Method to improve the time resolution of digital silicon photomultipliers

Patent metadata

Field	Value
Publication number	US-9405024-B2
Application number	US-201414339489-A
Country	US
Kind code	B2
Filing date	Jul 24, 2014
Priority date	May 28, 2009
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A radiation detector module for use in a time-of-flight positron emission tomography (TOF-PET) scanner generates a trigger signal indicative of a detected radiation event. A timing circuit including a first time-to-digital converter (TDC) and a second TDC is configured to output a corrected timestamp for the detected radiation event based on a first timestamp determined by the first TDC and a second timestamp determined by the second TDC. The first TDC is synchronized to a first reference clock signal and the second TDC is synchronized to a second reference clock signal, the first and second reference clock signals being asynchronous.

First claim

Having thus described the preferred embodiments, the invention is now claimed to be:

1. A method for associating a time index to a detected event, including:
using a first time-to-digital converter (TDC) to associate time indices to detected events;
if a detected event occurs during a metastable phase of the first TDC, using at least a second TDC to associate a time index to the detected event; and
providing the time indices to detector circuitry.

2. The method according to claim 1 , wherein the metastable phases of the first and second TDCs are non-synchronous.

3. The method according to claim 1 , wherein one of the first and second TDCs has a higher temporal resolution than the other TDC.

4. The method according to claim 1 , wherein the second TDC has a metastable state, the metastable states of the first and second TDCs being temporally offset.

5. The method according to claim 1 , wherein the second TDC has a metastable state, the metastable states of the first and second TDCs being non-concurrent.

6. The method according to claim 1 , further including:
with the first TDC, outputting a first reference clock signal.

7. The method according to claim 6 , further including:
with the second TDC, outputting a second reference clock signal.

8. The method according to claim 7 , wherein the first and second reference clock signals transition between high and low states, the transitions of the first and second clock signals being non-synchronous.

9. The method according to claim 8 , wherein the time indices are provided based on the transitions.

10. The method according to claim 1 , further including:
outputting a first time stamp based on the time indices associated to the detected events by the first TDC;
outputting a second time stamp based on the time indices associated to the detected events by the second TDC;
generating a corrected time stamp based on at least one of the first and second time stamps.

11. The method according to claim 10 , wherein the corrected time stamp is based on the earliest of the first and second time stamps.

12. The method according to claim 1 , further including:
with the detector circuitry, generating a time stamp for the detected event based on the time indices associated with the detected events detected by the first and second TDCs.

13. A method of associated a time index to a detected event, comprising:
with a first TDC which has metastable phases, associating a first time index with the detected event;
with a second TDC which has metastable phases, associating a second time index with the detected event, the metastable phases of the first and second TDCs being non-synchronous.

14. The method according to claim 13 , further including:
with a circuit, generating a time stamp for the detected event based on the first and second time indices.

15. An apparatus for associating a time index to a detected event comprising:
a first TDC configured to associate a first time index to the detected event;
a second TDC configured to associate a second time index with the detected event if the detected event occurs during a metastable state of the first TDC; and
a circuit configured to receive the first and second time indices.

16. The apparatus according to claim 15 , wherein the first and second TDCs are configured to have non-synchronous metastable states.

17. The apparatus according to claim 16 , wherein the circuit is configured to generate a time stamp for the detected event based on the first and second time indices.

18. The apparatus according to claim 17 , wherein the circuit is configured to generate the time stamp based on the earlier of the time indices.

19. The apparatus according to claim 15 , wherein the first TDC is configured to generate a first reference clock signal and the second TDC is configured to generate a second reference clock signal, the first and second reference clock signals being temporally offset.

20. The apparatus according to claim 15 , wherein
the first TDC is configured to generate a first reference clock signal that alternately transitions between a high state and a low state;
the second TDC is configured to generate a second reference clock signal that alternately transitions between a high state and a low state; and
the transitions of the first and second clock signals are temporally displaced.

Assignees

• Frach Thomas
• Prescher Gordian
• Koninklijke Philips Nv

Inventors

• Frach Thomas
• Prescher Gordian

Classifications

• H03M1/0827

  of electromagnetic or electrostatic field noise, e.g. preventing crosstalk by shielding or optical isolation · CPC title

• H03K5/22

  Circuits having more than one input and one output for comparing pulses or pulse trains with each other according to input signal characteristics, e.g. slope, integral (indicating phase difference of two cyclic pulse trains G01R25/00) · CPC title

• A61B6/037

  Emission tomography · CPC title

• G01T1/249

  specially adapted for use in SPECT or PET (SPECT imaging G01T1/1642; PET imaging G01T1/2985; detecting prohibited goods, e.g. weapons, explosives, hazardous substances, contraband or smuggled objects G01V5/20) · CPC title

• G01T1/2985 Primary

  In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); (using external radiation sources A61B6/02) · CPC title