Real-Time Position Monitoring and Adaptive Head Motion Control Method for Frameless Stereotactic Radiosurgery/Radiotherapy

University of Chicago
posted on 08/27/2009

The system measures real-time 6D position information from the patient to control the radiation treatment beam (gating) and to guide an electronically controlled head motion compensation stage during stereotactic radiosurgery (SRS) and radiotherapy (SRT).

Suggested Uses

This system can be used to monitor and compensate for patient motion during stereotactic radiosurgery and radiotherapy.

Advantages

Currently to achieve sub-millimeter precision for intracranial SRS, a head ring is rigidly fixated to the skull to create a fixed reference. This optical system eliminates the need for a head ring, which is rigidly fixated to the patient's skull for conventional SRS/SRT, making the treatment less invasive and time consuming. Due to the continuous sub-mm head position corrections during treatment, the method is typically more accurate than conventional SRS/SRT, where position correction is only performed once at the start of treatment.

Innovation Details

Detailed Description

The system measures real-time 6D optical position feedback for gating the treatment beam and guiding a motor controlled head motion compensation stage. It consists of a central control computer, an optical patient motion tracking system, and a motion compensation stage. The infrared tracking system is used to monitor four optical reflective markers with an accuracy of -0.25 mm. Measurements are calculated on six degrees of freedom (xyz + rotations). A styrofoam head cast is custom-built for patient support and attached to a linear accelerator (LINAC) couch mount that can be microadjusted in 3D. If the position of the patient deviates beyond a preset motion tolerance, the treatment beam is automatically turned off and an automatic position correction signal is sent to stepper motors to adjust the head position via the couch mount motion platform. The corrected location is confirmed before the treatment beam is turned on. A proto-type has been developed and is currently being tested for feasibility.

File Number: 1830

IP Protection

License Online

This innovation currently is not available for online licensing. Please contact the case manager at University of Chicago for more information.

request more info