Radiation sensor with x-ray detection

An intraoral radiological image sensor using MOS technology comprising a matrix of rows and columns of photosensitive pixels each comprising a photodiode and a circuit with transistors allowing the charges generated by light in the pixel to be collected and converted to voltage;

• and
• for each column of pixels, a column conductor common to all of the pixels of the column, the column conductor being connected to a respective readout circuit for the column;
• a row-addressing circuit for addressing the pixels of a selected row and transferring, to the column conductors, useful signals arising from the pixels of the selected row and representing the illumination of these pixels;
• and
• the sensor including, in the middle of the matrix and in place of a central column or a central row of pixels, a series of detection photodiodes which are all electrically connected on one side to a reference potential and on the other side to one and the same detection conductor extending along the series of photodiodes, this detection conductor being connected to a detection circuit delivering a signal for triggering the capture of an image when the detected current or the variation in this current exceeds a threshold showing that an X-ray flash has been initiated.