Remote control of cathode width voltage

Patent metadata

Field	Value
Publication number	US-12382569-B2
Application number	US-202318484277-A
Country	US
Kind code	B2
Filing date	Oct 10, 2023
Priority date	Oct 10, 2023
Publication date	Aug 5, 2025
Grant date	Aug 5, 2025

Abstract

Methods and systems are provided for controlling an electron beam generated by an X-ray tube assembly including a unipolar cathode with a long cable between driving electronics of the cathode and the X-ray tube. A voltage supplied to a gridding electrode of the cathode is controlled by a multi-stage switching unit including a first control circuit and a second control circuit. A bias voltage for switching the cathode on is generated by a high precision voltage source of the second control circuit, and a gridding voltage for switching the cathode off is generated by voltage sources of the first control circuit. A time taken to transition between the gridding voltage and the bias voltage is advantageously reduced by decreasing the supplied voltage to a common voltage (e.g., 0 V) in a first step, and then increasing the supplied voltage to the bias voltage or the gridding voltage in a second step.

First claim

The invention claimed is:

1. A method for an interventional imaging system, the method comprising:
applying a voltage to a gridding electrode of a cathode of the interventional imaging system;
controlling a first transition of the voltage from a first, gridding voltage of the interventional imaging system to a second, bias voltage of the interventional imaging system to perform an X-ray exposure using the interventional imaging system, by decreasing the voltage from the first, gridding voltage to a common voltage of the interventional imaging system, and increasing the voltage from the common voltage to the second, bias voltage; and
controlling a second transition of the voltage from the second, bias voltage to the first, gridding voltage to stop performing the X-ray exposure by decreasing the voltage from the second, bias voltage to the common voltage, and increasing the voltage from the common voltage to the first, gridding voltage.

2. The method of claim 1 , wherein the cathode is a unipolar cathode, and both of the first, gridding voltage and the second, bias voltage are negative voltages.

3. The method of claim 2 , wherein driving electronics of the unipolar cathode are connected through a cable with a length greater than 40 meters.

4. The method of claim 1 , wherein the voltage is applied to the gridding electrode via a multi-stage switching unit including a first control circuit and a second, different control circuit, wherein the first, gridding voltage is generated by the first control circuit, and the second, bias voltage is generated by the second control circuit.

5. The method of claim 4 , wherein:
the first, gridding voltage is −8 kV with respect to the common voltage, and the first control circuit includes eight switching units, each switching unit of the eight switching units including a −1 kV voltage source; and
the second, bias voltage is between 0 and −1.2 kV with respect to the common voltage, and the second control circuit includes a high precision voltage source capable of generating up to 1.2 kV with a precision of +/−50V and two switches to bypass or to connect negatively the high precision voltage source to the cathode.

6. The method of claim 5 , wherein each switching unit of the eight switching units includes a capacitor.

7. The method of claim 5 , wherein:
increasing the voltage from the common voltage to the first, gridding voltage further comprises actuating one or more switches of each switching unit of the eight switching units of the first control circuit to a closed position to generate a first voltage of −8 kV, the first voltage a threshold voltage for switching off the cathode; and
increasing the voltage from the common voltage to the second, bias voltage further comprises actuating one or more switches of the second control circuit to generate a second voltage of −1.2 kV with the precision of +/−50V, the second voltage a threshold voltage for switching on the cathode.

8. The method of claim 1 , wherein:
a first total amount of time taken to decrease the voltage from the first, gridding voltage to the common voltage and increase the voltage from the common voltage to the second, bias voltage is less than 50 us; and
a second total amount of time taken to decrease the second, bias voltage to the common voltage, and increase the voltage from the common voltage to the first, gridding voltage is less than 50 us.

9. An interventional imaging system, comprising:
an X-ray source including a cathode;
a plurality of voltage sources configured to supply a voltage to a gridding electrode of the cathode;
a first control circuit configured to generate a first, gridding voltage to the gridding electrode;
a second control circuit configured to generate a second, bias voltage to the gridding electrode; and
a control system operably connected to the X-ray source and configured to:
in response to receiving an instruction to switch the cathode of the X-ray source on, decrease the voltage applied to the gridding electrode from the first, gridding voltage to a common voltage of the interventional imaging system in a first step using the first control circuit, and increase the voltage from the common voltage to the second, bias voltage in a second step using the second control circuit; and
in response to receiving an instruction to switch the cathode off, decrease the voltage from the second, bias voltage to the common voltage in a first step using the second control circuit; and increase the voltage from the common voltage to the first, gridding voltage in a second step using the first control circuit.

10. The interventional imaging system of claim 9 , wherein the cathode is a unipolar cathode, and both of the first, gridding voltage and the second, bias voltage are negative voltages with respect to the common voltage.

11. The interventional imaging system of claim 10 , wherein driving electronics of the unipolar cathode are connected through a cable with a length greater than 40 meters.

12. The interventional imaging system of claim 9 , wherein the first control circuit comprises eight voltage modules arranged in a cascading multi-stage architecture, each voltage module including a −1 kV voltage source and one or more switches, the first control circuit configurable to supply up to a total voltage equal to −8 kV with respect to the common voltage.

13. The interventional imaging system of claim 9 , wherein the second control circuit comprises a variable high precision voltage source capable of delivering up to −1.2 kV with respect to the common voltage.

14. The interventional imaging system of claim 9 , wherein a total voltage supplied by the first control circuit and the second control circuit is a gridding voltage of −8 kV with respect to the common voltage.

15. The interventional imaging system of claim 9 , wherein a first total amount of time taken to decrease the voltage from the first, gridding voltage to the common voltage and increase the voltage from the common voltage to the second, bias voltage is less than 50 us; and a second total amount of time taken to decrease the second, bias voltage to the common voltage, and increase the voltage from the common voltage to the first, gridding voltage is less than 50 us.

16. The interventional imaging system of claim 9 , wherein:
in a first condition when the cathode is switched on, the second, bias voltage is applied to the gridding electrode by the second control circuit, and no voltage is applied to the gridding electrode by the first control circuit; and

in a second condition when the cathode is switched off, the first gridding voltage is applied to the gridding electrode by the first control circuit, and no voltage is applied to the gridding electrode by the second control circuit.

17. A method for an interventional imaging system, the method comprising:
in response to receiving an instruction to switch on a cathode of the interventional imaging system:
decreasing a voltage supplied to a gridding electrode of the cathode from a first, gridding voltage of the interventional imaging system to a common voltage of the interventional imaging system; and
increasing the voltage from the common voltage to a second, bias voltage of the interventional imaging system; and

in response to receiving an instruction to switch the cathode off:
decreasing the voltage from the second, bias voltage to the common voltage; and
increasing the voltage from the common voltage to the first, gridding voltage;
wherein:
a first control circuit of a multi-stage switching unit of the interventional imaging s

Assignees

• Ge Prec Healthcare Llc

Inventors

• Louvrier Yannick
• Nicolle Julien
• Caiafa Antonio
• Cabrol Loic

Classifications

• H05G1/58

  Switching arrangements for changing-over from one mode of operation to another, e.g. from radioscopy to radiography, from radioscopy to irradiation {or from one tube voltage to another} · CPC title

• H05G1/56

  Switching-on; Switching-off · CPC title

• H05G1/085 Primary

  Circuit arrangements particularly adapted for X-ray tubes having a control grid · CPC title