X-ray detector and method for measuring energy of individual x-ray photons for improved imaging of subjects using reduced dose

An x-ray detector for detecting x-rays to provide a measure of energy of individual x-ray photons from a source which emits x-ray photons having a plurality of energy levels, comprising:

• a detection mechanism which generates a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels in response to x-ray photons impacting the individual pixels;
• a readout circuit connected to the detection mechanism which reads out the response of each pixel at a readout rate defined by a period, wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible;
• a plurality of register readout cells constructed as a shift register and wherein each register readout cell is connected to a corresponding pixel in the detection mechanism;
• and
• a readout controller connected to transfer the response in each pixel of the detection mechanism into each register readout cell corresponding to the pixel at the readout rate, wherein the readout controller transfers the response from a portion of the pixels of the detection mechanism to the corresponding register readout cells in parallel and wherein the readout controller shifts responses from the register readout cells serially through the shift register and an output register cell.

A method for detecting x-rays to provide a measure of energy of individual x-ray photons from a source which emits x-ray photons having a plurality of energy levels, comprising the steps of:

• generating a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels of a detection mechanism in response to x-ray photons impacting the individual pixels;
• reading out the response of each pixel at a rate defined by a period wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible;
• weighting each response read out of each pixel to provide a weighted response for each pixel;
• and
• accumulating, for each pixel, a sum of the weighted responses of the pixel.

An x-ray detector for detecting x-rays to provide a measure of energy of individual x-ray photons from a source which emits x-ray photons having a plurality of energy levels, comprising:

• means for generating a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels in response to x-ray photons impacting the individual pixels;
• means for reading out the response of each pixel at a rate defined by a period wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible;
• means for weighting each response read out of each pixel to provide a weighted response for each pixel;
• and
• means for accumulating, for each pixel, a sum of the weighted responses of the pixel.

An apparatus for obtaining x-ray attenuation information of a subject, comprising:

• an x-ray source which directs x-ray photons towards a subject;
• a detection mechanism arranged to detect x-ray photons transmitted through the subject and which generates a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels in response to x-ray photons impacting the individual pixels;
• a readout circuit connected to the detection mechanism which reads out the response of each pixel at a readout rate defined by a period, wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible;
• a weighting circuit having an input connected to receive the responses of each pixel from the readout circuit and an output providing a weighted response for each received response;
• and
• a summation circuit connected to the output of the weighting circuit which accumulates, for each pixel, a sum of the weighted responses of the pixel.

A method for obtaining x-ray attenuation information of a subject, the method comprising the steps of:

• directing x-ray photons towards the subject;
• generating a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels of a detection mechanism in response to x-ray photons impacting the individual pixels;
• reading out the response of each pixel at a rate defined by a period wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible
• weighting each response read out of each pixel to provide a weighted response for each pixel;
• accumulating, for each pixel, a sum of the weighted responses of the pixel.

An apparatus for obtaining x-ray attenuation information of a subject, comprising:

• means for directing x-ray photons towards the subject;
• means for generating a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels in response to x-ray photons impacting the individual pixels;
• means for reading out the response of each pixel at a rate defined by a period wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible;
• means for weighting each response read out of each pixel to provide a weighted response for each pixel;
• and
• means for accumulating, for each pixel, a sum of the weighted responses of the pixel.

An apparatus for obtaining x-ray attenuation information of a subject, comprising:

• a controllable x-ray source for directing x-ray photons having an energy greater than 10 keV towards a subject, wherein the x-ray source provides an x-ray photon flux of more than several hundred x-ray photons per square millimeter per millisecond;
• a detection mechanism arranged to detect x-ray photons transmitted through the subject and which generates a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels in response to x-ray photons impacting the individual pixels;
• and
• a readout circuit connected to the detection mechanism which reads out the response of each pixel at a readout rate defined by a period, wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible.

A method for obtaining x-ray attenuation information of a subject, the method comprising the steps of:

• controllably directing x-ray photons having an energy of greater than 10 KeV towards the subject at an x-ray photon flux of more than several hundred x-ray photons per square millimeter per millisecond;
• generating a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels of a detection mechanism in response to x-ray photons impacting the individual pixels;
• and
• reading out the response of each pixel at a rate defined by a period wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible.

An apparatus for obtaining x-ray attenuation information of a subject, comprising:

• means for controllably directing x-ray photons having an energy of greater than 10 keV towards the subject at an x-ray photon flux of more than several hundred x-ray photons per square millimeter per millisecond;
• means for generating a response to an x-ray photon as a function of the energy of the x-ray photon, wherein the response is generated in each of a plurality of pixels in response to x-ray photons impacting the individual pixels;
• and
• means for reading out the response of each pixel at a rate defined by a period wherein the likelihood of arrival of more than one x-ray photon in one pixel in one period is negligible.

An x-ray detector for detecting x-rays to provide a measure of energy of individual x-ray photons from a controllable x-ray source which emits x-ray photons having a plurality of energy levels, comprising:

• a coupling mechanism which generates a charge to an x-ray photon as a function of the energy of the x-ray photon, wherein the coupling mechanism is divided into picture elements, each picture element having a separably determinable charge and defining a set of pixels;
• a plurality of detector cells, each detector cell connected to a corresponding pixel in the coupling mechanism into which the charge of the corresponding pixel in the coupling mechanism is transferred;
• and
• a readout circuit connected to the plurality of detector cells which reads out the charge of each detector cell at a readout rate defined by a period, wherein the likelihood of arrival of more than one x-ray photon in one pixel of the coupling mechanism in one period is negligible.