High flux photon counting detector electronics

Patent metadata

Field	Value
Publication number	US-9535167-B2
Application number	US-201314387950-A
Country	US
Kind code	B2
Filing date	Mar 8, 2013
Priority date	Mar 27, 2012
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

An imaging system ( 100 ) includes a radiation source ( 108 ) that emits radiation that traverses an examination region, a paralyzable photon counting detector pixel ( 110 ) that detects photons traversing the examination region and arriving at an input photon rate and that generates a signal indicative thereof, high flux electronics ( 122 ) that produce a total time over threshold value each integration period based on the signal, a reconstruction parameter identifier ( 124 ) that estimates the input photon rate based on the total time over threshold value and identifies a reconstruction parameter based on the estimate, and a reconstructor ( 130 ) that reconstructs the signal based on the identified reconstruction parameter.

First claim

The invention claimed is:

1. An imaging system, comprising:
a radiation source that emits radiation that traverses an examination region;
a paralyzable photon counting detector that detects photons traversing the examination region and arriving at an input photon rate and that generates a signal indicative thereof;
high flux electronics that produce a total time over threshold value each integration period based on the signal;
a reconstruction parameter identifier that estimates the input photon rate based on the total time over threshold value and identifies a reconstruction parameter based on the estimate; and
a reconstructor that reconstructs the signal based on the identified reconstruction parameter.

2. The imaging system of claim 1 , where the reconstruction parameter identifier estimates whether the input photon rate is low or high and identifies the reconstruction parameter based thereon.

3. The imaging system of claim 1 , further comprising:
a shaper that processes the signal and produces a pulse having a height indicative of the signal;
a comparator that compares an amplitude of the pulse with a threshold and generates an output that indicates whether the amplitude exceeds the threshold; and
a counter that counts a number of times the amplitude rises above the threshold each integration period and produces a corresponding count value;
wherein the high flux electronics produce the total time over threshold value based on the output of the comparator;
wherein the reconstruction parameter identifier estimates whether the input photon rate is low or high based on the total time over threshold value and selects one of the count value, the total time over threshold value or a combination thereof.

4. The imaging system of claim 3 , wherein the reconstructor reconstructs the signal data based on the selected one of the count value, the total time over threshold value or a combination thereof.

5. The imaging system of claim 4 , wherein the total time over threshold value indicates a total amount of time the amplitude is above the threshold an integration period.

6. The imaging system of claim 3 , the high flux electronics, comprising:
a switched current source that generates a fixed current when switched on and no current when switched off, wherein the output of the comparator switches the switched current source; and
an integrator that integrates the fixed current and determines a total charge each integration period,
wherein the reconstruction parameter identifier estimates whether the input photon rate is low or high based on the total charge.

7. The imaging system of claim 6 , further comprising:
an A/D converter that converts the integrated charge to a digital signal, wherein the reconstruction parameter identifier estimates whether the input photon rate is low or high based on the digital signal.

8. The imaging system of claim 3 , the high flux electronics, comprising:
a high frequency digital clock generator that produces a high frequency digital clock; logic that gates the high frequency digital clock; and
a counter that counts pulses of the gated clock,
wherein the reconstruction parameter identifier estimates whether the input photon rate is low or high based on the counted pulses.

9. The imaging system of claim 8 , wherein the output of the comparator controls the gating of the high frequency digital clock and gates the logic in response to the output indicating the amplitude is above the threshold.

10. The imaging system of claim 1 , wherein the reconstruction parameter identifier estimates the input photon rate and identifies the reconstruction parameter based on a pulse pile up model, which models a behavior of the counter and the high flux electronics.

11. A method, comprising:
receiving, via an output of a paralyzable photon counting detector pixel, a signal indicative of photons detected during an integration interval;
estimating an input photon rate of the photons based on a total time over threshold value;
identifying a reconstruction parameter based on the estimate; and
reconstructing the signal based on the identified reconstruction parameter.

12. The method of claim 11 , where the reconstruction parameter identifier estimates whether the input photon rate is low or high and identifies the reconstruction parameter based thereon.

13. The method of claim 11 , further comprising:
shaping the signal to produce a pulse having a height indicative of the signal;
comparing an amplitude of the pulse with a threshold and generating an output that indicates whether the amplitude exceeds the threshold;
counting a number of times the amplitude rises above the threshold each integration period and producing a corresponding count value; and
processing the output of the comparator and producing the total time over threshold value each integration period;
wherein the input photon rate is estimated as low or high based on the total time over threshold value.

14. The method of claim 13 , further comprising:
reconstructing the signal data based on one of the count value, the total time over threshold value or a combination thereof.

15. The method of claim 14 , wherein the total time over threshold value indicates a total amount of time the amplitude is above the threshold an integration period.

16. The method of claim 13 , further comprising:
switching a switched current source, which generates a fixed current, on and off with the output of the comparator;
integrating the generated fixed current, thereby determining a total charge for an integration interval; and
estimating whether the input photon rate is low or high based on the total charge.

17. The method of claim 16 , further comprising:
converting the total charge to a digital signal; and
estimating whether the input photon rate is low or high based on the digital signal.

18. The method of claim 13 , further comprising:
producing a high frequency digital clock;
gating the high frequency digital clock using with the output of the comparator;
counting pulses of the gated clock; and
estimating whether the input photon rate is low or high based on the counted pulses.

19. The method of claim 11 , further comprising:
identifying the reconstruction parameter based on a pulse pile up model.

20. A method, comprising:
receiving, via high flux electronics, an output of a comparator for a photon counting detector for an integration interval;
determining, via the high flux electronics, a total amount of time the output of the comparator exceeds a threshold;
using, via a reconstruction parameter identifier, the determined total amount of time to estimate whether the input photon rate is low or high; and
determining, via the reconstruction parameter identifier, a reconstructor parameter based on the estimation.

Assignees

• Koninklijke Philips Nv

Inventors

• Proksa Roland
• Steadman Booker Roger

Classifications

• G01T1/171 Primary

  Compensation of dead-time counting losses · CPC title

• G01T1/1606

  with other specified detectors not provided for in the other subgroups of G01T1/16 · CPC title