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This paper presents two new rebinning algorithms for the reconstruction of three-dimensional (3-D) positron emission tomography (PET) data. A rebinning algorithm is one that first sorts the 3-D data into an ordinary two-dimensional (2-D) data set containing one sinogram for each transaxial slice to be reconstructed; the 3-D image is then recovered by applying to each slice a 2-D reconstruction method such as filtered-backprojection. This approach allows a significant speedup of 3-D reconstruction, which is particularly useful for applications involving dynamic acquisitions or whole-body imaging. The first new algorithm is obtained by discretizing an exact analytical inversion formula. The second algorithm, called the Fourier rebinning algorithm (FORE), is approximate but allows an efficient implementation based on taking 2-D Fourier transforms of the data. This second algorithm was implemented and applied to data acquired with the new generation of PET systems and also to simulated data for a scanner with an 18 [degrees] axial aperture. The reconstructed images were compared to those obtained with the 3-D reprojection algorithm (3DRP) which is the standard 'exact' 3-D filtered-backprojection method. Results demonstrate that FORE provides a reliable alternative to 3DRP, while at the same time achieving an order of magnitude reduction in processing time. Index Terms - Image reconstruction, medical imaging, positron emission tomography, X-ray transform.

Postharvest microbial spoilage due to suboptimal transportation and packaging conditions is a key concern for the South African tomato industry. This study investigated the influence of washing with tap water or aqueous disinfectant solutions (chlorinated and anolyte water) on the microbiological quality of tomatoes during storage after transportation in nonrefrigerated trucks along two supply routes when packaged in crates and boxes. Route 1 was 1,093 km from field to storage site, while route 2 was 1,057 km. During transport, the temperature in the trucks fluctuated between 16 and 28°C and the relative humidity between 25 and 94% for route 1, while for route 2, the temperature was between 16 and 30°C and the relative humidity between 28 and 71%. Tomatoes at the pink maturity stage were sampled, treated, and stored for 28 days (11°C). The tomato firmness before treatment was 24.8 N (box samples) and 17.4 N (crate samples) for route 1, whereas it was 22.1 N (box samples) and 20.2 N (crate samples) for route 2. Temperature fluctuation during transportation led to water condensation on tomato surfaces. Tomatoes treated with anolyte water showed the lowest microbial surface burden during storage, with mean aerobic plate counts (APC) of 2.9 log CFU/cm2, coliform counts (CC) of 1.1 log CFU/cm2, and fungal counts (FC) of 2.3 log CFU/cm2. Overall, of the total APC recorded during storage, anolyte-treated samples contributed 9% while chlorinated water–treated samples contributed 30%. Of the total CC, anolyte samples presented 3% while chlorinated water samples made up 12%, and of the total recorded FC, anolyte samples contributed 7% while chlorinated water samples made up 22%. Scanning electron microscopy imaging showed surface cracks, which enable microbial colonization in crate-transported tomatoes. A combination of anolyte treatment and box packaging during transport resulted in the best microbiological quality during storage. The findings of this investigation provide motivation for the adoption of anolyte water as a postharvest disinfection treatment in the tomato industry. [ABSTRACT FROM AUTHOR]

Background: Ginger (Zingiber officinale) has been used for long time due to its potential antimicrobial activity against diversity of microbial pathogens. Aims and Objectives: The study was carried out to investigate the bacteria pathogens found in digestive tract infections and assess antimicrobial activities of ginger extract to identified bacteria. Materials and Methods: Bacteriological studies were carried out on stool samples from 30 patients attending Muhoza health center. Different types of bacteria were isolated from stool samples of digestive tract infection patients by using various methods such culture, biochemical test and antimicrobial activity of ginger extracts was analyzed at INES-Ruhengeri in clinical microbiology laboratory. Results: Study findings showed isolated bacteria and antibacterial activity of Ginger. Isolated bacteria and their percentages including Escherichia coli (46.6%) which is the predominant isolated bacteria, Salmonella species (33.33%), Enterobacter spp (10.0%), Shigella spp (6.6%) and Citrobacter (3.33%) which is the least isolated bacteria. Antibacterial activity of ginger was seen on isolated bacteria, as ethanol and methanol were used for ginger oil extraction, the antibacterial activity of ginger extracts using ethanol was seen on isolated bacteria such us Citrobacter spp with 14 mm of inhibition zone, Shigella spp with 12 mm, Salmonella with 11.1 mm, E. coli with 9.5 mm and Enterobacter spp which was seen to be resistant to ginger extract using ethanol with 0.66mm of inhibition zone. For methanol extracts antibacterial activity was seen as follows: Citrobacter spp at 12 mm, Shigella spp at 11 mm, E. coli at 8 mm, salmonella spp at 6.1 mm, and Enterobacter spp with 5 mm. Enterobacter spp was seen to be the most resistant bacteria in both extracts. Conclusion: Ginger has shown to have an antibacterial activity on bacteria isolated from digestive tract infected patients. It can be used as a medicine to treat these infections. Number of researches should be done to be sure on this reality of antibacterial activity of ginger.

