Radioactive Tracking System Research Articles

Tracking Accuracy of a Real-Time Fiducial Tracking System for Patient Positioning and Monitoring in Radiation Therapy

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. 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. 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. This novel radioactive tracking technology has the potential to be useful in accurate target localization and real-time monitoring for radiation therapy.

Accuracy of a Radioactive Tracking System in Canine Prostate

Accuracy of a Radioactive Tracking System in Canine Prostate

Positioning Accuracy of a Gantry-mounted Radioactive Tracking System on a Varian Trilogy Linac

Positioning Accuracy of a Gantry-mounted Radioactive Tracking System on a Varian Trilogy Linac

SU‐FF‐J‐64: Robustness of a Gantry‐Mounted Radioactive Tracking System in a Clinical Radiation Therapy Environment

Purpose: To examine the robustness of a gantry mounted radioactive tracking system in 6MV and 10MV clinical radiation therapy environments. Method and Materials: The gantry‐mounted tracking system was installed in several radiation therapy treatment rooms. Total dose equivalent to 20 treatment sessions was delivered at 6MV or 10MV in a few fractions (within 1 hour) to a phantom containing a radioactive marker (Ir192). During irradiation the tracking system was operating and system parameters were recorded before, during and immediately after irradiation. Recorded data was analyzed to assess system performance and the accumulated effects of radiation on the system. The radioactive marker location measured by the tracking system was monitored during and after irradiation to test for accuracy and stability. The spectra of the signals from the radioactive marker before and after irradiation were compared to see if any shift in spectrum is observed. After 10MV irradiation, background signal level was monitored to analyze the halflives of the isotopes resulting from neutron activation. Results: There was no significant change in signal spectrum after irradiation and no cumulative influence on system performance was observed. Tracking is temporarily interrupted during 10MV irradiation and is resumed within a few seconds after irradiation despite the increased background noise resulting from neutron activation which decays with a half life of approximately 105 seconds. At 6MV, the system maintains tracking accuracy and performance throughout irradiation despite an increased background noise level. The system adjusts to the changes in background noise level at the beginning and end of irradiation in under 3 seconds. Conclusion: The radioactive tracking system is robust in the radiation environment. There is no observable effect or malfunction after exposure to radiation. The system is capable of tracking a radioactive marker during irradiation at 6MV. Conflict of Interest: Research sponsored by Navotek Medical Ltd.

SU‐FF‐J‐48: Localization Accuracy of a Gantry‐Mounted Radioactive Tracking System in the Clinical Radiation Therapy Environment

Purpose: The submillimeter accuracy of a novel gantry‐mounted radioactive fiducial tracking system has been reported previously in a number of semi‐clinical scenarios. These have included tissue equivalent phantoms without bones, and antomical phantoms including bones, but with measurements being made from a single gantry angle that does not include potential interference from the bones and the patient couch and potential tracking system alignment inaccuracy due to gantry and collimator rotation. In this study the gantry‐mounted tracking system is tested in a more realistic clinical scenario. This study used an anatomical phantom with bones placed at multiple positions about the isocenter and made localization measurements with the gantry and collimator at various angles. Method and Materials: The tracking device was installed on a Varian Trilogy® linac gantry. The radioactive marker was located at the approximate position of the prostate in an anatomical tissue equivalent phantom on the patient couch. Actual marker location was measured using a Microscribe MLX coordinate measuring machine (CMM) arm (certified spatial accuracy of 0.08 mm). The marker was attached to the tip of the CMM arm, which was inserted into a hole in the phantom, and its location was measured simultaneously by the CMM and the tracking system. 102 localization accuracy measurements were made at locations covering a 10cm diameter sphere centered at the linac iso‐center with varying gantry and collimator angles including those that would potentially induce interference due to bones and the patient couch. Results: The mean localization error for all measured positions and gantry and collimator angles was less than 1mm. Conclusion: The gantry‐mounted radioactive tracking system maintains sufficient accuracy for radiation therapy patient localization and monitoring in a real clinical environment even in the presence of bones and patient couch interference. Conflict of Interest: Research sponsored by Navotek Medical Ltd.