low dose (70mAs) with standard dose (250mAs) protocol in detecting urolithiasis and to define the tube current and mean effective patient dose by these protocols. Materials and Methods A prospective study was conducted in 200 patients over a period of 2 years with acute flank pain presentation. CT was performed in 100 cases with standard dose and another 100 with low dose protocol using tube current modulation. Sensitivity and specificity for calculus detection, percentage reduction of dose and tube current with low dose protocol was calculated. Results Urolithiasis was detected in 138 patients, 67 were examined by high dose and 71 were by low dose protocol. Sensitivity and Specificity of low dose protocol was 97.1% and 96.4% with similar results found in high BMI patients. Tube current modulation resulted in reduction of effective tube current by 12.17%. The mean effective patient dose for standard dose was 10.33 mSv whereas 2.92 mSv for low dose with 51.13–53.8% reduction in low dose protocol. Conclusion The study has reinforced that low-dose CT with tube current modulation is appropriate for diagnosis of urolithiasis with significant reduction in tube current and patient effective dose. PMID:27437322

  14. [Complications of low-dose amiodarone].

    PubMed

    Feigl, D; Gilad, R; Katz, E

    1991-11-15

    Complications of low-dose amiodarone in 83 patients, in whom the drug was effective and who were followed for 1-13 years, are presented. Hypothyroidism was diagnosed in 11 (in 8 by the finding of elevated TSH). In 2 of the 3 in whom clinical signs of hypothyroidism were evident, amiodarone was continued, but thyroxine was also given. In 5 others thyrotoxicosis ensued. Propylthiouracil (PTU) was given and amiodarone was discontinued. PTU was then stopped within 4-8 months, without recurrence of the hyperthyroidism. In 1 patient pneumonitis resolved spontaneously a few weeks after stopping amiodarone. Because of gastrointestinal distress amiodarone was stopped in 1 patient. In none were liver enzymes elevated, nor was the nervous system affected clinically. Photosensitivity in 6 patients and skin discoloration in 2 did not necessitate discontinuation of the drug. Blurred vision was reported by 4, but its connection with amiodarone was not proven. There was sinus bradycardia in 2. There was no arrhythmic effect of amiodarone seen on ECG nor on Holter monitoring, nor was there any mortality. We conclude that amiodarone in low doses causes many complications, most of them mild and transient. However, in only a few cases is discontinuation of the drug indicated. PMID:1752553

  15. Low-dose radiation exposure and carcinogenesis.

    PubMed

    Suzuki, Keiji; Yamashita, Shunichi

    2012-07-01

    Absorption of energy from ionizing radiation by the genetic material in the cell leads to damage to DNA, which in turn leads to cell death, chromosome aberrations and gene mutations. While early or deterministic effects result from organ and tissue damage caused by cell killing, latter two are considered to be involved in the initial events that lead to the development of cancer. Epidemiological studies have demonstrated the dose-response relationships for cancer induction and quantitative evaluations of cancer risk following exposure to moderate to high doses of low-linear energy transfer radiation. A linear, no-threshold model has been applied to assessment of the risks resulting from exposure to moderate and high doses of ionizing radiation; however, a statistically significant increase has hardly been described for radiation doses below 100 mSv. This review summarizes our current knowledge of the physical and biological features of low-dose radiation and discusses the possibilities of induction of cancer by low-dose radiation. PMID:22641644

  16. An automated system for lung nodule detection in low-dose computed tomography

    NASA Astrophysics Data System (ADS)

    Gori, I.; Fantacci, M. E.; Preite Martinez, A.; Retico, A.

    2007-03-01

    A computer-aided detection (CAD) system for the identification of pulmonary nodules in low-dose multi-detector helical Computed Tomography (CT) images was developed in the framework of the MAGIC-5 Italian project. One of the main goals of this project is to build a distributed database of lung CT scans in order to enable automated image analysis through a data and cpu GRID infrastructure. The basic modules of our lung-CAD system, a dot-enhancement filter for nodule candidate selection and a neural classifier for false-positive finding reduction, are described. The system was designed and tested for both internal and sub-pleural nodules. The results obtained on the collected database of low-dose thin-slice CT scans are shown in terms of free response receiver operating characteristic (FROC) curves and discussed.

  17. Culmination of Low-Dose Pesticide Effects

    PubMed Central

    2013-01-01

    Pesticides applied in agriculture can affect the structure and function of nontarget populations at lower doses and for longer timespans than predicted by the current risk assessment frameworks. We identified a mechanism for this observation. The populations of an aquatic invertebrate (Culex pipiens) exposed over several generations to repeated pulses of low concentrations of the neonicotinoid insecticide (thiacloprid) continuously declined and did not recover in the presence of a less sensitive competing species (Daphnia magna). By contrast, in the absence of a competitor, insecticide effects on the more sensitive species were only observed at concentrations 1 order of magnitude higher, and the species recovered more rapidly after a contamination event. The underlying processes are experimentally identified and reconstructed using a simulation model. We conclude that repeated toxicant pulse of populations that are challenged with interspecific competition may result in a multigenerational culmination of low-dose effects. PMID:23859631

  18. Low dose neutron late effects: Cataractogenesis

    SciTech Connect

    Worgul, B.V.

    1991-12-01

    The work is formulated to resolve the uncertainty regarding the relative biological effectiveness (RBE) of low dose neutron radiation. The study exploits the fact that cataractogenesis is sensitive to the inverse dose-rate effect as has been observed with heavy ions and was an endpoint considered in the follow-up of the A-bomb survivors. The neutron radiations were initiated at the Radiological Research Accelerator facility (RARAF) of the Nevis Laboratory of Columbia University. Four week old ({plus minus} 1 day) rats were divided into eight dose groups each receiving single or fractionated total doses of 0.2, 1.0, 5.0 and 25.0 cGy of monoenergetic 435 KeV neutrons. Special restraining jigs insured that the eye, at the midpoint of the lens, received the appropriate energy and dose with a relative error of {plus minus}5%. The fractionation regimen consisted of four exposures, each administered at three hour ({plus minus}) intervals. The neutron irradiated groups are being compared to rats irradiated with 250kVp X-rays in doses ranging from 0.5 to 7 Gy. The animals are being examined on a biweekly basis utilizing conventional slit-lamp biomicroscopy and the Scheimpflug Slit Lamp Imaging System (Zeiss). The follows-ups, entering their second year, will continue throughout the life-span of the animals. This is essential inasmuch as given the extremely low doses which are being utilized clinically detectable opacities were not anticipated until a significant fraction of the life span has lapsed. Current data support this contention. At this juncture cataracts in the irradiated groups are beginning to exceed control levels.

  19. Low-Dose Radiotherapy in Indolent Lymphoma

    SciTech Connect

    Rossier, Christine; Schick, Ulrike; Miralbell, Raymond; Mirimanoff, Rene O.; Weber, Damien C.; Ozsahin, Mahmut

    2011-11-01

    Purpose: To assess the response rate, duration of response, and overall survival after low-dose involved-field radiotherapy in patients with recurrent low-grade lymphoma or chronic lymphocytic leukemia (CLL). Methods and Materials: Forty-three (24 women, 19 men) consecutive patients with indolent lymphoma or CLL were treated with a total dose of 4 Gy (2 x 2 Gy) using 6- 18-MV photons. The median age was 73 years (range, 39-88). Radiotherapy was given either after (n = 32; 75%) or before (n = 11; 25%) chemotherapy. The median time from diagnosis was 48 months (range, 1-249). The median follow-up period was 20 months (range, 1-56). Results: The overall response rate was 90%. Twelve patients (28%) had a complete response, 15 (35%) had a partial response, 11 (26%) had stable disease, and 5 (11%) had progressive disease. The median overall survival for patients with a positive response (complete response/partial response/stable disease) was 41 months; for patients with progressive disease it was 6 months (p = 0.001). The median time to in-field progression was 21 months (range, 0-24), and the median time to out-field progression was 8 months (range, 0-40). The 3-year in-field control was 92% in patients with complete response (median was not reached). The median time to in-field progression was 9 months (range, 0.5-24) in patients with partial response and 6 months (range, 0.6-6) in those with stable disease (p < 0.05). Younger age, positive response to radiotherapy, and no previous chemotherapy were the best factors influencing the outcome. Conclusions: Low-dose involved-field radiotherapy is an effective treatment in the management of patients with recurrent low-grade lymphoma or CLL.

  20. Enhanced Low Dose Rate Sensitivity at Ultra-Low Dose Rates

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; Pease, Ronald; Forney, James; Carts, Martin; Phan, Anthony; Cox, Stephen; Kruckmeyer, Kriby; Burns, Sam; Albarian, Rafi; Holcombe, Bruce; Little, Bradley; Salzman, James; Chaumont, Geraldine; Duperray, Herve; Ouellet, Al; Buchner, Stephen; LaBel, Kenneth

    2011-01-01

    We have presented results of ultra-low dose rate irradiations (< or = 10 mrad(Si)/s) for a variety of radiation hardened and commercial linear bipolar devices. We observed low dose rate enhancement factors exceeding 1.5 in several parts. The worst case of dose rate enhancement resulted in functional failures, which occurred after 10 and 60 krad(Si), for devices irradiated at 0.5 and 10 mrad(Si)/s, respectively. Devices fabricated with radiation hardened processes and designs also displayed dose rate enhancement at below 10 mrad(Si)/s. Furthermore, the data indicated that these devices have not reached the damage saturation point. Therefore the degradation will likely continue to increase with increasing total dose, and the low dose rate enhancement will further magnify. The cases presented here, in addition to previous examples, illustrate the significance and pervasiveness of low dose rate enhancement at dose rates lower than 10 mrad(Si). These results present further challenges for radiation hardness assurance of bipolar linear circuits, and raise the question of whether the current standard test dose rate is conservative enough to bound degradations due to ELDRS.

  1. LINKING MOLECULAR EVENT TO CELLULAR RESPONSES AT LOW DOSE EXPOSURES

    EPA Science Inventory

    Defining low dose radiation cancer risks is limited by our ability to measure and directly correlate relevant cellular and molecular responses occurring at low dose and dose rate with tumor formation. This deficiency has led to conservative risk assessments based on low dose ext...

  2. Low-dose computed tomography image restoration using previous normal-dose scan

    SciTech Connect

    Ma, Jianhua; Huang, Jing; Feng, Qianjin; Zhang, Hua; Lu, Hongbing; Liang, Zhengrong; Chen, Wufan

    2011-10-15

    Purpose: In current computed tomography (CT) examinations, the associated x-ray radiation dose is of a significant concern to patients and operators. A simple and cost-effective means to perform the examinations is to lower the milliampere-seconds (mAs) or kVp parameter (or delivering less x-ray energy to the body) as low as reasonably achievable in data acquisition. However, lowering the mAs parameter will unavoidably increase data noise and the noise would propagate into the CT image if no adequate noise control is applied during image reconstruction. Since a normal-dose high diagnostic CT image scanned previously may be available in some clinical applications, such as CT perfusion imaging and CT angiography (CTA), this paper presents an innovative way to utilize the normal-dose scan as a priori information to induce signal restoration of the current low-dose CT image series. Methods: Unlike conventional local operations on neighboring image voxels, nonlocal means (NLM) algorithm utilizes the redundancy of information across the whole image. This paper adapts the NLM to utilize the redundancy of information in the previous normal-dose scan and further exploits ways to optimize the nonlocal weights for low-dose image restoration in the NLM framework. The resulting algorithm is called the previous normal-dose scan induced nonlocal means (ndiNLM). Because of the optimized nature of nonlocal weights calculation, the ndiNLM algorithm does not depend heavily on image registration between the current low-dose and the previous normal-dose CT scans. Furthermore, the smoothing parameter involved in the ndiNLM algorithm can be adaptively estimated based on the image noise relationship between the current low-dose and the previous normal-dose scanning protocols. Results: Qualitative and quantitative evaluations were carried out on a physical phantom as well as clinical abdominal and brain perfusion CT scans in terms of accuracy and resolution properties. The gain by the use

  3. Advanced Computational Approaches for Characterizing Stochastic Cellular Responses to Low Dose, Low Dose Rate Exposures

    SciTech Connect

    Scott, Bobby, R., Ph.D.

    2003-06-27

    OAK - B135 This project final report summarizes modeling research conducted in the U.S. Department of Energy (DOE), Low Dose Radiation Research Program at the Lovelace Respiratory Research Institute from October 1998 through June 2003. The modeling research described involves critically evaluating the validity of the linear nonthreshold (LNT) risk model as it relates to stochastic effects induced in cells by low doses of ionizing radiation and genotoxic chemicals. The LNT model plays a central role in low-dose risk assessment for humans. With the LNT model, any radiation (or genotoxic chemical) exposure is assumed to increase one¡¯s risk of cancer. Based on the LNT model, others have predicted tens of thousands of cancer deaths related to environmental exposure to radioactive material from nuclear accidents (e.g., Chernobyl) and fallout from nuclear weapons testing. Our research has focused on developing biologically based models that explain the shape of dose-response curves for low-dose radiation and genotoxic chemical-induced stochastic effects in cells. Understanding the shape of the dose-response curve for radiation and genotoxic chemical-induced stochastic effects in cells helps to better understand the shape of the dose-response curve for cancer induction in humans. We have used a modeling approach that facilitated model revisions over time, allowing for timely incorporation of new knowledge gained related to the biological basis for low-dose-induced stochastic effects in cells. Both deleterious (e.g., genomic instability, mutations, and neoplastic transformation) and protective (e.g., DNA repair and apoptosis) effects have been included in our modeling. Our most advanced model, NEOTRANS2, involves differing levels of genomic instability. Persistent genomic instability is presumed to be associated with nonspecific, nonlethal mutations and to increase both the risk for neoplastic transformation and for cancer occurrence. Our research results, based on

  4. Contraception. Low-dose pill launched.

    PubMed

    1993-01-01

    At a vibrant ceremony in Kampala, Uganda, the Minister of Women in Development, Youth and Culture launched the new low-dose oral contraceptive Pilplan which provides women more options for birth spacing. Diplomats, physicians, government officials, and business leaders attended the ceremony at the Sheraton Hotel Kampala. A dance group did an interpretation of "Women in Uganda: Gaining Momentum." The Minister considered the introduction of this new pill as a turning point for reproductive rights. A baseline survey among Ugandan women has shown that although almost all women were familiar with the pill, only 36% have ever used it and only 15% were currently using it. 80% thought that pill use was preferable to having an unplanned pregnancy. These findings convinced the Minister that ignorance and misconception keep women from using the pill. The government, health providers, and others need to educate women about Pilplan and how to use it correctly. A bilateral agreement between the Ministry of Health and USAID set in motion a social marketing project which has now launched two contraceptive methods: Pilplan in 1993 and the Protector condom in 1990. USAID vowed to continue to support Pilplan, particularly if men could also help in supporting birth spacing. A Uganda-based pharmaceutical firm will distribute Pilplan in Uganda through pharmacies, clinics, and health facilities. Pilplan targets all middle- to low-income women. PMID:12319754

  5. Low dose mercury toxicity and human health.

    PubMed

    Zahir, Farhana; Rizwi, Shamim J; Haq, Soghra K; Khan, Rizwan H

    2005-09-01

    Post Minamata incident there has been awareness about mercury toxicity even among the general public. Previous researches contributed a vast amount of data regarding acute mercury exposure, but gradually information about the low dose [Ninomiya, T., Ohmori, H., Hashimoto, K., Tsuruta, K., Ekino, S., 1995. Expansion of methylmercury poisoning outside minamata: an epidemiological study on chronic methylmercury poisoninig outside of Minamata. Environ. Res. 70 (1) 47-50; Lebel, J., Mergler, D., Lucotte, M., Amorim, M., Dolbec, J., Miranda, D., Arantes, G., Rheault, I., Pichet, P., 1996. Evidence of early nervous system dysfunction in Amazonian populations exposed to low-levels of methylmercury. Neurotoxicology 17 (1) 157-167] of mercury toxicity has been trickling in. With mercury contaminating rain-, ground- and sea-water no one is safe. Polluted water leads to mercury laced fish, meat and vegetable. In aquatic environments, inorganic mercury is microbiologically transformed into lipophilic organic compound 'methylmercury'. This transformation makes mercury more prone to biomagnification in food chains. Consequently, populations with traditionally high dietary intake of food originating from fresh or marine environment have highest dietary exposure to mercury. Extensive research done on locals across the globe have already established this, persons who routinely consume fish or a particular species of fish are at an increased risk of methylmercury poisoning. The easy access of the toxicant to man through multiple pathways air, water, food, cosmetic products and even vaccines increase the exposure. Foetus and children are more susceptible towards mercury toxicity. Mothers consuming diet containing mercury pass the toxicant to foetus and to infants through breast milk. Decreased performance in areas of motor function and memory has been reported among children exposed to presumably safe mercury levels. Similarly, disruption of attention, fine motor function and verbal

  6. [HEALTH PREDICTION INDICES OBTAINED WITH LOW-DOSE COMPUTER TOMOGRAPHY SCANS].

    PubMed

    Matkevich, E i; Sinitsyn, V e; Ivanov LV

    2015-01-01

    Purpose of the investigation was to make prognostic estimations of reductions in somatic morbidity and temporal disability, and tumor pathology using low-dose computer tomography (CT) scans and to compare with standard protocols. Mean effective radiation doses were determined based on the results of 1627 diagnostic CT investigations made in 2012-2014 at the Treatment and Rehabilitation Center of the Russian Ministry of Health. Low-dose CT scans of the head and thoracic, abdominal and small pelvis organs were obtained on a GE Discovery CT750 HD, and with the help of the ASIR and MBIR algorithms of iterative reconstruction. In comparison with a standard dose, a single CT scan with a dose reduced by 10-12 mSv predicts a decrease in total morbidity by 0.84-5.52% and temporal disability by 0.55-1.65% per 100 employees over a year; total risk of tumors and genetic effects reduced in 5 to 10 times, which may be equal to 40-90 cases per 100,000 of 30 y.o. males. PMID:26934792

  7. Low-dose-rate, low-dose irradiation delays neurodegeneration in a model of retinitis pigmentosa.

    PubMed

    Otani, Atsushi; Kojima, Hiroshi; Guo, Congrong; Oishi, Akio; Yoshimura, Nagahisa

    2012-01-01

    The existence of radiation hormesis is controversial. Several stimulatory effects of low-dose (LD) radiation have been reported to date; however, the effects on neural tissue or neurodegeneration remain unknown. Here, we show that LD radiation has a neuroprotective effect in mouse models of retinitis pigmentosa, a hereditary, progressive neurodegenerative disease that leads to blindness. Various LD radiation doses were administered to the eyes in a retinal degeneration mouse model, and their pathological and physiological effects were analyzed. LD gamma radiation in a low-dose-rate (LDR) condition rescues photoreceptor cell apoptosis both morphologically and functionally. The greatest effect was observed in a condition using 650 mGy irradiation and a 26 mGy/minute dose rate. Multiple rounds of irradiation strengthened this neuroprotective effect. A characteristic up-regulation (563%) of antioxidative gene peroxiredoxin-2 (Prdx2) in the LDR-LD-irradiated retina was observed compared to the sham-treated control retina. Silencing the Prdx2 using small-interfering RNA administration reduced the LDR-LD rescue effect on the photoreceptors. Our results demonstrate for the first time that LDR-LD irradiation has a biological effect in neural cells of living animals. The results support that radiation exhibits hormesis, and this effect may be applied as a novel therapeutic concept for retinitis pigmentosa and for other progressive neurodegenerative diseases regardless of the mechanism of degeneration involved. PMID:22074737

  8. How to perform low-dose computed tomography for renal colic in clinical practice.

    PubMed

    Gervaise, A; Gervaise-Henry, C; Pernin, M; Naulet, P; Junca-Laplace, C; Lapierre-Combes, M

    2016-04-01

    Computed tomography (CT) has become the reference technique in medical imaging for renal colic, to diagnose, plan treatment and explore differential diagnosis. Its main limitation is the radiation dose, especially as urinary stone disease tends to relapse and mainly affects young people. It is therefore essential to reduce the CT radiation dose when renal colic is suspected. The goal of this review was twofold. First, we wanted to show how to use low-dose CT in patients with suspected renal colic in current clinical practice. Second, we wished to discuss the different ways of reducing CT radiation dose by considering both behavioral and technological factors. Among the behavioral factors, limiting the scan coverage area is a straightforward and effective way to reduce the dose. Improvement of technological factors relies mainly on using automatic tube current modulation, lowering the tube voltage and current as well using iterative reconstruction. PMID:26522944

  9. Low dose irradiation profoundly affects transcriptome and microRNAme in rat mammary gland tissues

    PubMed Central

    Luzhna, Lidia; Kovalchuk, Olga

    2014-01-01

    Ionizing radiation has been successfully used in medical tests and treatment therapies for a variety of medical conditions. However, patients and health-care workers are greatly concerned about overexposure to medical ionizing radiation and possible cancer induction due to frequent mammographies and/or CT scans. Diagnostic imaging involves the use of low doses of ionizing radiation, and its potential carcinogenic role creates a cancer risk concern for exposed individuals. In this study, the effects of X-ray exposure of different doses on the gene expression patterns and the micro-RNA expression patterns in normal breast tissue were investigated in rats. Our results revealed the activation of immune response pathways upon low dose of radiation exposure. These included natural killer mediated cytotoxicity pathways, antigen processing and presentation pathways, chemokine signaling pathways, and T- and B-cell receptor signaling pathways. Both high and low doses of radiation led to miRNA expression alterations. Increased expression of miR-34a may be linked to cell cycle arrest and apoptosis. Up-regulation of miR-34a was correlated with down-regulation of its target E2F3 and up-regulation of p53. This data suggests that ionizing radiation at specific high and low doses leads to cell cycle arrest and a possible initiation of apoptosis. PMID:25594002

  10. Noise reduction by projection direction dependent diffusion for low dose fan-beam x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Tang, Shaojie; Mou, Xuanqin; Zhang, Yanbo; Yu, Hengyong

    2011-03-01

    We propose a novel method to reduce the noise in fan-beam computed tomography (CT) imaging. First, the inverse Radon transform is induced for a family of differential expression of projection function. Second, the diffusion partial differential equation (PDE) is generalized from image space to projection space in parallel-beam geometry. Third, the diffusion PDE is further induced from parallel-beam geometry to fan-beam geometry. Finally, the projection direction dependent diffusion is developed to reduce CT noise, which arises from the quantum variation in the low dose exposure of a medical x-ray CT (XCT) system. The proposed noise reduction processes projections iteratively and dependently on x-ray path position, followed by a general CT reconstruction. Numerical simulation studies have demonstrated its feasibility in the noise reduction of low dose fan-beam XCT imaging.

  11. Low dose four-dimensional computerized tomography with volume rendering reconstruction for primary hyperparathyroidism: How I do it?

    PubMed

    Platz, Timothy A; Kukar, Moshim; Elmarzouky, Rania; Cance, William; Abdelhalim, Ahmed

    2014-09-28

    Modification of 4-dimensional computed tomography (4D-CT) technique with volume rendering reconstructions and significant dose reduction is a safe and accurate method of pre-operative localization for primary hyperparathyroidism. Modified low dose 4D-CT with volume rendering reconstructions provides precise preoperative localization and is associated with a significant reduction in radiation exposure compared to classic preoperative localizing techniques. It should be considered the preoperative localization study of choice for primary hyperparathyroidism. PMID:25276315

  12. Quantification of Adaptive Protection Following Low-dose Irradiation.

    PubMed

    Feinendegen, Ludwig E

    2016-03-01

    The question whether low doses and low dose-rates of ionizing radiation pose a health risk to people is of public, scientific and regulatory concern. It is a subject of intense debate and causes much fear. The controversy is to what extent low-dose effects, if any, cause or protect against damage such as cancer. Even if immediate molecular damage in exposed biological systems rises linearly with the number of energy deposition events (i.e., with absorbed dose), the response of the whole biological system to that damage is not linear. To understand how initial molecular damage affects a complex living system is the current challenge. PMID:26808882

  13. Acute necrotising pancreatitis derived from low-dose corticosteroid use: an important reminder of clinical management.

    PubMed

    Sabre, Alexander; Guthrie, Morgan Mary; Maleknia, Reza

    2015-01-01

    Although the exact mechanism is unknown, incidence of drug-induced pancreatitis from corticosteroids is well established in the medical literature. Commonly reported in chronic steroid-dependent individuals who require large doses for a wide array of pathologies, the incidence of damage to the pancreas from low-doses have not been well described. We report a case of a 68-year-old woman who presented with severe abdominal pain, nausea and vomiting, 3 days after the initiation of low-dose methylprednisolone for osteoarthritis. Inpatient laboratory analysis revealed an elevated lipase of 1770 U/L and CT scan showing extensive necrotising pancreatitis involving the head, body and tail. Cessation of the causative medication and conservative treatment successfully led to resolution of symptoms. We present this case to inform clinicians of the precipitance of pancreatitis from modest strength corticosteroid management, so that more accurate and improved performance in pharmacological decisions can be made for patient care. PMID:26150628

  14. Risk of cancer subsequent to low-dose radiation

    SciTech Connect

    Warren, S.

    1980-01-01

    The author puts low dose irradiation risks in perspective using average background radiation doses for standards. He assailed irresponsible media coverage during the height of public interest in the Three-Mile Island Reactor incident. (PCS)

  15. Treatment of puberty trichotillomania with low-dose aripiprazole.

    PubMed

    Sasaki, Tsuyoshi; Iyo, Masaomi

    2015-01-01

    The present case is of a 14-year-old female with trichotillomania (TTM) that was treated with a low dose of aripiprazole (ARP) 1.5 mg/day. To our knowledge, this is the first published report to show an improvement of pubertal TTM using an ultra-low dose of ARP. In this case, a 50-mg fluvoxamine monotherapy for 2 years and a subsequent 4-month comprehensive cognitive behavioral therapy (CBT) monotherapy did not improve her hair-pulling symptoms. However, the treatment with a low-dose ARP of 1.5 mg/day dramatically improved her TTM symptoms without extrapyramidal symptoms. In this regard, low-dose ARP treatment for TTM might be a safe alternative to antidepressants, which carry the risk of agitation with suicidal ideation in adolescents. PMID:26089954

  16. Data of low-dose phase-based X-ray imaging for in situ soft tissue engineering assessments.

    PubMed

    Izadifar, Zohreh; Honaramooz, Ali; Wiebe, Sheldon; Belev, George; Chen, Xiongbiao; Chapman, Dean

    2016-03-01

    This article presents the data of using three phase-based X-ray imaging techniques to characterize biomaterial scaffold and soft tissues in situ, as reported in our study "Low-dose phase-based X-ray imaging techniques for in situ soft tissue engineering assessments" [1]. The examined parameters include the radiation dose, scan time, and image quality, which are all critical to longitudinal in situ live animal assessments. The data presented were obtained from three dimensional imaging of scaffolds in situ cartilage by means of synchrotron-based computed tomography-diffraction enhanced imaging (CT-DEI), analyzer based imaging (CT-ABI), and in-line phase contrast imaging (CT-PCI) at standard and low dose imaging modalities. PMID:26909381

  17. Data of low-dose phase-based X-ray imaging for in situ soft tissue engineering assessments

    PubMed Central

    Izadifar, Zohreh; Honaramooz, Ali; Wiebe, Sheldon; Belev, George; Chen, Xiongbiao; Chapman, Dean

    2016-01-01

    This article presents the data of using three phase-based X-ray imaging techniques to characterize biomaterial scaffold and soft tissues in situ, as reported in our study “Low-dose phase-based X-ray imaging techniques for in situ soft tissue engineering assessments” [1]. The examined parameters include the radiation dose, scan time, and image quality, which are all critical to longitudinal in situ live animal assessments. The data presented were obtained from three dimensional imaging of scaffolds in situ cartilage by means of synchrotron-based computed tomography-diffraction enhanced imaging (CT-DEI), analyzer based imaging (CT-ABI), and in-line phase contrast imaging (CT-PCI) at standard and low dose imaging modalities. PMID:26909381

  18. High signal intensity in dentate nucleus and globus pallidus on unenhanced T1-weighted MR images in three patients with impaired renal function and vascular calcification.

    PubMed

    Barbieri, Sebastiano; Schroeder, Christophe; Froehlich, Johannes M; Pasch, Andreas; Thoeny, Harriet C

    2016-05-01

    Gadolinium-based contrast agents (primarily those with linear chelates) are associated with a dose-dependent signal hyperintensity in the dentate nucleus and the globus pallidus on unenhanced T1-weighted MRI following administration to selected patients with normal renal function. The accumulation of gadolinium has also been reported in the skin, heart, liver, lung, and kidney of patients with impaired renal function suffering from nephrogenic systemic fibrosis (NSF). Here we report on three patients with impaired renal function and vascular calcification (two with confirmed NSF) whose unenhanced T1-weighted MRIs showed conspicuous high signal intensity in the dentate nucleus and the globus pallidus after they had been exposed to relatively low doses of linear gadolinium-based contrast agents (0.27, 0.45, and 0.68 mmol/kg). Signal ratios between dentate nucleus and pons and between globus pallidus and thalamus were comparable with previously reported measurements in subjects without renal impairment. Of note, all three analysed patients suffered from transient signs of neurological disorders of undetermined cause. In conclusion, the exposure to 0.27-0.68 mmol/kg of linear gadolinium-based contrast agent was associated with probable gadolinium accumulation in the brain of three patients suffering from impaired renal function and vascular calcification. © 2016 The Authors. Contrast Media & Molecular Imaging published by John Wiley & Sons Ltd. PMID:26929131

  19. Screening for lung cancer with low-dose computed tomography: a review of current status

    PubMed Central

    Bowman, Rayleen V.; Yang, Ian A.; Fong, Kwun M.; Berg, Christine D.

    2013-01-01

    Screening using low-dose computed tomography (CT) represents an exciting new development in the struggle to improve outcomes for people with lung cancer. Randomised controlled evidence demonstrating a 20% relative lung cancer mortality benefit has led to endorsement of screening by several expert bodies in the US and funding by healthcare providers. Despite this pivotal result, many questions remain regarding technical and logistical aspects of screening, cost-effectiveness and generalizability to other settings. This review discusses the rationale behind screening, the results of on-going trials, potential harms of screening and current knowledge gaps. PMID:24163745

  20. Low Dose Suppression of Neoplastic Transformation in Vitro

    SciTech Connect

    John Leslie Redpath

    2012-05-01

    This grant was to study the low dose suppression of neoplastic transformation in vitro and the shape of the dose-response curve at low doses and dose-rates of ionizing radiation. Previous findings had indicated a suppression of transformation at dose <10cGy of low-LET radiation when delivered at high dose-rate. The present study indicates that such suppression extends out to doses in excess of 100cGy when the dose (from I-125 photons) is delivered at dose-rates as low as 0.2 mGy/min and out to in excess of {approx}25cGy the highest dose studied at the very low dose-rate of 0.5 mGy/day. We also examined dose-rate effects for high energy protons (which are a low-LET radiation) and suppression was evident below {approx}10cGy for high dose-rate delivery and at least out to 50cGy for low dose-rate (20cGy/h) delivery. Finally, we also examined the effect of low doses of 1 GeV/n iron ions (a high-LET radiation) delivered at high dose-rate on transformation at low doses and found a suppression below {approx}10cGy that could be attributable to an adaptive response in bystander cells induced by the associated low-LET delta rays. These results have implications for cancer risk assessment at low doses.

  1. Low Dose Vaporized Cannabis Significantly Improves Neuropathic Pain

    PubMed Central

    Wilsey, Barth; Marcotte, Thomas D.; Deutsch, Reena; Gouaux, Ben; Sakai, Staci; Donaghe, Haylee

    2013-01-01

    We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling either medium dose (3.53%), low dose (1.29%), or placebo cannabis with the primary outcome being VAS pain intensity. Psychoactive side-effects, and neuropsychological performance were also evaluated. Mixed effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the two active dose groups’ results (p>0.7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo vs. low dose, 2.9 for placebo vs. medium dose, and 25 for medium vs. low dose. As these NNT are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being, for all intents and purposes, as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well-tolerated, and neuropsychological effects were of limited duration and readily reversible within 1–2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain. PMID:23237736

  2. Low-Dose Risk, Decisions, and Risk Communication

    SciTech Connect

    Flynn, James; Slovic, Paul

    2001-06-01

    To conduct basic research on how people receive, evaluate, and form positions on scientific information and its relationship to low-dose radiation exposure. There are three major areas of study in our research program. First is the development of theories, frameworks and concepts essential to guiding data collection and analysis. The second area is a program of experimental studies on risk perception, evaluation of science information, and the structure of individual positions regarding low dose exposures. This involves the study of existing knowledge and the evaluation of science information presented within a variety of formats, as educational information, news media stories, and alternative communication methods (personal contact, small group interaction, email & internet, etc.). Third is the community-level studies to examine and record how the social conditions, under which science communications take place, influence the development of attitudes and opinions about: low- dose exposures, the available management options, control of radiation risks, and preferences for program and policy goals.

  3. Low doses of arsenic, via perturbing p53, promotes tumorigenesis.

    PubMed

    Ganapathy, Suthakar; Li, Ping; Fagman, Johan; Yu, Tianqi; Lafontant, Jean; Zhang, Guojun; Chen, Changyan

    2016-09-01

    In drinking water and in workplace or living environments, low doses of arsenic can exist and operate as a potent carcinogen. Due to insufficient understanding and information on the pervasiveness of environmental exposures to arsenic, there is an urgent need to elucidate the underlying molecular mechanisms of arsenic regarding its carcinogenic effect on human health. In this study, we demonstrate that low doses of arsenic exposure mitigate or mask p53 function and further perturb intracellular redox state, which triggers persistent endoplasmic reticulum (ER) stress and activates UPR (unfolded protein response), leading to transformation or tumorigenesis. Thus, the results suggest that low doses of arsenic exposure, through attenuating p53-regulated tumor suppressive function, change the state of intracellular redox and create a microenvironment for tumorigenesis. Our study also provides the information for designing more effective strategies to prevent or treat human cancers initiated by arsenic exposure. PMID:27425828

  4. [Low-dose radiation effects and intracellular signaling pathways].

    PubMed

    Suzuki, Keiji; Kodama, Seiji; Watanabe, Masami

    2006-10-01

    Accumulated evidence has shown that exposure to low-dose radiation, especially doses less than 0.1 Gy, induces observable effects on mammalian cells. However, the underlying molecular mechanisms have not yet been clarified. Recently, it has been shown that low-dose radiation stimulates growth factor receptor, which results in a sequential activation of the mitogen-activated protein kinase pathway. In addition to the activation of the membrane-bound pathways, it is becoming evident that nuclear pathways are also activated by low-dose radiation. Ionizing radiation has detrimental effects on chromatin structure, since radiation-induced DNA double-strand breaks result in discontinuity of nucleosomes. Recently, it has been shown that ATM protein, the product of the ATM gene mutated in ataxia-telangiectasia, recognizes alteration in the chromatin structure, and it is activated through intermolecular autophosphorylation at serine 1981. Using antibodies against phosphorylated ATM, we found that the activated and phosphorylated ATM protein is detected as discrete foci in the nucleus between doses of 10 mGy and 1 Gy. Interestingly, the size of the foci induced by low-dose radiation was equivalent to the foci induced by high-dose radiation. These results indicate that the initial signal is amplified through foci growth, and cells evolve a system by which they can respond to a small number of DNA double-strand breaks. From these results, it can be concluded that low-dose radiation is sensed both in the membrane and in the nucleus, and activation of multiple signal transduction pathways could be involved in manifestations of low-dose effects. PMID:17016017

  5. Low-dose radiation epidemiology studies: status and issues.

    PubMed

    Shore, Roy E

    2009-11-01

    Although the Japanese atomic bomb study and radiotherapy studies have clearly documented cancer risks from high-dose radiation exposures, radiation risk assessment groups have long recognized that protracted or low exposures to low-linear energy transfer radiations are key radiation protection concerns because these are far more common than high-exposure scenarios. Epidemiologic studies of human populations with low-dose or low dose-rate exposures are one approach to addressing those concerns. A number of large studies of radiation workers (Chernobyl clean-up workers, U.S. and Chinese radiological technologists, and the 15-country worker study) or of persons exposed to environmental radiation at moderate to low levels (residents near Techa River, Semipalatinsk, Chernobyl, or nuclear facilities) have been conducted. A variety of studies of medical radiation exposures (multiple-fluoroscopy, diagnostic (131)I, scatter radiation doses from radiotherapy, etc.) also are of interest. Key results from these studies are summarized and compared with risk estimates from the Japanese atomic bomb study. Ideally, one would like the low-dose and low dose-rate studies to guide radiation risk estimation regarding the shape of the dose-response curve, DDREF (dose and dose-rate effectiveness factor), and risk at low doses. However, the degree to which low-dose studies can do so is subject to various limitations, especially those pertaining to dosimetric uncertainties and limited statistical power. The identification of individuals who are particularly susceptible to radiation cancer induction also is of high interest in terms of occupational and medical radiation protection. Several examples of studies of radiation-related cancer susceptibility are discussed, but none thus far have clearly identified radiation-susceptible genotypes. PMID:19820457

  6. LOW-DOSE RISK, DECISIONS, AND RISK COMMUNICATION

    EPA Science Inventory

    This grant application seeks funding for a program of basic research in the areas of risk perception and decision making as applied to the role of communication of biological research results on low-dose radiation exposure. Widespread adverse views about radiation exposure makes...

  7. FINAL REPORT: LOW DOSE RISK, DECISIONS, AND RISK COMMUNICATION

    EPA Science Inventory

    The research project conducted basic research on how people receive, evaluate, and form positions in response to scientific information and its relationship to low-dose radiation exposure. Three major areas of study were addressed in our research program. First was the developmen...

  8. Malignant melanoma of the tongue following low-dose radiation

    SciTech Connect

    Kalemeris, G.C.; Rosenfeld, L.; Gray, G.F. Jr.; Glick, A.D.

    1985-03-01

    A 47-year-old man had a spindly malignant melanoma of the tongue many years after low-dose radiation therapy for lichen planus. To our knowledge, only 12 melanomas of the tongue have been reported previously, and in none of these was radiation documented.

  9. PROGRESS REPORT. LOW-DOSE RISK, DECISIONS, AND RISK COMMUNICATION

    EPA Science Inventory

    The objectives of this research are to conduct basic research on how people receive, evaluate, and form positions on scientific information and its relationship to low-dose radiation exposure. There are three major areas of study in our research program. First is the development ...

  10. LOW-DOSE RISK, DECISIONS, AND RISK COMMUNICATION: YEAR 3

    EPA Science Inventory

    The objective of this project is to conduct basic research on how people receive, evaluate, and form positions on scientific information and its relationship to low-dose radiation exposure. There are three major areas of study in our research program. First is the development of ...

  11. Glyphosate Applied at Low Doses Can Stimulate Plant Growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Glyphosate blocks the shikimic acid pathway, inhibiting the production of aromatic amino acids and several secondary compounds derived from these amino acids. Non-target plants can be exposed to low doses of glyphosate by herbicide drift of spray droplets and contact with treated weeds. Previous s...

  12. Low dose ethanol consumption improves insulin sensitivity in rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While chronic consumption of high doses of ethanol is well known to have adverse health consequences, intake of low doses have been reported to improve several markers of health outcomes. Published results from our laboratory using total enteral nutrition (TEN) in rats, in which ethanol-containing d...

  13. Mechanisms of Low Dose Radio-Suppression of Genomic Instability

    SciTech Connect

    Engelward, Bevin P

    2009-09-16

    The major goal of this project is to contribute toward the elucidation of the impact of long term low dose radiation on genomic stability. We have created and characterized novel technologies for delivering long term low dose radiation to animals, and we have studied genomic stability by applying cutting edge molecular analysis technologies. Remarkably, we have found that a dose rate that is 300X higher than background radiation does not lead to any detectable genomic damage, nor is there any significant change in gene expression for genes pertinent to the DNA damage response. These results point to the critical importance of dose rate, rather than just total dose, when evaluating public health risks and when creating regulatory guidelines. In addition to these studies, we have also further developed a mouse model for quantifying cells that have undergone a large scale DNA sequence rearrangement via homologous recombination, and we have applied these mice in studies of both low dose radiation and space radiation. In addition to more traditional approaches for assessing genomic stability, we have also explored radiation and possible beneficial effects (adaptive response), long term effects (persistent effects) and effects on communication among cells (bystander effects), both in vitro and in vivo. In terms of the adaptive response, we have not observed any significant induction of an adaptive response following long term low dose radiation in vivo, delivered at 300X background. In terms of persistent and bystander effects, we have revealed evidence of a bystander effect in vivo and with researchers at and demonstrated for the first time the molecular mechanism by which cells “remember” radiation exposure. Understanding the underlying molecular mechanisms by which radiation can induce genomic instability is fundamental to our ability to assess the biological impact of low dose radiation. Finally, in a parallel set of studies we have explored the effects of heavy

  14. Mechanical Solitaire Thrombectomy with Low-Dose Booster Tirofiban Injection

    PubMed Central

    Goh, Duck-Ho; Jeong, Hae Woong; Ha, Sam Yeol

    2016-01-01

    Purpose Mechanical thrombectomy using a Solitaire stent has been associated with a high recanalization rate and favorable clinical outcome in intra-arterial thrombolysis. To achieve a higher recanalization rate for mechanical Solitaire thrombectomy, we used an intra-arterial low-dose booster tirofiban injection into the occluded segment after stent deployment. We report the safety and recanalization rates for mechanical Solitaire thrombectomy with a low-dose booster tirofiban injection. Materials and Methods Between February and March 2013, 13 consecutive patients underwent mechanical Solitaire thrombectomy with low-dose booster tirofiban injection. The occlusion sites included the proximal middle cerebral artery (5 patients), the internal carotid artery (5 patients), the top of the basilar artery (2 patients) and the distal middle cerebral artery (M2 segment, 1 patient). Six patients underwent bridge treatment, including intravenous tissue plasminogen activator. Tirofiban of 250 µg was used in all patients except one (500 µg). All occluded vessels were recanalized after 3 attempts at stent retrieval (1 time, n=9; 2 times, n=2; 3 times, n=2). Results Successful recanalization was achieved in all patients (TICI 3, n=8; TICI 2b, n=5). Procedural complications developed in 3 patients (subarachnoid hemorrhage, n=2; hemorrhagic transformation, n=1). Mortality occurred in one patient with a basilar artery occlusion due to reperfusion brain swelling after mechanical Solitaire thrombectomy with low-dose booster tirofiban injection. Favorable clinical outcome (mRS≤2) was observed in 8 patients (61.5%). Conclusion Our modified mechanical Solitaire thrombectomy method using a low-dose booster tirofiban injection might enhance the recanalization rate with no additive hemorrhagic complications. PMID:27621948

  15. Organ Dose and Attributable Cancer Risk in Lung Cancer Screening with Low-Dose Computed Tomography

    PubMed Central

    Saltybaeva, Natalia; Martini, Katharina; Frauenfelder, Thomas; Alkadhi, Hatem

    2016-01-01

    Purpose Lung cancer screening with CT has been recently recommended for decreasing lung cancer mortality. The radiation dose of CT, however, must be kept as low as reasonably achievable for reducing potential stochastic risks from ionizing radiation. The purpose of this study was to calculate individual patients’ lung doses and to estimate cancer risks in low-dose CT (LDCT) in comparison with a standard dose CT (SDCT) protocol. Materials and Methods This study included 47 adult patients (mean age 63.0 ± 5.7 years) undergoing chest CT on a third-generation dual-source scanner. 23/47 patients (49%) had a non-enhanced chest SDCT, 24 patients (51%) underwent LDCT at 100 kVp with spectral shaping at a dose equivalent to a chest x-ray. 3D-dose distributions were obtained from Monte Carlo simulations for each patient, taking into account their body size and individual CT protocol. Based on the dose distributions, patient-specific lung doses were calculated and relative cancer risk was estimated according to BEIR VII recommendations. Results As compared to SDCT, the LDCT protocol allowed for significant organ dose and cancer risk reductions (p<0.001). On average, lung dose was reduced from 7.7 mGy to 0.3 mGy when using LDCT, which was associated with lowering of the cancer risk from 8.6 to 0.35 per 100’000 cases. A strong linear correlation between lung dose and patient effective diameter was found for both protocols (R2 = 0.72 and R2 = 0.75 for SDCT and LDCT, respectively). Conclusion Use of a LDCT protocol for chest CT with a dose equivalent to a chest x-ray allows for significant lung dose and cancer risk reduction from ionizing radiation. PMID:27203720

  16. Investigation of lung nodule detectability in low-dose 320-slice computed tomography

    PubMed Central

    Silverman, J. D.; Paul, N. S.; Siewerdsen, J. H.

