Method for servoing a source of X-rays of a digital radiography device
The invention relates to a radiographic device and method of servoing an X-ray source ( 800 ) in a radiography device comprising a MOS-type image sensor ( 810 ) with pixels provided with separate read and refreshment commands, respectively, in which, during a radiography operation, read commands of a plurality of image sensor pixels are called repeatedly, while maintaining a source of X-rays power-supplied, so as to establish, in response to each reading, at least one image acquisition characteristic, and in which the emission of X-rays is interrupted when the image acquisition characteristic corresponds to a preset image acquisition characteristic.
1. A method of servoing an X-ray source ( 800 ) in a radiography device comprising:
calling repeatedly during a radiography operation, read controls of a plurality of image sensor pixels provided via a MOS-type image sensor ( 810 ) with pixels ( 10 ) with separate read ( 30 ) and refreshment ( 20 ) controls, respectively;
maintaining a source of X-rays power supplied, to establish, in response to each reading, at least one image acquisition characteristic; and
interrupting the emission of X-rays upon the image acquisition characteristic corresponding to a preset image acquisition characteristic.
2. The method according to claim 1 , wherein the image acquisition characteristic is a histogram.
3. The method according to claim 2 , wherein the preset characteristic has histogram shape, and, in particular, a histogram shape centered on at least one from among the peaks ( 501 , 502 , 503 , 504 , 601 , 602 , 603 , 604 , 703 , and 704 ) characteristic of soft tissue, bone and dentine, enamel and opaque materials.
4. The method according to claim 1 , wherein the image acquisition characteristic is a number of pixels corresponding to at least one image density value.
5. The method according to claim 1 , wherein the image acquisition characteristic is a spreading of the density spectrum exceeding a threshold value.
6. The method according to claim 1 , wherein read controls are transmitted to all the pixels of the image sensor, respectively to a pixel subset of the image sensor, and the image acquisition characteristic is established based on the read signals of all the pixels, respectively, of the pixel subset of the image sensor.
7. The method according to claim 6 , wherein the pixel subset comprises pixels uniformly distributed on the sensor surface.
8. The method according to claim 1 , wherein the read controls are called in a sequential manner.
9. The method using the servoing method of claim 1 , wherein the sensor pixels are read when the image acquisition characteristic corresponds to a preset image acquisition characteristic, and an image is formed based on a read signal obtained during the reading.
10. A radiography device comprising:
an X-ray source ( 806 ) and a MOS-type image sensor ( 810 ) with pixels provided respectively with separate read and refreshment controls;
a sequencer to apply to the read controls a series of call signals, distributed over a radiological exposure period;
a computer ( 812 ) receiving the read signals supplied by the pixels in response to the call signals, to establish an image acquisition characteristic and to compare the acquisition characteristic with a preset acquisition characteristic; and
means ( 817 ) of interrupting the radiological exposure, controlled by the computer, to interrupt the exposure when the acquisition characteristic corresponds to the preset image acquisition characteristic.
11. The device according to claim 10 , also comprising image reproduction means ( 814 ) to supply an image based on the read signals supplied by the pixels.