Patent Number: 062018523
Section: abstract

A variable attenuation apparatus for use with a radiation-blocking liquid and a radiation source having an attenuation chamber capable of containing a layer of the radiation-blocking liquid and an adjustment device for selectively metering the thickness of the layer of the radiation-blocking liquid, whereby changes in the thickness of the layer alter the radiation transmitted through the attenuation chamber. In one embodiment, an adjustment device includes a reservoir for holding the radiation-blocking liquid and a siphon connection device for allowing the transfer of the radiation-blocking liquid between the reservoir and the attenuation chamber, wherein the thickness of the layer in the attenuation chamber varies in response to changes in elevation of said reservoir, so that an increase in the thickness of the layer causes a drop in the radiation transmitted through the attenuation chamber. A substantially linear increase in the thickness of the layer in the attenuation chamber may yield a substantially exponential drop in the radiation dose rate transmitted through the attenuation chamber. A desired dose rate pattern, such as an exponential dose rate pattern, may be delivered by the apparatus. An adjustable irradiator system is presented, and a method for delivering varying temporal radiation dose rates is described.