• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.1-7
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• 2007

Carbon monoxide (CO) is not only an important intermediate species in chemical reaction mechanisms of hydrocarbon fuel combustion, but also a crucial pollutant species emitted from automotive engines. To better understand the physical processes impacting CO emissions, the development of laser-based measurement techniques that can visualize in-cylinder CO distributions is desirable. Among these techniques, Laser-Induced Fluorescence (LIF) is a sensitive and species-selective detection technique capable of good spatial resolution. However, some technical matters such as deep UV excitation, severe pressure dependency of the LIF signal, and potential interference from other species have been major challenges for CO LIF application. This study is focused on investigating the feasibility of CO two-photon LIF in a direct-injection diesel engine operating at typical pressure and temperature conditions with commercial grade diesel fuel. Spectroscopic analysis shows that the CO fluorescence signal can be separated from $C_2$ Swan band or broadband fluorescence from PAHs when the signal is collected near 483 nm. The signal-to-noise ratio of CO LIF deteriorate rapidly as pressure is increased, following $P^{-1.49}$ which matches the theoretical signal pressure dependency.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.2
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• pp.67-74
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• 2009

Purpose: To evaluate the results of absorbed and effective doses using two different modes, standard mode (A-mode) and low-dose mode (B-mode) settings for prostate cancer IGRT from CBCT. Materials and Methods: This experimental study was obtained using Clinac iX integrated with On Board Imager (OBI) System and CBCT. CT images were obtained using a GE Light Speed scanner. Absorbed dose to organs from ICRP recommendations and effective doses to body was performed using A-mode and B-mode CBCT. Measurements were performed using a Anderson rando phantom with TLD-100 (Thermoluminescent dosimeters). TLD-100 were widely used to estimate absorbed dose and effective dose from CBCT with TLD System 4000 HAWSHAW. TLD-100 were calibrated to know sensitivity values using photon beam. The measurements were repeated three times for prostate center. Then, Evaluations of effective dose and absorbed dose were performed among the A-mode and B-mode CBCT. Results: The prostate absorbed dose from A-mode and B mode CBCT were 5.5 cGy 1.1 cGy per scan. Respectively Effective doses to body from A mode and B-mode CBCT were 19.1 mSv, 4.4 mSv per scan. Effective dose from A-mode CBCT were approximately 4 times lower than B-mode CBCT. Conclusion: We have shown that it is possible to reduce the effective dose considerably by low dose mode(B-mode) or lower mAs CBCT settings for prostate cancer IGRT. Therefore, we should try to select B-mode or low condition setting to decrease extra patient dose during the IGRT for prostate cancer as possible.