Rise/fall time control for X-ray pulses

• US 8,755,491 B2
• Filed: 03/29/2010
• Issued: 06/17/2014
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: Varex Imaging Corporation
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Rosevear, Thomas William, Khutoryansky, Oscar, Maltsev, Yevgeny
• Primary Examiner(s): Kiknadze, Irakli
• Application Number:
  US13/259,943
• Publication Number:
  US 20120170717A1
• Time in Patent Office: 1,541 Days
• Field of Search: 378/101, 378/103, 378/102, 378/108, 378110-114
• US Class Current: 378/103
• CPC Class Codes: A61B 6/56 Details of data transmission or power supply, e.g. use of slip rings
• CPC Class Codes: H05G 1/12 with dc or rectified single-phase ac or double-phase
• CPC Class Codes: H05G 1/24 Obtaining pulses by using energy storage devices

Abstract

A method for generating a fast rise-time X-ray pulse includes the steps of providing an n-phase x-ray generator, the x-ray generator including an n-phase transformer having at least one primary winding and at least one secondary winding per phase, and providing n sections of rectifiers, each rectifier having at least a fast pulse rise-time mode and a n-phase ripple flat-top mode. According to the method, at least a first capacitor is charged in each of the n sections of rectifiers at a ripple of less than n-phases to create a fast leading edge of the fast rise-time pulse, and at least a second capacitor is charged in each of the n sections or rectifiers at an n-phase ripple to create a substantially flat-top of the fast rise-time pulse.

Claims

1. An X-ray generator for generating a fast rise-time pulse, said generator comprising:

a n-phase poly-phase transformer having at least one primary winding and at least one secondary winding per phase;

n rectifier circuits, each one of said n rectifier circuits being electrically coupled to each of said at least one secondary winding per phase, each of said n rectifier circuits comprising at least a first capacitor electrically coupled to at least a first rectifier, said first rectifier electrically disposed between said at least one secondary winding and said first capacitor and configured to provide a fast rise time of a leading edge of a fast rise-time pulse, and at least a second capacitor electrically coupled to at least a second rectifier, said second rectifier being electrically disposed between said at least one secondary winding and said second capacitor configured to provide a filtered n-phase pulse flat-top; and

at least n active control switches, each of said active control switches being electrically coupled to at least one of said primary winding and configured to set a selected one of rectifier mode;

     1) a fast pulse rise-time mode and

     2) a flat-top low ripple mode, and

wherein each of said first capacitors is charged by a rectified phase ripple of less than n at or before a leading edge of said fast rise-time pulse, and each of said second capacitors is configured to operate with an n-phase ripple to provide a substantially flat top of said fast rise-time pulse.

2. The x-ray generator according to claim 1, wherein each of said first capacitor and said second capacitor are pre-charged before the leading edge of said fast rise-time pulse.

3. The x-ray generator according to claim 1, wherein a peak pulse amplitude of said fast rise-time pulse is generated by a series combination of a plurality of rectified voltages, each one of said plurality of rectified voltages being output from each of said n-rectifiers.

4. A method for generating a fast rise-time X-ray pulse, said method comprising:

providing an n-phase x-ray generator, said generator including an n-phase transformer having at least one primary winding and at least one secondary winding per phase;

providing n sections of rectifiers, each rectifier having at least a fast pulse rise-time mode and a n-phase ripple flat-top mode;

charging at least a first capacitor in each of said n sections of rectifiers at a ripple of less than n-phases to create a fast leading edge of said fast rise-time X-ray pulse; and

charging at least a second capacitor in each of said n sections at an n-phase ripple to create a substantially flat-top of said fast rise-time X-ray pulse.

5. The method according to claim 4, further comprising pre-charging said first capacitor prior to the act of charging said first capacitor.

6. The method according to claim 4, further comprising pre-charging said second capacitor prior to the act of charging the first capacitor.

7. The method according to claim 4, further comprising discharging said first capacitor to create a fast fall time of a falling edge of said fast rise-time pulse prior to said act of charging at least the second capacitor.

8. The method according to claim 4, further comprising discharging said second capacitor prior to said act of charging at least the second capacitor.