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(a) Photograph detailing the basic structure inside the compact microbeam irradiator Also shown are indicators for electron trajectories from the cathode assembly (light blue), the location of the segmented focal line on the anode (red), X-ray photon trajectories from the anode (light green), and the projected focal line image on the window (yellow). (b)Diagram (as seen from cathode assembly) showing how the multiple line segments produce microbeam paths that irradiate a sample from different angles. For another illustration of how microbeams are created from our source, see Figure 4(b) .
(a) Solidworks™ diagram showing linear array of cathodes used in the compact MRT device. (b) Diagram illustrating the entire cathode assembly and the linear focusing track. (c) Cross section through the assembly showing the internal components and the focusing geometry used.
(a) Simulation results displaying 1.02 mm focal line width given the geometrical setup of our cathode assembly and focusing structure. (b) Graph displaying maximum anode temperature given five simultaneous 75 mA pulses of varying widths. Note that the maximum temperature reached using a 0.1 ms pulse is well below the melting temperature of molybdenum.
(a) Solidworks™ diagram showing the structure of the collimator alignment system. Notice the rotational and translational degrees of freedom necessary for alignment. (b) Diagram illustrating how the collimator selects out a microplane from the wedge of radiation that emanates from the focal line. The angle of this wedge to the face of the anode is set by angle blocks holding the collimator within its housing.
Graph displaying cathode stability over multiple days of use with horizontal axis divided into hours for each day. Notice that the voltage required to produce a constant 46.5 mA of cathode current does not appreciably change between days and only increases during usage, recovering after long breaks in use.
(a) Solidworks™ cross section of the entire device design displaying the target location beneath the anode, X-ray window, and collimator assemblies. (b) Sample irradiated film and beam profile displaying the peak dose achieved in 8 min of irradiation and width of the microbeam created.
(a) Irradiated film and dose profile displaying our peak to valley dose ratio given a center to center separation of 1.4 mm between the microbeams. (The intensity variation seen here is due to slight non-uniformity in focal line position and collimator transmission under tube heating during continual use.) (b) Histological image of microbeam DNA damage in a mouse brain. Cell staining was done with γ-H2AX labeling, and the peak entrance dose given was 13 Gy per microbeam.
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