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We have designed and built a small animal single photon emission computed tomography (SPECT) imaging system equipped with parallel-hole and multipinhole collimators and capable of circular or helical SPECT. Copper-beryllium parallel-hole collimators suitable for imaging the ~35 keV photons from the decay of (125)I have been built and installed to achieve(More)
Simultaneous imaging of multiple probes or biomarkers represents a critical step toward high specificity molecular imaging. In this work, we propose to utilize the element-specific nature of the X-ray fluorescence (XRF) signal for imaging multiple elements simultaneously (multiplexing) using XRF computed tomography (XFCT). A 5-mm-diameter pencil beam(More)
Volumetric modulated arc therapy (VMAT) has recently emerged as a new clinical modality for conformal radiation therapy. The aim of this work is to establish a methodology and procedure for retrospectively reconstructing the actual dose delivered in VMAT based on the pre-treatment cone-beam computed tomography (CBCT) and dynamic log files. CBCT was(More)
Volumetric cone-beam CT (CBCT) images are acquired repeatedly during a course of radiation therapy and a natural question to ask is whether CBCT images obtained earlier in the process can be utilized as prior knowledge to reduce patient imaging dose in subsequent scans. The purpose of this work is to develop an adaptive prior image constrained compressed(More)
I Introduction The most common method for handling transmission errors in computer networks is through the detection of errors and retransmission of the erroneous messages. This strategy has been called Automatic Repeat Repvest (ARQ). Various protocols have been established to achieve maximum possible utilization of avilable bandwidth in the most efficient(More)
Let U(R, S) denote the class of all m x n matrices of O's and l's having row sum vector R and column sum vector S. The interchange graph G (R, S) is the graph where the vertices are the matrices in U (R, S) and two vertices are adjacent provided they differ by an interchange. Two tight upper-bounds of the maximum degree l:l.(G(R, S)) are given. Furthermore,(More)