Томографічна реконструкція «великих» об’єктів при використанні часткових сканувань

Представлено алгоритми томографічної реконструкції «великих» об’єктів. Розглянуто випадки використання часткових сканувань горизонтальних і вертикальних секцій при розмірах об’єктів, що в декілька разів перевищують кут конусного променя та розміри матриці детекторів. Наведено результати моделювання томографічної реконструкції математичних фантомів.Представлены алгоритмы томографической реконструкции «больших» объектов. Рассмотрены случаи использования частичных сканирований горизонтальных и вертикальных секций при размерах объектов, в несколько раз превышающих угол конусного луча и размеры матрицы детекторов. Приведены результаты моделирования томографической реконструкции математических фантомов.The tomographic reconstruction algorithms for «large» objects are presented. The cases of using partial scans of horizontal and vertical sections if the objects sizes are greater by several fold than the angle of cone-beam and the matrix detector sizes are considered. The results of the tomographic reconstruction modeling using the mathematical phantoms are given

Detection, 3-D positioning, and sizing of small pore defects using digital radiography and tracking

This article presents an algorithm that handles the detection, positioning, and sizing of submillimeter-sized pores in welds using radiographic inspection and tracking. The possibility to detect, position, and size pores which have a low contrast-to-noise ratio increases the value of the nondestructive evaluation of welds by facilitating fatigue life predictions with lower uncertainty. In this article, a multiple hypothesis tracker with an extended Kalman filter is used to track an unknown number of pore indications in a sequence of radiographs as an object is rotated. Each pore is not required to be detected in all radiographs. In addition, in the tracking step, three-dimensional (3-D) positions of pore defects are calculated. To optimize, set up, and pre-evaluate the algorithm, the article explores a design of experimental approach in combination with synthetic radiographs of titanium laser welds containing pore defects. The pre-evaluation on synthetic radiographs at industrially reasonable contrast-to-noise ratios indicate less than 1% false detection rates at high detection rates and less than 0.1 mm of positioning errors for more than 90% of the pores. A comparison between experimental results of the presented algorithm and a computerized tomography reference measurement shows qualitatively good agreement in the 3-D positions of approximately 0.1-mm diameter pores in 5-mm-thick Ti-6242