    2009-01-01

    Low-dose imaging protocols in chest CT are important in the screening and surveillance of suspicious and indeterminate lung nodules. Techniques that maintain nodule detectability yet permit dose reduction, particularly for large body habitus, were investigated. The objective of this study was to determine the extent to which radiation dose can be minimized while maintaining diagnostic performance through knowledgeable selection of reconstruction techniques. A 320-slice volumetric CT scanner (Aquilion ONE™, Toshiba Medical Systems) was used to scan an anthropomorphic phantom at doses ranging from ∼0.1 mGy up to that typical of low-dose CT (LDCT, ∼5 mGy) and diagnostic CT (∼10 mGy). Radiation dose was measured via Farmer chamber and MOSFET dosimetry. The phantom presented simulated nodules of varying size and contrast within a heterogeneous background, and chest thickness was varied through addition of tissue-equivalent bolus about the chest. Detectability of a small solid lung nodule (3.2 mm diameter, −37 HU, typically the smallest nodule of clinical significance in screening and surveillance) was evaluated as a function of dose, patient size, reconstruction filter, and slice thickness by means of nine-alternative forced-choice (9AFC) observer tests to quantify nodule detectability. For a given reconstruction filter, nodule detectability decreased sharply below a threshold dose level due to increased image noise, especially for large body size. However, nodule detectability could be maintained at lower doses through knowledgeable selection of (smoother) reconstruction filters. For large body habitus, optimal filter selection reduced the dose required for nodule detection by up to a factor of ∼3 (from ∼3.3 mGy for sharp filters to ∼1.0 mGy for the optimal filter). The results indicate that radiation dose can be reduced below the current low-dose (5 mGy) and ultralow-dose (1 mGy) levels with knowledgeable selection of reconstruction parameters. Image

  17. Standardization and Optimization of Computed Tomography Protocols to Achieve Low-Dose

    PubMed Central

    Chin, Cynthia; Cody, Dianna D.; Gupta, Rajiv; Hess, Christopher P.; Kalra, Mannudeep K.; Kofler, James M.; Krishnam, Mayil S.; Einstein, Andrew J.

    2014-01-01

    The increase in radiation exposure due to CT scans has been of growing concern in recent years. CT scanners differ in their capabilities and various indications require unique protocols, but there remains room for standardization and optimization. In this paper we summarize approaches to reduce dose, as discussed in lectures comprising the first session of the 2013 UCSF Virtual Symposium on Radiation Safety in Computed Tomography. The experience of scanning at low dose in different body regions, for both diagnostic and interventional CT procedures, is addressed. An essential primary step is justifying the medical need for each scan. General guiding principles for reducing dose include tailoring a scan to a patient, minimizing scan length, use of tube current modulation and minimizing tube current, minimizing-tube potential, iterative reconstruction, and periodic review of CT studies. Organized efforts for standardization have been spearheaded by professional societies such as the American Association of Physicists in Medicine. Finally, all team members should demonstrate an awareness of the importance of minimizing dose. PMID:24589403

  18. Influence of low-dose and low-dose-rate ionizing radiation on mutation induction in human cells

    NASA Astrophysics Data System (ADS)

    Yatagai, F.; Umebayashi, Y.; Suzuki, M.; Abe, T.; Suzuki, H.; Shimazu, T.; Ishioka, N.; Iwaki, M.; Honma, M.

    This is a review paper to introduce our recent studies on the genetic effects of low-dose and low-dose-rate ionizing radiation (IR). Human lymphoblastoid TK6 cells were exposed to γ-rays at a dose-rate of 1.2 mGy/h (total 30 mGy). The frequency of early mutations (EMs) in the thymidine kinase ( TK) gene locus was determined to be 1.7 × 10 -6, or 1.9-fold higher than the level seen in unirradated controls [Umebayashi, Y., Honma, M., Suzuki, M., Suzuki, H., Shimazu, T., Ishioka, N., Iwaki, M., Yatagai, F., Mutation induction in cultured human cells after low-dose and low-dose-rate γ-ray irradiation: detection by LOH analysis. J. Radiat. Res., 48, 7-11, 2007]. These mutants were then analyzed for loss of heterozygosity (LOH) events. Small interstitial-deletion events were restricted to the TK gene locus and were not observed in EMs in unirradated controls, but they comprised about half of the EMs (8/15) after IR exposure. Because of the low level of exposure to IR, this specific type of event cannot be considered to be the direct result of an IR-induced DNA double strand break (DSB). To better understand the effects of low-level IR exposure, the repair efficiency of site-specific chromosomal DSBs was also examined. The pre γ-irradiation under the same condition did not largely influence the efficiency of DSB repair via end-joining, but enhanced such efficiency via homologous recombination to an about 40% higher level (unpublished data). All these results suggest that DNA repair and mutagenesis can be indirectly influenced by low-dose/dose-rate IR.

  19. SU-F-18C-15: Model-Based Multiscale Noise Reduction On Low Dose Cone Beam Projection

    SciTech Connect

    Yao, W; Farr, J

    2014-06-15

    Purpose: To improve image quality of low dose cone beam CT for patient positioning in radiation therapy. Methods: In low dose cone beam CT (CBCT) imaging systems, Poisson process governs the randomness of photon fluence at x-ray source and the detector because of the independent binomial process of photon absorption in medium. On a CBCT projection, the variance of fluence consists of the variance of noiseless imaging structure and that of Poisson noise, which is proportional to the mean (noiseless) of the fluence at the detector. This requires multiscale filters to smoothen noise while keeping the structure information of the imaged object. We used a mathematical model of Poisson process to design multiscale filters and established the balance of noise correction and structure blurring. The algorithm was checked with low dose kilo-voltage CBCT projections acquired from a Varian OBI system. Results: From the investigation of low dose CBCT of a Catphan phantom and patients, it showed that our model-based multiscale technique could efficiently reduce noise and meanwhile keep the fine structure of the imaged object. After the image processing, the number of visible line pairs in Catphan phantom scanned with 4 ms pulse time was similar to that scanned with 32 ms, and soft tissue structure from simulated 4 ms patient head-and-neck images was also comparable with scanned 20 ms ones. Compared with fixed-scale technique, the image quality from multiscale one was improved. Conclusion: Use of projection-specific multiscale filters can reach better balance on noise reduction and structure information loss. The image quality of low dose CBCT can be improved by using multiscale filters.

  20. Low Dose, Low Energy 3d Image Guidance during Radiotherapy

    NASA Astrophysics Data System (ADS)

    Moore, C. J.; Marchant, T.; Amer, A.; Sharrock, P.; Price, P.; Burton, D.

    2006-04-01

    Patient kilo-voltage X-ray cone beam volumetric imaging for radiotherapy was first demonstrated on an Elekta Synergy mega-voltage X-ray linear accelerator. Subsequently low dose, reduced profile reconstruction imaging was shown to be practical for 3D geometric setup registration to pre-treatment planning images without compromising registration accuracy. Reconstruction from X-ray profiles gathered between treatment beam deliveries was also introduced. The innovation of zonal cone beam imaging promises significantly reduced doses to patients and improved soft tissue contrast in the tumour target zone. These developments coincided with the first dynamic 3D monitoring of continuous body topology changes in patients, at the moment of irradiation, using a laser interferometer. They signal the arrival of low dose, low energy 3D image guidance during radiotherapy itself.

  1. Patient release criteria for low dose rate brachytherapy implants.

    PubMed

    Boyce, Dale E; Sheetz, Michael A

    2013-04-01

    A lack of consensus regarding a model governing the release of patients following sealed source brachytherapy has led to a set of patient release policies that vary from institution to institution. The U.S. Nuclear Regulatory Commission has issued regulatory guidance on patient release in NUREG 1556, Volume 9, Rev. 2, Appendix U, which allows calculation of release limits following implant brachytherapy. While the formalism presented in NUREG is meaningful for the calculation of release limits in the context of relatively high energy gamma emitters, it does not estimate accurately the effective dose equivalent for the common low dose rate brachytherapy sources Cs, I, and Pd. NUREG 1556 states that patient release may be based on patient-specific calculations as long as the calculation is documented. This work is intended to provide a format for patient-specific calculations to be used for the consideration of patients' release following the implantation of certain low dose rate brachytherapy isotopes. PMID:23439145

  2. Responses of astrocytes in culture after low dose laser irradiation

    SciTech Connect

    Yew, D.T.; Zheng, D.R.; Au, C.; Li, W.W. )

    1990-03-01

    The effect of Helium-Neon low dose laser on astrocytes was investigated in cultures of isolated astrocytes from albino neonatal rats. The laser appeared to inhibit the growth of astrocytes as exemplified by the smaller sizes of the cells and the decreased leucine uptake in each cell after treatment. Temporary decrease in the number of mitoses was also observed, but this trend was reversed soon after. Electron microscopic studies revealed an increase in buddings from cell bodies and processes (branches) after irradiation.

  3. Torsade de pointes and low-dose oral haloperidol.

    PubMed

    Jackson, T; Ditmanson, L; Phibbs, B

    1997-09-22

    Haloperidol, used to treat patients with psychoses, is considered minimally cardiotoxic. Several cases of torsade de pointes have been reported in association with the use of oral haloperidol. In each of those cases, a prolonged QTc preceded the torsade de pointes episode and thus may be considered a predictor for ventricular arrhythmias in elderly women treated with haloperidol. However, the following case may demonstrate the inability to predict an episode of torsade de pointes with low-dose oral haloperidol use. PMID:9308514

  4. Analysis of low-dose radiation shield effectiveness of multi-gate polymeric sheets

    NASA Astrophysics Data System (ADS)

    Kim, S. C.; Lee, H. K.; Cho, J. H.

    2014-07-01

    Computed tomography (CT) uses a high dose of radiation to create images of the body. As patients are exposed to radiation during a CT scan, the use of shielding materials becomes essential in CT scanning. This study was focused on the radiation shielding materials used for patients during a CT scan. In this study, sheets were manufactured to shield the eyes and the thyroid, the most sensitive parts of the body, against radiation exposure during a CT scan. These sheets are manufactured using silicone polymers, barium sulfate (BaSO4) and tungsten, with the aim of making these sheets equally or more effective in radiation shielding and more cost-effective than lead sheets. The use of barium sulfate drew more attention than tungsten due to its higher cost-effectiveness. The barium sulfate sheets were coated to form a multigate structure by applying the maximum charge rate during the agitator and subsequent mixing processes and creating multilayered structures on the surface. To measure radiation shielding effectiveness, the radiation dose was measured around both eyes and the thyroid gland using sheets in three different thicknesses (1, 2 and 3 mm). Among the 1 and 2 mm sheets, the Pb sheets exhibited greater effectiveness in radiation shielding around both eyes, but the W sheets were more effective in radiation shielding around the thyroid gland. In the 3 mm sheets, the Pb sheet also attenuated a higher amount of radiation around both eyes while the W sheet was more effective around the thyroid gland. In conclusion, the sheets made from barium sulfate and tungsten proved highly effective in shielding against low-dose radiation in CT scans without causing ill-health effects, unlike lead.

  5. Therapeutic rationale for low dose doxepin in insomnia patients

    PubMed Central

    Katwala, Jigar; Kumar, Ananda K; Sejpal, Jaykumar J; Terrence, Marcelle; Mishra, Manish

    2013-01-01

    Histamine is an excitatory neurotransmitter in central nervous system. It plays an important role in the regulation of the sleep-wake cycle. Antidepressant with sleep-promoting effects, for example, doxepin, promotes sleep not through a sedative action but through resynchronisation of circadian cycle. The stimulation of the H1 receptor is thought to play an important role in mediating arousal. Doxepin has a high affinity for the H1 receptor, making it a selective H1 antagonist at low dose and it has been shown to display sedating properties. Compared to other sedative antidepressant, low dose doxepin is the only tricyclic drug which has been evaluated by well-designed, randomised, double blind, placebo controlled studies in both adult and elderly patients. Doxepin is not designated as controlled substance/unscheduled drugs and thus may be of special advantage to use in patients with a history of substance abuse. Hence, well-documented therapeutic efficacy, tolerability and lack of important adverse effects make the low dose doxepin as a unique, rational drug for the treatment of insomnia in adult and elderly patients.

  6. MELODI: the 'Multidisciplinary European Low-Dose Initiative'.

    PubMed

    Belli, M; Salomaa, S; Ottolenghi, A

    2011-02-01

    The importance of research to reduce uncertainties in risk assessment of low and protracted exposures is now recognised globally. In Europe a new initiative, called 'Multidisciplinary European LOw Dose Initiative' (MELODI), has been proposed by a 'European High Level and Expert Group on low-dose risk research' (www.hleg.de), aimed at integrating national and EC (Euratom) efforts. Five national organisations: BfS (DE), CEA (FR), IRSN (FR), ISS (IT) and STUK (FI), with the support of the EC, have initiated the creation of MELODI by signing a letter of intent. In the forthcoming years, MELODI will integrate in a step-by-step approach EU institutions with significant programmes in the field and will be open to other scientific organisations and stakeholders. A key role of MELODI is to develop and maintain over time a strategic research agenda (SRA) and a road map of scientific priorities within a multidisciplinary approach, and to transfer the results for the radiation protection system. Under the coordination of STUK a network has been proposed in the 2009 Euratom Programme, called DoReMi (Low-Dose Research towards Mutidisciplinary Integration), which can help the integration process within the MELODI platform. DoReMi and the First MELODI Open Workshop, organised by BfS in September 2009, are now important inputs for the European SRA. PMID:21106638

  7. Exercise and sport performance with low doses of caffeine.

    PubMed

    Spriet, Lawrence L

    2014-11-01

    Caffeine is a popular work-enhancing supplement that has been actively researched since the 1970s. The majority of research has examined the effects of moderate to high caffeine doses (5-13 mg/kg body mass) on exercise and sport. These caffeine doses have profound effects on the responses to exercise at the whole-body level and are associated with variable results and some undesirable side effects. Low doses of caffeine (<3 mg/kg body mass, ~200 mg) are also ergogenic in some exercise and sport situations, although this has been less well studied. Lower caffeine doses (1) do not alter the peripheral whole-body responses to exercise; (2) improve vigilance, alertness, and mood and cognitive processes during and after exercise; and (3) are associated with few, if any, side effects. Therefore, the ergogenic effect of low caffeine doses appears to result from alterations in the central nervous system. However, several aspects of consuming low doses of caffeine remain unresolved and suffer from a paucity of research, including the potential effects on high-intensity sprint and burst activities. The responses to low doses of caffeine are also variable and athletes need to determine whether the ingestion of ~200 mg of caffeine before and/or during training and competitions is ergogenic on an individual basis. PMID:25355191

  8. Low-dose prophylactic craniospinal radiotherapy for intracranial germinoma

    SciTech Connect

    Schoenfeld, Gordon O.; Amdur, Robert J. . E-mail: amdurrj@ufl.edu; Schmalfuss, Ilona M.; Morris, Christopher G.; Keole, Sameer R.; Mendenhall, William M.; Marcus, Robert B.

    2006-06-01

    Purpose: To report outcomes of patients with localized intracranial germinoma treated with low-dose craniospinal irradiation (CSI) followed by a boost to the ventricular system and primary site. Methods and Materials: Thirty-one patients had pathologically confirmed intracranial germinoma and no spine metastases. Low-dose CSI was administered in 29 patients: usually 21 Gy of CSI, 9.0 Gy of ventricular boost, and a 19.5-Gy tumor boost, all at 1.5 Gy per fraction. Our neuroradiologist recorded three-dimensional tumor size on magnetic resonance images before, during, and after radiotherapy. Results: With a median follow-up of 7.0 years, 29 of 31 patients (94%) are disease free. One failure had nongerminomatous histology; the initial diagnosis was a sampling error. Of 3 patients who did not receive CSI, 1 died. No patient developed myelopathy, visual deficits, dementia, or skeletal growth problems. In locally controlled patients, tumor response according to magnetic resonance scan was nearly complete within 6 months after radiotherapy. Conclusions: Radiotherapy alone with low-dose prophylactic CSI cures almost all patients with localized intracranial germinoma. Complications are rare when the daily dose of radiotherapy is limited to 1.5 Gy and the total CSI dose to 21 Gy. Patients without a near-complete response to radiotherapy should undergo resection to rule out a nongerminomatous element.

  9. Randomized Controlled Trial of Low-Dose Estradiol and the SNRI Venlafaxine for Vasomotor Symptoms

    PubMed Central

    Joffe, Hadine; Guthrie, Katherine A.; LaCroix, Andrea Z.; Reed, Susan D.; Ensrud, Kristine E.; Manson, JoAnn E.; Newton, Katherine M.; Freeman, Ellen W.; Anderson, Garnet L.; Larson, Joseph C.; Hunt, Julie; Shifren, Jan; Rexrode, Kathryn M.; Caan, Bette; Sternfeld, Barbara; Carpenter, Janet S.; Cohen, Lee

    2014-01-01

    venlafaxine; p=0.09). Treatment satisfaction was highest (69%) on estradiol (p<0.001 versus placebo), lowest (39%) on placebo, and intermediate (52%) for venlafaxine (p=0.06 versus placebo). Both interventions were well tolerated. Conclusions Low-dose oral estradiol and venlafaxine are both effective treatments for vasomotor symptoms in midlife women. While efficacy of low-dose estradiol may be slightly superior to that of venlafaxine, the difference is small in magnitude and of uncertain clinical relevance. Clinicaltrials.gov identifier NCT01418209, http://clinicaltrials.gov/ct2/show/NCT01418209?term=NCT01418209&rank=1 PMID:24861828

  10. Induction of reciprocal translocations in rhesus monkey stem-cell spermatogonia: effects of low doses and low dose rates

    SciTech Connect

    van Buul, P.P.; Richardson, J.F. Jr.; Goudzwaard, J.H.

    1986-01-01

    The induction of reciprocal translocation in rhesus monkey spermatogonial stem cells was studied following exposure to low doses of acute X rays (0.25 Gy, 300 mGy/min) or to low-dose-rate X rays (1 Gy, 2 mGy/min) and gamma rays (1 Gy, 0.2 mGy/min). The results obtained at 0.25 Gy of X rays fitted exactly the linear extrapolation down from the 0.5 and 1.0 Gy points obtained earlier. Extension of X-ray exposure reduced the yield of translocations similar to that in the mouse by about 50%. The reduction to 40% of translocation rate after chronic gamma exposure was clearly less than the value of about 80% reported for the mouse over the same range of dose rates. Differential cell killing with ensuing differential elimination of aberration-carrying cells is the most likely explanation for the differences between mouse and monkey.

  11. Arsenic, mode of action at biologically plausible low doses: What are the implications for low dose cancer risk?

    SciTech Connect

    Snow, Elizabeth T. . E-mail: esnow@deakin.edu.au; Sykora, Peter; Durham, Troy R.; Klein, Catherine B.

    2005-09-01

    Arsenic is an established human carcinogen. However, there has been much controversy about the shape of the arsenic response curve, particularly at low doses. This controversy has been exacerbated by the fact that the mechanism(s) of arsenic carcinogenesis are still unclear and because there are few satisfactory animal models for arsenic-induced carcinogenesis. Recent epidemiological studies have shown that the relative risk for cancer among populations exposed to {<=}60 ppb As in their drinking water is often lower than the risk for the unexposed control population. We have found that treatment of human keratinocyte and fibroblast cells with 0.1 to 1 {mu}M arsenite (As{sup III}) also produces a low dose protective effect against oxidative stress and DNA damage. This response includes increased transcription, protein levels and enzyme activity of several base excision repair genes, including DNA polymerase {beta} and DNA ligase I. At higher concentrations (> 10 {mu}M), As induces down-regulation of DNA repair, oxidative DNA damage and apoptosis. This low dose adaptive (protective) response by a toxic agent is known as hormesis and is characteristic of many agents that induce oxidative stress. A mechanistic model for arsenic carcinogenesis based on these data would predict that the low dose risk for carcinogenesis should be sub-linear. The threshold dose where toxicity outweighs protection is hard to predict based on in vitro dose response data, but might be estimated if one could determine the form (metabolite) and concentration of arsenic responsible for changes in gene regulation in the target tissues.

  12. New approach for food allergy management using low-dose oral food challenges and low-dose oral immunotherapies.

    PubMed

    Yanagida, Noriyuki; Okada, Yu; Sato, Sakura; Ebisawa, Motohiro

    2016-04-01

    A number of studies have suggested that a large subset of children (approximately 70%) who react to unheated milk or egg can tolerate extensively heated forms of these foods. A diet that includes baked milk or egg is well tolerated and appears to accelerate the development of regular milk or egg tolerance when compared with strict avoidance. However, the indications for an oral food challenge (OFC) using baked products are limited for patients with high specific IgE values or large skin prick test diameters. Oral immunotherapies (OITs) are becoming increasingly popular for the management of food allergies. However, the reported efficacy of OIT is not satisfactory, given the high frequency of symptoms and requirement for long-term therapy. With food allergies, removing the need to eliminate a food that could be consumed in low doses could significantly improve quality of life. This review discusses the importance of an OFC and OIT that use low doses of causative foods as the target volumes. Utilizing an OFC or OIT with a low dose as the target volume could be a novel approach for accelerating the tolerance to causative foods. PMID:26774524

  13. Measurement uncertainty analysis of low-dose-rate prostate seed brachytherapy: post-implant dosimetry.

    PubMed

    Gregory, Kent J; Pattison, John E; Bibbo, Giovanni

    2015-03-01

    The minimal dose covering 90 % of the prostate volume--D 90--is arguably the most important dosimetric parameter in low-dose-rate prostate seed brachytherapy. In this study an analysis of the measurement uncertainties in D 90 from low-dose-rate prostate seed brachytherapy was conducted for two common treatment procedures with two different post-implant dosimetry methods. The analysis was undertaken in order to determine the magnitude of D 90 uncertainty, how the magnitude of the uncertainty varied when D 90 was calculated using different dosimetry methods, and which factors were the major contributors to the uncertainty. The analysis considered the prostate as being homogeneous and tissue equivalent and made use of published data, as well as original data collected specifically for this analysis, and was performed according to the Guide to the expression of uncertainty in measurement (GUM). It was found that when prostate imaging and seed implantation were conducted in two separate sessions using only CT images for post-implant analysis, the expanded uncertainty in D 90 values were about 25 % at the 95 % confidence interval. When prostate imaging and seed implantation were conducted during a single session using CT and ultrasound images for post-implant analysis, the expanded uncertainty in D 90 values were about 33 %. Methods for reducing these uncertainty levels are discussed. It was found that variations in contouring the target tissue made the largest contribution to D 90 uncertainty, while the uncertainty in seed source strength made only a small contribution. It is important that clinicians appreciate the overall magnitude of D 90 uncertainty and understand the factors that affect it so that clinical decisions are soundly based, and resources are appropriately allocated. PMID:25555753

  14. Evaluation of in vivo low-dose mouse irradiation system

    NASA Astrophysics Data System (ADS)

    Noh, S. J.; Kim, H. J.; Kim, H.; Kye, Y.-U.; Kim, J. K.; Son, T. G.; Lee, M. W.; Jeong, D. H.; Yang, K. M.; Nam, S.-H.; Kang, Y.-R.

    2016-03-01

    This study aims to develop a facility that can irradiate subjects with a desired low dose, which can be used to assess the biological effects of low-dose radiation. We develop a single-occupancy mouse-cage and shelf system with adjustable geometric parameters, such as the distances and angles of the cages relative to the collimator. We assess the irradiation-level accuracy using two measurement methods. First, we calculate the angle and distance of each mouse cage relative to the irradiator. We employ a Monte Carlo n-particle simulation for all of the cages at a given distance from the radiation source to calculate the air kerma and the relative absorbed dose in the in-house designed shelving system; these are found to be approximately 0.108 and 0.109 Gy, respectively. Second, we measure the relative absorbed dose using glass dosimeters inserted directly into the heads and bodies of the mice. For a conventional irradiation system, the irradiation measurements show a maximum discrepancy of 42% between the absorbed and desired doses, whereas a discrepancy of only 6% from the desired dose is found for the designed mouse apartment system. In addition, multi-mouse cages are shown to yield to significantly greater differences in the mouse head and body relative absorbed doses, compared to the discrepancies found for single-occupancy cages in the conventional irradiation system. Our findings suggest that the in-house shelving system has greater reliability for the biological analysis of the effects of low-dose radiation.

  15. Harderian Gland Tumorigenesis: Low-Dose and LET Response.

    PubMed

    Chang, Polly Y; Cucinotta, Francis A; Bjornstad, Kathleen A; Bakke, James; Rosen, Chris J; Du, Nicholas; Fairchild, David G; Cacao, Eliedonna; Blakely, Eleanor A

    2016-05-01

    Increased cancer risk remains a primary concern for travel into deep space and may preclude manned missions to Mars due to large uncertainties that currently exist in estimating cancer risk from the spectrum of radiations found in space with the very limited available human epidemiological radiation-induced cancer data. Existing data on human risk of cancer from X-ray and gamma-ray exposure must be scaled to the many types and fluences of radiations found in space using radiation quality factors and dose-rate modification factors, and assuming linearity of response since the shapes of the dose responses at low doses below 100 mSv are unknown. The goal of this work was to reduce uncertainties in the relative biological effect (RBE) and linear energy transfer (LET) relationship for space-relevant doses of charged-particle radiation-induced carcinogenesis. The historical data from the studies of Fry et al. and Alpen et al. for Harderian gland (HG) tumors in the female CB6F1 strain of mouse represent the most complete set of experimental observations, including dose dependence, available on a specific radiation-induced tumor in an experimental animal using heavy ion beams that are found in the cosmic radiation spectrum. However, these data lack complete information on low-dose responses below 0.1 Gy, and for chronic low-dose-rate exposures, and there are gaps in the LET region between 25 and 190 keV/μm. In this study, we used the historical HG tumorigenesis data as reference, and obtained HG tumor data for 260 MeV/u silicon (LET ∼70 keV/μm) and 1,000 MeV/u titanium (LET ∼100 keV/μm) to fill existing gaps of data in this LET range to improve our understanding of the dose-response curve at low doses, to test for deviations from linearity and to provide RBE estimates. Animals were also exposed to five daily fractions of 0.026 or 0.052 Gy of 1,000 MeV/u titanium ions to simulate chronic exposure, and HG tumorigenesis from this fractionated study were compared to the

  16. Low Dose IR Creates an Oncogenic Microenvironment by Inducing Premature

    SciTech Connect

    Yuan, Zhi-Min

    2013-04-28

    Introduction Much of the work addressing ionizing radiation-induced cellular response has been carried out mainly with the traditional cell culture technique involving only one cell type, how cellular response to IR is influenced by the tissue microenvironment remains elusive. By use of a three-dimensional (3D) co-culture system to model critical interactions of different cell types with their neighbors and with their environment, we recently showed that low-dose IR-induced extracellular signaling via the tissue environment affects profoundly cellular responses. This proposal aims at determining the response of mammary epithelial cells in a tissue-like setting.

  17. Optimized source selection for intracavitary low dose rate brachytherapy

    SciTech Connect

    Nurushev, T.; Kim, Jinkoo

    2005-05-01

    A procedure has been developed for automating optimal selection of sources from an available inventory for the low dose rate brachytherapy, as a replacement for the conventional trial-and-error approach. The method of optimized constrained ratios was applied for clinical source selection for intracavitary Cs-137 implants using Varian BRACHYVISION software as initial interface. However, this method can be easily extended to another system with isodose scaling and shaping capabilities. Our procedure provides optimal source selection results independent of the user experience and in a short amount of time. This method also generates statistics on frequently requested ideal source strengths aiding in ordering of clinically relevant sources.

  18. Low-dose Computed Tomography in a Pregnant Woman with a Ruptured Pseudoaneurysm of the Abdominal Aorta.

    PubMed

    Ramac, Jelena Popić; Vidjak, Vinko; Skegro, Dinko; Duić, Zeljko; Blasković, Darko; Erdelez, Lidija; Skopljanac-Macina, Andrija; Suknaić, Slaven; Slavica, Marko; Leder, Nikola Ivan

    2015-09-01

    Imaging the pregnant patient presents a unique challenge to radiologist due to the risk of radiation to the conceptus (embryo/fetus). A rare case of a successfully recognized and treated pseudoaneurysm (PA) of the abdominal aorta is to be presented. The pseudoaneurysm occurred in the third trimester and had a favorable outcome for the mother and the baby. Emergent abdominal ultrasound (US) is the first modality in diagnostic algorithm for the rupture of aortic aneurysm in a pregnant woman. It provides the most rapid diagnostic information, although intestinal gas and abdominal tenderness may limit its accuracy. To confirm the findings, magnetic resonance angiography (MRA) or CT angiography (CTA) can be used. In our case, the diagnosis was established using a color Doppler ultrasonography of the abdomen and was later confirmed by a low dose CT scan of the abdominal aorta. MRA in such cases have some disadvantages. At many health centers, the monitoring of patients with acute ruptures is more difficult in the MR suite than at the CT scanner. MRA angiographic images are also subject to degradation by multiple artifacts and the visualization of the distal vasculature is suboptimal and inferior to the one done by CTA. Due to fetal movements, a small quantity of fresh blood can be overlooked by MR. MRA is often not available on a 24-hours basis, and the time required for making a diagnosis can preclude the use of MRA in an unstable patient. For this reason, we used a low dose CTA protocol to confirm the diagnosis. Low dose scanning protocols in CT can obtain sufficient diagnostic information while reducing the risk of radiation. A particular focus is put on the outline of new concepts for dose management and optimization. We used new approaches based on tube current modulation. The birth was induced by an urgent Caesarean section followed by a resection of a pseudoaneurysm and a reconstruction of the aorta with an end-to-end vascular prosthesis. PMID:26898082

  19. Quantifying tumour heterogeneity with CT

    PubMed Central

    Miles, Kenneth A.

    2013-01-01

    Abstract Heterogeneity is a key feature of malignancy associated with adverse tumour biology. Quantifying heterogeneity could provide a useful non-invasive imaging biomarker. Heterogeneity on computed tomography (CT) can be quantified using texture analysis which extracts spatial information from CT images (unenhanced, contrast-enhanced and derived images such as CT perfusion) that may not be perceptible to the naked eye. The main components of texture analysis can be categorized into image transformation and quantification. Image transformation filters the conventional image into its basic components (spatial, frequency, etc.) to produce derived subimages. Texture quantification techniques include structural-, model- (fractal dimensions), statistical- and frequency-based methods. The underlying tumour biology that CT texture analysis may reflect includes (but is not limited to) tumour hypoxia and angiogenesis. Emerging studies show that CT texture analysis has the potential to be a useful adjunct in clinical oncologic imaging, providing important information about tumour characterization, prognosis and treatment prediction and response. PMID:23545171

  20. Low doses of neutrons induce changes in gene expression

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, C.M. ); Panozzo, J.; Libertin, C.R. )

    1993-01-01

    Studies were designed to identify genes induced following low-dose neutron but not following [gamma]-ray exposure in fibroblasts. Our past work had shown differences in the expression of [beta]-protein kinase C and c-fos genes, both being induced following [gamma]-ray but not neutron exposure. We have identified two genes that are induced following neutron, but not [gamma]-ray, exposure: Rp-8 (a gene induced by apoptosis) and the long terminal repeat (LTR) of the human immunodeficiency (HIV). Rp-8 mRNA induction was demonstrated in Syrian hamster embryo fibroblasts and was found to be induced in cells exposed to neutrons administered at low (0.5 cGy/min) and at high dose rate (12 cGy/min). The induction of transcription from the LTR of HIV was demonstrated in HeLa cells bearing a transfected construct of the chloramphenicol acetyl transferase (CAT) gene driven by the HIV-LTR promoter. Measures of CAT activity and CAT transcripts following irradiation demonstrated an unresponsiveness to [gamma] rays over a broad range of doses. Twofold induction of the HIV-LTR was detected following neutron exposure (48 cGy) administered at low (0.5 cGy/min) but not high (12 cGy/min) dose rates. Ultraviolet-mediated HIV-LTR induction was inhibited by low-dose-rate neutron exposure.

  1. Low doses of neutrons induce changes in gene expression

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, C.M.; Panozzo, J.; Libertin, C.R.

    1993-06-01

    Studies were designed to identify genes induced following low-dose neutron but not following {gamma}-ray exposure in fibroblasts. Our past work had shown differences in the expression of {beta}-protein kinase C and c-fos genes, both being induced following {gamma}-ray but not neutron exposure. We have identified two genes that are induced following neutron, but not {gamma}-ray, exposure: Rp-8 (a gene induced by apoptosis) and the long terminal repeat (LTR) of the human immunodeficiency (HIV). Rp-8 mRNA induction was demonstrated in Syrian hamster embryo fibroblasts and was found to be induced in cells exposed to neutrons administered at low (0.5 cGy/min) and at high dose rate (12 cGy/min). The induction of transcription from the LTR of HIV was demonstrated in HeLa cells bearing a transfected construct of the chloramphenicol acetyl transferase (CAT) gene driven by the HIV-LTR promoter. Measures of CAT activity and CAT transcripts following irradiation demonstrated an unresponsiveness to {gamma} rays over a broad range of doses. Twofold induction of the HIV-LTR was detected following neutron exposure (48 cGy) administered at low (0.5 cGy/min) but not high (12 cGy/min) dose rates. Ultraviolet-mediated HIV-LTR induction was inhibited by low-dose-rate neutron exposure.

  2. Impairment of simulated motorcycle riding performance under low dose alcohol.

    PubMed

    Filtness, A J; Rudin-Brown, C M; Mulvihill, C M; Lenné, M G

    2013-01-01

    Crash statistics that include the blood alcohol concentration (BAC) of vehicle operators reveal that crash involved motorcyclists are over represented at low BACs (e.g., ≤0.05%). This riding simulator study compared riding performance and hazard response under three low dose alcohol conditions (sober, 0.02% BAC, 0.05% BAC). Forty participants (20 novice, 20 experienced) completed simulated rides in urban and rural scenarios while responding to a safety-critical peripheral detection task (PDT). Results showed a significant increase in the standard deviation of lateral position in the urban scenario and PDT reaction time in the rural scenario under 0.05% BAC compared with zero alcohol. Participants were most likely to collide with an unexpected pedestrian in the urban scenario at 0.02% BAC, with novice participants at a greater relative risk than experienced riders. Novices chose to ride faster than experienced participants in the rural scenario regardless of BAC. Not all results were significant, emphasising the complex situation of the effects of low dose BAC on riding performance, which needs further research. The results of this simulator study provide some support for a legal BAC for motorcyclists below 0.05%. PMID:22749316

  3. Low doses of cholestyramine in the treatment of hyperthyroidism.

    PubMed

    Kaykhaei, Mahmoud Ali; Shams, Mesbah; Sadegholvad, Abdosamad; Dabbaghmanesh, Mohammad Hossein; Omrani, Gholamhossein Ranjbar

    2008-01-01

    The enterohepatic circulation of thyroid hormones is increased in thyrotoxicosis. Bile-salt sequestrants bind thyroid hormones in the intestine and thereby increase their fecal excretion. Based on these observations, the use of cholestyramine has been tried. The present study evaluates the effect of low doses of cholestyramine as an adjunctive therapy in the management of hyperthyroidism. In a prospective, randomized, double-blind, placebo-controlled trial, 45 patients with newly diagnosed hyperthyroid Graves' disease were randomly assigned into the following treatment protocols: group I, cholestyramine 2 g BID, methimazole and propranolol; group II, cholestyramine 1 g BID, methimazole and propranolol; group III, placebo powder, methimazole and propranolol. The fixed dose of methimazole (30 mg/d) and propranolol (40 mg/d) was used. The study period was 4 weeks. Serum total triiodothyronine and free thyroxin were measured at baseline, and at the ends of the second and the fourth week of the study. The serum thyroid hormone levels decreased more rapidly and to a greater extent in the cholestyramine-treated groups. All of the patients in group I had achieved euthyroid state at the end of the study. We conclude that low dose of cholestyramine is an effective and well-tolerated adjunctive agent in the treatment of hyperthyroid Graves' disease. PMID:18946743

  4. Non linear processes modulated by low doses of radiation exposure

    NASA Astrophysics Data System (ADS)

    Mariotti, Luca; Ottolenghi, Andrea; Alloni, Daniele; Babini, Gabriele; Morini, Jacopo; Baiocco, Giorgio

    The perturbation induced by radiation impinging on biological targets can stimulate the activation of several different pathways, spanning from the DNA damage processing to intra/extra -cellular signalling. In the mechanistic investigation of radiobiological damage this complex “system” response (e.g. omics, signalling networks, micro-environmental modifications, etc.) has to be taken into account, shifting from a focus on the DNA molecule solely to a systemic/collective view. An additional complication comes from the finding that the individual response of each of the involved processes is often not linear as a function of the dose. In this context, a systems biology approach to investigate the effects of low dose irradiations on intra/extra-cellular signalling will be presented, where low doses of radiation act as a mild perturbation of a robustly interconnected network. Results obtained through a multi-level investigation of both DNA damage repair processes (e.g. gamma-H2AX response) and of the activation kinetics for intra/extra cellular signalling pathways (e.g. NFkB activation) show that the overall cell response is dominated by non-linear processes - such as negative feedbacks - leading to possible non equilibrium steady states and to a poor signal-to-noise ratio. Together with experimental data of radiation perturbed pathways, different modelling approaches will be also discussed.

  5. Thermoluminescent dosimeters for low dose X-ray measurements.

    PubMed

    Fernández, S Del Sol; García-Salcedo, R; Sánchez-Guzmán, D; Ramírez-Rodríguez, G; Gaona, E; de León-Alfaro, M A; Rivera-Montalvo, T

    2016-01-01

    The response of TLD-100, CaSO4:Dy and LiF:Mg,Cu,P for a range of X-ray low dose was measured. For calibration, the TLDs were arranged at the center of the X-ray field. The dose output of the X-ray machine was determined using an ACCU-Gold. All dosimeters were exposed at the available air kerma values of 14.69 mGy within a field 10×10 cm(2) at 80 cm of SSD. Results of LiF:Mg,Cu,P X-ray irradiated showed 4.8 times higher sensitivity than TLD-100. Meanwhile, TL response of CaSO4:Dy exposed at the same dose was 5.6 time higher than TLD-100. Experimental results show for low dose X-ray measurements a better linearity for LiF:Mg,Cu,P compared with that of TLD-100. CaSO4:Dy showed a linearity from 0.1 to 60 mGy. PMID:26609683

  6. The Effects of ELDRS at Ultra-Low Dose Rates

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; Forney, James; Carts, Martin; Phan, Anthony; Pease, Ronald; Kruckmeyer, Kirby; Cox, Stephen; LaBel, Kenneth; Burns, Samuel; Albarian, Rafi; Holcombe, Bruce; Little, Bradley; Salzman, James; Chaumont, Geraldine; Duperray, Herve; Ouellet, Al

    2011-01-01

    We present results on the effects on ELDRS at dose rates of 10, 5, 1, and 0.5 mrad(Si)/s for a variety of radiation hardened and commercial devices. We observed low dose rate enhancement below 10 mrad(Si)/s in several different parts. The magnitudes of the dose rate effects vary. The TL750L, a commercial voltage regulator, showed dose rate dependence in the functional failures, with initial failures occurring after 10 krad(Si) for the parts irradiated at 0.5 mrad(Si)/s. The RH1021 showed an increase in low dose rate enhancement by 2x at 5 mrad(Si)/s relative to 8 mrad(Si)/s and high dose rate, and parametric failure after 100 krad(Si). Additionally the ELDRS-free devices, such as the LM158 and LM117, showed evidence of dose rate sensitivity in parametric degradations. Several other parts also displayed dose rate enhancement, with relatively lower degradations up to approx.15 to 20 krad(Si). The magnitudes of the dose rate enhancement will likely increase in significance at higher total dose levels.

  7. 'Low-dose' corticosteroid prophylaxis against fat embolism.

    PubMed

    Kallenbach, J; Lewis, M; Zaltzman, M; Feldman, C; Orford, A; Zwi, S

    1987-10-01

    The effect of 'low-dose' corticosteroids (9 mg/kg methylprednisolone), given after skeletal trauma, on the incidence of the fat embolism syndrome and isolated arterial hypoxemia was studied in 42 controls and 40 steroid-treated subjects. Fat embolism occurred in ten controls (23.8%) and one steroid-treated subject (2.5%) (p = 0.01). A further 44 subjects developed isolated hypoxemia. This was severe (PaO2 less than 50 mm Hg) in seven of 32 controls (21.9%) and one of 39 steroid-treated subjects (2.6%) (p = 0.01). The overall incidence of hypoxemia was 67.1%, affecting 33 controls (78.6%) and 22 steroid-treated patients (55%) (p less than 0.05). The degree of hypoxemia was severe (PaO2 less than 50 mm Hg) in 12 controls (28.6%) and two (5%) of the steroid-treated subjects (p = 0.005). No control subject died or required mechanical ventilation. One steroid-treated subject without fat embolism died of a fulminant infection. Although methylprednisolone in a relatively low dose provides protection against fat embolism and pulmonary dysfunction after skeletal trauma, the safety of this therapy requires further evaluation. PMID:3312625

  8. A New Era of Low-Dose Radiation Epidemiology.

    PubMed

    Kitahara, Cari M; Linet, Martha S; Rajaraman, Preetha; Ntowe, Estelle; Berrington de González, Amy

    2015-09-01

    The last decade has introduced a new era of epidemiologic studies of low-dose radiation facilitated by electronic record linkage and pooling of cohorts that allow for more direct and powerful assessments of cancer and other stochastic effects at doses below 100 mGy. Such studies have provided additional evidence regarding the risks of cancer, particularly leukemia, associated with lower-dose radiation exposures from medical, environmental, and occupational radiation sources, and have questioned the previous findings with regard to possible thresholds for cardiovascular disease and cataracts. Integrated analysis of next generation genomic and epigenetic sequencing of germline and somatic tissues could soon propel our understanding further regarding disease risk thresholds, radiosensitivity of population subgroups and individuals, and the mechanisms of radiation carcinogenesis. These advances in low-dose radiation epidemiology are critical to our understanding of chronic disease risks from the burgeoning use of newer and emerging medical imaging technologies, and the continued potential threat of nuclear power plant accidents or other radiological emergencies. PMID:26231501

  9. Low dose cyclophosphamide: Mechanisms of T cell modulation.

    PubMed

    Madondo, Mutsa Tatenda; Quinn, Michael; Plebanski, Magdalena

    2016-01-01

    Cyclophosphamide is considered one of the most successful chemotherapy drugs and is listed on the World Health Organisations List of Essential Medicines. Since its initial synthesis in 1958, it has been widely used to treat a range of cancers but its use has been declining due to the advent of platinum based and other chemotherapy agents. However, cyclophosphamide is still used either as a single agent or as adjuvant therapy to treat lymphomas, and breast and ovarian cancers at much lower doses. The efficacy of low dose cyclophosphamide is primarily due to its ability to promote anti-tumour immunity, by selectively depleting regulatory T cells and enhancing effector T cell function. Compared to effecter T cells, regulatory T cells have metabolic adaptations that make them more susceptible to cyclophosphamide-mediated cytotoxicity. In this review, we highlight the potential for improving the efficacy of low dose cyclophosphamide by combining insights on the mechanisms of cyclophosphamide-mediated cytotoxicity, and how these cytotoxic effects of cyclophosphamide influence T cell function, thereby contributing to anti-tumour immunity. PMID:26620820

  10. Low dose scatter correction for digital chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Inscoe, Christina R.; Wu, Gongting; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2015-03-01

    Digital chest tomosynthesis (DCT) provides superior image quality and depth information for thoracic imaging at relatively low dose, though the presence of strong photon scatter degrades the image quality. In most chest radiography, anti-scatter grids are used. However, the grid also blocks a large fraction of the primary beam photons requiring a significantly higher imaging dose for patients. Previously, we have proposed an efficient low dose scatter correction technique using a primary beam sampling apparatus. We implemented the technique in stationary digital breast tomosynthesis, and found the method to be efficient in correcting patient-specific scatter with only 3% increase in dose. In this paper we reported the feasibility study of applying the same technique to chest tomosynthesis. This investigation was performed utilizing phantom and cadaver subjects. The method involves an initial tomosynthesis scan of the object. A lead plate with an array of holes, or primary sampling apparatus (PSA), was placed above the object. A second tomosynthesis scan was performed to measure the primary (scatter-free) transmission. This PSA data was used with the full-field projections to compute the scatter, which was then interpolated to full-field scatter maps unique to each projection angle. Full-field projection images were scatter corrected prior to reconstruction. Projections and reconstruction slices were evaluated and the correction method was found to be effective at improving image quality and practical for clinical implementation.

