Fast scan reset for a large area x-ray detector
AssigneeGeneral Electric Company
InventorsScott W. Petrick, Larry R. Skrenes, Jean Claude Morvan
Life of this patent
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Abstract
A large area solid state x-ray detector employs a plurality of cells arranged in rows and columns composed of photodiodes that are charged, exposed to x-rays which deplete their charge in proportion to the exposure, and then recharged to determine the amount of exposure. Fast scanning of the photodiodes consistent with the reduction of dark current effects is obtained without ghost images by employing a non-imaging scan following the imaging scan. The non-imaging scan employs a greater proportion of each scan duration for charge restoration than the imaging scan. In one embodiment simultaneous non-imaging recharging of the photodiodes is performed to substantially reduce this non-imaging time.
Claims12
An area x-ray detector producing repeated image signals at a frame rate comprising:
- (1) a plurality of electrically-chargeable solid state cells arranged in rows and columns;
- (2) charge integrators attached to the cells of each column to provide a reading of total charge delivered to the cells of each column;
- (3) acquisition control electronic circuitry programmed to:
- (a) acquire an image signal during a scan of each of the rows of cells, one row at a time, at a row rate, the scanning of each row including (i) charging the cells of the row for a first predetermined time period;
- (ii) measuring the total charge delivered to each cell of the row by means of the charge integrators;
- and (iii) resetting the charge integrators;
- and
- (b) restore the charge of cells of the detector during a scan of each of the rows of cells, one row at a time, at the row rate, the restoring of each row including charging the cells of the row for a second predetermined time period larger than the first predetermined time period.
An area x-ray detector producing repeated image signals at a frame rate comprising:
- (1) a plurality of electrically-chargeable solid state cells arranged in rows and columns;
- (2) charge integrators attached to the cells of each column to provide a reading of total charge delivered to the cells of each column;
- (3) acquisition control electronic circuitry programmed to
- (a) acquire an image signal during a scan of each of the rows of cells one row at a time at a row rate, the scanning of each row including (i) charging the cells of the row for a first predetermined time period (ii) measuring the total charge delivered to each cell of the row by means of the charge integrators;
- and (iii) resetting the charge integrators;
- and
- (b) restore the charge of a multiple of the cells of the detector simultaneously by charging the cells of a multiple of rows for a second predetermined time period.
A method of operating an area x-ray detector producing repeated image signals at a frame rate, the area x-ray detector including a plurality of electrically-chargeable solid state cells arranged in rows and columns with charge integrators attached to the cells of each column to provide a reading of total charge delivered to the cells of each column, the method comprising the steps of:
- (a) acquiring an image signal during a scan of each of the rows of cells, one row at a time, at a row rate, the scanning of each row including (i) charging the cells of the row for a first predetermined time period;
- (ii) measuring the total charge delivered to each cell of the row by means of the charge integrators;
- and (iii) resetting the charge integrators;
- and
- (b) restoring the charge of cells of the detector during a scan of each of the rows of cells, one row at a time, at the row rate, the restoring of each row including charging the cells of the row for a second predetermined time period larger than the first predetermined time period.
A method of operating a large area x-ray detector producing repeated image signals at a frame rate, the area x-ray detector including a plurality of electrically-chargeable solid state cells arranged in rows and columns with charge integrators attached to the cells of each column to provide a reading of total charge delivered to the cells of each column, the method comprising the steps of:
- a) acquiring an image signal during a scan of each of the rows of cells, one row at a time, at a row rate, the scanning of each row including (i) charging the cells of the row for a first predetermined time period;
- (ii) measuring the total charge delivered to each cell of the row by means of the charge integrators;
- and (iii) resetting the charge integrators;
- and
- b) restoring the charge of cells of the detector during a scan of multiple rows of cells, at one time, at the row rate;
- the restoring of multiple rows including charging the cells of multiple rows for a second predetermined time period.
Dependencies are inferred from the claim text.