Positron emission tomography data are typically reconstructed with maximum likelihood expectation maximization (MLEM). However, MLEM suffers from positive bias due to the non-negativity constraint. This is particularly problematic for tracer kinetic modeling. Two reconstruction methods with bias reduction properties that do not use strict Poisson optimization are presented and compared to each other, to filtered backprojection (FBP), and to MLEM. The first method is an extension of NEGML, where the Poisson distribution is replaced by a Gaussian distribution for low count data points. The transition point between the Gaussian and the Poisson regime is a parameter of the model. The second method is a simplification of ABML. ABML has a lower and upper bound for the reconstructed image whereas AML has the upper bound set to infinity. AML uses a negative lower bound to obtain bias reduction properties. Different choices of the lower bound are studied. The parameter of both algorithms determines the effectiveness of the bias reduction and should be chosen large enough to ensure bias-free images. This means that both algorithms become more similar to least squares algorithms, which turned out to be necessary to obtain bias-free reconstructions. This comes at the cost of increased variance. Nevertheless, NEGML and AML have lower variance than FBP. Furthermore, randoms handling has a large influence on the bias. Reconstruction with smoothed randoms results in lower bias compared to reconstruction with unsmoothed randoms or randoms precorrected data. However, NEGML and AML yield both bias-free images for large values of their parameter.

Unlabelled: In the standard software for the Siemens high-resolution research tomograph (HRRT) positron emission tomography (PET) scanner the most commonly used segmentation in the μ -map reconstruction for human brain scans is maximum a posteriori for transmission (MAP-TR). Bias in the lower cerebellum and pons in HRRT brain images have been reported. The two main sources of the problem with MAP-TR are poor bone/soft tissue segmentation below the brain and overestimation of bone mass in the skull., Method: We developed the new transmission processing with total variation (TXTV) method that introduces scatter correction in the μ-map reconstruction and total variation filtering to the transmission processing., Results: Comparing MAP-TR and the new TXTV with gold standard CT-based attenuation correction, we found that TXTV has less bias as compared to MAP-TR. We also compared images acquired at the HRRT scanner using TXTV to the GE Advance scanner images and found high quantitative correspondence. TXTV has been used to reconstruct more than 4000 HRRT scans at seven different sites with no reports of biases., Conclusion: TXTV-based reconstruction is recommended for human brain scans on the HRRT.

Unlabelled: Many authors have reported the importance of motion correction (MC) for PET. Patient motion during scanning disturbs kinetic analysis and degrades resolution. In addition, using misaligned transmission for attenuation and scatter correction may produce regional quantification bias in the reconstructed emission images. The purpose of this work was the development of quality control (QC) methods for MC procedures based on external motion tracking (EMT) for human scanning using an optical motion tracking system., Methods: Two scans with minor motion and 5 with major motion (as reported by the optical motion tracking system) were selected from (18)F-FDG scans acquired on a PET scanner. The motion was measured as the maximum displacement of the markers attached to the subject's head and was considered to be major if larger than 4 mm and minor if less than 2 mm. After allowing a 40- to 60-min uptake time after tracer injection, we acquired a 6-min transmission scan, followed by a 40-min emission list-mode scan. Each emission list-mode dataset was divided into 8 frames of 5 min. The reconstructed time-framed images were aligned to a selected reference frame using either EMT or the AIR (automated image registration) software. The following 3 QC methods were used to evaluate the EMT and AIR MC: a method using the ratio between 2 regions of interest with gray matter voxels (GM) and white matter voxels (WM), called GM/WM; mutual information; and cross correlation., Results: The results of the 3 QC methods were in agreement with one another and with a visual subjective inspection of the image data. Before MC, the QC method measures varied significantly in scans with major motion and displayed limited variations on scans with minor motion. The variation was significantly reduced and measures improved after MC with AIR, whereas EMT MC performed less well., Conclusion: The 3 presented QC methods produced similar results and are useful for evaluating tracer-independent external-tracking motion-correction methods for human brain scans.

The high computational cost of data processing in volume PET imaging is still hindering the routine application of this successful technique, especially in the case of dynamic studies. This paper describes two new algorithms based on an exact rebinning equation, which can be applied to accelerate the processing of three-dimensional (3-D) PET data. The first algorithm, FOREPROJ, is a fast-forward projection algorithm that allows calculation of the 3-D attenuation correction factors (ACF's) directly from a two-dimensional (2-D) transmission scan, without first reconstructing the attenuation map and then performing a 3-D forward projection. The use of FOREPROJ speeds up the estimation of the 3-D ACF's by more than a factor five. The second algorithm, FOREX, is a rebinning algorithm that is also more than five times faster, compared to the standard reprojection algorithm (3DRP) and does not suffer from the image distortions generated by the even faster approximate Fourier rebinning (FORE) method at large axial apertures. However, FOREX is probably not required by most existing scanners, as the axial apertures are not large enough to show improvements over FORE with clinical data. Both algorithms have been implemented and applied to data simulated for a scanner with a large axial aperture (30 degrees), and also to data acquired with the ECAT HR and the ECAT HR+ scanners. Results demonstrate the excellent accuracy achieved by these algorithms and the important speedup when the sinogram sizes are powers of two.