  11. Low-dose aspirin as treatment for central serous chorioretinopathy

    PubMed Central

    Caccavale, Antonio; Romanazzi, Filippo; Imparato, Manuela; Negri, Angelo; Morano, Anna; Ferentini, Fabio

    2010-01-01

    Purpose: To evaluate the effectiveness of low-dose aspirin for the treatment of central serous chorioretinopathy (CSCR). Patients and methods: Patients with classical or multifocal CSCR were treated with aspirin 100 mg per day orally for 1 month followed by 100 mg on alternate days for 5 months. Treated patients were compared with historic controls consisting of patients with classical or multifocal CSCR previously followed up at our institution. Results: Mean visual acuity in the group treated with aspirin started to improve after the first week of therapy and continued to improve throughout the following 3 months. Visual recovery was slower in the untreated control group than in the treated group and achieved better visual acuity between the first and third month from the onset of the disease. There were no adverse events related to the administration of aspirin. Conclusion: The results indicate that treatment with low-dose aspirin may result in more rapid visual rehabilitation with fewer recurrences in patient with CSCR compared with untreated historic controls. The effectiveness of treatment with aspirin supports our hypothesis regarding the role of impaired fibrinolysis and increased platelet aggregation in the choriocapillaris in the pathogenesis of CSCR. PMID:20714368

  12. [Phantom Study on Dose Reduction Using Iterative Reconstruction in Low-dose Computed Tomography for Lung Cancer Screening].

    PubMed

    Minehiro, Kaori; Takata, Tadanori; Hayashi, Hiroyuki; Sakuda, Keita; Nunome, Haruka; Kawashima, Hiroko; Sanada, Shigeru

    2015-12-01

    We investigated dose reduction ability of an iterative reconstruction technology for low-dose computed tomography (CT) for lung cancer screening. The Sinogram Affirmed Iterative Reconstruction (SAFIRE) provided in a multi slice CT system, Somatom Definition Flash (Siemens Healthcare) was used. An anthropomorphic chest phantom (N-1, Kyoto Kagaku) was scanned at volume CT dose index (CTDIvol) of 0.50-11.86 mGy with 120 kV. For noise (standard deviation) and contrast-to-noise ratio (CNR) measurements, CTP486 and CTP515 modules in the Catphan (The Phantom Laboratory) were scanned. Radiological technologists were participated in the perceptual comparison. SAFIRE reduced the SD values by approximately 50% compared with filter back projection (FBP). The estimated dose reduction rates by SAFIRE determined from the perceptual comparison was approximately 23%, while 75% dose reduction rate was expected from the SD value reduction of 50%. PMID:26685831

  13. Synergistic effect of low-dose cucurbitacin B and low-dose methotrexate for treatment of human osteosarcoma

    PubMed Central

    Goff, Catherine; Iwanski, Gabriela B.; Forscher, Charles; Doan, Ngan B.; Said, Jonathan W.; Koeffler, H. Phillip

    2016-01-01

    We investigated the use of cucurbitacin B, a plant-derived tetracyclic triterpenoid, as a single agent or in combination with methotrexate (MTX) for human osteosarcoma (OS) treatment. Cucurbitacin B showed antiproliferative activity against seven human OS cell lines in vitro accompanying G2/M cell cycle arrest, apoptosis, and inhibition of ERK, Akt, and mTOR proteins. Cucurbitacin B in combination with MTX synergistically inhibited OS cell growth in vitro. Low-dose cucurbitacin B (LD-CuB, 0.5 mg/kg body weight) or low-dose MTX (LD-MTX, 150 mg/kg) failed to decrease the size of human OS xenografts in nude mice. However, combined therapy at identical concentrations inhibited tumor growth by 62% vs. LD-CuB and 81% vs. LD-MTX (p < 0.001). Strikingly, the effect persisted even when the dose of MTX was decreased by two thirds (VLD-MTX, 50 mg/kg). In conclusion, cucurbitacin B alone or in combination with MTX shows promising antiproliferative activity against human OS. PMID:21440986

  14. Low-Dose Radioactive Iodine Destroys Thyroid Tissue Left After Surgery

    MedlinePlus

    ... of Endocrine & Neuroendocrine Neoplasias Research Low-Dose Radioactive Iodine Destroys Thyroid Tissue Left after Surgery Adapted from ... NCI Cancer Bulletin . A low dose of radioactive iodine given after surgery for thyroid cancer destroyed (ablated) ...

  15. [Early lung cancer detection in an occupational asbestos exposed population: clinical impact of low-dose computed tomography screening].

    PubMed

    Pira, E; Coggiola, M; Bosio, D

    2010-01-01

    Lung cancer is the primary cause of cancer mortality in developed countries. Early detection and surgical resection is essential for the treatment of lung cancer. The introduction of low-dose spiral computed tomography (LDCT) is considered one of the most promising clinical research developments in early diagnosis of lung cancer. Our study is aimed at the evaluation of spiral CT in a cohort of subjects with a past occupational exposure to asbestos at high risk of developing lung cancer. 149 subjects were enrolled between 2007 and 2009 (the criteria for enrollment were date of birth between 1930-1961, no previous cancer and general good health, latency from the beginning of exposure > 10 years, exposure duration > 1 year, possibility to undergo to surgery). A helical low-dose CT (LDCT) of the chest was performed yearly and an evaluation protocol derived from IEO with a morphological analysis of nodules have been adopted. 13 nodules were diagnosed in the first CT, 7 in the second and 3 in the third but no invasive procedures have been taken and no lung cancer have been detected. Our early follow-up data aren't able yet to evaluate the effect of screening with LDCT on mortality but have do not confirm some of the literature initial results such as the Increase in cases of overdiagnosis (false positive) due to the high prevalence of benign lesions. PMID:21438306

  16. Optical fiber sensor for low dose gamma irradiation monitoring

    NASA Astrophysics Data System (ADS)

    de Andrés, Ana I.; Esteban, Ã.`scar; Embid, Miguel

    2016-05-01

    An optical fiber gamma ray detector is presented in this work. It is based on a Terbium doped Gadolinium Oxysulfide (Gd2O2S:Tb) scintillating powder which cover a chemically etched polymer fiber tip. This etching improves the fluorescence gathering by the optical fiber. The final diameter has been selected to fulfill the trade-off between light gathering and mechanical strength. Powder has been encapsulated inside a microtube where the fiber tip is immersed. The sensor has been irradiated with different air Kerma doses up to 2 Gy/h with a 137Cs source, and the spectral distribution of the fluorescence intensity has been recorded in a commercial grade CCD spectrometer. The obtained signal-to-noise ratio is good enough even for low doses, which has allowed to reduce the integration time in the spectrometer. The presented results show the feasibility for using low cost equipment to detect/measure ionizing radiation as gamma rays are.

  17. Low-dose aripiprazole for refractory burning mouth syndrome.

    PubMed

    Umezaki, Yojiro; Takenoshita, Miho; Toyofuku, Akira

    2016-01-01

    We report a case of refractory burning mouth syndrome (BMS) ameliorated with low dose of aripiprazole. The patient was a 66-year-old female who had suffered from chronic burning pain in her tongue for 13 months. No abnormality associated with the burning sensation was detected in the laboratory tests and the oral findings. Considering the clinical feature and the history together, we diagnosed the burning sensation as BMS. The BMS pain was decreased by aripiprazole (powder) 1.0 mg/d, though no other antidepressants had satisfying pain relief. It could be supposed that the efficacy of aripiprazole is caused by dopamine stabilization in this case, and BMS might have a subtype that is reactive to aripiprazole. Further studies are needed to confirm the efficacy of aripiprazole for BMS. PMID:27279742

  18. Low-dose digital computed radiography in pediatric chest imaging

    SciTech Connect

    Kogutt, M.S.; Jones, J.P.; Perkins, D.D.

    1988-10-01

    A prototype digital computed radiographic imaging system that uses laser-stimulated luminescence was evaluated for its ability to achieve reproducible, high-detail, low-dose pediatric chest radiographs. Using this system, we performed a total of 401 examinations in infants and children, and achieved an 85% reduction in radiation dose, as compared with that delivered when film-screen techniques were used. We also achieved satisfactory image resolution, and the images obtained were of acceptable diagnostic quality. A direct comparison of analog and digital radiographs showed that comparable quality and clinical acceptability could be readily maintained between the two techniques. This study shows that high-quality images can be produced by this system at radiation doses reduced by 85% when compared with doses from standard radiographic techniques.

  19. [Low dose ketamine for pediatric procedure-related pain].

    PubMed

    Annequin, D

    2012-07-01

    For painful procedures in children, national recommendations are now available in France. When sedation-analgesia with nitrous oxide/oxygen mixture fails, in order to perform a painful procedure under good conditions, low dose ketamine (IV bolus titration 0.5 mg/kg but not more than 2 mg/kg) is the only drug potentially used by a trained physician, without the presence of an anaesthesiologist (Grade A). With these dosages without drug combination, the highest level of security depends largely on the quality of the hospital environment (Grade A). Intramuscular (<4 mg/kg) is an alternative route, but the recovery time is delayed (Grade B). The optimal management is performed by an anesthesiologist, it is necessary to facilitate access to the operating room for children undergoing this type of procedure (Professional consensus). Mainly IV ketamine can be used by pediatric intensive care and emergency physicians who currently have medical skills to detect and treat side effects. PMID:22595625

  20. Hereditary hemorrhagic telangiectasia treated with low dose intravenous bevacizumab

    PubMed Central

    Wee, Jee Wan; Jeon, Young Woo; Eun, Jun Young; Kim, Han Jo; Bae, Sang Byung

    2014-01-01

    Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder that leads to mucocutaneous telangiectasias, epistaxis, and gastrointestinal bleeding. Depending on the severity and manifestation of the disease, various therapeutic modalities have been used, from local bleeding control to surgery or concomitant drug therapy. Several articles under review have presented guidelines for treatment of HHT with bevacizumab as a direct anti-angiogenesis strategy. Still, neither the exact optimal dose nor the minimum effective dose of intravenous bevacizumab in patients with severe HHT has been reported. A 55-year-old man presented with long-standing epistaxis, recent melena, dizziness, and a three-generation family history of chronic epistaxis, anemia, and regular blood transfusions. Treatment with argon plasma coagulation (APC) for the gastrointestinal bleeding failed to raise hemoglobin levels, we considered using the bevacizumab. We report a patient with severe HHT, who was treated with low-dose bevacizumab (2 mg/kg) and improved substantially. PMID:25325040

  1. Radiobiological evaluation of low dose-rate prostate brachytherapy implants

    NASA Astrophysics Data System (ADS)

    Knaup, Courtney James

    Low dose-rate brachytherapy is a radiation therapy treatment for men with prostate cancer. While this treatment is common, the use of isotopes with varying dosimetric characteristics means that the prescription level and normal organ tolerances vary. Additionally, factors such as prostate edema, seed loss and seed migration may alter the dose distribution within the prostate. The goal of this work is to develop a radiobiological response tool based on spatial dose information which may be used to aid in treatment planning, post-implant evaluation and determination of the effects of prostate edema and seed migration. Aim 1: Evaluation of post-implant prostate edema and its dosimetric and biological effects. Aim 2: Incorporation of biological response to simplify post-implant evaluation. Aim 3: Incorporation of biological response to simplify treatment plan comparison. Aim 4: Radiobiologically based comparison of single and dual-isotope implants. Aim 5: Determine the dosimetric and radiobiological effects of seed disappearance and migration.

  2. Quantifying exploratory low dose compounds in humans with AMS

    PubMed Central

    Dueker, Stephen R.; Vuong, Le T.; Lohstroh, Peter N.; Giacomo, Jason A.; Vogel, John S.

    2010-01-01

    Accelerator Mass Spectrometry is an established technology whose essentiality extends beyond simply a better detector for radiolabeled molecules. Attomole sensitivity reduces radioisotope exposures in clinical subjects to the point that no population need be excluded from clinical study. Insights in human physiochemistry are enabled by the quantitative recovery of simplified AMS processes that provide biological concentrations of all labeled metabolites and total compound related material at non-saturating levels. In this paper, we review some of the exploratory applications of AMS 14C in toxicological, nutritional, and pharmacological research. This body of research addresses the human physiochemistry of important compounds in their own right, but also serves as examples of the analytical methods and clinical practices that are available for studying low dose physiochemistry of candidate therapeutic compounds, helping to broaden the knowledge base of AMS application in pharmaceutical research. PMID:21047543

  3. Extrapyramidal side effects with low doses of amisulpride

    PubMed Central

    Mandal, Nikhiles; Singh, Om P.; Sen, Subrata

    2014-01-01

    Amisulpride, the newly introduced antipsychotic in India, is claimed to be effective in both positive and negative symptom schizophrenia and related disorders, though it has little or no action on serotonergic receptors. Limbic selectivity and lower striatal dopaminergic receptor binding capacity causes very low incidence of EPS. But, in clinical practice, we are getting EPS with this drug even at lower doses. We have reported three cases of akathisia, acute dystonia, and drug-induced Parkinsonism with low doses of amisulpride. So, we should keep this side effect in mind when using amisulpride. In fact, more studies are required in our country to find out the incidence of EPS and other associated mechanism. PMID:24891713

  4. Surrogates of protection in repeated low-dose challenge experiments.

    PubMed

    Long, Dustin M; Hudgens, Michael G; Wu, Chih-Da

    2015-05-10

    A critical step toward developing a successful vaccine to control the human immunodeficiency virus pandemic entails evaluation of vaccine candidates in non-human primates (NHPs). Historically, these studies have usually entailed challenges (i.e., exposures) with very high doses of a simian version of human immunodeficiency virus, resulting in infection of all NHPs in the experiment after a single challenge. More recently, researchers have begun to conduct repeated low-dose challenge (RLC) studies in NHPs that are believed to more closely mimic typical exposure in natural human transmission settings. One objective of RLC studies is to assess whether measured immune responses to vaccination can serve as surrogate endpoints for the primary endpoint of interest, namely infection. In this paper, different designs of RLC studies for assessing a binary surrogate of protection are considered. PMID:25628249

  5. Surrogates of Protection in Repeated Low-Dose Challenge Experiments

    PubMed Central

    Long, Dustin M.; Hudgens, Michael G.; Wu, Chih-Da

    2015-01-01

    A critical step toward developing a successful vaccine to control the human immunodeficiency virus (HIV) pandemic entails evaluation of vaccine candidates in non-human primates (NHPs). Historically, these studies have usually entailed challenges (i.e., exposures) with very high doses of a simian version of HIV, resulting in infection of all NHPs in the experiment after a single challenge. More recently, researchers have begun to conduct repeated low-dose challenge (RLC) studies in NHPs that are believed to more closely mimic typical exposure in natural human transmission settings. One objective of RLC studies is to assess whether measured immune responses to vaccination can serve as surrogate endpoints for the primary endpoint of interest, namely infection. In this paper, different designs of RLC studies for assessing a binary surrogate of protection are considered. PMID:25628249

  6. Low-dose aripiprazole for refractory burning mouth syndrome

    PubMed Central

    Umezaki, Yojiro; Takenoshita, Miho; Toyofuku, Akira

    2016-01-01

    We report a case of refractory burning mouth syndrome (BMS) ameliorated with low dose of aripiprazole. The patient was a 66-year-old female who had suffered from chronic burning pain in her tongue for 13 months. No abnormality associated with the burning sensation was detected in the laboratory tests and the oral findings. Considering the clinical feature and the history together, we diagnosed the burning sensation as BMS. The BMS pain was decreased by aripiprazole (powder) 1.0 mg/d, though no other antidepressants had satisfying pain relief. It could be supposed that the efficacy of aripiprazole is caused by dopamine stabilization in this case, and BMS might have a subtype that is reactive to aripiprazole. Further studies are needed to confirm the efficacy of aripiprazole for BMS. PMID:27279742

  7. Abnormal thallium 201 scintigraphy during low-dose vasopressin infusions

    SciTech Connect

    Davison, R.; Kaplan, K.; Bines, A.; Spies, S.; Reed, M.T.; Lesch, M.

    1986-12-01

    Thallium 201 (/sup 201/Tl) myocardial scans were obtained in 16 patients just prior to the discontinuation of a vasopressin infusion (.1 to .2 units/min) administered for the treatment of upper gastrointestinal bleeding. Repeat scintigraphy was performed two to three hours after the vasopressin was stopped. Eleven of the 16 patients (69 percent) demonstrated areas of decreased myocardial /sup 201/Tl uptake that resolved after the infusion was stopped. Heart rate-blood pressure product was significantly lower at the time of the second scan. Autopsies were secured in three of 11 scan-positive patients: one had severe coronary artery obstruction, one nonsignificant disease, and another had normal coronary arteries. Vasopressin, even at low doses, can induce abnormalities in myocardial perfusion that are probably mediated by a direct effect on the coronary circulation. They are usually not detectable by routine monitoring techniques and conceivably form the basis for the cardiovascular morbidity associated with the use of this agent.

  8. Personalized body segment parameters from biplanar low-dose radiography.

    PubMed

    Dumas, Raphaël; Aissaoui, Rachid; Mitton, David; Skalli, Wafa; de Guise, Jacques A

    2005-10-01

    Body segment parameters are essential data in biomechanics. They are usually computed with population-specific predictive equations from literature. Recently, medical imaging and video-based methods were also reported for personalized computation. However, these methods present limitations: some of them provide only two-dimensional measurements or external measurements, others require a lot of tomographic images for a three-dimensional (3-D) reconstruction. Therefore, an original method is proposed to compute personalized body segment parameters from biplanar radiography. Simultaneous low-dose frontal and sagittal radiographs were obtained with EOS system. The upper leg segments of eight young males and eight young females were studied. The personalized parameters computed from the biplanar radiographic 3-D reconstructions were compared to literature. The biplanar radiographic method was consistent with predictive equations based on gamma-ray scan and dual energy X-ray absorptiometry. PMID:16235661

  9. The spectrum of mutation produced by low dose radiation

    SciTech Connect

    Morley,Alexander,A; Turner, David,R

    2004-10-31

    Inherited mutations are the basis of evolution and acquired mutations in humans are important in ageing, cancer and possibly various forms of tissue degeneration. Mutations are responsible for many of the long-term effects of radiation. However, sensitive direct detection of mutations in humans has been difficult. The aims of the project were to develop methods for the sensitive enumeration of mutations in DNA, to measure mutation frequencies in a wide variety of tissue types and to quantify the mutational effect of direct oxidative damage produced by radiation, at both high and low doses. The project was successful in developing a sensitive method which could detect mutations directly in the genetic material, DNA at a sensitivity of 1 mutated molecule in 1000000000 unmutated molecules. However a number of methodological problems had to be overcome and lack of ongoing funding made it impossible to fulfill all of the aims of the project

  10. Restless Legs Syndrome After Single Low Dose Quetiapine Administration.

    PubMed

    Soyata, Ahmet Z; Celebi, Fahri; Yargc, Lutfi I

    2016-01-01

    Restless legs syndrome is an underdiagnosed sensori-motor disorder and psychotropic drugs are one of the main secondary causes of the illness. The most common psychotropic agents that cause restless legs syndrome are antidepressants; however, antipsychotics have also been reported to induce restless legs syndrome. The prevalence, vulnerability factors and the underlying mechanism of antipsychotic-induced restless legs syndrome are unclear. A possible explanation is that dopaminergic blockade is the main precipitator of the syndrome. Quetiapine-induced restless legs syndrome is another point of interest because of its low binding to D2 receptors. We herein report the case of a restless legs syndrome that emerged after a single low dose quetiapine administration. PMID:26582164

  11. Low-dose radiation: a cause of breast cancer

    SciTech Connect

    Land, C.E.

    1980-08-15

    It is likely that the breast is the organ most sensitive to radiation carcinogenesis in postpubertal women. Studies of different exposed populations have yielded remarkably consistent results, in spite of wide differences in underlying breast cancer rates and conditions of exposure. Excess risk is approximately proportional to dose, and is relatively independent of ionization density and fractionization of dose. This implies that the risk associated with low-dose exposures to ionizing radiation can be estimated with some confidence from higher-dose data. Excess risk is heavily dependent on age at exposure but relatively independent of population differences in normal risk. The temporal patterns after exposure of both radiation-induced and naturally occurring breast cancer are similar, suggesting a strong influence of factors other than radiation on radiation-induced breast cancer. Uncertainties remain about risks from exposures before puberty and after menopause.

  12. Low dose mTHPC photodynamic therapy for cholangiocarcinoma

    NASA Astrophysics Data System (ADS)

    Stepp, Herbert; Kniebühler, Gesa; Pongratz, Thomas; Betz, Christian S.; Göke, Burkhard; Sroka, Ronald; Schirra, Jörg

    2013-06-01

    Objective: Demonstration of whether a low dose of mTHPC (temoporfin , Foscan) is sufficient to induce an efficient clinical response in palliative PDT of non-resectable cholangiocarcinoma (CC), while showing a low side effect profile as compared to the standard Photofrin PDT. Materials and Methods: 13 patients (14 treatment sessions) with non-resectable CC were treated with stenting and PDT (3 mg Foscan per treatment, 0.032-0.063 mg/kg body weight, 652 nm, 50 J/cm). Fluorescence measurements were performed with a single bare fiber for 5/13 patients prior to PDT at the tumor site to determine the fluorescence contrast. For another 7/13 patients, long-term fluorescence-kinetics were measured on the oral mucosa to determine the time of maximal relative fluorescence intensity. Results: Foscan fluorescence could clearly be identified spectroscopically as early as 20 hours after administration. It was not significantly different between lesion and normal tissue within the bile duct. Fluorescence kinetics assessed at the oral mucosa were highest at 72-96 hours after administration. The DLI was therefore extended from 20 hours to approx. 70 hours for the last 5 patients treated. The treatment effect was promising with a median survival of 11 months for the higher grade tumors (Bismuth types III and IV). Local side effects occurred in one patient (pancreatitis), systemic side effects were much reduced compared to prior experience with Photofrin. Conclusion: Combined stenting and photodynamic therapy (PDT) performed with a low dose of Foscan results in comparable survival times relative to standard Photofrin PDT, while lowering the risk of side effects significantly.

  13. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    DOE PAGESBeta

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; et al

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initiallymore » improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.« less

  14. Cardiovascular risks associated with low dose ionizing particle radiation.

    PubMed

    Yan, Xinhua; Sasi, Sharath P; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton ((1)H; 0.5 Gy, 1 GeV) and iron ion ((56)Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in (56)Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, (56)Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy. PMID:25337914

  15. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    SciTech Connect

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.

  16. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    PubMed Central

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy. PMID:25337914

  17. Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

    SciTech Connect

    Kleiman, Norman Jay

    2013-11-30

    The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

  18. Migration of a strand of four seeds in low-dose-rate brachytherapy

    PubMed Central

    Dedic-Hagan, Jasmina; Teh, Amy Y M; Liang, Eisen; Collett, Nicholas; Woo, Henry H

    2014-01-01

    We report a case of stranded-seed migration (one strand of four seeds), via the prostatic venous plexus to the internal pudendal vein, in low-dose-rate (LDR) prostate brachytherapy. A 70-year-old man with low-risk prostate adenocarcinoma underwent transperineal permanent seed implantation. A total of 93 iodine-125 seeds were implanted (91 stranded seeds and 2 loose seeds). Immediate postimplantation fluoroscopic image and day 1 postimplantation CT scan indicated all implanted seeds to be within the vicinity of the prostate as planned. Day 30 pelvic X-ray and CT scan revealed migration of a strand of four seeds to the right pelvis (adjacent to ischial spine). At 2 years postimplantation, the patient continues to have good disease control with prostate specific antigen level of 0.69 μg/L, and asymptomatic. To the best of our knowledge, this is the first report of migration of an entire strand of seeds following LDR prostate brachytherapy. PMID:24879735

  19. The Contribution of Tissue Level Organization to Genomic Stability Following Low Dose/Low Dose Rate Gamma and Proton Irradiation

    SciTech Connect

    Cheryl G. Burrell, Ph.D.

    2012-05-14

    The formation of functional tissue units is necessary in maintaining homeostasis within living systems, with individual cells contributing to these functional units through their three-dimensional organization with integrin and adhesion proteins to form a complex extra-cellular matrix (ECM). This is of particular importance in those tissues susceptible to radiation-induced tumor formation, such as epithelial glands. The assembly of epithelial cells of the thyroid is critical to their normal receipt of, and response to, incoming signals. Traditional tissue culture and live animals present significant challenges to radiation exposure and continuous sampling, however, the production of bioreactor-engineered tissues aims to bridge this gap by improve capabilities in continuous sampling from the same functional tissue, thereby increasing the ability to extrapolate changes induced by radiation to animals and humans in vivo. Our study proposes that the level of tissue organization will affect the induction and persistence of low dose radiation-induced genomic instability. Rat thyroid cells, grown in vitro as 3D tissue analogs in bioreactors and as 2D flask grown cultures were exposed to acute low dose (1, 5, 10 and 200 cGy) gamma rays. To assess immediate (6 hours) and delayed (up to 30 days) responses post-irradiation, various biological endpoints were studied including cytogenetic analyses, apoptosis analysis and cell viability/cytotoxicity analyses. Data assessing caspase 3/7 activity levels show that, this activity varies with time post radiation and that, overall, 3D cultures display more genomic instability (as shown by the lower levels of apoptosis over time) when compared to the 2D cultures. Variation in cell viability levels were only observed at the intermediate and late time points post radiation. Extensive analysis of chromosomal aberrations will give further insight on the whether the level of tissue organization influences genomic instability patterns after

  20. Simulated Microgravity and Low-Dose/Low-Dose-Rate Radiation Induces Oxidative Damage in the Mouse Brain.

    PubMed

    Mao, Xiao Wen; Nishiyama, Nina C; Pecaut, Michael J; Campbell-Beachler, Mary; Gifford, Peter; Haynes, Kristine E; Becronis, Caroline; Gridley, Daila S

    2016-06-01

    Microgravity and radiation are stressors unique to the spaceflight environment that can have an impact on the central nervous system (CNS). These stressors could potentially lead to significant health risks to astronauts, both acutely during the course of a mission or chronically, leading to long-term, post-mission decrements in quality of life. The CNS is sensitive to oxidative injury due to high concentrations of oxidizable, unsaturated lipids and low levels of antioxidant defenses. The purpose of this study was to evaluate oxidative damage in the brain cortex and hippocampus in a ground-based model for spaceflight, which includes prolonged unloading and low-dose radiation. Whole-body low-dose/low-dose-rate (LDR) gamma radiation using (57)Co plates (0.04 Gy at 0.01 cGy/h) was delivered to 6 months old, mature, female C57BL/6 mice (n = 4-6/group) to simulate the radiation component. Anti-orthostatic tail suspension was used to model the unloading, fluid shift and physiological stress aspects of the microgravity component. Mice were hindlimb suspended and/or irradiated for 21 days. Brains were isolated 7 days or 9 months after irradiation and hindlimb unloading (HLU) for characterization of oxidative stress markers and microvessel changes. The level of 4-hydroxynonenal (4-HNE) protein, an oxidative specific marker for lipid peroxidation, was significantly elevated in the cortex and hippocampus after LDR + HLU compared to controls (P < 0.05). The combination group also had the highest level of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) expression compared to controls (P < 0.05). There was a significant decrease in superoxide dismutase (SOD) expression in the animals that received HLU only or combined LDR + HLU compared to control (P < 0.05). In addition, 9 months after LDR and HLU exposure, microvessel densities were the lowest in the combination group, compared to age-matched controls in the cortex (P < 0.05). Our data provide the first evidence

  1. Evaluation of low-dose limits in 3D-2D rigid registration for surgical guidance

    NASA Astrophysics Data System (ADS)

    Uneri, A.; Wang, A. S.; Otake, Y.; Kleinszig, G.; Vogt, S.; Khanna, A. J.; Gallia, G. L.; Gokaslan, Z. L.; Siewerdsen, J. H.

    2014-09-01

    An algorithm for intensity-based 3D-2D registration of CT and C-arm fluoroscopy is evaluated for use in surgical guidance, specifically considering the low-dose limits of the fluoroscopic x-ray projections. The registration method is based on a framework using the covariance matrix adaptation evolution strategy (CMA-ES) to identify the 3D patient pose that maximizes the gradient information similarity metric. Registration performance was evaluated in an anthropomorphic head phantom emulating intracranial neurosurgery, using target registration error (TRE) to characterize accuracy and robustness in terms of 95% confidence upper bound in comparison to that of an infrared surgical tracking system. Three clinical scenarios were considered: (1) single-view image + guidance, wherein a single x-ray projection is used for visualization and 3D-2D guidance; (2) dual-view image + guidance, wherein one projection is acquired for visualization, combined with a second (lower-dose) projection acquired at a different C-arm angle for 3D-2D guidance; and (3) dual-view guidance, wherein both projections are acquired at low dose for the purpose of 3D-2D guidance alone (not visualization). In each case, registration accuracy was evaluated as a function of the entrance surface dose associated with the projection view(s). Results indicate that images acquired at a dose as low as 4 μGy (approximately one-tenth the dose of a typical fluoroscopic frame) were sufficient to provide TRE comparable or superior to that of conventional surgical tracking, allowing 3D-2D guidance at a level of dose that is at most 10% greater than conventional fluoroscopy (scenario #2) and potentially reducing the dose to approximately 20% of the level in a conventional fluoroscopically guided procedure (scenario #3).

  2. Unexpected behaviour of polystyrene-based scintillating fibers during irradiation at low doses and low dose rates

    NASA Astrophysics Data System (ADS)

    Wick, K.; Zoufal, T.

    2001-12-01

    The time dependence of the optical radiation damage process was studied for different fibers with polystyrene (PS) core. The fibers were irradiated with X-rays. In the present experiment the light guide BCF-98 (Bicron, clear polystyrene) was compared with the two scintillating fibers SCSF-38 and SCSF-81 (Kuraray). The light transmission through the fiber was investigated before, during and after irradiation. All investigated fibers showed unexpected effects depending on the fiber type: (1) at low doses the scintillating fibers are more sensitive to radiation than at high doses, i.e. the optical absorption rises nonlinearly with dose; (2) shortlived optical absorption centers decaying within several hours were detected in all fibers with PS core investigated up to now. Especially for SCSF-81, the annealing part is large and it totally overlaps the emission spectrum of the fiber.

  3. softMip: a novel projection algorithm for ultra-low-dose computed tomography.

    PubMed

    Meyer, Henning; Juran, Ralf; Rogalla, Patrik

    2008-01-01

    Two projection algorithms are currently available for viewing computed tomography (CT) data sets: average projection (AVG) and maximum intensity projection (MIP). Although AVG images feature good suppression of image noise but reduced edge sharpness, MIP images are characterized by good edge sharpness but also amplify image noise. Ultra-low-dose (ULD) CT has very low radiation exposure but has high image noise. Maximum intensity projection images of ULDCT data sets amplify image noise and are therefore unsuitable for image interpretation in the routine clinical setting. We developed a synthesis of both algorithms that tries to unite the respective advantages. The resulting softMip algorithm was implemented in C++ and installed on a workstation. Depending on the settings used, softMip images can represent any graduation between MIP and AVG. The new softMip algorithm was evaluated and compared with MIP and AVG in terms of image noise and edge sharpness in a series of phantom experiments performed on 7 different CT scanners. Furthermore, image quality of the transition from AVG to MIP by means of softMip was compared with the image quality of simply blending AVG and MIP. Images generated with softMip showed less image noise than MIP images (P < 0.0005) and higher edge sharpness than AVG images (P< 0.0005). The softMip transition from AVG to MIP had a better ratio of edge sharpness and image noise than blending (P < 0.0005). Our results suggest that softMip is a very promising projection procedure for postprocessing cross-sectional image data, especially ULDCT data sets. PMID:18520560

  4. Functional modulation on macrophage by low dose naltrexone (LDN).

    PubMed

    Yi, Zhe; Guo, Shengnan; Hu, Xu; Wang, Xiaonan; Zhang, Xiaoqing; Griffin, Noreen; Shan, Fengping

    2016-10-01

    Previously it was confirmed that naltrexone, a non-peptide δ-opioid receptor selective antagonist is mainly used for alcoholic dependence and opioid addiction treatment. However, there is increasing data on immune regulation of low dose naltrexone (LDN). The aim of this work was to explore the effect of LDN on the phenotype and function of macrophage. The changes of macrophage after treatment with LDN were examined using flow cytometry (FCM); FITC-dextran phagocytosis and enzyme-linked immunosorbent assay (ELISA). We have found that LDN enhances function of macrophage as confirmed by up-regulating MHC II molecule and CD64 on macrophage while down-regulating CD206 expression. Furthermore the productions of TNF-α, IL-6, IL-1β, increased significantly. Macrophages in LDN treated group performed the enhanced phagocytosis. Therefore it is concluded that LDN could promote function of macrophage and this work has provided concrete data of impact on immune system by LDN. Especially the data would support interaction between CD4+T cell and macrophage in AIDS treatment with LDN in Africa (LDN has already been approved in Nigeria for the use in AIDS treatment). PMID:27561742

  5. Role of heme Oxygenase-1 in low dose Radioadaptive response

    PubMed Central

    Bao, Lingzhi; Ma, Jie; Chen, Guodong; Hou, Jue; Hei, Tom K.; Yu, K.N.; Han, Wei

    2016-01-01

    Radioadaptive response (RAR) is an important phenomenon induced by low dose radiation. However, the molecular mechanism of RAR is obscure. In this study, we focused on the possible role of heme oxygenase 1 (HO-1) in RAR. Consistent with previous studies, priming dose of X-ray radiation (1–10 cGy) induced significant RAR in normal human skin fibroblasts (AG 1522 cells). Transcription and translation of HO-1 was up-regulated more than two fold by a priming dose of radiation (5 cGy). Zinc protoporphyrin Ⅸ, a specific competitive inhibitor of HO-1, efficiently inhibited RAR whereas hemin, an inducer of HO-1, could mimic priming dose of X-rays to induce RAR. Knocking down of HO-1 by transfection of HO-1 siRNA significantly attenuated RAR. Furthermore, the expression of HO-1 gene was modulated by the nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which translocated from cytoplasm to nucleus after priming dose radiation and enhance the antioxidant level of cells. PMID:26966892

  6. Fibrinolytic response in women on low-dose oral contraceptive.

    PubMed

    Ishak, R; Ahmad, R; Gudum, H R; Hassan, K; Ang, E S

    1992-06-01

    Long term use of low doses of combination oral contraceptives appears to increase plasminogen level, thereby increasing fibrinolytic activity and reducing the risk of thromboembolism. Blood levels of plasminogen, tissue plasminogen activator (tPA), and plasminogen activator inhibitor (PAI), were measured before and after stress (5 minutes of stair climbing) in a group of 30 women, 23-40 years old, who had taken 30 mcg of ethinyl estradiol with 150 mcg of desogestrel or levonorgestrel for at least 1 year. Similar measurements were taken from a control group of 30 women matched for age, height, and weight. Plasminogen and tPA levels in both groups increased significantly after exercise. The level of PAI did not change significantly with stress in either group. The level of plasminogen was significantly higher in the group taking contraceptives, whether before or after exercise, when compared to the control group. Levels of tPA and PAI, although slightly increased in the oral contraceptive group, were not significantly different between the two groups. The increase in plasminogen may be due to the estrogen component of the contraceptives. Stress seems to increase fibrinolytic response. PMID:12345026

  7. Low-dose caffeine physical dependence in humans.

    PubMed

    Griffiths, R R; Evans, S M; Heishman, S J; Preston, K L; Sannerud, C A; Wolf, B; Woodson, P P

    1990-12-01

    This study investigated the effects of terminating low dose levels of caffeine (100 mg/day) in 7 normal humans. Substitution of placebo capsules for caffeine capsules occurred under double-blind conditions while subjects rated various dimensions of their mood and behavior. In the first phase of the study, substitution of placebo for 12 consecutive days resulted in an orderly withdrawal syndrome in 4 subjects which peaked on days 1 or 2 and progressively decreased toward prewithdrawal levels over about 1 week. Data from the remaining three subjects provided no evidence of withdrawal. In the second phase of the study, the generality of the withdrawal effect was examined by repeatedly substituting placebo for 100 mg/day of caffeine for 1-day periods separated by an average of 9 days. Despite differences within and across subjects with respect to the presence, nature and magnitude of symptoms, each of the seven subjects demonstrated a statistically significant withdrawal effect. Although the phenomenon of caffeine withdrawal has been described previously, the present report documents that the incidence of caffeine withdrawal is higher (100% of subjects), the daily dose level at which withdrawal occurs is lower (roughly equivalent to the amount of caffeine in a single cup of strong brewed coffee or 3 cans of caffeinated soft drink) and the range of symptoms experienced is broader (including headache, fatigue and other dysphoric mood changes, muscle pain/stiffness, flu-like feelings, nausea/vomiting and craving for caffeine) than heretofore recognized. PMID:2262896

  8. Risk of cancer subsequent to low-dose radiation.

    PubMed

    Warren, S

    1980-10-01

    Prominent among media items related to the Three Mile Island episode were prophecies of future cancers. The credibility of some of these estimates are discussed. The average person has been exposed by the age of 50 to 2.5 rad (0.025 Gy) from natural background. We define low doses as under 25 rad (0.25 Gy). The most heavily exposed members of the general population during the Three Mile Island event received 83 mrad (0.83 mGy). Those exposed to 2500 mrad (25 mGy) would show no pathologically recognizable effects of radiation though there is evidence that chromosomal damage may occur with doses about 1 rad (0.01 Gy). An official stated among the consequences of the Three Mile Island accident that two additional cancer deaths would result. No epidemiologist could detect such an increase in the population at risk. It has been generally agreed that the linear hypothesis is useful for determining protection standards, not prognosis. Objective criteria for pathologic diagnosis of cause-effect relations are presented. PMID:7430985

  9. Comparison of Image Filters for Low Dose Neutron Imaging

    NASA Astrophysics Data System (ADS)

    Hungler, P. C.; Bennett, L. G. I.; Lewis, W. J.; Bevan, G.; Metzler, J.

    Neutron imaging using low flux sources, such as accelerators or low flux nuclear reactors, produces images which contain significant amounts of noise. The noise indications are a result of high energy gamma radiation and some neutron scattering which hit the CCD detector despite heavy shielding. The amount of noise in an image is a factor of the exposure time required to produce images with adequate dynamic ranges. Minimization of noise and maximization of the dynamic range are inversely proportional and the exposure time is often extended to increase incident neutrons at the expense of noise. The resultant noise can be reduced using image filters; however, these filters usually increase the signal to noise ratio (SNR) at the expense of spatial resolution. Three filters were applied to low dose neutron images acquired at RMC; a median filter, a Z-projection filter and a hybrid PDE filter. The median filter and the hybrid PDE filter showed similar performance in 3D with regards to SNR and spatial resolution, however, the median filter created numerous artefacts in the resultant tomogram. The Z-projection filter using 5 projections had the best performance in 2D improving the SNR of the raw image from 10.2 ± 0.767 to 22.5 ± 1.52 and the spatial resolution from 331 ± 2.89 to 309 ± 0.846, respectively. The Z-projection filter was not evaluated in 3D due to facility induced constraints.

  10. Low-dose radiation suppresses Pokemon expression under hypoxic conditions.

    PubMed

    Kim, Seung-Whan; Yu, Kweon; Shin, Kee-Sun; Kwon, Kisang; Hwang, Tae-Sik; Kwon, O-Yu

    2014-01-01

    Our previous data demonstrated that CoCl2-induced hypoxia controls endoplasmic reticulum (ER) stress-associated and other intracellular factors. One of them, the transcription factor Pokemon, was differentially regulated by low-dose radiation (LDR). There are limited data regarding how this transcription factor is involved in expression of the unfolded protein response (UPR) under hypoxic conditions. The purpose of this study was to obtain clues on how Pokemon is involved in the UPR. Pokemon was selected as a differentially expressed gene under hypoxic conditions; however, its regulation was clearly repressed by LDR. It was also demonstrated that both expression of ER chaperones and ER stress sensors were affected by hypoxic conditions, and the same results were obtained when cells in which Pokemon was up- or down-regulated were used. The current state of UPR and LDR research associated with the Pokemon pathway offers an important opportunity to understand the oncogenesis, senescence, and differentiation of cells, as well as to facilitate introduction of new therapeutic radiopharmaceuticals. PMID:24772825

  11. Analysis of repeated low-dose challenge studies.

    PubMed

    Nolen, Tracy L; Hudgens, Michael G; Senb, Pranab K; Koch, Gary G

    2015-05-30

    Preclinical evaluation of candidate human immunodeficiency virus (HIV) vaccines entails challenge studies whereby non-human primates such as macaques are vaccinated with either an active or control vaccine and then challenged (exposed) with a simian-version of HIV. Repeated low-dose challenge (RLC) studies in which each macaque is challenged multiple times (either until infection or some maximum number of challenges is reached) are becoming more common in an effort to mimic natural exposure to HIV in humans. Statistical methods typically employed for the testing for a vaccine effect in RLC studies include a modified version of Fisher's exact test as well as large sample approaches such as the usual log-rank test. Unfortunately, these methods are not guaranteed to provide a valid test for the effect of vaccination. On the other hand, valid tests for vaccine effect such as the exact log-rank test may not be easy to implement using software available to many researchers. This paper details which statistical approaches are appropriate for the analysis of RLC studies, and how to implement these methods easily in SAS or R. PMID:25752266

  12. Dosimetric Study of a Low-Dose-Rate Brachytherapy Source

    NASA Astrophysics Data System (ADS)

    Rodríguez-Villafuerte, M.; Arzamendi, S.; Díaz-Perches, R.

    Carcinoma of the cervix is the most common malignancy - in terms of both incidence and mortality - in Mexican women. Low dose rate (LDR) intracavitary brachytherapy is normally prescribed for the treatment of this disease to the vast majority of patients attending public hospitals in our country. However, most treatment planning systems being used in these hospitals still rely on Sievert integral dose calculations. Moreover, experimental verification of dose distributions are hardly ever done. In this work we present a dosimetric characterisation of the Amersham CDCS-J 137Cs source, an LDR brachytherapy source commonly used in Mexican hospitals. To this end a Monte Carlo simulation was developed, that includes a realistic description of the internal structure of the source embedded in a scattering medium. The Monte Carlo results were compared to experimental measurements of dose distributions. A lucite phantom with the same geometric characteristics as the one used in the simulation was built. Dose measurements were performed using thermoluminescent dosimeters together with commercial RadioChromic dye film. A comparison between our Monte Carlo simulation, the experimental data, and results reported in the literature is presented.

