| 摘要 |
PURPOSE:To block leakage of X-rays outside an irradiating field passing a leaf gap in simple shape by providing plural leaves, and setting a virtual radiation source formed with the plate planes of those leaves at a point deviated by a significant value from the radiation source. CONSTITUTION:The X-ray 43x arriving at a generatrix 40l formed with the gap between the leaves 36a and 37a is comprised so as not to pass the gap linearly. X-rays 44x, 45x arriving at another generatrix 41l, 42l are comprised similarly. Assuming that the leaf gap is set at 0.1mm, and a plane separated far from the lower terminal radiation source 11 of a center leaf 36a is separated by 50cm from the radiation source, and thickness in a direction of line flux center axis 7 of the leaf 36a is 70mm, and the virtual radiation source 35 is set at a point separated by 60mm from the radiation source 11 on the line flux center axis 7, the X-ray 8 can be prevented from directly passing the leaf gap.
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