Method and device for X-ray exposure control
First Claim
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1. A method for limiting radiation applied to an object during irradiation of the object by means of a radiation source, comprising:
- retrieving a control curve for controlling the radiation source corresponding to a selected radiographic procedure, the control curve relating a first operating parameter of the radiation source to a second operating parameter of the radiation source;
retrieving a yield curve corresponding to characteristics of the radiation source, the yield curve relating the first parameter of the radiation source with dose as a function of the second parameter;
for each of a plurality of points along the retrieved control curve, using the yield curve to determine a patient radiation dose rate;
comparing the determined patient dose rate with a preselected maximum dose rate;
altering the retrieved control curve such that the patient dose rate is at or below the preselected maximum dose rate to create a corrected control curve;
using the corrected control curve to control the radiation source during the irradiation of the object such that the maximum dose rate is not exceeded during the irradiation.
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Abstract
The radiation applied to an object (input dose rate) during irradiation of the object by a radiation source (1) is limited during X-ray exposures. Pairs of values of a control curve which give rise to an input dose rate on the object to be examined which exceeds a predetermined maximum input dose rate are corrected by an arithmetic unit (76). This results in a corrected control curve whose entire length can be used for adjusting the desired tube parameters (tube voltage, tube current or load) without giving rise to the risk of exceeding the maximum input dose rate.
35 Citations
16 Claims
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1. A method for limiting radiation applied to an object during irradiation of the object by means of a radiation source, comprising:
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retrieving a control curve for controlling the radiation source corresponding to a selected radiographic procedure, the control curve relating a first operating parameter of the radiation source to a second operating parameter of the radiation source; retrieving a yield curve corresponding to characteristics of the radiation source, the yield curve relating the first parameter of the radiation source with dose as a function of the second parameter; for each of a plurality of points along the retrieved control curve, using the yield curve to determine a patient radiation dose rate; comparing the determined patient dose rate with a preselected maximum dose rate; altering the retrieved control curve such that the patient dose rate is at or below the preselected maximum dose rate to create a corrected control curve; using the corrected control curve to control the radiation source during the irradiation of the object such that the maximum dose rate is not exceeded during the irradiation. - View Dependent Claims (2, 3, 4, 5)
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6. A device for limiting radiation applied to an object during irradiation of the object by means of a radiation source, the device comprising:
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a first storage device which stores control curves each corresponding to a selectable radiographic procedure and at least one yield curve characteristic of at least, the radiation source; a programmable arithmetic unit for calculating a corrected control curve, the programmable arithmetic unit being programmed to perform the steps of; retrieving a stored control curve and yield curve; for each of a plurality of points along the retrieved control curve, using the retrieved yield curve to determine a patient radiation dose rate; comparing the determined patient dose rates with a preselected maximum dose rate; altering the retrieved control curve such that the patient dose rate is at or below the preselected maximum dose rate to create a corrected control curve; storing the corrected control curve in a second storage device; retrieving the corrected control curve from the second storage device; using the retrieved corrected control curve to control the radiation source during the irradiation of the object such that the maximum dose rate is not exceeded during the irradiation. - View Dependent Claims (7, 8, 9)
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10. A method for limiting radiation applied to an object during irradiation of the object by a radiation source, the method comprising:
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before irradiating the object, selecting a control curve for controlling the radiation source, the control curve corresponding to a selected irradiation process, the control curve being formed by a plurality of pairs of values which relate at least one first operating parameter of the radiation source with a second operating parameter of the radiation source; before irradiating the object, correcting the control curve in dependence on a yield curve which relates dose rate to the first and second operating parameters in such a manner that a preselected maximum dose rate is not exceeded for any of the pairs of values to generate a corrected control curve; and after generating the corrected control curve, controlling the radiation source during the selected irradiation process with the corrected control curve. - View Dependent Claims (11, 12, 13, 14)
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15. An apparatus for limiting radiation applied to an object during irradiation of the object by means of a radiation source, the apparatus comprising:
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means for selecting from a storage device a control curve for controlling the radiation source, the control curve formed by a plurality of pairs of values, the control curve relating at least one first operating parameter of the radiation source with a second operating parameter of the radiation source; a programmable arithmetic unit for calculating a corrected control curve which corrects the selected control curve in dependence on a yield curve which relates dose rate to at least one of a distance between the object and the radiation source, a radiation yield of the radiation source, and a filter disposed between the radiation source and the object in such a manner that a preselected maximum dose rate delivered to the patient is not exceeded for any of the pairs of values along the corrected control curve; and a means for controlling the irradiation source with the corrected control curve.
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16. A device for X-ray exposure control of an X-ray system comprising:
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an X-ray source for irradiating an object; a storage device for storing a plurality of control curves which each relate at least a first operating parameter of the X-ray source to a second parameter of the X-ray source for performing a selected irradiation procedure, at least one yield curve which relates a dose rate to the x-ray source and its operating conditions, and a corrected control curve; a programmable arithmetic unit for calculating the corrected control curve from the selected control curve and the yield curve such that a dose rate of the corrected control curve does not exceed a preselected maximum dose rate; and an automatic exposure control device for controlling a voltage supply unit for the X-ray tube in accordance with a measured dose rate applied to the object and the corrected control curve.
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Specification