In capturing an image of a grid by an image detector, a measurement pixel that is not in the position of a specific point having a maximum or minimum value of an output signal is referred to as a first measurement pixel, and a measurement pixel that is in the position of the specific point is referred to as a second measurement pixel. The disposition of the first and second measurement pixels are determined so as to satisfy the following condition: fG/fN≠odd number, wherein fG is a grid frequency and fN is a Nyquist frequency of pixels; and in shifting the grid C times by one pixel, the number of the first measurement pixels is larger than that of the second measurement pixels at any time in the range of a cycle C of a repetition pattern appearing in the image.

In capturing an image of a grid by an image detector, a measurement pixel that is not in the position of a specific point having a maximum or minimum value of an output signal is referred to as a first measurement pixel, and a measurement pixel that is in the position of the specific point is referred to as a second measurement pixel. The disposition of the first and second measurement pixels are determined so as to satisfy the following condition: fG/fN≠odd number, wherein fG is a grid frequency and fN is a Nyquist frequency of pixels; and in shifting the grid C times by one pixel, the number of the first measurement pixels is larger than that of the second measurement pixels at any time in the range of a cycle C of a repetition pattern appearing in the image.

An image detector is disposed behind a grid. The image detector has normal pixels and measurement pixels. Out of a group of measurement pixels based on which an average value of dose measurement signals is calculated, a [C/D] number of measurement pixels are disposed or chosen in a cycle Z=(R×C)±D. Wherein, C represents a cycle of a repetition pattern appearing in an arrangement direction of X-ray transparent layers and X-ray absorbing layers in an X-ray image of the grid, and is represented in units of the number of pixels. R represents a natural number of 0 or more. D represents an integer less than the cycle C. [C/D] represents a maximum integer equal to or less than C/D. Provided that at least the [C/D] number of measurement pixels are shifted C occasions by one pixel, if D=1, the average value of the dose measurement signals is invariable without any variations.

An image detector is disposed behind a grid. The image detector has normal pixels and measurement pixels. Out of a group of measurement pixels based on which an average value of dose measurement signals is calculated, a [C/D] number of measurement pixels are disposed or chosen in a cycle Z=(R×C)±D. Wherein, C represents a cycle of a repetition pattern appearing in an arrangement direction of X-ray transparent layers and X-ray absorbing layers in an X-ray image of the grid, and is represented in units of the number of pixels. R represents a natural number of 0 or more. D represents an integer less than the cycle C. [C/D] represents a maximum integer equal to or less than C/D. Provided that at least the [C/D] number of measurement pixels are shifted C occasions by one pixel, if D=1, the average value of the dose measurement signals is invariable without any variations.

The present disclosure provides an automatic exposure control method, including: providing an object to be tested; providing an image sensor, including a photosensitive element array composed of a plurality of photosensitive elements arranged in an array, and the photosensitive element array includes at least a plurality of first photosensitive elements and a plurality of second photosensitive elements; turning on the radiation source, and the first readout signals on the first photosensitive elements are read after exposing the area to be tested for the first preset time; continuing the exposure for the second preset time, turning off the photosensitive elements and reading the second readout signals on the second photosensitive elements; acquiring the preset dose threshold of the area to be tested based on the second and first readout signals, and obtaining the remaining time to reach the preset radiation dose to control the exposure of the radiation source.

The invention relates to a method for estimating a dose administered by a radiology system provided with an X-ray source and a flat surface sensor, wherein (a) an X-ray image of the patient is acquired by the flat surface sensor; (b) the grey level of the pixel is determined at the centre of the X-ray image; (c) the kerma K is calculated, on the patient's entrance from the grey level, from the electrical charge passing through the X-ray tube during the patient's exposure time, the thickness of the patient's body along the axis of the X-ray beam and the distance between the X-ray source and the patient. This method of estimating dose can significantly reduce the margin of error on the dose administered.

A control apparatus that controls, using automatic exposure control of controlling a radiation generation apparatus by comparing a radiation dose from the radiation generation apparatus with a target dose, radiation imaging using radiation from the radiation generation apparatus, comprises a processing unit that executes image processing on a radiation image obtained by the radiation imaging; and a setting unit that sets, as the target dose used in the automatic exposure control, a dose which is changed in accordance with an image processing parameter for executing the image processing.

A control apparatus that controls, using automatic exposure control of controlling a radiation generation apparatus by comparing a radiation dose from the radiation generation apparatus with a target dose, radiation imaging using radiation from the radiation generation apparatus, comprises a processing unit that executes image processing on a radiation image obtained by the radiation imaging; and a setting unit that sets, as the target dose used in the automatic exposure control, a dose which is changed in accordance with an image processing parameter for executing the image processing.

A timer circuit for an X-ray imaging system having an X-ray generator used to generate images of a patient. The circuit includes a current sensor connected between a main power system and a circuit interrupter, wherein the circuit interrupter is also connected to the X-ray generator. The circuit also includes a timing device coupled between the current sensor and a control computer. The timing device is triggered when a current level detected by the current sensor exceeds an idle current level wherein X-rays are not generated by the X-ray generator. The timing device then measures a time period that the idle current level is exceeded. When the measured time period exceeds a predetermined time period by 10%, the circuit interrupter is activated to turn off current flow to the X-ray generator.

A timer circuit for an X-ray imaging system having an X-ray generator used to generate images of a patient. The circuit includes a current sensor connected between a main power system and a circuit interrupter, wherein the circuit interrupter is also connected to the X-ray generator. The circuit also includes a timing device coupled between the current sensor and a control computer. The timing device is triggered when a current level detected by the current sensor exceeds an idle current level wherein X-rays are not generated by the X-ray generator. The timing device then measures a time period that the idle current level is exceeded. When the measured time period exceeds a predetermined time period by 10%, the circuit interrupter is activated to turn off current flow to the X-ray generator.