Generic vibration criteria for vibration-sensitive equipment
The vibration criterion (VC) curves, commonly used in the design of facilities which house vibration-sensitive instruments and tools, were developed by the author and his colleagues, in the early 80's, published by SPIE in 1991 and by IEST in 1993. Each of the criterion curves A through E is associated with a 'line width' or 'detail size' which was an attempt by the authors to describe the capabilities of the tools with which each curve might be associated. In the years since the curves were developed there have been substantial developments in tool design and isolation. In this paper the curves are reviewed in the context of present-day tools and processes. Changes are proposed where these might be justified.
The effect of vibration generated by demolition work on irradiation position accuracy of stereotactic radiotherapy system
Abstract Purpose One existing building, adjacent to the radiotherapy building, where stereotactic radiation was done, was to be demolished to give space for the construction of a new building. However, we were concerned that the vibrations generated by this demolition work, which occurred within 2 m from the radiotherapy building, would affect the radiation position accuracy of the radiotherapy machine. Methods To determine whether radiotherapy could be performed safely during the demolition period, we performed simulation tests involving the vibrations generated during demolition, measured these vibrations, and verified their effect on the irradiation position accuracy of the stereotactic radiotherapy system. For effective evaluations, tests were conducted assuming the maximum vibrations that could occur during actual demolition work. Results The maximum displacement of the vibrations generated by the simulated demolition work was 3.30 µm on the floor of the treatment room and 4.68 µm at the ceiling. Conclusions The results of the vibration measurements exceeded the limits of the criteria applicable to the electron beam system. However, the accuracy of the irradiation position of the stereotactic radiotherapy system remained unchanged during these vibrations. Therefore, the vibrations had no impact on radiotherapy safety, and radiotherapy was continued during the demolition work while coordinating with the demolition workers as necessary.
The Design Of Low-Vibration Buildings For Microelectronics And Other Occupancies
In this paper I present an overview of the factors and problems that must be considered in designing low-vibration buildings. Subjects covered include vibration criteria for different occupancies; sources of vibration and response predictions; major design factors for vibration control.