  13. Differentially Expressed Genes Associated with Low-Dose Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Hegyesi, Hargita; Sándor, Nikolett; Schilling, Boglárka; Kis, Enikő; Lumniczky, Katalin; Sáfrány, Géza

    We have studied low dose radiation induced gene expression alterations in a primary human fibroblast cell line using Agilent's whole human genome microarray. Cells were irradiated with 60Co γ-rays (0; 0.1; 0.5 Gy) and 2 hours later total cellular RNA was isolated. We observed differential regulation of approximately 300-500 genes represented on the microarray. Of these, 126 were differentially expressed at both doses, among them significant elevation of GDF-15 and KITLG was confirmed by qRT-PCR. Based on the transcriptional studies we selected GDF-15 to assess its role in radiation response, since GDF-15 is one of the p53 gene targets and is believed to participate in mediating p53 activities. First we confirmed gamma-radiation induced dose-dependent changes in GDF-15 expression by qRT-PCR. Next we determined the effect of GDF-15 silencing on radiosensitivity. Four GDF-15 targeting shRNA expressing lentiviral vectors were transfected into immortalized human fibroblast cells. We obtained efficient GDF-15 silencing in one of the four constructs. RNA interference inhibited GDF-15 gene expression and enhanced the radiosensitivity of the cells. Our studies proved that GDF-15 plays an essential role in radiation response and may serve as a promising target in radiation therapy.

  14. Information content of low-dose radiographs: Part 2

    SciTech Connect

    Morris, R.A.

    1997-10-01

    The previous paper described the concept of using the net number of information bits transmitted in a radiographic image as a measure of the contrast parameter of image quality. The concept is particularly useful when the image contrast is limited by the statistics of the photon fluence incident on the detector (low doses). The Wolfram Research Mathematica program (described in Ref. 1) that was used to simulate a noisy image of an object with two thicknesses and to calculate the resulting IC (information content). The only noise source in the simulation was fluctuations in the photon fluence incident on the detector. The results from the simulation were compared to data obtained from actual radiographs of a copper step wedge radiographed with 10 and 50 pulses from a 150-p, V x-ray machine. Good agreement between the simulation and experiment was obtained when the photon fluence was considered a free, adjustable parameter. This report extends the simulation described in Ref. 1 and shows how IC varies as the following radiographic parameters change: object thickness; object Z number; x-ray energy; and incident x-ray fluence.

  15. Role of heme Oxygenase-1 in low dose Radioadaptive response.

    PubMed

    Bao, Lingzhi; Ma, Jie; Chen, Guodong; Hou, Jue; Hei, Tom K; Yu, K N; Han, Wei

    2016-08-01

    Radioadaptive response (RAR) is an important phenomenon induced by low dose radiation. However, the molecular mechanism of RAR is obscure. In this study, we focused on the possible role of heme oxygenase 1 (HO-1) in RAR. Consistent with previous studies, priming dose of X-ray radiation (1-10cGy) induced significant RAR in normal human skin fibroblasts (AG 1522 cells). Transcription and translation of HO-1 was up-regulated more than two fold by a priming dose of radiation (5cGy). Zinc protoporphyrin Ⅸ, a specific competitive inhibitor of HO-1, efficiently inhibited RAR whereas hemin, an inducer of HO-1, could mimic priming dose of X-rays to induce RAR. Knocking down of HO-1 by transfection of HO-1 siRNA significantly attenuated RAR. Furthermore, the expression of HO-1 gene was modulated by the nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which translocated from cytoplasm to nucleus after priming dose radiation and enhance the antioxidant level of cells. PMID:26966892

  16. Sensitivity to low-dose radiation in radiosensitive wasted mice

    SciTech Connect

    Paunesku, T.; Protic, M.; Woloschak, G. E.

    1999-11-12

    Mice homozygous for the autosomal recessive wasted mutation (wst/wst) have abnormalities in T-lymphocytes and in the anterior motor neuron cells of the spinal cord, leading to sensitivity to low doses of ionizing radiation, hind limb paralysis, and immunodeficiency. This defect results in a failure to gain weight by 20 days and death at 28 days of age. The wasted mutation (previously mapped to mouse chromosome 2) is shown to be a 3-bp deletion in a T-cell-specific (and perhaps motor-neuron-specific) regulatory region (promoter) of the proliferating cell nuclear antigen (PCNA) gene on mouse chromosome 2. A regulatory element is also shown to be important in PCNA expression in T-lymphocytes and motor neuron cells afflicted by the 3-bp deletion in the PCNA promoter. The model is as follows: Absence of PCNA expression in the thymuses (and motor neurons) of wasted mice causes cellular apoptosis; this absence of expression is mediated by a positive transactor that can bind to the wild-type but not the wasted mutant PCNA promoter; the bound protein induces late expression of PCNA in T-lymphocytes and prevents onset of radiation sensitivity in the cells.

  17. Automated aortic calcium scoring on low-dose chest computed tomography

    SciTech Connect

    Isgum, Ivana; Rutten, Annemarieke; Prokop, Mathias; Staring, Marius; Klein, Stefan; Pluim, Josien P. W.; Viergever, Max A.; Ginneken, Bram van

    2010-02-15

    Purpose: Thoracic computed tomography (CT) scans provide information about cardiovascular risk status. These scans are non-ECG synchronized, thus precise quantification of coronary calcifications is difficult. Aortic calcium scoring is less sensitive to cardiac motion, so it is an alternative to coronary calcium scoring as an indicator of cardiovascular risk. The authors developed and evaluated a computer-aided system for automatic detection and quantification of aortic calcifications in low-dose noncontrast-enhanced chest CT. Methods: The system was trained and tested on scans from participants of a lung cancer screening trial. A total of 433 low-dose, non-ECG-synchronized, noncontrast-enhanced 16 detector row examinations of the chest was randomly divided into 340 training and 93 test data sets. A first observer manually identified aortic calcifications on training and test scans. A second observer did the same on the test scans only. First, a multiatlas-based segmentation method was developed to delineate the aorta. Segmented volume was thresholded and potential calcifications (candidate objects) were extracted by three-dimensional connected component labeling. Due to image resolution and noise, in rare cases extracted candidate objects were connected to the spine. They were separated into a part outside and parts inside the aorta, and only the latter was further analyzed. All candidate objects were represented by 63 features describing their size, position, and texture. Subsequently, a two-stage classification with a selection of features and k-nearest neighbor classifiers was performed. Based on the detected aortic calcifications, total calcium volume score was determined for each subject. Results: The computer system correctly detected, on the average, 945 mm{sup 3} out of 965 mm{sup 3} (97.9%) calcified plaque volume in the aorta with an average of 64 mm{sup 3} of false positive volume per scan. Spearman rank correlation coefficient was {rho}=0.960 between

  18. Health Risks From Low Doses and Low Dose-Rates of Ionizing Radiation. Session 5: Future of Radiation Protection Regulations.

    PubMed

    Cool, Donald A

    2016-03-01

    The system of radiological protection is a prospective approach to protection of individuals in all exposure situations. It must be applied equitably across all age groups and all populations. This is a very different circumstance from dose assessment for a particular individual where the unique characteristics of the individual and the exposure can be taken into account. Notwithstanding the ongoing discussions on the possible shape of the dose response at low doses and dose rates, the prospective system of protection has therefore historically used a linear assumption as a pragmatic, prudent and protective approach. These radiation protection criteria are not intended to be a demarcation between "safe" and "unsafe" and are the product of a risk-informed judgement that includes inputs from science, ethics, and experience. There are significant implications for different dose response relationships. A linear model allows for equal treatment of an exposure, irrespective of the previously accumulated exposure. In contrast, other models would predict different implications. Great care is therefore needed in separating the thinking around risk assessment from risk management, and prospective protection for all age groups and genders from retrospective assessment for a particular individual. In the United States, the prospective regulatory structure functions effectively because of assumptions that facilitate independent treatment of different types of exposures, and which provide pragmatic and prudent protection. While the a linear assumption may, in fact, not be consistent with the biological reality, the implications of a different regulatory model must be considered carefully. PMID:26808877

  19. Clinical low dose CT image reconstruction using high-order total variation techniques

    NASA Astrophysics Data System (ADS)

    Do, Synho; Karl, W. Clem; Kalra, Mannudeep K.; Brady, Thomas J.; Pien, Homer

    2010-04-01

    Total variation (TV) based iterative image reconstruction has been shown to possess desirable noise suppression and edge preservation characteristics. However, such approaches also produce "staircase effects" where intensity ramps are discretized into steps, resulting in images which appear blocky or patchy. In this paper, we present an improved regularization technique by incorporating higher-order derivatives to reduce staircase artifacts without sacrificing edge sharpness. In this preliminary investigation we demonstrate our approach using both phantom and clinical images acquired at 25% of conventional radiation dosage (i.e., 75% dose reduction).

  20. [Relationship to Carcinogenesis of Repetitive Low-Dose Radiation Exposure].

    PubMed

    Ootsuyama, Akira

    2016-06-01

    We studied the carcinogenic effects caused by repetitive irradiation at a low dose, which has received attention in recent years, and examined the experimental methods used to evaluate radiation-induced carcinogenesis. For this experiment, we selected a mouse with as few autochthonous cancers as possible. Skin cancer was selected as the target for analysis, because it is a rare cancer in mice. Beta-rays were selected as the radiation source. The advantage of using beta-rays is weaker penetration power into tissues, thus protecting organs, such as the digestive and hematogenous organs. The benefit of our experimental method is that only skin cancer requires monitoring, and it is possible to perform long-term experiments. The back skin of mice was exposed repetitively to beta-rays three times a week until the occurrence of cancer or death, and the dose per exposure ranged from 0.5 to 11.8 Gy. With the high-dose range (2.5-11.8 Gy), the latency period and carcinogenic rate were almost the same in each experimental group. When the dose was reduced to 1-1.5 Gy, the latency period increased, but the carcinogenic rate remained. When the dose was further reduced to 0.5 Gy, skin cancer never happened, even though we continued irradiation until death of the last mouse in this group. The lifespan of 0.5 Gy group mice was the same as that of the controls. We showed that the 0.5 Gy dose did not cause cancer, even in mice exposed repetitively throughout their life span, and thus refer to 0.5 Gy as the threshold-like dose. PMID:27302731

  1. High versus Low-Dose Rate Brachytherapy for Cervical Cancer

    PubMed Central

    Patankar, Sonali S.; Tergas, Ana I.; Deutsch, Israel; Burke, William M.; Hou, June Y.; Ananth, Cande V.; Huang, Yongmei; Neugut, Alfred I.; Hershman, Dawn L.; Wright, Jason D.

    2015-01-01

    Objectives Brachytherapy plays an important role in the treatment of cervical cancer. While small trials have shown comparable survival outcomes between high (HDR) and low-dose rate (LDR) brachytherapy, little data is available in the US. We examined the utilization of HDR brachytherapy and analyzed the impact of type of brachytherapy on survival for cervical cancer. Methods Women with stage IB2–IVA cervical cancer treated with primary (external beam and brachytherapy) radiotherapy between 2003–2011 and recorded in the National Cancer Database (NCDB) were analyzed. Generalized linear mixed models and Cox proportional hazards regression were used to examine predictors of HDR brachytherapy use and the association between HDR use and survival. Results A total of 10,564 women including 2681 (25.4%) who received LDR and 7883 (74.6%) that received HDR were identified. Use of HDR increased from 50.2% in 2003 to 83.9% in 2011 (P<0.0001). In a multivariable model, year of diagnosis was the strongest predictor of use of HDR. While patients in the Northeast were more likely to receive HDR therapy, there were no other clinical or socioeconomic characteristics associated with receipt of HDR. In a multivariable Cox model, survival was similar between the HDR and LDR groups (HR=0.93; 95% 0.83–1.03). Similar findings were noted in analyses stratified by stage and histology. Kaplan-Meier analyses demonstrated no difference in survival based on type of brachytherapy for stage IIB (P=0.68), IIIB (P=0.17), or IVA (P=0.16) tumors. Conclusions The use of HDR therapy has increased rapidly. Overall survival is similar for LDR and HDR brachytherapy. PMID:25575481

  2. Small bowel injury in low-dose aspirin users.

    PubMed

    Endo, Hiroki; Sakai, Eiji; Kato, Takayuki; Umezawa, Shotaro; Higurashi, Takuma; Ohkubo, Hidenori; Nakajima, Atsushi

    2015-04-01

    The use of low-dose aspirin (LDA) is well known to be associated with an increased risk of serious upper gastrointestinal complications, such as peptic ulceration and bleeding. Until recently, attention was mainly focused on aspirin-induced damage of the stomach and duodenum. However, recently, there has been growing interest among gastroenterologists on the adverse effects of aspirin on the small bowel, especially as new endoscopic techniques, such as capsule endoscopy (CE) and balloon-assisted endoscopy, have become available for the evaluation of small bowel lesions. Preliminary CE studies conducted in healthy subjects have shown that short-term administration of LDA can induce mild mucosal inflammation of the small bowel. Furthermore, chronic use of LDA results in a variety of lesions in the small bowel, including multiple petechiae, loss of villi, erosions, and round, irregular, or punched-out ulcers. Some patients develop circumferential ulcers with stricture. In addition, to reduce the incidence of gastrointestinal lesions in LDA users, it is important for clinicians to confirm the differences in the gastrointestinal toxicity between different types of aspirin formulations in clinical use. Some studies suggest that enteric-coated aspirin may be more injurious to the small bowel mucosa than buffered aspirin. The ideal treatment for small bowel injury in patients taking LDA would be withdrawal of aspirin, however, LDA is used as an antiplatelet agent in the majority of patients, and its withdrawal could increase the risk of cardiovascular/cerebrovascular morbidity and mortality. Thus, novel means for the treatment of aspirin-induced enteropathy are urgently needed. PMID:25501289

  3. CT of nontraumatic thoracic aortic emergencies.

    PubMed

    Bhalla, Sanjeev; West, O Clark

    2005-10-01

    Computed tomography (CT), especially multidetector row CT (MDCT), is often the preferred imaging test used for evaluation of nontraumatic thoracic aortic abnormalities. Unenhanced images, usually followed by contrast-enhanced arterial imaging, allow for rapid detailed aortic assessment. Understanding the spectrum of acute thoracic aortic conditions which may present similarly (aortic dissection, aneurysm rupture, penetrating atherosclerotic ulcer, intramural hematoma) will ensure that patients are diagnosed and treated appropriately. Familiarity with imaging protocols and potential mimics will prevent confusion of normal anatomy and variants with aortic disease. PMID:16274000

  4. The MAGIC-5 CAD for nodule detection in low dose and thin slice lung CTs

    NASA Astrophysics Data System (ADS)

    Cerello, Piergiorgio; MAGIC-5 Collaboration

    2010-11-01

    Lung cancer is the leading cause of cancer-related mortality in developed countries. Only 10-15% of all men and women diagnosed with lung cancer live 5 years after the diagnosis. However, the 5-year survival rate for patients diagnosed in the early asymptomatic stage of the disease can reach 70%. Early-stage lung cancers can be diagnosed by detecting non-calcified small pulmonary nodules with computed tomography (CT). Computer-aided detection (CAD) could support radiologists in the analysis of the large amount of noisy images generated in screening programs, where low-dose and thin-slice settings are used. The MAGIC-5 project, funded by the Istituto Nazionale di Fisica Nucleare (INFN, Italy) and Ministero dell'Università e della Ricerca (MUR, Italy), developed a multi-method approach based on three CAD algorithms to be used in parallel with a merging of their results: the Channeler Ant Model (CAM), based on Virtual Ant Colonies, the Dot-Enhancement/Pleura Surface Normals/VBNA (DE-PSN-VBNA), and the Region Growing Volume Plateau (RGVP). Preliminary results show quite good performances, to be improved with the refining of the single algorithm and the added value of the results merging.

  5. Radiobiological Response of Cervical Cancer Cell Line in Low Dose Region: Evidence of Low Dose Hypersensitivity (HRS) and Induced Radioresistance (IRR)

    PubMed Central

    Singh, Rabiraja; George, Daicy; Vijaykumar, T.S.; John, Subhashini

    2015-01-01

    Background Purpose of the present study was to examine the response of cervical cancer cell line (HeLa cell line) to low dose radiation using clonogenic assay and mathematical modeling of the low dose response by Joiner’s induced repair model. Materials and Methods Survival of HeLa cells following exposure to single and fractionated low doses of γ (gamma)-ray, 6 MV, and 15 MV photon was measured by clonogenic assay. Results HeLa cell line demonstrated marked low dose response consisting of an area of HRS and IRR in the dose region of <1 Gy. The two gradients of the low dose region (αs and αr) were distinctly different with a transition dose (Dc) of 0.28-0.40 cGy. Conclusion HeLa cell line demonstrates marked HRS and IRR with distinct transition dose. This may form the biological basis of the clinical study to investigate the chemo potentiating effect of low dose radiation in cervical cancer. PMID:26266200

  6. Dosimetry Modeling for Focal Low-Dose-Rate Prostate Brachytherapy

    SciTech Connect

    Al-Qaisieh, Bashar; Mason, Josh; Bownes, Peter; Henry, Ann; Dickinson, Louise; Ahmed, Hashim U.; Emberton, Mark; Langley, Stephen

    2015-07-15

    Purpose: Focal brachytherapy targeted to an individual lesion(s) within the prostate may reduce side effects experienced with whole-gland brachytherapy. The outcomes of a consensus meeting on focal prostate brachytherapy were used to investigate optimal dosimetry of focal low-dose-rate (LDR) prostate brachytherapy targeted using multiparametric magnetic resonance imaging (mp-MRI) and transperineal template prostate mapping (TPM) biopsy, including the effects of random and systematic seed displacements and interseed attenuation (ISA). Methods and Materials: Nine patients were selected according to clinical characteristics and concordance of TPM and mp-MRI. Retrospectively, 3 treatment plans were analyzed for each case: whole-gland (WG), hemi-gland (hemi), and ultra-focal (UF) plans, with 145-Gy prescription dose and identical dose constraints for each plan. Plan robustness to seed displacement and ISA were assessed using Monte Carlo simulations. Results: WG plans used a mean 28 needles and 81 seeds, hemi plans used 17 needles and 56 seeds, and UF plans used 12 needles and 25 seeds. Mean D90 (minimum dose received by 90% of the target) and V100 (percentage of the target that receives 100% dose) values were 181.3 Gy and 99.8% for the prostate in WG plans, 195.7 Gy and 97.8% for the hemi-prostate in hemi plans, and 218.3 Gy and 99.8% for the focal target in UF plans. Mean urethra D10 was 205.9 Gy, 191.4 Gy, and 92.4 Gy in WG, hemi, and UF plans, respectively. Mean rectum D2 cm{sup 3} was 107.5 Gy, 77.0 Gy, and 42.7 Gy in WG, hemi, and UF plans, respectively. Focal plans were more sensitive to seed displacement errors: random shifts with a standard deviation of 4 mm reduced mean target D90 by 14.0%, 20.5%, and 32.0% for WG, hemi, and UF plans, respectively. ISA has a similar impact on dose-volume histogram parameters for all plan types. Conclusions: Treatment planning for focal LDR brachytherapy is feasible. Dose constraints are easily met with a notable

  7. Lyssavirus infection: 'low dose, multiple exposure' in the mouse model.

    PubMed

    Banyard, Ashley C; Healy, Derek M; Brookes, Sharon M; Voller, Katja; Hicks, Daniel J; Núñez, Alejandro; Fooks, Anthony R

    2014-03-01

    The European bat lyssaviruses (EBLV-1 and EBLV-2) are zoonotic pathogens present within bat populations across Europe. The maintenance and transmission of lyssaviruses within bat colonies is poorly understood. Cases of repeated isolation of lyssaviruses from bat roosts have raised questions regarding the maintenance and intraspecies transmissibility of these viruses within colonies. Furthermore, the significance of seropositive bats in colonies remains unclear. Due to the protected nature of European bat species, and hence restrictions to working with the natural host for lyssaviruses, this study analysed the outcome following repeat inoculation of low doses of lyssaviruses in a murine model. A standardized dose of virus, EBLV-1, EBLV-2 or a 'street strain' of rabies (RABV), was administered via a peripheral route to attempt to mimic what is hypothesized as natural infection. Each mouse (n=10/virus/group/dilution) received four inoculations, two doses in each footpad over a period of four months, alternating footpad with each inoculation. Mice were tail bled between inoculations to evaluate antibody responses to infection. Mice succumbed to infection after each inoculation with 26.6% of mice developing clinical disease following the initial exposure across all dilutions (RABV, 32.5% (n=13/40); EBLV-1, 35% (n=13/40); EBLV-2, 12.5% (n=5/40)). Interestingly, the lowest dose caused clinical disease in some mice upon first exposure ((RABV, 20% (n=2/10) after first inoculation; RABV, 12.5% (n=1/8) after second inoculation; EBLV-2, 10% (n=1/10) after primary inoculation). Furthermore, five mice developed clinical disease following the second exposure to live virus (RABV, n=1; EBLV-1, n=1; EBLV-2, n=3) although histopathological examination indicated that the primary inoculation was the most probably cause of death due to levels of inflammation and virus antigen distribution observed. All the remaining mice (RABV, n=26; EBLV-1, n=26; EBLV-2, n=29) survived the tertiary and

  8. Radiological and clinical outcome of screw placement in adolescent idiopathic scoliosis: evaluation with low-dose computed tomography

    PubMed Central

    Ohlin, Acke; Strömbeck, Anita; Maly, Pavel; Sundgren, Pia C.

    2009-01-01

    Posterior corrective surgery using “all pedicle screw construct” carries risk of neurovascular complications. The study aims were to assess the screw placement in patients with adolescent idiopathic scoliosis using CT with low-radiation dose, and to evaluate the clinical outcome in patients with misplaced pedicle screws. CTs of 49 consecutive patients (873 screws, 79% thoracic) were retrospectively evaluated by two independent radiologists. A new grading system was developed to distinguish between lateral, medial and anterior cortical perforations, endplate perforation and foraminal perforation. The grading system is based on whether the cortical violation is partial or total rather than on mm-basis. The overall rate of screw misplacement was 17% (n = 149): 8% were laterally placed and 6.1% were medially placed. The rates of anterior cortical, endplate and foraminal perforation were 1.5, 0.9, and 0.5%, respectively. Lateral cortical perforation was more frequent in the thoracic spine (P = 0.005), whereas other types of misplacement including medial cortical perforation were more frequent on the left and the concave side of scoliotic curves (P = 0.002 and 0.003). No neurovascular complications were reported. The association between the occurrence of screw misplacement and the Cobb angle was statistically significant (P = 0.037). Misplacements exceeding half screw diameter should be classified as unacceptable. Low-dose CT implies exposing these young individuals to a significantly lower radiation dose than do other protocols used in daily clinical practice. We recommend using low-dose CT and the grading system proposed here in the postoperative assessment of screw placement. PMID:19888607

  9. Imprinted genes and transpositions: epigenomic targets for low dose radiation effects. Final report

    SciTech Connect

    Jirtle, Randy L.

    2012-10-11

    The overall hypothesis of this grant application is that low dose ionizing radiation (LDIR) elicits adaptive responses in part by causing heritable DNA methylation changes in the epigenome. This novel postulate was tested by determining if the level of DNA methylation at the Agouti viable yellow (A{sup vy}) metastable locus is altered, in a dose-dependent manner, by low dose radiation exposure (<10 cGy) during early gestation. This information is particularly important to ascertain given the increased use of CT scans in disease diagnosis, increased number of people predicted to live and work in space, and the present concern about radiological terrorism. We showed for the first time that LDIR significantly increased DNA methylation at the A{sup vy} locus in a sex-specific manner (p=0.004). Average DNA methylation was significantly increased in male offspring exposed to doses between 0.7 cGy and 7.6 cGy with maximum effects at 1.4 cGy and 3.0 cGy (p<0.01). Offspring coat color was concomitantly shifted towards pseudoagouti (p<0.01). Maternal dietary antioxidant supplementation mitigated both the DNA methylation changes and coat color shift in the irradiated offspring (p<0.05). Thus, LDIR exposure during gestation elicits epigenetic alterations that lead to positive adaptive phenotypic changes that are negated with antioxidants, indicating they are mediated in part by oxidative stress. These findings provide evidence that in the isogenic Avy mouse model epigenetic alterations resulting from LDIR play a role in radiation hormesis, bringing into question the assumption that every dose of radiation is harmful. Our findings not only have significant implications concerning the mechanism of hormesis, but they also emphasize the potential importance of this phenomenon in determining human risk at low radiation doses. Since the epigenetic regulation of genes varies markedly between species, the effect of LDIR on other epigenetically labile genes (e.g. imprinted genes) in

  10. The effects of repeated low-dose sarin exposure

    SciTech Connect

    Shih, T.-M. . E-mail: tsungming.a.shih@us.army.mil; Hulet, S.W.; McDonough, J.H.

    2006-09-01

    This project assessed the effects of repeated low-dose exposure of guinea pigs to the organophosphorus nerve agent sarin. Animals were injected once a day, 5 days per week (Monday-Friday), for 2 weeks with fractions (0.3x, 0.4x, 0.5x, or 0.6x) of the established LD{sub 5} dose of sarin (42 {mu}g/kg, s.c.). The animals were assessed for changes in body weight, red blood cell (RBC) acetylcholinesterase (AChE) levels, neurobehavioral reactions to a functional observational battery (FOB), cortical electroencephalographic (EEG) power spectrum, and intrinsic acetylcholine (ACh) neurotransmitter (NT) regulation over the 2 weeks of sarin exposure and for up to 12 days postinjection. No guinea pig receiving 0.3, 0.4 or 0.5 x LD{sub 5} of sarin showed signs of cortical EEG seizures despite decreases in RBC AChE levels to as low as 10% of baseline, while seizures were evident in animals receiving 0.6 x LD{sub 5} of sarin as early as the second day; subsequent injections led to incapacitation and death. Animals receiving 0.5 x LD{sub 5} sarin showed obvious signs of cholinergic toxicity; overall, 2 of 13 animals receiving 0.5 x LD{sub 5} sarin died before all 10 injections were given, and there was a significant increase in the angle of gait in the animals that lived. By the 10th day of injection, the animals receiving saline were significantly easier to remove from their cages and handle and significantly less responsive to an approaching pencil and touch on the rump in comparison with the first day of testing. In contrast, the animals receiving 0.4 x LD{sub 5} sarin failed to show any significant reductions in their responses to an approaching pencil and a touch on the rump as compared with the first day. The 0.5 x LD{sub 5} sarin animals also failed to show any significant changes to the approach and touch responses and did not adjust to handling or removal from the cage from the first day of injections to the last day of handling. Thus, the guinea pigs receiving the 0

  11. Molecular dissection of the roles of the SOD genes in mammalian response to low dose irradiation

    SciTech Connect

    Li, Chuan-Yaun

    2009-01-27

    “Molecular dissection of the roles of the SOD genes in mammalian response to low dose irradiation " was started on 09/01/03 and ended on 08/31/07. The primary objective of the project was to carry out mechanistic studies of the roles of the anti-oxidant SOD genes in mammalian cellular response to low dose ionizing radiation.

  12. Low doses of glyphosate change the response of soybean to later glyphosate exposures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The stimulatory effect of low doses of toxic substances is known as hormesis. Many herbicides that cause severe injury to plants at recommended rates, promote growth or have other stimulatory effects at very low doses. The objective of this study was to evaluate glyphosate-induced hormesis in soyb...

  13. Effects of low dose FGF-2 and BMP-2 on healing of calvarial defects in old mice.

    PubMed

    Charles, Lyndon F; Woodman, Jessica L; Ueno, Daisuke; Gronowicz, Gloria; Hurley, Marja M; Kuhn, Liisa T

    2015-04-01

    There is an age-associated reduction in the bone healing activity of bone morphogenetic protein-2 (BMP-2) that is currently addressed by administering higher doses of BMP-2 in elderly patients. The unwanted medical complications from high dose BMP-2 motivated this investigation to determine whether the addition of a low dose of fibroblast growth factor 2 (FGF-2) could enhance the ability of a lower dose of BMP-2 to heal calvarial bone defects in old mice (18-20 months old). FGF-2 (5 ng) and BMP-2 (2 μg) were administered by a controlled release two-phase biomaterial scaffold placed into the bone defect. FGF-2 released more rapidly and completely in vitro than BMP-2 (40% vs 2%). In vivo, both BMP-2 and FGF-2+BMP-2 groups formed more new bone in calvarial defects than scaffold alone (p < 0.001) or FGF-2 only groups (p < 0.01). The overall total volume of new bone was not statistically increased by the addition of FGF-2 to BMP-2 as measured by microCT, but the pattern of bone deposition was different. In old mice, but not young, there was enhanced bony fill in the central bone defect area when the BMP-2 was supplemented with FGF-2. Histological analysis of the center of the defect revealed an increased bone volume (%BV/TV (p = 0.004)) from the addition of FGF-2. These studies suggest that combining a low dose of FGF-2 with a low dose of BMP-2 has the potential to increase bone healing in old mice relative to BMP-2 alone. PMID:25681640

  14. Effects of Low Dose FGF-2 and BMP-2 on Healing of Calvarial Defects in Old Mice

    PubMed Central

    Charles, Lyndon F.; Woodman, Jessica L.; Ueno, Daisuke; Gronowicz, Gloria; Hurley, Marja M.; Kuhn, Liisa T.

    2015-01-01

    There is an age-associated reduction in the bone healing activity of bone morphogenetic protein -2 (BMP-2) that is currently addressed by administering higher doses of BMP-2 in elderly patients. The unwanted medical complications from high dose BMP-2 motivated this investigation to determine whether the addition of a low dose of fibroblast growth factor 2 (FGF-2) could enhance the ability of a lower dose of BMP-2 to heal calvarial bone defects in old mice (18-20 months old). FGF-2 (5 ng) and BMP-2 (2 μg) were administered by a controlled release two-phase biomaterial scaffold placed into the bone defect. FGF-2 released more rapidly and completely in vitro than BMP-2 (40% vs 2%). In vivo, both BMP-2 and FGF-2+BMP-2 groups formed more new bone in calvarial defects than scaffold alone (p <0.001) or FGF-2 only groups (p < 0.01). The overall total volume of new bone was not statistically increased by the addition of FGF-2 to BMP-2 as measured by microCT, but the pattern of bone deposition was different. In old mice, but not young, there was enhanced bony fill in the central bone defect area when the BMP-2 was supplemented with FGF-2. Histological analysis of the center of the defect revealed an increased bone volume (%BV/TV (p = 0.004)) from the addition of FGF-2. These studies suggest that combining a low dose of FGF-2 with a low dose of BMP-2 has the potential to increase bone healing in old mice relative to BMP-2 alone. PMID:25681640

  15. Chemoprevention of DMBA-induced mammary carcinogenesis in rats by low-dose EPA and DHA.

    PubMed Central

    Noguchi, M.; Minami, M.; Yagasaki, R.; Kinoshita, K.; Earashi, M.; Kitagawa, H.; Taniya, T.; Miyazaki, I.

    1997-01-01

    We investigated the effects of low-dose eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the incidence and growth of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in rats fed a high-fat (HF) diet. We also examined the effects of these treatments on the fatty acid composition of tumour and serum. Tumour incidence was significantly decreased by the administration of low-dose EPA and DHA, whereas their inhibitory effects on tumour growth did not reach significance. Serum arachidonic acid (AA) level was decreased by the administration of low-dose EPA and tended to be decreased by the administration of low-dose DHA, whereas tumour AA levels were not changed. The administration of low-dose EPA and DHA may be useful for inhibiting the incidence of breast cancer. PMID:9020478

  16. Analysis of renal impairment in MM-003, a phase III study of pomalidomide + low - dose dexamethasone versus high - dose dexamethasone in refractory or relapsed and refractory multiple myeloma.

    PubMed

    Weisel, Katja C; Dimopoulos, Meletios A; Moreau, Philippe; Lacy, Martha Q; Song, Kevin W; Delforge, Michel; Karlin, Lionel; Goldschmidt, Hartmut; Banos, Anne; Oriol, Albert; Alegre, Adrian; Chen, Christine; Cavo, Michele; Garderet, Laurent; Ivanova, Valentina; Martinez-Lopez, Joaquin; Knop, Stefan; Yu, Xin; Hong, Kevin; Sternas, Lars; Jacques, Christian; Zaki, Mohamed H; San Miguel, Jesus

    2016-07-01

    Pomalidomide + low-dose dexamethasone is effective and well tolerated for refractory or relapsed and refractory multiple myeloma after bortezomib and lenalidomide failure. The phase III trial MM-003 compared pomalidomide + low-dose dexamethasone with high-dose dexamethasone. This subanalysis grouped patients by baseline creatinine clearance ≥ 30 - < 60 mL/min (n=93, pomalidomide + low-dose dexamethasone; n=56, high-dose dexamethasone) or ≥ 60 mL/min (n=205, pomalidomide + low-dose dexamethasone; n=93, high-dose dexamethasone). Median progression-free survival was similar for both subgroups and favored pomalidomide + low-dose dexamethasone versus high-dose dexamethasone: 4.0 versus 1.9 months in the group with baseline creatinine clearance ≥ 30 - < 60 mL/min (P<0.001) and 4.0 versus 2.0 months in the group with baseline creatinine clearance ≥ 60 mL/min (P<0.001). Median overall survival for pomalidomide + low-dose dexamethasone versus high-dose dexamethasone was 10.4 versus 4.9 months (P=0.030) and 15.5 versus 9.2 months (P=0.133), respectively. Improved renal function, defined as an increase in creatinine clearance from < 60 to ≥ 60 mL/min, was similar in pomalidomide + low-dose dexamethasone and high-dose dexamethasone patients (42% and 47%, respectively). Improvement in progression-free and overall survival in these patients was comparable with that in patients without renal impairment. There was no increase in discontinuations of therapy, dose modifications, and adverse events in patients with moderate renal impairment. Pomalidomide at a starting dose of 4 mg + low-dose dexamethasone is well tolerated in patients with refractory or relapsed and refractory multiple myeloma, and of comparable efficacy if moderate renal impairment is present. This trial was registered with clinicaltrials.gov identifier 01311687 and EudraCT identifier 2010-019820-30. PMID:27081177

  17. Analysis of renal impairment in MM-003, a phase III study of pomalidomide + low - dose dexamethasone versus high - dose dexamethasone in refractory or relapsed and refractory multiple myeloma

    PubMed Central

    Weisel, Katja C.; Dimopoulos, Meletios A.; Moreau, Philippe; Lacy, Martha Q.; Song, Kevin W.; Delforge, Michel; Karlin, Lionel; Goldschmidt, Hartmut; Banos, Anne; Oriol, Albert; Alegre, Adrian; Chen, Christine; Cavo, Michele; Garderet, Laurent; Ivanova, Valentina; Martinez-Lopez, Joaquin; Knop, Stefan; Yu, Xin; Hong, Kevin; Sternas, Lars; Jacques, Christian; Zaki, Mohamed H.; Miguel, Jesus San

    2016-01-01

    Pomalidomide + low-dose dexamethasone is effective and well tolerated for refractory or relapsed and refractory multiple myeloma after bortezomib and lenalidomide failure. The phase III trial MM-003 compared pomalidomide + low-dose dexamethasone with high-dose dexamethasone. This subanalysis grouped patients by baseline creatinine clearance ≥ 30 − < 60 mL/min (n=93, pomalidomide + low-dose dexamethasone; n=56, high-dose dexamethasone) or ≥ 60 mL/min (n=205, pomalidomide + low-dose dexamethasone; n=93, high-dose dexamethasone). Median progression-free survival was similar for both subgroups and favored pomalidomide + low-dose dexamethasone versus high-dose dexamethasone: 4.0 versus 1.9 months in the group with baseline creatinine clearance ≥ 30 − < 60 mL/min (P<0.001) and 4.0 versus 2.0 months in the group with baseline creatinine clearance ≥ 60 mL/min (P<0.001). Median overall survival for pomalidomide + low-dose dexamethasone versus high-dose dexamethasone was 10.4 versus 4.9 months (P=0.030) and 15.5 versus 9.2 months (P=0.133), respectively. Improved renal function, defined as an increase in creatinine clearance from < 60 to ≥ 60 mL/min, was similar in pomalidomide + low-dose dexamethasone and high-dose dexamethasone patients (42% and 47%, respectively). Improvement in progression-free and overall survival in these patients was comparable with that in patients without renal impairment. There was no increase in discontinuations of therapy, dose modifications, and adverse events in patients with moderate renal impairment. Pomalidomide at a starting dose of 4 mg + low-dose dexamethasone is well tolerated in patients with refractory or relapsed and refractory multiple myeloma, and of comparable efficacy if moderate renal impairment is present. This trial was registered with clinicaltrials.gov identifier 01311687 and EudraCT identifier 2010-019820-30. PMID:27081177

  18. Low-dose megavoltage cone-beam computed tomography for lung tumors using a high-efficiency image receptor

    SciTech Connect

    Sillanpaa, Jussi; Chang Jenghwa; Mageras, Gikas; Yorke, Ellen; Arruda, Fernando De; Rosenzweig, Kenneth E.; Munro, Peter; Seppi, Edward; Pavkovich, John; Amols, Howard

    2006-09-15

    We report on the capabilities of a low-dose megavoltage cone-beam computed tomography (MV CBCT) system. The high-efficiency image receptor consists of a photodiode array coupled to a scintillator composed of individual CsI crystals. The CBCT system uses the 6 MV beam from a linear accelerator. A synchronization circuit allows us to limit the exposure to one beam pulse [0.028 monitor units (MU)] per projection image. 150-500 images (4.2-13.9 MU total) are collected during a one-minute scan and reconstructed using a filtered backprojection algorithm. Anthropomorphic and contrast phantoms are imaged and the contrast-to-noise ratio of the reconstruction is studied as a function of the number of projections and the error in the projection angles. The detector dose response is linear (R{sup 2} value 0.9989). A 2% electron density difference is discernible using 460 projection images and a total exposure of 13 MU (corresponding to a maximum absorbed dose of about 12 cGy in a patient). We present first patient images acquired with this system. Tumors in lung are clearly visible and skeletal anatomy is observed in sufficient detail to allow reproducible registration with the planning kV CT images. The MV CBCT system is shown to be capable of obtaining good quality three-dimensional reconstructions at relatively low dose and to be clinically usable for improving the accuracy of radiotherapy patient positioning.

  19. Model-based iterative reconstruction and adaptive statistical iterative reconstruction: dose-reduced CT for detecting pancreatic calcification

    PubMed Central

    Katsura, Masaki; Akahane, Masaaki; Sato, Jiro; Matsuda, Izuru; Ohtomo, Kuni

    2016-01-01

    Background Iterative reconstruction methods have attracted attention for reducing radiation doses in computed tomography (CT). Purpose To investigate the detectability of pancreatic calcification using dose-reduced CT reconstructed with model-based iterative construction (MBIR) and adaptive statistical iterative reconstruction (ASIR). Material and Methods This prospective study approved by Institutional Review Board included 85 patients (57 men, 28 women; mean age, 69.9 years; mean body weight, 61.2 kg). Unenhanced CT was performed three times with different radiation doses (reference-dose CT [RDCT], low-dose CT [LDCT], ultralow-dose CT [ULDCT]). From RDCT, LDCT, and ULDCT, images were reconstructed with filtered-back projection (R-FBP, used for establishing reference standard), ASIR (L-ASIR), and MBIR and ASIR (UL-MBIR and UL-ASIR), respectively. A lesion (pancreatic calcification) detection test was performed by two blinded radiologists with a five-point certainty level scale. Results Dose-length products of RDCT, LDCT, and ULDCT were 410, 97, and 36 mGy-cm, respectively. Nine patients had pancreatic calcification. The sensitivity for detecting pancreatic calcification with UL-MBIR was high (0.67–0.89) compared to L-ASIR or UL-ASIR (0.11–0.44), and a significant difference was seen between UL-MBIR and UL-ASIR for one reader (P = 0.014). The area under the receiver-operating characteristic curve for UL-MBIR (0.818–0.860) was comparable to that for L-ASIR (0.696–0.844). The specificity was lower with UL-MBIR (0.79–0.92) than with L-ASIR or UL-ASIR (0.96–0.99), and a significant difference was seen for one reader (P < 0.01). Conclusion In UL-MBIR, pancreatic calcification can be detected with high sensitivity, however, we should pay attention to the slightly lower specificity. PMID:27110389

  20. Chemotherapy with or without low-dose interleukin-2 in advanced non-small cell lung cancer: results from a phase III randomized multicentric trial.

    PubMed

    Ridolfi, Laura; Bertetto, Oscar; Santo, Antonio; Naglieri, Emanuele; Lopez, Massimo; Recchia, Francesco; Lissoni, Paolo; Galliano, Marco; Testore, Franco; Porta, Camillo; Maglie, Monica; Dall'agata, Monia; Fumagalli, Luca; Ridolfi, Ruggero

    2011-10-01

    Non-small cell lung cancer (NSCLC) is associated with IL-2-dependent cell-mediated immunodeficiency. As IL-2 is the main lymphocyte growth factor, a phase III randomized multicenter trial was conducted to evaluate the impact of subcutaneous low-dose IL-2 added to standard chemotherapy (CT) on overall survival (OS) in advanced NSCLC patients. Patients (n=241) with histologically confirmed stage IIIb or IV non-operable NSCLC underwent stratified randomization on the basis of center, ECOG PS, stage of disease and percentage of weight loss. Patients received gemcitabine (1000 mg/m2) on days 1 and 8 + cisplatin (100 mg/m2) on day 2 every 21 days for a maximum of 6 cycles [chemotherapy (CT) arm]. In the CT+IL-2 arm, patients also received low-dose subcutaneous IL-2 3,000,000 IU/die on days 3-5, 9-11, 15-17. The study had 90% power to detect a 20% absolute increase in 1-year OS with 118 patients/arm. An overall response (OR) rate of 12.8% (14% in the CT+IL-2 arm and 11.4% in CT arm) was observed. Stable disease was 70 and 66.7%, and progressive disease 16 and 21.8% in the CT+IL-2 and CT arms, respectively. No differences in response were found in any subgroup analysis. At a median follow-up of 32 months, 1-year OS was 45% for the CT+IL-2 arm vs. 51% for the CT arm (p=0.456 log-rank). Median progression-free survival was 6.6 months in the CT+IL-2 arm vs. 6.9 months in the CT arm (p=0.573, log-rank). A higher number of grade 4 toxicities were reported with CT+IL-2. The most common grade ≥3 adverse events were gastrointestinal toxicity (mainly nausea and diarrhea) and myelosuppression. No relevant differences in clinical outcome were observed from the addition of IL-2 to CT. Future studies investigating the role of T-regulators in chemoimmunotherapeutic regimens could be performed. PMID:21720704

  1. Risk of Low Dose/Low Dose Rate Ionizing Radiation to Humans Symposium at the EMS 2009 Annual Meeting - September 2006

    SciTech Connect

    Morgan, William F.; von Borstel, Robert C.; Brenner, David; Redpath, J. Leslie; Erickson, Barbra E.; Brooks, Antone L.

    2009-11-12

    The low dose symposium thoughtfully addressed controversy of risk from low dose radiation exposure, hormesis and radon therapy. The stem cell symposium cogently considered the role of DNA damage and repair in hematopoietic stem cells underlying aging and malignancy and provocatively presented evidence that stem cells may have distinct morphologies and replicative properties, as well as special roles in cancer initiation. In the epigenetics symposium, studies illustrated the long range interaction of epigenetic mechanisms, the roles of CTCF and BORIS in region/specific regulation of epigenetic processes, the impact of DNA damage on epigenetic processes as well as links between epigenetic mechanisms and early nutrition and bystander effects.

