| 摘要 |
An autoradiography system for obtaining exposures from, and reading the latent image stored in, stimulable phosphor foils includes a cassette which receives a preparation of low energy radiation emitting tissue to be examined and two stimulable phosphor foils separated by a shielding plate consisting of material permeable to high energy radiation, but impermeable to low energy radiation. The cassette is surrounded by a high radiation absorbing housing. The preparation is disposed against one of the foils, so that the low energy radiation therefrom forms a latent image on the adjacent foil, but cannot pass through the shielding plate to form an image on the other foil. Both foils will, however, record and form a latent image of high energy radiation which may not be absorbed by the cassette housing. One of the foils thus exhibits a latent image due solely to background or thermal radiation, while the other phosphor foil has a latent image corresponding to the tissue, as well as the background and thermal radiation. A processing circuit is included in a read out system having a subtraction stage which subtracts electronic signals corresponding to the two latent images from each other, so that a tissure image free of background and thermal radiation noise is obtained. Insensitivity to thermal noise is obtained by insulating and cooling the cassette.
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