METHOD AND SYSTEM FOR DYNAMICALLY ESTABLISHING FIELD SIZE COINCIDENCE

摘要

A method of establishing coincidence between a field size of alight field used in a setup mode of a radiation system and a field size of aradiation field used in an operation mode of the system includes providingautomatic adjustment of field-defining structure to compensate for differencesin optical properties of the light and the radiation. A light beam passingthrough the field-defining structure typically exhibits greater scatteringthan anX-ray beam passing through the structure. For each of a number of differentsettings of the field-defining structure, the difference between the fieldsizesof the light and the radiation are determined and recorded. Then, for aparticular desired field size, the field-defining structure can beautomaticallyadjusted to provide compensation. In the preferred embodiment, the field-defining structure includes jaws of a collimator of a radiation system and thedetermination of field size differences of the light and the radiation occursforeach of various energy level settings of the radiation system.