  2. Beneficial effects of low dose radiation in response to the oncogenic KRAS induced cellular transformation.

    PubMed

    Kim, Rae-Kwon; Kim, Min-Jung; Seong, Ki Moon; Kaushik, Neha; Suh, Yongjoon; Yoo, Ki-Chun; Cui, Yan-Hong; Jin, Young Woo; Nam, Seon Young; Lee, Su-Jae

    2015-01-01

    Recently low dose irradiation has gained attention in the field of radiotherapy. For lack of understanding of the molecular consequences of low dose irradiation, there is much doubt concerning its risks on human beings. In this article, we report that low dose irradiation is capable of blocking the oncogenic KRAS-induced malignant transformation. To address this hypothesis, we showed that low dose irradiation, at doses of 0.1 Gray (Gy); predominantly provide defensive response against oncogenic KRAS -induced malignant transformation in human cells through the induction of antioxidants without causing cell death and acts as a critical regulator for the attenuation of reactive oxygen species (ROS). Importantly, we elucidated that knockdown of antioxidants significantly enhanced ROS generation, invasive and migratory properties and abnormal acini formation in KRAS transformed normal as well as cancer cells. Taken together, this study demonstrates that low dose irradiation reduces the KRAS induced malignant cellular transformation through diminution of ROS. This interesting phenomenon illuminates the beneficial effects of low dose irradiation, suggesting one of contributory mechanisms for reducing the oncogene induced carcinogenesis that intensify the potential use of low dose irradiation as a standard regimen. PMID:26515758

  3. Cost-effectiveness analysis of lung cancer screening with low-dose computerised tomography of the chest in Poland

    PubMed Central

    Szczęsny, Tomasz J.; Krysiński, Jerzy; Buciński, Adam; Kowalewski, Janusz; Pawłowicz, Zbigniew

    2015-01-01

    Aim of the study To determine the cost-effectiveness of lung cancer (LC) screening with low-dose computerised tomography of the chest, as compared to an approach without screening, reimbursed today by the National Health Fund (NHF) in Poland. Material and methods In order to analyse the current costs of diagnostic and therapeutic procedures of a model LC patient treated today, a model group consisting of 199 consecutive patients diagnosed and treated in the Oncology Centre in Bydgoszcz, Poland from January 2007 to April 2010 was used. The number and type of performed procedures in this group was obtained from the Polish Register of Neoplasms and the NHF. Only direct medical costs were analysed. To calculate the total costs of screening, diagnostics, and treatment of the hypothetical LC patient who would have cancer diagnosed with screening CT, data from the literature and costs calculated for the model group were used. Prices of procedures were obtained from the price list of the NHF on 30 April 2010 and did not change from that time until June 2014. One-way sensitivity analysis was performed. Results The average cost per LC patient, diagnosed and treated without screening, is 5567.50 EUR, and median LC-specific survival is one year. In the hypothetical LC patient with cancer diagnosed by screening, the average cost is 13689.35 EUR per LC patient, with a median LC-specific survival of at least seven years. A calculated incremental cost-effectiveness ratio (ICER) is 1353.64 EUR/year of life gained. Conclusions Lung cancer screening with low-dose CT would be highly cost-effective in Poland. PMID:26843847

  4. The Inhibitory Effects of Low-Dose Ionizing Radiation in IgE-Mediated Allergic Responses

    PubMed Central

    Nam, Seon Young; Yang, Kwang Hee; Kim, Cha Soon; Lee, In Kyung; Kim, Ji Young

    2015-01-01

    Ionizing radiation has different biological effects according to dose and dose rate. In particular, the biological effect of low-dose radiation is unclear. Low-dose whole-body gamma irradiation activates immune responses in several ways. However, the effects and mechanism of low-dose radiation on allergic responses remain poorly understood. Previously, we reported that low-dose ionizing radiation inhibits mediator release in IgE-mediated RBL-2H3 mast cell activation. In this study, to have any physiological relevance, we investigated whether low-dose radiation inhibits allergic responses in activated human mast cells (HMC-1(5C6) and LAD2 cells), mouse models of passive cutaneous anaphylaxis and the late-phase cutaneous response. High-dose radiation induced cell death, but low-dose ionizing radiation of <0.5 Gy did not induce mast cell death. Low-dose ionizing radiation that did not induce cell death significantly suppressed mediator release from human mast cells (HMC-1(5C6) and LAD2 cells) that were activated by antigen-antibody reaction. To determine the inhibitory mechanism of mediator released by low-dose ionizing radiation, we examined the phosphorylation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, and protein kinase C, as well as the intracellular free Ca2+ concentration ([Ca2+]i). The phosphorylation of signaling molecules and [Ca2+]i following stimulation of FcεRI receptors was inhibited by low dose ionizing radiation. In agreement with its in vitro effect, ionizing radiation also significantly inhibited inflammatory cells infiltration, cytokine mRNA expression (TNF-α, IL-4, IL-13), and symptoms of passive cutaneous anaphylaxis reaction and the late-phase cutaneous response in anti-dinitrophenyl IgE-sensitized mice. These results indicate that ionizing radiation inhibits both mast cell-mediated immediate- and delayed-type allergic reactions in vivo and in vitro. PMID:26317642

  5. The Inhibitory Effects of Low-Dose Ionizing Radiation in IgE-Mediated Allergic Responses.

    PubMed

    Joo, Hae Mi; Kang, Su Jin; Nam, Seon Young; Yang, Kwang Hee; Kim, Cha Soon; Lee, In Kyung; Kim, Ji Young

    2015-01-01

    Ionizing radiation has different biological effects according to dose and dose rate. In particular, the biological effect of low-dose radiation is unclear. Low-dose whole-body gamma irradiation activates immune responses in several ways. However, the effects and mechanism of low-dose radiation on allergic responses remain poorly understood. Previously, we reported that low-dose ionizing radiation inhibits mediator release in IgE-mediated RBL-2H3 mast cell activation. In this study, to have any physiological relevance, we investigated whether low-dose radiation inhibits allergic responses in activated human mast cells (HMC-1(5C6) and LAD2 cells), mouse models of passive cutaneous anaphylaxis and the late-phase cutaneous response. High-dose radiation induced cell death, but low-dose ionizing radiation of <0.5 Gy did not induce mast cell death. Low-dose ionizing radiation that did not induce cell death significantly suppressed mediator release from human mast cells (HMC-1(5C6) and LAD2 cells) that were activated by antigen-antibody reaction. To determine the inhibitory mechanism of mediator released by low-dose ionizing radiation, we examined the phosphorylation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, and protein kinase C, as well as the intracellular free Ca2+ concentration ([Ca2+]i). The phosphorylation of signaling molecules and [Ca2+]i following stimulation of FcεRI receptors was inhibited by low dose ionizing radiation. In agreement with its in vitro effect, ionizing radiation also significantly inhibited inflammatory cells infiltration, cytokine mRNA expression (TNF-α, IL-4, IL-13), and symptoms of passive cutaneous anaphylaxis reaction and the late-phase cutaneous response in anti-dinitrophenyl IgE-sensitized mice. These results indicate that ionizing radiation inhibits both mast cell-mediated immediate- and delayed-type allergic reactions in vivo and in vitro. PMID:26317642

  6. Evaluation of Enhanced Low Dose Rate Sensitivity in Discrete Bipolar Junction Transistors

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; Ladbury Raymond; LaBel, Kenneth; Topper, Alyson; Ladbury, Raymond; Triggs, Brian; Kazmakites, Tony

    2012-01-01

    We evaluate the low dose rate sensitivity in several families of discrete bipolar transistors across device parameter, quality assurance level, and irradiation bias configuration. The 2N2222 showed the most significant low dose rate sensitivity, with low dose rate enhancement factor of 3.91 after 100 krad(Si). The 2N2907 also showed critical degradation levels. The devices irradiated at 10 mrad(Si)/s exceeded specifications after 40 and 50 krad(Si) for the 2N2222 and 2N2907 devices, respectively.

  7. Extrapyramidal side-effects of low-dose aripiprazole in an 11-year-old child.

    PubMed

    Mohapatra, Satyakam

    2016-01-01

    Partial agonism of D2 and 5-HT1A receptors accounts for the low incidence of extrapyramidal side-effects of aripiprazole. Extrapyramidal symptoms (EPS) during treatment with therapeutical doses of aripiprazole have been reported in adults and children. To the best of our knowledge, no cases of EPS with low doses (5 mg) have been reported until now. In this article, we present an 11-year-old child who developed EPS on low doses (5 mg) aripiprazole. This case emphasizes the need for careful surveillance for the development of EPS in patients treated even with low doses of aripiprazole. PMID:26933364

  8. Enhanced Low Dose Rate Effects in Bipolar Circuits: A New Hardness Assurance Problem for NASA

    NASA Technical Reports Server (NTRS)

    Johnston, A.; Barnes, C.

    1995-01-01

    Many bipolar integrated circuits are much more susceptible to ionizing radiation at low dose rates than they are at high dose rates typically used for radiation parts testing. Since the low dose rate is equivalent to that seen in space, the standard lab test no longer can be considered conservative and has caused the Air Force to issue an alert. Although a reliable radiation hardness assurance test has not yet been designed, possible mechanisms for low dose rate enhancement and hardness assurance tests are discussed.

  9. Changes in thyroid status of rats after prolonged exposure to low dose dichlorodiphenyltrichloroethane.

    PubMed

    Yaglova, N V; Yaglov, V V

    2014-04-01

    The effect of low dose dichlorodiphenyltrichloroethane (DDT), omnipresent ecotoxicant and endocrine disruptor, on the functioning of the endocrine system is an urgent problem. We studied the effect of low dose DDT on thyroid status in rats. Rats receiving DDT in a dose of 1.890±0.086 μg/kg for 6 weeks showed increased concentrations of thyroid hormones, particularly triiodothyronine, and reduced level of thyrotropin. Longer exposure reduced the production of thyroid hormones. The dynamics of thyroid status parameters during DDT treatment in a low dose was similar to changes observed during the development of hypothyroidism induced by iodine deficiency. PMID:24824690

  10. Extrapyramidal side-effects of low-dose aripiprazole in an 11-year-old child

    PubMed Central

    Mohapatra, Satyakam

    2016-01-01

    Partial agonism of D2 and 5-HT1A receptors accounts for the low incidence of extrapyramidal side-effects of aripiprazole. Extrapyramidal symptoms (EPS) during treatment with therapeutical doses of aripiprazole have been reported in adults and children. To the best of our knowledge, no cases of EPS with low doses (5 mg) have been reported until now. In this article, we present an 11-year-old child who developed EPS on low doses (5 mg) aripiprazole. This case emphasizes the need for careful surveillance for the development of EPS in patients treated even with low doses of aripiprazole. PMID:26933364

  11. Modeling Low-Dose-Rate Effects in Irradiated Bipolar-Base Oxides

    SciTech Connect

    Cirba, C.R.; Fleetwood, D.M.; Graves, R.J.; Michez, A.; Milanowski, R.J.; Saigne, F.; Schrimpf, R.D.; Witczak, S.C.

    1998-10-26

    A physical model is developed to quantify the contribution of oxide-trapped charge to enhanced low-dose-rate gain degradation in bipolar junction transistors. Multiple-trapping simulations show that space charge limited transport is partially responsible for low-dose-rate enhancement. At low dose rates, more holes are trapped near the silicon-oxide interface than at high dose rates, resulting in larger midgap voltage shifts at lower dose rates. The additional trapped charge near the interface may cause an exponential increase in excess base current, and a resultant decrease in current gain for some NPN bipolar technologies.

  12. SU-C-207-05: A Comparative Study of Noise-Reduction Algorithms for Low-Dose Cone-Beam Computed Tomography

    SciTech Connect

    Mukherjee, S; Yao, W

    2015-06-15

    Purpose: To study different noise-reduction algorithms and to improve the image quality of low dose cone beam CT for patient positioning in radiation therapy. Methods: In low-dose cone-beam CT, the reconstructed image is contaminated with excessive quantum noise. In this study, three well-developed noise reduction algorithms namely, a) penalized weighted least square (PWLS) method, b) split-Bregman total variation (TV) method, and c) compressed sensing (CS) method were studied and applied to the images of a computer–simulated “Shepp-Logan” phantom and a physical CATPHAN phantom. Up to 20% additive Gaussian noise was added to the Shepp-Logan phantom. The CATPHAN phantom was scanned by a Varian OBI system with 100 kVp, 4 ms and 20 mA. For comparing the performance of these algorithms, peak signal-to-noise ratio (PSNR) of the denoised images was computed. Results: The algorithms were shown to have the potential in reducing the noise level for low-dose CBCT images. For Shepp-Logan phantom, an improvement of PSNR of 2 dB, 3.1 dB and 4 dB was observed using PWLS, TV and CS respectively, while for CATPHAN, the improvement was 1.2 dB, 1.8 dB and 2.1 dB, respectively. Conclusion: Penalized weighted least square, total variation and compressed sensing methods were studied and compared for reducing the noise on a simulated phantom and a physical phantom scanned by low-dose CBCT. The techniques have shown promising results for noise reduction in terms of PSNR improvement. However, reducing the noise without compromising the smoothness and resolution of the image needs more extensive research.

  13. Dual-Energy CT: Spectrum of Thoracic Abnormalities.

    PubMed

    Otrakji, Alexi; Digumarthy, Subba R; Lo Gullo, Roberto; Flores, Efren J; Shepard, Jo-Anne O; Kalra, Mannudeep K

    2016-01-01

    Recent studies have demonstrated that dual-energy computed tomography (CT) can provide useful information in several chest-related clinical indications. Compared with single-energy CT, dual-energy CT of the chest is feasible with the use of a radiation-dose-neutral scanning protocol. This article highlights the different types of images that can be generated by using dual-energy CT protocols such as virtual monochromatic, virtual unenhanced (ie, water), and pulmonary blood volume (ie, iodine) images. The physical basis of dual-energy CT and material decomposition are explained. The advantages of the use of virtual low-monochromatic images include reduced volume of intravenous contrast material and improved contrast resolution of images. The use of virtual high-monochromatic images can reduce beam hardening and contrast streak artifacts. The pulmonary blood volume images can help differentiate various parenchymal abnormalities, such as infarcts, atelectasis, and pneumonias, as well as airway abnormalities. The pulmonary blood volume images allow quantitative and qualitative assessment of iodine distribution. The estimation of iodine concentration (quantitative assessment) provides objective analysis of enhancement. The advantages of virtual unenhanced images include differentiation of calcifications, talc, and enhanced thoracic structures. Dual-energy CT has applications in oncologic imaging, including diagnosis of thoracic masses, treatment planning, and assessment of response to treatment. Understanding the concept of dual-energy CT and its clinical application in the chest are the goals of this article. PMID:26761530

  14. Low Dose Dopamine or Low Dose Nesiritide in Acute Heart Failure with Renal Dysfunction: The ROSE Acute Heart Failure Randomized Trial

    PubMed Central

    Chen, Horng H.; Anstrom, Kevin J.; Givertz, Michael M.; Stevenson, Lynne W.; Semigran, Marc J.; Goldsmith, Steven R.; Bart, Bradley A.; Bull, David A.; Stehlik, Josef; LeWinter, Martin M.; Konstam, Marvin A.; Huggins, Gordon S.; Rouleau, Jean L.; O’Meara, Eileen; Tang, W.H. Wilson; Starling, Randall C.; Butler, Javed; Deswal, Anita; Felker, G. Michael; O’Connor, Christopher M.; Bonita, Raphael E.; Margulies, Kenneth B.; Cappola, Thomas P.; Ofili, Elizabeth O.; Mann, Douglas L.; Dávila-Román, Víctor G.; McNulty, Steven E.; Borlaug, Barry A.; Velazquez, Eric J.; Lee, Kerry L.; Shah, Monica R.; Hernandez, Adrian F.; Braunwald, Eugene; Redfield, Margaret M.

    2014-01-01

    Importance Small studies suggest low dose dopamine or low dose nesiritide may enhance decongestion and preserve renal function in patients with acute heart failure and renal dysfunction; however, neither strategy has been rigorously tested. Objective To test the two independent hypotheses that when compared to placebo, addition of: (1) low dose dopamine (2 ug/kg/min); or (2) low dose nesiritide (0.005 ug/kg/min without bolus) to diuretic therapy will enhance decongestion and preserve renal function in patients with acute heart failure and renal dysfunction. Design, Setting and Participants Multicenter, double-blind, placebo-controlled randomized clinical trial (Renal Optimization Strategies Evaluation) of 360 hospitalized participants with acute heart failure and renal dysfunction (estimated glomerular filtration rate of 15–60 ml/min/1.73m2), randomized within 24 hours of admission. Participants were randomized from September 2010 to March 2013 across 26 sites in the United States and Canada. Interventions Participants were randomized in an open, 1:1 allocation ratio to the dopamine or nesiritide strategies. Within each strategy, participants were randomized in a double-blind, 2:1 ratio to active treatment or placebo. The dopamine (n=122) and nesiritide (n=119) groups were independently compared to the pooled placebo group (n=119). Main outcome measures Co-primary endpoints included 72-hour cumulative urine volume (decongestion endpoint) and the change in serum cystatin-C from enrollment to 72 hours (renal function endpoint). Results Compared to placebo, low dose dopamine had no significant effect on 72-hour cumulative urine volume (8524 ml [95% CI 7917 to 9131 ml] with dopamine vs. 8296 ml [95% CI 7762 to 8830 ml] with placebo, p=0.59) or on the change in cystatin-C (0.12 mg/L [95% CI 0.06 to 0.18 mg/L] with dopamine vs. 0.11 mg/L [95% CI 0.06 to 0.16 mg/L] with placebo, p=0.72). Similarly, low dose nesiritide had no significant effect on 72-hour cumulative

  15. Enhanced charge trapping in bipolar spacer oxides during low-dose-rate irradiation

    SciTech Connect

    Fleetwood, D.M.; Reber, R.A. Jr.; Winokur, P.S.; Kosier, S.L.; Schrimpf, R.D.; Nowlin, R.N.; Pease, R.L.; DeLaus, M.

    1994-03-01

    Thermally-stimulated-current and capacitance-voltage measurements reveal enhanced hole trapping in bipolar spacer-oxide capacitors irradiated at 0 V at low dose rates. Possible mechanisms and implications for bipolar low-rate response are discussed.

  16. The impact of low-dose carcinogens and environmental disruptors on tissue invasion and metastasis

    PubMed Central

    Ochieng, Josiah; Nangami, Gladys N.; Ogunkua, Olugbemiga; Miousse, Isabelle R.; Koturbash, Igor; Odero-Marah, Valerie; McCawley, Lisa; Nangia-Makker, Pratima; Ahmed, Nuzhat; Luqmani, Yunus; Chen, Zhenbang; Papagerakis, Silvana; Wolf, Gregory T.; Dong, Chenfang; Zhou, Binhua P.; Brown, Dustin G.; Colacci, Annamaria; Hamid, Roslida A.; Mondello, Chiara; Raju, Jayadev; Ryan, Elizabeth P.; Woodrick, Jordan; Scovassi, Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Salem, Hosni K.; Amedei, Amedeo; Al-Temaimi, Rabeah; Al-Mulla, Fahd; Bisson, William H.; Eltom, Sakina E.

    2015-01-01

    The purpose of this review is to stimulate new ideas regarding low-dose environmental mixtures and carcinogens and their potential to promote invasion and metastasis. Whereas a number of chapters in this review are devoted to the role of low-dose environmental mixtures and carcinogens in the promotion of invasion and metastasis in specific tumors such as breast and prostate, the overarching theme is the role of low-dose carcinogens in the progression of cancer stem cells. It is becoming clearer that cancer stem cells in a tumor are the ones that assume invasive properties and colonize distant organs. Therefore, low-dose contaminants that trigger epithelial–mesenchymal transition, for example, in these cells are of particular interest in this review. This we hope will lead to the collaboration between scientists who have dedicated their professional life to the study of carcinogens and those whose interests are exclusively in the arena of tissue invasion and metastasis. PMID:26106135

  17. Low-Dose Radioactive Iodine Destroys Thyroid Tissue Left after Surgery

    Cancer.gov

    A low dose of radioactive iodine given after surgery for thyroid cancer destroyed (ablated) residual thyroid tissue as effectively as a higher dose, with fewer side effects and less exposure to radiation, according to two randomized controlled trials.

  18. Effects of physicochemical forms of phenazepam and Panavir on their action at ultra-low doses.

    PubMed

    Stovbun, S V; Kiselev, A V; Zanin, A M; Kalinina, T S; Voronina, T A; Mikhailov, A I; Berlin, A A

    2012-08-01

    A concept of physicochemical forms of biologically active substances introduced in investigation of the action mechanism of ultra-low doses allows qualitative explanation of the main effects of ultra-low doses, chemical diversity of biologically active substances, and physical boundaries for these effects. Phenazepam was shown to possess activity in ultra-low doses only in disperse state, in the form of nanoparticles with a diameter <100-300 nm; these nanoparticles appear as micelles of surface active substances and solvated. Panavir possesses pharmacological activity in ultra-low doses and appears as nanoparticles with a diameter of 200-300 nm, which have uncompensated negative surface charge and polymer nature. PMID:22977843

  19. Low-dose radiation exposure induces a HIF-1-mediated adaptive and protective metabolic response

    PubMed Central

    Lall, R; Ganapathy, S; Yang, M; Xiao, S; Xu, T; Su, H; Shadfan, M; Asara, J M; Ha, C S; Ben-Sahra, I; Manning, B D; Little, J B; Yuan, Z-M

    2014-01-01

    Because of insufficient understanding of the molecular effects of low levels of radiation exposure, there is a great uncertainty regarding its health risks. We report here that treatment of normal human cells with low-dose radiation induces a metabolic shift from oxidative phosphorylation to aerobic glycolysis resulting in increased radiation resistance. This metabolic change is highlighted by upregulation of genes encoding glucose transporters and enzymes of glycolysis and the oxidative pentose phosphate pathway, concomitant with downregulation of mitochondrial genes, with corresponding changes in metabolic flux through these pathways. Mechanistically, the metabolic reprogramming depends on HIF1α, which is induced specifically by low-dose irradiation linking the metabolic pathway with cellular radiation dose response. Increased glucose flux and radiation resistance from low-dose irradiation are also observed systemically in mice. This highly sensitive metabolic response to low-dose radiation has important implications in understanding and assessing the health risks of radiation exposure. PMID:24583639

  20. The impact of low-dose carcinogens and environmental disruptors on tissue invasion and metastasis.

    PubMed

    Ochieng, Josiah; Nangami, Gladys N; Ogunkua, Olugbemiga; Miousse, Isabelle R; Koturbash, Igor; Odero-Marah, Valerie; McCawley, Lisa J; Nangia-Makker, Pratima; Ahmed, Nuzhat; Luqmani, Yunus; Chen, Zhenbang; Papagerakis, Silvana; Wolf, Gregory T; Dong, Chenfang; Zhou, Binhua P; Brown, Dustin G; Colacci, Anna Maria; Hamid, Roslida A; Mondello, Chiara; Raju, Jayadev; Ryan, Elizabeth P; Woodrick, Jordan; Scovassi, A Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Salem, Hosni K; Amedei, Amedeo; Al-Temaimi, Rabeah; Al-Mulla, Fahd; Bisson, William H; Eltom, Sakina E

    2015-06-01

    The purpose of this review is to stimulate new ideas regarding low-dose environmental mixtures and carcinogens and their potential to promote invasion and metastasis. Whereas a number of chapters in this review are devoted to the role of low-dose environmental mixtures and carcinogens in the promotion of invasion and metastasis in specific tumors such as breast and prostate, the overarching theme is the role of low-dose carcinogens in the progression of cancer stem cells. It is becoming clearer that cancer stem cells in a tumor are the ones that assume invasive properties and colonize distant organs. Therefore, low-dose contaminants that trigger epithelial-mesenchymal transition, for example, in these cells are of particular interest in this review. This we hope will lead to the collaboration between scientists who have dedicated their professional life to the study of carcinogens and those whose interests are exclusively in the arena of tissue invasion and metastasis. PMID:26106135

  1. The estimation of low-dose hazards by extrapolation from high doses.

    PubMed

    Rossi, H H

    1981-01-01

    Empirical information on the effects of low doses of ionizing radiation is beset by severe limitations. Theoretical considerations of biophysics can guide the analysis of epidemiological data by indicating certain dose-response relations or eliminating others. Thus, it can be shown that at low doses there must be proportionality between dose and effect on non-interacting cells and that one must anticipate different dose-effect relations upon exposure to markedly different types of radiation. PMID:7336764

  2. Modeling low-dose mortality and disease incubation period of inhalational anthrax in the rabbit.

    PubMed

    Gutting, Bradford W; Marchette, David; Sherwood, Robert; Andrews, George A; Director-Myska, Alison; Channel, Stephen R; Wolfe, Daniel; Berger, Alan E; Mackie, Ryan S; Watson, Brent J; Rukhin, Andrey

    2013-07-21

    There is a need to advance our ability to conduct credible human risk assessments for inhalational anthrax associated with exposure to a low number of bacteria. Combining animal data with computational models of disease will be central in the low-dose and cross-species extrapolations required in achieving this goal. The objective of the current work was to apply and advance the competing risks (CR) computational model of inhalational anthrax where data was collected from NZW rabbits exposed to aerosols of Ames strain Bacillus anthracis. An initial aim was to parameterize the CR model using high-dose rabbit data and then conduct a low-dose extrapolation. The CR low-dose attack rate was then compared against known low-dose rabbit data as well as the low-dose curve obtained when the entire rabbit dose-response data set was fitted to an exponential dose-response (EDR) model. The CR model predictions demonstrated excellent agreement with actual low-dose rabbit data. We next used a modified CR model (MCR) to examine disease incubation period (the time to reach a fever >40 °C). The MCR model predicted a germination period of 14.5h following exposure to a low spore dose, which was confirmed by monitoring spore germination in the rabbit lung using PCR, and predicted a low-dose disease incubation period in the rabbit between 14.7 and 16.8 days. Overall, the CR and MCR model appeared to describe rabbit inhalational anthrax well. These results are discussed in the context of conducting laboratory studies in other relevant animal models, combining the CR/MCR model with other computation models of inhalational anthrax, and using the resulting information towards extrapolating a low-dose response prediction for man. PMID:23567649

  3. Cytogenetic Low-Dose Hyperradiosensitivity Is Observed in Human Peripheral Blood Lymphocytes

    SciTech Connect

    Seth, Isheeta; Joiner, Michael C.; Tucker, James D.

    2015-01-01

    Purpose: The shape of the ionizing radiation response curve at very low doses has been the subject of considerable debate. Linear-no-threshold (LNT) models are widely used to estimate risks associated with low-dose exposures. However, the low-dose hyperradiosensitivity (HRS) phenomenon, in which cells are especially sensitive at low doses but then show increased radioresistance at higher doses, provides evidence of nonlinearity in the low-dose region. HRS is more prominent in the G2 phase of the cell cycle than in the G0/G1 or S phases. Here we provide the first cytogenetic mechanistic evidence of low-dose HRS in human peripheral blood lymphocytes using structural chromosomal aberrations. Methods and Materials: Human peripheral blood lymphocytes from 2 normal healthy female donors were acutely exposed to cobalt 60 γ rays in either G0 or G2 using closely spaced doses ranging from 0 to 1.5 Gy. Structural chromosomal aberrations were enumerated, and the slopes of the regression lines at low doses (0-0.4 Gy) were compared with doses of 0.5 Gy and above. Results: HRS was clearly evident in both donors for cells irradiated in G2. No HRS was observed in cells irradiated in G0. The radiation effect per unit dose was 2.5- to 3.5-fold higher for doses ≤0.4 Gy than for doses >0.5 Gy. Conclusions: These data provide the first cytogenetic evidence for the existence of HRS in human cells irradiated in G2 and suggest that LNT models may not always be optimal for making radiation risk assessments at low doses.

  4. Radon Exposure and the Definition of Low Doses-The Problem of Spatial Dose Distribution.

    PubMed

    Madas, Balázs G

    2016-07-01

    Investigating the health effects of low doses of ionizing radiation is considered to be one of the most important fields in radiological protection research. Although the definition of low dose given by a dose range seems to be clear, it leaves some open questions. For example, the time frame and the target volume in which absorbed dose is measured have to be defined. While dose rate is considered in the current system of radiological protection, the same cancer risk is associated with all exposures, resulting in a given amount of energy absorbed by a single target cell or distributed among all the target cells of a given organ. However, the biological effects and so the health consequences of these extreme exposure scenarios are unlikely to be the same. Due to the heterogeneous deposition of radon progeny within the lungs, heterogeneous radiation exposure becomes a practical issue in radiological protection. While the macroscopic dose is still within the low dose range, local tissue doses on the order of Grays can be reached in the most exposed parts of the bronchial airways. It can be concluded that progress in low dose research needs not only low dose but also high dose experiments where small parts of a biological sample receive doses on the order of Grays, while the average dose over the whole sample remains low. A narrow interpretation of low dose research might exclude investigations with high relevance to radiological protection. Therefore, studies important to radiological protection should be performed in the frame of low dose research even if the applied doses do not fit in the dose range used for the definition of low doses. PMID:27218294

  5. Safety of low dose glucocorticoid treatment in rheumatoid arthritis: published evidence and prospective trial data

    PubMed Central

    Da Silva, J A P; Jacobs, J W G; Kirwan, J R; Boers, M; Saag, K G; Inês, L B S; de Koning, E J P; Buttgereit, F; Cutolo, M; Capell, H; Rau, R; Bijlsma, J W J

    2006-01-01

    Adverse effects of glucocorticoids have been abundantly reported. Published reports on low dose glucocorticoid treatment show that few of the commonly held beliefs about their incidence, prevalence, and impact are supported by clear scientific evidence. Safety data from recent randomised controlled clinical trials of low dose glucocorticoid treatment in RA suggest that adverse effects associated with this drug are modest, and often not statistically different from those of placebo. PMID:16107513

  6. Pulsed low-dose RANKL as a potential therapeutic for postmenopausal osteoporosis

    PubMed Central

    Cline-Smith, Anna; Gibbs, Jesse; Shashkova, Elena; Buchwald, Zachary S.; Novack, Deborah V.; Aurora, Rajeev

    2016-01-01

    A number of studies in model animal systems and in the clinic have established that RANKL promotes bone resorption. Paradoxically, we found that pulsing ovariectomized mice with low-dose RANKL suppressed bone resorption, decreased the levels of proinflammatory effector T cells and led to increased bone mass. This effect of RANKL is mediated through the induction of FoxP3+CD25+ regulatory CD8+ T cells (TcREG) by osteoclasts. Here, we show that pulses of low-dose RANKL are needed to induce TcREG, as continuous infusion of identical doses of RANKL by pump did not induce TcREG. We also show that low-dose RANKL can induce TcREG at 2, 3, 6, and 10 weeks after ovariectomy. Our results show that low-dose RANKL treatment in ovariectomized mice is optimal at once-per-month doses to maintain the bone mass. Finally, we found that treatment of ovariectomized mice with the Cathepsin K inhibitor odanacatib also blocked TcREG induction by low-dose RANKL. We interpret this result to indicate that antigens presented to CD8+ T cells by osteoclasts are derived from the bone protein matrix because Cathepsin K degrades collagen in the bone. Taken together, our studies provide a basis for using low-dose RANKL as a potential therapeutic for postmenopausal osteoporosis. PMID:27570837

  7. Super-low Dose Endotoxin Pre-conditioning Exacerbates Sepsis Mortality

    PubMed Central

    Chen, Keqiang; Geng, Shuo; Yuan, Ruoxi; Diao, Na; Upchurch, Zachary; Li, Liwu

    2015-01-01

    Sepsis mortality varies dramatically in individuals of variable immune conditions, with poorly defined mechanisms. This phenomenon complements the hypothesis that innate immunity may adopt rudimentary memory, as demonstrated in vitro with endotoxin priming and tolerance in cultured monocytes. However, previous in vivo studies only examined the protective effect of endotoxin tolerance in the context of sepsis. In sharp contrast, we report herein that pre-conditioning with super-low or low dose endotoxin lipopolysaccharide (LPS) cause strikingly opposite survival outcomes. Mice pre-conditioned with super-low dose LPS experienced severe tissue damage, inflammation, increased bacterial load in circulation, and elevated mortality when they were subjected to cecal-ligation and puncture (CLP). This is in contrast to the well-reported protective phenomenon with CLP mice pre-conditioned with low dose LPS. Mechanistically, we demonstrated that super-low and low dose LPS differentially modulate the formation of neutrophil extracellular trap (NET) in neutrophils. Instead of increased ERK activation and NET formation in neutrophils pre-conditioned with low dose LPS, we observed significantly reduced ERK activation and compromised NET generation in neutrophils pre-conditioned with super-low dose LPS. Collectively, our findings reveal a mechanism potentially responsible for the dynamic programming of innate immunity in vivo as it relates to sepsis risks. PMID:26029736

  8. Comparison of the Effects of Low-Dose Midazolam, Magnesium Sulfate, Remifentanil and Low-Dose Etomidate on Prevention of Etomidate-Induced Myoclonus in Orthopedic Surgeries

    PubMed Central

    Sedighinejad, Abbas; Naderi Nabi, Bahram; Haghighi, Mohammad; Biazar, Gelareh; Imantalab, Vali; Rimaz, Siamak; Zaridoost, Zahra

    2016-01-01

    Background Etomidate is a potent hypnotic agent with several desirable advantages such as providing a stable cardiovascular profile with minimal respiratory adverse effects and better hemodynamic stability compared with other induction agents. This drug is associated, however, with myoclonic movements which is characterized by a sudden, brief muscle contractions as a disturbing side-effect. Objectives The present study was designed to compare the effectiveness of low- dose midazolam, magnesium sulfate, remifentanil and low-dose etomidate to suppress etomidate-induced myoclonus in orthopedic surgery. Patients and Methods A double-blind clinical trial study was conducted in an academic hospital from September 2014 to August 2015. Two hundred and eighty-four eligible patients, American society of anesthesiologists class I - II, scheduled for elective orthopedic surgery were randomly allocated into four equal groups (n = 71). They received premedication with intravenous low-dose midazolam 0.015 mg/kg, magnesium sulfate 30 mg/kg, remifentanil 1 μg/kg and low-dose etomidate 0.03 mg/kg two minutes before induction of anesthesia with 0.3 mg/kg intravenous etomidate. Then the incidence and intensity of myoclonus were evaluated on a scale of 0 - 3; 0 = no myoclonus; 1 = mild (movement at wrist); 2 = moderate (movement at arm only, elbow or shoulder); and 3 = severe, generalized response or movement in more than one extremity, within ninety seconds. Any adverse effect due to these premedication agents was recorded. Results The incidence and intensity of myoclonus were significantly lower in the low-dose etomidate group. The incidence rates of myoclonus were 51 (71.85%), 61 (85.9%), 30 (42.3%) and 41 (57.7%), and the percentages of patients who experienced grade III of myoclonus were 30 (58.8%), 32 (52.5%), 9 (30%) and 14 (34.1%) in the midazolam, magnesium sulfate, etomidate and remifentanil groups, respectively. The incidence and intensity of myoclonus were significantly

  9. Effects of Low-Dose and Very Low-Dose Ketamine among Patients with Major Depression: a Systematic Review and Meta-Analysis

    PubMed Central

    Xu, Ying; Hackett, Maree; Carter, Gregory; Gálvez, Verònica; Glozier, Nick; Glue, Paul; Lapidus, Kyle; McGirr, Alexander; Somogyi, Andrew A.; Mitchell, Philip B.; Rodgers, Anthony

    2016-01-01

    Background: Several recent trials indicate low-dose ketamine produces rapid antidepressant effects. However, uncertainty remains in several areas: dose response, consistency across patient groups, effects on suicidality, and possible biases arising from crossover trials. Methods: A systematic search was conducted for relevant randomized trials in Medline, Embase, and PsycINFO databases up to August 2014. The primary endpoints were change in depression scale scores at days 1, 3 and 7, remission, response, suicidality, safety, and tolerability. Data were independently abstracted by 2 reviewers. Where possible, unpublished data were obtained on treatment effects in the first period of crossover trials. Results: Nine trials were identified, including 201 patients (52% female, mean age 46 years). Six trials assessed low-dose ketamine (0.5mg/kg i.v.) and 3 tested very low-dose ketamine (one trial assessed 50mg intra-nasal spray, another assessed 0.1–0.4mg/kg i.v., and another assessed 0.1–0.5mg/kg i.v., intramuscular, or s.c.). At day 3, the reduction in depression severity score was less marked in the very low-dose trials (P homogeneity <.05) and among bipolar patients. In analyses excluding the second period of crossover trials, response rates at day 7 were increased with ketamine (relative risk 3.4, 95% CI 1.6–7.1, P=.001), as were remission rates (relative risk 2.6, CI 1.2–5.7, P=.02). The absolute benefits were large, with day 7 remission rates of 24% vs 6% (P=.02). Seven trials provided unpublished data on suicidality item scores, which were reduced on days 1 and 3 (both P<.01) but not day 7. Conclusion: Low-dose ketamine appears more effective than very low dose. There is substantial heterogeneity in clinical response, with remission among one-fifth of patients at 1 week but most others having benefits that are less durable. Larger, longer term parallel group trials are needed to determine if efficacy can be extended and to further assess safety. PMID

  10. Low-dose cerebral perfusion computed tomography image restoration via low-rank and total variation regularizations

    PubMed Central

    Niu, Shanzhou; Zhang, Shanli; Huang, Jing; Bian, Zhaoying; Chen, Wufan; Yu, Gaohang; Liang, Zhengrong; Ma, Jianhua

    2016-01-01

    Cerebral perfusion x-ray computed tomography (PCT) is an important functional imaging modality for evaluating cerebrovascular diseases and has been widely used in clinics over the past decades. However, due to the protocol of PCT imaging with repeated dynamic sequential scans, the associative radiation dose unavoidably increases as compared with that used in conventional CT examinations. Minimizing the radiation exposure in PCT examination is a major task in the CT field. In this paper, considering the rich similarity redundancy information among enhanced sequential PCT images, we propose a low-dose PCT image restoration model by incorporating the low-rank and sparse matrix characteristic of sequential PCT images. Specifically, the sequential PCT images were first stacked into a matrix (i.e., low-rank matrix), and then a non-convex spectral norm/regularization and a spatio-temporal total variation norm/regularization were then built on the low-rank matrix to describe the low rank and sparsity of the sequential PCT images, respectively. Subsequently, an improved split Bregman method was adopted to minimize the associative objective function with a reasonable convergence rate. Both qualitative and quantitative studies were conducted using a digital phantom and clinical cerebral PCT datasets to evaluate the present method. Experimental results show that the presented method can achieve images with several noticeable advantages over the existing methods in terms of noise reduction and universal quality index. More importantly, the present method can produce more accurate kinetic enhanced details and diagnostic hemodynamic parameter maps. PMID:27440948

  11. Adaptive-weighted total variation minimization for sparse data toward low-dose x-ray computed tomography image reconstruction

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Ma, Jianhua; Fan, Yi; Liang, Zhengrong

    2012-12-01

    Previous studies have shown that by minimizing the total variation (TV) of the to-be-estimated image with some data and other constraints, piecewise-smooth x-ray computed tomography (CT) can be reconstructed from sparse-view projection data without introducing notable artifacts. However, due to the piecewise constant assumption for the image, a conventional TV minimization algorithm often suffers from over-smoothness on the edges of the resulting image. To mitigate this drawback, we present an adaptive-weighted TV (AwTV) minimization algorithm in this paper. The presented AwTV model is derived by considering the anisotropic edge property among neighboring image voxels, where the associated weights are expressed as an exponential function and can be adaptively adjusted by the local image-intensity gradient for the purpose of preserving the edge details. Inspired by the previously reported TV-POCS (projection onto convex sets) implementation, a similar AwTV-POCS implementation was developed to minimize the AwTV subject to data and other constraints for the purpose of sparse-view low-dose CT image reconstruction. To evaluate the presented AwTV-POCS algorithm, both qualitative and quantitative studies were performed by computer simulations and phantom experiments. The results show that the presented AwTV-POCS algorithm can yield images with several notable gains, in terms of noise-resolution tradeoff plots and full-width at half-maximum values, as compared to the corresponding conventional TV-POCS algorithm.

  12. LOW DOSE STUDIES WITH FOCUSED X-RAYS IN CELL AND TISSUE MODELS: MECHANISMS OF BYSTANDER AND GENOMIC INSTABILITY RESPONSES

    EPA Science Inventory

    The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept t...

  13. Hormones and Endocrine-Disrupting Chemicals: Low-Dose Effects and Nonmonotonic Dose Responses

    PubMed Central

    Colborn, Theo; Hayes, Tyrone B.; Heindel, Jerrold J.; Jacobs, David R.; Lee, Duk-Hee; Shioda, Toshi; Soto, Ana M.; vom Saal, Frederick S.; Welshons, Wade V.; Zoeller, R. Thomas

    2012-01-01

    For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of “the dose makes the poison,” because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health. PMID:22419778

  14. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses.

    PubMed

    Vandenberg, Laura N; Colborn, Theo; Hayes, Tyrone B; Heindel, Jerrold J; Jacobs, David R; Lee, Duk-Hee; Shioda, Toshi; Soto, Ana M; vom Saal, Frederick S; Welshons, Wade V; Zoeller, R Thomas; Myers, John Peterson

    2012-06-01

    For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health. PMID:22419778

  15. Low dose tomographic fluoroscopy: 4D intervention guidance with running prior

    SciTech Connect

    Flach, Barbara; Kuntz, Jan; Brehm, Marcus; Kachelrieß, Marc; Kueres, Rolf; Bartling, Sönke

    2013-10-15

    . Reconstructed volumes based on the running prior show high image quality without introducing new artifacts and the interventional materials are displayed at the correct position.Conclusions: The running prior improves the robustness of low dose 3D+T intervention guidance toward intended or unintended patient motion.

  16. Hemiablative Focal Low Dose Rate Brachytherapy: A Phase II Trial Protocol

    PubMed Central

    Bucci, Joseph; Chin, Yaw Sinn; Malouf, David; Howie, Andrew; Enari, Komiti Ese

    2016-01-01

    trial (RCT). Conclusions This protocol is designed to show feasibility in delivering hemigland focal therapy with seed BT. It may answer crucial questions and obtain data which will enable downstream decisions on focal low dose rate (LDR) prostate BT. ClinicalTrial Clinicaltrial.gov NCT02643511; https://www.clinicaltrials.gov/ct2/show/NCT02643511 (Archived by Webcite at http://www.webcitation.org/6ghLCzIhY) PMID:27296781

  17. Body-wide anatomy recognition in PET/CT images

    NASA Astrophysics Data System (ADS)

    Wang, Huiqian; Udupa, Jayaram K.; Odhner, Dewey; Tong, Yubing; Zhao, Liming; Torigian, Drew A.

    2015-03-01

    With the rapid growth of positron emission tomography/computed tomography (PET/CT)-based medical applications, body-wide anatomy recognition on whole-body PET/CT images becomes crucial for quantifying body-wide disease burden. This, however, is a challenging problem and seldom studied due to unclear anatomy reference frame and low spatial resolution of PET images as well as low contrast and spatial resolution of the associated low-dose CT images. We previously developed an automatic anatomy recognition (AAR) system [15] whose applicability was demonstrated on diagnostic computed tomography (CT) and magnetic resonance (MR) images in different body regions on 35 objects. The aim of the present work is to investigate strategies for adapting the previous AAR system to low-dose CT and PET images toward automated body-wide disease quantification. Our adaptation of the previous AAR methodology to PET/CT images in this paper focuses on 16 objects in three body regions - thorax, abdomen, and pelvis - and consists of the following steps: collecting whole-body PET/CT images from existing patient image databases, delineating all objects in these images, modifying the previous hierarchical models built from diagnostic CT images to account for differences in appearance in low-dose CT and PET images, automatically locating objects in these images following object hierarchy, and evaluating performance. Our preliminary evaluations indicate that the performance of the AAR approach on low-dose CT images achieves object localization accuracy within about 2 voxels, which is comparable to the accuracies achieved on diagnostic contrast-enhanced CT images. Object recognition on low-dose CT images from PET/CT examinations without requiring diagnostic contrast-enhanced CT seems feasible.

