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2. 10-MV X-ray dose calculation in water for MLC and wedge fields using a convolution method with X-ray spectra reconstructed as a function of off-axis distance

Author

Kamimura K, Saitoh H, Miyazawa M, Yoichiro Hosokawa, Seino M, Takagi M, Sasamori M, Fumio Komai, Shingo Terashima, Kimura S, Sutoh K, and Iwasaki A

Subjects
Optics, X ray dose, business.industry, convolution method, X-ray spectra, dose kernels, wedge, multileaf collimation, MLC leaf-field output subtraction, lcsh:R, lcsh:Medicine, Function (mathematics), business, Axis distance, Wedge (geometry), X ray spectra, Mathematics, Convolution
Abstract

Purposes: This paper highlights a 10-MV X-ray convolution dose calculation method in water using primary and scatter dose kernels formed for energy bins of X-ray spectra reconstructed as a function of the off-axis distance for a linear accelerator equipped with pairs of upper and lower jaws, a multileaf collimator (MLC) and a wedge filter. Methods: The reconstructed X-ray spectra set was composed of 11 energy bins. To estimate the in-air beam intensities at points on the isocenter plane for an MLC field, we employed an MLC leaf-field output subtraction method, using an extended radiation source on each of the X-ray target and the flattening filter as well as simplified two-dimensional plates to simulate the three-dimensional jaws and MLC structures. A special correction factor was introduced for nonuniform incident beam intensities, particularly produced at MLC fields. The in-phantom dose calculation was performed by treating the phantom, the wedge filter, the wedge holder and the MLC as parts of a unified irradiated body, where we proposed to use a special factor for the density scaling theorem within the unified irradiated body. Conclusions: The phantom dose was generally separated into nine dose-components: The primary and scatter dose-components produced in the phantom; the primary and scatter dose-components emanating from the wedge, the wedge holder and the MLC; and the electron contamination dose-component. From the calculated and measured percentage depth dose (PDD) and off-center ratio (OCR) datasets, we may conclude that the convolution method can achieve accurate dose calculations even under MLC and/or wedge filtration.

Published
2017

3. A low temperature coefficient optomodulator for analog signal transmission

Author

Ohska, T.K., Sasaki, O., Murakami, T., Doi, M., and Seino, M.

Subjects
Modulators (Electronics) -- Research, Signal processing -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A Mach-Zehnder type optomodulator has been investigated for the last quarter of a century, but its application for analog signal transmission in a physics experiment is a quite new idea. Recent studies have proven that Mach-Zehnder type optomodulators have a good potential in such applications. It will enable more than an order of magnitude reduction of cable volume and will be free from noise pickup and cross talk. Almost no attenuation through a long signal path in light fibers is also an asset when a detector size is very large. Power consumption is also minimal. If it does not have too large a temperature coefficient, it could be an excellent device for future experiments. We have studied its temperature coefficient and developed a unit that has low enough temperature coefficient so that it could be used for some physics experiments. A light wavelength of 1.55 micron was chosen for the unit.

Published
1993

16. A Novel Beat Noise Reduction Method for AOTF

Author

Nakazawa, T., primary, Sugiyama, M., additional, Doi, M., additional, Taniguchi, S., additional, Takasu, Y., additional, Hashimoto, N., additional, Norimatsu, M., additional, Han, W., additional, Miyata, H., additional, Satake, T., additional, Moroboshi, Y., additional, and Seino, M., additional

Published
2000
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19. AOTF for Optical ADM Systems

Author

Nakazawa, T., primary, Doi, M., additional, Taniguchi, S., additional, Takasu, Y., additional, Hashimoto, N., additional, and Seino, M., additional

Published
1999
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