Pulse-width modulation for a photon scanning apparatus

Patent metadata

Field	Value
Publication number	US-10983071-B2
Application number	US-201816305446-A
Country	US
Kind code	B2
Filing date	May 2, 2018
Priority date	May 4, 2017
Publication date	Apr 20, 2021
Grant date	Apr 20, 2021

Abstract

The present invention relates to a photon scanning apparatus comprising a photon source ( 2 ) to emit a photon beam ( 4 ), a photon detector ( 6 ) to detect photons emitted from the photon source ( 2 ). The photon source ( 2 ) is adapted to emit the photon beam ( 4 ) in accordance with a predetermined pulse width modulation scheme at a predetermined flux rate, wherein the pulse width modulation scheme defines pulse widths of the photon beam ( 4 ) for respective positions of the photon source ( 2 ) and the photon detector around a central axis (R) and an object to be scanned. The photon detector ( 6 ) is adapted to start detecting photons with a delay relative to the photon source starting to emit photons and to finish detecting photons prior to the photon source stopping to emit photons. The photon scanning apparatus thus only has to be calibrated for the predetermined flux rate.

First claim

The invention claimed is:

1. A photon scanning apparatus, comprising:
a photon source to emit a photon beam; and
a photon detector positioned in the propagation direction of the photon beam to detect photons emitted from the photon source, wherein the photon source and the photon detector are commonly rotatable around a central axis;
wherein the photon source is configured to emit the photon beam in accordance with a predetermined pulse width modulation scheme at a predetermined flux rate, wherein the pulse width modulation scheme defines pulse widths of the photon beam for respective positions of the photon source and the photon detector around and along the central axis and an object to be scanned, and
wherein the photon detector is configured to start detecting photons for a time period corresponding to the predetermined pulse width with a delay relative to the photon source starting to emit photons and to finish detecting photons prior to the photon source stopping to emit photons.

2. The photon scanning apparatus according to claim 1 , wherein the photon source is configured to issue a command indicative of an emission period corresponding to a predetermined pulse width to the photon detector upon starting to emit the photon beam, and the photon detector is configured to start counting photons upon a predetermined delay after receipt of the command.

3. The photon scanning apparatus according to claim 1 , wherein the photon source is configured to issue a command indicative of an emission time corresponding to a predetermined pulse width to the photon detector with a predetermined delay after having started to emit photons, and the photon detector is configured to start counting photons upon receipt of the command for a time period that is shorter than the predetermined pulse width by a predetermined amount.

4. The photon scanning apparatus according to claim 1 , further comprising a control unit to determine a rotational position of the photon source in accordance with the pulse width modulation scheme and to issue a control command to the photon source and the photon detector indicative of respective operation periods corresponding to a particular pulse width, wherein the photon source is configured to start emitting photons upon receipt of the control command for an emission period corresponding to the particular pulse width, and the photon detector is configured to start counting photons upon a predetermined delay after receipt of the control command for a detection period that ends with the emission period.

5. The photon scanning apparatus according to claim 1 , further comprising a control unit to determine a rotational position of the photon source in accordance with the pulse width modulation scheme and to issue a first control command to the photon source, wherein the photon source is configured to start emitting the photon beam upon receipt of the first control command for a predetermined first period of time, and to issue a second control command to the photon detector, wherein the photon detector is configured to start counting photons upon receipt of the second control command for a predetermined second period of time that ends a predetermined amount before the first period of time.

6. The photon scanning apparatus according to claim 1 , wherein the photon scanning apparatus is a spectral computed tomography scanning apparatus.

7. A method for operating a photon scanning apparatus at a predetermined flux rate comprising a photon source to emit a photon beam according to a predetermined pulse width modulation scheme and a photon detector positioned in the propagation direction of the photon beam to detect photons emitted from the photon source, wherein the photon source and the photon detector are commonly rotatable around a central axis, the method comprising:
scanning the object using a pulse width according to the pulse width modulation, wherein the photon detector starts detecting photons for a time period corresponding to the predetermined pulse width with a predetermined delay relative to the photon source starting to emit photons, and wherein the photon detector finishes detecting photons prior to the photon source stopping to emit photons.

8. A non-transitory computer-readable medium having executable instructions stored thereon which, when executed by at least one processor, cause the at least one processor to perform a method for operating a photon scanning apparatus at a predetermined flux rate comprising a photon source to emit a photon beam according to a predetermined pulse width modulation scheme and a photon detector positioned in the propagation direction of the photon beam to detect photons emitted from the photon source, wherein the photon source and the photon detector are commonly rotatable around a central axis, the method comprising:
scanning the object using a pulse width according to the pulse width modulation, wherein the photon detector starts detecting photons for a time period corresponding to the predetermined pulse width with a predetermined delay relative to the photon source starting to emit photons, and wherein the photon detector finishes detecting photons prior to the photon source stopping to emit photons.

Assignees

• Koninklijke Philips Nv

Inventors

• Daerr Heiner
• Proksa Roland
• Bergner Frank

Classifications

• G01N23/046 Primary

  using tomography, e.g. computed tomography [CT] · CPC title

• G01T7/005

  calibration techniques (stabilization of spectrometer G01T1/40) · CPC title

• G01T1/02

  Dosimeters (G01T1/15 takes precedence) · CPC title

• A61B6/032

  Transmission computed tomography [CT] · CPC title

• A61B6/582

  Calibration · CPC title