  18. Noise correlation in CBCT projection data and its application for noise reduction in low-dose CBCT

    SciTech Connect

    Zhang, Hua; Ouyang, Luo; Wang, Jing E-mail: jing.wang@utsouthwestern.edu; Ma, Jianhua E-mail: jing.wang@utsouthwestern.edu; Huang, Jing; Chen, Wufan

    2014-03-15

    Purpose: To study the noise correlation properties of cone-beam CT (CBCT) projection data and to incorporate the noise correlation information to a statistics-based projection restoration algorithm for noise reduction in low-dose CBCT. Methods: In this study, the authors systematically investigated the noise correlation properties among detector bins of CBCT projection data by analyzing repeated projection measurements. The measurements were performed on a TrueBeam onboard CBCT imaging system with a 4030CB flat panel detector. An anthropomorphic male pelvis phantom was used to acquire 500 repeated projection data at six different dose levels from 0.1 to 1.6 mAs per projection at three fixed angles. To minimize the influence of the lag effect, lag correction was performed on the consecutively acquired projection data. The noise correlation coefficient between detector bin pairs was calculated from the corrected projection data. The noise correlation among CBCT projection data was then incorporated into the covariance matrix of the penalized weighted least-squares (PWLS) criterion for noise reduction of low-dose CBCT. Results: The analyses of the repeated measurements show that noise correlation coefficients are nonzero between the nearest neighboring bins of CBCT projection data. The average noise correlation coefficients for the first- and second-order neighbors are 0.20 and 0.06, respectively. The noise correlation coefficients are independent of the dose level. Reconstruction of the pelvis phantom shows that the PWLS criterion with consideration of noise correlation (PWLS-Cor) results in a lower noise level as compared to the PWLS criterion without considering the noise correlation (PWLS-Dia) at the matched resolution. At the 2.0 mm resolution level in the axial-plane noise resolution tradeoff analysis, the noise level of the PWLS-Cor reconstruction is 6.3% lower than that of the PWLS-Dia reconstruction. Conclusions: Noise is correlated among nearest neighboring

  19. Low-dose budesonide for maintenance of clinical remission in collagenous colitis: a randomised, placebo-controlled, 12-month trial

    PubMed Central

    Münch, Andreas; Bohr, Johan; Miehlke, Stephan; Benoni, Cecilia; Olesen, Martin; Öst, Åke; Strandberg, Lars; Hellström, Per M; Hertervig, Erik; Armerding, Peter; Stehlik, Jiri; Lindberg, Greger; Björk, Jan; Lapidus, Annika; Löfberg, Robert; Bonderup, Ole; Avnström, Sören; Rössle, Martin; Dilger, Karin; Mueller, Ralph; Greinwald, Roland; Tysk, Curt; Ström, Magnus

    2016-01-01

    Objective This 1-year study aimed to assess low-dose budesonide therapy for maintenance of clinical remission in patients with collagenous colitis. Design A prospective, randomised, placebo-controlled study beginning with an 8-week open-label induction phase in which patients with histologically confirmed active collagenous colitis received budesonide (Budenofalk, 9 mg/day initially, tapered to 4.5 mg/day), after which 92 patients in clinical remission were randomised to budesonide (mean dose 4.5 mg/day; Budenofalk 3 mg capsules, two or one capsule on alternate days) or placebo in a 12-month double-blind phase with 6 months treatment-free follow-up. Primary endpoint was clinical remission throughout the double-blind phase. Results Clinical remission during open-label treatment was achieved by 84.5% (93/110 patients). The median time to remission was 10.5 days (95% CI (9.0 to 14.0 days)). The maintenance of clinical remission at 1 year was achieved by 61.4% (27/44 patients) in the budesonide group versus 16.7% (8/48 patients) receiving placebo (treatment difference 44.5% in favour of budesonide; 95% CI (26.9% to 62.7%), p<0.001). Health-related quality of life was maintained during the 12-month double-blind phase in budesonide-treated patients. During treatment-free follow-up, 82.1% (23/28 patients) formerly receiving budesonide relapsed after study drug discontinuation. Low-dose budesonide over 1 year resulted in few suspected adverse drug reactions (7/44 patients), all non-serious. Conclusions Budesonide at a mean dose of 4.5 mg/day maintained clinical remission for at least 1 year in the majority of patients with collagenous colitis and preserved health-related quality of life without safety concerns. Treatment extension with low-dose budesonide beyond 1 year may be beneficial given the high relapse rate after budesonide discontinuation. Trial registration numbers http://www.clinicaltrials.gov (NCT01278082) and http

  20. Low-dose performance of wafer-scale CMOS-based X-ray detectors

    NASA Astrophysics Data System (ADS)

    Maes, Willem H.; Peters, Inge M.; Smit, Chiel; Kessener, Yves; Bosiers, Jan

    2015-03-01

    Compared to published amorphous-silicon (TFT) based X-ray detectors, crystalline silicon CMOS-based active-pixel detectors exploit the benefits of low noise, high speed, on-chip integration and featuring offered by CMOS technology. This presentation focuses on the specific advantage of high image quality at very low dose levels. The measurement of very low dose performance parameters like Detective Quantum Efficiency (DQE) and Noise Equivalent Dose (NED) is a challenge by itself. Second-order effects like defect pixel behavior, temporal and quantization noise effects, dose measurement accuracy and limitation of the x-ray source settings will influence the measurements at very low dose conditions. Using an analytical model to predict the low dose behavior of a detector from parameters extracted from shot-noise limited dose levels is presented. These models can also provide input for a simulation environment for optimizing the performance of future detectors. In this paper, models for predicting NED and the DQE at very low dose are compared to measurements on different CMOS detectors. Their validity for different sensor and optical stack combinations as well as for different x-ray beam conditions was validated.

  1. Low-dose serotherapy improves early immune reconstitution after cord blood transplantation for primary immunodeficiencies.

    PubMed

    Lane, Jonathan P; Evans, Philippa T G; Nademi, Zohreh; Barge, Dawn; Jackson, Anthony; Hambleton, Sophie; Flood, Terry J; Cant, Andrew J; Abinun, Mario; Slatter, Mary A; Gennery, Andrew R

    2014-02-01

    Cord blood transplantation (CBT) is curative for many primary immunodeficiencies (PIDs) but is associated with risks of viral infection and graft-versus-host disease (GvHD). Serotherapy reduces GvHD but potentially increases the risk of viral infection by delaying immune reconstitution. Because many PID patients have pre-existing viral infections, the optimal dose of serotherapy is unclear. We performed a retrospective analysis in 34 consecutive PID patients undergoing CBT and compared immune reconstitution, viral infection, GvHD, mortality, and long-term immune function between high-dose (n = 11) and low-dose (n = 9) serotherapy. Serotherapy dose had no effect on neutrophil engraftment. Median CD3(+) engraftment occurred at 92.5 and 97 days for high- and low-dose serotherapy, respectively. The low-dose serotherapy group had higher CD3(+), CD4(+), and early thymic emigrant counts at 4 months compared with the high-dose group. GvHD severity and number of viral infections did not differ between serotherapy doses. Survival from the transplantation process was 90.9% for high-dose and 100% for low-dose groups. In conclusion, low-dose serotherapy enhanced T cell reconstitution and thymopoiesis during the first year after CBT with no increase in GvHD. PMID:24225641

  2. Management of low-dose aspirin and clopidogrel in clinical practice: a gastrointestinal perspective.

    PubMed

    Lanas, Angel; Gargallo, Carla J

    2015-06-01

    Low-dose aspirin, alone or combined with other antiplatelet agents, is increasingly prescribed for cardiovascular prevention. However, the cardiovascular benefits should be evaluated together with the gastrointestinal risks. Low-dose aspirin is associated with upper and lower gastrointestinal injury, although lower gastrointestinal effects are poorly characterized. This gastrointestinal risk differs among antiplatelets drugs users. The most important risk factors are history of peptic ulcer, older age, and concomitant use of non-steroidal anti-inflammatory drugs or dual antiplatelet therapy. Effective upper gastrointestinal prevention strategies are available and should be used in at-risk patients taking low-dose aspirin or clopidogrel. Proton pump inhibitors seem to be the best gastroprotective agents, whereas the benefits of Helicobacter pylori eradication are still unclear. Low-dose aspirin has additional effects in the gastrointestinal tract. A large body of evidence indicates that it can protect against different cancers, in particular colorectal cancer. This effect could modify the future indications for use of low-dose aspirin and the risk-benefit balance. PMID:25595209

  3. Low dose gamma irradiation enhances defined signaling components of intercellular reactive oxygen-mediated apoptosis induction

    NASA Astrophysics Data System (ADS)

    Bauer, G.

    2011-01-01

    Transformed cells are selectively removed by intercellular ROS-mediated induction of apoptosis. Signaling is based on the HOCl and the NO/peroxynitrite pathway (major pathways) and the nitryl chloride and the metal-catalyzed Haber-Weiss pathway (minor pathways). During tumor progression, resistance against intercellular induction of apoptosis is acquired through expression of membrane-associated catalase. Low dose radiation of nontransformed cells has been shown to enhance intercellular induction of apoptosis. The present study was performed to define the signaling components which are modulated by low dose gamma irradiation. Low dose radiation induced the release of peroxidase from nontransformed, transformed and tumor cells. Extracellular superoxide anion generation was strongly enhanced in the case of transformed cells and tumor cells, but not in nontransformed cells. Enhancement of peroxidase release and superoxide anion generation either increased intercellular induction of apoptosis of transformed cells, or caused a partial protection under specific signaling conditions. In tumor cells, low dose radiation enhanced the production of major signaling components, but this had no effect on apoptosis induction, due to the strong resistance mechanism of tumor cells. Our data specify the nature of low dose radiation-induced effects on specific signaling components of intercellular induction of apoptosis at defined stages of multistep carcinogenesis.

  4. What can be learned from epidemiologic studies of persons exposed to low doses of radiation?

    SciTech Connect

    Gilbert, E.S.

    1993-04-01

    The main objective of radiation risk assessment is to determine the risk of various adverse health effects associated with exposure to low doses and low dose rates. Extrapolation of risks from studies of persons exposed at high doses (generally exceeding 1 Sv) and dose rates has been the primary approach used to achieve this objective. The study of Japanese atomic bomb survivors in Hiroshima and Nagasaki has played an especially important role in risk assessment efforts. A direct assessment of the dose-response function based on studies of persons exposed at low doses and dose rates is obviously desirable. This paper focuses on the potential of both current and future nuclear workers studies for investigating the dose-response functions at low doses, and also discusses analyses making use of the low dose portion of the atomic bomb survivor data. Difficulties in using these data are the statistical imprecision of estimated dose-response parameters, and potential bias resulting from confounding factors and from uncertainties in dose estimates.

  5. Irradiation with low-dose gamma ray enhances tolerance to heat stress in Arabidopsis seedlings.

    PubMed

    Zhang, Liang; Zheng, Fengxia; Qi, Wencai; Wang, Tianqi; Ma, Lingyu; Qiu, Zongbo; Li, Jingyuan

    2016-06-01

    Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings. PMID:26945467

  6. Cytogenetics and long-term survival of patients with refractory or relapsed and refractory multiple myeloma treated with pomalidomide and low-dose dexamethasone.

    PubMed

    Dimopoulos, Meletios A; Weisel, Katja C; Song, Kevin W; Delforge, Michel; Karlin, Lionel; Goldschmidt, Hartmut; Moreau, Philippe; Banos, Anne; Oriol, Albert; Garderet, Laurent; Cavo, Michele; Ivanova, Valentina; Alegre, Adrian; Martinez-Lopez, Joaquin; Chen, Christine; Spencer, Andrew; Knop, Stefan; Bahlis, Nizar J; Renner, Christoph; Yu, Xin; Hong, Kevin; Sternas, Lars; Jacques, Christian; Zaki, Mohamed H; San Miguel, Jesus F

    2015-10-01

    Patients with refractory or relapsed and refractory multiple myeloma who no longer receive benefit from novel agents have limited treatment options and short expected survival. del(17p) and t(4;14) are correlated with shortened survival. The phase 3 MM-003 trial demonstrated significant progression-free and overall survival benefits from treatment with pomalidomide plus low-dose dexamethasone compared to high-dose dexamethasone among patients in whom bortezomib and lenalidomide treatment had failed. At an updated median follow-up of 15.4 months, the progression-free survival was 4.0 versus 1.9 months (HR, 0.50; P<0.001), and median overall survival was 13.1 versus 8.1 months (HR, 0.72; P=0.009). Pomalidomide plus low-dose dexamethasone, compared with high-dose dexamethasone, improved progression-free survival in patients with del(17p) (4.6 versus 1.1 months; HR, 0.34; P <0.001), t(4;14) (2.8 versus 1.9 months; HR, 0.49; P=0.028), and in standard-risk patients (4.2 versus 2.3 months; HR, 0.55; P<0.001). Although the majority of patients treated with high-dose dexamethasone took pomalidomide after discontinuation, the overall survival of patients treated with pomalidomide plus low-dose dexamethasone or high-dose dexamethasone was 12.6 versus 7.7 months (HR, 0.45; P=0.008) in patients with del(17p), 7.5 versus 4.9 months (HR, 1.12; P=0.761) in those with t(4;14), and 14.0 versus 9.0 months (HR, 0.85; P=0.380) in standard-risk subjects. The overall response rate was higher in patients treated with pomalidomide plus low-dose dexamethasone than in those treated with high-dose dexamethasone both among standard-risk patients (35.2% versus 9.7%) and those with del(17p) (31.8% versus 4.3%), whereas it was similar in patients with t(4;14) (15.9% versus 13.3%). The safety of pomalidomide plus low-dose dexamethasone was consistent with initial reports. In conclusion, pomalidomide plus low-dose dexamethasone is efficacious in patients with relapsed/refractory multiple myeloma

  7. Low-dose phase-based X-ray imaging techniques for in situ soft tissue engineering assessments.

    PubMed

    Izadifar, Zohreh; Honaramooz, Ali; Wiebe, Sheldon; Belev, George; Chen, Xiongbiao; Chapman, Dean

    2016-03-01

    In tissue engineering, non-invasive imaging of biomaterial scaffolds and tissues in living systems is essential to longitudinal animal studies for assessments without interrupting the repair process. Conventional X-ray imaging is inadequate for use in soft tissue engineering due to the limited absorption difference between the soft tissue and biomaterial scaffolds. X-ray phase-based imaging techniques that derive contrast from refraction or phase effects rather than absorption can provide the necessary contrast to see low-density biomaterial scaffolds and tissues in large living systems. This paper explores and compares three synchrotron phase-based X-ray imaging techniques-computed tomography (CT)-diffraction enhanced imaging (DEI), -analyzer based imaging (ABI), and -phase contrast imaging (PCI)-for visualization and characterization of low-density biomaterial scaffolds and tissues in situ for non-invasive soft tissue engineering assessments. Intact pig joints implanted with polycaprolactone scaffolds were used as the model to assess and compare the imaging techniques in terms of different qualitative and quantitative criteria. For long-term in vivo live animal imaging, different strategies for reducing the imaging radiation dose and scan time-reduced number of CT projections, region of interest, and low resolution imaging-were examined with the presented phase-based imaging techniques. The results demonstrated promising capabilities of the phase-based techniques for visualization of biomaterial scaffolds and soft tissues in situ. The low-dose imaging strategies were illustrated effective for reducing the radiation dose to levels appropriate for live animal imaging. The comparison among the imaging techniques suggested that CT-DEI has the highest efficiency in retaining image contrast at considerably low radiation doses. PMID:26761779

  8. Implementing Direct Access to Low-Dose Computed Tomography in General Practice—Method, Adaption and Outcome

    PubMed Central

    Guldbrandt, Louise Mahncke; Rasmussen, Torben Riis; Rasmussen, Finn; Vedsted, Peter

    2014-01-01

    Background Early detection of lung cancer is crucial as the prognosis depends on the disease stage. Chest radiographs has been the principal diagnostic tool for general practitioners (GPs), but implies a potential risk of false negative results, while computed tomography (CT) has a higher sensitivity. The aim of this study was to describe the implementation of direct access to low-dose CT (LDCT) from general practice. Methods We conducted a cohort study nested in a randomised study. A total of 119 general practices with 266 GPs were randomised into two groups. Intervention GPs were offered direct access to chest LDCT combined with a Continuing Medical Education (CME) meeting on lung cancer diagnosis. Results During a 19-month period, 648 patients were referred to LDCT (0.18/1000 adults on GP list/month). Half of the patients needed further diagnostic work-up, and 15 (2.3%, 95% CI: 1.3–3.8%) of the patients had lung cancer; 60% (95% CI: 32.3–83.7%) in a localised stage. The GP referral rate was 61% higher for CME participants compared to non-participants. Conclusion Of all patients referred to LDCT, 2.3% were diagnosed with lung cancer with a favourable stage distribution. Half of the referred patients needed additional diagnostic work-up. There was an association between participation in CME and use of CT scan. The proportion of cancers diagnosed through the usual fast-track evaluation was 2.2 times higher in the group of CME-participating GPs. The question remains if primary care case-finding with LDCT is a better option for patients having signs and symptoms indicating lung cancer than a screening program. Whether open access to LDCT may provide earlier diagnosis of lung cancer is yet unknown and a randomised trial is required to assess any effect on outcome. Trial Registration Clinicaltrials.gov NCT01527214 PMID:25383780

  9. Low doses of ionizing radiation to mammalian cells may rather control than cause DNA damage

    SciTech Connect

    Feinendegen, L.E.; Bond, V.P.; Sondhaus, C.A.; Altman, K.I.

    1998-12-31

    This report examines the origin of tissue effects that may follow from different cellular responses to low-dose irradiation, using published data. Two principal categories of cellular responses are considered. One response category relates to the probability of radiation-induced DNA damage. The other category consists of low-dose induced metabolic changes that induce mechanisms of DNA damage mitigation, which do not operate at high levels of exposure. Modeled in this way, tissue is treated as a complex adaptive system. The interaction of the various cellular responses results in a net tissue dose-effect relation that is likely to deviate from linearity in the low-dose region. This suggests that the LNT hypothesis should be reexamined. This paper aims at demonstrating tissue effects as an expression of cellular responses, both damaging and defensive, in relation to the energy deposited in cell mass, by use of microdosimetric concepts.

  10. Final Technical Report for the grant entitled "Genetic Factors Affecting Susceptibility to Low-Dose Radiation"

    SciTech Connect

    Morgan, William, F., Ph.D., D.Sc.

    2006-11-22

    The goal of this proposal was to test the hypothesis that mice heterozygous for the Nijmegen Breakage Syndrome (NBS1) gene are genetically susceptible to low doses of ionizing radiation. The rationale for this is that patients with NBS are radiation sensitive, because of defects in cellular responses to radiation induced genetic damage and haploinsufficiency at this genetic locus provides the potential for genetic susceptibility to low doses of ionizing radiation. Wild type and heterozygous NBS1 mice were irradiated and followed over their lifetime for radiation induced genomic instability, carcinogenesis and non-specific life shortening. No differences in cytogenetic damage, cancer induction or life span were observed between the hypomorphic mice indicating that genetic imbalance at the NBS1 loci does not modulate low dose radiation sensitivity.

  11. Alteration of cytokine profiles in mice exposed to chronic low-dose ionizing radiation

    SciTech Connect

    Shin, Suk Chul; Lee, Kyung-Mi; Kang, Yu Mi; Kim, Kwanghee; Kim, Cha Soon; Yang, Kwang Hee; Jin, Young-Woo; Kim, Chong Soon; Kim, Hee Sun

    2010-07-09

    While a high-dose of ionizing radiation is generally harmful and causes damage to living organisms, a low-dose of radiation has been shown to be beneficial in a variety of animal models. To understand the basis for the effect of low-dose radiation in vivo, we examined the cellular and immunological changes evoked in mice exposed to low-dose radiation at very low (0.7 mGy/h) and low (3.95 mGy/h) dose rate for the total dose of 0.2 and 2 Gy, respectively. Mice exposed to low-dose radiation, either at very low- or low-dose rate, demonstrated normal range of body weight and complete blood counts. Likewise, the number and percentage of peripheral lymphocyte populations, CD4{sup +} T, CD8{sup +} T, B, or NK cells, stayed unchanged following irradiation. Nonetheless, the sera from these mice exhibited elevated levels of IL-3, IL-4, leptin, MCP-1, MCP-5, MIP-1{alpha}, thrombopoietin, and VEGF along with slight reduction of IL-12p70, IL-13, IL-17, and IFN-{gamma}. This pattern of cytokine release suggests the stimulation of innate immunity facilitating myeloid differentiation and activation while suppressing pro-inflammatory responses and promoting differentiation of naive T cells into T-helper 2, not T-helper 1, types. Collectively, our data highlight the subtle changes of cytokine milieu by chronic low-dose {gamma}-radiation, which may be associated with the functional benefits observed in various experimental models.

  12. Data integration reveals key homeostatic mechanisms following low dose radiation exposure

    SciTech Connect

    Tilton, Susan C.; Matzke, Melissa M.; Sowa, Marianne B.; Stenoien, David L.; Weber, Thomas J.; Morgan, William F.; Waters, Katrina M.

    2015-05-15

    The goal of this study was to define pathways regulated by low dose radiation to understand how biological systems respond to subtle perturbations in their environment and prioritize pathways for human health assessment. Using an in vitro 3-D human full thickness skin model, we have examined the temporal response of dermal and epidermal layers to 10 cGy X-ray using transcriptomic, proteomic, phosphoproteomic and metabolomic platforms. Bioinformatics analysis of each dataset independently revealed potential signaling mechanisms affected by low dose radiation, and integrating data shed additional insight into the mechanisms regulating low dose responses in human tissue. We examined direct interactions among datasets (top down approach) and defined several hubs as significant regulators, including transcription factors (YY1, MYC and CREB1), kinases (CDK2, PLK1) and a protease (MMP2). These data indicate a shift in response across time — with an increase in DNA repair, tissue remodeling and repression of cell proliferation acutely (24–72 h). Pathway-based integration (bottom up approach) identified common molecular and pathway responses to low dose radiation, including oxidative stress, nitric oxide signaling and transcriptional regulation through the SP1 factor that would not have been identified by the individual data sets. Significant regulation of key downstream metabolites of nitrative stress was measured within these pathways. Among the features identified in our study, the regulation of MMP2 and SP1 was experimentally validated. Our results demonstrate the advantage of data integration to broadly define the pathways and networks that represent the mechanisms by which complex biological systems respond to perturbation. - Highlights: • Low dose ionizing radiation altered homeostasis in 3D skin tissue model. • Global gene/protein/metabolite data integrated using complementary statistical approaches • Time and location-specific change in matrix regulation

  13. Low Dose Radiation Hypersensitivity is Caused by p53-dependent Apoptosis

    SciTech Connect

    Enns, L; Bogen, K; Wizniak, J; Murtha, A; Weinfeld, M

    2004-04-08

    Exposure to environmental radiation and the application of new clinical modalities, such as radioimmunotherapy, have heightened the need to understand cellular responses to low dose and low-dose rate ionizing radiation. Many tumor cell lines have been observed to exhibit a hypersensitivity to radiation doses below 50 cGy, which manifests as a significant deviation from the clonogenic survival response predicted by a linear-quadratic fit to higher doses. However, the underlying processes for this phenomenon remain unclear. Using a gel microdrop/flow cytometry assay to monitor single cell proliferation at early times post irradiation, we examined the response of human A549 lung carcinoma, T98G glioma and MCF7 breast carcinoma cell lines exposed to gamma radiation doses from 0 to 200 cGy delivered at 0.18 and 22 cGy/min. The A549 and T98G cells, but not MCF7 cells, showed the marked hypersensitivity at doses <50 cGy. To further characterize the low-dose hypersensitivity, we examined the influence of low-dose radiation on cell cycle status and apoptosis by assays for active caspase-3 and phosphatidylserine translocation (annexin-V binding). We observed that caspase-3 activation and annexin-V binding mirrored the proliferation curves for the cell lines. Furthermore, the low-dose hypersensitivity and annexin-V binding to irradiated A549 and T98G cells were eliminated by treating the cells with pifithrin, an inhibitor of p53. When p53-inactive cell lines (2800T skin fibroblasts and HCT116 colorectal carcinoma cells) were examined for similar patterns, we found that there was no HRS and apoptosis was not detectable by annexin-V or caspase-3 assays. Our data therefore suggest that low-dose hypersensitivity is associated with p53-dependent apoptosis.

  14. Low-dose methotrexate inhibits methionine S-adenosyltransferase in vitro and in vivo.

    PubMed

    Wang, Yi-Cheng; Chiang, En-Pei Isabel

    2012-01-01

    Methionine S-adenosyltransferase (MAT) catalyzes the only reaction that produces the major methyl donor in mammals. Low-dose methotrexate is the most commonly used disease-modifying antirheumatic drug in human rheumatic conditions. The present study was conducted to test the hypothesis that methotrexate inhibits MAT expression and activity in vitro and in vivo. HepG2 cells were cultured under folate restriction or in low-dose methotrexate with and without folate or methionine supplementation. Male C57BL/6J mice received methotrexate regimens that reflected low-dose clinical use in humans. S-adenosylmethionine and MAT genes, proteins and enzyme activity levels were determined. We found that methionine or folate supplementation greatly improved S-adenosylmethionine in folate-depleted cells but not in cells preexposed to methotrexate. Methotrexate but not folate depletion suppressed MAT genes, proteins and activity in vitro. Low-dose methotrexate inhibited MAT1A and MAT2A genes, MATI/II/III proteins and MAT enzyme activities in mouse tissues. Concurrent folinate supplementation with methotrexate ameliorated MAT2A reduction and restored S-adenosylmethionine in HepG2 cells. However, posttreatment folinate rescue failed to restore MAT2A reduction or S-adenosylmethionine level in cells preexposed to methotrexate. Our results provide both in vitro and in vivo evidence that low-dose methotrexate inhibits MAT genes, proteins, and enzyme activity independent of folate depletion. Because polyglutamated methotrexate stays in the hepatocytes, if methotrexate inhibits MAT in the liver, then the efficacy of clinical folinate rescue with respect to maintaining hepatic S-adenosylmethionine synthesis and normalizing the methylation reactions would be limited. These findings raise concerns on perturbed methylation reactions in humans on low-dose methotrexate. Future studies on the clinical physiological consequences of MAT inhibition by methotrexate and the potential benefits of S

  15. Bleeding Risk with Long-Term Low-Dose Aspirin: A Systematic Review of Observational Studies

    PubMed Central

    García Rodríguez, Luis A.; Martín-Pérez, Mar; Hennekens, Charles H.; Rothwell, Peter M.; Lanas, Angel

    2016-01-01

    Background Low-dose aspirin has proven effectiveness in secondary and primary prevention of cardiovascular events, but is also associated with an increased risk of major bleeding events. For primary prevention, this absolute risk must be carefully weighed against the benefits of aspirin; such assessments are currently limited by a lack of data from general populations. Methods Systematic searches of Medline and Embase were conducted to identify observational studies published between 1946 and 4 March 2015 that reported the risks of gastrointestinal (GI) bleeding or intracranial hemorrhage (ICH) with long-term, low-dose aspirin (75–325 mg/day). Pooled estimates of the relative risk (RR) for bleeding events with aspirin versus non-use were calculated using random-effects models, based on reported estimates of RR (including odds ratios, hazard ratios, incidence rate ratios and standardized incidence ratios) in 39 articles. Findings The incidence of GI bleeding with low-dose aspirin was 0.48–3.64 cases per 1000 person-years, and the overall pooled estimate of the RR with low-dose aspirin was 1.4 (95% confidence interval [CI]: 1.2–1.7). For upper and lower GI bleeding, the RRs with low-dose aspirin were 2.3 (2.0–2.6) and 1.8 (1.1–3.0), respectively. Neither aspirin dose nor duration of use had consistent effects on RRs for upper GI bleeding. The estimated RR for ICH with low-dose aspirin was 1.4 (1.2–1.7) overall. Aspirin was associated with increased bleeding risks when combined with non-steroidal anti-inflammatory drugs, clopidogrel and selective serotonin reuptake inhibitors compared with monotherapy. By contrast, concomitant use of proton pump inhibitors decreased upper GI bleeding risks relative to aspirin monotherapy. Conclusions The risks of major bleeding with low-dose aspirin in real-world settings are of a similar magnitude to those reported in randomized trials. These data will help inform clinical judgements regarding the use of low-dose aspirin

  16. Optimum flash lamp annealing conditions for fabrication of low dose ion-implanted Si solar cells

    NASA Astrophysics Data System (ADS)

    Usami, A.; Nishioka, H.; Inoue, Y.

    1984-06-01

    A method to fabricate silicon solar cells was developed around low dose (nonamorphized) ion implantation and Xe flash lamp annealing under assist heating (350-550 C). Solar cells fabricated by low dose B-11/+/ (p+/n-type cell) and P-31/+/ (n+/p-type cell) implantation and flash lamp annealing showing a high efficiency of about 10.4 percent (AM2) without AR coating and BSF structures. The results were compared with those of high dose implanted cells reported previously (in this transaction). Effects of assist heating temperature were also examined.

  17. Treatment of Complex Regional Pain Syndrome (CRPS) using low dose naltrexone (LDN).

    PubMed

    Chopra, Pradeep; Cooper, Mark S

    2013-06-01

    Complex Regional Pain Syndrome (CRPS) is a neuropathic pain syndrome, which involves glial activation and central sensitization in the central nervous system. Here, we describe positive outcomes of two CRPS patients, after they were treated with low-dose naltrexone (a glial attenuator), in combination with other CRPS therapies. Prominent CRPS symptoms remitted in these two patients, including dystonic spasms and fixed dystonia (respectively), following treatment with low-dose naltrexone (LDN). LDN, which is known to antagonize the Toll-like Receptor 4 pathway and attenuate activated microglia, was utilized in these patients after conventional CRPS pharmacotherapy failed to suppress their recalcitrant CRPS symptoms. PMID:23546884

  18. Mechanisms of Low Dose Radiation-induced T helper Cell Function

    SciTech Connect

    Gridley, Daila S.

    2008-10-31

    Exposure to radiation above levels normally encountered on Earth can occur during wartime, accidents such as those at Three Mile Island and Chernobyl, and detonation of “dirty bombs” by terrorists. Relatively high levels of radiation exposure can also occur in certain occupations (low-level waste sites, nuclear power plants, nuclear medicine facilities, airline industry, and space agencies). Depression or dysfunction of the highly radiosensitive cells of the immune system can lead to serious consequences, including increased risk for infections, cancer, hypersensitivity reactions, poor wound healing, and other pathologies. The focus of this research was on the T helper (Th) subset of lymphocytes that secrete cytokines (proteins), and thus control many actions and interactions of other cell types that make up what is collectively known as the immune system. The Department of Energy (DOE) Low Dose Radiation Program is concerned with mechanisms altered by exposure to high energy photons (x- and gamma-rays), protons and electrons. This study compared, for the first time, the low-dose effects of two of these radiation forms, photons and protons, on the response of Th cells, as well as other cell types with which they communicate. The research provided insights regarding gene expression patterns and capacity to secrete potent immunostimulatory and immunosuppressive cytokines, some of which are implicated in pathophysiological processes. Furthermore, the photon versus proton comparison was important not only to healthy individuals who may be exposed, but also to patients undergoing radiotherapy, since many medical centers in the United States, as well as worldwide, are now building proton accelerators. The overall hypothesis of this study was that whole-body exposure to low-dose photons (gamma-rays) will alter CD4+ Th cell function. We further proposed that exposure to low-dose proton radiation will induce a different pattern of gene and functional changes compared to

  19. Concomitant chemoradiotherapy using low-dose weekly gemcitabine versus low-dose weekly paclitaxel in locally advanced head and neck squamous cell carcinoma: a phase III study.

    PubMed

    Halim, Amal Ahmed-Fouad; Wahba, Hanan Ahmed; El-Hadaad, Hend Ahmed; Abo-Elyazeed, Ahmed

    2012-03-01

    The objective of this study was to compare concomitant chemoradiotherapy based on weekly low-dose gemcitabine versus weekly low-dose paclitaxel in locally advanced head and neck squamous cell carcinoma. Previously, untreated patients with locally advanced squamous cell carcinoma of the head and neck were randomly assigned to one of the two concomitant chemoradiation regimens: (1) weekly gemcitabine at a dose of 100 mg/m(2) over 30 min 1-2 h before radiotherapy and (2) weekly paclitaxal at a dose of 20 mg/m(2) over 60 min 4-6 h before radiotherapy. The planned radiotherapy dose was 65 Gy over 6.5 weeks in 32 settings. Two hundred and sixteen patients were randomly divided into 2 groups: group A (110 patients) and group B (106 patients) who received concomitant weekly low-dose gemcitabine and low-dose paclitaxal, respectively, with the radiotherapy protocol. The hematological toxicity was generally mild. On the contrary, non-hematologic toxicities were severe. Grade III mucositis occurred in 36% in group A and in 24% in group B (P = 0.04). Moreover, grade III dermatitis were encountered in 24% in group A and 13% in group B (P = 0.049). Thirty-two (29%) of group A and 18(17%) of group B patients required enteral or parenteral feeding (P = 0.01). Sixteen (15%) of group A and 6 (6%) of group B required enteral or parenteral feeding that lasted for 6 months (P = 0.03). Regarding the late effect on swallowing, 8% of patients in group A and 2% of patients in group B required enteral or parenteral feeding for more than 6 months (P = 0.035). Response rates were 78 and 89% in groups A and B, respectively (P = 0.038). The 2-year progression-free survival figures were 54 and 64% of groups A and B, respectively; however, the 2-year overall survival figures were 56 and 67%, respectively. On the other hand, the 3-year progression-free survival figures were 39 and 48% for groups A and B, respectively, while the 3-year overall survival figures were 45 and 49%, respectively (P = 0

  20. Endocrine vasculatures are preferable targets of an antitumor ineffective low dose of anti-VEGF therapy.

    PubMed

    Zhang, Yin; Yang, Yunlong; Hosaka, Kayoko; Huang, Guichun; Zang, Jingwu; Chen, Fang; Zhang, Yun; Samani, Nilesh J; Cao, Yihai

    2016-04-12

    Anti-VEGF-based antiangiogenic drugs are designed to block tumor angiogenesis for treatment of cancer patients. However, anti-VEGF drugs produce off-tumor target effects on multiple tissues and organs and cause broad adverse effects. Here, we show that vasculatures in endocrine organs were more sensitive to anti-VEGF treatment than tumor vasculatures. In thyroid, adrenal glands, and pancreatic islets, systemic treatment with low doses of an anti-VEGF neutralizing antibody caused marked vascular regression, whereas tumor vessels remained unaffected. Additionally, a low dose of VEGF blockade significantly inhibited the formation of thyroid vascular fenestrae, leaving tumor vascular structures unchanged. Along with vascular structural changes, the low dose of VEGF blockade inhibited vascular perfusion and permeability in thyroid, but not in tumors. Prolonged treatment with the low-dose VEGF blockade caused hypertension and significantly decreased circulating levels of thyroid hormone free-T3 and -T4, leading to functional impairment of thyroid. These findings show that the fenestrated microvasculatures in endocrine organs are more sensitive than tumor vasculatures in response to systemic anti-VEGF drugs. Thus, our data support the notion that clinically nonbeneficial treatments with anti-VEGF drugs could potentially cause adverse effects. PMID:27035988

  1. Efficacy of a Low Dose of Estrogen on Antioxidant Defenses and Heart Rate Variability

    PubMed Central

    Casali, Karina Rabello; Baraldi, Dhãniel; Conzatti, Adriana; Araújo, Alex Sander da Rosa; Khaper, Neelam; Llesuy, Susana; Rigatto, Katya; Belló-Klein, Adriane

    2014-01-01

    This study tested whether a low dose (40% less than the pharmacological dose of 17-β estradiol) would be as effective as the pharmacological dose to improve cardiovascular parameters and decrease cardiac oxidative stress. Female Wistar rats (n = 9/group) were divided in three groups: (1) ovariectomized (Ovx), (2) ovariectomized animals treated for 21 days with low dose (LE; 0.2 mg), and (3) high dose (HE; 0.5 mg) 17-β estradiol subcutaneously. Hemodynamic assessment and spectral analysis for evaluation of autonomic nervous system regulation were performed. Myocardial superoxide dismutase (SOD) and catalase (CAT) activities, redox ratio (GSH/GSSG), total radical-trapping antioxidant potential (TRAP), hydrogen peroxide, and superoxide anion concentrations were measured. HE and LE groups exhibited an improvement in hemodynamic function and heart rate variability. These changes were associated with an increase in the TRAP, GSH/GSSG, SOD, and CAT. A decrease in hydrogen peroxide and superoxide anion was also observed in the treated estrogen groups as compared to the Ovx group. Our results indicate that a low dose of estrogen is just as effective as a high dose into promoting cardiovascular function and reducing oxidative stress, thereby supporting the approach of using low dose of estrogen in clinical settings to minimize the risks associated with estrogen therapy. PMID:24738017

  2. Mammalian Tissue Response to Low Dose Ionizing Radiation: The Role of Oxidative Metabolism and Intercellular Communication

    SciTech Connect

    Azzam, Edouard I

    2013-01-16

    The objective of the project was to elucidate the mechanisms underlying the biological effects of low dose/low dose rate ionizing radiation in organs/tissues of irradiated mice that differ in their susceptibility to ionizing radiation, and in human cells grown under conditions that mimic the natural in vivo environment. The focus was on the effects of sparsely ionizing cesium-137 gamma rays and the role of oxidative metabolism and intercellular communication in these effects. Four Specific Aims were proposed. The integrated outcome of the experiments performed to investigate these aims has been significant towards developing a scientific basis to more accurately estimate human health risks from exposures to low doses ionizing radiation. By understanding the biochemical and molecular changes induced by low dose radiation, several novel markers associated with mitochondrial functions were identified, which has opened new avenues to investigate metabolic processes that may be affected by such exposure. In particular, a sensitive biomarker that is differentially modulated by low and high dose gamma rays was discovered.

  3. CANCER RISKS ATTRIBUTABLE TO LOW DOSES OF IONIZING RADIATION - ASSESSING WHAT WE REALLY KNOW?

    EPA Science Inventory

    Cancer Risks Attributable to Low Doses of Ionizing Radiation - What Do We Really Know?

    Abstract
    High doses of ionizing radiation clearly produce deleterious consequences in humans including, but not exclusively, cancer induction. At very low radiation doses the situatio...

  4. MECHANISMS OF ENHANCED CELL KILLING AT LOW DOSES: IMPLICATIONS FOR RADIATION RISK

    EPA Science Inventory

    We have determined previously that radiation sensitivity can be dose-dependent so that small acute exposures (and possibly exposures at very low dose rates) are more lethal per unit dose than larger exposures above a threshold (typically 5-40 cGy) where radioresistance increases....

  5. ANNUAL PROGRESS REPORT. LOW-DOSE RISK, DECISIONS, AND RISK COMMUNICATION

    EPA Science Inventory

    This report summarizes work after 20 month of a 36-month project. To conduct basic research on how people receive, evaluate, and form positions on scientific information and its relationship to low-dose radiation exposure. There are three major areas of study in our research prog...

  6. Analysis of bipolar linear circuit response mechanisms for high and low dose rate total dose irradiations

    SciTech Connect

    Barnaby, H.; Tausch, H.J.; Turfler, R.; Cole, P.; Baker, P.; Pease, R.L.

    1996-12-01

    A methodology is presented for the identification of circuit total dose response mechanisms in bipolar linear microcircuits irradiated at high and low dose rates. This methodology includes manual circuit analysis, circuit simulations with SPICE using extracted device parameters, and selective irradiations of portions of the circuit using a scanning electron microscope.

  7. [The issue of low doses in radiation therapy and impact on radiation-induced secondary malignancies].

    PubMed

    Chargari, Cyrus; Cosset, Jean-Marc

    2013-12-01

    Several studies have well documented that the risk of secondary neoplasms is increasing among patients having received radiation therapy as part of their primary anticancer treatment. Most frequently, radiation-induced neoplasms occur in volume exposed to high doses. However, the impact of "low" doses (<5 Gy) in radiation-induced carcinogenesis should be clinically considered because modern techniques of intensity-modulated radiation therapy (IMRT) or stereotactic irradiation significantly increase tissue volumes receiving low doses. The risk inherent to these technologies remains uncertain and estimates closely depend on the chosen risk model. According to the (debated) linear no-threshold model, the risk of secondary neoplasms could be twice higher with IMRT, as compared to conformal radiation therapy. It seems that only proton therapy could decrease both high and low doses delivered to non-target volumes. Except for pediatric tumors, for which the unequivocal risk of second malignancies (much higher than in adults) should be taken into account, epidemiological data suggest that the risk of secondary cancer related to low doses could be very low, even negligible in some cases. However, clinical follow-up remains insufficient and a marginal increase in secondary tumors could counterbalance the benefit of a highly sophisticated irradiation technique. It therefore remains necessary to integrate the potential risk of new irradiation modalities in a risk-adapted strategy taking into account therapeutic objectives but also associated risk factors, such as age (essentially), chemotherapy, or life style. PMID:24257106

  8. Effects of Low-Dose Mindfulness-Based Stress Reduction (MBSR-ld) on Working Adults

    ERIC Educational Resources Information Center

    Klatt, Maryanna D.; Buckworth, Janet; Malarkey, William B.

    2009-01-01

    Mindfulness-based stress reduction (MBSR) has produced behavioral, psychological, and physiological benefits, but these programs typically require a substantial time commitment from the participants. This study assessed the effects of a shortened (low-dose [ld]) work-site MBSR intervention (MBSR-ld) on indicators of stress in healthy working…

  9. Low dose titration of copper oxide wire particles for control of gastrointestinal nematodes in weaned kids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to determine whether a low dose of copper oxide wire particles (COWP) would be as effective as a higher dose in reducing gastrointestinal nematodes (GIN) infection. In May 2006, 40 Boer x Spanish doe and wether kids naturally infected with GIN were weaned (97 ± 2 days of age) and ...

  10. Rewarding effects of ethanol combined with low doses of morphine through dopamine D1 receptors.

    PubMed

    Ise, Yuya; Mori, Tomohisa; Katayama, Shirou; Nagase, Hiroshi; Suzuki, Tsutomu

    2013-01-01

    This study investigated whether ethanol combined with low doses of morphine produces rewarding effects in rats. Ethanol (0.075-1.2 g/kg, intraperitoneal [i.p.]) alone did not induce place preference. A moderate dose (1 mg/kg, s.c.), but not a low dose (0.1 mg/kg), of morphine induced a significant place preference. The combination of ethanol (0.075-0.6 g/kg, i.p.) and 0.1 mg/kg of morphine, as well as low doses of morphine (0.03-0.1 mg/kg, subcutaneous [s.c.]) combined with ethanol (0.3 g/kg, i.p.), induced a significant place preference. The combined effect of ethanol and morphine was significantly attenuated by naloxone (0.3 mg/kg, s.c.), naltrindole (1.0 mg/kg, s.c.), or long-term administration of the dopamine D1 receptor antagonist SCH23390 (1.0 mg/kg/day, s.c.). These results suggest that the rewarding effect induced by ethanol and a low dose of morphine is mediated by activation of the central opioidergic and dopaminergic systems through dopamine D1 receptors. PMID:23470804

  11. Effect of Low-Dose MDCT and Iterative Reconstruction on Trabecular Bone Microstructure Assessment.

    PubMed

    Kopp, Felix K; Holzapfel, Konstantin; Baum, Thomas; Nasirudin, Radin A; Mei, Kai; Garcia, Eduardo G; Burgkart, Rainer; Rummeny, Ernst J; Kirschke, Jan S; Noël, Peter B

    2016-01-01

    We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods. PMID:27447827

  12. Low-Dose Palliative Radiotherapy for Cutaneous B- and T-Cell Lymphomas

    SciTech Connect

    Neelis, Karen J. Schimmel, Erik C.; Vermeer, Maarten H.; Senff, Nancy J.; Willemze, Rein; Noordijk, Evert M.

    2009-05-01

    Purpose: To determine the efficacy of low-dose palliative radiotherapy for both low-grade malignant cutaneous B-cell lymphomas (CBCLs) and cutaneous T-cell lymphomas (mycosis fungoides). Methods and Materials: A total of 18 patients with low-grade CBCL (10 primary cutaneous marginal zone B-cell and 8 primary cutaneous follicle center lymphomas) with 44 symptomatic plaques and tumors underwent low-dose (4 Gy in two fractions) local radiotherapy. A total of 31 patients with mycosis fungoides were treated at 82 symptomatic sites, initially with 4 Gy and later with 8 Gy in two fractions. Results: The complete response rate for CBCL lesions was 72%. Of the 44 B-cell lymphoma lesions, 13 were re-treated to the same site after a median of 6.3 months because of persistent (n = 8) or recurrent (n = 5) symptomatic disease. Of the mycosis fungoides patients treated with 4 Gy in two fractions (17 lesions), 70% failed to respond. Increasing the dose to 8 Gy in two fractions yielded a complete response rate of 92% (60 of 65 lesions). The patients in whom low-dose radiotherapy failed were retreated with 20 Gy in eight fractions. Conclusion: Our results have demonstrated that low-dose involved-field radiotherapy induces a high response rate in both CBCL and cutaneous T-cell lymphoma lesions without any toxicity. Therefore, this treatment is now our standard palliative treatment. At progression, it is safe and feasible to apply greater radiation doses.

