Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Reexamination Certificate
1999-06-09
2001-06-19
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
C209S542000, C209S544000
Reexamination Certificate
active
06248968
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for assaying radioactive seeds used in medical applications.
BACKGROUND OF THE INVENTION
Assaying of radioactive seeds is usually done by selecting a number of samples from a batch of seeds, and then checking each of the selected seeds for either or both of equatorial anisotropy (EA) and for level of radioactivity. This checking is performed manually by a person with the aid of conventional radiation counting equipment. Decisions concerning the suitability of the batch are made based on the samples tested. If there is a serious question concerning the batch, then each seed is individually manually tested. Each seed is a radioactive sealed source in the form of an elongated seed.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method and apparatus for automatically checking radioactive seeds in a batch to determine either or both EA and level of radioactivity, and then sorting the seeds according to the sensed assay information. In a specific embodiment, the method of the present invention includes the steps of feeding the seeds from a hopper one at a time (single file) along a conveying path in a fixed geometry, usually in the direction of their long axes. The seeds are moved to an EA measuring station, rotated in front of the EA test apparatus, moved to a dose calibration station, and based on nuclear count or radioactive activity, the seeds are moved to proper or preselected ones of a plurality of storage bins (up to 25), including a discard bin for seeds which are outside the specification range.
The foregoing method is accomplished by the present invention by apparatus including a storage bin to hold the seeds, and feeding the seeds by gravity out of the storage bin one at a time using a vibratory feeder, with or without an air assist to help fluidize the seeds. The seeds are introduced one at a time into a station for measuring EA. The feed into and out of the EA station is controlled by gates and photosensors, under the control of a microprocessor which also controls the vibratory feeder. EA measurements are taken by incrementally rotating an individual seed about its longitudinal axis. The incremental movement may be any preselected number of degrees of angular movement. Movements in the range of 30 to 60 degrees are preferred. At the end of each movement, a counting instrument takes a reading, which is fed to the microprocessor. At the end of the movements, that is when 360 degrees rotation has been effected, a decision is made whether to advance or discard the seed. If advanced, the seed feeds by gravity with or without an air assist, to the dose station. If discarded, the seed goes directly to a discard vial at the turret station. At this dose station, equipped with photosensors and gates, the level of radioactivity of the seed is measured. If the seed measures as having high activity, the seed is measured in both its 180 degree longitudinal orientations, to detect polar differences. The seed at the dose station is placed into, preferably lifted into, a radioactivity level counting instrument which feeds its output to the microprocessor. If the seed is not to be discarded, it is advanced to a turret wheel, provided with photosensors, which contains a plurality, 10-25, of receptacles, called pigs, and it is dropped via a funnel into the appropriate receptacle selected by the microprocessor based on the measurements taken for the particular seed. If discarded, the seed goes to a discard receptacle in the turret wheel. The apparatus is equipped with the appropriate motors, lift mechanism, photosensors, gates and controls.
Other and further objects and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention when taken in conjunction with the appended drawing.
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Dell Mary Anne
Gray James W.
Suzuki Arata
Suzuki Marcia
Capintec Inc.
Fleit Martin
Schlak Daniel K.
Suzuki Marcia
Walsh Donald P.
LandOfFree
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