Patent Number: 052218422
Section: claims

1. A method for calibrating dosimeter devices and the like comprising: positioning a number of said devices to be exposed to calibrated levels of radiation in a generally circular array within a first radiation sealable chamber;  positioning a calibration radiation source within a second radiation sealable chamber with the calibration radiation source positioned on the axis of the said circular array of devices;  sealing said first chamber and opening communication between the first and second chambers on the said axis;  moving the calibration radiation source along the axis to a position generally in the plane of the devices to irradiate said devices;  timing the period of exposure of said devices to said calibration radiation source;  returning the calibration radiation source to the second chamber thereby sealing the second chamber from radiation emission;  opening said first chamber; and  removing said devices.  a source rod carrying a source of radiation including shielding means above and below said source;  a shield around said source rod formed of two parts including an opening between said parts for directing radiation radially from said source;  an aluminum backscatter shield covering said opening and attached to said parts to define said opening;  a shielded housing surrounding said shield including a cylindrical chamber having a cylindrical wall spaced from said shield;  a turntable for rotating said shield to provide a 360 degree radiation pattern from said source, and means driving said turntable;  a dosimeter rack in said chamber positioned such that dosimeters in said rack are exposed to radiation from said radiation source; and  means driving said source rod axially between positions wherein said source of radiation is aligned with said opening and wherein said source is substantially completely shielded. 2. The method in accordance with claim 1 wherein said devices are positioned between back scatter shielding and said source when said source is in position to irradiate the devices. 3. The method in accordance with claim 2 wherein additional backscatter shielding defines an annular radiation path of conical cross-section extending from the source to said devices. 4. The method in accordance with claim 1 wherein the radiation source comprises a plurality of discrete sources longitudinally positioned on the axis of said circular array wherein said discrete sources may be selectively moved into position on the axis of the circular array to allow different levels of radiation. 5. A self-contained shielded calibrator/irradiator for calibrating dosimeters including a rod containing a radiation source, a shield surrounding said rod including an opening for directing radiation from said rod, a shielded housing defining a cylindrical chamber surrounding and spaced from said shield, means for driving said source rod axially in said shield between a first position wherein radiation from said radiation source is directed through said opening and a second position wherein said radiation source is substantially completely shielded, a cover including shielding means removably covering said cylindrical chamber, powered means for opening and closing said cover a turntable and, a cylindrical rack for holding said dosimeters located on said turntable and aligned with said opening such that radiation from said source will impinge upon said dosimeters and a carriage supporting said calibrator/irradiator. 6. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein said source rod includes a plurality of radiation sources and is movable axially to at least three positions, one position providing a higher dose of radiation, one position providing a lower dose of radiation and one position wherein said radiation sources are substantially completely shielded. 7. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein said shielded housing includes a cylindrical copper member adjacent the wall of said cylindrical chamber serving as a backscatter shield. 8. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein said housing and said carriage do not exceed about 35 inches in width and 54 inches in height with the lid open. 9. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein a turntable is included for rotating said cylindrical rack and said turntable is driven by an electric motor. 10. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein said means for driving said source rod includes a pneumatic power source. 11. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein electric motor means is provided for raising and lowering said cover. 12. A self-contained shielded calibrator/irradiator as claimed in claim 11 wherein interlock means is connected to said electric motor means and said means for driving said source rod such that said cover cannot be opened unless said source rod is in its position wherein said radiation sources are substantially completely shielded. 13. A self-contained shielded calibrator/irradiator as claimed in claim 5 wherein an attenuator assembly is provided including a sleeve movable over said opening to attenuate the radiation from said source rod when said rod is in a position wherein radiation is directed to said dosimeters. 14. A self-contained shielded calibrator/irradiator for irradiating dosimeters comprising: 15. A self-contained shielded calibrator/irradiator as claimed in claim 14 wherein said source rod includes a plurality of radiation sources and is movable axially to at least three positions, one position providing a higher dose of radiation, one position providing a lower dose of radiation and one position wherein said radiation sources are substantially completely shielded. 16. A self-contained shielded calibrator/irradiator as claimed in claim 14 wherein said shielded housing includes a cylindrical copper member adjacent the wall of said cylindrical chamber serving as a backscatter shield. 17. A self-contained shielded calibrator/irradiator as claimed in claim 14 wherein interlock means is connected to said electric motor means and said means for driving said source rod such that said cover cannot be opened unless said source rod is in its position wherein said radiation sources are substantially completely shielded. 18. A self-contained shielded calibrator/irradiator as claimed in claim 14 wherein an attenuator assembly is provided including a sleeve movable over said opening to attenuate the radiation from said source rod when said rod is in a position wherein radiation is directed to said dosimeters.