  13. DETECTION OF LOW DOSE RADIATION INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENNTIAL FLUORESENCE ASSAY

    EPA Science Inventory

    A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposures...

  14. DETECTION OF LOW DOSE RADIATION INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENTIAL FLUORESCENCE ASSAY

    EPA Science Inventory

    A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposur...

  15. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells

    NASA Astrophysics Data System (ADS)

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-01

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation.

  16. Effects of Chronic Low-Dose Radiation on Human Neural Progenitor Cells

    PubMed Central

    Katsura, Mari; Cyou-Nakamine, Hiromasa; Zen, Qin; Zen, Yang; Nansai, Hiroko; Amagasa, Shota; Kanki, Yasuharu; Inoue, Tsuyoshi; Kaneki, Kiyomi; Taguchi, Akashi; Kobayashi, Mika; Kaji, Toshiyuki; Kodama, Tatsuhiko; Miyagawa, Kiyoshi; Wada, Youichiro; Akimitsu, Nobuyoshi; Sone, Hideko

    2016-01-01

    The effects of chronic low-dose radiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-dose radiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiation dose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-dose radiation. PMID:26795421

  17. Antinociceptive effects of low dose lumbosacral epidural ropivacaine in healthy ponies.

    PubMed

    van Loon, Johannes P A M; Menke, Eveline S; Doornenbal, Arie; Back, Willem; Hellebrekers, Ludo J

    2012-07-01

    The objective of this study was to evaluate the safety and efficacy of low dose lumbosacral epidural ropivacaine in ponies. Antinociceptive effects of epidural ropivacaine were evaluated by means of mechanical nociceptive thresholds (MNTs) at several spinal levels in conscious ponies. The effects of ropivacaine on nociceptive afferent transmission to the spinal cord were also assessed by measuring spinal cord somatosensory evoked potentials (SSEPs) in anaesthetised ponies. Ataxia scores were determined in conscious ponies to assess the effects on motor function. A randomised, placebo controlled, double blind cross-over design was used. Low dose lumbosacral epidural ropivacaine led to increases in MNTs at various anatomical locations with a maximum effect at the lumbosacral and sacrococcygeal regions, both with respect to increase in threshold and duration of effect. Analysis of SSEPs showed that epidural ropivacaine influenced both Aβ- and Aδ-mediated afferent transmission to the spinal cord at the level of the lumbosacral junction. Ponies showed mild ataxia after low dose lumbosacral epidural ropivacaine, but all ponies remained standing. Application of low dose lumbosacral epidural ropivacaine provided safe and efficacious antinociceptive effects in conscious and anaesthetised ponies, and could therefore be a valuable addition to multimodal analgesic protocols in Equidae. PMID:22398129

  18. Effect of Low-Dose MDCT and Iterative Reconstruction on Trabecular Bone Microstructure Assessment

    PubMed Central

    Baum, Thomas; Nasirudin, Radin A.; Mei, Kai; Garcia, Eduardo G.; Burgkart, Rainer; Rummeny, Ernst J.; Kirschke, Jan S.; Noël, Peter B.

    2016-01-01

    We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods. PMID:27447827

  19. Low Doses of Camptothecin Induced Hormetic and Neuroprotective Effects in PC12 Cells

    PubMed Central

    Zhang, Chao; Chen, Shenghui; Bao, Jiaolin; Zhang, Yulin; Huang, Borong; Jia, Xuejing; Chen, Meiwan; Wan, Jian-Bo; Su, Huanxing; Wang, Yitao

    2015-01-01

    Hormetic response is an adaptive mechanism for a cell or organism surviving in an unfavorable environment. It has been an intriguing subject of researches covering a broad range of biological and medical disciplines, in which the underlying significance and molecular mechanisms are under intensive investigation. In the present study, we demonstrated that topoisomerase I inhibitor camptothecin (CPT), a potent anticancer agent, induced an obvious hormetic response in rat pheochromocytoma PC12 cells. Camptothecin inhibited PC12 cell growth at relative high doses as generally acknowledged while stimulated the cell growth by as much as 39% at low doses. Moreover, low doses of CPT protected the cells from hydrogen peroxide (H2O2)-induced cell death. Phosphoinositide 3-kinase (PI3K)/Akt and nuclear factor-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathways were reported playing pivotal roles in protecting cells from oxidative stress. We observed that these 2 pathways were upregulated by low doses of CPT, as evidenced by increased levels of phosphorylated PI3K, phosphorylated Akt, phosphorylated mammalian target of rapamycin, Nrf2, and HO-1; and abolishment of the growth-promoting and neuroprotective effects of CPT by LY294002, a PI3K inhibitor. These results suggest that the hormetic and neuroprotective effects of CPT at low doses on PC12 cells were attributable, at least partially, to upregulated PI3K/Akt and Nrf2/HO-1 pathways. PMID:26674066

  20. Experimental characterization of the low-dose envelope of spot scanning proton beams

    NASA Astrophysics Data System (ADS)

    Sawakuchi, Gabriel O.; Zhu, X. Ronald; Poenisch, Falk; Suzuki, Kazumichi; Ciangaru, George; Titt, Uwe; Anand, Aman; Mohan, Radhe; Gillin, Michael T.; Sahoo, Narayan

    2010-06-01

    In scanned proton beam radiotherapy, multiple pencil beams are used to deliver the total dose to the target volume. Because the number of such beams can be very large, an accurate dosimetric characterization of every single pencil beam is important to provide adequate input data for the configuration of the treatment planning system. In this work, we present a method to measure the low-dose envelope of single pencil beams, known to play a meaningful role in the dose computation for scanned proton beams. We measured the low-dose proton beam envelope, which extends several centimeters outwards from the center of each single pencil beam, by acquiring lateral dose profile data, down to relative dose levels that were a factor of 104 lower than the central axis dose. The overall effect of the low-dose envelope on the total dose delivered by multiple pencil beams was determined by measuring the dose output as a function of field size. We determined that the low-dose envelope can be influential even for fields as large as 20 cm × 20 cm.

  1. Local low dose streptokinase in the treatment of acute peripheral arterial occlusion.

    PubMed

    Breslau, P J; Van der Linden, C J; Janevski, B; Jörning, P J

    1984-06-01

    Case report of local low dose streptokinase therapy in a patient with acute occlusion of the left branch of an aortobifurcation graft. Objective evidence of complete thrombolysis was demonstrated both by arteriography and hemodynamic parameters. In carefully selected cases this thrombolytic therapy is a promising alternative to surgery. PMID:6738887

  2. Safety and efficacy of low-dose, subacute exposure of mature ewes to sodium chlorate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to determine the safety and efficacy of low-dose, subacute exposure of mature ewes to NaClO3 in the drinking water. Twenty-five ewes (BW = 62.5 ± 7.3 kg) were placed indoors in individual pens with ad libitum access to water and feed. After 7 d of adaptation, ewes were assigned ran...

  3. Benefits and risks of low-dose glucocorticoid treatment in the patient with rheumatoid arthritis

    PubMed Central

    Wells, Alvin F.

    2014-01-01

    Glucocorticosteroids (GCs) have been employed extensively for the treatment of rheumatoid arthritis (RA) and other autoimmune and systemic inflammatory disorders. Their use is supported by extensive literature and their utility is reflected in their incorporation into current treatment guidelines for RA and other conditions. Nevertheless, there is still some concern regarding the long-term use of GCs because of their potential for clinically important adverse events, particularly with an extended duration of treatment and the use of high doses. This article systematically reviews the efficacy for radiological and clinical outcomes for low-dose GCs (defined as ≤10 mg/day prednisone equivalent) in the treatment of RA. Results reviewed indicated that low-dose GCs, usually administered in combination with synthetic DMARDs, most often MTX, significantly improve structural outcomes and decrease symptom severity in patients with RA. Safety data indicate that GC-associated adverse events are dose related, but still occur in patients receiving low doses of these agents. Concerns about side effects associated with GCs have prompted the development of new strategies aimed at improving safety without compromising efficacy. These include altering the structure of existing GCs and the development of delayed-release GC formulations so that drug delivery is timed to match greatest symptom severity. Optimal use of low-dose GCs has the potential to improve long-term outcomes for patients with RA. PMID:24729402

  4. BYSTANDERS, ADAPTIVE RESPONSES AND GENOMIC INSTABILITY - POTENTIAL MODIFIERS OF LOW-DOSE CANCER RESPONSES.

    EPA Science Inventory

    Bystanders, Adaptive Responses and Genomic Instability -Potential Modifiers ofLow-Dose
    Cancer Responses
    .
    There has been a concerted effort in the field of radiation biology to better understand cellular
    responses that could have an impact on the estin1ation of cancer...

  5. The prevalence of intolerance for low-dose acetylsalicylacid in the secondary prevention of atherothrombosis.

    PubMed

    Tournoij, E; Peters, R J G; Langenberg, M; Kanhai, K J K; Moll, F L

    2009-05-01

    Daily low-dose acetylsalicylacid (ASA) is prescribed to patients with atherothrombosis frequently to prevent vascular complications. In reports on complications and side effects of low-dose ASA use in the literature there is a range of definitions. We explored the incidence, characteristics and consequences of symptoms suggestive of ASA intolerance in patients on low-dose ASA. General practitioners and specialists in 105 centres were asked to review their patient files for the last 10 consecutive patients who were prescribed ASA. Participating patients completed a questionnaire about their current ASA use (doctors completed the questionnaire together with the patients), use of co-medication and symptoms suggestive of ASA intolerance. A total of 947 patients were included in this study. Sixty patients (6.6%) had ceased ASA treatment, predominantly because of the occurrence of side effects suspected to be caused by ASA use. A quarter of the patients concomitantly used an anti-acid agent. Of the 947 patients, 271 (30.6%) indicated symptoms during ASA intake. The most common symptoms were related to the gastrointestinal tract (25.1%). In patients prescribed a low-dose of ASA monotherapy, side effects suggestive of intolerance are common. More awareness should be created to detect and treat these symptoms, because the occurrence of side effects is the most important reason for patients to discontinue ASA treatment. PMID:19297216

  6. Lack of nontargeted effects in murine bone marrow after low-dose in vivo X irradiation.

    PubMed

    Zyuzikov, Nikolay A; Coates, Philip J; Parry, John M; Lorimore, Sally A; Wright, Eric G

    2011-03-01

    Exposure to high doses of ionizing radiation unequivocally produces adverse health effects including malignancy. At low doses the situation is much less clear, because effects are generally too small to be estimated directly by epidemiology, and extrapolation of risk and establishment of international rules and standards rely on the linear no-threshold (LNT) concept. Claims that low doses are more damaging than would be expected from LNT have been made on the basis of in vitro studies of nontargeted bystander effects and genomic instability, but relevant investigations of primary cells and tissues are limited. Here we show that after low-dose low-LET in vivo radiation exposures in the 0-100-mGy range of murine bone marrow there is no evidence of a bystander effect, assessed by p53 pathway signaling, nor is there any evidence for longer-term chromosomal instability in the bone marrow at doses below 1000 mGy. The data are not consistent with speculations based on in vitro nontargeted effects that low-dose X radiation is more damaging than would be expected from linear extrapolation. PMID:21388275

  7. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors.

    PubMed

    Sasaki, Masao S; Tachibana, Akira; Takeda, Shunichi

    2014-05-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to (239)Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation-environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. PMID:24366315

  8. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors

    PubMed Central

    Sasaki, Masao S.; Tachibana, Akira; Takeda, Shunichi

    2014-01-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the ‘integrate-and-fire’ algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to 239Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation–environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. PMID:24366315

  9. Chronic Low Dose Chlorine Exposure Aggravates Allergic Inflammation and Airway Hyperresponsiveness and Activates Inflammasome Pathway

    PubMed Central

    Kim, Sae-Hoon; Park, Da-Eun; Lee, Hyun-Seung; Kang, Hye-Ryun; Cho, Sang-Heon

    2014-01-01

    Background Epidemiologic clinical studies suggested that chronic exposure to chlorine products is associated with development of asthma and aggravation of asthmatic symptoms. However, its underlying mechanism was not clearly understood. Studies were undertaken to define the effects and mechanisms of chronic low-dose chlorine exposure in the pathogenesis of airway inflammation and airway hyperresponsiveness (AHR). Methods Six week-old female BALB/c mice were sensitized and challenged with OVA in the presence and absence of chronic low dose chlorine exposure of naturally vaporized gas of 5% sodium hypochlorite solution. Airway inflammation and AHR were evaluated by bronchoalveolar lavage (BAL) cell recovery and non-invasive phlethysmography, respectively. Real-time qPCR, Western blot assay, and ELISA were used to evaluate the mRNA and protein expressions of cytokines and other inflammatory mediators. Human A549 and murine epithelial (A549 and MLE12) and macrophage (AMJ2-C11) cells were used to define the responses to low dose chlorine exposure in vitro. Results Chronic low dose chlorine exposure significantly augmented airway inflammation and AHR in OVA-sensitized and challenged mice. The expression of Th2 cytokines IL-4 and IL-5 and proinflammatory cytokine IL-1β and IL-33 were significantly increased in OVA/Cl group compared with OVA group. The chlorine exposure also activates the major molecules associated with inflammasome pathway in the macrophages with increased expression of epithelial alarmins IL-33 and TSLP in vitro. Conclusion Chronic low dose exposure of chlorine aggravates allergic Th2 inflammation and AHR potentially through activation of inflammasome danger signaling pathways. PMID:25202911

  10. Quantitative Proteomic Profiling of Low Dose Ionizing Radiation Effects in a Human Skin Model

    SciTech Connect

    Hengel, Shawna; Aldrich, Joshua T.; Waters, Katrina M.; Pasa-Tolic, Ljiljana; Stenoien, David L.

    2014-07-29

    To assess molecular responses to low doses of radiation that may be encountered during medical diagnostic procedures, nuclear accidents, or terrorist acts, a quantitative global proteomic approach was used to identify protein alterations in a reconstituted human skin tissue treated with 10 cGy of ionizing radiation. Subcellular fractionation was employed to remove highly abundant structural proteins and provide insight on radiation induced alterations in protein abundance and localization. In addition, peptides were post-fractionated using high resolution 2-dimensional liquid chromatography to increase the dynamic range of detection of protein abundance and translocation changes. Quantitative data was obtained by labeling peptides with 8-plex isobaric iTRAQ tags. A total of 207 proteins were detected with statistically significant alterations in abundance and/or subcellular localization compared to sham irradiated tissues. Bioinformatics analysis of the data indicated that the top canonical pathways affected by low dose radiation are related to cellular metabolism. Among the proteins showing alterations in abundance, localization and proteolytic processing was the skin barrier protein filaggrin which is consistent with our previous observation that ionizing radiation alters profilaggrin processing with potential effects on skin barrier functions. In addition, a large number of proteases and protease regulators were affected by low dose radiation exposure indicating that altered proteolytic activity may be a hallmark of low dose radiation exposure. While several studies have demonstrated altered transcriptional regulation occurs following low dose radiation exposures, the data presented here indicates post-transcriptional regulation of protein abundance, localization, and proteolytic processing play an important role in regulating radiation responses in complex human tissues.

  11. Low-Dose Radiation Therapy (2 Gy × 2) in the Treatment of Orbital Lymphoma

    SciTech Connect

    Fasola, Carolina E.; Jones, Jennifer C.; Huang, Derek D.; Le, Quynh-Thu; Hoppe, Richard T.; Donaldson, Sarah S.

    2013-08-01

    Purpose: Low-dose radiation has become increasingly used in the management of indolent non-Hodgkin lymphoma (NHL), but has not been studied specifically for cases of ocular adnexal involvement. The objective of this study is to investigate the effectiveness of low-dose radiation in the treatment of NHL of the ocular adnexa. Methods and Materials: We reviewed the records of 20 NHL patients with 27 sites of ocular adnexal involvement treated with low-dose radiation consisting of 2 successive fractions of 2 Gy at our institution between 2005 and 2011. The primary endpoint of this study is freedom from local relapse (FFLR). Results: At a median follow-up time of 26 months (range 7-92), the overall response rate for the 27 treated sites was 96%, with a complete response (CR) rate of 85% (n=23) and a partial response rate of 11% (n=3). Among all treated sites with CR, the 2-year FFLR was 100%, with no in-treatment field relapses. The 2-year freedom from regional relapse rate was 96% with 1 case of relapse within the ipsilateral orbit (outside of the treatment field). This patient underwent additional treatment with low-dose radiation of 4 Gy to the area of relapse achieving a CR and no evidence of disease at an additional 42 months of follow-up. Orbital radiation was well tolerated with only mild acute side effects (dry eye, conjunctivitis, transient periorbital edema) in 30% of treated sites without any reports of long-term toxicity. Conclusions: Low-dose radiation with 2 Gy × 2 is effective and well tolerated in the treatment of indolent NHL of the ocular adnexa with high response rates and durable local control with the option of reirradiation in the case of locoregional relapse.

  12. Biofilm formation of Clostridium perfringens and its exposure to low-dose antimicrobials.

    PubMed

    Charlebois, Audrey; Jacques, Mario; Archambault, Marie

    2014-01-01

    Clostridium perfringens is an opportunistic pathogen that can cause food poisoning in humans and various enterotoxemia in animal species. Very little is known on the biofilm of C. perfringens and its exposure to subminimal inhibitory concentrations of antimicrobials. This study was undertaken to address these issues. Most of the C. perfringens human and animal isolates tested in this study were able to form biofilm (230/277). Porcine clinical isolates formed significantly more biofilm than the porcine commensal isolates. A subgroup of clinical and commensal C. perfringens isolates was randomly selected for further characterization. Biofilm was found to protect C. perfringens bacterial cells from exposure to high concentrations of tested antimicrobials. Exposure to low doses of some of these antimicrobials tended to lead to a diminution of the biofilm formed. However, a few isolates showed an increase in biofilm formation when exposed to low doses of tylosin, bacitracin, virginiamycin, and monensin. Six isolates were randomly selected for biofilm analysis using scanning laser confocal microscopy. Of those, four produced more biofilm in presence of low doses of bacitracin whereas biofilms formed without bacitracin were thinner and less elevated. An increase in the area occupied by bacteria in the biofilm following exposure to low doses of bacitracin was also observed in the majority of isolates. Morphology examination revealed flat biofilms with the exception of one isolate that demonstrated a mushroom-like biofilm. Matrix composition analysis showed the presence of proteins, beta-1,4 linked polysaccharides and extracellular DNA, but no poly-beta-1,6-N-acetyl-D-glucosamine. This study brings new information on the biofilm produced by C. perfringens and its exposure to low doses of antimicrobials. PMID:24795711

  13. Proteomic-based mechanistic investigation of low-dose radiation-induced cellular responses/effects

    SciTech Connect

    Chen, Xian

    2013-10-23

    The goal of our project is to apply our unique systems investigation strategy to reveal the molecular mechanisms underlying the radiation induction and transmission of oxidative damage, adaptive response, and bystander effect at low-doses. Beginning with simple in vitro systems such as fibroblast or epithelial pure culture, our amino acid-coded mass tagging (AACT) comparative proteomic platform will be used to measure quantitatively proteomic changes at high- or low-dose level with respect to their endogenous damage levels respectively, in which a broad range of unique regulated proteins sensitive to low-dose IR will be distinguished. To zoom in how these regulated proteins interact with other in the form of networks in induction/transmission pathways, these regulated proteins will be selected as baits for making a series of fibroblast cell lines that stably express each of them. Using our newly developed method of ?dual-tagging? quantitative proteomics that integrate the capabilities of natural complex expression/formation, simple epitope affinity isolation (not through tandem affinity purification or TAP), and ?in-spectra? AACT quantitative measurements using mass spectrometry (MS), we will be able to distinguish systematically interacting proteins with each bait in real time. Further, in addition to both proteome-wide (global differentially expressed proteins) and pathway-scale (bait-specific) profiling information, we will perform a computational network analysis to elucidate a global pathway/mechanisms underlying cellular responses to real-time low-dose IR. Similarly, we will extend our scheme to investigate systematically those induction/transmission pathways occurring in a fibroblast-epithelial interacting model in which the bystander cell (fibroblast) monitor the IR damage to the target cell (epithelial cell). The results will provide the proteome base (molecular mechanisms/pathways for signaling) for the low dose radiation-induced essential tissue

  14. Biofilm formation of Clostridium perfringens and its exposure to low-dose antimicrobials

    PubMed Central

    Charlebois, Audrey; Jacques, Mario; Archambault, Marie

    2014-01-01

    Clostridium perfringens is an opportunistic pathogen that can cause food poisoning in humans and various enterotoxemia in animal species. Very little is known on the biofilm of C. perfringens and its exposure to subminimal inhibitory concentrations of antimicrobials. This study was undertaken to address these issues. Most of the C. perfringens human and animal isolates tested in this study were able to form biofilm (230/277). Porcine clinical isolates formed significantly more biofilm than the porcine commensal isolates. A subgroup of clinical and commensal C. perfringens isolates was randomly selected for further characterization. Biofilm was found to protect C. perfringens bacterial cells from exposure to high concentrations of tested antimicrobials. Exposure to low doses of some of these antimicrobials tended to lead to a diminution of the biofilm formed. However, a few isolates showed an increase in biofilm formation when exposed to low doses of tylosin, bacitracin, virginiamycin, and monensin. Six isolates were randomly selected for biofilm analysis using scanning laser confocal microscopy. Of those, four produced more biofilm in presence of low doses of bacitracin whereas biofilms formed without bacitracin were thinner and less elevated. An increase in the area occupied by bacteria in the biofilm following exposure to low doses of bacitracin was also observed in the majority of isolates. Morphology examination revealed flat biofilms with the exception of one isolate that demonstrated a mushroom-like biofilm. Matrix composition analysis showed the presence of proteins, beta-1,4 linked polysaccharides and extracellular DNA, but no poly-beta-1,6-N-acetyl-D-glucosamine. This study brings new information on the biofilm produced by C. perfringens and its exposure to low doses of antimicrobials. PMID:24795711

  15. Low Doses of Ethanol Enhance LTD-like Plasticity in Human Motor Cortex.

    PubMed

    Fuhl, Anna; Müller-Dahlhaus, Florian; Lücke, Caroline; Toennes, Stefan W; Ziemann, Ulf

    2015-12-01

    Humans liberally use ethanol for its facilitating effects on social interactions but its effects on central nervous system function remain underexplored. We have recently described that very low doses of ethanol abolish long-term potentiation (LTP)-like plasticity in human cortex, most likely through enhancement of tonic inhibition [Lücke et al, 2014, Neuropsychopharmacology 39:1508-18]. Here, we studied the effects of low-dose ethanol on long-term depression (LTD)-like plasticity. LTD-like plasticity was induced in human motor cortex by paired associative transcranial magnetic stimulation (PASLTD), and measured as decreases of motor evoked potential input-output curve (IO-curve). In addition, sedation was measured by decreases in saccade peak velocity (SPV). Ethanol in two low doses (EtOH<10mM, EtOH<20mM) was compared to single oral doses of alprazolam (APZ, 1mg) a classical benzodiazepine, and zolpidem (ZLP, 10 mg), a non-benzodiazepine hypnotic, in a double-blinded randomized placebo-controlled crossover design in ten healthy human subjects. EtOH<10mM and EtOH<20mM but not APZ or ZLP enhanced the PASLTD-induced LTD-like plasticity, while APZ and ZLP but not EtOH<10mM or EtOH<20mM decreased SPV. Non-sedating low doses of ethanol, easily reached during social drinking, enhance LTD-like plasticity in human cortex. This effect is most likely explained by the activation of extrasynaptic α4-subunit containing gamma-aminobutyric type A receptors by low-dose EtOH, resulting in increased tonic inhibition. Findings may stimulate cellular research on the role of tonic inhibition in regulating excitability and plasticity of cortical neuronal networks. PMID:26038159

  16. Adaptive-weighted total variation minimization for sparse data toward low-dose x-ray computed tomography image reconstruction.

    PubMed

    Liu, Yan; Ma, Jianhua; Fan, Yi; Liang, Zhengrong

    2012-12-01

    Previous studies have shown that by minimizing the total variation (TV) of the to-be-estimated image with some data and other constraints, piecewise-smooth x-ray computed tomography (CT) can be reconstructed from sparse-view projection data without introducing notable artifacts. However, due to the piecewise constant assumption for the image, a conventional TV minimization algorithm often suffers from over-smoothness on the edges of the resulting image. To mitigate this drawback, we present an adaptive-weighted TV (AwTV) minimization algorithm in this paper. The presented AwTV model is derived by considering the anisotropic edge property among neighboring image voxels, where the associated weights are expressed as an exponential function and can be adaptively adjusted by the local image-intensity gradient for the purpose of preserving the edge details. Inspired by the previously reported TV-POCS (projection onto convex sets) implementation, a similar AwTV-POCS implementation was developed to minimize the AwTV subject to data and other constraints for the purpose of sparse-view low-dose CT image reconstruction. To evaluate the presented AwTV-POCS algorithm, both qualitative and quantitative studies were performed by computer simulations and phantom experiments. The results show that the presented AwTV-POCS algorithm can yield images with several notable gains, in terms of noise-resolution tradeoff plots and full-width at half-maximum values, as compared to the corresponding conventional TV-POCS algorithm. PMID:23154621

  17. Low-Dose Steroid Therapy Is Associated with Decreased IL-12 Production in PBMCs of Severe Septic Patients

    PubMed Central

    Shih, Chi-Chung; Chuang, Duen-Yau; Chen, Tien-Hsing

    2016-01-01

    Background. Sepsis-induced immunosuppression may result in higher mortality rates in patients. Methods. We examined the relationship of cytokine responses from stimulated peripheral blood mononuclear cells (PBMCs) and monocyte human leukocyte antigen-DR (HLA-DR) expression (days 1 and 7) with low-dose steroid therapy in 29 septic patients. Patients were treated according to the guidelines. Thirty healthy controls were enrolled for validation. Results. Eighteen patients were prescribed low-dose steroids and 11 were not. Interleukin- (IL-) 12 responses in patients without low-dose steroid therapy on days 1 and 7 were higher than those with low-dose steroid therapy. Compared to day 1, IL-12 responses significantly increased on day 7 in patients without low-dose steroid therapy. After regression analysis, the change in the IL-12 response from day 7 to day 1 was found to be independently associated with the low-dose steroid therapy. There was no difference in monocyte HLA-DR expression between patients treated with and without low-dose steroid on day 1 or 7. No change in monocyte HLA-DR expression from day 7 to day 1 was observed in patients with or without low-dose steroid therapy. Conclusion. Decreased IL-12 response was associated with the low-dose steroid therapy in PBMCs of septic patients. PMID:27555669

  18. Low-Dose Steroid Therapy Is Associated with Decreased IL-12 Production in PBMCs of Severe Septic Patients.

    PubMed

    Wu, Huang-Pin; Shih, Chi-Chung; Chuang, Duen-Yau; Chen, Tien-Hsing

    2016-01-01

    Background. Sepsis-induced immunosuppression may result in higher mortality rates in patients. Methods. We examined the relationship of cytokine responses from stimulated peripheral blood mononuclear cells (PBMCs) and monocyte human leukocyte antigen-DR (HLA-DR) expression (days 1 and 7) with low-dose steroid therapy in 29 septic patients. Patients were treated according to the guidelines. Thirty healthy controls were enrolled for validation. Results. Eighteen patients were prescribed low-dose steroids and 11 were not. Interleukin- (IL-) 12 responses in patients without low-dose steroid therapy on days 1 and 7 were higher than those with low-dose steroid therapy. Compared to day 1, IL-12 responses significantly increased on day 7 in patients without low-dose steroid therapy. After regression analysis, the change in the IL-12 response from day 7 to day 1 was found to be independently associated with the low-dose steroid therapy. There was no difference in monocyte HLA-DR expression between patients treated with and without low-dose steroid on day 1 or 7. No change in monocyte HLA-DR expression from day 7 to day 1 was observed in patients with or without low-dose steroid therapy. Conclusion. Decreased IL-12 response was associated with the low-dose steroid therapy in PBMCs of septic patients. PMID:27555669

  19. Final Report - Epigenetics of low dose radiation effects in an animal model

    SciTech Connect

    Kovalchuk, Olga

    2014-10-22

    This project sought mechanistic understanding of the epigenetic response of tissues as well as the consequences of those responses, when induced by low dose irradiation in a well-established model system (mouse). Based on solid and extensive preliminary data we investigated the molecular epigenetic mechanisms of in vivo radiation responses, particularly – effects of low, occupationally relevant radiation exposures on the genome stability and adaptive response in mammalian tissues and organisms. We accumulated evidence that low dose irradiation altered epigenetic profiles and impacted radiation target organs of the exposed animals. The main long-term goal was to dissect the epigenetic basis of induction of the low dose radiation-induced genome instability and adaptive response and the specific fundamental roles of epigenetic changes (i.e. DNA methylation, histone modifications and miRNAs) in their generation. We hypothesized that changes in global and regional DNA methylation, global histone modifications and regulatory microRNAs played pivotal roles in the generation and maintenance low-dose radiation-induced genome instability and adaptive response. We predicted that epigenetic changes influenced the levels of genetic rearrangements (transposone reactivation). We hypothesized that epigenetic responses from low dose irradiation were dependent on exposure regimes, and would be greatest when organisms are exposed in a protracted/fractionated manner: fractionated exposures > acute exposures. We anticipated that the epigenetic responses were correlated with the gene expression levels. Our immediate objectives were: • To investigate the exact nature of the global and locus-specific DNA methylation changes in the LDR exposed cells and tissues and dissect their roles in adaptive response • To investigate the roles of histone modifications in the low dose radiation effects and adaptive response • To dissect the roles of regulatory microRNAs and their targets in low

  20. [A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position: the EOS system].

    PubMed

    Dubousset, Jean; Charpak, Georges; Dorion, Irène; Skalli, Wafa; Lavaste, François; Deguise, Jacques; Kalifa, Gabriel; Ferey, Solène

    2005-02-01

    Close collaboration between multidisciplinary specialists (physicists, biomecanical engineers, medical radiologists and pediatric orthopedic surgeons) has led to the development of a new low-dose radiation device named EOS. EOS has three main advantages: The use of a gaseous X-ray detector, invented by Georges Charpak (Nobel Prizewinner 1992), the dose necessary to obtain a 2D image of the skeletal system has been reduced by 8 to 10 times, while that required to obtain a 3D reconstruction from CT slices has fallen by a factor of 800 to 1000. The accuracy of the 3D reconstruction obtained with EOS is as good as that obtained with CT. The patient is examined in the standing (or seated) position, and is scanned simultaneously from head to feet, both frontally and laterally. This is a major advantage over conventional CT which requires the patient to be placed horizontally. -The 3D reconstructions of each element of the osteo-articular system are as precise as those obtained by conventional CT. EOS is also rapid, taking only 15 to 30 minutes to image the entire spine. PMID:16114859

  1. Low dose naltrexone administration in morphine dependent rats attenuates withdrawal-induced norepinephrine efflux in forebrain

    PubMed Central

    Van Bockstaele, Elisabeth J.; Qian, Yaping; Sterling, Robert C.; Page, Michelle E.

    2009-01-01

    The administration of low dose opioid antagonists has been explored as a potential means of detoxification in opiate dependence. Previous results from our laboratory have shown that concurrent administration of low dose naltrexone in the drinking water of rats implanted with subcutaneous morphine pellets attenuates behavioral and biochemical signs of withdrawal in brainstem noradrenergic nuclei. Noradrenergic projections originating from the nucleus tractus solitarius (NTS) and the locus coeruleus (LC) have previously been shown to be important neural substrates involved in the somatic expression of opiate withdrawal. The hypothesis that low dose naltrexone treatment attenuates noradrenergic hyperactivity typically associated with opiate withdrawal was examined in the present study by assessing norepinephrine tissue content and norepinephrine efflux using in vivo microdialysis coupled to high performance liquid chromatography (HPLC) with electrochemical detection (ED). The frontal cortex (FC), amygdala, bed nucleus of the stria terminalis (BNST) and cerebellum were analyzed for tissue content of norepinephrine following withdrawal in morphine dependent rats. Naltrexone precipitated withdrawal elicited a significant decrease in tissue content of norepinephrine in the BNST and amygdala. This decrease was significantly attenuated in the BNST of rats that received low dose naltrexone pretreatment compared to controls. No significant difference was observed in the other brain regions examined. In a separate group of rats, norepinephrine efflux was assessed with in vivo microdialysis in the BNST or the FC of morphine dependent rats or placebo treated rats subjected to naltrexone-precipitated withdrawal that received either naltrexone in their drinking water (5 mg/L) or unadulterated water. Following baseline dialysate collection, withdrawal was precipitated by injection of naltrexone and sample collection continued for an additional four hours. At the end of the

  2. Summary of the National Toxicology Program's report of the endocrine disruptors low-dose peer review.

    PubMed Central

    Melnick, Ronald; Lucier, George; Wolfe, Mary; Hall, Roxanne; Stancel, George; Prins, Gail; Gallo, Michael; Reuhl, Kenneth; Ho, Shuk-Mei; Brown, Terry; Moore, John; Leakey, Julian; Haseman, Joseph; Kohn, Michael

    2002-01-01

    At the request of the U.S. Environmental Protection Agency (U.S. EPA), the National Toxicology Program organized an independent and open peer review to evaluate the scientific evidence on low-dose effects and nonmonotonic dose-response relationships for endocrine-disrupting chemicals in mammalian species. For this peer review, "low-dose effects" referred to biologic changes that occur in the range of human exposures or at doses lower than those typically used in the standard testing paradigm of the U.S. EPA for evaluating reproductive and developmental toxicity. The demonstration that an effect is adverse was not required because in many cases the long-term health consequences of altered endocrine function during development have not been fully characterized. A unique aspect of this peer review was the willing submission of individual animal data by principal investigators of primary research groups active in this field and the independent statistical reanalyses of selected parameters prior to the peer review meeting by a subpanel of statisticians. The expert peer-review panel (the panel) also considered mechanistic data that might influence the plausibility of low-dose effects and identified study design issues or other biologic factors that might account for differences in reported outcomes among studies. The panel found that low-dose effects, as defined for this review, have been demonstrated in laboratory animals exposed to certain endocrine-active agents. In some cases where low-dose effects have been reported, the findings have not been replicated. The shape of the dose-response curves for reported effects varied with the end point and dosing regimen and were low-dose linear, threshold-appearing, or nonmonotonic. The findings of the panel indicate that the current testing paradigm used for assessments of reproductive and developmental toxicity should be revisited to see whether changes are needed regarding dose selection, animal-model selection, age when

  3. Low Dose Gamma Irradiation Potentiates Secondary Exposure to Gamma Rays or Protons in Thyroid Tissue Analogs

    SciTech Connect

    Green, Lora M

    2006-05-25

    We have utilized our unique bioreactor model to produce three-dimensional thyroid tissue analogs that we believe better represent the effects of radiation in vivo than two-dimensional cultures. Our thyroid model has been characterized at multiple levels, including: cell-cell exchanges (bystander), signal transduction, functional changes and modulation of gene expression. We have significant preliminary data on structural, functional, signal transduction and gene expression responses from acute exposures at high doses (50-1000 rads) of gamma, protons and iron (Green et al., 2001a; 2001b; 2002a; 2002b; 2005). More recently, we used our DOE funding (ending Feb 06) to characterize the pattern of radiation modulated gene expression in rat thyroid tissue analogs using low-dose/low-dose rate radiation, plus/minus acute challenge exposures. Findings from these studies show that the low-dose/low-dose rate “priming” exposures to radiation invoked changes in gene expression profiles that varied with dose and time. The thyrocytes transitioned to a “primed” state, so that when the tissue analogs were challenged with an acute exposure to radiation they had a muted response (or an increased resistance) to cytopathological changes relative to “un-primed” cells. We measured dramatic differences in the primed tissue analogs, showing that our original hypothesis was correct: that low dose gamma irradiation will potentiate the repair/adaptation response to a secondary exposure. Implications from these findings are that risk assessments based on classical in vitro tissue culture assays will overestimate risk, and that low dose rate priming results in a reduced response in gene expression to a secondary challenge exposure, which implies that a priming dose provides enhanced protection to thyroid cells grown as tissue analogs. If we can determine that the effects of radiation on our tissue analogs more closely resemble the effects of radiation in vivo, then we can better

  4. What proportions of focal liver lesions detected by unenhanced ultrasound are inconclusive?

    PubMed Central

    Willits, Iain; Burn, Julie; Cole, Helen; Hoare, Tim

    2014-01-01

    In August 2012, the National Institute for Health and Care Excellence produced positive diagnostics guidance on the ultrasound contrast agent SonoVue®, but recommended further research involving an estimation of the proportion of unenhanced ultrasound scans reporting, but not characterising, focal liver lesions, particularly in cirrhotic livers. Patient records from the Radiology Information System of an acute hospital trust were progressively filtered based on categorical fields and keywords in the free text reports, to obtain ultrasound records including the liver that were appropriate for manual analysis. In total, 21,731 records referred from general practice or out-patient clinics were analysed. Patients described as having cirrhosis were analysed as a subgroup. After automatic exclusion of records considered likely to be negative, 5812 records were manually read and categorised as focal liver lesion inconclusive, benign or malignant. In the general practice cohort of 9175 records, 746 reported the presence of one or more focal liver lesions, with 18.4% (95% CI 15.7% to 21.3%) of these records mentioning an inconclusive focal liver lesion. In the out-patient cohort of 12,556 records, 1437 reported one or more focal liver lesions, and 29.4% (95% CI 26.9% to 32.0%) of these were inconclusive. Cirrhosis was reported in 10.8% of the out-patient scans that also reported a focal liver lesion, and 47.4% (95% CI 39.3% to 55.6%) of these scans had an inconclusive focal liver lesion, compared with 27.3% (95% CI 24.9% to 29.8%) that were inconclusive in non-cirrhotic livers (odds ratio 2.4; 95% CI 1.7 to 3.4). This retrospective study indicates that unenhanced ultrasound scans, in which a focal liver lesion is detected, are frequently inconclusive, with the probability of an inconclusive scan being greater in out-patient than general practice referrals. Inconclusive focal liver lesions were also reported in greater proportions of cirrhotic than non-cirrhotic livers. The

  5. Adverse Drug Effects and Preoperative Medication Factors Related to Perioperative Low-Dose Ketamine Infusions.

    PubMed

    Schwenk, Eric S; Goldberg, Stephen F; Patel, Ronak D; Zhou, Jon; Adams, Douglas R; Baratta, Jaime L; Viscusi, Eugene R; Epstein, Richard H

    2016-01-01

    High-dose opioid administration is associated with significant adverse events. Evidence suggests that low-dose ketamine infusions improve perioperative analgesia over conventional opioid management, but usage is highly variable. Ketamine's adverse drug effects (ADEs) are well known, but their prevalence during low-dose infusions in a clinical setting and how often they lead to infusion discontinuation are unknown. The purposes of this study were 3-fold: (1) to identify patient factors associated with initiation of ketamine infusions during spine surgery, (2) to identify specific spine procedures in which ketamine has been used most frequently, and (3) to identify ADEs associated with postoperative ketamine infusions and which ADEs most frequently led to discontinuation. Spine surgery was chosen because of its association with moderate to severe pain and a relatively high use of ketamine infusions in this population at our hospital. PMID:27281730

  6. Low-dose Amisulpride for Debilitating Clozapine-induced Sialorrhea: Case Series and Review of Literature.

    PubMed

    Kulkarni, Ranganath R

    2015-01-01

    Clozapine-induced sialorrhea (CIS) affects about one-third of patients treated with clozapine, at times can be stigmatizing, socially embarrassing, disabling, affect quality-of-life, cause poor compliance and can be potentially life-threatening adverse effect. Prompt and effective treatment of CIS may assist treatment tolerability, adherence, and better outcomes in patients with treatment nonresponsive schizophrenia. The beneficial effect of amisulpride augmentation of clozapine therapy for such patients may be enhanced by its anti-salivatory effect on CIS. Current series of five subjects who developed CIS that responded poorly to anticholinergic drugs found drastic improvement in daytime and nocturnal CIS with very low-dose (50-100 mg/day) of amisulpride. Low-dose amisulpride augmentation may also provide strong ameliorating effect on CIS. Nevertheless, a long-term, large-scale study with a broader dose range is warranted to evaluate the stability of this effect across time. PMID:26702180

  7. Low-dose Amisulpride for Debilitating Clozapine-induced Sialorrhea: Case Series and Review of Literature

    PubMed Central

    Kulkarni, Ranganath R.

    2015-01-01

    Clozapine-induced sialorrhea (CIS) affects about one-third of patients treated with clozapine, at times can be stigmatizing, socially embarrassing, disabling, affect quality-of-life, cause poor compliance and can be potentially life-threatening adverse effect. Prompt and effective treatment of CIS may assist treatment tolerability, adherence, and better outcomes in patients with treatment nonresponsive schizophrenia. The beneficial effect of amisulpride augmentation of clozapine therapy for such patients may be enhanced by its anti-salivatory effect on CIS. Current series of five subjects who developed CIS that responded poorly to anticholinergic drugs found drastic improvement in daytime and nocturnal CIS with very low-dose (50-100 mg/day) of amisulpride. Low-dose amisulpride augmentation may also provide strong ameliorating effect on CIS. Nevertheless, a long-term, large-scale study with a broader dose range is warranted to evaluate the stability of this effect across time. PMID:26702180

  8. Enteric coating can lead to reduced antiplatelet effect of low-dose acetylsalicylic acid.

    PubMed

    Haastrup, Peter Fentz; Grønlykke, Thor; Jarbøl, Dorte Ejg

    2015-03-01

    Low-dose acetylsalicylic acid (ASA) is widely used as antithrombotic prophylaxis. Enteric-coated ASA has been developed to decrease the risk of gastrointestinal side effects. The consequences of enteric coating on pharmacokinetics and antiplatelet effect of ASA have not systematically been assessed. This MiniReview demonstrates that data from clinical trials indicate that enteric coating can reduce the antiplatelet effect of ASA compared to plain ASA. This is possibly due to decreased bioavailability of ASA caused by prolonged solvation and absorption of the enteric-coated formulations. Therefore, low-dose enteric-coated ASA might not be bioequivalent to plain ASA, entailing the risk of insufficient cardiovascular prophylaxis. PMID:25469781

  9. Evaluation of low-dose irradiation on microbiological quality of white carrots and string beans

    NASA Astrophysics Data System (ADS)

    Koike, Amanda C. R.; Santillo, Amanda G.; Rodrigues, Flávio T.; Duarte, Renato C.; Villavicencio, Anna Lucia C. H.

    2012-08-01

    The minimally processed food provided the consumer with a product quality, safety and practicality. However, minimal processing of food does not reduce pathogenic population of microorganisms to safe levels. Ionizing radiation used in low doses is effective to maintain the quality of food, reducing the microbiological load but rather compromising the nutritional values and sensory property. The association of minimal processing with irradiation could improve the quality and safety of product. The purpose of this study was to evaluate the effectiveness of low-doses of ionizing radiation on the reduction of microorganisms in minimally processed foods. The results show that the ionizing radiation of minimally processed vegetables could decontaminate them without several changes in its properties.

