Tracking accuracy of a real-time fiducial tracking system for patient positioning and monitoring in radiation therapy.
OBJECTIVE
In radiation therapy there is a need to accurately know the location of the target in real time. A novel radioactive tracking technology has been developed to answer this need. The technology consists of a radioactive implanted fiducial marker designed to minimize migration and a linac mounted tracking device. This study measured the static and dynamic accuracy of the new tracking technology in a clinical radiation therapy environment.


METHODS
The tracking device was installed on the linac gantry. The radioactive marker was located in a tissue equivalent phantom. Marker location was measured simultaneously by the radioactive tracking system and by a Microscribe G2 coordinate measuring machine (certified spatial accuracy of 0.38 mm). Localization consistency throughout a volume and absolute accuracy in the Fixed coordinate system were measured at multiple gantry angles over volumes of at least 10 cm in diameter centered at isocenter. Dynamic accuracy was measured with the marker located inside a breathing phantom.


RESULTS
The mean consistency for the static source was 0.58 mm throughout the tested region at all measured gantry angles. The mean absolute position error in the Fixed coordinate system for all gantry angles was 0.97 mm. The mean real-time tracking error for the dynamic source within the breathing phantom was less than 1 mm.


CONCLUSIONS
This novel radioactive tracking technology has the potential to be useful in accurate target localization and real-time monitoring for radiation therapy.
Shchory
Tal
T
Navotek Medical, Ltd., Yokneam, Israel.
Schifter
Dan
D
Lichtman
Rinat
R
Neustadter
David
D
Corn
Benjamin W
BW
D003199:Computer Systems; D004867:Equipment Design; D006801:Humans; D008297:Male; D056888:Patient Positioning; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D019736:Prostheses and Implants; D011834:Radiation Monitoring / Q000295:instrumentation / Q000379:methods; D011851:Radioactivity; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012119:Respiration