Effect on Lesion Detectability of Proximity to Anatomical Boundaries in Emission Tomography

Abstract — In emission tomography (ET) comprising PET and SPECT, anatomical information derived from intra-patient coregistered CT or MR scans can be incorporated into the ET reconstruction. The increasing availability of PET-CT and SPECT-CT has engendered renewed interest in anatomical priors. Our interest is in exploring the efficacy of such side information for lesion detectability. In simulation studies we used an idealized model of anatomical side information incorporated into a SPECT MAP (maximum a posteriori) reconstruction, and a channelized Hotelling observer (CHO) whose performance emulates that of humans in such detection tasks. We observed that detectability appears to vary little with or without anatomical side information unless the lesion is tightly constrained by anatomical boundaries. Our preliminary studies thus imply a limited utility for anatomical side information for this task

Tensile Strength Analysis of Similar Plate with F.e.a. When Lap Welded Joint is Used

‘Welding', the simple and excellent process joining of two similar and dissimilar metals of plates and other structure.50% of gross national product of the country is related to welding .Almost everything is made of metal is welded. Welding process includes arc welding, gas welding, and resistance welding (40 total process of welding exist).The most important factor of welding operation is tensile strength of welding joint under variable environmental and working conditions. .So by the experimental and analytical testing is done by the study of overlap length size and gap size are to be selected to evaluate the welded joint of tensile strength. The range of parameters is selected from the literature. For greater accuracy and test of specimen by making of holding device which will the specimen by UTM machine.The result is obtained by experimentation compare with result is evaluated by simulation. By the simulation and experimental observation to fix the length of overlap size is 25mm for 5mm thick plate recommended for minimum gap size. This will give maximum tensile strength

TENSILE STRENGTH ANALYSIS OF SIMILAR PLATE WITH F.E.A. WHEN LAP WELDED JOINT IS USED

‘Welding’, the simple and excellent process joining of two similar and dissimilar metals of plates and other structure.50% of gross national product of the country is related to welding .Almost everything is made of metal is welded. Welding process includes arc welding, gas welding, and resistance welding (40 total process of welding exist).The most important factor of welding operation is tensile strength of welding joint under variable environmental and working conditions. .So by the experimental and analytical testing is done by the study of overlap length size and gap size are to be selected to evaluate the welded joint of tensile strength. The range of parameters is selected from the literature. For greater accuracy and test of specimen by making of holding device which will the specimen by UTM machine.The result is obtained by experimentation compare with result is evaluated by simulation. By the simulation and experimental observation to fix the length of overlap size is 25mm for 5mm thick plate recommended for minimum gap size. This will give maximum tensile strength

Fast Preconditioned Conjugate Gradient Reconstruction for 2D SPECT

Abstract — To be clinically useful, reconstruction in SPECT should be accomplished rapidly and also result in good image quality. Penalized likelihood methods are desirable in that they can easily incorporate system and noise models as well as prior information into an objective function. The reconstruction, computed by maximizing the objective, requires an iterative method, and this can be slow. One class of optimization methods that has been used for SPECT are gradient methods, wherein at each iteration, a search direction is established and the objective maximized along this direction. Of the many variants of gradient methods, preconditioned conjugate gradient (PCG) methods have shown promise for their speed. The speed for PCG depends on choice of a preconditioner. In this work, we follow the development in [1] for the derivation of fast preconditioners for a penalized weighted least-squares objective, but we add some approximations specific to SPECT. In particular, we make use of our knowledge of the nature of attenuation and depth-dependent blur in SPECT in designing the preconditioner. The resulting preconditioners lead to tremendous speedups for penalized weighted least-squares objectives, but are still not practical in that extensive computation is required just to obtain the preconditioner itself. With further approximations, however, the preconditioners become practical to compute and lead to enhanced reconstruction speed relative to using no preconditioner (conjugate gradient) or commonly used diagonal preconditioners. We show results for 2 cases: (1) Poisson noise, attenuation, and depth independent blur, and (2) same, but with depth dependent blur. Index Terms — Statistical Image Reconstruction, SPECT I