Changkai Wang

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The calibration of a catheter-based system to be used for therapeutic radiation treatment to prevent restenosis following interventional coronary procedures is described. The primary dosimetry was performed ionometrically using an extrapolation chamber equipped with a 1-mm diameter collecting electrode to measure absorbed dose in tissue equivalent plastic(More)
Accelerator-based intense epithermal neutron sources for Neutron Capture Therapy (NCT) have been considered as an alternative to nuclear reactors. Lithium (Li) has generally received the widest attention for this application, since the threshold energy is low and neutron yield is high. Because of the poor thermal and chemical properties of Li and the need(More)
Successful radiotherapy requires accurate dosimetry for treatment verification. Existing dosimeters such as ion chambers, TLD, and diodes have drawbacks such as relatively long measurement time and poor spatial resolution. These disadvantages become serious problems for dynamic-wedged beams. Thus the clinical use of dynamic wedges requires an improved(More)
A method of film dosimetry for high energy photon beams is proposed which reduces the required film calibration exposures to a set of films obtained for a small radiation field size and shallow depth (6 cm x 6 cm at 5 cm depth). It involves modification of a compression type polystyrene film phantom to include thin lead foils parallel to the vertical film(More)
Board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this study, some drop testing results were summarized based on our previous board-level drop tests. And then the finite element modeling and simulation were conducted to investigate and understand the drop reliability(More)
Full waveform data recording the reflected laser signal from ground objects have been provided by some commercial airborne LIDAR systems in the last few years. Waveform data enable users to explore more information and characteristics of the earth surface than conventional LIDAR point cloud. An important application is to extract extra point clouds from(More)
An accelerator-based neutron irradiation facility (ANIF), which has been proposed for BNCT, is based on a 2.5-MeV proton beam bombarding a thick lithium target. Neutrons which are emitted from the lithium target are too energetic for BNCT and must be moderated. A calculational study, which was done previously on the moderator assembly for an ANIF, shows(More)
We have developed a new detection method for measuring distributions of energy depositions from particles characterized by low linear energy transfers (LETs). In particular, we have developed a detection system to measure energy depositions produced by electrons and photons on nanometer scales. The detector is based upon the operational principles of the(More)
This study is concerned with dose measurement of photon beams, both dynamic and static, by using x-ray film. As discussed in our last study (Burch et al 1997, Yeo et al 1997), x-ray film, as an integrating dosimeter, can be an ideal candidate if the over-response problem to low-energy photons (energies below 400 keV) is solved. In summary, the problem of(More)