Direct attach radiation detector structures including pixelated sensors and read-out circuitry having varying pitch
Direct attach radiation detector structures include an application specific integrated circuit (ASIC) including an array of unit cells including signal processing channel circuitry and at least one radiation sensor including an array of pixel detectors located over a front surface of the ASIC. In various embodiments, an ASIC having a fixed layout of unit cells may accommodate different radiation sensors having varying layouts of pixel detectors. In some embodiments, a redistribution layer on the front surface of the ASIC may route detection signals from pixel detectors to the corresponding unit cells. Alternatively, or in addition, a subset of the unit cells of the ASIC may be active unit cells that are electrically coupled to a pixel detector. The remaining unit cells may be inactive unit cells that may be powered down.
1 . A detector structure, comprising:
at least one radiation sensor comprising an array of pixel detectors;
an application specific integrated circuit (ASIC), comprising:
an array of unit cells, each unit cell comprising signal processing channel circuitry and a contact region on a front surface of the ASIC, wherein the contact region comprises an input node to the signal processing circuitry of the unit cell; and
a redistribution layer located on the front surface of the ASIC, the redistribution layer comprising at least one bonding region laterally displaced from, and electrically connected to, a contact region of a unit cell; and
a plurality of bonding material portions, each of the bonding material portions extending between a respective pixel detector of the array of pixel detectors and the front surface of the ASIC, wherein at least a portion of the bonding material portions contact a bonding region of the redistribution layer;
wherein:
the array of unit cells has an identical pitch between adjacent unit cells in the array unit cells,
the pixel detectors of the radiation sensor have an identical pitch between adjacent pixel detectors, wherein the pitch between adjacent pixel detectors is greater than the pitch between adjacent unit cells, and
a ratio between the pitch between adjacent pixel detectors and the pitch between adjacent unit cells is an integer value.
2 . An X-ray imaging system, comprising:
a radiation source configured to emit X-rays; and
a detector array including a plurality of detector structures of claim 1 that form a continuous detector surface and that are configured to receive the X-rays from the radiation source through an intervening space configured to contain an object therein.
3 . The X-ray imaging system of claim 2 , wherein the X-ray imaging system comprises a photon-counting computerized tomography (PCCT) imaging system comprising an image reconstruction system including a computer configured to run an automated image reconstruction algorithm on event detection signals generated by the detector modules of the detector array.
4 . A detector structure, comprising:
at least one radiation sensor comprising an array of pixel detectors;
an application specific integrated circuit (ASIC), comprising:
an array of unit cells, each unit cell comprising signal processing channel circuitry and a contact region on a front surface of the ASIC, wherein the contact region comprises an input node to the signal processing circuitry of the unit cell; and
a redistribution layer located on the front surface of the ASIC, the redistribution layer comprising at least one bonding region laterally displaced from, and electrically connected to, a contact region of a unit cell; and
a plurality of bonding material portions, each of the bonding material portions extending between a respective pixel detector of the array of pixel detectors and the front surface of the ASIC, wherein at least a portion of the bonding material portions contact a bonding region of the redistribution layer;
wherein:
the array of unit cells has an identical pitch between adjacent unit cells in the array unit cells,
the pixel detectors of the radiation sensor have an identical pitch between adjacent pixel detectors, wherein the pitch between adjacent pixel detectors is greater than the pitch between adjacent unit cells, and
a ratio between the pitch between adjacent pixel detectors and the pitch between adjacent unit cells is a non-integer value.
5 . A detector structure, comprising:
at least one radiation sensor comprising an array of pixel detectors having a first pitch between adjacent pixel detectors; and
an application specific integrated circuit (ASIC) comprising an array of unit cells having a second pitch between adjacent pixel detectors, each unit cell comprising signal processing channel circuitry and a contact region on a front surface of the ASIC that comprises an input node to the signal processing circuitry of the unit cell,
wherein:
the first pitch is greater than the second pitch,
the at least one radiation sensor is mounted over the front surface of the ASIC such that each pixel detector is electrically coupled to a contact region of a respective unit cell of the ASIC,
a first plurality of the unit cells of the ASIC comprise active unit cells that include a contact region that is electrically coupled to a pixel detector of the at least one radiation sensor, and
a second plurality of the unit cells of the ASIC comprise inactive unit cells that are not electrically coupled to a pixel detector of the at least one unit sensor.
6 . The detector structure of claim 5 , wherein the inactive unit cells of the ASIC do not receive electrical power during operation of the detector structure.
7 . The detector structure of claim 5 , further comprising a plurality of bonding material portions, each of the bonding material portions extending between a respective pixel detector of the at least one radiation sensor and the front surface of the ASIC.
8 . The detector structure of claim 7 , wherein:
each of the bonding material portions contacts a contact region of an active unit cell of the ASIC;
the ASIC comprises at least one through-substrate via extending through the ASIC; and the at least one radiation sensor is bonded directly to the ASIC via the plurality of bonding material portions without an interposer located between the at least one radiation sensor and the ASIC.
9 . The detector structure of claim 7 , wherein at least a portion of the bonding material portions contact a bonding region of a redistribution layer located on the front surface of ASIC, wherein each of the bonding regions is laterally displaced from, and electrically coupled to, a contact region of an active unit cell of the ASIC.
10 . The detector structure of claim 5 , wherein the signal processing channel circuitry in each of the unit cells comprises an amplifier coupled to the contact region of the unit cell, a shaper circuit block coupled to the amplifier, a discrimination circuit block coupled to the shaper circuit block, and a counter circuit block coupled to the shaper circuit block.
11 . The detector structure of claim 10 , wherein the amplifier comprises a charge sensitive amplifier (CSA), the signal processing circuitry further comprises a baseline restoration (BLR) circuit block, and the discrimination circuit block comprises a plurality of comparator circuits coupled to a respective counter circuit block and configured to sort photon interaction events into different energy bins.
12 . A method of opening the detector structure of claim 5 , comprising:
providing X-rays from a radiation source through an intervening space containing an object therein to the at least one radiation sensor;
providing power to the active unit cells during the step of providing X-rays to detect a signal from the at least one radiation sensor; and
providing no power to the inactive unit cells during the step of providing X-rays.