Patient support device and method of operation

• US 7,784,127 B2
• Filed: 09/04/2008
• Issued: 08/31/2010
• Est. Priority Date: 09/04/2007
• Status: Active Grant

• Current Assignee: Accuray Incorporated
• Original Assignee: TomoTherapy Incorporated (Accuray Incorporated)
• Inventors: Reitz, Graham T., Brunker, Bradley J., Harper, Brent, Kuro, Serge Nukhim
• Primary Examiner(s): Cuomo; Peter M
• Assistant Examiner(s): Wilson; Brittany M
• Application Number:
  US12/204,628
• Publication Number:
  US 20090056021A1
• Time in Patent Office: 726 Days
• Field of Search: 560/1, 561/1, 561/6, 378/209, 378/111, 378/65, 378/93, 318375-381, 318371-372
• US Class Current: 5/601
• CPC Class Codes: A61B 6/0487 Motor-assisted positioning
• CPC Class Codes: A61B 6/465 adapted to display user selection data, e.g. graphical user interface, icons or menus
• CPC Class Codes: A61B 6/467 characterised by special input means
• CPC Class Codes: A61B 6/469 for selecting a region of interest [ROI]
• CPC Class Codes: A61B 6/547 involving tracking of position of the device or parts of the device
• CPC Class Codes: A61N 2005/1074 Details of the control system, e.g. user interfaces
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: H02P 31/00 Arrangements for regulating or controlling electric motors not provided for in groups H02P1/00 - H02P5/00, H02P7/00 or H02P21/00 - H02P29/00

Abstract

A patient support device of a radiation therapy treatment system includes an electromechanical motor and control system for raising and lowering the support device in the Z direction. The control system utilizes regenerative braking concepts, converting the motor into a generator as the support device is lowered such that no matter the load, the support device will be lowered at a constant speed. The control system also allows for lowering of the support device in the powered off situation (i.e., when there is no power to the support device).

Claims

1. A patient support device comprising:

a base;

a table assembly supported by the base and configured to support a patient;

an actuator assembly electrically coupled to and operable to control motion of the table assembly, the actuator assembly including a motor and a brake;

a controller electrically coupled to the actuator assembly, the controller operable to generate a signal to activate the brake when power to the actuator assembly is interrupted; and

an dynamic brake assembly electrically coupled to the actuator assembly and the controller, the dynamic brake assembly operable upon deactivation of the brake, the dynamic brake assembly including a passive dynamic load module electrically coupled to the motor to increase speed of the motor,

a rectification module electrically coupled to the motor and operable to convert AC voltage to DC voltage when the AC voltage reaches a predetermined value,

a controlled dynamic load module electrically coupled to the passive dynamic load module, and

a switch operable to deactivate the brake and electrically couple the controlled dynamic load module and the actuator assembly to control a braking operation of the motor.

2. The patient support device of claim 1 wherein the motor is operable to control a substantially vertical motion of the table assembly.

3. The patient support device of claim 1 wherein the passive dynamic load module includes a capacitive dynamic load module and a resistive dynamic load module.

4. The patient support device of claim 3 wherein the passive dynamic load module further includes a voltage sensor dynamic load module.

5. The patient support device of claim 4 wherein the voltage sensor dynamic load module is operable to receive the DC voltage on the motor from the rectification module.

6. The patient support device of claim 1 wherein the controlled dynamic load module includes a current sensor dynamic load and a controlled dynamic load.

7. A radiation therapy treatment system comprising:

a patient support device including

a table assembly configured to support a patient,

an actuator assembly electrically connected to the table assembly and operable to control movement of the table assembly, the actuator assembly including a motor and a brake; and

a control system electrically connected to the actuator assembly the control system including a dynamic brake assembly operable upon release of the brake and operable to control a speed of the motor and provide linear motion of the table assembly when power to the actuator assembly is interrupted.

8. A radiation therapy treatment system of claim 7 wherein the dynamic brake assembly includes

a passive dynamic load module electrically coupled to the motor to increase speed of the motor,

a rectification module electrically coupled to the motor and operable to convert AC voltage to DC voltage when the AC voltage reaches a predetermined value,

a controlled dynamic load module electrically coupled to the passive dynamic load module, and

a switch operable to release the brake and electrically couple the controlled dynamic load module and the actuator assembly to control a braking operation of the motor.

9. The radiation therapy treatment system of claim 8 wherein the controlled dynamic load module includes a current sensor dynamic load and a controlled dynamic load.

10. The radiation therapy treatment system of claim 9 wherein the current sensor dynamic load is connected to the motor when a voltage on the current sensor dynamic load is equal to or greater than a reference voltage.