Image filtering consists of modifying the original image by logically "reimaging" it with a mathematical imaging device in which spatial response can be controlled by the user. Image filtering is performed by a mathematical operation called convolution, which is simply the successive replacement of each point in the original image by a new value produced by a weighted combination of the original point and its surrounding neighbour points. Filtering generally requires definition of a filtering kernel or small matrix; often a few filtering kernels are predefined in imaging computer systems. The filtering kernel is generally square with a matrix size of 3×3 pixels, 5×5 pixels or 7×7 pixels. We consider the use of two-dimensional, second-order derivatives for image enhancement. The approach basically consists of defining a discrete formulation of the second-order derivative and then constructing a filter mask based on that formulation. Ten spatial high-pass filters (masks) are developed, then implemented and tested in our laboratory by using programs that were written in Borland c ++ and visual Fortran. The results of the application of the developped Laplacian and Laplacian high-pass digital filters (masks) on digital images (either edge detection, sharpening of high frequency regions (fine details) accentuation), comparing between the effect of different dimensions filters 3×3 and 5×5 and milder high pass effect are presented and demonstrated. As the size of the filter (mask) gets larger and/or the weight of the center pixel of the kernel gets higher, the sharpenning effect becomes more and more. Second-order derivatives have a strong response to fine detail, such as thin lines and isolated points.

Radioiodine (iodine-131, or I-131) therapy has been used successfully for thyroid therapy for more than 50 years. Protocols for treatment with I-131 differ from country to country and even from hospital to hospital in the same country. Daily area surveys of hallways, stairwells, and rooms adjacent to isolation rooms must be conducted and documented to ensure that doses to any individuals in unrestricted areas do not exceed 20 mcSv (2 mrem) in one hour. Nursing and housekeeping staffs must realize that once therapy has begun, no items are to be removed from the room unless first cleared by nuclear medicine or radiation safety personnel. With proper education and instructions for patients and their family members, radiation exposure to healthcare professionals and the general public can be minimized. The objectives of this article are to review (a) practical radiation safety concerns associated with hospitalized patients receiving I-131 therapy, (b) preventive measures to minimize potential exposure and contamination problems, and (c) radiation safety precautions and preventive measures to minimize radiation exposure to family members and helpers living with patients receiving outpatient I-131 therapy.

99m Tc-mebrofenin hepatobiliary scintigraphy has been introduced for the noninvasive assessment of liver function in the clinical setting and in experimental research. Methods: During a period of 2 y, 15 patients with fatty livers diagnosed as having nonalcoholic steatohepatitis underwent hepatobiliary scintigraphy using the radiopharmaceutical agent 99m Tc-labeled mebrofenin. After intravenous administration of 85 MBq of 99m Tc-mebrofenin, a dynamic image was acquired with the liver and heart in the field of view. In this study, a comparison between the values of hepatic uptake rate obtained by applying 2 methods in patients with nonalcoholic steatohepatitis-multiple-time graphical analysis (Gjedde-Patlak plot) and the differentiation between different regions of interest using hepatobiliary scintigraphy-was made. Results: The values of the uptake rate reveal that uptake obtained by applying the second method are significantly higher than that obtained by applying the first one (P 5 0.001). A strong positive association (n 5 15; r 5 0.92; R 2 5 0.84) was found between these measurements. From a Bland-Altman statistical test that was performed on the results we also found that 87% of the cases (13/15) were within 1.96 SD. Conclusion: The Gjedde-Patlak analysis method can be considered as an alternative technique to find and calculate the hepatic uptake rate.

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