Jianguo Qian

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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)
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)
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)
m Let R = (rl, r2, . . . , r,,) and S = (Sl,S2 ..... s,) be two positive integral vectors with }--~i=l ri = ~ j i sj=Nl. Denote by ~tl(R,S) the class of all m × n (0, 1)-matrices having row sum vector R and column sum vector S. The interchange 9raph G(R,S) is the graph where the vertices are the matrices in °//(R, S) and two vertices are adjacent provided(More)
A novel commercial medical linac system (TrueBeam™, Varian Medical Systems, Palo Alto, CA) allows respiratory-gated volumetric modulated arc therapy (VMAT), a new modality for treating moving tumors with high precision and improved accuracy by allowing for regular motion associated with a patient's breathing during VMAT delivery. The purpose of this work is(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)
PURPOSE To implement and evaluate clinic-ready adaptive imaging protocols for online patient repositioning (motion tracking) during prostate IMRT using treatment beam imaging supplemented by minimal, as-needed use of on-board kV. METHODS The authors examine the two-step decision-making strategy: (1) Use cine-MV imaging and online-updated characterization(More)
A generalization of Sperner’s theorem is established: For a multifamily M = {Y1, . . . , Yp} of subsets of {1, . . . , n} in which the repetition of subsets is allowed, a sharp lower bound for the number φ(M) of ordered pairs (i, j) satisfying i 6= j and Yi ⊆ Y j is determined. As an application, the minimum average distance of orientations of complete(More)
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 manner(More)