  10. Low-dose ribavirin potentiates the antiviral activity of favipiravir against hemorrhagic fever viruses.

    PubMed

    Westover, Jonna B; Sefing, Eric J; Bailey, Kevin W; Van Wettere, Arnaud J; Jung, Kie-Hoon; Dagley, Ashley; Wandersee, Luci; Downs, Brittney; Smee, Donald F; Furuta, Yousuke; Bray, Mike; Gowen, Brian B

    2016-02-01

    Favipiravir is approved in Japan to treat novel or re-emerging influenza viruses, and is active against a broad spectrum of RNA viruses, including Ebola. Ribavirin is the only other licensed drug with activity against multiple RNA viruses. Recent studies show that ribavirin and favipiravir act synergistically to inhibit bunyavirus infections in cultured cells and laboratory mice, likely due to their different mechanisms of action. Convalescent immune globulin is the only approved treatment for Argentine hemorrhagic fever caused by the rodent-borne Junin arenavirus. We previously reported that favipiravir is highly effective in a number of small animal models of Argentine hemorrhagic fever. We now report that addition of low dose of ribavirin synergistically potentiates the activity of favipiravir against Junin virus infection of guinea pigs and another arenavirus, Pichinde virus infection of hamsters. This suggests that the efficacy of favipiravir against hemorrhagic fever viruses can be further enhanced through the addition of low-dose ribavirin. PMID:26711718

  11. Warfarin and low-dose aspirin for stroke prevention from severe intracranial stenosis.

    PubMed

    Bekavac, I; Hanna, J P; Sila, C A; Furland, A J

    1999-01-01

    Management of symptomatic, intracranial, large-arterial atherosclerosis is controversial. We assessed the safety and efficacy of combining warfarin and low-dose aspirin to prevent stroke from intracranial atherosclerotic stenosis failing prior treatment with either aspirin or warfarin. Patients with severe intracranial stenosis were prescribed combination therapy, warfarin (international normalized ratio [INR] 2 to 3) and aspirin 81 mg daily. Ten men and six women treated with combination therapy had one recurrent ischemic event during 382 months of therapy. No patient suffered a myocardial infarction or sudden vascular death. No serious hemorrhagic complication occurred. The combination of warfarin and low-dose aspirin seems safe and effective in preventing recurrent stroke from symptomatic, intracranial, large-arterial occlusive disease after failure with either aspirin or warfarin monotherapy. PMID:17895135

  12. [Treatment of postmenopausal osteoporosis with low doses of calcitonin and a calcitonin-anabolic combination].

    PubMed

    Szücs, J; Horváth, C; Kollin, E; Szathmári, M; Holló, I

    1992-06-01

    Menopausal osteoporotic women (age: 49-69, mean: 59.5 years) with crush fractures of the spine were treated with low doses of calcitonin (Miacalcic, 350 U/month), or with calcitonin + anabolic steroid (Retabolil, 50 mg/month). Efficacy of the therapy was controlled by single foton absorptiometry of midshaft and distal radius, by X-ray morphometry and by registering new crush fractures of the spine. Calcitonin monotherapy stopped further bone loss for two years, but at the end of the third year both absorptiometric values, as well as the radiomorphometrical index of the lumbar spine decreased significantly. In patients on calcitonin+anabolic steroid the decrease was just significant and only at radius midshaft, while at the other measured sites it was not. Two new crush fractures per 1396 patient-months occurred. Intermittent administration of low-dose calcitonin, especially together with an anabolic steroid seems to be a safe and effective therapy in established osteoporosis. PMID:1603585

  13. [Low dose vasopressin is effective for catecholamine-resistant hypotension after resection of pheochromocytoma].

    PubMed

    Kanazawa, Shinya; Uehara, Naoko; Seo, Hideya; Miyawaki, Ikuko; Yamazaki, Kazuo

    2013-10-01

    The perioperative management of pheochromocytoma is challenging for anesthesiologists and persistent hypotension secondary to cathecholamine depletion after tumor resection can be refractory to treatment. A 64-year-old man underwent right adrenalectomy for treatment of massive pheochromocytoma. Doxazosin administration was started and increased gradually to 12 mg daily. He was premedicated with doxazosin on the day of the surgery. Induction was uneventful but there was a sudden increase of blood pressure with tachycardia on handling of tumor which was controlled by intravenous remifentanil, landiolol, diltiazem, and magnesium sulfate. With dissection of the tumor, the blood pressure dropped to 65/40 mmHg, which was resistant to fluid and cathecholamine treatment. After commencement of low dose vasopressin administration (two boluses of 0.08 U followed by 1.6 U x hr(-1)), blood pressure gradually recovered to normal ranges. Low dose vasopressin can be safely used to treat postadrenalectomy hypotension and also can reduce the cathecholamine dose. PMID:24228460

  14. Clustered DNA damages induced in human hematopoietic cells by low doses of ionizing radiation

    NASA Technical Reports Server (NTRS)

    Sutherland, Betsy M.; Bennett, Paula V.; Cintron-Torres, Nela; Hada, Megumi; Trunk, John; Monteleone, Denise; Sutherland, John C.; Laval, Jacques; Stanislaus, Marisha; Gewirtz, Alan

    2002-01-01

    Ionizing radiation induces clusters of DNA damages--oxidized bases, abasic sites and strand breaks--on opposing strands within a few helical turns. Such damages have been postulated to be difficult to repair, as are double strand breaks (one type of cluster). We have shown that low doses of low and high linear energy transfer (LET) radiation induce such damage clusters in human cells. In human cells, DSB are about 30% of the total of complex damages, and the levels of DSBs and oxidized pyrimidine clusters are similar. The dose responses for cluster induction in cells can be described by a linear relationship, implying that even low doses of ionizing radiation can produce clustered damages. Studies are in progress to determine whether clusters can be produced by mechanisms other than ionizing radiation, as well as the levels of various cluster types formed by low and high LET radiation.

  15. Low-dose acetazolamide reverses periventricular white matter hyperintensities in iNPH

    PubMed Central

    Oliu, Carlos J.; Bagci, Ahmet M.; Lee, Sang H.; Kovanlikaya, Ilhami; Adams, David; Katzen, Heather; Ivkovic, Milos; Heier, Linda; Relkin, Norman

    2014-01-01

    Objective: To assess the effects of low-dose acetazolamide treatment on volumetric MRI markers and clinical outcome in idiopathic normal-pressure hydrocephalus (iNPH). Methods: We analyzed MRI and gait measures from 8 patients with iNPH with serial MRIs from an institutional review board–approved imaging protocol who had been treated off-label with low-dose acetazolamide (125–375 mg/day). MRI studies included fluid-attenuated inversion recovery and 3D T1-weighted high-resolution imaging. Automated analyses were employed to quantify each patient's ventricular, global white matter hyperintensities (WMH), and periventricular WMH (PVH) volumes prior to and throughout treatment. Clinical outcome was based on gait changes assessed quantitatively using the Boon scale. Results: Five of 8 patients responded positively to treatment, with median gait improvement of 4 points on the Boon scale. A significant decrease in PVH volume (−6.1 ± 1.9 mL, p = 0.002) was seen in these patients following treatment. One patient's gait was unchanged and 2 patients demonstrated worsened gait and were referred for shunt surgery. No reduction in PVH volume was detected in the latter 2 patients. Nonperiventricular WMH and lateral ventricle volumes remained largely unchanged in all patients. Conclusions: These preliminary findings provide new evidence that low-dose acetazolamide can reduce PVH and may improve gait in iNPH. PVH volume, reflecting transependymal CSF, is shown to be a potential MRI indicator of pharmacologic intervention effectiveness. Further studies of pharmacologic treatment of iNPH are needed and may be enhanced by incorporating quantitative MRI outcomes. Classification of evidence: This study provides Class IV evidence that low-dose acetazolamide reverses PVH volume and, in some cases, improves gait in iNPH. PMID:24634454

  16. Low-dose effects of bisphenol A on mammary gland development in rats.

    PubMed

    Mandrup, K; Boberg, J; Isling, L K; Christiansen, S; Hass, U

    2016-07-01

    Bisphenol A (BPA) is widely used in food contact materials, toys, and other products. Several studies have indicated that effects observed at doses near human exposure levels may not be observed at higher doses. Many studies have shown effects on mammary glands at low doses of BPA, however, because of small number of animals or few doses investigated these data have not been used by EFSA as point of departure for the newly assessed tolerable daily intake (TDI). We performed a study with perinatal exposure to BPA (0, 0.025, 0.25, 5, and 50 mg/kg bw/day) in rats (n = 22 mated/group). One of the aims was to perform a study robust enough to contribute to the risk assessment of BPA and to elucidate possible biphasic dose-response relationships. We investigated mammary gland effects in the offspring at 22, 100, and 400 days of age. Male offspring showed increased mammary outgrowth on pup day (PD) 22 at 0.025 mg/kg BPA, indicating an increased mammary development at this low dose only. Increased prevalence of intraductal hyperplasia was observed in BPA females exposed to 0.25 mg/kg at PD 400, but not at PD 100, and not at higher or lower doses. The present findings support data from the published literature showing that perinatal exposure to BPA can induce increased mammary growth and proliferative lesions in rodents. Our results indicate that low-dose exposure to BPA can affect mammary gland development in male and female rats, although higher doses show a different pattern of effects. The observed intraductal hyperplasia in female rats could be associated with an increased risk for developing hyperplastic lesions, which are parallels to early signs of breast neoplasia in women. Collectively, current knowledge on effects of BPA on mammary gland at low doses indicates that highly exposed humans may not be sufficiently protected. PMID:27088260

  17. Effects of Monoamine Oxidase Inhibition on the Reinforcing Properties of Low-Dose Nicotine.

    PubMed

    Smith, Tracy T; Rupprecht, Laura E; Cwalina, Samantha N; Onimus, Matthew J; Murphy, Sharon E; Donny, Eric C; Sved, Alan F

    2016-08-01

    The Food and Drug Administration (FDA) has the authority to regulate cigarette smoke constituents, and a reduction in nicotine content might benefit public health by reducing the prevalence of smoking. Research suggests that cigarette smoke constituents that inhibit monoamine oxidase (MAO) may increase the reinforcing value of low doses of nicotine. The aim of the present experiments was to further characterize the impact of MAO inhibition on the primary reinforcing and reinforcement enhancing effects of nicotine in rats. In a series of experiments, rats responded for intravenous nicotine infusions or a moderately-reinforcing visual stimulus in daily 1-h sessions. Rats received pre-session injections of known MAO inhibitors. The results show that (1) tranylcypromine (TCP), a known MAO inhibitor, increases sensitivity to the primary reinforcing effects of nicotine, shifting the dose-response curve for nicotine to the left, (2) inhibition of MAO-A, but not MAO-B, increases low-dose nicotine self-administration, (3) partial MAO-A inhibition, to the degree observed in chronic cigarette smokers, also increases low-dose nicotine self-administration, and (4) TCP decreases the threshold nicotine dose required for reinforcement enhancement. The results of the present experiments suggest cigarette smoke constituents that inhibit MAO-A, in the range seen in chronic smokers, are likely to increase the primary reinforcing and reinforcement enhancing effects of low doses of nicotine. If the FDA reduces the nicotine content of cigarettes, then variability in constituents that inhibit MAO-A could impact smoking. PMID:26955970

  18. Theoretical explanation of enhanced low dose rate sensitivity in erbium-doped optical fibers.

    PubMed

    Gilard, Olivier; Thomas, Jérémie; Troussellier, Laurent; Myara, Mikhael; Signoret, Philippe; Burov, Ekaterina; Sotom, Michel

    2012-05-01

    A new theoretical framework is proposed to explain the dose and dose-rate dependence of radiation-induced absorption in optical fibers. A first-order dispersive kinetics model is used to simulate the growth of the density of color centers during an irradiation. This model succeeds in explaining the enhanced low dose rate sensitivity observed in certain kinds of erbium-doped optical fiber and provides some insight into the physical reasons behind this sensitivity. PMID:22614396

  19. Low-dose photons modify liver response to simulated solar particle event protons.

    PubMed

    Gridley, Daila S; Coutrakon, George B; Rizvi, Asma; Bayeta, Erben J M; Luo-Owen, Xian; Makinde, Adeola Y; Baqai, Farnaz; Koss, Peter; Slater, James M; Pecaut, Michael J

    2008-03-01

    The health consequences of exposure to low-dose radiation combined with a solar particle event during space travel remain unresolved. The goal of this study was to determine whether protracted radiation exposure alters gene expression and oxidative burst capacity in the liver, an organ vital in many biological processes. C57BL/6 mice were whole-body irradiated with 2 Gy simulated solar particle event (SPE) protons over 36 h, both with and without pre-exposure to low-dose/low-dose-rate photons ((57)Co, 0.049 Gy total at 0.024 cGy/h). Livers were excised immediately after irradiation (day 0) or on day 21 thereafter for analysis of 84 oxidative stress-related genes using RT-PCR; genes up or down-regulated by more than twofold were noted. On day 0, genes with increased expression were: photons, none; simulated SPE, Id1; photons + simulated SPE, Bax, Id1, Snrp70. Down-regulated genes at this same time were: photons, Igfbp1; simulated SPE, Arnt2, Igfbp1, Il6, Lct, Mybl2, Ptx3. By day 21, a much greater effect was noted than on day 0. Exposure to photons + simulated SPE up-regulated completely different genes than those up-regulated after either photons or the simulated SPE alone (photons, Cstb; simulated SPE, Dctn2, Khsrp, Man2b1, Snrp70; photons + simulated SPE, Casp1, Col1a1, Hspcb, Il6st, Rpl28, Spnb2). There were many down-regulated genes in all irradiated groups on day 21 (photons, 13; simulated SPE, 16; photons + simulated SPE, 16), with very little overlap among groups. Oxygen radical production by liver phagocytes was significantly enhanced by photons on day 21. The results demonstrate that whole-body irradiation with low-dose-rate photons, as well as time after exposure, had a great impact on liver response to a simulated solar particle event. PMID:18302490

  20. Ventilatory effects of low-dose paraoxon result from central muscarinic effects

    SciTech Connect

    Houze, Pascal; Pronzola, Laetita; Kayouka, Maya; Villa, Antoine; Debray, Marcel; Baud, Frederic J.

    2008-12-01

    Paraoxon induces respiratory toxicity. Atropine completely reversed parathion- and paraoxon-induced respiratory toxicity. The aim of this study was to assess the peripheral or central origin of ventilatory effects of low-dose paraoxon. Male Sprague-Dawley rats were given paraoxon 0.215 mg/kg subcutaneously and treated with either atropine (10 mg/kg sc) or ascending doses of methylatropine of 5.42 (equimolar to that of atropine), 54.2, and 542 mg/kg administered subcutaneously 30 min after paraoxon. Ventilation at rest was assessed using whole-body plethysmography and rat temperature using infra-red telemetry. Results are expressed as mean {+-} SE. Statistical analysis used two-way ANOVA for repeated measurements. Paraoxon induced a significant decrease in temperature 30 min after injection lasting the 90 min of the study period. This effect was partially corrected by atropine, but not by methylatropine whatever the dose. Paraoxon induced a decrease in respiratory rate resulting from an increase in expiratory time associated with an increase in tidal volume. Atropine completely reversed the ventilatory effects of low-dose paraoxon while the equimolar dose of methylatropine had no significant effects. The 54.2 and 542 mg/kg doses of methylatropine had no significant effects. Atropine crosses the blood-brain barrier and reverses peripheral and central muscarinic effects. In contrast, methylatropine does not cross the blood-brain barrier. Atropine completely reversed the ventilatory effects of low-dose paraoxon, while methylatropine had no significant effects at doses up to 100-fold the equimolar dose of atropine. We conclude that the ventilatory effects of low-dose paraoxon are mediated by disrupted muscarinic signaling in the central nervous system.

  1. The road to linearity: why linearity at low doses became the basis for carcinogen risk assessment.

    PubMed

    Calabrese, Edward J

    2009-03-01

    This article assesses the historical foundations of how linearity at low dose became accepted by the scientific/regulatory communities. While the threshold model was used in the 1920s/1930s in establishing radiation health standards, its foundations were challenged by the genetics community who argued that radiation induced mutations in reproductive cells followed a linear response, were cumulative and deleterious. Scientific foundations of linearity for gonadal mutations were based on non-conclusive evidence as well as not being conducted at low doses. Following years of debate, leaders in the genetics community participated in the U.S. National Academy of Sciences (NAS) (1956) Biological Effects of Atomic Radiation (BEAR) BEAR I Committee, getting their perspectives accepted, incorporating linearity for radiation-induced mutational effects in risk assessment. Overtime the concept of linearity was generalized to include somatic effects induced by radiation based on a protectionist philosophy. This affected the course of radiation-induced and later chemically-induced carcinogen risk assessment. Acceptance of linearity at low dose from chemical carcinogens was strongly influenced by the NAS Safe Drinking Water Committee report of 1977 which provided the critical guidance to the U.S. EPA to adopt linear at low dose modeling for risk assessment for chemical carcinogens with little supportive data, much of which has been either discredited or seriously weakened over the past 3 decades. Nonetheless, there has been little practical change of regulatory policy concerning carcinogen risk assessment. These observations suggest that while scientific disciplines are self correcting, that regulatory 'science' fails to display the same self-correcting mechanism despite contradictory data. PMID:19247635

  2. Resource Letter EIRLD-2: Effects of Ionizing Radiation at Low Doses

    NASA Astrophysics Data System (ADS)

    Wilson, Richard

    2012-04-01

    This Resource Letter provides a guide to the literature on the effects of ionizing radiation on people at low doses. Journal articles, books and web pages are provided for the following: data at high dose levels, effects of moderate to high doses (leukemia, solid cancer, lung cancer, childhood cancer, and non-cancer outcomes), effects of dose rate, relationship to background, supra linearity and hormesis, and policy implications.

  3. Resource Letter EIRLD-1: Effects of ionizing radiation at low doses

    NASA Astrophysics Data System (ADS)

    Wilson, Richard

    1999-05-01

    This Resource Letter provides a guide to the literature on the effects of ionizing radiation on people at low doses. Journal articles, books, and web pages are provided for the following: data at high dose levels, effects of moderate to high doses (leukemia, solid cancer, lung cancer, childhood cancer and noncancer outcomes), effects of dose rate, relationship to background, supra linearity and homesis, and policy implications.

  4. The biobehavioral and neuroimmune impact of low-dose ionizing radiation

    PubMed Central

    York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

    2011-01-01

    In the clinical setting, repeated exposures (10–30) to low-doses of ionizing radiation (≤ 200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 h and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. PMID:21958477

  5. Inconsistencies and open questions regarding low-dose health effects of ionizing radiation.

    PubMed Central

    Nussbaum, R H; Köhnlein, W

    1994-01-01

    The effects on human health of exposures to ionizing radiation at low doses have long been the subject of dispute. In this paper we focus on open questions regarding the health effects of low-dose exposures that require further investigations. Seemingly contradictory findings of radiation health effects have been reported for the same exposed populations, or inconsistent estimates of radiation risks were found when different populations and exposure conditions were compared. Such discrepancies may be indicative of differences in sensitivities among the applied methods of epidemiological analysis or indicative of significant discrepancies in health consequences after comparable total exposures of different populations under varying conditions. We focus first on inconsistencies and contradictions in presentations of the state of knowledge by different authoritative experts. We then review studies that found positive associations between exposure and risks in dose ranges where traditional notions (generalized primarily from high-dose studies of A-bomb survivors or exposed animals) would have predicted negligible effects. One persistent notion in many reviews of low-dose effects is the hypothesis of reduced biological effectiveness of fractionated low-dose exposures, compared to that of the same acute dose. This assumption is not supported by data on human populations. From studies of populations that live in contaminated areas, more and more evidence is accumulating on unusual rates of various diseases other than radiation-induced malignancies, health effects that are suspected to be associated with relatively low levels of internal exposures originating from radioactive fallout. Such effects include congenital defects, neonatal mortality, stillbirths, and possibly genetically transmitted disease. A range of open questions challenges scientists to test imaginative hypotheses about induction of disease by radiation with novel research strategies. Images Figure 1. PMID

  6. Effects of Low Doses of Bisphenol A on the Metabolome of Perinatally Exposed CD-1 Mice

    PubMed Central

    Cabaton, Nicolas J.; Canlet, Cécile; Wadia, Perinaaz R.; Tremblay-Franco, Marie; Gautier, Roselyne; Molina, Jérôme; Sonnenschein, Carlos; Cravedi, Jean-Pierre; Rubin, Beverly S.; Soto, Ana M.

    2013-01-01

    Background: Bisphenol A (BPA) is a well-known endocrine disruptor used to manufacture polycarbonate plastics and epoxy resins. Exposure of pregnant rodents to low doses of BPA results in pleiotropic effects in their offspring. Objective: We used metabolomics—a method for determining metabolic changes in response to nutritional, pharmacological, or toxic stimuli—to examine metabolic shifts induced in vivo by perinatal exposure to low doses of BPA in CD-1 mice. Methods: Male offspring born to pregnant CD-1 mice that were exposed to vehicle or to 0.025, 0.25, or 25 µg BPA/kg body weight/day, from gestation day 8 through day 16 of lactation, were examined on postnatal day (PND) 2 or PND21. Aqueous extracts of newborns (PND2, whole animal) and of livers, brains, and serum samples from PND21 pups were submitted to 1H nuclear magnetic resonance spectroscopy. Data were analyzed using partial least squares discriminant analysis. Results: Examination of endogenous metabolic fingerprints revealed remarkable discrimination in whole extracts of the four PND2 newborn treatment groups, strongly suggesting changes in the global metabolism. Furthermore, statistical analyses of liver, serum, and brain samples collected on PND21 successfully discriminated among treatment groups. Variations in glucose, pyruvate, some amino acids, and neurotransmitters (γ-aminobutyric acid and glutamate) were identified. Conclusions: Low doses of BPA disrupt global metabolism, including energy metabolism and brain function, in perinatally exposed CD-1 mouse pups. Metabolomics can be used to highlight the effects of low doses of endocrine disruptors by linking perinatal exposure to changes in global metabolism. PMID:23425943

  7. Low-dose oral cadmium increases airway reactivity and lung neuronal gene expression in mice.

    PubMed

    Chandler, Joshua D; Wongtrakool, Cherry; Banton, Sophia A; Li, Shuzhao; Orr, Michael L; Barr, Dana Boyd; Neujahr, David C; Sutliff, Roy L; Go, Young-Mi; Jones, Dean P

    2016-07-01

    Inhalation of cadmium (Cd) is associated with lung diseases, but less is known concerning pulmonary effects of Cd found in the diet. Cd has a decades-long half-life in humans and significant bioaccumulation occurs with chronic dietary intake. We exposed mice to low-dose CdCl2 (10 mg/L in drinking water) for 20 weeks, which increased lung Cd to a level similar to that of nonoccupationally exposed adult humans. Cd-treated mice had increased airway hyperresponsiveness to methacholine challenge, and gene expression array showed that Cd altered the abundance of 443 mRNA transcripts in mouse lung. In contrast to higher doses, low-dose Cd did not elicit increased metallothionein transcripts in lung. To identify pathways most affected by Cd, gene set enrichment of transcripts was analyzed. Results showed that major inducible targets of low-dose Cd were neuronal receptors represented by enriched olfactory, glutamatergic, cholinergic, and serotonergic gene sets. Olfactory receptors regulate chemosensory function and airway hypersensitivity, and these gene sets were the most enriched. Targeted metabolomics analysis showed that Cd treatment also increased metabolites in pathways of glutamatergic (glutamate), serotonergic (tryptophan), cholinergic (choline), and catecholaminergic (tyrosine) receptors in the lung tissue. Protein abundance measurements showed that the glutamate receptor GRIN2A was increased in mouse lung tissue. Together, these results show that in mice, oral low-dose Cd increased lung Cd to levels comparable to humans, increased airway hyperresponsiveness and disrupted neuronal pathways regulating bronchial tone. Therefore, dietary Cd may promote or worsen airway hyperresponsiveness in multiple lung diseases including asthma. PMID:27401458

  8. Low-Dose Isotretinoin: An Option for Difficult-to-Treat Papulopustular Rosacea.

    PubMed

    van Zuuren, Esther J; Fedorowicz, Zbys

    2016-06-01

    Rosacea is a chronic disease with a profound impact on quality of life. Although there are a range of treatments for its many manifestations, some cases are difficult to treat. Sbidian et al. show in this double-blind, randomized, placebo-controlled trial that low-dose isotretinoin can be effective in treating difficult-to-treat and frequently relapsing papulopustular rosacea. PMID:27212646

  9. The biobehavioral and neuroimmune impact of low-dose ionizing radiation.

    PubMed

    York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

    2012-02-01

    In the clinical setting, repeated exposures (10-30) to low-doses of ionizing radiation (≤200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. PMID:21958477

  10. Effects of chronic low dose rotenone treatment on human microglial cells

    PubMed Central

    2009-01-01

    Background Exposure to toxins/chemicals is considered to be a significant risk factor in the pathogenesis of Parkinson's disease (PD); one putative chemical is the naturally occurring herbicide rotenone that is now used widely in establishing PD models. We, and others, have shown that chronic low dose rotenone treatment induces excessive accumulation of Reactive Oxygen Species (ROS), inclusion body formation and apoptosis in dopaminergic neurons of animal and human origin. Some studies have also suggested that microglia enhance the rotenone induced neurotoxicity. While the effects of rotenone on neurons are well established, there is little or no information available on the effect of rotenone on microglial cells, and especially cells of human origin. The aim of the present study was to investigate the effects of chronic low dose rotenone treatment on human microglial CHME-5 cells. Methods We have shown previously that rotenone induced inclusion body formation in human dopaminergic SH-SY5Y cells and therefore used these cells as a control for inclusion body formation in this study. SH-SY5Y and CHME-5 cells were treated with 5 nM rotenone for four weeks. At the end of week 4, both cell types were analysed for the presence of inclusion bodies, superoxide dismutases and cell activation (only in CHME-5 cells) using Haematoxylin and Eosin staining, immunocytochemical and western blotting methods. Levels of active caspases and ROS (both extra and intra cellular) were measured using biochemical methods. Conclusion The results suggest that chronic low dose rotenone treatment activates human microglia (cell line) in a manner similar to microglia of animal origin as shown by others. However human microglia release excessive amounts of ROS extracellularly, do not show excessive amounts of intracellular ROS and active caspases and most importantly do not show any protein aggregation or inclusion body formation. Human microglia appear to be resistant to rotenone (chronic, low

  11. Why we need new approaches to low-dose risk modeling

    SciTech Connect

    Alvarez, J.L.; Seiler, F.A.

    1996-06-01

    The linear no-threshold model for radiation effects was introduced as a conservative model for the design of radiation protection programs. The model has persisted not only as the basis for such programs, but has come to be treated as a dogma and is often confused with scientific fact. In this examination a number of serious problems with the linear no-threshold model of radiation carcinogenesis were demonstrated, many of them invalidating the hypothesis. It was shown that the relative risk formalism did not approach 1 as the dose approaches zero. When morality ratios were used instead, the data in the region below 0.3 Sv were systematically below the predictions of the linear model. It was also shown that the data above 0.3 Sv were of little use in formulating a model at low doses. In addition, these data are valid only for doses accumulated at high dose rates, and there is no scientific justification for using the model in low-dose, low-dose-rate extrapolations for purposes of radiation protection. Further examination of model fits to the Japanese survivor data were attempted. Several such models were fit to the data including an unconstrained linear, linear-square root, and Weibull, all of which fit the data better than the relative risk, linear no-threshold model. These fits were used to demonstrate that the linear model systematically over estimates the risk at low doses in the Japanese survivor data set. It is recommended here that an unbiased re-analysis of the data be undertaken and the results used to construct a new model, based on all pertinent data. This model could then form the basis for managing radiation risks in the appropriate regions of dose and dose rate.

  12. Radiation-induced apoptosis in SCID Mousespleen after a low-dose irration

    NASA Astrophysics Data System (ADS)

    Ohnishi, T.; Takahashi, A.; Ohnishi, K.

    Purpose: To estimate the effects of space radiation on health of space crews, we aimed to clarify whether pre-irradiation at a low-dose interferes in a p53-centered signal transduction pathway induced by radiation. By using a severe combined immunodeficiency (Scid) mouse defective DNA-PK activity, we examined the role of DNA-PK activity in radioadaptation induced by low-dose irradiation. Methodology: Specific pathogen free 5-week-old fe male mice of Scid and the parental mice (CB-17 Icr+/+) were irradiated with X-rays at 3.0 Gy 1, 2, 3 or 4 weeks after conditioning irradiation at 0.15, 0.30, 0.45 or 0.60 Gy. The mice spleens were fixed for immunohistochemistry 12 h after irradiation. Bax on formalin-fixed paraffin-embedded sections were stained by the avidin-biotin peroxidase complex method using HISTOFINE SAB-PO(R) kit (Nichirei Co., Tokyo, Japan). Apoptosis incidence in the sections was measured by staining with HE staining. Results: The frequency of Bax- and apoptosis -positive cells increased up to 12 h after irradiation at 3.0 Gy in the spleen of CB-17 Icr+/+ and Scid mice. However, they were not observed by irradiation with low dose at 0.15-0.60 Gy. When pre-irradiation at 0.45 Gy 2 weeks before challenging acute irradiation at 3.0 Gy was performed, Bax accumulation and apoptosis induced by irradiation at 3.0 Gy was depressed in the spleen of CB-17 Icr+/+ mice, but not Scid mice. Conclusions: These data suggest that DNA-PKcs (expressed in CB-17 Icr+/+, not Scid mice) might play a major role on radioadaptation induced by pre-irradiation at low dose in mice spleen. We expect that the present findings will provide useful information for the care of space crews' health.

  13. Low-dose ionising radiation and cardiovascular diseases--Strategies for molecular epidemiological studies in Europe.

    PubMed

    Kreuzer, Michaela; Auvinen, Anssi; Cardis, Elisabeth; Hall, Janet; Jourdain, Jean-Rene; Laurier, Dominique; Little, Mark P; Peters, Annette; Raj, Ken; Russell, Nicola S; Tapio, Soile; Zhang, Wei; Gomolka, Maria

    2015-01-01

    It is well established that high-dose ionising radiation causes cardiovascular diseases. In contrast, the evidence for a causal relationship between long-term risk of cardiovascular diseases after moderate doses (0.5-5 Gy) is suggestive and weak after low doses (<0.5 Gy). However, evidence is emerging that doses under 0.5 Gy may also increase long-term risk of cardiovascular disease. This would have major implications for radiation protection with respect to medical use of radiation for diagnostic purposes and occupational or environmental radiation exposure. Therefore, it is of great importance to gain information about the presence and possible magnitude of radiation-related cardiovascular disease risk at doses of less than 0.5 Gy. The biological mechanisms implicated in any such effects are unclear and results from epidemiological studies are inconsistent. Molecular epidemiological studies can improve the understanding of the pathogenesis and the risk estimation of radiation-induced circulatory disease at low doses. Within the European DoReMi (Low Dose Research towards Multidisciplinary Integration) project, strategies to conduct molecular epidemiological studies in this field have been developed and evaluated. Key potentially useful European cohorts are the Mayak workers, other nuclear workers, uranium miners, Chernobyl liquidators, the Techa river residents and several diagnostic or low-dose radiotherapy patient cohorts. Criteria for informative studies are given and biomarkers to be investigated suggested. A close collaboration between epidemiology, biology and dosimetry is recommended, not only among experts in the radiation field, but also those in cardiovascular diseases. PMID:26041268

  14. Responses of the Rat Basal Ganglia Neurotensin Systems to Low Doses of Methamphetamine

    PubMed Central

    Alburges, Mario E.; Hoonakker, Amanda J.; Cordova, Nathaniel M.; Robson, Christina M.; McFadden, Lisa M.; Martin, Amber L.; Hanson, Glen R.

    2014-01-01

    Rationale Administration of high doses of methamphetamine (METH) in a manner mimicking the bingeing patterns associated with abuse, reduces NT release and causes its accumulation and elevated NT levels in extrapyramidal structures by a D1 mechanism. The relevance of these findings to the therapeutic use of METH needs to be studied. Objectives The effect of low doses (comparable to that used for therapy) of METH on basal ganglia NT systems was examined and compared to high-dose and self-administration effects previously reported. Methods Rats were injected four times (2-h intervals) with either saline or low doses of METH (0.25, 0.50 or 1.00 mg/kg/s.c.). For the DA antagonist studies, animals were pretreated with a D1 (SCH23390) or D2 (eticlopride) antagonist 15 min prior to METH or saline treatments. Rats were sacrificed 5–48 h after last injection. Results METH at doses of 0.25 and 0.50, but not 1.00 mg/kg rapidly and briefly decreased NTLI concentration in all basal ganglia structures studied. In the posterior dorsal striatum, the reduction in NT level after low-dose METH appeared to be caused principally by D2 stimulation, but both D2 and D1 stimulation were required for the NT responses in the other basal ganglia regions. Conclusions A novel finding from the present study was that opposite to abuse-mimicking high doses of METH, the therapeutically relevant low-dose METH treatment reduced NT tissue levels likely reflecting an increase in NT release and a short-term depletion of the levels of this neuropeptide in basal ganglia structures. The possible significance is discussed. PMID:24522333

  15. Low-dose radiation, scientific scrutiny, and requirements for demonstrating effects.

    PubMed

    Møller, Anders Pape; Mousseau, Timothy Alexander

    2013-01-01

    Recent nuclear accidents have prompted renewed interest in the fitness consequences of low-dose radiation. Hiyama et al. provided information on such effects in the Japanese pale grass blue butterfly in a paper that has been viewed more than 300,000 times, prompting a barrage of criticism. These exchanges highlight the role of scrutiny in studies with potential effects on humans, but also raise questions about minimum requirements for demonstrating biological effects. PMID:23987799

  16. [Successful treatment of panarteritis nodosa with low-dose methotrexate therapy].

    PubMed

    Brody, M; Böhm, I; Biwer, E; Bauer, R

    1994-07-01

    We report on a 45-year-old male patient who presented a classic polyarteritis nodosa (PAN). The clinical course extended over 7 years. In spite of 2 years immunosuppressive therapy with azathioprine and methylprednisolone the course was progressive. Low-dose methotrexate therapy was the only treatment that controlled the disease, leading to rapid clinical and histopathological remission. In low concentrations methotrexate acts as an IL-1 inhibitor, and it obviously suppresses the pathogenetic mechanism of PAN. PMID:7928343

  17. Combination therapy with finasteride and low-dose dutasteride in the treatment of androgenetic alopecia.

    PubMed

    Boyapati, Ann; Sinclair, Rodney

    2013-02-01

    We report on a 47-year-old man who was initially treated with finasteride for androgenetic alopecia. Despite continuous treatment, after year 4 his hair density was not as good as at year 2, and low-dose dutasteride at 0.5 mg/week was added to the finasteride therapy. This resulted in a dramatic increase in his hair density, demonstrating that combined therapy with finasteride and dutasteride can improve hair density in patients already taking finasteride. PMID:22686691

  18. Data Integration Reveals Key Homeostatic Mechanisms Following Low Dose Radiation Exposure

    SciTech Connect

    Tilton, Susan C.; Matzke, Melissa M.; Sowa, Marianne B.; Stenoien, David L.; Weber, Thomas J.; Morgan, William F.; Waters, Katrina M.

    2015-05-01

    The goal of this study was to define pathways regulated by low dose radiation to understand how biological systems respond to subtle perturbations in their environment and prioritize pathways for human health assessment. Using an in vitro 3-D human full thickness skin model, we have examined the temporal response of dermal and epidermal layers to 10 cGy X-ray using transcriptomic, proteomic, phosphoproteomic and metabolomic platforms. Bioinformatics analysis of each dataset independently revealed potential signaling mechanisms affected by low dose radiation, and integrating data shed additional insight into the mechanisms regulating low dose responses in human tissue. We examined direct interactions among datasets (top down approach) and defined several hubs as significant regulators, including transcription factors (YY1, MYC and CREB1), kinases (CDK2, PLK1) and a protease (MMP2). These data indicate a shift in response across time - with an increase in DNA repair, tissue remodeling and repression of cell proliferation acutely (24 – 72 hr). Pathway-based integration (bottom up approach) identified common molecular and pathway responses to low dose radiation, including oxidative stress, nitric oxide signaling and transcriptional regulation through the SP1 factor that would not have been identified by the individual data sets. Significant regulation of key downstream metabolites of nitrative stress were measured within these pathways. Among the features identified in our study, the regulation of MMP2 and SP1 were experimentally validated. Our results demonstrate the advantage of data integration to broadly define the pathways and networks that represent the mechanisms by which complex biological systems respond to perturbation.

  19. Early onset life-threatening myelosuppression after low dose of intravesical thiotepa

    PubMed Central

    Agnelli, Giancarlo; Gresele, Paolo; de Cunto, Maria; del Favero, Albano

    1982-01-01

    Intravesical instillation of thiotepa is a popular treatment for localized bladder carcinoma. The drug can enter the systemic circulation, and such absorption may be enhanced by extensive tumour infiltration or by a recent tumour resection. A case is reported of early onset life-threatening pancytopenia following an unusually low dose of the drug in a patient who had undergone a recent tumour resection. PMID:6812036

  20. [The effect of extremely low doses of the novel regulatory plant proteins ].

    PubMed

    Krasnov, M S; Margasiuk, D V; Iamskov, I A; Iamskova, V P

    2003-01-01

    Searching and study on regulatory proteins, which can keep under control the scope of important processes as like as cell adhesion, proliferation, differentiation and morphogenesis, is an actual aim of the current biochemistry. Recently we have identified S-100 proteins in plants of following species: plantain (Plantago major L.), aloe (Aloe arborescens L.), and bilberry (Vaccinum myrtillus L.). Extraction and purification of S-100 proteins gotten from these plants were performed by the method we developed earlier for adhesion proteins of animal tissues. Homogeneity of the studied plant proteins was evaluated and confirmed by HPLC and SDS-electrophoresis in PAAG. Both, plant and animal proteins have appeared to be biologically active at extremely low doses. The tests were performed by adhesiometrical method in short-term tissue culture of mouse's liver in vitro. As a result it was established that the plant proteins insert a membranotropic effect being added in extremely low doses, corresponding to 10(-10)-10(-13) mg/ml. Keeping in mind that the plantain is well known remedy for wound protection and healing, in several experiments we studied the biological effect of plant S-100 proteins on animal cells. It was found that S-100 proteins obtained from plantain influences proliferation of human fibroblasts in vitro. It was found that after the treatment with this protein in low doses the cell growth rate increases essentially. PMID:12881977

  1. Proteomic Analysis of Low Dose Arsenic and Ionizing Radiation Exposure on Keratinocytes

    PubMed Central

    Berglund, Susanne R.; Santana, Alison R.; Li, Dan; Rice, Robert H.; Rocke, David M.; Goldberg, Zelanna

    2008-01-01

    Human exposure to arsenic and ionizing radiation occur environmentally at low levels. While the human health effects of arsenic and ionizing radiation have been examined separately, there is little information regarding their combined effects at doses approaching environmental levels. Arsenic toxicity may be affected by concurrent ionizing radiation especially given their known individual carcinogenic actions at higher doses. We found that keratinocytes responded to either low dose arsenic and/or low dose ionizing radiation exposure, resulting in differential proteomic expression based on 2DGE, immunoblotting and statistical analysis. Seven proteins were identified that passed a rigorous statistical screen for differential expression in 2DGE and also passed a strict statistical screen for follow-up immunoblotting. These included: α-enolase, epidermal-fatty acid binding protein, heat shock protein 27, histidine triad nucleotide-binding protein 1, lactate dehydrogenase A, protein disulfide isomerase precursor and S100A9. Four proteins had combined effects that were different than would be expected based on the response to either individual toxicant. These data demonstrate a possible reaction to the combined insult that is substantially different from that of either separate treatment. Several proteins had different responses than what has been seen from high dose exposures, adding to the growing literature suggesting that the cellular responses to low dose exposures are distinct. PMID:19294697

  2. Treatment of Severe Alopecia Areata: Combination Therapy Using Systemic Cyclosporine A with Low Dose Corticosteroids

    PubMed Central

    Lee, Deborah; Oh, Doo Jin; Kim, Jung Wook; Park, Sung Wook; Oh, Min Kyung; Sung, Ho Suk

    2008-01-01

    Background Combination therapy using cyclosporine A (CsA) together with low-dose corticosteroids has adequate efficacy with little toxicity for the treatment of severe alopecia areata (AA). Objective We wanted to evaluate the clinical efficacy of combination therapy using CsA with low-dose corticosteroid for the treatment of severe AA and we also wanted to determine the safe therapeutic concentration of CsA in the peripheral blood. Methods We treated 34 cases of severe AA with combination therapy for 24 weeks and we evaluated the efficacy at 12 and 24 weeks. We monitored the peripheral blood concentration of CsA to determine the therapeutic range of CsA that has the fewest side effects. Results Of the patients, 77.4% (n=24) and 22.6% (n=10) were classified in the responder and poor-responder groups, respectively. The mean trough concentration of CsA was 95.1 and 101.2 ng/ml in the responder and poor-responder groups, respectively. For the patients with side effects associated with CsA, the mean CsA concentration was 195.8 ng/ml. Conclusion We found that combination therapy with systemic CsA and low-dose corticosteroids effectively treats severe AA and this therapy results in a safe, therapeutic concentration of CsA in the peripheral blood. PMID:27303186

  3. An optimized colony forming assay for low-dose-radiation cell survival measurement

    SciTech Connect

    Zhu J.; Sutherland B.; Hu W.; Ding N.; Ye C.; Usikalu M.; Li S.; Hu B.; Zhou G.

    2011-11-01

    The aim of this study is to develop a simple and reliable method to quantify the cell survival of low-dose irradiations. Two crucial factors were considered, the same number of cells plated in each flask and an appropriate interval between cell plating and irradiation. For the former, we optimized cell harvest with trypsin, diluted cells in one container, and directly seeded cells on the bottom of flasks in a low density before irradiation. Reproducible plating efficiency was obtained. For the latter, we plated cells on the bottom of flasks and then monitored the processing of attachment, cell cycle variations, and the plating efficiency after exposure to 20 cGy of X-rays. The results showed that a period of 4.5 h to 7.5 h after plating was suitable for further treatment. In order to confirm the reliability and feasibility of our method, we also measured the survival curves of these M059K and M059J glioma cell lines by following the optimized protocol and obtained consistent results reported by others with cell sorting system. In conclusion, we successfully developed a reliable and simple way to measure the survival fractions of human cells exposed to low dose irradiation, which might be helpful for the studies on low-dose radiation biology.

  4. Mitochondrial hormesis links low-dose arsenite exposure to lifespan extension

    PubMed Central

    Schmeisser, Sebastian; Schmeisser, Kathrin; Weimer, Sandra; Groth, Marco; Priebe, Steffen; Fazius, Eugen; Kuhlow, Doreen; Pick, Denis; Einax, Jürgen W; Guthke, Reinhard; Platzer, Matthias; Zarse, Kim; Ristow, Michael

    2013-01-01

    Arsenite is one of the most toxic chemical substances known and is assumed to exert detrimental effects on viability even at lowest concentrations. By contrast and unlike higher concentrations, we here find that exposure to low-dose arsenite promotes growth of cultured mammalian cells. In the nematode C. elegans, low-dose arsenite promotes resistance against thermal and chemical stressors and extends lifespan of this metazoan, whereas higher concentrations reduce longevity. While arsenite causes a transient increase in reactive oxygen species (ROS) levels in C. elegans, co-exposure to ROS scavengers prevents the lifespan-extending capabilities of arsenite, indicating that transiently increased ROS levels act as transducers of arsenite effects on lifespan, a process known as mitohormesis. This requires two transcription factors, namely DAF-16 and SKN-1, which employ the metallothionein MTL-2 as well as the mitochondrial transporter TIN-9.1 to extend lifespan. Taken together, low-dose arsenite extends lifespan, providing evidence for nonlinear dose-response characteristics of toxin-mediated stress resistance and longevity in a multicellular organism. PMID:23534459

  5. Radiation Hormesis: Historical Perspective and Implications for Low-Dose Cancer Risk Assessment

    PubMed Central

    Vaiserman, Alexander M.

    2010-01-01

    Current guidelines for limiting exposure of humans to ionizing radiation are based on the linear-no-threshold (LNT) hypothesis for radiation carcinogenesis under which cancer risk increases linearly as the radiation dose increases. With the LNT model even a very small dose could cause cancer and the model is used in establishing guidelines for limiting radiation exposure of humans. A slope change at low doses and dose rates is implemented using an empirical dose and dose rate effectiveness factor (DDREF). This imposes usually unacknowledged nonlinearity but not a threshold in the dose-response curve for cancer induction. In contrast, with the hormetic model, low doses of radiation reduce the cancer incidence while it is elevated after high doses. Based on a review of epidemiological