Commissioning of a fluoroscopic-based real-time markerless tumor tracking system in a superconducting rotating gantry for carbon-ion pencil beam scanning treatment.

Purpose: To perform the final quality assurance of our fluoroscopic-based markerless tumor tracking for gated carbon-ion pencil beam scanning (C-PBS) radiotherapy using a rotating gantry system, we evaluated the geometrical accuracy and tumor tracking accuracy using a moving chest phantom with simulated respiration.

Methods: The positions of the dynamic flat panel detector (DFPD) and x-ray tube are subject to changes due to gantry sag. To compensate for this, we generated a geometrical calibration table (gantry flex map) in 15° gantry angle steps by the bundle adjustment method.

[Experimental study on treatment planning verification using a positron emitting (10)C beam for heavy-ion radiotherapy.].

An advantage of heavy-ion therapy is its good dose concentration. A limit for full use of this desirable feature comes from range ambiguities in treatment planning. The treatment planning is based on X-ray CT measurements, and the range ambiguities are mainly due to an error in calibration of the CT number.

[The examination of optimal positron emitting nuclide in the estimation of attainment depth within the body of RI beams by positron camera].

The (10)C and (11)C beam stop position in a homogeneous phantom was measured using the range verification system in HIMAC. This system was developed to clear uncertainty of beam range within the patient body in heavy ion radiotherapy. In this system, a target is irradiated with RI beams ((11)C or (10)C) and the distribution of the beam end-points are measured by a positron camera.

Range verification system using positron emitting beams for heavy-ion radiotherapy.

It is desirable to reduce range ambiguities in treatment planning for making full use of the major advantage of heavy-ion radiotherapy, that is, good dose localization. A range verification system using positron emitting beams has been developed to verify the ranges in patients directly. The performance of the system was evaluated in beam experiments to confirm the designed properties.