Quantitative 1D diffraction signatures during dual detector scatter VOI breast CBCT

摘要

Dual detector VOI scatter CBCT is similar to dual detector VOI CBCT except that during the high resolution scan, the low resolution flat panel detector is also used to capture the scattered photons. Simulations show a potential use of scatter to diagnose suspicious VOIs. Energy integrated signals due to scatter (EIS_S) were computed for a specific imaging task involving a malignant lesion and was labelled as a hypothetical experiment (expt) result. The signal was compared to predictions (pred) using benign and malignant lesions. The AEIS,, = EIS_s|~(expt) - EIS_s|~(pred) displayed eye catching diffraction structure when the prediction calculation used a benign lesion. The structure occurred even when the phantom compositions were different for prediction and experiment calculations. Since the diffraction structure has a circularly symmetric behaviour because the tissues are amorphous in nature, the 2D AEIS_S patterns were transformed to 1D signals. The 1D signals were obtained by calculating the mean AEIS_S signals in rings. The mean pixel values were a function of the momentum transfer argument q = 47π sin(θ/2)/A which ranged from 12 to 46 nm~(-1). The 1D signals correlated well with the 2D profiles. Of particular interest were scatter signatures between q = 20 and 30 nm~(-1) where malignant tissue is predicted to scatter more than benign fibroglandular tissue. The 1D diffraction signatures could allow a better method to diagnose a suspicious lesion during dual detector scatter VOI CBCT.